aboutsummaryrefslogblamecommitdiffstats
path: root/lib/snmp/src/agent/snmpa_agent.erl
blob: 9bed6e554eabd480a80501e9d5803d587416e693 (plain) (tree)
1
2
3
4
5
6
7
8
9
10
2645
2646
2647
2648
2649
2650
2651
2652
2653
2654
2655
2656
2657
2658
2659
2660
2661
2662
2663
2664
2665
2666
2667
2668
2669
2670
2671
2672
2673
2674
2675
2676
2677
2678
2679
2680
2681
2682
2683
2684
2685
2686
2687
2688
2689
2690
2691
2692
2693
2694
2695
2696
2697
2698
2699
2700
2701
2702
2703
2704
2705
2706
2707
2708
2709
2710
2711
2712
2713
2714
2715
2716
2717
2718
2719
2720
2721
2722
2723
2724
2725
2726
2727
2728
2729
2730
2731
2732
2733
2734
2735
2736
2737
2738
2739
2740
2741
2742
2743
2744
2745
2746
2747
2748
2749
2750
2751
2752
2753
2754
2755
2756
2757
2758
2759
2760
2761
2762
2763
2764
2765
2766
2767
2768
2769
2770
2771
2772
2773
2774
2775
2776
2777
2778
2779
2780
2781
2782
2783
2784
2785
2786
2787
2788
2789
2790
2791
2792
2793
2794
2795
2796
2797
2798
2799
2800
2801
2802
2803
2804
2805
2806
2807
2808
2809
2810
2811
2812
2813
2814
2815
2816
2817
2818
2819
2820
2821
2822
2823
2824
2825
2826
2827
2828
2829
2830
2831
2832
2833
2834
2835
2836
2837
2838
2839
2840
2841
2842
2843
2844
2845
2846
2847
2848
2849
2850
2851
2852
2853
2854
2855
2856
2857
2858
2859
2860
2861
2862
2863
2864
2865
2866
2867
2868
2869
2870
2871
2872
2873
2874
2875
2876
2877
2878
2879
2880
2881
2882
2883
2884
2885
2886
2887
2888
2889
2890
2891
2892
2893
2894
2895
2896
2897
2898
2899
2900
2901
2902
2903
2904
2905
2906
2907
2908
2909
2910
2911
2912
2913
2914
2915
2916
2917
2918
2919
2920
2921
2922
2923
2924
2925
2926
2927
2928
2929
2930
2931
2932
2933
2934
2935
2936
2937
2938
2939
2940
2941
2942
2943
2944
2945
2946
2947
2948
2949
2950
2951
2952
2953
2954
2955
2956
2957
2958
2959
2960
2961
2962
2963
2964
2965
2966
2967
2968
2969
2970
2971
2972
2973
2974
2975
2976
2977
2978
2979
2980
2981
2982
2983
2984
2985
2986
2987
2988
2989
2990
2991
2992
2993
2994
2995
2996
2997
2998
2999
3000
3001
3002
3003
3004
3005
3006
3007
3008
3009
3010
3011
3012
3013
3014
3015
3016
3017
3018
3019
3020
3021
3022
3023
3024
3025
3026
3027
3028
3029
3030
3031
3032
3033
3034
3035
3036
3037
3038
3039
3040
3041
3042
3043
3044
3045
3046
3047
3048
3049
3050
3051
3052
3053
3054
3055
3056
3057
3058
3059
3060
3061
3062
3063
3064
3065
3066
3067
3068
3069
3070
3071
3072
3073
3074
3075
3076
3077
3078
3079
3080
3081
3082
3083
3084
3085
3086
3087
3088
3089
3090
3091
3092
3093
3094
3095
3096
3097
3098
3099
3100
3101
3102
3103
3104
3105
3106
3107
3108
3109
3110
3111
3112
3113
3114
3115
3116
                   
  
                                                        
  



                                                                      
  


                                                                         
  












                                              
                                             
                                                    
                              















                                                       
                                  








                                                                 
                               
                                                  

                                    

                                                             
                                                
                                          
                    
                                      
                     
                               













                                                













                                                                      











                                                                        
                                                 
                                                            
                                                           
                                    



                                                          
                                                           


                                                                    




                                                       







                                                                    









                                                                     
   



                                                                   
   
                                                                   
 













                                                 
                                   



































                                                                      


                                                         


                                                



                                                               






















































                                                                


                                                  













                                                                 





















                                                              
                                     


                                                         




























                                                                
                                        
















                                                           
                                            



























































                                                                         
                                                       








































































                                                                              
                    
                         



                                          
                                                            
                    
                           



                                            








































                                                                              



                                                   
                                                              







                                                    







                                                     










                                                                             








                                                              
                     
 




















































































                                                                                            
 


                                                                            












































































                                                                       
                                                            








                                                                        
                                                       
                                             

                                    
                                                               








                                                 
                                                                             




                                                           
                                               
                                       
                                                                  
                                                                              

















                                                                          
                                           
                                                                  
                                                                              






                                                 
                     
 
                                                                




















                                                                             
                                   
                                               




                                                                 
                                               
                                              
                                                                       
                                                                             






                                                 
                     


































































                                                                         
 































                                                                       
 
                                                              
                                             

                                    
                                                               









                                                       

                                                                        




                                                           
                                               
                                                                  
                                                                              







                                                       










                                                                          
                                           
                                                                  
                                                                              







                                                       
                     
 
                        
                                                                       





































                                                                                                           
                                                         











                                                                        
                                                             


















                                                                             
                                                             



                                                       
                                                                




















































                                                                               
                    

                                                          



                                                                 
 
                    

                                                            



                                                                   





































                                                                      
                                                                         














                                                      
 
                                                                        

                                                       














































                                                                         
                                                         


                                                 
                                                   



                                             
                                                              


                                                       
                                                        

                                                   
 






                                                         
                                                             
                                                      
                                                                    

                              
                                                                       






















































                                                                               
                                                                    


























                                                                         








































































                                                            



                               



                                                              























                                                                   
                                  
                                             
                                








                                    
                                                       
 
                                  
 



                                                 































































                                                                             
                                                                            

                                                              

























                                                                             
                                                 
















                                                                   

                                                                   
                 
                                                                       
                                                   
                                                               
                                              
                                              
                                                           
                                                                     
 
                                                          



                                                              
                                                              
                                                   
                         
                                                                      
                                                                






                                                              




































                                                                           
                                                                           



                                                                         
                                                                       










































                                                                            
                                                                        

                                                          
                                                               


















                                                                     





                                                                   
                                                         
                                                         
                                                                    




                                                                    
                                                                                
                       

                                         
                                                       
                                                       
                                                                     
                                                                
                                                     
                                                     
                                                                                




                                                                        
                    
                                                             


                                                                              

                                                              
                                                                    
 
                                                                  






                                                                  
                                                                        











                                                                        
                                                          
                            
 
                                                             
                                                        

                                         

                                                      





















































                                                                              
                                       




                                             
 
                                              



                                                                                
                    




                                                             




                                                                               
                                            



                                      
                                                                          



                                                                 
                        

                                                                         
                                                                              



                                                              
                                                               
                                                             





                                                               
                                                                           













                                                            
                                                                             



                                                         
                                                                             




                                                         
                                                                  
                                            














                                                         
                                                                         
                                                          




                                                                    
                                                                        
                                                         
        
                                                                        
                                                
                                                                   

                                                                          
                                               



                                                                  
                                                                      



                                                               
                                                                          
                                                        


                                                                     
                                                                       
                                                                          
































































































                                                                              
                                                                       










































































                                                                                  
                                                               
                                                               

                                                                




























































































































































                                                                                
                                                                         




                                                
                                                    
                                                                       
                                               


















                                                                                
                                               


                                                      
                                                       














                                                                         




                                                   
                                              
                                                                               






                                                                           
                                              






















































                                                                      
                                                                         






















































































































































































































































































































































































































































































                                                                               
 




                                                                              
                                   
                                                        
                         
                                                                 
 
                    
                                     



                                                              
                             
                                                                   



                                           
                                                         


                                                                             
                                                                              
 

                                                                                    

                                                 
                                                     
                                                            
                                   
                                                       
                                                                            
                                       




                                                              
                                                                           




                                                                  
                                                 


                                                             
                                                                               
                                              


                                                                       
                                                               
                                                                
                                         

                                                              
                                                                       
                                                               
                                                  
                                                                





                                                                         
                                                                



                                                                      
                                                                        







                                                              
                                                        






                                                                     
                                                                        






                                                    
                                                                






                                                       
                                                                



                                                                         
                                                                        










                                                                                
                                                                        


                                                                               
                                                                        













                                                                       
                                                        




                                                     
                                                                          








                                                                           
                                                                               

                                                                       
                                                                           










                                                               
                                                              


                                                                    


                                            








                                                                  
 




















































































































































































































































                                                                               




                                                                   
                                                                    
                                                                                
                                       


                                     

                                                                                
                                                                 
                                
                                                    
                                                     
                                               







                                                                               
                                                      

                                                                             
                                                                               






                                                                        


                                                                             






                                                           
 















































                                                                       
                                                                           
                             


                                                                              






                                        
                                                              





                                                                    

                                   
                                                                          


                                            
                                                         



                                                                     
                                                              









                                                                  


                                                 
                                    

                                                      
                                                    
                                       
                                                           
                                                             

                                                                               
                                                            

                                                              

                                                                  








                                                              
                                         
                                      
                                                              










































































































































                                                                                
                                                                               































































































































































































































                                                                                        
 
































































                                                                          










                                                                        












































                                                                
                                                   






















































































































                                                                        






                                    














                                                                        
                                  











                                                        

                                           




















                                                   

                                    













                                                                        
%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 1996-2013. All Rights Reserved.
%%
%% The contents of this file are subject to the Erlang Public License,
%% Version 1.1, (the "License"); you may not use this file except in
%% compliance with the License. You should have received a copy of the
%% Erlang Public License along with this software. If not, it can be
%% retrieved online at http://www.erlang.org/.
%%
%% Software distributed under the License is distributed on an "AS IS"
%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
%% the License for the specific language governing rights and limitations
%% under the License.
%%
%% %CopyrightEnd%
%%
-module(snmpa_agent).

-include_lib("kernel/include/file.hrl").
-include("snmpa_internal.hrl").
-include("snmp_types.hrl").
-include("snmp_debug.hrl").
-include("snmp_verbosity.hrl").
-include("SNMP-FRAMEWORK-MIB.hrl").

%% External exports
-export([start_link/4, start_link/5, stop/1]).
-export([subagent_set/2, 
	 load_mibs/3, unload_mibs/3, 
	 which_mibs/1, whereis_mib/2, info/1,
	 register_subagent/3, unregister_subagent/2,
	 send_notification/3, 
         register_notification_filter/5,
         unregister_notification_filter/2,
         which_notification_filter/1,
 	 get_net_if/1]).
-export([
	 discovery/6, 
	 is_originating_discovery_enabled/0,
	 is_terminating_discovery_enabled/0,
	 terminating_discovery_stage2/0,
	 terminating_trigger_username/0
	]).
-export([verbosity/2, dump_mibs/1, dump_mibs/2]).
-export([validate_err/3, make_value_a_correct_value/3, 
	 do_get/3, do_get/4, 
	 get/2, get/3, get_next/2, get_next/3]).
-export([mib_of/1, mib_of/2, me_of/1, me_of/2,
	 invalidate_mibs_cache/1,
	 which_mibs_cache_size/1, 
	 enable_mibs_cache/1, disable_mibs_cache/1,
	 gc_mibs_cache/1, gc_mibs_cache/2, gc_mibs_cache/3,
	 enable_mibs_cache_autogc/1, disable_mibs_cache_autogc/1,
	 update_mibs_cache_age/2, 
	 update_mibs_cache_gclimit/2]).
-export([get_agent_mib_storage/0, db/1, 
	 backup/2]).
-export([get_log_type/1,      set_log_type/2]).
-export([get_request_limit/1, set_request_limit/2]).
-export([invalidate_ca_cache/0]).
-export([increment_counter/3]).
-export([restart_worker/1, restart_set_worker/1]).

%% For backward compatibillity
-export([send_trap/6, send_trap/7]).

%% Internal exports
-export([init/1, handle_call/3, handle_cast/2, handle_info/2,
	 terminate/2, code_change/3, tr_var/2, tr_varbind/1,
	 handle_pdu/8, worker/2, worker_loop/1, 
	 do_send_trap/7, do_send_trap/8]).
%% <BACKWARD-COMPAT>
-export([handle_pdu/7, 
	 load_mibs/2, unload_mibs/2]).
%% </BACKWARD-COMPAT>

-include("snmpa_internal.hrl").

-ifndef(default_verbosity).
-define(default_verbosity,silence).
-endif.

-define(empty_pdu_size, 21).

-ifdef(snmp_extended_verbosity).
-define(vt(F,A), ?vtrace(F, A)).
-else.
-define(vt(_F, _A), ok).
-endif.

-define(DISCO_TERMINATING_TRIGGER_USERNAME, "").

-ifdef(snmp_debug).
-define(GS_START_LINK3(Prio, Parent, Ref, Opts),
        gen_server:start_link(?MODULE, [Prio, Parent, Ref, Opts],
                              [{debug,[trace]}])).
-define(GS_START_LINK4(Prio, Name, Parent, Ref, Opts),
        gen_server:start_link({local, Name}, ?MODULE, 
			      [Prio, Parent, Ref, Opts],
                              [{debug,[trace]}])).
-else.
-define(GS_START_LINK3(Prio, Parent, Ref, Opts),
        gen_server:start_link(?MODULE, [Prio, Parent, Ref, Opts],[])).
-define(GS_START_LINK4(Prio, Name, Parent, Ref, Opts),
        gen_server:start_link({local, Name}, ?MODULE, 
			      [Prio, Parent, Ref, Opts],[])).
-endif.

%% Increment this whenever a change is made to the worker interface 
-define(WORKER_INTERFACE_VERSION, 1).

%% -- Utility macros for creating worker commands --
-define(mk_pdu_wreq(Vsn, Pdu, PduMS, ACMData, Address, GbMaxVBs, Extra),
	#wrequest{cmd  = handle_pdu, 
		  info = [{vsn,        Vsn}, 
			  {pdu,        Pdu}, 
			  {pdu_ms,     PduMS}, 
			  {acm_data,   ACMData}, 
			  {addr,       Address}, 
			  {gb_max_vbs, GbMaxVBs}, 
			  {extra,      Extra}]}).
-define(mk_send_trap_wreq(TrapRec, NotifyName, ContextName, 
			  Recv, Vbs, LocalEngineID, Extra),
	#wrequest{cmd  = send_trap, 
		  info = [{trap_rec,        TrapRec}, 
			  {notify_name,     NotifyName}, 
			  {context_name,    ContextName}, 
			  {receiver,        Recv}, 
			  {varbinds,        Vbs}, 
			  {local_engine_id, LocalEngineID},
			  {extra,           Extra}]}).
-define(mk_terminate_wreq(), #wrequest{cmd = terminate, info = []}).
-define(mk_verbosity_wreq(V), #wrequest{cmd  = verbosity, 
					info = [{verbosity, V}]}).


-record(notification_filter, {id, mod, data}).
-record(disco, 
	{from, rec, sender, target, engine_id, 
	 sec_level, ctx, ivbs, stage, handler, extra}).

%% This record is used when sending requests to the worker processes
-record(wrequest, 
	{
	  version = ?WORKER_INTERFACE_VERSION, 
	  cmd, 
	  info
	 }
       ).


%%-----------------------------------------------------------------
%% The agent is multi-threaded, i.e. each request is handled
%% by a separate process.  However, in the normal case, there
%% is just one request handled at the time.  In order to improve
%% performance, there is always two worker processes alive.  They are
%% created at initialization time.  There is always one worker
%% dedicated to SET-handling.  When a get*-request is received,
%% it is sent to the worker, and the worker is marked as busy.
%% If a request is received when the worker is busy, a new temporary
%% worker is spawned.
%% 
%% Code change
%% ===========
%% Note that the worker(s) execute the same module as the master
%% agent. For code change we have two options - ignore the workers,
%% or send them a code change message.
%% 
%%-----------------------------------------------------------------

-record(state, {type, 
		parent, 
		worker, 
		worker_state = ready,
		set_worker, 
		multi_threaded, 
		ref, 
		vsns,
		nfilters = [],
		note_store,
		mib_server,   %% Currently unused
		net_if,       %% Currently unused
		net_if_mod,   
		backup,
		disco,
		mibs_cache_request,
		gb_max_vbs}).


%%%-----------------------------------------------------------------
%%% This module implements the agent machinery; both for the master
%%% agent and the subagents.
%%%-----------------------------------------------------------------
%%% Table of contents
%%% =================
%%% 1. Interface
%%% 2. Main loop
%%% 3. GET REQUEST
%%% 4. GET-NEXT REQUEST
%%% 5. GET-BULK REQUEST
%%% 6. SET REQUEST
%%% 7. Misc functions
%%%-----------------------------------------------------------------

%%-----------------------------------------------------------------
%% Parent is a Pid (of master_agent) or none
%% Options is a list of Option, where Option is
%%   {mibs, Mibs}
%%   {net_if, NetIfModule}
%%   {priority, Prio}
%%   {verbosity, Verbosity}
%%   {multi_threaded, Bool} true means that SETs are serialized,
%%      while GETs are concurrent, even with a SET.
%%   {set_mechanism, SetModule}           % undocumented feature
%%
%% The following options are now removed - they are not needed
%% anymore when VACM is standard for authentication, and works
%% with all versions, and trap sending is standardized too.
%%   {authentication_service, AuthModule} % undocumented feature
%%   {trap_mechanism, TrapModule}         % undocumented feature
%% Note: authentication_service is reintroduced for AXD301 (OTP-3324).
%%-----------------------------------------------------------------
start_link(Prio, Parent, Ref, Options) ->
    ?d("start_link -> entry with"
       "~n   Prio:    ~p"
       "~n   Parent:  ~p"
       "~n   Ref:     ~p"
       "~n   Options: ~p", [Prio, Parent, Ref, Options]),
    ?GS_START_LINK3(Prio, Parent, Ref, Options).

start_link(Prio, Name, Parent, Ref, Options) ->
    ?d("start_link -> entry with"
       "~n   Prio:    ~p"
       "~n   Name:    ~p"
       "~n   Parent:  ~p"
       "~n   Ref:     ~p"
       "~n   Options: ~p", [Prio, Name, Parent, Ref, Options]),
    ?GS_START_LINK4(Prio, Name, Parent, Ref, Options).

stop(Agent) -> call(Agent, stop).

restart_worker(Agent) ->
    call(Agent, restart_worker).

restart_set_worker(Agent) ->
    call(Agent, restart_set_worker).

get_log_type(Agent) ->
    call(Agent, get_log_type).

set_log_type(Agent, NewType) ->
    call(Agent, {set_log_type, NewType}).

get_request_limit(Agent) ->
    call(Agent, get_request_limit).

set_request_limit(Agent, NewLimit) ->
    call(Agent, {set_request_limit, NewLimit}).

mib_of(Oid) when is_list(Oid) ->
    mib_of(snmp_master_agent, Oid).

mib_of(Agent, Oid) when is_list(Oid) ->
    call(Agent, {mib_of, Oid}).

me_of(Oid) when is_list(Oid) ->
    me_of(snmp_master_agent, Oid).

me_of(Agent, Oid) when is_list(Oid) ->
    call(Agent, {me_of, Oid}).


invalidate_mibs_cache(Agent) ->
    call(Agent, {mibs_cache_request, invalidate_cache}).


gc_mibs_cache(Agent) ->
    call(Agent, {mibs_cache_request, gc_cache}).

gc_mibs_cache(Agent, Age) ->
    call(Agent, {mibs_cache_request, {gc_cache, Age}}).

gc_mibs_cache(Agent, Age, GcLimit) ->
    call(Agent, {mibs_cache_request, {gc_cache, Age, GcLimit}}).


enable_mibs_cache(Agent) ->
    call(Agent, {mibs_cache_request, enable_cache}).

disable_mibs_cache(Agent) ->
    call(Agent, {mibs_cache_request, disable_cache}).


which_mibs_cache_size(Agent) ->
    call(Agent, {mibs_cache_request, cache_size}).


enable_mibs_cache_autogc(Agent) ->
    call(Agent, {mibs_cache_request, enable_autogc}).

disable_mibs_cache_autogc(Agent) ->
    call(Agent, {mibs_cache_request, disable_autogc}).


update_mibs_cache_gclimit(Agent, GcLimit) ->
    call(Agent, {mibs_cache_request, {update_gclimit, GcLimit}}).


update_mibs_cache_age(Agent, Age) ->
    call(Agent, {mibs_cache_request, {update_age, Age}}).


increment_counter(Counter, Initial, Max) ->
    %% This is to make sure no one else increments our counter
    Key = {Counter, self()}, 

    %% Counter data
    Position  = 2, 
    Increment = 1, 
    Threshold = Max,
    SetValue  = Initial, 
    UpdateOp  = {Position, Increment, Threshold, SetValue},
    
    %% And now for the actual increment
    Tab = snmp_agent_table, 
    case (catch ets:update_counter(Tab, Key, UpdateOp)) of
	{'EXIT', {badarg, _}} ->
	    %% Oups, first time
	    ets:insert(Tab, {Key, Initial}),
	    Initial;
	Next when is_integer(Next) ->
	    Next
    end.


init([Prio, Parent, Ref, Options]) ->
    ?d("init -> entry with"
       "~n   Prio:    ~p"
       "~n   Parent:  ~p"
       "~n   Ref:     ~p"
       "~n   Options: ~p", [Prio, Parent, Ref, Options]),
    case (catch do_init(Prio, Parent, Ref, Options)) of
	{ok, State} ->
	    ?vdebug("started",[]),
	    {ok, State};
	{error, Reason} ->
	    config_err("failed starting agent: ~n~p", [Reason]),
	    {stop, Reason}
    end.

do_init(Prio, Parent, Ref, Options) ->
    process_flag(priority, Prio),
    put(sname,short_name(Parent)),
    put(verbosity,get_verbosity(Options)),
    ?vlog("starting with: "
	  "~n   Prio:    ~p"
	  "~n   Parent:  ~p"
	  "~n   Ref:     ~p"
	  "~n   Options: ~p",[Prio, Parent, Ref, Options]),

    Mibs       = get_mibs(Options),
    SetModule  = get_set_mechanism(Options),
    put(set_module, SetModule),

    %% OTP-3324. For AXD301.
    AuthModule = get_authentication_service(Options),
    put(auth_module, AuthModule),

    MultiT  = get_multi_threaded(Options),
    Vsns    = get_versions(Options),

    GbMaxVbs = get_gb_max_vbs(Options), 

    NS = start_note_store(Prio, Ref, Options),
    {Type, NetIfPid, NetIfMod} = 
	start_net_if(Parent, Prio, Ref, Vsns, NS, Options),

    MibPid = start_mib_server(Prio, Ref, Mibs, Options),
    
    put(net_if, NetIfPid),
    put(mibserver, MibPid),
    process_flag(trap_exit, true),
    {Worker, SetWorker} = workers_start(MultiT),
    {ok, #state{type           = Type, 
		parent         = Parent, 
		worker         = Worker,
		set_worker     = SetWorker,
		multi_threaded = MultiT, 
		ref            = Ref,
		vsns           = Vsns,
		note_store     = NS,
		net_if_mod     = NetIfMod,
		gb_max_vbs     = GbMaxVbs}}.


start_note_store(Prio, Ref, Options) ->
    ?vdebug("start_note_store -> with Prio: ~p", [Prio]),
    NsOpts = get_note_store_opt(Options),

    ?vtrace("start_note_store -> NsOpts: ~p", [NsOpts]),

    case (catch snmpa_misc_sup:start_note_store(Prio, Ref, NsOpts)) of
	{ok, Pid} ->
	    ?vdebug("start_note_store -> Pid: ~p", [Pid]),
	    Pid;
	{error, Reason} -> 
	    ?vinfo("error starting note store: ~n~p",[Reason]),
	    throw({error, {note_store_error, Reason}});
	{'EXIT', Reason} ->
	    ?vinfo("exit starting note store: ~n~p",[Reason]),
	    throw({error, {note_store_exit, Reason}});
	Error ->
	    ?vinfo("failed starting note store: ~n~p",[Error]),
	    throw({error, {note_store_failed, Error}})
    end.
    

start_net_if(none, Prio, Ref, Vsns, NoteStore, Options) ->
    ?vdebug("start_net_if(none) -> with Prio: ~p", [Prio]),
    NetIfOpts = get_net_if_opt(Options),
    Verbosity = get_net_if_verbosity(NetIfOpts),
    Mod       = get_net_if_module(NetIfOpts),
    NiOptions = get_net_if_options(NetIfOpts),
    NiOpts    = [{versions,  Vsns}, 
		 {verbosity, Verbosity} | NiOptions],
    
    ?vtrace("start_net_if -> "
	    "~n   Mod:    ~p"
	    "~n   NiOpts: ~p",[Mod, NiOpts]),

    case (catch snmpa_misc_sup:start_net_if(Prio, NoteStore, Ref, self(),
					    Mod, NiOpts)) of
	{ok, Pid} -> 
	    ?vdebug("start_net_if -> Pid: ~p", [Pid]),
	    {master_agent, Pid, Mod};
	{error, Reason} -> 
	    ?vinfo("error starting net if: ~n~p",[Reason]),
	    throw({error, {net_if_error, Reason}});
	{'EXIT', Reason} ->
	    ?vinfo("exit starting net if: ~n~p",[Reason]),
	    throw({error, {net_if_exit, Reason}});
	Error ->
	    ?vinfo("failed starting net if: ~n~p",[Error]),
	    throw({error, {net_if_failed, Error}})
    end;
start_net_if(Parent, _Prio, _Ref, _Vsns, _NoteStore, _Options) 
  when is_pid(Parent) ->
    ?vdebug("start_net_if(~p) -> subagent => ignore", [Parent]),
    {subagent, undefined, undefined}.
    
    
start_mib_server(Prio, Ref, Mibs, Options) ->
    ?vdebug("start_mib_server -> with Prio: ~p", [Prio]),
    MibStorage = get_mib_storage(Options),
    MibsOpts   = [{mib_storage, MibStorage} | 
		  get_option(mib_server, Options, [])],

    ?vtrace("start_mib_server -> "
	    "~n   Mibs:     ~p"
	    "~n   MibsOpts: ~p", [Mibs, MibsOpts]),

    case (catch snmpa_misc_sup:start_mib_server(Prio, Ref, Mibs, MibsOpts)) of
	{ok, Pid} ->
	    ?vdebug("start_mib_server -> Pid: ~p", [Pid]),
	    Pid;
	{error, Reason} -> 
	    ?vinfo("error starting mib server: ~n~p",[Reason]),
	    throw({error, {mib_server_error, Reason}});
	{'EXIT', Reason} ->
	    ?vinfo("exit starting mib server: ~n~p",[Reason]),
	    throw({error, {mib_server_exit, Reason}});
	Error ->
	    ?vinfo("failed starting mib server: ~n~p",[Error]),
	    throw({error, {mib_server_failed, Error}})
    end.


%%-----------------------------------------------------------------
%% Purpose: We must calculate the length of an empty Pdu.  This
%%          length is used to calculate the max pdu size allowed
%%          for each get-bulk-request. This size is 
%%          dependent on the varbinds. It is calculated
%%          as EmptySize + 8.  8 comes from the fact that the
%%          maximum pdu size needs 31 bits which needs 5 * 7 bits to be
%%          expressed. One 7bit octet is already present in the
%%          empty pdu, leaving 4 more 7bit octets. The length is
%%          repeated twice, once for the varbinds, and once for the
%%          entire pdu; 2 * 4 = 8.
%% Actually, this function is not used, we use a constant instead.
%%-----------------------------------------------------------------
%% Ret: 21
%% empty_pdu() ->
%%     Pdu = #pdu{type         = 'get-response', 
%%                request_id   = 1,
%% 	          error_status = noError, 
%%                error_index  = 0, 
%%                varbinds     = []},
%%     length(snmp_pdus:enc_pdu(Pdu)) + 8.


%%%--------------------------------------------------
%%% 1. Interface
%%%--------------------------------------------------
%% Called by administrator (not subagent; deadlock could occur)
register_subagent(Agent, SubTreeOid, SubagentPid) ->
    call(Agent, {register_subagent, SubTreeOid, SubagentPid}).

%% Called by administrator (not subagent; deadlock could occur)
unregister_subagent(Agent, SubagentOidOrPid) ->
    call(Agent, {unregister_subagent, SubagentOidOrPid}).


%%-----------------------------------------------------------------
%% These subagent_ functions either return a value, or exits
%% with {nodedown, Node} | Reason.
%%-----------------------------------------------------------------
subagent_get(SubAgent, Varbinds, IsNotification) ->
    PduData = get_pdu_data(),
    call(SubAgent, {subagent_get, Varbinds, PduData, IsNotification}).

subagent_get_next(SubAgent, MibView, Varbinds) ->
    PduData = get_pdu_data(),
    call(SubAgent, {subagent_get_next, MibView, Varbinds, PduData}).

subagent_set(SubAgent, Arguments) ->
    PduData = get_pdu_data(),
    call(SubAgent, {subagent_set, Arguments, PduData}).


%% Called by administrator (not agent; deadlock would occur)
%% <BACKWARD-COMPAT>
load_mibs(Agent, Mibs) ->
    load_mibs(Agent, Mibs, false).
%% </BACKWARD-COMPAT>

load_mibs(Agent, Mibs, Force) ->
    call(Agent, {load_mibs, Mibs, Force}).

%% Called by administrator (not agent; deadlock would occur)
%% <BACKWARD-COMPAT>
unload_mibs(Agent, Mibs) ->
    unload_mibs(Agent, Mibs, false).
%% </BACKWARD-COMPAT>

unload_mibs(Agent, Mibs, Force) ->
    call(Agent, {unload_mibs, Mibs, Force}).

which_mibs(Agent) ->
    call(Agent, which_mibs).

whereis_mib(Agent, Mib) ->
    call(Agent, {whereis_mib, Mib}).

info(Agent) ->
    call(Agent, info).


get_net_if(Agent) ->
    call(Agent, get_net_if).


register_notification_filter(Agent, Id, Mod, Args, Where) 
  when (Where =:= first) orelse (Where =:= last) ->
    case (catch verify_notification_filter_behaviour(Mod)) of
	ok ->
	    call(Agent, {register_notification_filter, Id, Mod, Args, Where});
	Error ->
	    Error
    end;
register_notification_filter(Agent, Id, Mod, Args, {Loc, _Id} = Where) 
  when (Loc =:= insert_before) orelse (Loc =:= insert_after) ->
    case (catch verify_notification_filter_behaviour(Mod)) of
	ok ->
	    call(Agent, {register_notification_filter, Id, Mod, Args, Where});
	 Error ->
	    Error
    end.

verify_notification_filter_behaviour(Mod) ->
    snmp_misc:verify_behaviour(snmpa_notification_filter, Mod).

unregister_notification_filter(Agent, Id) ->
    call(Agent, {unregister_notification_filter, Id}).

which_notification_filter(Agent) ->
    call(Agent, which_notification_filter).


send_notification(Agent, Notification, SendOpts) ->
    Msg = {send_notif, Notification, SendOpts},
    maybe_call(Agent, Msg).
    
%% <BACKWARD-COMPAT>
send_trap(Agent, Trap, NotifyName, CtxName, Recv, Varbinds) ->
    ?d("send_trap -> entry with"
       "~n   self():        ~p"
       "~n   Agent:         ~p [~p]"
       "~n   Trap:          ~p"
       "~n   NotifyName:    ~p"
       "~n   CtxName:       ~p"
       "~n   Recv:          ~p"
       "~n   Varbinds:      ~p", 
       [self(), Agent, wis(Agent), 
	Trap, NotifyName, CtxName, Recv, Varbinds]),
    SendOpts = [
		{receiver, Recv},
		{varbinds, Varbinds}, 
		{name,     NotifyName},
		{context,  CtxName}, 
		{extra,    ?DEFAULT_NOTIF_EXTRA_INFO}
	       ],
    send_notification(Agent, Trap, SendOpts).
    
send_trap(Agent, Trap, NotifyName, CtxName, Recv, Varbinds, LocalEngineID) ->
    ?d("send_trap -> entry with"
       "~n   self():        ~p"
       "~n   Agent:         ~p [~p]"
       "~n   Trap:          ~p"
       "~n   NotifyName:    ~p"
       "~n   CtxName:       ~p"
       "~n   Recv:          ~p"
       "~n   Varbinds:      ~p" 
       "~n   LocalEngineID: ~p", 
       [self(), Agent, wis(Agent), 
	Trap, NotifyName, CtxName, Recv, Varbinds, LocalEngineID]),
    SendOpts = [
		{receiver,        Recv},
		{varbinds,        Varbinds}, 
		{name,            NotifyName},
		{context,         CtxName}, 
		{extra,           ?DEFAULT_NOTIF_EXTRA_INFO}, 
		{local_engine_id, LocalEngineID}
	       ],
    send_notification(Agent, Trap, SendOpts).
    
%% </BACKWARD-COMPAT>


%% -- Discovery functions --

disco_opts() ->
    case ets:lookup(snmp_agent_table, discovery) of
	[] -> 
	    [];
	[{discovery, DiscoOptions}] ->
	    DiscoOptions
    end.
    
originating_disco_opts() ->
    DiscoOpts = disco_opts(),
    case lists:keysearch(originating, 1, DiscoOpts) of
	{value, {originating, OrigDisco}} ->
	    OrigDisco;
	_ ->
	    []
    end.
	
is_originating_discovery_enabled() ->
    OrigDisco = originating_disco_opts(), 
    case lists:keysearch(enable, 1, OrigDisco) of
	{value, {enable, false}} ->
	    false;
	_ ->
	    true
    end.
    
terminating_disco_opts() ->
    DiscoOpts = disco_opts(),
    case lists:keysearch(terminating, 1, DiscoOpts) of
	{value, {terminating, TermDisco}} ->
	    TermDisco;
	_ ->
	    []
    end.
	
is_terminating_discovery_enabled() ->
    TermDisco = terminating_disco_opts(),
    case lists:keysearch(enable, 1, TermDisco) of
	{value, {enable, false}} ->
	    false;
	_ ->
	    true
    end.
    
terminating_discovery_stage2() ->
    Default   = discovery, 
    TermDisco = terminating_disco_opts(),
    case lists:keysearch(stage2, 1, TermDisco) of
	{value, {stage2, Stage2}} when ((Stage2 =:= discovery) orelse (Stage2 =:= plain)) ->
	    Stage2;
	_ ->
	    Default 
    end.

terminating_trigger_username() ->
    Default   = ?DISCO_TERMINATING_TRIGGER_USERNAME,
    TermDisco = terminating_disco_opts(),
    case lists:keysearch(trigger_username, 1, TermDisco) of
	{value, {trigger_username, Trigger}} when is_list(Trigger) ->
	    Trigger;
	_ ->
	    Default
    end.

    
discovery(TargetName, Notification, ContextName, Varbinds, 
	  DiscoHandler, ExtraInfo) ->
    case is_originating_discovery_enabled() of
	true ->
	    Agent = snmp_master_agent, 
	    call(Agent, 
		 {discovery, 
		  TargetName, Notification, ContextName, Varbinds, 
		  DiscoHandler, ExtraInfo});
	false ->
	    {error, not_enabled}
    end.

wis(Pid) when is_pid(Pid) ->
    Pid;
wis(Atom) when is_atom(Atom) ->
    whereis(Atom).


forward_trap(Agent, TrapRecord, NotifyName, CtxName, Recv, Varbinds, 
	     ExtraInfo) ->
    Agent ! {forward_trap, TrapRecord, NotifyName, CtxName, Recv, Varbinds, 
	     ExtraInfo}.


%%-----------------------------------------------------------------
%% Args: Vars = [Oid]
%% Returns: [Value]
%% Called from a program to get variables.  Don't call this from
%% an instrumentation function; deadlock can occur!
%%-----------------------------------------------------------------
get(Agent, Vars) -> 
    call(Agent, {get, Vars, ""}).

get(Agent, Vars, Context) -> 
    call(Agent, {get, Vars, Context}).

get_next(Agent, Vars) -> 
    call(Agent, {get_next, Vars, ""}).

get_next(Agent, Vars, Context) -> 
    call(Agent, {get_next, Vars, Context}).


%%-----------------------------------------------------------------

backup(Agent, BackupDir) when is_list(BackupDir) ->
    call(Agent, {backup, BackupDir}).


%%-----------------------------------------------------------------
%% Runtime debug support.
%%-----------------------------------------------------------------
dump_mibs(Agent) -> 
    call(Agent, dump_mibs).
dump_mibs(Agent, File) when is_list(File) -> 
    call(Agent, {dump_mibs, File}).


%%-----------------------------------------------------------------
%% Runtime debug (verbosity) support.
%%-----------------------------------------------------------------
verbosity(net_if,Verbosity) -> 
    cast(snmp_master_agent,{net_if_verbosity,Verbosity});
verbosity(mib_server,Verbosity) -> 
    cast(snmp_master_agent,{mib_server_verbosity,Verbosity});
verbosity(note_store,Verbosity) -> 
    cast(snmp_master_agent,{note_store_verbosity,Verbosity});
verbosity(sub_agents,Verbosity) -> 
    cast(snmp_master_agent,{sub_agents_verbosity,Verbosity});
verbosity(master_agent,Verbosity) -> 
    cast(snmp_master_agent,{verbosity,Verbosity});
verbosity(Agent,{sub_agents,Verbosity}) -> 
    cast(Agent,{sub_agents_verbosity,Verbosity});
verbosity(Agent,Verbosity) -> 
    cast(Agent,{verbosity,Verbosity}).


%%%--------------------------------------------------

get_agent_mib_storage() ->
    ets:lookup_element(snmp_agent_table, agent_mib_storage, 2).

db(Tab) ->
    {Tab, get_agent_mib_storage()}.


%%%--------------------------------------------------
%%% 2. Main loop
%%%--------------------------------------------------
%% gen_server:reply(From, Reply)
handle_info({discovery_response, Response}, S) ->
    ?vdebug("handle_info(discovery_response) -> entry with"
	    "~n   Response: ~p", [Response]),    
    NewS = handle_discovery_response(S, Response),
    {noreply, NewS};
    
handle_info({snmp_pdu, Vsn, Pdu, PduMS, ACMData, Address, Extra}, S) ->
    ?vdebug("handle_info(snmp_pdu) -> entry with"
	    "~n   Vsn:     ~p"
	    "~n   Pdu:     ~p"
	    "~n   Address: ~p"
	    "~n   Extra:   ~p", [Vsn, Pdu, Address, Extra]),
    
    NewS = handle_snmp_pdu(is_valid_pdu_type(Pdu#pdu.type),
			   Vsn, Pdu, PduMS, ACMData, Address, Extra, S),

    {noreply, NewS};

handle_info(worker_available, S) ->
    ?vdebug("worker available",[]),
    {noreply, S#state{worker_state = ready}};

handle_info({send_notif, Notification, SendOpts}, S) ->
    ?vlog("[handle_info] send notif request:"
	  "~n   Notification:  ~p"
	  "~n   SendOpts:      ~p", 
	  [Notification, SendOpts]),
    case (catch handle_send_trap(S, Notification, SendOpts)) of
	{ok, NewS} ->
	    {noreply, NewS};
	{'EXIT', R} ->
	    ?vinfo("Trap not sent:~n   ~p", [R]),
	    {noreply, S};
	_ ->
	    {noreply, S}
    end;

%% <BACKWARD-COMPAT>
handle_info({send_trap, Trap, NotifyName, ContextName, Recv, Varbinds}, S) ->
    ?vlog("[handle_info] send trap request:"
	  "~n   Trap:          ~p"
	  "~n   NotifyName:    ~p"
	  "~n   ContextName:   ~p"
	  "~n   Recv:          ~p" 
	  "~n   Varbinds:      ~p", 
	  [Trap, NotifyName, ContextName, Recv, Varbinds]),
    ExtraInfo     = ?DEFAULT_NOTIF_EXTRA_INFO, 
    LocalEngineID = local_engine_id(S),
    case (catch handle_send_trap(S, Trap, NotifyName, ContextName,
				 Recv, Varbinds, LocalEngineID, ExtraInfo)) of
	{ok, NewS} ->
	    {noreply, NewS};
	{'EXIT', R} ->
	    ?vinfo("Trap not sent:~n   ~p", [R]),
	    {noreply, S};
	_ ->
	    {noreply, S}
    end;

handle_info({send_trap, Trap, NotifyName, ContextName, Recv, Varbinds, 
	     LocalEngineID}, S) ->
    ?vlog("[handle_info] send trap request:"
	  "~n   Trap:          ~p"
	  "~n   NotifyName:    ~p"
	  "~n   ContextName:   ~p"
	  "~n   Recv:          ~p" 
	  "~n   Varbinds:      ~p" 
	  "~n   LocalEngineID: ~p", 
	  [Trap, NotifyName, ContextName, Recv, Varbinds, LocalEngineID]),
    ExtraInfo = ?DEFAULT_NOTIF_EXTRA_INFO, 
    case (catch handle_send_trap(S, Trap, NotifyName, ContextName,
				 Recv, Varbinds, LocalEngineID, ExtraInfo)) of
	{ok, NewS} ->
	    {noreply, NewS};
	{'EXIT', R} ->
	    ?vinfo("Trap not sent:~n   ~p", [R]),
	    {noreply, S};
	_ ->
	    {noreply, S}
    end;
%% </BACKWARD-COMPAT>

handle_info({forward_trap, TrapRecord, NotifyName, ContextName, 
	     Recv, Varbinds, ExtraInfo}, S) ->
    ?vlog("[handle_info] forward trap request:"
	  "~n   TrapRecord:    ~p"
	  "~n   NotifyName:    ~p"
	  "~n   ContextName:   ~p"
	  "~n   Recv:          ~p"
	  "~n   Varbinds:      ~p", 
	  [TrapRecord, NotifyName, ContextName, Recv, Varbinds]),
    LocalEngineID = ?DEFAULT_LOCAL_ENGINE_ID, 
    case (catch maybe_send_trap(S, TrapRecord, NotifyName, ContextName,
				Recv, Varbinds, LocalEngineID, ExtraInfo)) of
	{ok, NewS} ->
	    {noreply, NewS};
	{'EXIT', R} ->
	    ?vinfo("Trap not sent:~n   ~p", [R]),
	    {noreply, S};
	_ ->
	    {noreply, S}
    end;

%% <BACKWARD-COMPAT>
handle_info({forward_trap, TrapRecord, NotifyName, ContextName, 
	     Recv, Varbinds}, S) ->
    ?vlog("[handle_info] forward trap request:"
	  "~n   TrapRecord:    ~p"
	  "~n   NotifyName:    ~p"
	  "~n   ContextName:   ~p"
	  "~n   Recv:          ~p"
	  "~n   Varbinds:      ~p", 
	  [TrapRecord, NotifyName, ContextName, Recv, Varbinds]),
    ExtraInfo     = ?DEFAULT_NOTIF_EXTRA_INFO, 
    LocalEngineID = ?DEFAULT_LOCAL_ENGINE_ID, 
    case (catch maybe_send_trap(S, TrapRecord, NotifyName, ContextName,
				Recv, Varbinds, LocalEngineID, ExtraInfo)) of
	{ok, NewS} ->
	    {noreply, NewS};
	{'EXIT', R} ->
	    ?vinfo("Trap not sent:~n   ~p", [R]),
	    {noreply, S};
	_ ->
	    {noreply, S}
    end;
%% </BACKWARD-COMPAT>

handle_info({backup_done, Reply}, #state{backup = {_, From}} = S) ->
    ?vlog("[handle_info] backup done:"
	  "~n   Reply: ~p", [Reply]),
    gen_server:reply(From, Reply),
    {noreply, S#state{backup = undefined}};


handle_info(invalidate_ca_cache, S) ->
    invalidate_ca_cache(),
    {noreply, S};


%%-----------------------------------------------------------------
%% If a process crashes, we first check to see if it was the mib,
%% net-if or note-store.
%% Otherwise, we check to see if it was a subagent. In this case
%% we unregister the sa, and unlink us from the sa.
%%-----------------------------------------------------------------
handle_info({'EXIT', Pid, Reason}, #state{note_store = Pid} = S) ->
    ?vlog("note store (~p) exited for reason ~n~p", [Pid, Reason]),
    error_msg("note-store exited: ~n~p", [Reason]),
    {stop, {note_store_exit, Reason}, S#state{note_store = undefined}};
handle_info({'EXIT', Pid, Reason}, #state{worker = Pid} = S) ->
    ?vlog("worker (~p) exited -> create new ~n   ~p", [Pid, Reason]),
    NewWorker = worker_start(), 
    {noreply, S#state{worker = NewWorker}};
handle_info({'EXIT', Pid, Reason}, #state{set_worker = Pid} = S) ->
    ?vlog("set-worker (~p) exited -> create new ~n   ~p", [Pid,Reason]),
    NewWorker = set_worker_start(), 
    {noreply, S#state{set_worker = NewWorker}};
handle_info({'EXIT', Pid, Reason}, #state{parent = Pid} = S) ->
    ?vlog("parent (~p) exited for reason ~n~p", [Pid,Reason]),
    {stop, {parent_died, Reason}, S};
handle_info({'EXIT', Pid, Reason}, #state{backup = {Pid, From}} = S) ->
    ?vlog("backup server (~p) exited for reason ~n~p", [Pid, Reason]),
    case Reason of
	normal ->
	    {noreply, S};
	_ ->
	    gen_server:reply(From, {error, Reason}),
	    {noreply, S#state{backup = undefined}}
    end;
handle_info({'EXIT', Pid, Reason}, S) ->
    ?vlog("~p exited for reason ~p", [Pid, Reason]),
    Mib   = get(mibserver),
    NetIf = get(net_if),
    case Pid of
	Mib ->
	    error_msg("mib-server exited: ~n~p", [Reason]),
	    {stop, {mib_server_exit, Reason}, S};
	NetIf ->
	    error_msg("net-if exited: ~n~p", [Reason]),
	    {stop, {net_if_exit, Reason}, S};
	_ ->
	    %% Could be a sub-agent
	    SAs = snmpa_mib:info(Mib, subagents),
	    case lists:keysearch(Pid, 1, SAs) of
		{value, _} ->
		    ?vlog("subagent exit", []),
		    snmpa_mib:unregister_subagent(Mib, Pid),
		    unlink(Pid);
		_ -> 
		    %% Otherwise it was probably a worker thread - ignore
		    ok
	    end,
	    {noreply, S}
    end;

handle_info({'DOWN', Ref, process, Pid, {mibs_cache_reply, Reply}}, 
	    #state{mibs_cache_request = {Pid, Ref, From}} = S) ->
    ?vlog("reply from the mibs cache request handler (~p): ~n~p", 
	  [Pid, Reply]),
    gen_server:reply(From, Reply),
    {noreply, S#state{mibs_cache_request = undefined}};

handle_info(Info, S) ->
    warning_msg("received unexpected info: ~n~p", [Info]),
    {noreply, S}.

handle_call(restart_worker, _From, #state{worker = Pid} = S) ->
    if 
	is_pid(Pid) ->
	    ?vlog("[handle_call] restart worker ~p", [Pid]),
	    exit(Pid, kill);
	true ->
	    ?vlog("[handle_call] not multi-threaded => "
		  "ignoring restart request", []),
	    ok
    end,
    {reply, ok, S};
handle_call(restart_set_worker, _From, #state{set_worker = Pid} = S) ->
    if
	is_pid(Pid) ->
	    ?vlog("[handle_call] restart set worker: ~p", [Pid]),
	    exit(Pid, kill);
	true ->
	    ?vlog("[handle_call] not multi-threaded => "
		  "ignoring restart request", []),
	    ok
    end,
    {reply, ok, S};

handle_call({send_notif, Notification, SendOpts}, _From, S) ->
    ?vlog("[handle_call] send notif request:"
	  "~n   Notification:  ~p"
	  "~n   SendOpts:      ~p", 
	  [Notification, SendOpts]),
    case (catch handle_send_trap(S, Notification, SendOpts)) of
	{ok, NewS} ->
	    {reply, ok, NewS};
	{'EXIT', Reason} ->
	    ?vinfo("Trap not sent:~n   ~p", [Reason]),
	    {reply, {error, {send_failed, Reason}}, S};
	_ ->
	    ?vinfo("Trap not sent", []),
	    {reply, {error, send_failed}, S}
    end;

%% <BACKWARD-COMPAT>
handle_call({send_trap, Trap, NotifyName, ContextName, Recv, Varbinds}, 
	    _From, S) ->
    ?vlog("[handle_call] send trap request:"
	  "~n   Trap:          ~p"
	  "~n   NotifyName:    ~p"
	  "~n   ContextName:   ~p"
	  "~n   Recv:          ~p" 
	  "~n   Varbinds:      ~p", 
	  [Trap, NotifyName, ContextName, Recv, Varbinds]),
    ExtraInfo     = ?DEFAULT_NOTIF_EXTRA_INFO, 
    LocalEngineID = local_engine_id(S),
    case (catch handle_send_trap(S, Trap, NotifyName, ContextName,
				 Recv, Varbinds, LocalEngineID, ExtraInfo)) of
	{ok, NewS} ->
	    {reply, ok, NewS};
	{'EXIT', Reason} ->
	    ?vinfo("Trap not sent:~n   ~p", [Reason]),
	    {reply, {error, {send_failed, Reason}}, S};
	_ ->
	    ?vinfo("Trap not sent", []),
	    {reply, {error, send_failed}, S}
    end;

handle_call({send_trap, Trap, NotifyName, 
	     ContextName, Recv, Varbinds, LocalEngineID}, 
	    _From, S) ->
    ?vlog("[handle_call] send trap request:"
	  "~n   Trap:          ~p"
	  "~n   NotifyName:    ~p"
	  "~n   ContextName:   ~p"
	  "~n   Recv:          ~p" 
	  "~n   Varbinds:      ~p" 
	  "~n   LocalEngineID: ~p", 
	  [Trap, NotifyName, ContextName, Recv, Varbinds, LocalEngineID]),
    ExtraInfo = ?DEFAULT_NOTIF_EXTRA_INFO, 
    case (catch handle_send_trap(S, Trap, NotifyName, ContextName,
				 Recv, Varbinds, LocalEngineID, ExtraInfo)) of
	{ok, NewS} ->
	    {reply, ok, NewS};
	{'EXIT', Reason} ->
	    ?vinfo("Trap not sent:~n   ~p", [Reason]),
	    {reply, {error, {send_failed, Reason}}, S};
	_ ->
	    ?vinfo("Trap not sent", []),
	    {reply, {error, send_failed}, S}
    end;
%% </BACKWARD-COMPAT>

handle_call({discovery, 
	     TargetName, Notification, ContextName, Vbs, DiscoHandler, 
	     ExtraInfo}, 
	    From, 
	    #state{disco = undefined} = S) ->
    ?vlog("[handle_call] initiate discovery process:"
	  "~n   TargetName:   ~p"
	  "~n   Notification: ~p"
	  "~n   ContextName:  ~p"
	  "~n   Vbs:          ~p"
	  "~n   DiscoHandler: ~p"
	  "~n   ExtraInfo:    ~p", 
	  [TargetName, Notification, ContextName, Vbs, 
	   DiscoHandler, ExtraInfo]),
    case handle_discovery(S, From, TargetName, 
			  Notification, ContextName, Vbs, DiscoHandler, 
			  ExtraInfo) of
	{ok, NewS} ->
	    ?vtrace("[handle_call] first stage of discovery process initiated",
		    []),
	    {noreply, NewS};
	{error, _} = Error ->
	    {reply, Error, S}
    end;
handle_call({discovery, _TargetName, _Notification, _ContextName, _Vbs, _DiscoHandler, _ExtraInfo}, _From, 
	    #state{disco = DiscoData} = S) ->
    Reply = {error, {discovery_in_progress, DiscoData}}, 
    {reply, Reply, S};
handle_call({subagent_get, Varbinds, PduData, IsNotification}, _From, S) ->
    ?vlog("[handle_call] subagent get:"
	  "~n   Varbinds: ~p"
	  "~n   PduData:  ~p", 
	  [Varbinds,PduData]),
    put_pdu_data(PduData),
    {reply, do_get(Varbinds, IsNotification), S};
handle_call({subagent_get_next, MibView, Varbinds, PduData}, _From, S) ->
    ?vlog("[handle_call] subagent get-next:"
	  "~n   MibView:  ~p"
	  "~n   Varbinds: ~p"
	  "~n   PduData:  ~p", 
	  [MibView,Varbinds,PduData]),
    put_pdu_data(PduData),
    {reply, do_get_next(MibView, Varbinds, infinity), S};
handle_call({subagent_set, Arguments, PduData}, _From, S) ->
    ?vlog("[handle_call] subagent set:"
	  "~n   Arguments: ~p"
	  "~n   PduData:   ~p", 
	  [Arguments,PduData]),
    put_pdu_data(PduData),
    {reply, do_subagent_set(Arguments), S};

handle_call({get, Vars, Context}, _From, S) ->
    ?vlog("[handle_call] get:"
	  "~n   Vars:    ~p"
	  "~n   Context: ~p", [Vars, Context]),
    put_pdu_data({undefined, undefined, undefined, undefined, Context}),
    case catch mapfoldl(fun ?MODULE:tr_var/2, [], 1, Vars) of
	{error, Reason} -> {reply, {error, Reason}, S};
	{_, Varbinds} ->
	    ?vdebug("Varbinds: ~p",[Varbinds]),
	    Reply =
		case do_get(Varbinds, false) of
		    {noError, 0, NewVarbinds} ->
			Vbs = lists:keysort(#varbind.org_index, NewVarbinds),
			[Value || #varbind{value = Value} <- Vbs];
		    {ErrorStatus, ErrIndex, _} ->
			N = lists:nth(ErrIndex, Vars),
			{error, {ErrorStatus, N}}
		end,
	    {reply, Reply, S}
    end;

handle_call({get_next, Vars, Context}, _From, S) ->
    ?vlog("[handle_call] get_next:"
          "~n   Vars:    ~p"
          "~n   Context: ~p",[Vars, Context]),
    put_pdu_data({undefined, undefined, undefined, undefined, Context}),
    case catch mapfoldl(fun ?MODULE:tr_var/2, [], 1, Vars) of
        {error, Reason} -> {reply, {error, Reason}, S};
        {_, Varbinds} ->
            ?vdebug("Varbinds: ~p",[Varbinds]),
            MibView = snmpa_acm:get_root_mib_view(),
            Reply =
                case do_get_next(MibView, Varbinds, infinity) of
                    {noError, 0, NewVarbinds} ->
                        Vbs = lists:keysort(#varbind.org_index, NewVarbinds),
			[{Oid,Val} || #varbind{oid = Oid, value = Val} <- Vbs];
                    {ErrorStatus, ErrIndex, _} ->
                        N = lists:nth(ErrIndex, Vars),
                        {error, {ErrorStatus, N}}
                end,
            {reply, Reply, S}
    end;

handle_call({do_get, MibView, UnsortedVarbinds, IsNotification, PduData}, 
	    _From, S) ->
    ?vlog("[handle_call] do_get:"
	  "~n   MibView:          ~p"
	  "~n   UnsortedVarbinds: ~p"
	  "~n   IsNotification:   ~p" 
	  "~n   PduData:          ~p", 
	  [MibView, UnsortedVarbinds, IsNotification, PduData]),
    put_pdu_data(PduData),
    Reply = do_get(MibView, UnsortedVarbinds, IsNotification),
    {reply, Reply, S};

handle_call({register_subagent, SubTreeOid, SubagentPid}, _From, S) ->
    Reply = 
	case snmpa_mib:register_subagent(get(mibserver),
					SubTreeOid, SubagentPid) of
	    ok -> link(SubagentPid), ok;
	    Error -> Error
	end,
    {reply, Reply, S};

handle_call({unregister_subagent, SubagentPid}, _From, S) 
  when is_pid(SubagentPid) ->
    ?vlog("[handle_call] unregister subagent ~p", [SubagentPid]),
    Reply = snmpa_mib:unregister_subagent(get(mibserver), SubagentPid),
    unlink(SubagentPid),
    {reply, Reply, S};

handle_call({unregister_subagent, SubTreeOid}, _From, S) ->
    ?vlog("[handle_call] unregister subagent ~p", [SubTreeOid]),
    Reply = 
	case snmpa_mib:unregister_subagent(get(mibserver), SubTreeOid) of
	    {ok, DeletedSubagentPid} ->
		SAs = snmpa_mib:info(get(mibserver), subagents),
		case lists:keysearch(DeletedSubagentPid, 1, SAs) of
		    {value, _} -> ok;
		    _ -> unlink(DeletedSubagentPid)
		end,
		ok;
	    Error ->
		Error
	end,
    {reply, Reply, S};

%% <BACKWARD-COMPAT>
handle_call({load_mibs, Mibs}, _From, S) ->
    ?vlog("load mibs ~p", [Mibs]),
    {reply, snmpa_mib:load_mibs(get(mibserver), Mibs), S};
%% </BACKWARD-COMPAT>

handle_call({load_mibs, Mibs, Force}, _From, S) ->
    ?vlog("[~w] load mibs ~p", [Force, Mibs]),
    {reply, snmpa_mib:load_mibs(get(mibserver), Mibs, Force), S};

%% <BACKWARD-COMPAT>
handle_call({unload_mibs, Mibs}, _From, S) ->
    ?vlog("unload mibs ~p", [Mibs]),
    {reply, snmpa_mib:unload_mibs(get(mibserver), Mibs), S};
%% </BACKWARD-COMPAT>

handle_call({unload_mibs, Mibs, Force}, _From, S) ->
    ?vlog("[~w] unload mibs ~p", [Force, Mibs]),
    {reply, snmpa_mib:unload_mibs(get(mibserver), Mibs, Force), S};

handle_call(which_mibs, _From, S) ->
    ?vlog("which mibs", []),
    {reply, snmpa_mib:which_mibs(get(mibserver)), S};

handle_call({whereis_mib, Mib}, _From, S) ->
    ?vlog("whereis mib ~p", [Mib]),
    {reply, snmpa_mib:whereis_mib(get(mibserver), Mib), S};

handle_call({mibs_cache_request, MibsCacheReq}, From, S) ->
    ?vlog("mibs_cache_request: ~p", [MibsCacheReq]),
    {MibsCacheWorker, Ref} = 
	handle_mibs_cache_request(get(mibserver), MibsCacheReq),
    NewS = S#state{mibs_cache_request = {MibsCacheWorker, Ref, From}},
    {noreply, NewS};

handle_call(info, _From, S) ->
    ?vlog("info", []),
    Vsns  = S#state.vsns,
    Stats = get_stats_counters(), 
    AI    = agent_info(S),
    NI    = net_if_info(S),
    NS    = note_store_info(S),
    SS    = symbolic_store_info(),
    LD    = local_db_info(),
    MS    = mib_server_info(), 
    Info  = [{vsns,           Vsns}, 
	     {stats_counters, Stats},
	     {agent,          AI}, 
	     {net_if,         NI}, 
	     {note_store,     NS},
	     {symbolic_store, SS},
	     {local_db,       LD},
	     {mib_server,     MS}], 
    {reply, Info, S};

handle_call(get_net_if, _From, S) ->
    {reply, get(net_if), S};

%% Only accept a backup request if there is none already in progress
handle_call({backup, BackupDir}, From, #state{backup = undefined} = S) ->
    ?vlog("backup: ~p", [BackupDir]),
    Pid = self(),
    V   = get(verbosity),
    MS  = get(mibserver),
    BackupServer = 
	erlang:spawn_link(
	  fun() ->
		  put(sname, abs),
		  put(verbosity, V),
		  Dir   = filename:join([BackupDir]),
		  Reply = handle_backup(Dir, MS),
		  Pid ! {backup_done, Reply},
		  unlink(Pid)
	  end),
    ?vtrace("backup server: ~p", [BackupServer]),
    {noreply, S#state{backup = {BackupServer, From}}};

handle_call({backup, _BackupDir}, _From, #state{backup = Backup} = S) ->
    ?vinfo("backup already in progress: ~p", [Backup]),
    {reply, {error, backup_in_progress}, S};

handle_call(dump_mibs, _From, S) ->
    Reply = snmpa_mib:dump(get(mibserver)),
    {reply, Reply, S};
    
handle_call({dump_mibs,File}, _From, S) ->
    Reply = snmpa_mib:dump(get(mibserver),File),
    {reply, Reply, S};
    
handle_call({register_notification_filter, Id, Mod, Data, Where}, _From, 
	    #state{nfilters = NFs} = S) ->
    ?vlog("register_notification_filter -> "
	  "~n   Id:    ~p"
	  "~n   Mod:   ~p"
	  "~n   Where: ~p", [Id, Mod, Where]),
    case lists:keymember(Id, 2, NFs) of
	true ->
	    {reply, {error, {already_registered, Id}}, S};
	false ->
	    NF = #notification_filter{id = Id, mod = Mod, data = Data},
	    {Reply, NewNFs} = add_notification_filter(Where, NF, NFs),
	    {reply, Reply, S#state{nfilters = NewNFs}}
    end;

handle_call({unregister_notification_filter, Id}, _From, 
	    #state{nfilters = NFs} = S) ->
    ?vlog("unregister_notification_filter -> "
	  "~n   Id: ~p", [Id]),
    case lists:keydelete(Id, 2, NFs) of
	NFs ->
	    {reply, {error, {not_found, Id}}, S};
	NFs2 ->
	    {reply, ok, S#state{nfilters = NFs2}}
    end;

handle_call(which_notification_filter, _From, 
	    #state{nfilters = NFs} = S) ->
    ?vlog("which_notification_filter", []),
    {reply, [Id || #notification_filter{id = Id} <- NFs], S};

handle_call({mib_of, Oid}, _From, S) ->
    Reply = handle_mib_of(get(mibserver), Oid),
    {reply, Reply, S};

handle_call({me_of, Oid}, _From, S) ->
    Reply = handle_me_of(get(mibserver), Oid),
    {reply, Reply, S};

handle_call(get_log_type, _From, S) ->
    ?vlog("handle_call(get_log_type) -> entry with", []),
    Reply = handle_get_log_type(S), 
    {reply, Reply, S};
    
handle_call({set_log_type, NewType}, _From, S) ->
    ?vlog("handle_call(set_log_type) -> entry with"
	  "~n   NewType: ~p", [NewType]),
    Reply = handle_set_log_type(S, NewType), 
    {reply, Reply, S};
    
handle_call(get_request_limit, _From, S) ->
    ?vlog("handle_call(get_request_limit) -> entry with", []),
    Reply = handle_get_request_limit(S), 
    {reply, Reply, S};
    
handle_call({set_request_limit, NewLimit}, _From, S) ->
    ?vlog("handle_call(set_request_limit) -> entry with"
	  "~n   NewLimit: ~p", [NewLimit]),
    Reply = handle_set_request_limit(S, NewLimit), 
    {reply, Reply, S};

handle_call(stop, _From, S) ->
    {stop, normal, ok, S};

handle_call(Req, _From, S) ->
    warning_msg("received unknown request: ~n~p", [Req]),
    Reply = {error, {unknown, Req}}, 
    {reply, Reply, S}.
    
handle_cast({verbosity, Verbosity}, S) ->
    ?vlog("verbosity: ~p -> ~p",[get(verbosity), Verbosity]),
    put(verbosity,snmp_verbosity:validate(Verbosity)),
    case S#state.worker of
	Pid when is_pid(Pid) -> Pid ! ?mk_verbosity_wreq(Verbosity);
	_ -> ok
    end,
    case S#state.set_worker of
	Pid2 when is_pid(Pid2) -> Pid2 ! ?mk_verbosity_wreq(Verbosity);
	_ -> ok
    end,
    {noreply, S};
    
handle_cast({sub_agents_verbosity,Verbosity}, S) ->
    ?vlog("sub_agents verbosity: ~p",[Verbosity]),
    subagents_verbosity(Verbosity),
    {noreply, S};
    
%% This should only happen if we are a master_agent
handle_cast({net_if_verbosity, Verbosity}, S) ->
    net_if_verbosity(get(net_if), Verbosity),
    {noreply, S};
    
handle_cast({mib_server_verbosity, Verbosity}, S) ->
    mib_server_verbosity(get(mibserver),Verbosity),
    {noreply, S};
    
handle_cast({note_store_verbosity, Verbosity}, #state{note_store = Pid} = S) ->
    note_store_verbosity(Pid,Verbosity),
    {noreply, S};
    
handle_cast(Msg, S) ->
    warning_msg("received unknown message: ~n~p", [Msg]),
    {noreply, S}.

    
terminate(shutdown, #state{worker     = Worker,
			   set_worker = SetWorker,
			   backup     = Backup, 
			   ref = Ref}) ->
    %% Ordered shutdown - stop misc-workers, net_if, mib-server and note-store.
    backup_server_stop(Backup), 
    worker_stop(Worker, 100),
    worker_stop(SetWorker, 100),
    snmpa_misc_sup:stop_net_if(Ref), 
    snmpa_misc_sup:stop_mib_server(Ref);
terminate(_Reason, _S) ->
    %% We crashed!  We will reuse net_if and mib if we get restarted.
    ok.


handle_mibs_cache_request(MibServer, Req) ->
    {MibsCacheWorker, MibsCacheRef} = 
	spawn_monitor(
	  fun() -> 
		  Reply = 
		      case Req of
			  invalidate_cache ->
			      snmpa_mib:invalidate_cache(MibServer);
			  gc_cache ->
			      snmpa_mib:gc_cache(MibServer);
			  {gc_cache, Age} ->
			      snmpa_mib:gc_cache(MibServer, Age);
			  {gc_cache, Age, GcLimit} ->
			      snmpa_mib:gc_cache(MibServer, Age, GcLimit);
			  cache_size ->
			      snmpa_mib:which_cache_size(MibServer);
			  enable_cache ->
			      snmpa_mib:enable_cache(MibServer);
			  disable_cache ->
			      snmpa_mib:disable_cache(MibServer);
			  enable_autogc ->
			      snmpa_mib:enable_cache_autogc(MibServer);
			  disable_autogc ->
			      snmpa_mib:disable_cache_autogc(MibServer);
			  {update_gclimit, GcLimit} ->
			      snmpa_mib:update_cache_gclimit(MibServer, 
							      GcLimit);
			  {update_age, Age} ->
			      snmpa_mib:update_cache_age(MibServer, Age);
			  _ ->
			      {error, {unknown_mibs_cache_request, Req}}
		      end,
		  exit({mibs_cache_reply, Reply})
	  end),
    {MibsCacheWorker, MibsCacheRef}.

		        
%%-----------------------------------------------------------------
%% Code replacement
%% 
%%-----------------------------------------------------------------

%% Downgrade
%%
%% code_change({down, _Vsn}, S1, downgrade_to_pre_4_17_3) ->
%%     #state{type               = Type, 
%% 	   parent             = Parent, 
%% 	   worker             = Worker, 
%% 	   worker_state       = WorkerState,
%% 	   set_worker         = SetWorker, 
%% 	   multi_threaded     = MT, 
%% 	   ref                = Ref, 
%% 	   vsns               = Vsns,
%% 	   nfilters           = NF,
%% 	   note_store         = NoteStore,
%% 	   mib_server         = MS, 
%% 	   net_if             = NetIf, 
%% 	   net_if_mod         = NetIfMod, 
%% 	   backup             = Backup,
%% 	   disco              = Disco,
%% 	   mibs_cache_request = MCR} = S1, 
%%     S2 = {state, 
%% 	  type               = Type, 
%% 	  parent             = Parent, 
%% 	  worker             = Worker, 
%% 	  worker_state       = WorkerState,
%% 	  set_worker         = SetWorker, 
%% 	  multi_threaded     = MT, 
%% 	  ref                = Ref, 
%% 	  vsns               = Vsns,
%% 	  nfilters           = NF,
%% 	  note_store         = NoteStore,
%% 	  mib_server         = MS, 
%% 	  net_if             = NetIf, 
%% 	  net_if_mod         = NetIfMod, 
%% 	  backup             = Backup,
%% 	  disco              = Disco,
%% 	  mibs_cache_request = MCR}, 
%%     {ok, S2};

%% %% Upgrade
%% %%
%% code_change(_Vsn, S1, upgrade_from_pre_4_17_3) ->
%%     {state, 
%%      type               = Type, 
%%      parent             = Parent, 
%%      worker             = Worker, 
%%      worker_state       = WorkerState,
%%      set_worker         = SetWorker, 
%%      multi_threaded     = MT, 
%%      ref                = Ref, 
%%      vsns               = Vsns,
%%      nfilters           = NF,
%%      note_store         = NoteStore,
%%      mib_server         = MS, 
%%      net_if             = NetIf, 
%%      net_if_mod         = NetIfMod, 
%%      backup             = Backup,
%%      disco              = Disco,
%%      mibs_cache_request = MCR} = S1,
%%     S2 = #state{type               = Type, 
%% 		parent             = Parent, 
%% 		worker             = Worker, 
%% 		worker_state       = WorkerState,
%% 		set_worker         = SetWorker, 
%% 		multi_threaded     = MT, 
%% 		ref                = Ref, 
%% 		vsns               = Vsns,
%% 		nfilters           = NF,
%% 		note_store         = NoteStore,
%% 		mib_server         = MS, 
%% 		net_if             = NetIf, 
%% 		net_if_mod         = NetIfMod, 
%% 		backup             = Backup,
%% 		disco              = Disco,
%% 		mibs_cache_request = MCR,
%% 		gb_max_vbs         = ?DEFAULT_GB_MAX_VBS}, 
%%     {ok, S2};

code_change(_Vsn, S, _Extra) ->
    {ok, S}.


%% workers_restart(#state{worker = W, set_worker = SW} = S) ->
%%     Worker    = worker_restart(W),
%%     SetWorker = set_worker_restart(SW),
%%     S#state{worker     = Worker, 
%% 	    set_worker = SetWorker}.


%%-----------------------------------------------------------------

backup_server_stop({Pid, _}) when is_pid(Pid) ->
    exit(Pid, kill);
backup_server_stop(_) ->
    ok.


workers_start(true) ->
    ?vdebug("start worker and set-worker",[]),
    {worker_start(), set_worker_start()};
workers_start(_) ->
    {undefined, undefined}.

worker_start() ->
    worker_start(get()).

set_worker_start() ->
    worker_start([{master, self()} | get()]).

worker_start(Dict) ->
    proc_lib:spawn_link(?MODULE, worker, [self(), Dict]).

%% worker_stop(Pid) ->
%%     worker_stop(Pid, infinity).

worker_stop(Pid, Timeout) when is_pid(Pid) ->
    Pid ! ?mk_terminate_wreq(), 
    receive 
	{'EXIT', Pid, normal} ->
	    ok
    after Timeout ->
	    (catch exit(Pid, kill)),
	    ok
    end;
worker_stop(_, _) ->
    ok.

%% set_worker_restart(Pid) ->
%%     worker_restart(Pid, [{master, self()} | get()]).

%% worker_restart(Pid) ->
%%     worker_restart(Pid, get()).

%% worker_restart(Pid, Dict) when is_pid(Pid) -> 
%%     worker_stop(Pid),
%%     worker_start(Dict);
%% worker_restart(Any, _Dict) ->
%%     Any.


%%-----------------------------------------------------------------

handle_backup(BackupDir, MibServer) ->
    ?vlog("handle_backup -> entry with"
	  "~n   BackupDir: ~p", [BackupDir]),
    case ets:lookup(snmp_agent_table, db_dir) of
	[{db_dir, BackupDir}] ->
	    ?vinfo("handle_backup -> backup dir and db dir the same", []),
	    {error, db_dir};
	_ ->
	    case file:read_file_info(BackupDir) of
		{ok, #file_info{type = directory}} ->
		    ?vdebug("handle_backup -> backup dir ok", []),

		    VacmRes = (catch snmpa_vacm:backup(BackupDir)),
		    ?vtrace("handle_backup -> "
			    "~n   VacmRes: ~p", [VacmRes]),

		    LdbRes  = (catch snmpa_local_db:backup(BackupDir)),
		    ?vtrace("handle_backup -> "
			    "~n   LdbRes: ~p", [LdbRes]),

		    MsRes   = (catch snmpa_mib:backup(MibServer, BackupDir)),
		    ?vtrace("handle_backup -> "
			    "~n   MsRes: ~p", [MsRes]),

		    SsRes   = (catch snmpa_symbolic_store:backup(BackupDir)),
		    ?vtrace("handle_backup -> "
			    "~n   SsRes: ~p", [SsRes]),
		    handle_backup_res([{vacm,           VacmRes}, 
				       {local_db,       LdbRes},
				       {mib_server,     MsRes},
				       {symbolic_store, SsRes}]);
		{ok, _} ->
		    ?vinfo("handle_backup -> backup dir not a dir", []),
		    {error, not_a_directory};
		Error ->
		    ?vinfo("handle_backup -> Error: ~p", [Error]),
		    Error
	    end
    end.


handle_backup_res(Results) ->
    handle_backup_res(Results, []).

handle_backup_res([], []) ->
    ok;
handle_backup_res([], Acc) ->
    {error, lists:reverse(Acc)};
handle_backup_res([{_, ok}|Results], Acc) ->
    handle_backup_res(Results, Acc);
handle_backup_res([{Who, {error, Reason}}|Results], Acc) ->
    handle_backup_res(Results, [{Who, Reason}|Acc]);
handle_backup_res([{Who, Crap}|Results], Acc) ->
    handle_backup_res(Results, [{Who, Crap}|Acc]).


%%-----------------------------------------------------------------
%% We must cheat to get the community string out of the ACM data,
%% because we (for some reason) support the function
%% snmpa:current_community().
%%-----------------------------------------------------------------
cheat({community, _SecModel, Community, _TAddress}, Address, ContextName) ->
    {Community, Address, ContextName};
cheat({community, _SecModel, Community, _TDomain, _TAddress}, 
      Address, ContextName) ->
    {Community, Address, ContextName};
cheat(_, Address, ContextName) ->
    {"", Address, ContextName}.


%% This function will either be in the context of the:
%% 1) master-agent
%% 2) set-worker
%% 3) user code 
%%    ( calling e.g. snmp_community_mib:snmpCommunityTable(set, ...) )
invalidate_ca_cache() ->
    case get(master) of
        undefined -> % 1 or 3
            case get(auth_module) of
		undefined -> % 3
		    %% Ouch, we are not running in the context of the 
		    %% master agent either. Check if we are on the 
		    %% master-agent node. If so, sent it there,
		    case whereis(snmp_master_agent) of
			MasterAgent when is_pid(MasterAgent) ->
			    case node(MasterAgent) =:= node() of
				true ->
				    %% Ok, we are on the node running the
				    %% master_agent process, so sent it there
				    MasterAgent ! invalidate_ca_cache;
				false ->
				    %% This is running on a sub-agent node, 
				    %% so skip it
				    ok
			    end;
			_ -> % Not on this node 
			    ok
		    end;
		AuthMod -> % 1
		    AuthMod:invalidate_ca_cache()
	    end;
        Pid -> % 2
            Pid ! invalidate_ca_cache
    end.


%%-----------------------------------------------------------------
%% Threads and workers
%% 
%%-----------------------------------------------------------------

%% This functions spawns a temporary worker process, 
%% that evaluates one request and then silently exits. 
spawn_thread(Vsn, Pdu, PduMS, ACMData, Address, GbMaxVBs, Extra) ->
    Dict = get(),
    Args = [Vsn, Pdu, PduMS, ACMData, Address, GbMaxVBs, Extra, Dict], 
    proc_lib:spawn_link(?MODULE, handle_pdu, Args).

spawn_trap_thread(TrapRec, NotifyName, ContextName, Recv, Vbs, 
		  LocalEngineID, ExtraInfo) ->
    Dict = get(),
    proc_lib:spawn_link(?MODULE, do_send_trap,
			[TrapRec, NotifyName, ContextName, 
			 Recv, Vbs, LocalEngineID, ExtraInfo, Dict]).

do_send_trap(TrapRec, NotifyName, ContextName, Recv, Vbs, 
	     LocalEngineID, Dict) ->
    ExtraInfo = ?DEFAULT_NOTIF_EXTRA_INFO, 
    do_send_trap(TrapRec, NotifyName, ContextName, Recv, Vbs, 
		 LocalEngineID, ExtraInfo, Dict).
do_send_trap(TrapRec, NotifyName, ContextName, Recv, Vbs, 
	     LocalEngineID, ExtraInfo, Dict) ->
    lists:foreach(fun({Key, Val}) -> put(Key, Val) end, Dict),
    put(sname, trap_sender_short_name(get(sname))),
    ?vlog("starting",[]),
    snmpa_trap:send_trap(TrapRec, NotifyName, ContextName, Recv, Vbs, 
			 LocalEngineID, ExtraInfo, get(net_if)).

worker(Master, Dict) ->
    lists:foreach(fun({Key, Val}) -> put(Key, Val) end, Dict),
    put(sname, worker_short_name(get(sname))),
    ?vlog("starting",[]),
    worker_loop(Master).

worker_loop(Master) ->
    Res = 
	receive
	    #wrequest{cmd  = handle_pdu, 
		      info = Info} = Req ->
		?vtrace("worker_loop -> received handle_pdu request with"
			"~n   Info: ~p", [Info]),
		Vsn      = proplists:get_value(vsn,        Info),
		Pdu      = proplists:get_value(pdu,        Info),
		PduMS    = proplists:get_value(pdu_ms,     Info),
		ACMData  = proplists:get_value(acm_data,   Info),
		Address  = proplists:get_value(addr,       Info),
		GbMaxVBs = proplists:get_value(gb_max_vbs, Info),
		Extra    = proplists:get_value(extra,      Info),
		HandlePduRes = 
		    try 
			begin
			    handle_pdu2(Vsn, Pdu, PduMS, ACMData, Address, 
					GbMaxVBs, Extra)
			end
		    catch 
			T:E ->
			    exit({worker_crash, Req, T, E, 
				  erlang:get_stacktrace()})
		    end,
		Master ! worker_available,
		HandlePduRes; % For debugging...
	    
	    
	    #wrequest{cmd  = send_trap, 
		      info = Info} = Req ->
		?vtrace("worker_loop -> received send_trap request with"
			"~n   Info: ~p", [Info]),
		TrapRec       = proplists:get_value(trap_rec,        Info),
		NotifyName    = proplists:get_value(notify_name,     Info),
		ContextName   = proplists:get_value(context_name,    Info),
		Recv          = proplists:get_value(receiver,        Info),
		Vbs           = proplists:get_value(varbinds,        Info),
		LocalEngineID = proplists:get_value(local_engine_id, Info),
		Extra         = proplists:get_value(extra,           Info),
		SendTrapRes = 
		    try
			begin
			    snmpa_trap:send_trap(TrapRec, NotifyName, 
						 ContextName, Recv, Vbs, 
						 LocalEngineID, Extra, 
						 get(net_if))
			end
		    catch 
			T:E ->
			    exit({worker_crash, Req, T, E, 
				  erlang:get_stacktrace()})
		    end,
		Master ! worker_available, 
		SendTrapRes; % For debugging...
	    
	    
	    #wrequest{cmd  = verbosity, 
		      info = Info} ->
		Verbosity = proplists:get_value(verbosity, Info),
		put(verbosity, snmp_verbosity:validate(Verbosity));
	    
	    
	    #wrequest{cmd  = terminate} ->
		?vtrace("worker_loop -> received terminate request", []),
		exit(normal);
	    
	    
	    %% *************************************************************
	    %% 
	    %%         Kept for backward compatibillity reasons
	    %% 
	    %% *************************************************************
	    
	    {Vsn, Pdu, PduMS, ACMData, Address, Extra} ->
		?vtrace("worker_loop -> received request", []),
		handle_pdu2(Vsn, Pdu, PduMS, ACMData, Address, 
			    ?DEFAULT_GB_MAX_VBS, Extra),
		Master ! worker_available;
	    
	    %% We don't trap exits!
	    {TrapRec, NotifyName, ContextName, Recv, Vbs} -> 
		?vtrace("worker_loop -> send trap:"
			"~n   ~p", [TrapRec]),
		snmpa_trap:send_trap(TrapRec, NotifyName, 
				     ContextName, Recv, Vbs, get(net_if)),
		Master ! worker_available;
	    
	    %% We don't trap exits!
	    {send_trap, 
	     TrapRec, NotifyName, ContextName, Recv, Vbs, LocalEngineID,
	     ExtraInfo} -> 
		?vtrace("worker_loop -> send trap:"
			"~n   ~p", [TrapRec]),
		snmpa_trap:send_trap(TrapRec, NotifyName, 
				     ContextName, Recv, Vbs, 
				     LocalEngineID, ExtraInfo, 
				     get(net_if)),
		Master ! worker_available;
	    
	    {verbosity, Verbosity} ->
		put(verbosity, snmp_verbosity:validate(Verbosity));
	    
	    terminate ->
		exit(normal);
	    
	    _X ->
		%% ignore
		ignore_unknown
	
	after 30000 ->
		%% This is to assure that the worker process leaves a
		%% possibly old version of this module.
		ok
	end,
    ?vtrace("worker_loop -> wrap with"
	    "~n   ~p", [Res]),
    ?MODULE:worker_loop(Master).


%%-----------------------------------------------------------------
%%-----------------------------------------------------------------

handle_snmp_pdu(true, Vsn, Pdu, PduMS, ACMData, Address, Extra, 
		#state{multi_threaded = false, 
		       gb_max_vbs     = GbMaxVBs} = S) ->
    ?vtrace("handle_snmp_pdu -> single-thread agent",[]),
    handle_pdu2(Vsn, Pdu, PduMS, ACMData, Address, GbMaxVBs, Extra),
    S;
handle_snmp_pdu(true, Vsn, #pdu{type = 'set-request'} = Pdu, PduMS, 
		ACMData, Address, Extra, 
		#state{set_worker = Worker} = S) ->
    ?vtrace("handle_snmp_pdu -> multi-thread agent: "
	    "send set-request to main worker",[]),
    WRequest = ?mk_pdu_wreq(Vsn, Pdu, PduMS, ACMData, Address, infinity, Extra),
    Worker ! WRequest, 
    S#state{worker_state = busy};
handle_snmp_pdu(true, Vsn, Pdu, PduMS, 
		ACMData, Address, Extra, 
		#state{worker_state = busy, 
		       gb_max_vbs   = GbMaxVBs} = S) ->
    ?vtrace("handle_snmp_pdu -> multi-thread agent: "
	    "main worker busy - create new worker",[]),
    spawn_thread(Vsn, Pdu, PduMS, ACMData, Address, GbMaxVBs, Extra),
    S;
handle_snmp_pdu(true, Vsn, Pdu, PduMS, ACMData, Address, Extra, 
		#state{worker     = Worker, 
		       gb_max_vbs = GbMaxVBs} = S) ->
    ?vtrace("handle_snmp_pdu -> multi-thread agent: "
	    "send to main worker",[]),
    WRequest = ?mk_pdu_wreq(Vsn, Pdu, PduMS, ACMData, Address, GbMaxVBs, Extra),
    Worker ! WRequest, 
    S#state{worker_state = busy};
handle_snmp_pdu(_, _Vsn, _Pdu, _PduMS, _ACMData, _Address, _Extra, S) ->
    S.


%% Called via the spawn_thread function
%% <BACKWARD-COMPAT>
handle_pdu(Vsn, Pdu, PduMS, ACMData, Address, Extra, Dict) ->
    handle_pdu(Vsn, Pdu, PduMS, ACMData, Address, ?DEFAULT_GB_MAX_VBS, Extra, 
	       Dict).
%% </BACKWARD-COMPAT>
handle_pdu(Vsn, Pdu, PduMS, ACMData, Address, GbMaxVBs, Extra, Dict) ->
    lists:foreach(fun({Key, Val}) -> put(Key, Val) end, Dict),
    put(sname, pdu_handler_short_name(get(sname))),
    ?vlog("new worker starting",[]),
    handle_pdu2(Vsn, Pdu, PduMS, ACMData, Address, GbMaxVBs, Extra).

handle_pdu2(Vsn, Pdu, PduMS, ACMData, Address, GbMaxVBs, Extra) ->
    %% OTP-3324
    AuthMod = get(auth_module),
    case AuthMod:init_check_access(Pdu, ACMData) of
	{ok, MibView, ContextName} ->
	    ?vlog("handle_pdu -> ok:"
		  "~n   MibView:     ~p"
		  "~n   ContextName: ~p", [MibView, ContextName]),
	    AgentData = cheat(ACMData, Address, ContextName),
	    do_handle_pdu(MibView, Vsn, Pdu, PduMS, ACMData, AgentData, 
			  GbMaxVBs, Extra);
	{error, Reason} ->
	    ?vlog("handle_pdu -> error:"
		  "~n   Reason: ~p", [Reason]),
	    handle_acm_error(Vsn, Reason, Pdu, ACMData, Address, Extra);
	{discarded, Variable, Reason} ->
	    ?vlog("handle_pdu -> discarded:"
		  "~n   Variable: ~p"
		  "~n   Reason:   ~p", [Variable, Reason]),
	    get(net_if) ! {discarded_pdu, Vsn, Pdu#pdu.request_id,
			   ACMData, Variable, Extra}
    end.

do_handle_pdu(MibView, Vsn, Pdu, PduMS, 
	      ACMData, {Community, Address, ContextName}, 
	      GbMaxVBs, Extra) ->
    
    put(net_if_data, Extra),

    RePdu = process_msg(MibView, Vsn, Pdu, PduMS, Community, 
			Address, ContextName, GbMaxVBs),

    ?vtrace("do_handle_pdu -> processed:"
	    "~n   RePdu: ~p", [RePdu]),
    NetIf = get(net_if), 
    NetIf ! {snmp_response, Vsn, RePdu, 
	     RePdu#pdu.type, ACMData, Address, Extra}.


handle_acm_error(Vsn, Reason, Pdu, ACMData, Address, Extra) ->
    #pdu{type = Type, request_id = ReqId, varbinds = Vbs} = Pdu,
    RawErrStatus = snmpa_acm:error2status(Reason),
    case is_valid_pdu_type(Type) of
	true ->
	    %% RawErrStatus can be authorizationError or genErr.  If it is
	    %% authorizationError, we'll have to do different things, 
	    %% depending on which SNMP version is used.
	    %% v1 - noSuchName error
	    %% v2 - GET: all variables 'noSuchObject'
	    %%      NEXT/BULK: all variables 'endOfMibView'
	    %%      SET: noAccess error
	    %% v3 - authorizationError error
	    %%
	    %% NOTE: this procedure is not yet defined in the coex document!
	    ?vdebug("~n   Raw error status: ~w",[RawErrStatus]),
	    Idx = case Vbs of
		      [] -> 0;
		      _ -> 1
		  end,
	    RePdu =
		if
		    Vsn =:= 'version-1' ->
			ErrStatus = v2err_to_v1err(RawErrStatus),
			make_response_pdu(ReqId, ErrStatus, Idx, Vbs, Vbs);
		    Vsn =:= 'version-3' ->
			make_response_pdu(ReqId, RawErrStatus, Idx, Vbs, Vbs);
		    Type =:= 'get-request' ->  % this is v2
			ReVbs = lists:map(
				  fun(Vb) -> 
					  Vb#varbind{value=noSuchObject} 
				  end,
				  Vbs),
			make_response_pdu(ReqId, noError, 0, Vbs, ReVbs);
		    Type =:= 'set-request' ->
			make_response_pdu(ReqId, noAccess, Idx, Vbs, Vbs);
		    true -> % next or bulk
			ReVbs = lists:map(
				  fun(Vb) -> 
					  Vb#varbind{value=endOfMibView} 
				  end,
				  Vbs),
			make_response_pdu(ReqId, noError, 0, Vbs, ReVbs)
		end,
	    get(net_if) ! {snmp_response, Vsn, RePdu, 
			   'get-response', ACMData, Address, Extra};
	false ->
	    ?vdebug("~n   Raw error status: ~w"
		    "~n   invalid pdu type: ~w", 
		    [RawErrStatus,Type]),
	    ok
    end.

get_send_opt(Key, Default, SendOpts) ->
    case lists:keysearch(Key, 1, SendOpts) of
	{value, {Key, Value}} ->
	    Value;
	false ->
	    Default
    end.

handle_send_trap(S, Notification, SendOpts) ->
    NotifyName    = get_send_opt(name,     "",                        SendOpts),
    ContextName   = get_send_opt(context,  "",                        SendOpts),
    Recv          = get_send_opt(receiver, no_receiver,               SendOpts),
    Varbinds      = get_send_opt(varbinds, [],                        SendOpts),
    ExtraInfo     = get_send_opt(extra,    ?DEFAULT_NOTIF_EXTRA_INFO, SendOpts),
    LocalEngineID = 
	case lists:keysearch(local_engine_id, 1, SendOpts) of
	    {value, {local_engine_id, Value}} ->
		Value;
	    false ->
		local_engine_id(S)
	end,
    handle_send_trap(S, Notification, NotifyName, ContextName, Recv, Varbinds, 
		     LocalEngineID, ExtraInfo).

handle_send_trap(#state{type = Type} = S, 
		 Notification, NotifyName, ContextName, Recv, Varbinds, 
		 LocalEngineID, ExtraInfo) ->
    ?vtrace("handle_send_trap -> entry with"
	    "~n   Agent type:    ~p"
	    "~n   TrapName:      ~p"
	    "~n   NotifyName:    ~p"
	    "~n   ContextName:   ~p"
	    "~n   LocalEngineID: ~p", 
	    [Type, Notification, NotifyName, ContextName, LocalEngineID]),
    case snmpa_trap:construct_trap(Notification, Varbinds) of
	{ok, TrapRecord, VarList} ->
	    ?vtrace("handle_send_trap -> construction complete: "
		    "~n   TrapRecord: ~p"
		    "~n   VarList: ~p",
		    [TrapRecord, VarList]),
	    case Type of
		subagent ->
		    ?vtrace("handle_send_trap -> [sub] forward trap",[]),
		    maybe_forward_trap(S, TrapRecord, NotifyName,
				       ContextName, Recv, VarList, ExtraInfo),
		    {ok, S};
		master_agent ->
		    ?vtrace("handle_send_trap -> "
			    "[master] handle send trap",[]),
		    maybe_send_trap(S, TrapRecord, NotifyName,
				    ContextName, Recv, VarList,
				    LocalEngineID, ExtraInfo)
	    end;
	error ->
	    error
    end.
				

maybe_forward_trap(#state{parent = Parent, nfilters = NFs} = S,
		   TrapRec, NotifyName, ContextName, Recv, V, ExtraInfo) ->
    ?vtrace("maybe_forward_trap -> entry with"
	    "~n   NFs: ~p", [NFs]),
    case filter_notification(NFs, [], TrapRec) of
	{dont_send, [], Id} ->
	    ?vdebug("trap not forwarded [filter ~p]", [Id]),
	    {ok, S};
	
	{dont_send, Removed, Id} ->
	    ?vdebug("trap not forwarded [filter ~p]", [Id]),
	    NFs2 = del_notification_filter(Removed, NFs),
	    {ok, S#state{nfilters = NFs2}};
	
	{send, [], TrapRec2} ->
	    ?vtrace("maybe_forward_trap -> forward trap:"
		    "~n   ~p", [TrapRec2]),
	    forward_trap(Parent, TrapRec2, NotifyName, ContextName, Recv, V, 
			 ExtraInfo),
	    {ok, S};
	
	{send, Removed, TrapRec2} ->
	    ?vtrace("maybe_forward_trap -> forward trap:"
		    "~n   ~p", [TrapRec2]),
	    forward_trap(Parent, TrapRec2, NotifyName, ContextName, Recv, V, 
			 ExtraInfo),
	    NFs2 = del_notification_filter(Removed, NFs),
	    {ok, S#state{nfilters = NFs2}}
    end.


maybe_send_trap(#state{nfilters = NFs} = S, 
		TrapRec, NotifyName, ContextName, Recv, Varbinds, 
		LocalEngineID, ExtraInfo) ->
    ?vtrace("maybe_send_trap -> entry with"
	    "~n   NFs: ~p", [NFs]),
    case filter_notification(NFs, [], TrapRec) of
	{dont_send, [], Id} ->
	    ?vdebug("trap not sent [filter ~p]",[Id]),
	    {ok, S};
	
	{dont_send, Removed, Id} ->
	    ?vdebug("trap not sent [filter ~p]",[Id]),
	    NFs2 = del_notification_filter(Removed, NFs),
	    {ok, S#state{nfilters = NFs2}};
	
	{send, [], TrapRec2} ->
	    ?vtrace("maybe_send_trap -> send trap:"
		    "~n   ~p", [TrapRec2]),
	    do_handle_send_trap(S, TrapRec2, 
				NotifyName, ContextName, Recv, Varbinds, 
				LocalEngineID, ExtraInfo);
	
	{send, Removed, TrapRec2} ->
	    ?vtrace("maybe_send_trap -> send trap:"
		    "~n   ~p", [TrapRec2]),
	    NFs2 = del_notification_filter(Removed, NFs),
	    do_handle_send_trap(S#state{nfilters = NFs2}, TrapRec2, 
				NotifyName, ContextName, Recv, Varbinds,
				LocalEngineID, ExtraInfo)
    end.
   
do_handle_send_trap(S, TrapRec, NotifyName, ContextName, Recv, Varbinds,
		    LocalEngineID, ExtraInfo) ->
    Vbs = snmpa_trap:try_initialise_vars(get(mibserver), Varbinds),
    case S#state.type of
	subagent ->
	    forward_trap(S#state.parent, TrapRec, NotifyName, ContextName,
			 Recv, Vbs, ExtraInfo),
	    {ok, S};
	master_agent when S#state.multi_threaded =:= false ->
	    ?vtrace("do_handle_send_trap -> send trap:"
		    "~n   ~p", [TrapRec]),
	    snmpa_trap:send_trap(TrapRec, NotifyName, ContextName,
				 Recv, Vbs, LocalEngineID, ExtraInfo, 
				 get(net_if)),
	    {ok, S};
	master_agent when S#state.worker_state =:= busy ->
	    %% Main worker busy => create new worker
	    ?vtrace("do_handle_send_trap -> main worker busy: "
		    "spawn a trap sender", []),
	    spawn_trap_thread(TrapRec, NotifyName, ContextName, Recv, Vbs,
			      LocalEngineID, ExtraInfo),
	    {ok, S};
	master_agent ->
	    %% Send to main worker
	    ?vtrace("do_handle_send_trap -> send to main worker",[]),
	    S#state.worker ! ?mk_send_trap_wreq(TrapRec, NotifyName, 
						ContextName, Recv, Vbs,
						LocalEngineID, ExtraInfo),
	    {ok, S#state{worker_state = busy}}
    end.
    

filter_notification([], RemoveNFs, Notif) ->
    ?vtrace("filter_notification -> done when"
	    "~n   RemoveNFs: ~p"
	    "~n   Notif:     ~p", [RemoveNFs, Notif]),
    {send, RemoveNFs, Notif};
filter_notification([NF|NFs], RemoveNFs, Notif0) ->
    ?vtrace("filter_notification -> entry with"
	    "~n   NF:        ~p"
	    "~n   RemoveNFs: ~p"
	    "~n   Notif0:    ~p", [NF, RemoveNFs, Notif0]),
    case do_filter_notification(NF, Notif0) of
	{dont_send, Id} ->
	    {dont_send, RemoveNFs, Id};
	{send, Notif} ->
	    filter_notification(NFs, RemoveNFs, Notif);
	{error, Id} ->
	    filter_notification(NFs, [Id|RemoveNFs], Notif0)
    end.

do_filter_notification(#notification_filter{id = Id, mod = Mod, data = Data}, 
		       Notif) ->
    case (catch Mod:handle_notification(Notif, Data)) of
	dont_send ->
	    {dont_send, Id};
	send ->
	    {send, Notif};
	{send, NewNotif} ->
	    {send, NewNotif};
	Else ->
	    user_err("notification filter ~p removed: ~n~p", [Id, Else]),
	    {error, Id}
    end.


add_notification_filter(first, NewNF, NFs) ->
    {ok, [NewNF | NFs]};
add_notification_filter(last, NewNF, NFs) ->
    {ok, lists:append(NFs, [NewNF])};
add_notification_filter(Where, NewNF, NFs) ->
    case add_nf(Where, NewNF, NFs, []) of
	{ok, NFs2} ->
	    {ok, NFs2};
	Error ->
	    {Error, NFs}
    end.

add_nf({_Loc, Id}, _NewNF, [], _Acc) ->
    {error, {not_found, Id}};
add_nf({insert_before, Id}, NewNF, [NF|NFs], Acc) 
  when Id =:= NF#notification_filter.id ->
    {ok, lists:reverse(Acc) ++ [NewNF,NF|NFs]};
add_nf({insert_after, Id}, NewNF, [NF|NFs], Acc) 
  when Id =:= NF#notification_filter.id ->
    {ok, lists:reverse(Acc) ++ [NF,NewNF|NFs]};
add_nf(Where, NewNF, [NF|NFs], Acc) ->
    add_nf(Where, NewNF, NFs, [NF|Acc]).
    

del_notification_filter(IDs, NFs) ->
    Fun = fun(Id, NFilters) -> lists:keydelete(Id, 2, NFilters) end,
    lists:foldl(Fun, NFs, IDs).


handle_discovery(#state{type = master_agent} = S, From, 
		 TargetName, Notification, ContextName, Varbinds, 
		 DiscoHandler, ExtraInfo) ->
    ?vtrace("handle_discovery -> entry with"
	    "~n   TargetName:   ~p" 
	    "~n   Notification: ~p" 
	    "~n   ContextName:  ~p" 
	    "~n   Varbinds:     ~p", 
	    [TargetName, Notification, ContextName, Varbinds]),
    case snmpa_trap:construct_trap(Notification, Varbinds) of
	{ok, Record, InitVars} ->
	    ?vtrace("handle_discovery -> trap construction complete: "
		    "~n   Record:   ~p"
		    "~n   InitVars: ~p", [Record, InitVars]),
	    send_discovery(S, From, TargetName, 
			   Record, ContextName, InitVars, 
			   DiscoHandler, ExtraInfo);
	error ->
	    {error, failed_constructing_notification}
    end;
handle_discovery(_S, _From, 
		 _TargetName, _Notification, _ContextName, _Varbinds, 
		 _DiscoHandler, _ExtraInfo) ->
    {error, only_master_discovery}.
				
%% We ignore if the master agent is multi-threaded or not.
%% 
send_discovery(S, From, 
	       TargetName, Record, ContextName, InitVars, 
	       DiscoHandler, ExtraInfo) ->
    case snmpa_trap:send_discovery(TargetName, Record, ContextName,
				   InitVars, get(net_if), ExtraInfo) of
	{ok, Sender, SecLevel} ->
	    Disco = #disco{from      = From, 
			   rec       = Record,
			   sender    = Sender, 
			   target    = TargetName, 
			   sec_level = SecLevel,
			   ctx       = ContextName,
			   ivbs      = InitVars, 
			   stage     = 1,
			   handler   = DiscoHandler,
			   extra     = ExtraInfo}, 
	    {ok, S#state{disco = Disco}};
	Error ->
	    ?vlog("send_discovery -> failed sending discovery: "
		    "~n   Error: ~p", [Error]),
	    Error
    end.


handle_discovery_response(#state{disco = #disco{from = From}} = S, 
			  {error, _} = Error) ->
    ?vlog("handle_discovery_response -> entry with"
	  "~n   From:  ~p"
	  "~n   Error: ~p", [From, Error]),
    gen_server:reply(From, Error),
    S#state{disco = undefined};

handle_discovery_response(#state{disco = #disco{target = TargetName, 
						stage  = 1,
						extra  = ExtraInfo} = Disco} = S, 
			  {ok, _Pdu, ManagerEngineId}) 
  when is_record(Disco, disco) ->
    ?vlog("handle_discovery_response(1) -> entry with"
	  "~n   TargetName:      ~p"
	  "~n   ManagerEngineId: ~p", [TargetName, ManagerEngineId]),
    %% This is end of stage 1.
    %% So, first we need to update the database with the EngineId of the 
    %% manager and then deside if we should continue with stage 2. E.g.
    %% establish authenticated communication. 
    case snmp_target_mib:set_target_engine_id(TargetName, ManagerEngineId) of
	true when Disco#disco.sec_level =:= ?'SnmpSecurityLevel_noAuthNoPriv' ->
	    %% Ok, we are done
	    From    = Disco#disco.from,
	    Handler = Disco#disco.handler, 
	    Reply   = 
		case handle_discovery_stage1_finish(Handler, 
						    TargetName, 
						    ManagerEngineId, 
						    ExtraInfo) of
		    {ok, _} ->
			{ok, ManagerEngineId};
		    Error ->
			Error
		end,
	    gen_server:reply(From, Reply),
	    S#state{disco = undefined};

	true when Disco#disco.sec_level =/= ?'SnmpSecurityLevel_noAuthNoPriv' ->
	    %% Ok, time for stage 2
	    %% Send the same inform again, 
	    %% this time we have the proper EngineId

	    From    = Disco#disco.from,
	    Handler = Disco#disco.handler, 

	    case handle_discovery_stage1_finish(Handler, 
						TargetName, 
						ManagerEngineId, 
						ExtraInfo) of
		{ok, NewExtraInfo} ->
		    ?vdebug("handle_discovery_response(1) -> "
			    "we are done with stage 1 - "
			    "continue with stage 2", []),
		    #disco{rec  = Record,
			   ctx  = ContextName,
			   ivbs = InitVars} = Disco, 
		    case snmpa_trap:send_discovery(TargetName, 
						   Record, 
						   ContextName,
						   InitVars, 
						   get(net_if), 
						   ExtraInfo) of
			{ok, Sender, _SecLevel} ->
			    ?vdebug("handle_discovery_response(1) -> "
				    "stage 2 trap sent", []),
			    Disco2 = Disco#disco{sender    = Sender, 
						 engine_id = ManagerEngineId, 
						 stage     = 2,
						 extra     = NewExtraInfo}, 
			    S#state{disco = Disco2};
			Error ->
			    ?vlog("handle_discovery_response(1) -> "
				  "failed sending stage 2 trap: "
				  "~n   ~p", [Error]),
			    error_msg("failed sending second "
				      "discovery message: "
				      "~n   ~p", [Error]),
			    Reply = {error, {second_send_failed, Error}}, 
			    gen_server:reply(From, Reply),
			    S#state{disco = undefined}
		    end;
		{error, Reason} = Error ->
		    ?vlog("handle_discovery_response(1) -> "
			  "stage 1 finish failed: "
			  "~n   ~p", [Reason]),
		    gen_server:reply(From, Error),
		    S#state{disco = undefined}
	    end;
	false ->
	    ?vinfo("handle_discovery_response(1) -> "
		   "failed setting doscovered engine-id - "
		   "inform the user", []),
	    From   = Disco#disco.from,
	    Reason = {failed_setting_engine_id, TargetName, ManagerEngineId},
	    gen_server:reply(From, {error, Reason}),
	    S#state{disco = undefined}

    end;

handle_discovery_response(#state{disco = #disco{from = From, 
						engine_id = EngineID, 
						stage = 2}} = S, 
			  {ok, _Pdu}) ->
    ?vlog("handle_discovery_response(2) -> entry with"
	  "~n   From: ~p", [From]),
    gen_server:reply(From, {ok, EngineID}),
    S#state{disco = undefined};

handle_discovery_response(#state{disco = #disco{from = From}} = S, Crap) ->
    Reason = {invalid_response, Crap}, 
    gen_server:reply(From, {error, Reason}),
    S#state{disco = undefined};

handle_discovery_response(S, Crap) ->
    warning_msg("Received unexpected discovery response: ~p", [Crap]),
    S.

handle_discovery_stage1_finish(Handler, TargetName, ManagerEngineID, 
			       ExtraInfo) ->
    case (catch Handler:stage1_finish(TargetName, ManagerEngineID, 
				      ExtraInfo)) of
	ignore ->
	    ?vtrace("handle_discovery_stage1_finish -> "
		    "we are done - [ignore] inform the user", []),
	    {ok, ExtraInfo};

	{ok, UsmEntry} when is_tuple(UsmEntry) ->
	    ?vtrace("handle_discovery_stage1_finish -> "
		    "received usm entry - attempt to add it", []),
	    case add_usm_users([UsmEntry]) of
		ok ->
		    {ok,  ExtraInfo};
		Error ->
		    Error
	    end;

	{ok, UsmEntry, NewExtraInfo} when is_tuple(UsmEntry) ->
	    ?vtrace("handle_discovery_stage1_finish -> "
		    "received usm entry - attempt to add it", []),
	    case add_usm_users([UsmEntry]) of
		ok ->
		    {ok, NewExtraInfo};
		Error ->
		    Error
	    end;

	{ok, UsmEntries} when is_list(UsmEntries) ->
	    ?vtrace("handle_discovery_stage1_finish -> "
		    "received usm entries - attempt to add them", []),
	    case add_usm_users(UsmEntries) of
		ok ->
		    {ok, ExtraInfo};
		Error ->
		    Error
	    end;

	{ok, UsmEntries, NewExtraInfo} when is_list(UsmEntries) ->
	    ?vtrace("handle_discovery_stage1_finish -> "
		    "received usm entries - attempt to add them", []),
	    case add_usm_users(UsmEntries) of
		ok ->
		    {ok, NewExtraInfo};
		Error ->
		    Error
	    end;

	{'EXIT', Reason} ->
	    ?vlog("handle_discovery_stage1_finish -> stage 1 function exited: "
		  "~n   ~p", [Reason]),
	    {error, {finish_exit, Reason, ManagerEngineID}};

	{error, Reason} ->
	    ?vlog("handle_discovery_stage1_finish -> stage 1 function error: "
		  "~n   ~p", [Reason]),
	    {error, {finish_error, Reason, ManagerEngineID}};

	Unknown ->
	    ?vlog("handle_discovery_stage1_finish -> stage 1 function unknown: "
		  "~n   ~p", [Unknown]),
	    {error, {finish_failed, Unknown, ManagerEngineID}}
    end.

add_usm_users([]) ->
    ok;
add_usm_users([UsmEntry|UsmEntries]) when is_tuple(UsmEntry) ->
    ?vtrace("add_usm_users -> attempt to add entry (~w)", 
	    [element(1, UsmEntry)]),
    case snmp_user_based_sm_mib:add_user(UsmEntry) of
	{ok, _} ->
	    add_usm_users(UsmEntries);
	{error, Reason} ->
	    ?vlog("add_usm_users -> failed adding usm entry: "
		  "~n   ~p", [Reason]),
	    {error, {failed_adding_entry, Reason, UsmEntry}}
    end.

    
handle_me_of(MibServer, Oid) ->
    case snmpa_mib:lookup(MibServer, Oid) of
	{variable, ME} ->
	    {ok, ME};
	{table_column, ME, _TableEntryOid} ->
	    {ok, ME};
	{subagent, SubAgentPid, _SANextOid} ->
	    {error, {subagent, SubAgentPid}};
	{false, Reason} ->
	    {error, Reason};
	Else ->
	    {error, Else}
    end.

   
handle_mib_of(MibServer, Oid) ->
    snmpa_mib:which_mib(MibServer, Oid).


%%-----------------------------------------------------------------
%% Func: process_msg/7
%% Returns: RePdu
%%-----------------------------------------------------------------
process_msg(MibView, Vsn, Pdu, PduMS, Community, {Ip, Udp}, ContextName, 
	    GbMaxVBs) ->
    #pdu{request_id = ReqId} = Pdu,
    put(snmp_address, {tuple_to_list(Ip), Udp}),
    put(snmp_request_id, ReqId),
    put(snmp_community, Community),
    put(snmp_context, ContextName),
    ?vtrace("process ~p",[Pdu#pdu.type]),
    process_pdu(Pdu, PduMS, Vsn, MibView, GbMaxVBs).

process_pdu(#pdu{type='get-request', request_id = ReqId, varbinds=Vbs},
	    _PduMS, Vsn, MibView, _GbMaxVBs) ->
    ?vtrace("get ~p",[ReqId]),
    Res = get_err(do_get(MibView, Vbs, false)),
    ?vtrace("get result: "
	    "~n   ~p",[Res]),
    {ErrStatus, ErrIndex, ResVarbinds} =
	if
	    Vsn =:= 'version-1' -> validate_get_v1(Res);
	    true -> Res
	end,
    ?vtrace("get final result: "
	    "~n   Error status: ~p"
	    "~n   Error index:  ~p"
	    "~n   Varbinds:     ~p",
	    [ErrStatus,ErrIndex,ResVarbinds]),
    ResponseVarbinds = lists:keysort(#varbind.org_index, ResVarbinds),
    ?vtrace("response varbinds: "
	    "~n   ~p",[ResponseVarbinds]),
    make_response_pdu(ReqId, ErrStatus, ErrIndex, Vbs, ResponseVarbinds);

process_pdu(#pdu{type = 'get-next-request', request_id = ReqId, varbinds = Vbs},
	    _PduMS, Vsn, MibView, _GbMaxVBs) ->
    ?vtrace("process get-next-request -> entry with"
	    "~n   ReqId:   ~p"
	    "~n   Vbs:     ~p"
	    "~n   MibView: ~p",[ReqId, Vbs, MibView]),
    Res = get_err(do_get_next(MibView, Vbs, infinity)),
    ?vtrace("get-next result: "
	    "~n   ~p",[Res]),
    {ErrStatus, ErrIndex, ResVarbinds} = 
	if
	    Vsn =:= 'version-1' -> validate_next_v1(Res, MibView);
	    true -> Res
	end,
    ?vtrace("get-next final result -> validation result:"
	    "~n   Error status: ~p"
	    "~n   Error index:  ~p"
	    "~n   Varbinds:     ~p",[ErrStatus,ErrIndex,ResVarbinds]),
    ResponseVarbinds = lists:keysort(#varbind.org_index, ResVarbinds),
    ?vtrace("get-next final result -> response varbinds: "
	    "~n   ~p",[ResponseVarbinds]),
    make_response_pdu(ReqId, ErrStatus, ErrIndex, Vbs, ResponseVarbinds);

process_pdu(#pdu{type         = 'get-bulk-request',
		 request_id   = ReqId,
		 varbinds     = Vbs,
		 error_status = NonRepeaters, 
		 error_index  = MaxRepetitions},
	    PduMS, _Vsn, MibView, GbMaxVBs) ->
    {ErrStatus, ErrIndex, ResponseVarbinds} = 
	get_err(do_get_bulk(MibView, NonRepeaters, MaxRepetitions, PduMS, Vbs, 
			    GbMaxVBs)),
    ?vtrace("get-bulk final result: "
	    "~n   Error status:     ~p"
	    "~n   Error index:      ~p"
	    "~n   Respons varbinds: ~p",
	    [ErrStatus,ErrIndex,ResponseVarbinds]),
    make_response_pdu(ReqId, ErrStatus, ErrIndex, Vbs, ResponseVarbinds);

process_pdu(#pdu{type = 'set-request', request_id = ReqId, varbinds = Vbs},
	    _PduMS, Vsn, MibView, _GbMaxVbs)->
    Res = do_set(MibView, Vbs),
    ?vtrace("set result: "
	    "~n   ~p",[Res]),
    {ErrStatus, ErrIndex} =
	if 
	    Vsn =:= 'version-1' -> validate_err(v2_to_v1, Res);
	    true -> Res
	end,
    ?vtrace("set final result: "
	    "~n   Error status: ~p"
	    "~n   Error index:  ~p",[ErrStatus,ErrIndex]),
    make_response_pdu(ReqId, ErrStatus, ErrIndex, Vbs, Vbs).

%%-----------------------------------------------------------------
%% Transform a value == noSuchInstance | noSuchObject or a 
%% Counter64 type to a noSuchName error for the whole pdu.
%% Args: {Error, Index, Vbs}
%% Returns: {NewError, NewIndex, NewVbs}
%%-----------------------------------------------------------------
validate_get_v1({noError, _, ResponseVarbinds}) ->
    case validate_get_v1_2(ResponseVarbinds) of
	true -> {noError, 0, ResponseVarbinds};
	{Error, Index} -> {Error, Index, []} % dummy vbs
    end;
validate_get_v1({ErrStatus, ErrIndex, ResponseVarbinds}) ->
    {v2err_to_v1err(ErrStatus), ErrIndex, ResponseVarbinds}.

validate_get_v1_2([Vb | Vbs]) 
  when ((Vb#varbind.value =/= noSuchInstance) andalso 
	(Vb#varbind.value =/= noSuchObject) andalso 
	(Vb#varbind.variabletype =/= 'Counter64')) ->
    validate_get_v1_2(Vbs);
validate_get_v1_2([Vb | _Vbs]) ->
    {noSuchName, Vb#varbind.org_index};
validate_get_v1_2([]) ->
    true.

%%-----------------------------------------------------------------
%% Transform a value == endOfMibView to a noSuchName for the
%% whole pdu, and do another get-next for any Counter64 value.
%% Args: {Error, Index, Vbs}
%% Returns: {NewError, NewIndex, NewVbs}
%%-----------------------------------------------------------------
validate_next_v1({noError, _, ResponseVarbinds}, MibView) ->
    case validate_next_v1_2(ResponseVarbinds, MibView, []) of
	{true, NVbs} -> {noError, 0, NVbs};
	{Error, Index} -> {Error, Index, []} % dummy vbs
    end;
validate_next_v1({ErrStatus, ErrIndex, ResponseVarbinds}, _MibView) ->
    {v2err_to_v1err(ErrStatus), ErrIndex, ResponseVarbinds}.

validate_next_v1_2([Vb | _Vbs], _MibView, _Res)
  when Vb#varbind.value =:= endOfMibView ->
    {noSuchName, Vb#varbind.org_index};
validate_next_v1_2([Vb | Vbs], MibView, Res)
  when Vb#varbind.variabletype =:= 'Counter64' ->
    case validate_next_v1(
	   do_get_next(MibView, [mk_next_oid(Vb)], infinity), MibView) of
	{noError, 0, [NVb]} ->
	    validate_next_v1_2(Vbs, MibView, [NVb | Res]);
	{Error, Index, _OrgVb} ->
	    {Error, Index}
    end;
validate_next_v1_2([Vb | Vbs], MibView, Res) ->
    validate_next_v1_2(Vbs, MibView, [Vb | Res]);
validate_next_v1_2([], _MibView, Res) ->
    {true, Res}.

%%-----------------------------------------------------------------
%% Optimization. When we get to a Counter64 object that is a table
%% column, we'll try to find the next instance. This will be the
%% next row in the table, which is a Counter64 value as well. This
%% means that we will loop through the entire table, until we find
%% a column that isn't a Counter64 column. We can optimze this by
%% adding 1 to the column-no in the oid of this instance.
%% If the table is implemented by a subagent this does not help,
%% we'll call that subagent many times. But it shouldn't be any
%% problems.
%%-----------------------------------------------------------------
mk_next_oid(Vb) ->
    case snmpa_mib:lookup(get(mibserver), Oid = Vb#varbind.oid) of
	{table_column, _MibEntry, TableEntryOid} ->
	    [Col | _] = Oid -- TableEntryOid,
	    Vb#varbind{oid = TableEntryOid ++ [Col+1]};
	_ ->
	    Vb
    end.

%%%-----------------------------------------------------------------
%%% 3. GET REQUEST
%%% --------------
%%%   According to RFC1157, section 4.1.2 and RFC1905, section 4.2.1.
%%%   In rfc1157:4.1.2 it isn't specified if noSuchName should be
%%%   returned even if some other varbind generates a genErr.
%%%   In rfc1905:4.2.1 this is not a problem since exceptions are
%%%   used, and thus a genErr will be returned anyway.
%%%-----------------------------------------------------------------

%%-----------------------------------------------------------------
%% Func: do_get/3
%% Purpose: do_get handles "getRequests".
%% Pre: incoming varbinds have type == 'NULL', value == unSpecified
%% Returns: {noError, 0, ListOfNewVarbinds} |
%%          {ErrorStatus, ErrorIndex, []}
%%-----------------------------------------------------------------

%% If this function is called from a worker-process, we *may* 
%% need to tunnel into the master-agent and let it do the 
%% work

do_get(MibView, UnsortedVarbinds, IsNotification) ->
    do_get(MibView, UnsortedVarbinds, IsNotification, false).

do_get(MibView, UnsortedVarbinds, IsNotification, ForceMaster) ->
    ?vtrace("do_get -> entry with"
	    "~n   MibView:          ~p"
	    "~n   UnsortedVarbinds: ~p"
	    "~n   IsNotification:   ~p", 
	    [MibView, UnsortedVarbinds, IsNotification]),
    case (whereis(snmp_master_agent) =:= self()) of
	false when (ForceMaster =:= true) ->
	    %% I am a lowly worker process, handoff to the master agent
	    PduData = get_pdu_data(), 
	    call(snmp_master_agent, 
		 {do_get, MibView, UnsortedVarbinds, IsNotification, PduData});

	_ ->
	    %% This is me, the master, so go ahead
	    {OutSideView, InSideView} = 
		split_vbs_view(UnsortedVarbinds, MibView),
	    {Error, Index, NewVbs} = 
		do_get(InSideView, IsNotification),
	    {Error, Index, NewVbs ++ OutSideView}

    end.


split_vbs_view(Vbs, MibView) ->
    ?vtrace("split the varbinds view", []),
    split_vbs_view(Vbs, MibView, [], []).

split_vbs_view([Vb | Vbs], MibView, Out, In) ->
    case snmpa_acm:validate_mib_view(Vb#varbind.oid, MibView) of
	true -> split_vbs_view(Vbs, MibView, Out, [Vb | In]);
	false -> split_vbs_view(Vbs, MibView,
				[Vb#varbind{value = noSuchObject} | Out], In)
    end;
split_vbs_view([], _MibView, Out, In) ->
    {Out, In}.
	    
do_get(UnsortedVarbinds, IsNotification) ->
    {MyVarbinds, SubagentVarbinds} = sort_varbindlist(UnsortedVarbinds),
    case do_get_local(MyVarbinds, [], IsNotification) of
	{noError, 0, NewMyVarbinds} ->
	    case do_get_subagents(SubagentVarbinds, IsNotification) of
		{noError, 0, NewSubagentVarbinds} ->
		    {noError, 0, NewMyVarbinds ++ NewSubagentVarbinds};
		{ErrorStatus, ErrorIndex, _} ->
		    {ErrorStatus, ErrorIndex, []}
	    end;
	{ErrorStatus, ErrorIndex, _} -> 
	    {ErrorStatus, ErrorIndex, []}
    end.

%%-----------------------------------------------------------------
%% Func: do_get_local/3
%% Purpose: Loop the variablebindings list. We know that each varbind
%%          in that list belongs to us.
%% Returns: {noError, 0, ListOfNewVarbinds} |
%%          {ErrorStatus, ErrorIndex, []}
%%-----------------------------------------------------------------
do_get_local([Vb | Vbs], Res, IsNotification) ->
    case try_get(Vb, IsNotification) of
	NewVb when is_record(NewVb, varbind) ->
	    do_get_local(Vbs, [NewVb | Res], IsNotification);
	ListOfNewVb when is_list(ListOfNewVb) ->
	    do_get_local(Vbs, lists:append(ListOfNewVb, Res), IsNotification);
	{error, Error, OrgIndex} ->
	    {Error, OrgIndex, []}
    end;
do_get_local([], Res, _IsNotification) -> 
    {noError, 0, Res}.

%%-----------------------------------------------------------------
%% Func: do_get_subagents/2
%% Purpose: Loop the list of varbinds for different subagents.
%%          For each of them, call sub_agent_get to retreive
%%          the values for them.
%% Returns: {noError, 0, ListOfNewVarbinds} |
%%          {ErrorStatus, ErrorIndex, []}
%%-----------------------------------------------------------------
do_get_subagents(SubagentVarbinds, IsNotification) ->
    do_get_subagents(SubagentVarbinds, [], IsNotification).
do_get_subagents([{SubAgentPid, SAVbs} | Tail], Res, IsNotification) ->
    {_SAOids, Vbs} = sa_split(SAVbs),
    case catch subagent_get(SubAgentPid, Vbs, IsNotification) of
	{noError, 0, NewVbs} ->
	    do_get_subagents(Tail, lists:append(NewVbs, Res), IsNotification);
	{ErrorStatus, ErrorIndex, _} ->
	    {ErrorStatus, ErrorIndex, []};
	{'EXIT', Reason} ->
	    user_err("Lost contact with subagent (get) ~w. Using genErr", 
		     [Reason]),
	    {genErr, 0, []} 
    end;
do_get_subagents([], Res, _IsNotification) ->
    {noError, 0, Res}.


%%-----------------------------------------------------------------
%% Func: try_get/2
%% Returns: {error, ErrorStatus, OrgIndex} |
%%          #varbind |
%%          List of #varbind
%%-----------------------------------------------------------------
try_get(IVb, IsNotification) when is_record(IVb, ivarbind) ->
    ?vtrace("try_get(ivarbind) -> entry with"
	    "~n   IVb: ~p", [IVb]),
    get_var_value_from_ivb(IVb, IsNotification);
try_get({TableOid, TableVbs}, IsNotification) ->
    ?vtrace("try_get(table) -> entry with"
	    "~n   TableOid: ~p"
	    "~n   TableVbs: ~p", [TableOid, TableVbs]),
    [#ivarbind{mibentry = MibEntry}|_] = TableVbs,
    {NoAccessVbs, AccessVbs} =
	check_all_table_vbs(TableVbs, IsNotification, [], []),
    case get_tab_value_from_mib(MibEntry, TableOid, AccessVbs) of
	{error, ErrorStatus, OrgIndex} ->
	    {error, ErrorStatus, OrgIndex};
	NVbs ->
	    NVbs ++ NoAccessVbs
    end.

%%-----------------------------------------------------------------
%% Make sure all requested columns are accessible.
%%-----------------------------------------------------------------
check_all_table_vbs([IVb| IVbs], IsNotification, NoA, A) ->
    #ivarbind{mibentry = Me, varbind = Vb} = IVb,
    case Me#me.access of
	'not-accessible' -> 
	    NNoA = [Vb#varbind{value = noSuchInstance} | NoA],
	    check_all_table_vbs(IVbs, IsNotification, NNoA, A);
	'accessible-for-notify' when IsNotification =:= false -> 
	    NNoA = [Vb#varbind{value = noSuchInstance} | NoA],
	    check_all_table_vbs(IVbs, IsNotification, NNoA, A);
	'write-only' -> 
	    NNoA = [Vb#varbind{value = noSuchInstance} | NoA],
	    check_all_table_vbs(IVbs, IsNotification, NNoA, A);
	_ ->
	    check_all_table_vbs(IVbs, IsNotification, NoA, [IVb | A])
    end;
check_all_table_vbs([], _IsNotification, NoA, A) -> {NoA, A}.

%%-----------------------------------------------------------------
%% Returns: {error, ErrorStatus, OrgIndex} |
%%          #varbind
%%-----------------------------------------------------------------
get_var_value_from_ivb(IVb, IsNotification)
  when IVb#ivarbind.status =:= noError ->
    ?vtrace("get_var_value_from_ivb(noError) -> entry", []),
    #ivarbind{mibentry = Me, varbind = Vb} = IVb,
    #varbind{org_index = OrgIndex, oid = Oid} = Vb,
    case Me#me.access of
	'not-accessible' -> 
	    Vb#varbind{value = noSuchInstance};
	'accessible-for-notify' when IsNotification =:= false -> 
	    Vb#varbind{value = noSuchInstance};
	'write-only' -> 
	    Vb#varbind{value = noSuchInstance};
	_ -> 
	    case get_var_value_from_mib(Me, Oid) of
		{value, Type, Value} ->
		    Vb#varbind{variabletype = Type, value = Value};
		{error, ErrorStatus} ->
		    {error, ErrorStatus, OrgIndex}
	    end
    end;
get_var_value_from_ivb(#ivarbind{status = Status, varbind = Vb}, _) ->
    ?vtrace("get_var_value_from_ivb(~p) -> entry", [Status]),
    Vb#varbind{value = Status}.

%%-----------------------------------------------------------------
%% Func: get_var_value_from_mib/1
%% Purpose: 
%% Returns: {error, ErrorStatus} |
%%          {value, Type, Value}
%%-----------------------------------------------------------------
%% Pre: Oid is a correct instance Oid (lookup checked that).
%% Returns: A correct return value (see make_value_a_correct_value)
get_var_value_from_mib(#me{entrytype = variable,
			   asn1_type = ASN1Type,
			   mfa       = {Mod, Func, Args}},
		       _Oid) ->
    ?vtrace("get_var_value_from_mib(variable) -> entry when"
	    "~n   Mod:  ~p"
	    "~n   Func: ~p"
	    "~n   Args: ~p", [Mod, Func, Args]),
    Result = (catch dbg_apply(Mod, Func, [get | Args])),
    % mib shall return {value, <a-nice-value-within-range>} |
    % {noValue, noSuchName} (v1) | 
    % {noValue, noSuchObject | noSuchInstance} (v2, v1)
    % everything else (including 'genErr') will generate 'genErr'.
    make_value_a_correct_value(Result, ASN1Type, {Mod, Func, Args});

get_var_value_from_mib(#me{entrytype = table_column,
			   oid       = MeOid,
			   asn1_type = ASN1Type,
			   mfa       = {Mod, Func, Args}},
		       Oid) ->
    ?vtrace("get_var_value_from_mib(table_column) -> entry when"
	    "~n   MeOid: ~p"
	    "~n   Mod:   ~p"
	    "~n   Func:  ~p"
	    "~n   Args:  ~p"
	    "~n   Oid:   ~p", [MeOid, Mod, Func, Args, Oid]),
    Col = lists:last(MeOid),
    Indexes = snmp_misc:diff(Oid, MeOid),
    [Result] = (catch dbg_apply(Mod, Func, [get, Indexes, [Col] | Args])),
    make_value_a_correct_value(Result, ASN1Type, 
			       {Mod, Func, Args, Indexes, Col}).


%% For table operations we need to pass RestOid down to the table-function.
%% Its up to the table-function to check for noSuchInstance (ex: a 
%% non-existing row).
%% Returns: {error, ErrorStatus, OrgIndex} |
%%          {value, Type, Value}
get_tab_value_from_mib(#me{mfa = {Mod, Func, Args}}, TableOid, TableVbs) ->
    ?vtrace("get_tab_value_from_mib -> entry when"
	    "~n   Mod:  ~p"
	    "~n   Func: ~p"
	    "~n   Args: ~p", [Mod, Func, Args]),
    TableOpsWithShortOids = deletePrefixes(TableOid, TableVbs),
    SortedVBsRows = snmpa_svbl:sort_varbinds_rows(TableOpsWithShortOids), 
    case get_value_all_rows(SortedVBsRows, Mod, Func, Args, []) of
	{Error, Index} ->
	    #ivarbind{varbind = Vb} = lists:nth(Index, TableVbs),
	    {error, Error, Vb#varbind.org_index};
	ListOfValues -> 
	    merge_varbinds_and_value(TableVbs, ListOfValues)
    end.

%%-----------------------------------------------------------------
%% Values is a scrambled list of {CorrectValue, Index}, where Index
%% is index into the #ivarbind list. So for each Value, we must
%% find the corresponding #ivarbind, and merge them into a new
%% #varbind.
%% The Values list comes from validate_tab_res.
%%-----------------------------------------------------------------
merge_varbinds_and_value(IVbs, [{{value, Type, Value}, Index} | Values]) ->
    #ivarbind{varbind = Vb} = lists:nth(Index, IVbs),
    [Vb#varbind{variabletype = Type, value = Value} |
     merge_varbinds_and_value(IVbs, Values)];
merge_varbinds_and_value(_, []) -> [].
    
get_value_all_rows([{[], OrgCols} | Rows], Mod, Func, Args, Res) ->
    ?vtrace("get_value_all_rows -> entry when"
	    "~n   OrgCols: ~p", [OrgCols]),
    Cols   = [{{value, noValue, noSuchInstance}, Index} || 
		 {_Col, _ASN1Type, Index} <- OrgCols], 
    NewRes = lists:append(Cols, Res),
    get_value_all_rows(Rows, Mod, Func, Args, NewRes);
get_value_all_rows([{RowIndex, OrgCols} | Rows], Mod, Func, Args, Res) ->
    ?vtrace("get_value_all_rows -> entry when"
	    "~n   RowIndex: ~p"
	    "~n   OrgCols:  ~p", [RowIndex, OrgCols]),
    {DOrgCols, Dup} = remove_duplicates(OrgCols),
    Cols   = delete_index(DOrgCols),
    Result = (catch dbg_apply(Mod, Func, [get, RowIndex, Cols | Args])),
    case validate_tab_res(Result, DOrgCols, {Mod, Func, Args}) of
	Values when is_list(Values) ->
	    NVals  = restore_duplicates(Dup, Values),
	    NewRes = lists:append(NVals, Res),
	    get_value_all_rows(Rows, Mod, Func, Args, NewRes);
	{error, ErrorStatus, Index} ->
	    validate_err(row_set, {ErrorStatus, Index}, {Mod, Func, Args})
    end;
get_value_all_rows([], _Mod, _Func, _Args, Res) -> 
    ?vtrace("get_value_all_rows -> entry when done"
	    "~n   Res: ~p", [Res]),
    Res.

%%-----------------------------------------------------------------
%% Returns: list of {ShortOid, ASN1TYpe}
%%-----------------------------------------------------------------
deletePrefixes(Prefix, [#ivarbind{varbind = Varbind, mibentry = ME} | Vbs]) ->
    #varbind{oid = Oid} = Varbind,
    [{snmp_misc:diff(Oid, Prefix), ME#me.asn1_type} |
     deletePrefixes(Prefix, Vbs)];
deletePrefixes(_Prefix, []) -> [].

%%-----------------------------------------------------------------
%% Args: {RowIndex, list of {ShortOid, ASN1Type}}
%% Returns: list of Col
%%-----------------------------------------------------------------
delete_index([{Col, _Val, _OrgIndex} | T]) ->
    [Col | delete_index(T)];
delete_index([]) -> [].

%%-----------------------------------------------------------------
%% This function is called before 'get' on a table, and removes
%% any duplicate columns.  It returns {Cols, DupInfo}.  The Cols
%% are the unique columns.  The instrumentation function is
%% called to get the values.  These values, together with the
%% DupInfo, is later passed to restore_duplicates, which uses
%% the retrieved values to reconstruct the original column list,
%% but with the retrieved value for each column.
%%-----------------------------------------------------------------
remove_duplicates(Cols) ->
    remove_duplicates(Cols, [], []).


remove_duplicates([{Col, V1, OrgIdx1}, {Col, V2, OrgIdx2} | T], NCols, Dup) ->
    remove_duplicates([{Col, V1, OrgIdx1} | T], NCols, 
		      [{Col, V2, OrgIdx2} | Dup]);
remove_duplicates([Col | T], NCols, Dup) ->
    remove_duplicates(T, [Col | NCols], Dup);
remove_duplicates([], NCols, Dup) ->
    {lists:reverse(NCols), lists:reverse(Dup)}.

restore_duplicates([], Cols) ->
    [{Val, OrgIndex} || {_Col, Val, OrgIndex} <- Cols];
restore_duplicates([{Col, _Val2, OrgIndex2} | Dup],
		   [{Col, NVal, OrgIndex1} | Cols]) ->
    [{NVal, OrgIndex2} |
     restore_duplicates(Dup, [{Col, NVal, OrgIndex1} | Cols])];
restore_duplicates(Dup, [{_Col, Val, OrgIndex} | T]) ->
    [{Val, OrgIndex} | restore_duplicates(Dup, T)].

%% Maps the column number to Index.
% col_to_index(0, _) -> 0;
% col_to_index(Col, [{Col, _, Index}|_]) ->
%     Index;
% col_to_index(Col, [_|Cols]) ->
%     col_to_index(Col, Cols).

%%-----------------------------------------------------------------
%% Three cases:
%%   1) All values ok
%%   2) table_func returned {Error, ...}
%%   3) Some value in Values list is erroneous.
%% Args: Value is a list of values from table_func(get..)
%%       OrgCols is a list with {Col, ASN1Type, OrgIndex} 
%%         each element in Values and OrgCols correspond to each
%%         other.
%%-----------------------------------------------------------------
validate_tab_res(Values, OrgCols, Mfa) when is_list(Values) ->
    {_Col, _ASN1Type, OneIdx} = hd(OrgCols),
    validate_tab_res(Values, OrgCols, Mfa, [], OneIdx);
validate_tab_res({noValue, Error}, OrgCols, Mfa) ->
    Values = lists:duplicate(length(OrgCols), {noValue, Error}),
    validate_tab_res(Values, OrgCols, Mfa);
validate_tab_res({genErr, Col}, OrgCols, Mfa) ->
    case lists:keysearch(Col, 1, OrgCols) of
	{value, {_Col, _ASN1Type, Index}} ->
	    {error, genErr, Index};
	_ ->
	    user_err("Invalid column in {genErr, ~w} from ~w (get)",
		     [Col, Mfa]),
	    [{_Col, _ASN1Type, Index} | _] = OrgCols,
	    {error, genErr, Index}
    end;
validate_tab_res(genErr, [{_Col, __ASN1Type, Index} | _OrgCols], _Mfa) ->
    {error, genErr, Index};
validate_tab_res(Error, [{_Col, _ASN1Type, Index} | _OrgCols], Mfa) ->
    user_err("Invalid return value ~w from ~w (get)",[Error, Mfa]),
    {error, genErr, Index}.

validate_tab_res([Value | Values], 
		 [{Col, ASN1Type, Index} | OrgCols],
		 Mfa, Res, I) ->
    %% This one makes it possible to return a list of genErr, which
    %% is not allowed according to the manual.  But that's ok, as
    %% everything else will generate a genErr! (the only problem is
    %% that it won't generate a user_error).
    case make_value_a_correct_value(Value, ASN1Type, Mfa) of
	{error, ErrorStatus} ->
	    {error, ErrorStatus, Index};
	CorrectValue ->
	    NewRes = [{Col, CorrectValue, Index} | Res],
	    validate_tab_res(Values, OrgCols, Mfa, NewRes, I)
    end;
validate_tab_res([], [], _Mfa, Res, _I) -> 
    lists:reverse(Res);
validate_tab_res([], [{_Col, _ASN1Type, Index}|_], Mfa, _Res, _I) ->
    user_err("Too few values returned from ~w (get)", [Mfa]),
    {error, genErr, Index};
validate_tab_res(_TooMany, [], Mfa, _Res, I) ->
    user_err("Too many values returned from ~w (get)", [Mfa]),
    {error, genErr, I}.


%%%-----------------------------------------------------------------
%%% 4. GET-NEXT REQUEST
%%% --------------
%%%   According to RFC1157, section 4.1.3 and RFC1905, section 4.2.2.
%%%-----------------------------------------------------------------
%%-----------------------------------------------------------------
%% Func: do_get_next/2
%% Purpose: do_get_next handles "getNextRequests".
%% Note: Even if it is SNMPv1, a varbind's value can be
%%       endOfMibView. This is converted to noSuchName in process_pdu.
%% Returns: {noError, 0, ListOfNewVarbinds} |
%%          {ErrorStatus, ErrorIndex, []}
%% Note2: ListOfNewVarbinds is not sorted in any order!!!
%% Alg: First, the variables are sorted in OID order.
%%
%%      Second, next in the MIB is performed for each OID, and
%%      the result is collected as: if next oid is a variable,
%%      perform a get to retrieve its value; if next oid is in a
%%      table, save this value and continue until we get an oid
%%      outside this table. Then perform get_next on the table,
%%      and continue with all endOfTables and the oid outside the
%%      table; if next oid is an subagent, save this value and
%%      continue as in the table case.
%%
%%      Third, each response is checked for endOfMibView, or (for
%%      subagents) that the Oid returned has the correct prefix.
%%      (This is necessary since an SA can be registered under many
%%      separated subtrees, and if the last variable in the first
%%      subtree is requested in a next, the SA will return the first
%%      variable in the second subtree. This might be working, since
%%      there may be a variable in between these subtrees.) For each
%%      of these, a new get-next is performed, one at a time.
%%      This alg. might be optimised in several ways. The most 
%%      striking one is that the same SA might be called several
%%      times, when one time should be enough. But it isn't clear
%%      that this really matters, since many nexts across the same
%%      subagent must be considered to be very rare.
%%-----------------------------------------------------------------

%% It may be a bit agressive to check this already, 
%% but since it is a security measure, it makes sense.
do_get_next(_MibView, UnsortedVarbinds, GbMaxVBs) 
  when (is_integer(GbMaxVBs) andalso (length(UnsortedVarbinds) > GbMaxVBs)) ->
    {tooBig, 0, []}; % What is the correct index in this case?
do_get_next(MibView, UnsortedVBs, GbMaxVBs) ->
    ?vt("do_get_next -> entry when"
 	"~n   MibView:          ~p"
 	"~n   UnsortedVBs: ~p", [MibView, UnsortedVBs]),
    SortedVBs = oid_sort_vbs(UnsortedVBs),
    ?vt("do_get_next -> "
 	"~n   SortedVBs: ~p", [SortedVBs]),
    next_loop_varbinds([], SortedVBs, MibView, [], [], GbMaxVBs).

oid_sort_vbs(Vbs) ->
    lists:keysort(#varbind.oid, Vbs).

next_loop_varbinds(_, Vbs, _MibView, Res, _LAVb, GbMaxVBs) 
  when (is_integer(GbMaxVBs) andalso 
	((length(Vbs) + length(Res)) > GbMaxVBs)) ->
    {tooBig, 0, []}; % What is the correct index in this case?

%% LAVb is Last Accessible Vb
next_loop_varbinds([], [Vb | Vbs], MibView, Res, LAVb, GbMaxVBs) ->
    ?vt("next_loop_varbinds -> entry when"
 	"~n   Vb:      ~p"
 	"~n   MibView: ~p", [Vb, MibView]),
    case varbind_next(Vb, MibView) of
	endOfMibView ->
	    ?vt("next_loop_varbind -> endOfMibView", []),
	    RVb = if LAVb =:= [] -> Vb;
		     true -> LAVb
		  end,
	    NewVb = RVb#varbind{variabletype = 'NULL', value = endOfMibView},
	    next_loop_varbinds([], Vbs, MibView, [NewVb | Res], [], GbMaxVBs);

	{variable, ME, VarOid} when ((ME#me.access =/= 'not-accessible') andalso 
				     (ME#me.access =/= 'write-only') andalso 
				     (ME#me.access =/= 'accessible-for-notify')) -> 
	    ?vt("next_loop_varbind -> variable: "
		"~n   ME:     ~p"
		"~n   VarOid: ~p", [ME, VarOid]),
	    case try_get_instance(Vb, ME) of
		{value, noValue, _NoSuchSomething} ->
		    ?vt("next_loop_varbind -> noValue", []),
		    %% Try next one
		    NewVb = Vb#varbind{oid   = VarOid, 
				       value = 'NULL'},
		    next_loop_varbinds([], [NewVb | Vbs], MibView, Res, [], 
				       GbMaxVBs);
		{value, Type, Value} ->
		    ?vt("next_loop_varbind -> value"
			"~n   Type:  ~p"
			"~n   Value: ~p", [Type, Value]),
		    NewVb = Vb#varbind{oid          = VarOid, 
				       variabletype = Type,
				       value        = Value},
		    next_loop_varbinds([], Vbs, MibView, [NewVb | Res], [],
				       GbMaxVBs);
		{error, ErrorStatus} ->
		    ?vdebug("next loop varbinds:"
			    "~n   ErrorStatus: ~p",[ErrorStatus]),
		    {ErrorStatus, Vb#varbind.org_index, []}
	    end;
	{variable, _ME, VarOid} -> 
	    ?vt("next_loop_varbind -> variable: "
		"~n   VarOid: ~p", [VarOid]),
	    RVb = if LAVb =:= [] -> Vb;
		     true -> LAVb
		  end,
	    NewVb = Vb#varbind{oid = VarOid, value = 'NULL'},
	    next_loop_varbinds([], [NewVb | Vbs], MibView, Res, RVb, GbMaxVBs);
	{table, TableOid, TableRestOid, ME} ->
	    ?vt("next_loop_varbind -> table: "
		"~n   TableOid:     ~p"
		"~n   TableRestOid: ~p"
		"~n   ME:           ~p", [TableOid, TableRestOid, ME]),
	    next_loop_varbinds({table, TableOid, ME,
				[{tab_oid(TableRestOid), Vb}]},
			       Vbs, MibView, Res, [], GbMaxVBs);
	{subagent, SubAgentPid, SAOid} ->
	    ?vt("next_loop_varbind -> subagent: "
		"~n   SubAgentPid: ~p"
		"~n   SAOid:       ~p", [SubAgentPid, SAOid]),
	    NewVb = Vb#varbind{variabletype = 'NULL', value = 'NULL'},
	    next_loop_varbinds({subagent, SubAgentPid, SAOid, [NewVb]},
			       Vbs, MibView, Res, [], GbMaxVBs)
    end;
next_loop_varbinds({table, TableOid, ME, TabOids},
		   [Vb | Vbs], MibView, Res, _LAVb, GbMaxVBs) ->
    ?vt("next_loop_varbinds(table) -> entry with"
 	"~n   TableOid: ~p"
 	"~n   Vb:       ~p", [TableOid, Vb]),
    case varbind_next(Vb, MibView) of
	{table, TableOid, TableRestOid, _ME} ->
	    next_loop_varbinds({table, TableOid, ME,
				[{tab_oid(TableRestOid), Vb} | TabOids]},
			       Vbs, MibView, Res, [], GbMaxVBs);
	_ ->
	    case get_next_table(ME, TableOid, TabOids, MibView) of
		{ok, TabRes, TabEndOfTabVbs} ->
		    NewVbs = lists:append(TabEndOfTabVbs, [Vb | Vbs]),
		    NewRes = lists:append(TabRes, Res),
		    next_loop_varbinds([], NewVbs, MibView, NewRes, [], 
				       GbMaxVBs);
		{ErrorStatus, OrgIndex} ->
		    ?vdebug("next loop varbinds: next varbind"
			    "~n   ErrorStatus: ~p"
			    "~n   OrgIndex:    ~p",
			    [ErrorStatus,OrgIndex]),
		    {ErrorStatus, OrgIndex, []}
	    end
    end;
next_loop_varbinds({table, TableOid, ME, TabOids},
		   [], MibView, Res, _LAVb, GbMaxVBs) ->
    ?vt("next_loop_varbinds(table) -> entry with"
	"~n   TableOid: ~p", [TableOid]),
    case get_next_table(ME, TableOid, TabOids, MibView) of
	{ok, TabRes, TabEndOfTabVbs} ->
 	    ?vt("next_loop_varbinds(table) -> get_next_table result:"
		"~n   TabRes:         ~p"
		"~n   TabEndOfTabVbs: ~p", [TabRes, TabEndOfTabVbs]),
	    NewRes = lists:append(TabRes, Res),
	    next_loop_varbinds([], TabEndOfTabVbs, MibView, NewRes, [], 
			       GbMaxVBs);
	{ErrorStatus, OrgIndex} ->
	    ?vdebug("next loop varbinds: next table"
		    "~n   ErrorStatus: ~p"
		    "~n   OrgIndex:    ~p",
		    [ErrorStatus,OrgIndex]),
	    {ErrorStatus, OrgIndex, []}
    end;
next_loop_varbinds({subagent, SAPid, SAOid, SAVbs},
		   [Vb | Vbs], MibView, Res, _LAVb, GbMaxVBs) ->
    ?vt("next_loop_varbinds(subagent) -> entry with"
	"~n   SAPid: ~p"
	"~n   SAOid: ~p"
 	"~n   Vb:    ~p", [SAPid, SAOid, Vb]),
    case varbind_next(Vb, MibView) of
	{subagent, _SubAgentPid, SAOid} ->
	    next_loop_varbinds({subagent, SAPid, SAOid,
				[Vb | SAVbs]},
			       Vbs, MibView, Res, [], GbMaxVBs);
	_ ->
	    case get_next_sa(SAPid, SAOid, SAVbs, MibView) of
		{ok, SARes, SAEndOfMibViewVbs} ->
		    NewVbs = lists:append(SAEndOfMibViewVbs, [Vb | Vbs]),
		    NewRes = lists:append(SARes, Res),
		    next_loop_varbinds([], NewVbs, MibView, NewRes, [], 
				       GbMaxVBs);
		{noSuchName, OrgIndex} ->
		    %% v1 reply, treat this Vb as endOfMibView, and try again
		    %% for the others.
		    case lists:keysearch(OrgIndex, #varbind.org_index, SAVbs) of
			{value, EVb} ->
			    NextOid = next_oid(SAOid),
			    EndOfVb = 
				EVb#varbind{oid = NextOid,
					    value = {endOfMibView, NextOid}},
			    case lists:delete(EVb, SAVbs) of
				[] ->
				    next_loop_varbinds([], [EndOfVb, Vb | Vbs],
						       MibView, Res, [],
						       GbMaxVBs);
				TryAgainVbs ->
				    next_loop_varbinds({subagent, SAPid, SAOid,
							TryAgainVbs},
						       [EndOfVb, Vb | Vbs],
						       MibView, Res, [],
						       GbMaxVBs)
			    end;
			false ->
			    %% bad index from subagent
			    {genErr, (hd(SAVbs))#varbind.org_index, []}
		    end;
		{ErrorStatus, OrgIndex} ->
 		    ?vdebug("next loop varbinds: next subagent"
 			    "~n   Vb:          ~p"
 			    "~n   ErrorStatus: ~p"
 			    "~n   OrgIndex:    ~p",
 			    [Vb,ErrorStatus,OrgIndex]),
		    {ErrorStatus, OrgIndex, []}
	    end
    end;
next_loop_varbinds({subagent, SAPid, SAOid, SAVbs},
		   [], MibView, Res, _LAVb, GbMaxVBs) ->
     ?vt("next_loop_varbinds(subagent) -> entry with"
	 "~n   SAPid: ~p"
	 "~n   SAOid: ~p", [SAPid, SAOid]),
    case get_next_sa(SAPid, SAOid, SAVbs, MibView) of
	{ok, SARes, SAEndOfMibViewVbs} ->
	    NewRes = lists:append(SARes, Res),
	    next_loop_varbinds([], SAEndOfMibViewVbs, MibView, NewRes, [],
			       GbMaxVBs);
	{noSuchName, OrgIndex} ->
	    %% v1 reply, treat this Vb as endOfMibView, and try again for
	    %% the others.
	    case lists:keysearch(OrgIndex, #varbind.org_index, SAVbs) of
		{value, EVb} ->
		    NextOid = next_oid(SAOid),
		    EndOfVb = EVb#varbind{oid = NextOid,
					  value = {endOfMibView, NextOid}},
		    case lists:delete(EVb, SAVbs) of
			[] ->
			    next_loop_varbinds([], [EndOfVb], MibView, Res, [],
					       GbMaxVBs);
			TryAgainVbs ->
			    next_loop_varbinds({subagent, SAPid, SAOid,
						TryAgainVbs},
					       [EndOfVb], MibView, Res, [],
					       GbMaxVBs)
		    end;
		false ->
		    %% bad index from subagent
		    {genErr, (hd(SAVbs))#varbind.org_index, []}
	    end;
	{ErrorStatus, OrgIndex} ->
 	    ?vdebug("next loop varbinds: next subagent"
 		    "~n   ErrorStatus: ~p"
 		    "~n   OrgIndex:    ~p",
 		    [ErrorStatus,OrgIndex]),
 	    {ErrorStatus, OrgIndex, []}
    end;
next_loop_varbinds([], [], _MibView, Res, _LAVb, _GbMaxVBs) ->
    ?vt("next_loop_varbinds -> entry when done", []),
    {noError, 0, Res}.

try_get_instance(_Vb, #me{mfa = {M, F, A}, asn1_type = ASN1Type}) ->
    ?vtrace("try_get_instance -> entry with"
	    "~n   M: ~p"
	    "~n   F: ~p"
	    "~n   A: ~p", [M,F,A]),
    Result = (catch dbg_apply(M, F, [get | A])),
    % mib shall return {value, <a-nice-value-within-range>} |
    % {noValue, noSuchName} (v1) | 
    % {noValue, noSuchObject | noSuchInstance} (v2, v1)
    % everything else (including 'genErr') will generate 'genErr'.
    make_value_a_correct_value(Result, ASN1Type, {M, F, A}).

tab_oid([]) -> [0];
tab_oid(X) -> X.


%%-----------------------------------------------------------------
%% Perform a next, using the varbinds Oid if value is simple
%% value. If value is {endOf<something>, NextOid}, use NextOid.
%% This case happens when a table has returned endOfTable, or
%% a subagent has returned endOfMibView.
%%-----------------------------------------------------------------
varbind_next(#varbind{value = Value, oid = Oid}, MibView) ->
    ?vt("varbind_next -> entry with"
 	"~n   Value:   ~p"
 	"~n   Oid:     ~p"
 	"~n   MibView: ~p", [Value, Oid, MibView]),
    case Value of
	{endOfTable, NextOid} ->
	    snmpa_mib:next(get(mibserver), NextOid, MibView);
	{endOfMibView, NextOid} ->
	    snmpa_mib:next(get(mibserver), NextOid, MibView);
	_ ->
	    snmpa_mib:next(get(mibserver), Oid, MibView)
    end.

get_next_table(#me{mfa = {M, F, A}}, TableOid, TableOids, MibView) ->
    % We know that all TableOids have at least a column number as oid
    ?vt("get_next_table -> entry with"
	"~n   M:         ~p"
	"~n   F:         ~p"
	"~n   A:         ~p"
	"~n   TableOid:  ~p"
	"~n   TableOids: ~p"
	"~n   MibView:   ~p", [M, F, A, TableOid, TableOids, MibView]),
    Sorted = snmpa_svbl:sort_varbinds_rows(TableOids),
    case get_next_values_all_rows(Sorted, M,F,A, [], TableOid) of
	NewVbs when is_list(NewVbs) ->
 	    ?vt("get_next_table -> "
		"~n   NewVbs: ~p", [NewVbs]),
	    % We must now check each Vb for endOfTable and that it is
	    % in the MibView. If not, it becomes a endOfTable. We 
	    % collect all of these together.
	    transform_tab_next_result(NewVbs, {[], []}, MibView);
	{ErrorStatus, OrgIndex} ->
	    {ErrorStatus, OrgIndex}
    end.

get_next_values_all_rows([Row | Rows], M, F, A, Res, TabOid) ->
    {RowIndex, TableOids} = Row,
    Cols = delete_index(TableOids),
    ?vt("get_next_values_all_rows -> "
	"~n   Cols: ~p", [Cols]),
    Result = (catch dbg_apply(M, F, [get_next, RowIndex, Cols | A])),
    ?vt("get_next_values_all_rows -> "
 	"~n   Result: ~p", [Result]),
    case validate_tab_next_res(Result, TableOids, {M, F, A}, TabOid) of
	Values when is_list(Values) -> 
 	    ?vt("get_next_values_all_rows -> "
 		"~n   Values: ~p", [Values]),
	    NewRes = lists:append(Values, Res),
	    get_next_values_all_rows(Rows, M, F, A, NewRes, TabOid);
	{ErrorStatus, OrgIndex} ->
	    {ErrorStatus, OrgIndex}
    end;
get_next_values_all_rows([], _M, _F, _A, Res, _TabOid) ->
    Res.

transform_tab_next_result([Vb | Vbs], {Res, EndOfs}, MibView) ->
    case Vb#varbind.value of
	{endOfTable, _} ->
%% 	    ?vtrace("transform_tab_next_result -> endOfTable: "
%% 		"split varbinds",[]),
%% 	    R = split_varbinds(Vbs, Res, [Vb | EndOfs]),
%% 	    ?vtrace("transform_tab_next_result -> "
%% 		"~n   R: ~p", [R]),
%% 	    R;
	    split_varbinds(Vbs, Res, [Vb | EndOfs]);
	_ ->
	    case snmpa_acm:validate_mib_view(Vb#varbind.oid, MibView) of
		true ->
		    transform_tab_next_result(Vbs, {[Vb|Res], EndOfs},MibView);
		_ ->
		    Oid = Vb#varbind.oid,
		    NewEndOf = Vb#varbind{value = {endOfTable, Oid}},
		    transform_tab_next_result(Vbs, {Res, [NewEndOf | EndOfs]},
					      MibView)
	    end
    end;
transform_tab_next_result([], {Res, EndOfs}, _MibView) ->
    ?vt("transform_tab_next_result -> entry with: "
 	"~n   Res:    ~p"
 	"~n   EndIfs: ~p",[Res, EndOfs]),
    {ok, Res, EndOfs}.

%%-----------------------------------------------------------------
%% Three cases:
%%   1) All values ok
%%   2) table_func returned {Error, ...}
%%   3) Some value in Values list is erroneous.
%% Args: Value is a list of values from table_func(get_next, ...)
%%       TableOids is a list of {TabRestOid, OrgVb} 
%%         each element in Values and TableOids correspond to each
%%         other.
%% Returns: List of NewVarbinds |
%%          {ErrorStatus, OrgIndex}
%%          (In the NewVarbinds list, the value may be endOfTable)
%%-----------------------------------------------------------------
validate_tab_next_res(Values, TableOids, Mfa, TabOid) ->
     ?vt("validate_tab_next_res -> entry with: "
	 "~n   Values:     ~p"
	 "~n   TableOids:  ~p"
	 "~n   Mfa:        ~p"
	 "~n   TabOid:     ~p", [Values, TableOids, Mfa, TabOid]),
    {_Col, _ASN1Type, OneIdx} = hd(TableOids),
    validate_tab_next_res(Values, TableOids, Mfa, [], TabOid,
			  next_oid(TabOid), OneIdx).
validate_tab_next_res([{NextOid, Value} | Values],
		      [{_ColNo, OrgVb, _Index} | TableOids],
		      Mfa, Res, TabOid, TabNextOid, I) ->
    ?vt("validate_tab_next_res -> entry with: "
 	"~n   NextOid:    ~p"
 	"~n   Value:      ~p"
 	"~n   Values:     ~p"
 	"~n   TableOids:  ~p"
 	"~n   Mfa:        ~p"
 	"~n   TabOid:     ~p", 
 	[NextOid, Value, Values, TableOids, Mfa, TabOid]),
    #varbind{org_index = OrgIndex} = OrgVb,
    ?vt("validate_tab_next_res -> OrgIndex: ~p", [OrgIndex]),
    NextCompleteOid = lists:append(TabOid, NextOid),
    case snmpa_mib:lookup(get(mibserver), NextCompleteOid) of
	{table_column, #me{asn1_type = ASN1Type}, _TableEntryOid} ->
  	    ?vt("validate_tab_next_res -> ASN1Type: ~p", [ASN1Type]),
	    case make_value_a_correct_value({value, Value}, ASN1Type, Mfa) of
		{error, ErrorStatus} ->
 		    ?vt("validate_tab_next_res -> "
 			"~n   ErrorStatus: ~p", [ErrorStatus]),
		    {ErrorStatus, OrgIndex};
		{value, Type, NValue} ->
 		    ?vt("validate_tab_next_res -> "
     			"~n   Type:   ~p"
			"~n   NValue: ~p", [Type, NValue]),
		    NewVb = OrgVb#varbind{oid = NextCompleteOid,
					  variabletype = Type, value = NValue},
		    validate_tab_next_res(Values, TableOids, Mfa,
					  [NewVb | Res], TabOid, TabNextOid, I)
	    end;
	Error ->
	    user_err("Invalid oid ~w from ~w (get_next). Using genErr => ~p",
		     [NextOid, Mfa, Error]),
	    {genErr, OrgIndex}
    end;
validate_tab_next_res([endOfTable | Values],
		      [{_ColNo, OrgVb, _Index} | TableOids],
		      Mfa, Res, TabOid, TabNextOid, I) ->
     ?vt("validate_tab_next_res(endOfTable) -> entry with: "
	 "~n   Values:     ~p"
	 "~n   OrgVb:      ~p"
	 "~n   TableOids:  ~p"
	 "~n   Mfa:        ~p"
	 "~n   Res:        ~p"
	 "~n   TabOid:     ~p"
	 "~n   TabNextOid: ~p"
	 "~n   I:          ~p",
	 [Values, OrgVb, TableOids, Mfa, Res, TabOid, TabNextOid, I]),
    NewVb = OrgVb#varbind{value = {endOfTable, TabNextOid}},
    validate_tab_next_res(Values, TableOids, Mfa, [NewVb | Res],
			  TabOid, TabNextOid, I);
validate_tab_next_res([], [], _Mfa, Res, _TabOid, _TabNextOid, _I) ->
    Res;
validate_tab_next_res([], [{_Col, _OrgVb, Index}|_], Mfa, _Res, _, _, _I) ->
    user_err("Too few values returned from ~w (get_next)", [Mfa]),
    {genErr, Index};
validate_tab_next_res({genErr, ColNumber}, OrgCols,
		      Mfa, _Res, _TabOid, _TabNextOid, _I) ->
    OrgIndex = snmpa_svbl:col_to_orgindex(ColNumber, OrgCols),
    validate_err(table_next, {genErr, OrgIndex}, Mfa);
validate_tab_next_res({error, Reason}, [{_ColNo, OrgVb, _Index} | _TableOids],
		      Mfa, _Res, _TabOid, _TabNextOid, _I) ->
    #varbind{org_index = OrgIndex} = OrgVb,
    user_err("Erroneous return value ~w from ~w (get_next)",
	     [Reason, Mfa]),
    {genErr, OrgIndex};
validate_tab_next_res(Error, [{_ColNo, OrgVb, _Index} | _TableOids],
		      Mfa, _Res, _TabOid, _TabNextOid, _I) ->
    #varbind{org_index = OrgIndex} = OrgVb,
    user_err("Invalid return value ~w from ~w (get_next)",
	     [Error, Mfa]),
    {genErr, OrgIndex};
validate_tab_next_res(TooMany, [], Mfa, _Res, _, _, I) ->
    user_err("Too many values ~w returned from ~w (get_next)",
	     [TooMany, Mfa]),
    {genErr, I}.

%%-----------------------------------------------------------------
%% Func: get_next_sa/4
%% Purpose: Loop the list of varbinds for the subagent.
%%          Call subagent_get_next to retreive
%%          the next varbinds.
%% Returns: {ok, ListOfNewVbs, ListOfEndOfMibViewsVbs} |
%%          {ErrorStatus, ErrorIndex}
%%-----------------------------------------------------------------
get_next_sa(SAPid, SAOid, SAVbs, MibView) ->
    case catch subagent_get_next(SAPid, MibView, SAVbs) of
	{noError, 0, NewVbs} ->
	    NewerVbs = transform_sa_next_result(NewVbs,SAOid,next_oid(SAOid)),
	    split_varbinds(NewerVbs, [], []);
	{ErrorStatus, ErrorIndex, _} ->
	    {ErrorStatus, ErrorIndex};
	{'EXIT', Reason} ->
	    user_err("Lost contact with subagent (next) ~w. Using genErr",
		     [Reason]),
	    {genErr, 0}
    end.

%%-----------------------------------------------------------------
%% Check for wrong prefix returned or endOfMibView, and convert
%% into {endOfMibView, SANextOid}.
%%-----------------------------------------------------------------
transform_sa_next_result([Vb | Vbs], SAOid, SANextOid)
  when Vb#varbind.value =:= endOfMibView ->
    [Vb#varbind{value = {endOfMibView, SANextOid}} |
     transform_sa_next_result(Vbs, SAOid, SANextOid)];
transform_sa_next_result([Vb | Vbs], SAOid, SANextOid) ->
    case lists:prefix(SAOid, Vb#varbind.oid) of
	true ->
	    [Vb | transform_sa_next_result(Vbs, SAOid, SANextOid)];
	_ ->
	    [Vb#varbind{oid = SANextOid, value = {endOfMibView, SANextOid}} |
	     transform_sa_next_result(Vbs, SAOid, SANextOid)]
    end;
transform_sa_next_result([], _SAOid, _SANextOid) ->
    [].

split_varbinds([Vb | Vbs], Res, EndOfs) ->
    case Vb#varbind.value of
	{endOfMibView, _} -> split_varbinds(Vbs, Res, [Vb | EndOfs]);
	{endOfTable, _} -> split_varbinds(Vbs, Res, [Vb | EndOfs]);
	_ -> split_varbinds(Vbs, [Vb | Res], EndOfs)
    end;
split_varbinds([], Res, EndOfs) -> {ok, Res, EndOfs}.

next_oid(Oid) ->
    case lists:reverse(Oid) of
	[H | T] -> lists:reverse([H+1 | T]);
	[] -> []
    end.


%%%-----------------------------------------------------------------
%%% 5. GET-BULK REQUEST
%%% 
%%% In order to prevent excesses in reply sizes there are two 
%%% preventive methods in place. One is to check that the encode
%%% size does not exceed Max PDU size (this is mentioned in the
%%% standard). The other is a simple VBs limit. That is, the 
%%% resulting response cannot contain more then this number of VBs.
%%%-----------------------------------------------------------------

do_get_bulk(MibView, NonRepeaters, MaxRepetitions, PduMS, Varbinds, GbMaxVBs) ->
    ?vtrace("do_get_bulk -> entry with"
	    "~n   MibView:        ~p"
	    "~n   NonRepeaters:   ~p"
	    "~n   MaxRepetitions: ~p"
	    "~n   PduMS:          ~p"
	    "~n   Varbinds:       ~p"
	    "~n   GbMaxVBs:       ~p",
	    [MibView, NonRepeaters, MaxRepetitions, PduMS, Varbinds, GbMaxVBs]),
    {NonRepVbs, RestVbs} = split_vbs(NonRepeaters, Varbinds, []),
    ?vt("do_get_bulk -> split: "
	"~n   NonRepVbs: ~p"
	"~n   RestVbs:   ~p", [NonRepVbs, RestVbs]),
    case do_get_next(MibView, NonRepVbs, GbMaxVBs) of
	{noError, 0, UResNonRepVbs} ->
	    ?vt("do_get_bulk -> next noError: "
		"~n   UResNonRepVbs: ~p", [UResNonRepVbs]),
	    ResNonRepVbs = lists:keysort(#varbind.org_index, UResNonRepVbs),
	    %% Decode the first varbinds, produce a reversed list of
	    %% listOfBytes.
	    case (catch enc_vbs(PduMS - ?empty_pdu_size, ResNonRepVbs)) of
 		{error, Idx, Reason} ->
		    user_err("failed encoding varbind ~w:~n~p", [Idx, Reason]),
                    {genErr, Idx, []};
                {SizeLeft, Res} when is_integer(SizeLeft) and is_list(Res) ->
 		    ?vtrace("do_get_bulk -> encoded: "
			    "~n   SizeLeft: ~p"
			    "~n   Res:      ~w", [SizeLeft, Res]),
		    case (catch do_get_rep(SizeLeft, MibView, MaxRepetitions,
					   RestVbs, Res, 
					   length(UResNonRepVbs), GbMaxVBs)) of
			{error, Idx, Reason} ->
			    user_err("failed encoding varbind ~w:~n~p", 
				     [Idx, Reason]),
			    {genErr, Idx, []};
			Res when is_list(Res) ->
			    ?vtrace("do get bulk -> Res: "
				    "~n   ~w", [Res]),
			    {noError, 0, conv_res(Res)};
			{noError, 0, Data} = OK ->
			    ?vtrace("do get bulk -> OK: "
				    "~n   length(Data): ~w", [length(Data)]),
			    OK;
			Else ->
			    ?vtrace("do get bulk -> Else: "
				    "~n   ~w", [Else]),
			    Else
		    end;
		Res when is_list(Res) ->
		    {noError, 0, conv_res(Res)}
	    end;

	{ErrorStatus, Index, _} ->
	    ?vdebug("do get bulk: "
		    "~n   ErrorStatus: ~p"
		    "~n   Index:       ~p",[ErrorStatus, Index]),
	    {ErrorStatus, Index, []}
    end.

% sz(L) when list(L) -> length(L);
% sz(B) when binary(B) -> size(B);
% sz(_) -> unknown.

split_vbs(N, Varbinds, Res) when N =< 0 -> {Res, Varbinds};
split_vbs(N, [H | T], Res) -> split_vbs(N-1, T, [H | Res]);
split_vbs(_N, [], Res) -> {Res, []}.
     
enc_vbs(SizeLeft, Vbs) ->
    ?vt("enc_vbs -> entry with"
	"~n   SizeLeft: ~w", [SizeLeft]),
    Fun = fun(Vb, {Sz, Res}) when Sz > 0 ->
		  ?vt("enc_vbs -> (fun) entry with"
		      "~n   Vb:  ~p"
		      "~n   Sz:  ~p"
		      "~n   Res: ~w", [Vb, Sz, Res]),
		  case (catch snmp_pdus:enc_varbind(Vb)) of
		      {'EXIT', Reason} ->
			  ?vtrace("enc_vbs -> encode failed: "
				  "~n   Reason: ~p", [Reason]),
			  throw({error, Vb#varbind.org_index, Reason});
		      X ->
			  ?vt("enc_vbs -> X: ~w", [X]),
			  Lx = length(X),
			  ?vt("enc_vbs -> Lx: ~w", [Lx]),
			  if
			      Lx < Sz ->
				  {Sz - length(X), [X | Res]};
			      true ->
				  throw(Res)
			  end
		  end;
	     (_Vb, {_Sz, [_H | T]}) ->
		  ?vt("enc_vbs -> (fun) entry with"
		      "~n   T: ~p", [T]),
		  throw(T);
	     (_Vb, {_Sz, []}) ->
		  ?vt("enc_vbs -> (fun) entry", []),
		  throw([])
	  end,
    lists:foldl(Fun, {SizeLeft, []}, Vbs).

do_get_rep(Sz, MibView, MaxRepetitions, Varbinds, Res, GbNumVBs, GbMaxVBs) 
  when MaxRepetitions >= 0 ->
    do_get_rep(Sz, MibView, 0, MaxRepetitions, Varbinds, Res, 
	       GbNumVBs, GbMaxVBs);
do_get_rep(Sz, MibView, _MaxRepetitions, Varbinds, Res, GbNumVBs, GbMaxVBs) ->
    do_get_rep(Sz, MibView, 0, 0, Varbinds, Res, GbNumVBs, GbMaxVBs).

conv_res(ResVarbinds) ->
    conv_res(ResVarbinds, []).
conv_res([VbListOfBytes | T], Bytes) ->
    conv_res(T, VbListOfBytes ++ Bytes);
conv_res([], Bytes) ->
    Bytes.

%% The only other value, then a positive integer, is infinity.
do_get_rep(_Sz, _MibView, Count, Max, _, _Res, GbNumVBs, GbMaxVBs) 
  when (is_integer(GbMaxVBs) andalso (GbNumVBs > GbMaxVBs)) ->
    ?vinfo("Max Get-BULK VBs limit (~w) exceeded (~w) when:"
	   "~n   Count: ~p"
	   "~n   Max:   ~p", [GbMaxVBs, GbNumVBs, Count, Max]),
    {tooBig, 0, []};
do_get_rep(_Sz, _MibView, Max, Max, _, Res, _GbNumVBs, _GbMaxVBs) ->
    ?vt("do_get_rep -> done when: "
	"~n   Res: ~p", [Res]),
    {noError, 0, conv_res(Res)};
do_get_rep(Sz, MibView, Count, Max, Varbinds, Res, GbNumVBs, GbMaxVBs) -> 
    ?vt("do_get_rep -> entry when: "
	"~n   Sz:    ~p"
	"~n   Count: ~p"
	"~n   Res:   ~w", [Sz, Count, Res]),
    case try_get_bulk(Sz, MibView, Varbinds, GbMaxVBs) of
	{noError, NextVarbinds, SizeLeft, Res2} -> 
	    ?vt("do_get_rep -> noError: "
		"~n   SizeLeft: ~p"
		"~n   Res2:     ~p", [SizeLeft, Res2]),
	    do_get_rep(SizeLeft, MibView, Count+1, Max, NextVarbinds,
		       Res2 ++ Res, 
		       GbNumVBs + length(Varbinds), GbMaxVBs);
	{endOfMibView, _NextVarbinds, _SizeLeft, Res2} -> 
	    ?vt("do_get_rep -> endOfMibView: "
		"~n   Res2: ~p", [Res2]),
	    {noError, 0, conv_res(Res2 ++ Res)};
	{ErrorStatus, Index} ->
	    ?vtrace("do_get_rep -> done when error: "
		    "~n   ErrorStatus: ~p"
		    "~n   Index:       ~p", [ErrorStatus, Index]),
	    {ErrorStatus, Index, []}
    end.

org_index_sort_vbs(Vbs) ->
    lists:keysort(#varbind.org_index, Vbs).

try_get_bulk(Sz, MibView, Varbinds, GbMaxVBs) -> 
    ?vt("try_get_bulk -> entry with"
	"~n   Sz:       ~w"
	"~n   MibView:  ~w"
	"~n   Varbinds: ~w", [Sz, MibView, Varbinds]),
    case do_get_next(MibView, Varbinds, GbMaxVBs) of
	{noError, 0, UNextVarbinds} -> 
	    ?vt("try_get_bulk -> noError: "
		"~n   UNextVarbinds: ~p", [UNextVarbinds]),
	    NextVarbinds = org_index_sort_vbs(UNextVarbinds),
	    case (catch enc_vbs(Sz, NextVarbinds)) of
		{error, Idx, Reason} ->
		    user_err("failed encoding varbind ~w:~n~p", [Idx, Reason]),
		    ?vtrace("try_get_bulk -> encode error: "
			    "~n   Idx:    ~p"
			    "~n   Reason: ~p", [Idx, Reason]),
		    {genErr, Idx};
		{SizeLeft, Res} when is_integer(SizeLeft) andalso 
				     is_list(Res) ->
		    ?vt("try get bulk -> encode ok: "
			"~n   SizeLeft: ~w"
			"~n   Res:      ~w", [SizeLeft, Res]),
		    {check_end_of_mibview(NextVarbinds),
		     NextVarbinds, SizeLeft, Res};
		Res when is_list(Res) ->
		    ?vt("try get bulk -> Res: "
			"~n   ~w", [Res]),
		    {endOfMibView, [], 0, Res}
	    end;
	{ErrorStatus, Index, _} ->
	    ?vt("try_get_bulk -> error: "
		"~n   ErrorStatus: ~p"
		"~n   Index:       ~p", [ErrorStatus, Index]),
	    {ErrorStatus, Index}
    end.

%% If all variables in this pass are endOfMibView,
%% there is no reason to continue.
check_end_of_mibview([#varbind{value = endOfMibView} | T]) ->
    check_end_of_mibview(T);
check_end_of_mibview([]) -> endOfMibView;
check_end_of_mibview(_) -> noError.


%%%--------------------------------------------------
%%% 6. SET REQUEST
%%%--------------------------------------------------
%% return:  {ErrStatus, ErrIndex}
%% where ErrIndex is an index in Varbinds list (not org_index (user-functions
%% doesn't see org_index)).
do_set(MibView, UnsortedVarbinds) ->
    SetModule = get(set_module),
    ?vtrace("set module: ~p",[SetModule]),
    apply(SetModule, do_set, [MibView, UnsortedVarbinds]).

do_subagent_set(Arguments) ->
    SetModule = get(set_module),
    apply(SetModule, do_subagent_set, [Arguments]).

%%%-----------------------------------------------------------------
%%% 7. Misc functions
%%%-----------------------------------------------------------------
sort_varbindlist(Varbinds) ->
    snmpa_svbl:sort_varbindlist(get(mibserver), Varbinds).

sa_split(SubagentVarbinds) ->
    snmpa_svbl:sa_split(SubagentVarbinds).

make_response_pdu(ReqId, ErrStatus, ErrIndex, OrgVarbinds, _ResponseVarbinds)
  when ErrIndex =/= 0 ->
    #pdu{type = 'get-response', request_id = ReqId, error_status = ErrStatus,
	 error_index = ErrIndex, varbinds = OrgVarbinds};
make_response_pdu(ReqId, ErrStatus, ErrIndex, _OrgVarbinds, ResponseVarbinds) ->
    #pdu{type = 'get-response', request_id = ReqId, error_status = ErrStatus,
	 error_index = ErrIndex, varbinds = ResponseVarbinds}.

%% Valid errormsgs for different operations.
validate_err(consistency_check, {'EXIT', _Reason}, _) ->
    {genErr, 0};
validate_err(consistency_check, X, _) ->
    X;

validate_err(is_set_ok, noError, _) -> noError;
validate_err(is_set_ok, noCreation, _) -> noCreation;
validate_err(is_set_ok, inconsistentValue, _) -> inconsistentValue;
validate_err(is_set_ok, resourceUnavailable, _) -> resourceUnavailable;
validate_err(is_set_ok, inconsistentName, _) -> inconsistentName;
validate_err(is_set_ok, badValue, _) -> badValue;
validate_err(is_set_ok, wrongValue, _) -> wrongValue;
validate_err(is_set_ok, noSuchName, _) -> noSuchName;
validate_err(is_set_ok, noAccess, _) -> noAccess;
validate_err(is_set_ok, notWritable, _) -> notWritable;
validate_err(is_set_ok, genErr, _) -> genErr;
validate_err(is_set_ok, X, Mfa) -> 
    user_err("~w with is_set_ok, returned: ~w. Using genErr.",
	     [Mfa, X]),
    genErr;

validate_err(set, commitFailed, _) -> commitFailed;
validate_err(set, undoFailed, _) -> undoFailed;
validate_err(set, noError, _) -> noError;
validate_err(set, genErr, _) -> genErr;
validate_err(set, X, Mfa) -> 
    user_err("~w with set, returned: ~w. Using genErr.",
	     [Mfa, X]),
    genErr;

validate_err(undo, undoFailed, _) -> undoFailed;
validate_err(undo, noError, _) -> noError;
validate_err(undo, genErr, _) -> genErr;
validate_err(undo, X, Mfa) -> 
    user_err("~w with undo, returned: ~w. Using genErr.",
	     [Mfa, X]),
    genErr;

validate_err(table_is_set_ok, {Err, Idx}, Mfa) when is_integer(Idx) ->
    {validate_err(is_set_ok, Err, Mfa), Idx};
validate_err(table_is_set_ok, X, Mfa) ->
    user_err("~w with is_set_ok (table), returned: ~w. Using genErr.",
	     [Mfa, X]),
    {genErr, 0};

validate_err(row_is_set_ok, {Err, Idx}, _) when is_integer(Idx) ->
    {Err, Idx};
validate_err(row_is_set_ok, {_Err, {false, BadCol}}, Mfa) ->
    user_err("~w with is_set_ok (table), returned bad column: "
	     "~w. Using genErr.", [Mfa, BadCol]),
    {genErr, 0};

validate_err(table_undo, {Err, Idx}, Mfa) when is_integer(Idx) ->
    {validate_err(undo, Err, Mfa), Idx};
validate_err(table_undo, X, Mfa) ->
    user_err("~w with undo (table), returned: ~w. Using genErr.",
	     [Mfa, X]),
    {genErr, 0};

validate_err(row_undo, {Err, Idx}, _) when is_integer(Idx) ->
    {Err, Idx};
validate_err(row_undo, {_Err, {false, BadCol}}, Mfa) ->
    user_err("~w with undo (table), returned bad column: "
	     "~w. Using genErr.", [Mfa, BadCol]),
    {genErr, 0};

validate_err(table_set, {Err, Idx}, Mfa) when is_integer(Idx) ->
    {validate_err(set, Err, Mfa), Idx};
validate_err(table_set, X, Mfa) ->
    user_err("~w with set (table), returned: ~w. Using genErr.",
	     [Mfa, X]),
    {genErr, 0};

validate_err(row_set, {Err, Idx}, _) when is_integer(Idx) ->
    {Err, Idx};
validate_err(row_set, {_Err, {false, BadCol}}, Mfa) ->
    user_err("~w with set (table), returned bad column: "
	     "~w. Using genErr.", [Mfa, BadCol]),
    {genErr, 0};

validate_err(table_next, {Err, Idx}, _Mfa) when is_integer(Idx) ->
    {Err, Idx};
validate_err(table_next, {_Err, {false, BadCol}}, Mfa) ->
    user_err("~w with get_next, returned bad column: "
	     "~w. Using genErr.", [Mfa, BadCol]),
    {genErr, 0}.

validate_err(v2_to_v1, {V2Err, Index}) ->
    {v2err_to_v1err(V2Err), Index};
validate_err(v2_to_v1, _) ->
    {genErr, 0}.

get_err({ErrC, ErrI, Vbs}) ->
    {get_err_i(ErrC), ErrI, Vbs}.

get_err_i(noError) -> noError;
get_err_i(tooBig) -> tooBig;    % OTP-9700 
get_err_i(ES) -> ?vtrace("convert ErrorStatus '~p' to 'genErr'", [ES]), genErr.

v2err_to_v1err(noError) ->            noError;
v2err_to_v1err(noAccess) ->           noSuchName;
v2err_to_v1err(noCreation) ->         noSuchName;
v2err_to_v1err(notWritable) ->        noSuchName;
v2err_to_v1err(wrongLength) ->        badValue;
v2err_to_v1err(wrongEncoding) ->      badValue;
v2err_to_v1err(wrongType) ->          badValue;
v2err_to_v1err(wrongValue) ->         badValue;
v2err_to_v1err(inconsistentValue) ->  badValue;
v2err_to_v1err(inconsistentName) ->   noSuchName;
v2err_to_v1err(noSuchName) ->         noSuchName;
v2err_to_v1err(badValue) ->           badValue;
v2err_to_v1err(authorizationError) -> noSuchName;
%% genErr | resourceUnavailable | undoFailed | commitFailed -> genErr
v2err_to_v1err(_Error) ->             genErr.

%%-----------------------------------------------------------------
%% transforms a (hopefully correct) return value ((perhaps) from a 
%% mib-function) to a typed and guaranteed correct return value.
%% An incorrect return value is transformed to {error, genErr}.
%% A correct return value is on the form: 
%% {error, <error-msg>} | {value, <variable-type>, <value>}
%%-----------------------------------------------------------------
make_value_a_correct_value({value, Val}, Asn1, Mfa)
  when Asn1#asn1_type.bertype =:= 'INTEGER' ->
    check_integer(Val, Asn1, Mfa);

make_value_a_correct_value({value, Val}, Asn1, Mfa)
  when Asn1#asn1_type.bertype =:= 'Counter32' ->
    check_integer(Val, Asn1, Mfa);

make_value_a_correct_value({value, Val}, Asn1, Mfa)
  when Asn1#asn1_type.bertype =:= 'Unsigned32' ->
    check_integer(Val, Asn1, Mfa);

make_value_a_correct_value({value, Val}, Asn1, Mfa)
  when Asn1#asn1_type.bertype =:= 'TimeTicks' ->
    check_integer(Val, Asn1, Mfa);

make_value_a_correct_value({value, Val}, Asn1, Mfa)
  when Asn1#asn1_type.bertype =:= 'Counter64' ->
    check_integer(Val, Asn1, Mfa);

make_value_a_correct_value({value, Val}, Asn1, Mfa)
  when (Asn1#asn1_type.bertype =:= 'BITS') andalso is_list(Val) ->
    {value,Kibbles} = snmp_misc:assq(kibbles,Asn1#asn1_type.assocList),
    case snmp_misc:bits_to_int(Val,Kibbles) of
	error ->
	    wrongValue(Val, Mfa);
	Int ->
	    make_value_a_correct_value({value,Int},Asn1,Mfa)
    end;

make_value_a_correct_value({value, Val}, Asn1, Mfa)
  when (Asn1#asn1_type.bertype =:= 'BITS') andalso is_integer(Val) ->
    {value,Kibbles} = snmp_misc:assq(kibbles,Asn1#asn1_type.assocList),
    {_Kibble,BitNo} = lists:last(Kibbles),
    case (1 bsl (BitNo+1)) of
	X when Val < X ->
	    {value,'BITS',Val};
	_Big ->
	    wrongValue(Val, Mfa)
    end;

make_value_a_correct_value({value, String},
			   #asn1_type{bertype = 'OCTET STRING',
				      hi = Hi, lo = Lo}, Mfa) ->
    check_octet_string(String, Hi, Lo, Mfa, 'OCTET STRING');

make_value_a_correct_value({value, String},
			   #asn1_type{bertype = 'IpAddress',
				      hi = Hi, lo = Lo}, Mfa) ->
    check_octet_string(String, Hi, Lo, Mfa, 'IpAddress');

make_value_a_correct_value({value, Oid},
			   #asn1_type{bertype = 'OBJECT IDENTIFIER'},
			   _Mfa) ->
    case snmp_misc:is_oid(Oid) of
	true  -> {value, 'OBJECT IDENTIFIER', Oid};
	_Else -> {error, wrongType}
    end;

make_value_a_correct_value({value, Val}, Asn1, _Mfa)
  when Asn1#asn1_type.bertype =:= 'Opaque' ->
    if is_list(Val) -> {value, 'Opaque', Val};
       true -> {error, wrongType}
    end;

make_value_a_correct_value({noValue, noSuchObject}, _ASN1Type, _Mfa) ->
    {value, noValue, noSuchObject};
make_value_a_correct_value({noValue, noSuchInstance}, _ASN1Type, _Mfa) ->
    {value, noValue, noSuchInstance};
make_value_a_correct_value({noValue, noSuchName}, _ASN1Type, _Mfa) ->
    %% Transform this into a v2 value.  It is converted to noSuchName
    %% later if it was v1.  If it was v2, we use noSuchInstance.
    {value, noValue, noSuchInstance};
%% For backwards compatibility only - we really shouldn't allow this;
%% it makes no sense to return unSpecified for a variable! But we did
%% allow it previously. -- We transform unSpecified to noSuchInstance
%% (OTP-3303).
make_value_a_correct_value({noValue, unSpecified}, _ASN1Type, _Mfa) ->
    {value, noValue, noSuchInstance};
make_value_a_correct_value(genErr, _ASN1Type, _MFA) ->
    {error, genErr};

make_value_a_correct_value(_WrongVal, _ASN1Type, undef) ->
    {error, genErr};

make_value_a_correct_value(WrongVal, ASN1Type, Mfa) ->
    user_err("Got ~w from ~w. (~w) Using genErr",
	     [WrongVal, Mfa, ASN1Type]),
    {error, genErr}.

check_integer(Val, Asn1, Mfa) ->
    case Asn1#asn1_type.assocList of
	undefined -> check_size(Val, Asn1, Mfa);
	Alist ->
	    case snmp_misc:assq(enums, Alist) of
		{value, Enums} -> check_enums(Val, Asn1, Enums, Mfa);
		false -> check_size(Val, Asn1, Mfa)
	    end
    end.

check_octet_string(String, Hi, Lo, Mfa, Type) ->
    Len = (catch length(String)), % it might not be a list
    case snmp_misc:is_string(String) of
	true when Lo =:= undefined -> {value, Type, String};
	true when Len =< Hi, Len >= Lo ->
	    {value, Type, String};
	true ->
	    wrongLength(String, Mfa);
	_Else ->
	    wrongType(String, Mfa)
    end.

check_size(Val, #asn1_type{lo = Lo, hi = Hi, bertype = Type}, Mfa) 
  when is_integer(Val) ->
    ?vtrace("check size of integer: "
	    "~n   Value:       ~p"
	    "~n   Upper limit: ~p"
	    "~n   Lower limit: ~p"
	    "~n   BER-type:    ~p",
	    [Val,Hi,Lo,Type]),
    if
	(Lo =:= undefined) andalso (Hi =:= undefined) -> {value, Type, Val};
	(Lo =:= undefined) andalso is_integer(Hi) andalso (Val =< Hi) ->
	    {value, Type, Val};
	is_integer(Lo) andalso (Val >= Lo) andalso (Hi =:= undefined) ->
	    {value, Type, Val};
	is_integer(Lo) andalso is_integer(Hi) andalso (Val >= Lo) andalso (Val =< Hi) ->
	    {value, Type, Val};
	true ->
	    wrongValue(Val, Mfa)
    end;
check_size(Val, _, Mfa) ->
    wrongType(Val, Mfa).

check_enums(Val, Asn1, Enums, Mfa) ->
    Association = 
	if
	    is_integer(Val) -> lists:keysearch(Val, 2, Enums);
	    is_atom(Val)    -> lists:keysearch(Val, 1, Enums);
	    true            -> {error, wrongType}
    end,
    case Association of
	{value, {_AliasIntName, Val2}} -> 
	    {value, Asn1#asn1_type.bertype, Val2};
	false ->
	    wrongValue(Val, Mfa);
	{error, wrongType} ->
	    wrongType(Val, Mfa)
    end.

wrongLength(Val, Mfa) ->
    report_err(Val, Mfa, wrongLength).

wrongValue(Val, Mfa) ->
    report_err(Val, Mfa, wrongValue).

wrongType(Val, Mfa) ->
    report_err(Val, Mfa, wrongType).

report_err(_Val, undef, Err) ->
    {error, Err};
report_err(Val, Mfa, Err) ->
    user_err("Got ~p from ~w. Using ~w", [Val, Mfa, Err]),
    {error, Err}.

is_valid_pdu_type('get-request')      -> true;
is_valid_pdu_type('get-next-request') -> true;
is_valid_pdu_type('get-bulk-request') -> true;
is_valid_pdu_type('set-request')      -> true;
is_valid_pdu_type(_)                  -> false.

get_pdu_data() ->
    {get(net_if_data), 
     get(snmp_request_id),
     get(snmp_address), 
     get(snmp_community), 
     get(snmp_context)}.

put_pdu_data({Extra, ReqId, Address, Community, ContextName}) -> 
    {put(net_if_data, Extra),
     put(snmp_address, Address),
     put(snmp_request_id, ReqId),
     put(snmp_community, Community),
     put(snmp_context, ContextName)}.

tr_var(Oid, Idx) ->
    case snmp_misc:is_oid(Oid) of
	true ->
	    {#varbind{oid = Oid, value = unSpecified, org_index = Idx},
	     Idx+1};
	false -> throw({error, {bad_oid, Oid}})
    end.

tr_varbind(#varbind{value = Value}) -> Value.

mapfoldl(F, Eas, Accu0, [Hd|Tail]) ->
    {R,Accu1} = apply(F, [Hd,Accu0|Eas]),
    {Accu2,Rs} = mapfoldl(F, Eas, Accu1, Tail),
    {Accu2,[R|Rs]};
mapfoldl(_F, _Eas, Accu, []) -> {Accu,[]}.


%%-----------------------------------------------------------------
%% Runtime debugging of the agent.
%%-----------------------------------------------------------------

dbg_apply(M,F,A) ->
    case get(verbosity) of
	silence -> 
	    apply(M,F,A);
	_ ->
	    ?vlog("~n   apply: ~w,~w,~p~n", [M,F,A]),
	    Res = (catch apply(M,F,A)),
	    case Res of
		{'EXIT', Reason} ->
		    ?vinfo("Call to: "
			   "~n   Module:   ~p"
			   "~n   Function: ~p"
			   "~n   Args:     ~p"
			   "~n"
			   "~nresulted in an exit"
			   "~n"
			   "~n   ~p", [M, F, A, Reason]);
		_ ->
		    ?vlog("~n   returned: ~p", [Res])
	    end,
	    Res
    end.


short_name(none) -> ma;
short_name(_Pid) -> sa.

worker_short_name(ma) -> maw;
worker_short_name(_)  -> saw.

trap_sender_short_name(ma) -> mats;
trap_sender_short_name(_)  -> sats.

pdu_handler_short_name(ma) -> maph;
pdu_handler_short_name(_)  -> saph.


mib_server_verbosity(Pid,Verbosity) when is_pid(Pid) ->
    snmpa_mib:verbosity(Pid,Verbosity);
mib_server_verbosity(_Pid,_Verbosity) ->
    ok.

note_store_verbosity(Pid,Verbosity) when is_pid(Pid) ->
    snmp_note_store:verbosity(Pid,Verbosity);
note_store_verbosity(_Pid,_Verbosity) ->
    ok.

subagents_verbosity(V) ->
    subagents_verbosity(catch snmpa_mib:info(get(mibserver),subagents),V).

subagents_verbosity([],_V) ->
    ok;
subagents_verbosity([{Pid,_Oid}|T],V) ->
    catch verbosity(Pid,V),             %% On the agent
    catch verbosity(Pid,{subagents,V}), %% and it's subagents
    subagents_verbosity(T,V);
subagents_verbosity(_,_V) ->
    ok.


%% ---------------------------------------------------------------------

local_engine_id(#state{type = master_agent}) ->
    ?DEFAULT_LOCAL_ENGINE_ID;
local_engine_id(_) ->
    %% subagent - 
    %% we don't need this now, eventually the trap send 
    %% request will reach the master-agent and then it 
    %% will look up the proper engine id.
    ignore.


%% ---------------------------------------------------------------------

handle_get_log_type(#state{net_if_mod = Mod}) 
  when Mod =/= undefined ->
    case (catch Mod:get_log_type(get(net_if))) of
	{'EXIT', _} ->
            {error, not_supported};
        Else ->
            Else
    end;
handle_get_log_type(_) ->
    {error, not_supported}.

handle_set_log_type(#state{net_if_mod = Mod}, NewType) 
  when Mod =/= undefined ->
    case (catch Mod:set_log_type(get(net_if), NewType)) of
	{'EXIT', _} ->
            {error, not_supported};
        Else ->
            Else
    end;
handle_set_log_type(_, _) ->
    {error, not_supported}.


handle_get_request_limit(#state{net_if_mod = Mod}) 
  when Mod =/= undefined ->
    case (catch Mod:get_request_limit(get(net_if))) of
	{'EXIT', _} ->
            {error, not_supported};
        Else ->
            Else
    end;
handle_get_request_limit(_) ->
    {error, not_supported}.

handle_set_request_limit(#state{net_if_mod = Mod}, NewLimit) 
  when Mod =/= undefined ->
    case (catch Mod:set_request_limit(get(net_if), NewLimit)) of
	{'EXIT', _} ->
            {error, not_supported};
        Else ->
            Else
    end;
handle_set_request_limit(_, _) ->
    {error, not_supported}.


agent_info(#state{worker = W, set_worker = SW}) -> 
    case (catch get_agent_info(W, SW)) of
	Info when is_list(Info) ->
	    Info;
	E ->
	    [{error, E}]
    end.

get_agent_info(W, SW) ->
    MASz   = proc_mem(self()),
    WSz    = proc_mem(W),
    SWSz   = proc_mem(SW),
    ATSz   = tab_mem(snmp_agent_table),
    CCSz   = tab_mem(snmp_community_cache),
    VacmSz = tab_mem(snmpa_vacm),
    [{process_memory, [{master_agent, MASz}, 
		       {worker,       WSz}, 
		       {set_worker,   SWSz}]}, 
     {db_memory, [{agent,           ATSz}, 
		  {community_cache, CCSz}, 
		  {vacm,            VacmSz}]}].

proc_mem(P) when is_pid(P) ->
    case (catch erlang:process_info(P, memory)) of
	{memory, Sz} when is_integer(Sz) ->
	    Sz;
	_ ->
	    undefined
    end;
proc_mem(_) ->
    undefined.

tab_mem(T) ->
    case (catch ets:info(T, memory)) of
	Sz when is_integer(Sz) ->
	    Sz;
	_ ->
	    undefined
    end.

net_if_info(#state{net_if_mod = Mod}) when Mod =/= undefined ->
    case (catch Mod:info(get(net_if))) of
	Info when is_list(Info) ->
	    Info;
	E ->
	    [{error, E}]
    end;
net_if_info(_) ->
    %% This could be a result of a code upgrade
    %% Make best effert
    [{process_memory, proc_mem(get(net_if))}].

note_store_info(#state{note_store = NS}) ->
    case (catch snmp_note_store:info(NS)) of
	Info when is_list(Info) ->
	    Info;
	E ->
	    [{error, E}]
    end.

symbolic_store_info() ->
    case (catch snmpa_symbolic_store:info()) of
	Info when is_list(Info) ->
	    Info;
	E ->
	    [{error, E}]
    end.

local_db_info() ->
    case (catch snmpa_local_db:info()) of
	Info when is_list(Info) ->
	    Info;
	E ->
	    [{error, E}]
    end.

mib_server_info() ->
    case (catch snmpa_mib:info(get(mibserver))) of
	Info when is_list(Info) ->
	    Info;
	E ->
	    [{error, E}]
    end.
	
get_stats_counters() ->
    Counters = snmpa_mpd:counters(),
    get_stats_counters(Counters, []).

get_stats_counters([], Acc) ->
    lists:reverse(Acc);
get_stats_counters([Counter|Counters], Acc) ->
    case ets:lookup(snmp_agent_table, Counter) of
	[CounterVal] ->
	    get_stats_counters(Counters, [CounterVal|Acc]);
	_ ->
	    get_stats_counters(Counters, Acc)
    end.


%% ---------------------------------------------------------------------

%% info_msg(F, A) ->
%%     ?snmpa_info(F, A).

warning_msg(F, A) ->
    ?snmpa_warning(F, A).

error_msg(F, A) ->
    ?snmpa_error(F, A).

%% --- 

config_err(F, A) ->
    snmpa_error:config_err(F, A).

user_err(F, A) ->
    snmpa_error:user_err(F, A).


%% ---------------------------------------------------------------------

maybe_call(Server, Req) ->
    case (wis(Server) =:= self()) of
	false ->
	    call(Server, Req);
	true ->
	    Server ! Req
    end.

call(Server, Req) ->
    gen_server:call(Server, Req, infinity).

cast(Server, Msg) ->
    gen_server:cast(Server, Msg).


%% ---------------------------------------------------------------------

get_verbosity(Opts) ->
    get_option(verbosity, Opts, ?default_verbosity).

get_mibs(Opts) ->
    get_option(mibs, Opts, []).

get_mib_storage(Opts) ->
    get_option(mib_storage, Opts).

get_set_mechanism(Opts) ->
    get_option(set_mechanism, Opts, snmpa_set).

get_authentication_service(Opts) ->
    get_option(authentication_service, Opts, snmpa_acm).

get_multi_threaded(Opts) ->
    get_option(multi_threaded, Opts, false).

get_versions(Opts) ->
    get_option(versions, Opts, [v1,v2,v3]).

get_gb_max_vbs(Opts) ->
    get_option(gb_max_vbs, Opts, infinity).

get_note_store_opt(Opts) ->
    get_option(note_store, Opts, []).

get_net_if_opt(Opts) ->
    get_option(net_if, Opts, []).

get_net_if_verbosity(Opts) ->
    get_option(verbosity, Opts, silence).

get_net_if_module(Opts) ->
    get_option(module, Opts, snmpa_net_if).

get_net_if_options(Opts) ->
    get_option(options, Opts, []).


net_if_verbosity(Pid,Verbosity) when is_pid(Pid) ->
    Pid ! {verbosity,Verbosity};
net_if_verbosity(_Pid,_Verbosity) ->
    ok.


get_option(Key, Opts) ->
    snmp_misc:get_option(Key, Opts).

get_option(Key, Opts, Default) ->
    snmp_misc:get_option(Key, Opts, Default).


%% ---------------------------------------------------------------------


%% i(F) ->
%%     i(F, []).

%% i(F, A) ->
%%     io:format("~p: " ++ F ++ "~n", [?MODULE|A]).