[snmp|agent] Add the default get-mechanism module snmpa_get

Added the snmpa_get module as the default get-mechanism
for the agent.
This has been done by simply moving the do_get, do_get_next
and do_get_bulk functions from the snmpa_agent module.
Some functions where also moved into the lib module (with
the idea of beeing more generally useful).

OTP-15691

1 files changed, 253 insertions, 0 deletions

diff --git a/lib/snmp/src/agent/snmpa_get_lib.erl b/lib/snmp/src/agent/snmpa_get_lib.erl
new file mode 100644
index 0000000000..7929b10cf3
--- /dev/null
+++ b/lib/snmp/src/agent/snmpa_get_lib.erl
@@ -0,0 +1,253 @@
+%%
+%% %CopyrightBegin%
+%%
+%% Copyright Ericsson AB 2019-2019. All Rights Reserved.
+%%
+%% Licensed under the Apache License, Version 2.0 (the "License");
+%% you may not use this file except in compliance with the License.
+%% You may obtain a copy of the License at
+%%
+%%     http://www.apache.org/licenses/LICENSE-2.0
+%%
+%% Unless required by applicable law or agreed to in writing, software
+%% distributed under the License is distributed on an "AS IS" BASIS,
+%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+%% See the License for the specific language governing permissions and
+%% limitations under the License.
+%%
+%% %CopyrightEnd%
+%%
+
+%%
+%% Note that most of these functions *assume* that they are executed
+%% by the agent. If they are not they may note work as they require
+%% some properties to be set in the process dictionary!
+%%
+
+-module(snmpa_get_lib).
+
+-export([
+         split_vbs/1, split_vbs/3,
+         split_vbs_view/2,
+         split_vbs_gb/2,
+
+         agent_sort_vbs/1,
+         oid_sort_vbs/1, org_index_sort_vbs/1,
+
+         sa_split/1,
+
+         delete_prefixes/2,
+
+         dbg_apply/3,
+
+         user_err/2
+        ]).
+
+-include("snmpa_internal.hrl").
+-include("snmp_types.hrl").
+-include("snmp_debug.hrl").
+-include("snmp_verbosity.hrl").
+
+
+
+
+%%-----------------------------------------------------------------
+%% split_vbs/1,3
+%%
+%% Splits the list of varbinds (basically) into two lists. One
+%% of 'end of'-varbinds (mib view and tables) and then the rest
+%% of the varbinds.
+%%-----------------------------------------------------------------
+
+-spec split_vbs(VBs :: [snmp:varbind()]) ->
+                       {ResVBs   :: [snmp:varbind()], 
+                        EndOfVBs :: [snmp:varbind()]}.
+
+split_vbs(VBs) ->
+    split_vbs(VBs, [], []).
+
+-spec split_vbs(VBs    :: [snmp:varbind()],
+                Res    :: [snmp:varbind()],
+                EndOfs :: [snmp:varbind()]) ->
+                       {ResVBs   :: [snmp:varbind()],
+                        EndOfVBs :: [snmp:varbind()]}.
+
+split_vbs([], ResVBs, EndOfVBs) ->
+    {ResVBs, EndOfVBs};
+split_vbs([VB | VBs], Res, EndOfs) ->
+    case VB#varbind.value of
+        {endOfMibView, _} -> split_vbs(VBs, Res, [VB | EndOfs]);
+        {endOfTable, _}   -> split_vbs(VBs, Res, [VB | EndOfs]);
+        _                 -> split_vbs(VBs, [VB | Res], EndOfs)
+    end.
+
+
+
+%%-----------------------------------------------------------------
+%% split_vbs_view/2
+%%
+%% Splits a list of varbinds into two lists based on the provided
+%% MibView. One list of varbinds inside the MibView and one of
+%% varbinds outside the MibView.
+%%-----------------------------------------------------------------
+
+-spec split_vbs_view(VBs     :: [snmp:varbind()],
+                     MibView :: snmp_view_based_acm_mib:mibview()) ->
+                            {OutSideView :: [snmp:varbind()],
+                             InSideView  :: [snmp:varbind()]}.
+
+split_vbs_view(VBs, MibView) ->
+    ?vtrace("split the varbinds view", []),
+    split_vbs_view(VBs, MibView, [], []).
+
+split_vbs_view([], _MibView, Out, In) ->
+    {Out, In};
+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 ->
+            VB2 = VB#varbind{value = noSuchObject},
+            split_vbs_view(VBs, MibView, [VB2 | Out], In)
+    end.
+
+
+
+%%-----------------------------------------------------------------
+%% split_vbs_gb/2
+%%
+%% Performs a get-bulk split of the varbinds
+%%-----------------------------------------------------------------
+
+-spec split_vbs_gb(NonRepeaters :: integer(),
+                   VBs          :: [snmp:varbind()]) ->
+                          {NonRepVBs :: [snmp:varbind()], 
+                           RestVBs   :: [snmp:varbind()]}.
+
+split_vbs_gb(N, VBs) ->
+    split_vbs_gb(N, VBs, []).
+
+split_vbs_gb(N, Varbinds, Res) when N =< 0 ->
+    {Res, Varbinds};
+split_vbs_gb(N, [H | T], Res) ->
+    split_vbs_gb(N-1, T, [H | Res]);
+split_vbs_gb(_N, [], Res) ->
+    {Res, []}.
+
+
+
+%%-----------------------------------------------------------------
+%% agent_sort_vbs/1
+%%
+%% Sorts the varbinds into two categories. The first is varbinds
+%% belonging to "our" agent and the other is varbinds for 
+%% subagents.
+%%-----------------------------------------------------------------
+
+-spec agent_sort_vbs(VBs :: [snmp:varbind()]) ->
+                      {AgentVBs    :: [snmp:varbind()],
+                       SubAgentVBs :: [snmp:varbind()]}.
+
+agent_sort_vbs(VBs) ->
+    snmpa_svbl:sort_varbindlist(get(mibserver), VBs).
+
+
+%%-----------------------------------------------------------------
+%% oid_sort_vbs/1
+%%
+%% Sorts the varbinds based on their oid.
+%%-----------------------------------------------------------------
+
+-spec oid_sort_vbs(VBs :: [snmp:varbind()]) -> SortedVBs :: [snmp:varbind()].
+
+oid_sort_vbs(VBs) ->
+    lists:keysort(#varbind.oid, VBs).
+
+
+%%-----------------------------------------------------------------
+%% org_index_sort_vbs/1
+%%
+%% Sorts the varbinds based on their org_index.
+%%-----------------------------------------------------------------
+
+-spec org_index_sort_vbs(VBs :: [snmp:varbind()]) -> SortedVBs :: [snmp:varbind()].
+
+org_index_sort_vbs(Vbs) ->
+    lists:keysort(#varbind.org_index, Vbs).
+
+
+
+%%-----------------------------------------------------------------
+%% sa_split/1
+%%
+%% Splits a list of {oid(), varbind()} into two lists of oid() 
+%% and varbind. The resulting lists are reversed!
+%%-----------------------------------------------------------------
+
+-spec sa_split(SAVBs :: [{SAOid :: snmp:oid(), snmp:varbind()}]) ->
+                      {Oids :: [snmp:oid()], VBs :: [snmp:varbind()]}.
+
+sa_split(SAVBs) ->
+    snmpa_svbl:sa_split(SAVBs).
+
+
+
+%%-----------------------------------------------------------------
+%% delete_prefixes/2
+%%
+%% Takes an Oid prefix and a list of ivarbinds and produces a list
+%% of {ShortOid, ASN1Type}. The ShortOid is basically the oid with 
+%% the OidPrefix removed.
+%%-----------------------------------------------------------------
+
+-spec delete_prefixes(OidPrefix :: snmp:oid(),
+                      VBs       :: [snmp:ivarbind()]) ->
+                             [{ShortOid :: snmp:oid(),
+                               ASN1Type :: snmp:asn1_type()}].
+
+delete_prefixes(OidPrefix, IVBs) ->
+    [{snmp_misc:diff(Oid, OidPrefix), ME#me.asn1_type} ||
+        #ivarbind{varbind = #varbind{oid = Oid}, mibentry = ME} <- IVBs].
+
+
+
+%%-----------------------------------------------------------------
+%% dbg_apply/3
+%%
+%% Call instrumentation functions, but allow for debug printing
+%% of useful debug info.
+%%-----------------------------------------------------------------
+
+-spec dbg_apply(M :: atom(), F :: atom(), A :: list()) ->
+                       any().
+
+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.
+
+
+%% ---------------------------------------------------------------------
+
+user_err(F, A) ->
+    snmpa_error:user_err(F, A).
+
+