Merge branch 'anders/diameter/sequence_masks/OTP-10445' into maint

* anders/diameter/sequence_masks/OTP-10445:
  Redo watchdog test suite
  Update/clarify some comments
  Add reopen message from watchdog
  Add options service_info
  Add diameter_reg:wait/1
  Clarify diameter_transport doc
  Remove pre-OTP configure support
  Remove obsolete make target
  Use sequence masks in test suites
  Implement sequence masks
  Document sequence masks

9 files changed, 609 insertions, 363 deletions

diff --git a/lib/diameter/src/Makefile b/lib/diameter/src/Makefile
index 99c343275b..060659bce9 100644
--- a/lib/diameter/src/Makefile
+++ b/lib/diameter/src/Makefile
@@ -16,13 +16,8 @@
 # 
 # %CopyrightEnd%
 
-ifeq ($(ERL_TOP),)
-include $(DIAMETER_TOP)/make/target.mk
-include $(DIAMETER_TOP)/make/$(TARGET)/rules.mk
-else
 include $(ERL_TOP)/make/target.mk
 include $(ERL_TOP)/make/$(TARGET)/otp.mk
-endif
 
 # ----------------------------------------------------
 # Application version
@@ -210,11 +205,7 @@ dialyze: opt $(PLT)
 # Release targets
 # ----------------------------------------------------
 
-ifeq ($(ERL_TOP),)
-include $(DIAMETER_TOP)/make/release_targets.mk
-else
 include $(ERL_TOP)/make/otp_release_targets.mk
-endif
 
 # Can't $(INSTALL_DIR) more than one directory at a time on Solaris.
 
diff --git a/lib/diameter/src/base/diameter.erl b/lib/diameter/src/base/diameter.erl
index 4f90b741ae..d60510db7d 100644
--- a/lib/diameter/src/base/diameter.erl
+++ b/lib/diameter/src/base/diameter.erl
@@ -44,6 +44,7 @@
          stop/0]).
 
 -export_type([evaluable/0,
+              sequence/0,
               app_alias/0,
               service_name/0,
               capability/0,
@@ -280,11 +281,15 @@ call(SvcName, App, Message) ->
     | fun()
     | maybe_improper_list(evaluable(), list()).
 
+-type sequence()
+   :: {'Unsigned32'(), 0..32}.
+
 %% Options passed to start_service/2
 
 -type service_opt()
    :: capability()
-    | {application, [application_opt()]}.
+    | {application, [application_opt()]}
+    | {sequence, sequence() | evaluable()}.
 
 -type application_opt()
    :: {alias, app_alias()}
diff --git a/lib/diameter/src/base/diameter_config.erl b/lib/diameter/src/base/diameter_config.erl
index d1916c26e6..fc37ca8541 100644
--- a/lib/diameter/src/base/diameter_config.erl
+++ b/lib/diameter/src/base/diameter_config.erl
@@ -97,6 +97,9 @@
 -record(monitor, {mref = make_ref() :: reference(),
                   service}). %% name
 
+%% The default sequence mask.
+-define(NOMASK, {0,32}).
+
 %% Time to lay low before restarting a dead service.
 -define(RESTART_SLEEP, 2000).
 
@@ -549,9 +552,10 @@ make_config(SvcName, Opts) ->
 
     ok = encode_CER(COpts),
 
-    Os = split(Opts, [{[fun erlang:is_boolean/1], false, share_peers},
-                      {[fun erlang:is_boolean/1], false, use_shared_peers},
-                      {[fun erlang:is_pid/1, false], false, monitor}]),
+    Os = split(Opts, fun opt/2, [{false, share_peers},
+                                 {false, use_shared_peers},
+                                 {false, monitor},
+                                 {?NOMASK, sequence}]),
     %% share_peers and use_shared_peers are currently undocumented.
 
     #service{name = SvcName,
@@ -559,6 +563,43 @@ make_config(SvcName, Opts) ->
                                      capabilities = Caps},
              options = Os}.
 
+split(Opts, F, Defs) ->
+    [{K, F(K, get_opt(K, Opts, D))} || {D,K} <- Defs].
+
+opt(K, false = B)
+  when K /= sequence ->
+    B;
+
+opt(K, true = B)
+  when K == share_peer;
+       K == use_shared_peers ->
+    B;
+
+opt(monitor, P)
+  when is_pid(P) ->
+    P;
+
+opt(sequence, {_,_} = T) ->
+    sequence(T);
+
+opt(sequence, F) ->
+    try diameter_lib:eval(F) of
+        T -> sequence(T)
+    catch
+        E:R ->
+            ?THROW({value, {sequence, E, R, ?STACK}})
+    end;
+            
+opt(K, _) ->
+    ?THROW({value, K}).
+
+sequence({H,N} = T)
+  when 0 =< N, N =< 32, 0 =< H, 0 == H bsr N ->
+    T;
+    
+sequence(_) ->
+    ?THROW({value, sequence}).
+
 make_caps(Caps, Opts) ->
     case diameter_capx:make_caps(Caps, Opts) of
         {ok, T} ->
@@ -663,21 +704,6 @@ get_opt(Key, List, Def) ->
         _   -> ?THROW({arity, Key})
     end.
 
-split(Opts, Defs) ->
-    [{K, value(D, Opts)} || {_,_,K} = D <- Defs].
-
-value({Preds, Def, Key}, Opts) ->
-    V = get_opt(Key, Opts, Def),
-    lists:any(fun(P) -> pred(P,V) end, Preds)
-        orelse ?THROW({value, Key}),
-    V.
-
-pred(F, V)
-  when is_function(F) ->
-    F(V);
-pred(T, V) ->
-    T == V.
-
 cb(M,F) ->
     try M:F() of
         V -> V
diff --git a/lib/diameter/src/base/diameter_peer.erl b/lib/diameter/src/base/diameter_peer.erl
index 46b2ba9465..1b2f32ddff 100644
--- a/lib/diameter/src/base/diameter_peer.erl
+++ b/lib/diameter/src/base/diameter_peer.erl
@@ -76,7 +76,7 @@ notify(SvcName, T) ->
 %%% # start/3
 %%% ---------------------------------------------------------------------------
 
-%% From old code: make is restart.
+%% From old code: make it restart.
 start(_T, _Opts, #diameter_service{}) ->
     {error, restart}.
 
diff --git a/lib/diameter/src/base/diameter_peer_fsm.erl b/lib/diameter/src/base/diameter_peer_fsm.erl
index 302540e76b..8ce6ea847a 100644
--- a/lib/diameter/src/base/diameter_peer_fsm.erl
+++ b/lib/diameter/src/base/diameter_peer_fsm.erl
@@ -55,10 +55,14 @@
 -define(TLS, 1).
 
 %% Keys in process dictionary.
--define(CB_KEY, cb).       %% capabilities callback
--define(DWA_KEY, dwa).     %% outgoing DWA
--define(Q_KEY, q).         %% transport start queue
--define(START_KEY, start). %% start of connected transport
+-define(CB_KEY, cb).         %% capabilities callback
+-define(DWA_KEY, dwa).       %% outgoing DWA
+-define(Q_KEY, q).           %% transport start queue
+-define(START_KEY, start).   %% start of connected transport
+-define(SEQUENCE_KEY, mask). %% mask for sequence numbers
+
+%% The default sequence mask.
+-define(NOMASK, {0,32}).
 
 %% A 2xxx series Result-Code. Not necessarily 2001.
 -define(IS_SUCCESS(N), 2 == (N) div 1000).
@@ -121,7 +125,8 @@
 %%% Output: Pid
 %%% ---------------------------------------------------------------------------
 
--spec start(T, [Opt], #diameter_service{})
+-spec start(T, [Opt], #diameter_service{}  %% from old code
+                    | {diameter:sequence(), #diameter_service{}})
    -> pid()
  when T   :: {connect|accept, diameter:transport_ref()},
       Opt :: diameter:transport_opt().
@@ -131,10 +136,8 @@
 %% specified on the transport in question. Check here that the list is
 %% still non-empty.
 
-start({_,_} = Type, Opts, #diameter_service{applications = Apps} = Svc) ->
-    [] /= Apps orelse ?ERROR({no_apps, Type, Opts}),
-    T = {self(), Type, Opts, Svc},
-    {ok, Pid} = diameter_peer_fsm_sup:start_child(T),
+start({_,_} = Type, Opts, MS) ->
+    {ok, Pid} = diameter_peer_fsm_sup:start_child({self(), Type, Opts, MS}),
     Pid.
 
 start_link(T) ->
@@ -153,12 +156,19 @@ init(T) ->
     proc_lib:init_ack({ok, self()}),
     gen_server:enter_loop(?MODULE, [], i(T)).
 
-i({WPid, T, Opts, #diameter_service{capabilities = Caps} = Svc}) ->
+i({WPid, Type, Opts, #diameter_service{} = Svc}) ->  %% from old code
+    i({WPid, Type, Opts, {?NOMASK, Svc}});
+
+i({WPid, T, Opts, {Mask, #diameter_service{applications = Apps,
+                                           capabilities = Caps}
+                         = Svc}}) ->
+    [] /= Apps orelse ?ERROR({no_apps, T, Opts}),
     putr(?DWA_KEY, dwa(Caps)),
     {M, Ref} = T,
     diameter_stats:reg(Ref),
     {[Ts], Rest} = proplists:split(Opts, [capabilities_cb]),
     putr(?CB_KEY, {Ref, [F || {_,F} <- Ts]}),
+    putr(?SEQUENCE_KEY, Mask),
     erlang:monitor(process, WPid),
     {TPid, Addrs} = start_transport(T, Rest, Svc),
     #state{parent = WPid,
@@ -464,9 +474,24 @@ build_CER(#state{service = #diameter_service{capabilities = Caps}}) ->
 %% encode/1
 
 encode(Rec) ->
-    #diameter_packet{bin = Bin} = diameter_codec:encode(?BASE, Rec),
+    Seq = diameter_session:sequence(sequence()),
+    Hdr = #diameter_header{version = ?DIAMETER_VERSION,
+                           end_to_end_id = Seq,
+                           hop_by_hop_id = Seq},
+    Pkt = #diameter_packet{header = Hdr,
+                           msg = Rec},
+    #diameter_packet{bin = Bin} = diameter_codec:encode(?BASE, Pkt),
     Bin.
 
+sequence() ->
+    case getr(?SEQUENCE_KEY) of
+        {_,_} = Mask ->
+            Mask;
+        undefined ->  %% started in old code
+            putr(?SEQUENCE_KEY, ?NOMASK),
+            ?NOMASK
+    end.
+
 %% recv/2
 
 %% RFC 3588 has result code 5015 for an invalid length but if a
diff --git a/lib/diameter/src/base/diameter_reg.erl b/lib/diameter/src/base/diameter_reg.erl
index 882b9da238..619b12ecad 100644
--- a/lib/diameter/src/base/diameter_reg.erl
+++ b/lib/diameter/src/base/diameter_reg.erl
@@ -1,7 +1,7 @@
 %%
 %% %CopyrightBegin%
 %%
-%% Copyright Ericsson AB 2010-2011. All Rights Reserved.
+%% Copyright Ericsson AB 2010-2012. 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
@@ -30,7 +30,8 @@
          add_new/1,
          del/1,
          repl/2,
-         match/1]).
+         match/1,
+         wait/1]).
 
 -export([start_link/0]).
 
@@ -65,27 +66,22 @@
 %% Table entry containing the Term -> Pid mapping.
 -define(MAPPING(Term, Pid), {Term, Pid}).
 
--record(state, {id = now()}).
-
-%%% ----------------------------------------------------------
-%%% # add(T)
-%%%
-%%% Input:  Term = term()
-%%%
-%%% Output: true
-%%%
-%%% Description: Associate the specified term with self(). The list of pids
-%%%              having this or other assocations can be retrieved using
-%%%              match/1.
-%%%
-%%%              An association is removed when the calling process dies
-%%%              or as a result of calling del/1. Adding the same term
-%%%              more than once is equivalent to adding it exactly once.
-%%%
-%%%              Note that since match/1 takes a pattern as argument,
-%%%              specifying a term that contains match variables is
-%%%              probably not a good idea
-%%% ----------------------------------------------------------
+-record(state, {id = now(),
+                q = []}). %% [{From, Pat}]
+
+%% ===========================================================================
+%% # add(T)
+%%
+%% Associate the specified term with self(). The list of pids having
+%% this or other assocations can be retrieved using match/1.
+%%
+%% An association is removed when the calling process dies or as a
+%% result of calling del/1. Adding the same term more than once is
+%% equivalent to adding it exactly once.
+%%
+%% Note that since match/1 takes a pattern as argument, specifying a
+%% term that contains match variables is probably not a good idea
+%% ===========================================================================
 
 -spec add(any())
    -> true.
@@ -93,17 +89,12 @@
 add(T) ->
     call({add, fun ets:insert/2, T, self()}).
 
-%%% ----------------------------------------------------------
-%%% # add_new(T)
-%%%
-%%% Input:  T = term()
-%%%
-%%% Output: true | false
-%%%
-%%% Description: Like add/1 but only one process is allowed to have the
-%%%              the association, false being returned if an association
-%%%              already exists.
-%%% ----------------------------------------------------------
+%% ===========================================================================
+%% # add_new(T)
+%%
+%% Like add/1 but only one process is allowed to have the the
+%% association, false being returned if an association already exists.
+%% ===========================================================================
 
 -spec add_new(any())
    -> boolean().
@@ -111,16 +102,12 @@ add(T) ->
 add_new(T) ->
     call({add, fun insert_new/2, T, self()}).
 
-%%% ----------------------------------------------------------
-%%% # repl(T, NewT)
-%%%
-%%% Input:  T, NewT = term()
-%%%
-%%% Output: true | false
-%%%
-%%% Description: Like add/1 but only replace an existing association on T,
-%%%              false being returned if it doesn't exist.
-%%% ----------------------------------------------------------
+%% ===========================================================================
+%% # repl(T, NewT)
+%%
+%% Like add/1 but only replace an existing association on T, false
+%% being returned if it doesn't exist.
+%% ===========================================================================
 
 -spec repl(any(), any())
    -> boolean().
@@ -128,15 +115,11 @@ add_new(T) ->
 repl(T, U) ->
     call({repl, T, U, self()}).
 
-%%% ----------------------------------------------------------
-%%% # del(Term)
-%%%
-%%% Input:  Term = term()
-%%%
-%%% Output: true
-%%%
-%%% Description: Remove any existing association of Term with self().
-%%% ----------------------------------------------------------
+%% ===========================================================================
+%% # del(Term)
+%%
+%% Remove any existing association of Term with self().
+%% ===========================================================================
 
 -spec del(any())
    -> true.
@@ -144,20 +127,16 @@ repl(T, U) ->
 del(T) ->
     call({del, T, self()}).
 
-%%% ----------------------------------------------------------
-%%% # match(Pat)
-%%%
-%%% Input:  Pat = pattern in the sense of ets:match_object/2.
-%%%
-%%% Output: list of {Term, Pid}
-%%%
-%%% Description: Return the list of associations whose Term, as specified
-%%%              to add/1 or add_new/1, matches the specified pattern.
-%%%
-%%%              Note that there's no guarantee that the returned processes
-%%%              are still alive. (Although one that isn't will soon have
-%%%              its associations removed.)
-%%% ----------------------------------------------------------
+%% ===========================================================================
+%% # match(Pat)
+%%
+%% Return the list of associations whose Term, as specified to add/1
+%% or add_new/1, matches the specified pattern.
+%%
+%% Note that there's no guarantee that the returned processes are
+%% still alive. (Although one that isn't will soon have its
+%% associations removed.)
+%% ===========================================================================
 
 -spec match(tuple())
    -> [{term(), pid()}].
@@ -165,9 +144,17 @@ del(T) ->
 match(Pat) ->
     ets:match_object(?TABLE, ?MAPPING(Pat, '_')).
 
-%% ---------------------------------------------------------
-%% EXPORTED INTERNAL FUNCTIONS
-%% ---------------------------------------------------------
+%% ===========================================================================
+%% # wait(Pat)
+%%
+%% Like match/1 but return only when the result is non-empty or fails.
+%% It's up to the caller to ensure that the wait won't be forever.
+%% ===========================================================================
+
+wait(Pat) ->
+    call({wait, Pat}).
+
+%% ===========================================================================
 
 start_link() ->
     ServerName = {local, ?SERVER},
@@ -182,7 +169,7 @@ uptime() ->
 
 %% pids/0
 %%
-%% Output: list of {Pid, [Term, ...]}
+%% Return: list of {Pid, [Term, ...]}
 
 pids() ->
     to_list(fun swap/1).
@@ -202,89 +189,100 @@ id(T) -> T.
 
 %% terms/0
 %%
-%% Output: list of {Term, [Pid, ...]}
+%% Return: list of {Term, [Pid, ...]}
 
 terms() ->
     to_list(fun id/1).
 
 swap({X,Y}) -> {Y,X}.
 
-%%% ----------------------------------------------------------
-%%% # init(Role)
-%%%
-%%% Output: {ok, State}
-%%% ----------------------------------------------------------
+%% ----------------------------------------------------------
+%% # init/1
+%% ----------------------------------------------------------
 
 init(_) ->
     ets:new(?TABLE, [bag, named_table]),
     {ok, #state{}}.
 
-%%% ----------------------------------------------------------
-%%% # handle_call(Request, From, State)
-%%% ----------------------------------------------------------
+%% ----------------------------------------------------------
+%% # handle_call/3
+%% ----------------------------------------------------------
 
-handle_call({add, Fun, Key, Pid}, _, State) ->
+handle_call(Req, From, S)
+  when not is_record(S, state) ->
+    handle_call(Req, From, upgrade(S));
+
+handle_call({add, Fun, Key, Pid}, _, S) ->
     B = Fun(?TABLE, {Key, Pid}),
     monitor(B andalso no_monitor(Pid), Pid),
-    {reply, B, State};
+    {reply, B, pending(B, S)};
 
-handle_call({del, Key, Pid}, _, State) ->
-    {reply, ets:delete_object(?TABLE, ?MAPPING(Key, Pid)), State};
+handle_call({del, Key, Pid}, _, S) ->
+    {reply, ets:delete_object(?TABLE, ?MAPPING(Key, Pid)), S};
 
-handle_call({repl, T, U, Pid}, _, State) ->
+handle_call({repl, T, U, Pid}, _, S) ->
     MatchSpec = [{?MAPPING('$1', Pid),
                   [{'=:=', '$1', {const, T}}],
                   ['$_']}],
-    {reply, repl(ets:select(?TABLE, MatchSpec), U, Pid), State};
+    {reply, repl(ets:select(?TABLE, MatchSpec), U, Pid), S};
+
+handle_call({wait, Pat}, From, #state{q = Q} = S) ->
+    case find(Pat) of
+        {ok, L} ->
+            {reply, L, S};
+        false ->
+            {noreply, S#state{q = [{From, Pat} | Q]}}
+    end;
 
-handle_call(state, _, State) ->
-    {reply, State, State};
+handle_call(state, _, S) ->
+    {reply, S, S};
 
-handle_call(uptime, _, #state{id = Time} = State) ->
-    {reply, diameter_lib:now_diff(Time), State};
+handle_call(uptime, _, #state{id = Time} = S) ->
+    {reply, diameter_lib:now_diff(Time), S};
 
-handle_call(Req, From, State) ->
+handle_call(Req, From, S) ->
     ?UNEXPECTED([Req, From]),
-    {reply, nok, State}.
+    {reply, nok, S}.
 
-%%% ----------------------------------------------------------
-%%% # handle_cast(Request, State)
-%%% ----------------------------------------------------------
+%% ----------------------------------------------------------
+%% # handle_cast/2
+%% ----------------------------------------------------------
 
-handle_cast(Msg, State)->
+handle_cast(Msg, S)->
     ?UNEXPECTED([Msg]),
-    {noreply, State}.
+    {noreply, S}.
 
-%%% ----------------------------------------------------------
-%%% # handle_info(Request, State)
-%%% ----------------------------------------------------------
+%% ----------------------------------------------------------
+%% # handle_info/2
+%% ----------------------------------------------------------
 
-handle_info({'DOWN', MRef, process, Pid, _}, State) ->
+handle_info({'DOWN', MRef, process, Pid, _}, S) ->
     ets:delete_object(?TABLE, ?MONITOR(Pid, MRef)),
     ets:match_delete(?TABLE, ?MAPPING('_', Pid)),
-    {noreply, State};
+    {noreply, S};
 
-handle_info(Info, State) ->
+handle_info(Info, S) ->
     ?UNEXPECTED([Info]),
-    {noreply, State}.
+    {noreply, S}.
 
-%%% ----------------------------------------------------------
-%%% # terminate(Reason, State)
-%%% ----------------------------------------------------------
+%% ----------------------------------------------------------
+%% # terminate/2
+%% ----------------------------------------------------------
 
 terminate(_Reason, _State)->
     ok.
 
-%%% ----------------------------------------------------------
-%%% # code_change(OldVsn, State, Extra)
-%%% ----------------------------------------------------------
+%% ----------------------------------------------------------
+%% # code_change/3
+%% ----------------------------------------------------------
 
 code_change(_OldVsn, State, _Extra) ->
     {ok, State}.
 
-%% ---------------------------------------------------------
-%% INTERNAL FUNCTIONS
-%% ---------------------------------------------------------
+%% ===========================================================================
+
+upgrade(S) ->
+    #state{} = list_to_tuple(tuple_to_list(S) ++ [[]]).
 
 monitor(true, Pid) ->
     ets:insert(?TABLE, ?MONITOR(Pid, erlang:monitor(process, Pid)));
@@ -321,6 +319,37 @@ repl([?MAPPING(_, Pid) = M], Key, Pid) ->
 repl([], _, _) ->
     false.
 
+%% pending/1
+
+pending(true, #state{q = [_|_] = Q} = S) ->
+    S#state{q = q(lists:reverse(Q), [])}; %% retain reply order
+pending(_, S) ->
+    S.
+
+q([], Q) ->
+    Q;
+q([{From, Pat} = T | Rest], Q) ->
+    case find(Pat) of
+        {ok, L} ->
+            gen_server:reply(From, L),
+            q(Rest, Q);
+        false ->
+            q(Rest, [T|Q])
+    end.
+
+%% find/1
+
+find(Pat) ->
+    try match(Pat) of
+        [] ->
+            false;
+        L ->
+            {ok, L}
+    catch
+        _:_ ->
+            {ok, []}
+    end.
+
 %% call/1
 
 call(Request) ->
diff --git a/lib/diameter/src/base/diameter_service.erl b/lib/diameter/src/base/diameter_service.erl
index 9955df42f0..91e7cbd996 100644
--- a/lib/diameter/src/base/diameter_service.erl
+++ b/lib/diameter/src/base/diameter_service.erl
@@ -64,7 +64,7 @@
 -include_lib("diameter/include/diameter.hrl").
 -include("diameter_internal.hrl").
 
-%% The "old" states maintained in this module historically.
+%% The states mirrored by peer_up/peer_down callbacks.
 -define(STATE_UP,   up).
 -define(STATE_DOWN, down).
 
@@ -107,6 +107,9 @@
 %% process.
 -define(STATE_TABLE, ?MODULE).
 
+%% The default sequence mask.
+-define(NOMASK, {0,32}).
+
 %% Workaround for dialyzer's lack of understanding of match specs.
 -type match(T)
    :: T | '_' | '$1' | '$2' | '$3' | '$4'.
@@ -114,15 +117,17 @@
 %% State of service gen_server.
 -record(state,
         {id = now(),
-         service_name,      %% as passed to start_service/2, key in ?STATE_TABLE
+         service_name,  %% as passed to start_service/2, key in ?STATE_TABLE
          service :: #diameter_service{},
-         peerT = ets_new(peers) :: ets:tid(), %% #peer{} at start_fsm
-         connT = ets_new(conns) :: ets:tid(), %% #conn{} at connection_up
-         share_peers = false :: boolean(), %% broadcast peers to remote nodes?
-         use_shared_peers = false :: boolean(),  %% use broadcasted peers?
+         peerT = ets_new(peers) :: ets:tid(),%% #peer{} at start_fsm
+         connT = ets_new(conns) :: ets:tid(),%% #conn{} at connection_up/reopen
          shared_peers = ?Dict:new(),         %% Alias -> [{TPid, Caps}, ...]
          local_peers = ?Dict:new(),          %% Alias -> [{TPid, Caps}, ...]
-         monitor = false :: false | pid()}). %% process to die with
+         monitor = false :: false | pid(),   %% process to die with
+         options
+         :: [{sequence, diameter:sequence()}  %% sequence mask
+             | {share_peers, boolean()}  %% broadcast peers to remote nodes?
+             | {use_shared_peers, boolean()}]}).%% use broadcasted peers?
 %% shared_peers reflects the peers broadcast from remote nodes. Note
 %% that the state term itself doesn't change, which is relevant for
 %% the stateless application callbacks since the state is retrieved
@@ -130,7 +135,12 @@
 %% service record is used to determine whether or not we need to call
 %% the process for a pick_peer callback.
 
-%% Record representing a watchdog process.
+%% Record representing a watchdog process as implemented by
+%% diameter_watchdog. The term "peer" here is historical, made
+%% especially confusing by the fact that a peer_ref() in the
+%% documentation is the key of a #conn{} record, not a #peer{} record.
+%% The name is also unfortunate given the meaning of peer in the
+%% Diameter sense.
 -record(peer,
         {pid  :: match(pid()),
          type :: match(connect | accept),
@@ -140,9 +150,15 @@
                  :: match(op_state() | {op_state(), wd_state()}),
          started = now(),      %% at process start
          conn = false :: match(boolean() | pid())}).
-                      %% true at accept, pid() at connection_up (connT key)
-
-%% Record representing a peer_fsm process.
+                      %% true at accepted, pid() at connection_up or reopen
+
+%% Record representing a peer process as implemented by
+%% diameter_peer_fsm. The term "conn" is historical. Despite the name
+%% here, comments refer to watchdog and peer processes, that are keys
+%% in #peer{} and #conn{} records respectively. To add to the
+%% confusion, a #request.transport is a peer process = key in a
+%% #conn{} record. The actual transport process (that the peer process
+%% knows about and that has a transport connection) isn't seen here.
 -record(conn,
         {pid   :: pid(),
          apps  :: [{0..16#FFFFFFFF, diameter:app_alias()}], %% {Id, Alias}
@@ -156,10 +172,9 @@
          handler    :: match(pid()), %% request process
          transport  :: match(pid()), %% peer process
          caps       :: match(#diameter_caps{}),
-         app        :: match(diameter:app_alias()),  %% #diameter_app.alias
-         dictionary :: match(module()),     %% #diameter_app.dictionary
-         module     :: match([module() | list()]),
-                    %% #diameter_app.module
+         app        :: match(diameter:app_alias()),%% #diameter_app.alias
+         dictionary :: match(module()),            %% #diameter_app.dictionary
+         module     :: match([module() | list()]), %% #diameter_app.module
          filter     :: match(diameter:peer_filter()),
          packet     :: match(#diameter_packet{})}).
 
@@ -170,20 +185,6 @@
          timeout = ?DEFAULT_TIMEOUT :: 0..16#FFFFFFFF,
          detach = false :: boolean()}).
 
-%% Since RFC 3588 requires that a Diameter agent not modify End-to-End
-%% Identifiers, the possibility of explicitly setting an End-to-End
-%% Identifier would be needed to be able to implement an agent in
-%% which one side of the communication is not implemented on top of
-%% diameter. For example, Diameter being sent or received encapsulated
-%% in some other protocol, or even another Diameter stack in a
-%% non-Erlang environment. (Not that this is likely to be a normal
-%% case.)
-%%
-%% The implemented solution is not an option but to respect any header
-%% values set in a diameter_header record returned from a
-%% prepare_request callback. A call to diameter:call/4 can communicate
-%% values to the callback using the 'extra' option if so desired.
-
 %%% ---------------------------------------------------------------------------
 %%% # start(SvcName)
 %%% ---------------------------------------------------------------------------
@@ -236,20 +237,20 @@ stop_transport(SvcName, [_|_] = Refs) ->
 %%% ---------------------------------------------------------------------------
 
 info(SvcName, Item) ->
-    case ets:lookup(?STATE_TABLE, SvcName) of
-        [] ->
-            undefined;
-        [S] ->
-            service_info(Item, S)
+    case find_state(SvcName) of
+        #state{} = S ->
+            service_info(Item, S);
+        false ->
+            undefined
     end.
 
 %%% ---------------------------------------------------------------------------
 %%% # receive_message(TPid, Pkt, MessageData)
 %%% ---------------------------------------------------------------------------
 
-%% Handle an incoming message in the watchdog process. This used to
-%% come through the service process but this avoids that becoming a
-%% bottleneck.
+%% Handle an incoming Diameter message in the watchdog process. This
+%% used to come through the service process but this avoids that
+%% becoming a bottleneck.
 
 receive_message(TPid, Pkt, T)
   when is_pid(TPid) ->
@@ -329,21 +330,39 @@ call_rc(_, _, Sent) ->
 %% In the process spawned for the outgoing request.
 
 call(SvcName, App, Msg, Opts, Caller) ->
-    c(ets:lookup(?STATE_TABLE, SvcName), App, Msg, Opts, Caller).
+    c(find_state(SvcName), App, Msg, Opts, Caller).
 
-c([#state{service_name = SvcName} = S], App, Msg, Opts, Caller) ->
+c(#state{service_name = Svc, options = [{_, Mask} | _]} = S,
+  App,
+  Msg,
+  Opts,
+  Caller) ->
     case find_transport(App, Msg, Opts, S) of
         {_,_,_} = T ->
-            send_request(T, Msg, Opts, Caller, SvcName);
+            send_request(T, Mask, Msg, Opts, Caller, Svc);
         false ->
             {error, no_connection};
         {error, _} = No ->
             No
     end;
 
-c([], _, _, _, _) ->
+c(false, _, _, _, _) ->
     {error, no_service}.
 
+%% find_state/1
+
+find_state(SvcName) ->
+    fs(ets:lookup(?STATE_TABLE, SvcName)).
+
+fs([#state{} = S]) ->
+    S;
+
+fs([S]) ->  %% inserted from old code
+    upgrade(S);
+
+fs([]) ->
+    false.
+
 %% make_options/1
 
 make_options(Options) ->
@@ -439,6 +458,10 @@ i(_, false) ->
 %%% # handle_call(Req, From, State)
 %%% ---------------------------------------------------------------------------
 
+handle_call(T, From, S)
+  when not is_record(S, state) ->
+    handle_call(T, From, upgrade(S));
+
 handle_call(state, _, S) ->
     {reply, S, S};
 
@@ -473,6 +496,10 @@ handle_call(stop, _From, S) ->
 %% gets the reply. We deal with this in the call to the server,
 %% stating a monitor that waits for DOWN before returning.
 
+%% Watchdog is asking for the sequence mask.
+handle_call(sequence, _From, #state{options = [{_, Mask} | _]} = S) ->
+    {reply, Mask, S};
+
 handle_call(Req, From, S) ->
     unexpected(handle_call, [Req, From], S),
     {reply, nok, S}.
@@ -489,15 +516,16 @@ handle_cast(Req, S) ->
 %%% # handle_info(Req, State)
 %%% ---------------------------------------------------------------------------
 
-handle_info(T,S) ->
+handle_info(T, #state{} = S) ->
     case transition(T,S) of
         ok ->
             {noreply, S};
-        #state{} = NS ->
-            {noreply, NS};
         {stop, Reason} ->
             {stop, {shutdown, Reason}, S}
-    end.
+    end;
+
+handle_info(T, S) ->
+    handle_info(T, upgrade(S)).
 
 %% transition/2
 
@@ -508,15 +536,26 @@ transition({accepted, Pid, TPid}, S) ->
 
 %% Peer process has a new open connection.
 transition({connection_up, Pid, T}, S) ->
-    connection_up(Pid, T, S);
+    connection_up(Pid, T, S),
+    ok;
 
-%% Peer process has left state open.
+%% Watchdog has a new connection that will be opened after DW[RA]
+%% exchange. This message was added long after connection_up, to
+%% communicate the information as soon as it's available. Leave
+%% connection_up as is it for now, duplicated information and all.
+transition({reopen, Pid, T}, S) ->
+    reopen(Pid, T, S),
+    ok;
+
+%% Watchdog has left state OKAY.
 transition({connection_down, Pid}, S) ->
-    connection_down(Pid, S);
+    connection_down(Pid, S),
+    ok;
 
-%% Peer process has returned to state open.
+%% Watchdog has returned to state OKAY.
 transition({connection_up, Pid}, S) ->
-    connection_up(Pid, S);
+    connection_up(Pid, S),
+    ok;
 
 %% Accepting transport has lost connectivity.
 transition({close, Pid}, S) ->
@@ -530,7 +569,7 @@ transition({reconnect, Pid}, S) ->
 
 %% Watchdog is sending notification of a state transition. Note that
 %% the connection_up/down messages are pre-date this message and are
-%% still used. A 'watchdog' message will follow these and communicate
+%% still used. A watchdog message will follow these and communicate
 %% the same state as was set in handling connection_up/down.
 transition({watchdog, Pid, {TPid, From, To}}, #state{service_name = SvcName,
                                                      peerT = PeerT}) ->
@@ -540,21 +579,22 @@ transition({watchdog, Pid, {TPid, From, To}}, #state{service_name = SvcName,
     insert(PeerT, P#peer{op_state = {OS, To}}),
     send_event(SvcName, {watchdog, Ref, TPid, {From, To}, {T, Opts}}),
     ok;
-%% Death of a peer process results in the removal of it's peer and any
-%% associated conn record when 'DOWN' is received (after this) but the
-%% states will be {?STATE_UP, ?WD_DOWN} for a short time. (No real
-%% problem since ?WD_* is only used in service_info.) We set ?WD_OKAY
-%% as a consequence of connection_up since we know a watchdog is
-%% coming. We can't set anything at connection_down since we don't
-%% know if the subsequent watchdog message will be ?WD_DOWN or
-%% ?WD_SUSPECT. We don't (yet) set ?STATE_* as a consequence of a
-%% watchdog message since this requires changing some of the matching
-%% on ?STATE_*.
-%%
-%% Death of a conn process results in connection_down followed by
-%% watchdog ?WD_DOWN. The latter doesn't result in the conn record
-%% being deleted since 'DOWN' from death of its peer doesn't (yet)
-%% deal with the record having been removed.
+%% Death of a watchdog process (#peer.pid) results in the removal of
+%% it's peer and any associated conn record when 'DOWN' is received
+%% (after this) but the states will be {?STATE_UP, ?WD_DOWN} for a
+%% short time. (No real problem since ?WD_* is only used in
+%% service_info.) We set ?WD_OKAY as a consequence of connection_up
+%% since we know a watchdog is coming. We can't set anything at
+%% connection_down since we don't know if the subsequent watchdog
+%% message will be ?WD_DOWN or ?WD_SUSPECT. We don't (yet) set
+%% ?STATE_* as a consequence of a watchdog message since this requires
+%% changing some of the matching on ?STATE_*.
+%%
+%% Death of a peer process process (#conn.pid, #peer.conn) results in
+%% connection_down followed by watchdog ?WD_DOWN. The latter doesn't
+%% result in the conn record being deleted since 'DOWN' from death of
+%% its watchdog doesn't (yet) deal with the record having been
+%% removed.
 
 %% Monitor process has died. Just die with a reason that tells
 %% diameter_config about the happening. If a cleaner shutdown is
@@ -562,23 +602,26 @@ transition({watchdog, Pid, {TPid, From, To}}, #state{service_name = SvcName,
 transition({'DOWN', MRef, process, _, Reason}, #state{monitor = MRef}) ->
     {stop, {monitor, Reason}};
 
-%% Local peer process has died.
+%% Local watchdog process has died.
 transition({'DOWN', _, process, Pid, Reason}, S)
   when node(Pid) == node() ->
-    peer_down(Pid, Reason, S);
+    peer_down(Pid, Reason, S),
+    ok;
 
-%% Remote service wants to know about shared transports.
+%% Remote service wants to know about shared peers.
 transition({service, Pid}, S) ->
     share_peers(Pid, S),
     ok;
 
 %% Remote service is communicating a shared peer.
 transition({peer, TPid, Aliases, Caps}, S) ->
-    remote_peer_up(TPid, Aliases, Caps, S);
+    remote_peer_up(TPid, Aliases, Caps, S),
+    ok;
 
 %% Remote peer process has died.
 transition({'DOWN', _, process, TPid, _}, S) ->
-    remote_peer_down(TPid, S);
+    remote_peer_down(TPid, S),
+    ok;
 
 %% Restart after tc expiry.
 transition({tc_timeout, T}, S) ->
@@ -592,10 +635,38 @@ transition({failover, TRef, Seqs}, S) ->
     failover(TRef, Seqs, S),
     ok;
 
+%% Ensure upgraded state is stored in state table.
+transition(upgrade, _) ->
+    ok;
+
 transition(Req, S) ->
     unexpected(handle_info, [Req], S),
     ok.
 
+%% upgrade/1
+
+upgrade({state, Id, Svc, Name, Svc, PT, CT, SB, UB, SD, LD, MPid}) ->
+    S = #state{id = Id,
+               service_name = Name,
+               service = Svc,
+               peerT = PT,
+               connT = CT,
+               shared_peers = SD,
+               local_peers = LD,
+               monitor = MPid,
+               options = [{sequence, ?NOMASK},
+                          {share_peers, SB},
+                          {use_shared_peers, UB}]},
+    upgrade_insert(S),
+    S.
+
+upgrade_insert(#state{service = #diameter_service{pid = Pid}} = S) ->
+    if Pid == self() ->
+            ets:insert(?STATE_TABLE, S);
+       true ->
+            Pid ! upgrade
+    end.
+
 %%% ---------------------------------------------------------------------------
 %%% # terminate(Reason, State)
 %%% ---------------------------------------------------------------------------
@@ -711,16 +782,20 @@ shutdown(#state{peerT = PeerT}) ->
 wait(Fun, T) ->
     diameter_lib:wait(ets:foldl(Fun, [], T)).
 
-st(#peer{conn = B}, Acc)
-  when is_boolean(B) ->
-    Acc;
-st(#peer{conn = Pid}, Acc) ->
+st(#peer{op_state = {OS,_}} = P, Acc) ->
+    st(P#peer{op_state = OS}, Acc);
+st(#peer{op_state = ?STATE_UP, conn = Pid}, Acc) ->
     Pid ! shutdown,
-    [Pid | Acc].
+    [Pid | Acc];
+st(#peer{}, Acc) ->
+    Acc.
 
-sw(#peer{pid = Pid}, Acc) ->
+sw(#peer{pid = Pid}, Acc)
+  when is_pid(Pid) ->
     exit(Pid, shutdown),
-    [Pid | Acc].
+    [Pid | Acc];
+sw(#peer{}, Acc) ->
+    Acc.
 
 %%% ---------------------------------------------------------------------------
 %%% # call_service/2
@@ -780,9 +855,8 @@ cfg_acc({SvcName, #diameter_service{applications = Apps} = Rec, Opts},
     lists:foreach(fun init_mod/1, Apps),
     S = #state{service_name = SvcName,
                service = Rec#diameter_service{pid = self()},
-               share_peers = get_value(share_peers, Opts),
-               use_shared_peers = get_value(use_shared_peers, Opts),
-               monitor = mref(get_value(monitor, Opts))},
+               monitor = mref(get_value(monitor, Opts)),
+               options = service_options(Opts)},
     {S, Acc};
 
 cfg_acc({_Ref, Type, _Opts} = T, {S, Acc})
@@ -790,15 +864,21 @@ cfg_acc({_Ref, Type, _Opts} = T, {S, Acc})
        Type == listen ->
     {S, [T | Acc]}.
 
+service_options(Opts) ->
+    [{sequence, proplists:get_value(sequence, Opts, ?NOMASK)},
+     {share_peers, get_value(share_peers, Opts)},
+     {use_shared_peers, get_value(use_shared_peers, Opts)}].
+%% The order of options is significant since we match against the list.
+
 mref(false = No) ->
     No;
 mref(P) ->
     erlang:monitor(process, P).
 
-init_shared(#state{use_shared_peers = true,
+init_shared(#state{options = [_, _, {_, true} | _],
                    service_name = Svc}) ->
     diameter_peer:notify(Svc, {service, self()});
-init_shared(#state{use_shared_peers = false}) ->
+init_shared(#state{options = [_, _, {_, false} | _]}) ->
     ok.
 
 init_mod(#diameter_app{alias = Alias,
@@ -861,9 +941,8 @@ start(Ref, Type, Opts, #state{peerT = PeerT,
     Pid.
 
 %% Note that the service record passed into the watchdog is the merged
-%% record so that each watchdog (and peer_fsm) may get a different
-%% record. This record is what is passed back into application
-%% callbacks.
+%% record so that each watchdog may get a different record. This
+%% record is what is passed back into application callbacks.
 
 s(Type, Ref, T) ->
     case diameter_watchdog:start({Type, Ref}, T) of
@@ -914,8 +993,8 @@ accepted(Pid, _TPid, #state{peerT = PeerT} = S) ->
     #peer{ref = Ref, type = accept = T, conn = false, options = Opts}
         = P
         = fetch(PeerT, Pid),
-    insert(PeerT, P#peer{conn = true}),  %% mark replacement transport started
-    start(Ref, T, Opts, S).              %% start new peer
+    insert(PeerT, P#peer{conn = true}),  %% mark replacement as started
+    start(Ref, T, Opts, S).              %% start new watchdog
 
 fetch(Tid, Key) ->
     [T] = ets:lookup(Tid, Key),
@@ -930,11 +1009,9 @@ fetch(Tid, Key) ->
 
 %%% ---------------------------------------------------------------------------
 %%% # connection_up/3
-%%%
-%%% Output: #state{}
 %%% ---------------------------------------------------------------------------
 
-%% Peer process has reached the open state.
+%% Watchdog process has reached state OKAY.
 
 connection_up(Pid, {TPid, {Caps, SApps, Pkt}}, #state{peerT = PeerT,
                                                       connT = ConnT}
@@ -949,9 +1026,29 @@ connection_up(Pid, {TPid, {Caps, SApps, Pkt}}, #state{peerT = PeerT,
     connection_up([Pkt], P#peer{conn = TPid}, C, S).
 
 %%% ---------------------------------------------------------------------------
+%%% # reopen/3
+%%% ---------------------------------------------------------------------------
+
+%% Note that this connection_up/3 rewrites the same #conn{} now
+%% written here. Both do so in case reopen has not happened in old
+%% code.
+
+reopen(Pid, {TPid, {Caps, SApps, _Pkt}}, #state{peerT = PeerT,
+                                                connT = ConnT}) ->
+    P = fetch(PeerT, Pid),
+    C = #conn{pid = TPid,
+              apps = SApps,
+              caps = Caps,
+              peer = Pid},
+
+    insert(ConnT, C),
+    #peer{op_state = {?STATE_DOWN, _}}
+        = P,
+    insert(PeerT, P#peer{op_state = {?STATE_DOWN, ?WD_REOPEN},
+                         conn = TPid}).
+
+%%% ---------------------------------------------------------------------------
 %%% # connection_up/2
-%%%
-%%% Output: #state{}
 %%% ---------------------------------------------------------------------------
 
 %% Peer process has transitioned back into the open state. Note that there
@@ -981,8 +1078,7 @@ connection_up(T, P, C, #state{peerT = PeerT,
 
     request_peer_up(TPid),
     insert_local_peer(SApps, {{TPid, Caps}, {SvcName, Apps}}, LDict),
-    report_status(up, P, C, S, T),
-    S.
+    report_status(up, P, C, S, T).
 
 insert_local_peer(SApps, T, LDict) ->
     lists:foldl(fun(A,D) -> ilp(A, T, D) end, LDict, SApps).
@@ -1024,11 +1120,9 @@ peer_cb(MFA, Alias) ->
 
 %%% ---------------------------------------------------------------------------
 %%% # connection_down/2
-%%%
-%%% Output: #state{}
 %%% ---------------------------------------------------------------------------
 
-%% Peer process has transitioned out of the open state.
+%% Watchdog has transitioned out of state OKAY.
 
 connection_down(Pid, #state{peerT = PeerT,
                             connT = ConnT}
@@ -1044,8 +1138,8 @@ connection_down(Pid, #state{peerT = PeerT,
 
 %% connection_down/3
 
-connection_down(#peer{op_state = {?STATE_DOWN, _}}, _, S) ->
-    S;
+connection_down(#peer{op_state = {?STATE_DOWN, _}}, _, _) ->
+    ok;
 
 connection_down(#peer{conn = TPid,
                       op_state = {?STATE_UP, _}}
@@ -1059,8 +1153,7 @@ connection_down(#peer{conn = TPid,
                 = S) ->
     report_status(down, P, C, S, []),
     remove_local_peer(SApps, {{TPid, Caps}, {SvcName, Apps}}, LDict),
-    request_peer_down(TPid, S),
-    S.
+    request_peer_down(TPid, S).
 
 remove_local_peer(SApps, T, LDict) ->
     lists:foldl(fun(A,D) -> rlp(A, T, D) end, LDict, SApps).
@@ -1079,11 +1172,9 @@ down_conn(Id, Alias, TC, {SvcName, Apps}) ->
 
 %%% ---------------------------------------------------------------------------
 %%% # peer_down/3
-%%%
-%%% Output: #state{}
 %%% ---------------------------------------------------------------------------
 
-%% Peer process has died.
+%% Watchdog process has died.
 
 peer_down(Pid, Reason, #state{peerT = PeerT} = S) ->
     P = fetch(PeerT, Pid),
@@ -1103,12 +1194,12 @@ closed({shutdown, {close, _TPid, Reason}},
 closed(_, _, _) ->
     ok.
 
-%% The peer has never come up ...
-peer_down(#peer{conn = B}, S)
+%% The watchdog has never reached OKAY ...
+peer_down(#peer{conn = B}, _)
   when is_boolean(B) ->
-    S;
+    ok;
 
-%% ... or it has.
+%% ... or maybe it has.
 peer_down(#peer{conn = TPid} = P, #state{connT = ConnT} = S) ->
     #conn{} = C = fetch(ConnT, TPid),
     ets:delete_object(ConnT, C),
@@ -1136,7 +1227,7 @@ restart(#peer{ref = Ref,
               started = Time}) ->
     {Time, {Ref, T, Opts}};
 
-%% ... or it has: a replacement transport has already been spawned.
+%% ... or it has: a replacement has already been spawned.
 restart(#peer{type = accept}) ->
     false.
 
@@ -1162,8 +1253,8 @@ default_tc(connect, Opts) ->
 default_tc(accept, _) ->
     0.
 
-%% Bound tc below if the peer was restarted recently to avoid
-%% continuous in case of faulty config or other problems.
+%% Bound tc below if the watchdog was restarted recently to avoid
+%% continuous restarted in case of faulty config or other problems.
 tc(Time, Tc) ->
     choose(Tc > ?RESTART_TC
              orelse timer:now_diff(now(), Time) > 1000*?RESTART_TC,
@@ -1285,7 +1376,7 @@ cm([_,_|_], _, _, _) ->
     multiple.
 
 %%% ---------------------------------------------------------------------------
-%%% # send_request/5
+%%% # send_request/6
 %%% ---------------------------------------------------------------------------
 
 %% Send an outgoing request in its dedicated process.
@@ -1298,11 +1389,11 @@ cm([_,_|_], _, _, _) ->
 %% The mod field of the #diameter_app{} here includes any extra
 %% arguments passed to diameter:call/2.
 
-send_request({TPid, Caps, App} = T, Msg, Opts, Caller, SvcName) ->
+send_request({TPid, Caps, App} = T, Mask, Msg, Opts, Caller, SvcName) ->
     #diameter_app{module = ModX}
         = App,
 
-    Pkt = make_request_packet(Msg),
+    Pkt = make_prepare_packet(Mask, Msg),
 
     send_req(cb(ModX, prepare_request, [Pkt, SvcName, {TPid, Caps}]),
              Pkt,
@@ -1313,7 +1404,7 @@ send_request({TPid, Caps, App} = T, Msg, Opts, Caller, SvcName) ->
              []).
 
 send_req({send, P}, Pkt, T, Opts, Caller, SvcName, Fs) ->
-    send_request(make_request_packet(P, Pkt), T, Opts, Caller, SvcName, Fs);
+    send_req(make_request_packet(P, Pkt), T, Opts, Caller, SvcName, Fs);
 
 send_req({discard, Reason} , _, _, _, _, _, _) ->
     {error, Reason};
@@ -1327,48 +1418,60 @@ send_req({eval_packet, RC, F}, Pkt, T, Opts, Caller, SvcName, Fs) ->
 send_req(E, _, {_, _, App}, _, _, _, _) ->
     ?ERROR({invalid_return, prepare_request, App, E}).
 
-%% make_request_packet/1
+%% make_prepare_packet/2
 %%
 %% Turn an outgoing request as passed to call/4 into a diameter_packet
 %% record in preparation for a prepare_request callback.
 
-make_request_packet(Bin)
+make_prepare_packet(_, Bin)
   when is_binary(Bin) ->
     #diameter_packet{header = diameter_codec:decode_header(Bin),
                      bin = Bin};
 
-make_request_packet(#diameter_packet{msg = [#diameter_header{} = Hdr | Avps]}
-                    = Pkt) ->
-    Pkt#diameter_packet{msg = [make_request_header(Hdr) | Avps]};
+make_prepare_packet(Mask, #diameter_packet{msg = [#diameter_header{} = Hdr
+                                                  | Avps]}
+                          = Pkt) ->
+    Pkt#diameter_packet{msg = [make_prepare_header(Mask, Hdr) | Avps]};
 
-make_request_packet(#diameter_packet{header = Hdr} = Pkt) ->
-    Pkt#diameter_packet{header = make_request_header(Hdr)};
+make_prepare_packet(Mask, #diameter_packet{header = Hdr} = Pkt) ->
+    Pkt#diameter_packet{header = make_prepare_header(Mask, Hdr)};
 
-make_request_packet(Msg) ->
-    make_request_packet(#diameter_packet{msg = Msg}).
+make_prepare_packet(Mask, Msg) ->
+    make_prepare_packet(Mask, #diameter_packet{msg = Msg}).
 
-%% make_request_header/1
+%% make_prepare_header/1
 
-make_request_header(undefined) ->
-    Seq = diameter_session:sequence(),
-    make_request_header(#diameter_header{end_to_end_id = Seq,
+make_prepare_header(Mask, undefined) ->
+    Seq = diameter_session:sequence(Mask),
+    make_prepare_header(#diameter_header{end_to_end_id = Seq,
                                          hop_by_hop_id = Seq});
 
-make_request_header(#diameter_header{version = undefined} = Hdr) ->
-    make_request_header(Hdr#diameter_header{version = ?DIAMETER_VERSION});
+make_prepare_header(Mask, #diameter_header{end_to_end_id = undefined,
+                                           hop_by_hop_id = undefined}) ->
+    Seq = diameter_session:sequence(Mask),
+    make_prepare_header(#diameter_header{end_to_end_id = Seq,
+                                         hop_by_hop_id = Seq});
 
-make_request_header(#diameter_header{end_to_end_id = undefined} = H) ->
-    Seq = diameter_session:sequence(),
-    make_request_header(H#diameter_header{end_to_end_id = Seq});
+make_prepare_header(Mask, #diameter_header{end_to_end_id = undefined} = H) ->
+    Seq = diameter_session:sequence(Mask),
+    make_prepare_header(H#diameter_header{end_to_end_id = Seq});
 
-make_request_header(#diameter_header{hop_by_hop_id = undefined} = H) ->
-    Seq = diameter_session:sequence(),
-    make_request_header(H#diameter_header{hop_by_hop_id = Seq});
+make_prepare_header(Mask, #diameter_header{hop_by_hop_id = undefined} = H) ->
+    Seq = diameter_session:sequence(Mask),
+    make_prepare_header(H#diameter_header{hop_by_hop_id = Seq});
 
-make_request_header(#diameter_header{} = Hdr) ->
+make_prepare_header(_, Hdr) ->
+    make_prepare_header(Hdr).
+
+%% make_prepare_header/1
+
+make_prepare_header(#diameter_header{version = undefined} = Hdr) ->
+    make_prepare_header(Hdr#diameter_header{version = ?DIAMETER_VERSION});
+
+make_prepare_header(#diameter_header{} = Hdr) ->
     Hdr;
 
-make_request_header(T) ->
+make_prepare_header(T) ->
     ?ERROR({invalid_header, T}).
 
 %% make_request_packet/2
@@ -1378,7 +1481,7 @@ make_request_header(T) ->
 
 make_request_packet(Bin, _)
   when is_binary(Bin) ->
-    make_request_packet(Bin);
+    make_prepare_packet(false, Bin);
 
 make_request_packet(#diameter_packet{msg = [#diameter_header{} | _]}
                     = Pkt,
@@ -1390,7 +1493,7 @@ make_request_packet(#diameter_packet{msg = [#diameter_header{} | _]}
 %% This is primarily so that the end to end and hop by hop identifiers
 %% are retained.
 make_request_packet(#diameter_packet{header = Hdr} = Pkt,
-            #diameter_packet{header = Hdr0}) ->
+                    #diameter_packet{header = Hdr0}) ->
     Pkt#diameter_packet{header = fold_record(Hdr0, Hdr)};
 
 make_request_packet(Msg, Pkt) ->
@@ -1403,9 +1506,9 @@ fold_record(undefined, R) ->
 fold_record(Rec, R) ->
     diameter_lib:fold_tuple(2, Rec, R).
 
-%% send_request/6
+%% send_req/6
 
-send_request(Pkt, {TPid, Caps, App}, Opts, Caller, SvcName, Fs) ->
+send_req(Pkt, {TPid, Caps, App}, Opts, Caller, SvcName, Fs) ->
     #diameter_app{alias = Alias,
                   dictionary = Dict,
                   module = ModX,
@@ -1693,10 +1796,13 @@ request_peer_down(TPid, S) ->
 %%% recv_request/3
 %%% ---------------------------------------------------------------------------
 
-recv_request(TPid, Pkt, {ConnT, SvcName, Apps}) ->
+recv_request(TPid, Pkt, {ConnT, SvcName, Apps}) ->  %% upgrade
+    recv_request(TPid, Pkt, {ConnT, SvcName, Apps, ?NOMASK});
+
+recv_request(TPid, Pkt, {ConnT, SvcName, Apps, Mask}) ->
     try ets:lookup(ConnT, TPid) of
         [C] ->
-            recv_request(C, TPid, Pkt, SvcName, Apps);
+            recv_request(C, TPid, Pkt, SvcName, Apps, Mask);
         [] ->             %% transport has gone down
             ok
     catch
@@ -1706,7 +1812,12 @@ recv_request(TPid, Pkt, {ConnT, SvcName, Apps}) ->
 
 %% recv_request/5
 
-recv_request(#conn{apps = SApps, caps = Caps}, TPid, Pkt, SvcName, Apps) ->
+recv_request(#conn{apps = SApps, caps = Caps},
+             TPid,
+             Pkt,
+             SvcName,
+             Apps,
+             Mask) ->
     #diameter_caps{origin_host = {OH,_},
                    origin_realm = {OR,_}}
         = Caps,
@@ -1718,6 +1829,7 @@ recv_request(#conn{apps = SApps, caps = Caps}, TPid, Pkt, SvcName, Apps) ->
                  {SvcName, OH, OR},
                  TPid,
                  Apps,
+                 Mask,
                  Caps,
                  Pkt).
 
@@ -1743,20 +1855,24 @@ keyfind([Key | Rest], Pos, L) ->
             T
     end.
 
-%% recv_request/6
+%% recv_request/7
 
-recv_request({Id, Alias}, T, TPid, Apps, Caps, Pkt) ->
+recv_request({Id, Alias}, T, TPid, Apps, Mask, Caps, Pkt) ->
     #diameter_app{dictionary = Dict}
         = A
         = find_app(Alias, Apps),
-    recv_request(T, {TPid, Caps}, A, diameter_codec:decode(Id, Dict, Pkt));
+    recv_request(T,
+                 {TPid, Caps},
+                 A,
+                 Mask,
+                 diameter_codec:decode(Id, Dict, Pkt));
 %% Note that the decode is different depending on whether or not Id is
 %% ?APP_ID_RELAY.
 
 %%   DIAMETER_APPLICATION_UNSUPPORTED   3007
 %%      A request was sent for an application that is not supported.
 
-recv_request(false, T, TPid, _, _, Pkt) ->
+recv_request(false, T, TPid, _, _, _, Pkt) ->
     As = collect_avps(Pkt),
     protocol_error(3007, T, TPid, Pkt#diameter_packet{avps = As}).
 
@@ -1768,7 +1884,7 @@ collect_avps(Pkt) ->
             As
     end.
 
-%% recv_request/4
+%% recv_request/5
 
 %% Wrong number of bits somewhere in the message: reply.
 %%
@@ -1777,7 +1893,7 @@ collect_avps(Pkt) ->
 %%      set to an unrecognized value, or that is inconsistent with the
 %%      AVP's definition.
 %%
-recv_request(T, {TPid, _}, _, #diameter_packet{errors = [Bs | _]} = Pkt)
+recv_request(T, {TPid, _}, _, _, #diameter_packet{errors = [Bs | _]} = Pkt)
   when is_bitstring(Bs) ->
     protocol_error(3009, T, TPid, Pkt);
 
@@ -1792,6 +1908,7 @@ recv_request(T, {TPid, _}, _, #diameter_packet{errors = [Bs | _]} = Pkt)
 recv_request(T,
              {TPid, _},
              #diameter_app{id = Id},
+             _,
              #diameter_packet{header = #diameter_header{is_proxiable = P},
                               msg = M}
              = Pkt)
@@ -1809,6 +1926,7 @@ recv_request(T,
 recv_request(T,
              {TPid, _},
              _,
+             _,
              #diameter_packet{header = #diameter_header{is_error = true}}
              = Pkt) ->
     protocol_error(3008, T, TPid, Pkt);
@@ -1817,15 +1935,16 @@ recv_request(T,
 %% in the relay application. Don't distinguish between the two since
 %% each application has its own callback config. That is, the user can
 %% easily distinguish between the two cases.
-recv_request(T, TC, App, Pkt) ->
-    request_cb(T, TC, App, examine(Pkt)).
+recv_request(T, TC, App, Mask, Pkt) ->
+    request_cb(T, TC, App, Mask, examine(Pkt)).
 
 %% Note that there may still be errors but these aren't protocol
 %% (3xxx) errors that lead to an answer-message.
 
-request_cb({SvcName, _OH, _OR} = T, TC, App, Pkt) ->
+request_cb({SvcName, _OH, _OR} = T, TC, App, Mask, Pkt) ->
     request_cb(cb(App, handle_request, [Pkt, SvcName, TC]),
                App,
+               Mask,
                T,
                TC,
                [],
@@ -1849,7 +1968,7 @@ examine(#diameter_packet{errors = Es} = Pkt) ->
     Pkt#diameter_packet{errors = [5011 | Es]}.
 %% It's odd/unfortunate that this isn't a protocol error.
 
-%% request_cb/6
+%% request_cb/7
 
 %% A reply may be an answer-message, constructed either here or by
 %% the handle_request callback. The header from the incoming request
@@ -1859,13 +1978,14 @@ examine(#diameter_packet{errors = Es} = Pkt) ->
 request_cb({reply, Ans},
            #diameter_app{dictionary = Dict},
            _,
+           _,
            {TPid, _},
            Fs,
            Pkt) ->
     reply(Ans, Dict, TPid, Fs, Pkt);
 
 %% An 3xxx result code, for which the E-bit is set in the header.
-request_cb({protocol_error, RC}, _, T, {TPid, _}, Fs, Pkt)
+request_cb({protocol_error, RC}, _, _, T, {TPid, _}, Fs, Pkt)
   when 3000 =< RC, RC < 4000 ->
     protocol_error(RC, T, TPid, Fs, Pkt);
 
@@ -1873,7 +1993,7 @@ request_cb({protocol_error, RC}, _, T, {TPid, _}, Fs, Pkt)
 %% unsupported. 'noreply' is undocumented (and inappropriately named)
 %% backwards compatibility for this, protocol_error the documented
 %% alternative.
-request_cb(noreply, _, T, {TPid, _}, Fs, Pkt) ->
+request_cb(noreply, _, _, T, {TPid, _}, Fs, Pkt) ->
     protocol_error(3001, T, TPid, Fs, Pkt);
 
 %% Relay a request to another peer. This is equivalent to doing an
@@ -1894,6 +2014,7 @@ request_cb(noreply, _, T, {TPid, _}, Fs, Pkt) ->
 request_cb({A, Opts},
            #diameter_app{id = Id}
            = App,
+           Mask,
            T,
            TC,
            Fs,
@@ -1901,16 +2022,16 @@ request_cb({A, Opts},
   when A == relay, Id == ?APP_ID_RELAY;
        A == proxy, Id /= ?APP_ID_RELAY;
        A == resend ->
-    resend(Opts, App, T, TC, Fs, Pkt);
+    resend(Opts, App, Mask, T, TC, Fs, Pkt);
 
-request_cb(discard, _, _, _, _, _) ->
+request_cb(discard, _, _, _, _, _, _) ->
     ok;
 
-request_cb({eval_packet, RC, F}, App, T, TC, Fs, Pkt) ->
-    request_cb(RC, App, T, TC, [F|Fs], Pkt);
+request_cb({eval_packet, RC, F}, App, Mask, T, TC, Fs, Pkt) ->
+    request_cb(RC, App, Mask, T, TC, [F|Fs], Pkt);
 
-request_cb({eval, RC, F}, App, T, TC, Fs, Pkt) ->
-    request_cb(RC, App, T, TC, Pkt, Fs),
+request_cb({eval, RC, F}, App, Mask, T, TC, Fs, Pkt) ->
+    request_cb(RC, App, Mask, T, TC, Pkt, Fs),
     diameter_lib:eval(F).
 
 %% protocol_error/5
@@ -1925,20 +2046,19 @@ protocol_error(RC, {_, OH, OR}, TPid, Fs, Pkt) ->
 protocol_error(RC, T, TPid, Pkt) ->
     protocol_error(RC, T, TPid, [], Pkt).
 
-%% resend/6
+%% resend/7
 %%
 %% Resend a message as a relay or proxy agent.
 
 resend(Opts,
        #diameter_app{} = App,
+       Mask,
        {_SvcName, OH, _OR} = T,
        {_TPid, _Caps} = TC,
        Fs,
        #diameter_packet{avps = Avps} = Pkt) ->
     {Code, _Flags, Vid} = ?BASE:avp_header('Route-Record'),
-    resend(is_loop(Code, Vid, OH, Avps), Opts, App, T, TC, Fs, Pkt).
-
-%% resend/7
+    resend(is_loop(Code, Vid, OH, Avps), Opts, App, Mask, T, TC, Fs, Pkt).
 
 %%   DIAMETER_LOOP_DETECTED             3005
 %%      An agent detected a loop while trying to get the message to the
@@ -1946,7 +2066,7 @@ resend(Opts,
 %%      if one is available, but the peer reporting the error has
 %%      identified a configuration problem.
 
-resend(true, _, _, T, {TPid, _}, Fs, Pkt) ->  %% Route-Record loop
+resend(true, _, _, _, T, {TPid, _}, Fs, Pkt) ->  %% Route-Record loop
     protocol_error(3005, T, TPid, Fs, Pkt);
 
 %% 6.1.8.  Relaying and Proxying Requests
@@ -1958,6 +2078,7 @@ resend(true, _, _, T, {TPid, _}, Fs, Pkt) ->  %% Route-Record loop
 resend(false,
        Opts,
        App,
+       Mask,
        {SvcName, _, _} = T,
        {TPid, #diameter_caps{origin_host = {_, OH}}},
        Fs,
@@ -1965,7 +2086,7 @@ resend(false,
                         avps = Avps}
        = Pkt) ->
     Route = #diameter_avp{data = {?BASE, 'Route-Record', OH}},
-    Seq = diameter_session:sequence(),
+    Seq = diameter_session:sequence(Mask),
     Hdr = Hdr0#diameter_header{hop_by_hop_id = Seq},
     Msg = [Hdr, Route | Avps],
     resend(call(SvcName, App, Msg, Opts), T, TPid, Fs, Pkt).
@@ -2118,7 +2239,7 @@ rc([MsgName | _], {'Result-Code' = K, RC} = T, Dict) ->
 
 rc(Rec, T, Dict) ->
     rc([Dict:rec2msg(element(1, Rec))], T, Dict).
-    
+
 %% failed_avp/3
 
 failed_avp(_, [] = No, _) ->
@@ -2354,7 +2475,7 @@ a(#diameter_packet{errors = Es} = Pkt, SvcName, AE, #request{transport = TPid,
   when [] == Es;
        callback == AE ->
     cb(Req, handle_answer, [Pkt, msg(P), SvcName, {TPid, Caps}]);
-    
+
 a(Pkt, SvcName, report, Req) ->
     x(errors, handle_answer, [SvcName, Req, Pkt]);
 
@@ -2516,7 +2637,7 @@ send_event(#diameter_event{service = SvcName} = E) ->
 %%% # share_peer/5
 %%% ---------------------------------------------------------------------------
 
-share_peer(up, Caps, Aliases, TPid, #state{share_peers = true,
+share_peer(up, Caps, Aliases, TPid, #state{options = [_, {_, true} | _],
                                            service_name = Svc}) ->
     diameter_peer:notify(Svc, {peer, TPid, Aliases, Caps});
 
@@ -2527,11 +2648,11 @@ share_peer(_, _, _, _, _) ->
 %%% # share_peers/2
 %%% ---------------------------------------------------------------------------
 
-share_peers(Pid, #state{share_peers = true,
+share_peers(Pid, #state{options = [_, {_, true} | _],
                         local_peers = PDict}) ->
     ?Dict:fold(fun(A,Ps,ok) -> sp(Pid, A, Ps), ok end, ok, PDict);
 
-share_peers(_, #state{share_peers = false}) ->
+share_peers(_, _) ->
     ok.
 
 sp(Pid, Alias, Peers) ->
@@ -2541,39 +2662,31 @@ sp(Pid, Alias, Peers) ->
 %%% # remote_peer_up/4
 %%% ---------------------------------------------------------------------------
 
-remote_peer_up(Pid, Aliases, Caps, #state{use_shared_peers = true,
+remote_peer_up(Pid, Aliases, Caps, #state{options = [_, _, {_, true} | _],
                                           service = Svc,
-                                          shared_peers = PDict}
-                                   = S) ->
+                                          shared_peers = PDict}) ->
     #diameter_service{applications = Apps} = Svc,
-    Update = lists:filter(fun(A) ->
-                                  lists:keymember(A, #diameter_app.alias, Apps)
-                          end,
-                          Aliases),
-    S#state{shared_peers = rpu(Pid, Caps, PDict, Update)};
+    Key = #diameter_app.alias,
+    As = lists:filter(fun(A) -> lists:keymember(A, Key, Apps) end, Aliases),
+    rpu(Pid, Caps, PDict, As);
 
-remote_peer_up(_, _, _, #state{use_shared_peers = false} = S) ->
-    S.
+remote_peer_up(_, _, _, #state{options = [_, _, {_, false} | _]}) ->
+    ok.
 
 rpu(_, _, PDict, []) ->
     PDict;
 rpu(Pid, Caps, PDict, Aliases) ->
     erlang:monitor(process, Pid),
     T = {Pid, Caps},
-    lists:foldl(fun(A,D) -> ?Dict:append(A, T, D) end,
-                PDict,
-                Aliases).
+    lists:foreach(fun(A) -> ?Dict:append(A, T, PDict) end, Aliases).
 
 %%% ---------------------------------------------------------------------------
 %%% # remote_peer_down/2
 %%% ---------------------------------------------------------------------------
 
-remote_peer_down(Pid, #state{use_shared_peers = true,
-                             shared_peers = PDict}
-                      = S) ->
-    S#state{shared_peers = lists:foldl(fun(A,D) -> rpd(Pid, A, D) end,
-                                       PDict,
-                                       ?Dict:fetch_keys(PDict))}.
+remote_peer_down(Pid, #state{options = [_, _, {_, true} | _],
+                             shared_peers = PDict}) ->
+    lists:foreach(fun(A) -> rpd(Pid, A, PDict) end, ?Dict:fetch_keys(PDict)).
 
 rpd(Pid, Alias, PDict) ->
     ?Dict:update(Alias, fun(Ps) -> lists:keydelete(Pid, 1, Ps) end, PDict).
@@ -2898,7 +3011,8 @@ transports(#state{peerT = PeerT}) ->
 -define(ALL_INFO, [capabilities,
                    applications,
                    transport,
-                   pending]).
+                   pending,
+                   options]).
 
 %% The rest.
 -define(OTHER_INFO, [connections,
@@ -2975,6 +3089,7 @@ complete_info(Item, #state{service = Svc} = S) ->
         capabilities -> service_info(?CAP_INFO, S);
         applications -> info_apps(S);
         transport    -> info_transport(S);
+        options      -> info_options(S);
         pending      -> info_pending(S);
         keys         -> ?ALL_INFO ++ ?CAP_INFO ++ ?OTHER_INFO;
         all          -> service_info(?ALL_INFO, S);
@@ -3074,6 +3189,9 @@ peer_acc(ConnT, Acc, #peer{pid = Pid,
                  | info_conn(ConnT, TPid, WS /= ?WD_DOWN)],
                 Acc).
 
+info_conn(ConnT, [TPid], B) ->
+    info_conn(ConnT, TPid, B);
+
 info_conn(ConnT, TPid, true)
   when is_pid(TPid) ->
     try ets:lookup(ConnT, TPid) of
@@ -3216,3 +3334,8 @@ peer_acc(Peer, {PeerD, RefD}) ->
     [{TPid, _}, [{origin_host, {_, OH}} | _]]
         = [proplists:get_value(K, Peer) || K <- [peer, caps]],
     {dict:append(OH, Peer, PeerD), dict:append(OH, TPid, RefD)}.
+
+%% info_options/1
+
+info_options(S) ->
+    S#state.options.
diff --git a/lib/diameter/src/base/diameter_session.erl b/lib/diameter/src/base/diameter_session.erl
index 4c468f207c..3b236f109a 100644
--- a/lib/diameter/src/base/diameter_session.erl
+++ b/lib/diameter/src/base/diameter_session.erl
@@ -1,7 +1,7 @@
 %%
 %% %CopyrightBegin%
 %%
-%% Copyright Ericsson AB 2010-2011. All Rights Reserved.
+%% Copyright Ericsson AB 2010-2012. 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
@@ -20,6 +20,7 @@
 -module(diameter_session).
 
 -export([sequence/0,
+         sequence/1,
          session_id/1,
          origin_state_id/0]).
 
@@ -30,7 +31,7 @@
 -define(INT32, 16#FFFFFFFF).
 
 %% ---------------------------------------------------------------------------
-%% # sequence/0
+%% # sequence/0-1
 %%
 %% Output: 32-bit
 %% ---------------------------------------------------------------------------
@@ -77,6 +78,15 @@ sequence() ->
     Instr = {_Pos = 2, _Incr = 1, _Threshold = ?INT32, _SetVal = 0},
     ets:update_counter(diameter_sequence, sequence, Instr).
 
+-spec sequence(diameter:sequence())
+   -> diameter:'Unsigned32'().
+
+sequence({_,32}) ->
+    sequence();
+
+sequence({H,N}) ->
+    (H bsl N) bor (sequence() band (1 bsl N - 1)).
+
 %% ---------------------------------------------------------------------------
 %% # origin_state_id/0
 %% ---------------------------------------------------------------------------
diff --git a/lib/diameter/src/base/diameter_watchdog.erl b/lib/diameter/src/base/diameter_watchdog.erl
index 53f5f42396..b37a1a10e9 100644
--- a/lib/diameter/src/base/diameter_watchdog.erl
+++ b/lib/diameter/src/base/diameter_watchdog.erl
@@ -43,6 +43,7 @@
 -include("diameter_internal.hrl").
 
 -define(DEFAULT_TW_INIT, 30000). %% RFC 3539 ch 3.4.1
+-define(NOMASK, {0,32}).  %% default sequence mask
 
 -record(watchdog,
         {%% PCB - Peer Control Block; see RFC 3539, Appendix A
@@ -56,7 +57,8 @@
          parent = self() :: pid(),
          transport       :: pid() | undefined,
          tref :: reference(), %% reference for current watchdog timer
-         message_data}).   %% term passed into diameter_service with message
+         message_data,        %% term passed into diameter_service with message
+         sequence :: diameter:sequence()}).  %% mask
 
 %% start/2
 %%
@@ -118,12 +120,20 @@ make_state({T, Pid, {RecvData,
     random:seed(now()),
     putr(restart, {T, Opts, Svc}),  %% save seeing it in trace
     putr(dwr, dwr(Caps)),           %%
+    {_,_} = Mask = call(Pid, sequence),
     #watchdog{parent = Pid,
-              transport = monitor(diameter_peer_fsm:start(T, Opts, Svc)),
+              transport = monitor(diameter_peer_fsm:start(T,
+                                                          Opts,
+                                                          {Mask, Svc})),
               tw = proplists:get_value(watchdog_timer,
                                        Opts,
                                        ?DEFAULT_TW_INIT),
-              message_data = {RecvData, SvcName, Apps}}.
+              message_data = {RecvData, SvcName, Apps, Mask},
+              sequence = Mask}.
+
+%% Retrieve the sequence mask from the parent from the parent, rather
+%% than having it passed into init/1, for upgrade reasons: the call to
+%% diameter_service:receive_message/3 passes back the mask.
 
 %% handle_call/3
 
@@ -137,7 +147,7 @@ handle_cast(_, State) ->
 
 %% handle_info/2
 
-handle_info(T, State) ->
+handle_info(T, #watchdog{} = State) ->
     case transition(T, State) of
         ok ->
             {noreply, State};
@@ -148,7 +158,11 @@ handle_info(T, State) ->
             ?LOG(stop, T),
             event(State, State#watchdog{status = down}),
             {stop, {shutdown, T}, State}
-    end.
+    end;
+
+handle_info(T, S) ->  %% upgrade
+    handle_info(T, #watchdog{} = list_to_tuple(tuple_to_list(S)
+                                               ++ [?NOMASK])).
 
 event(#watchdog{status = T}, #watchdog{status = T}) ->
     ok;
@@ -258,12 +272,15 @@ transition({open, TPid, Hosts, T} = Open,
 
 transition({open = P, TPid, _Hosts, T},
            #watchdog{transport = TPid,
+                     parent = Pid,
                      status = down}
            = S) ->
     %% Store the info we need to notify the parent to reopen the
     %% connection after the requisite DWA's are received, at which
-    %% time we eraser(open).
+    %% time we eraser(open). The reopen message is a later addition,
+    %% to communicate the new capabilities as soon as they're known.
     putr(P, {TPid, T}),
+    Pid ! {reopen, self(), {TPid, T}},
     set_watchdog(send_watchdog(S#watchdog{status = reopen,
                                           num_dwa = 0}));
 
@@ -312,6 +329,15 @@ transition({state, Pid}, #watchdog{status = S}) ->
 
 %% ===========================================================================
 
+%% Only call "upwards", to the parent service.
+call(Pid, Req) ->
+    try
+        gen_server:call(Pid, Req, infinity)
+    catch
+        exit: Reason ->
+            exit({shutdown, {Req, Reason}})
+    end.
+
 monitor(Pid) ->
     erlang:monitor(process, Pid),
     Pid.
@@ -325,10 +351,16 @@ getr(Key) ->
 eraser(Key) ->
     erase({?MODULE, Key}).
 
-%% encode/1
+%% encode/2
 
-encode(Msg) ->
-    #diameter_packet{bin = Bin} = diameter_codec:encode(?BASE, Msg),
+encode(Msg, Mask) ->
+    Seq = diameter_session:sequence(Mask),
+    Hdr = #diameter_header{version = ?DIAMETER_VERSION,
+                           end_to_end_id = Seq,
+                           hop_by_hop_id = Seq},
+    Pkt = #diameter_packet{header = Hdr,
+                           msg = Msg},
+    #diameter_packet{bin = Bin} = diameter_codec:encode(?BASE, Pkt),
     Bin.
 
 %% okay/2
@@ -400,9 +432,10 @@ close(#watchdog{parent = Pid}) ->
 %% send_watchdog/1
 
 send_watchdog(#watchdog{pending = false,
-                        transport = TPid}
+                        transport = TPid,
+                        sequence = Mask}
               = S) ->
-    TPid ! {send, encode(getr(dwr))},
+    TPid ! {send, encode(getr(dwr), Mask)},
     ?LOG(send, 'DWR'),
     S#watchdog{pending = true}.
 
@@ -606,9 +639,13 @@ restart(S) ->
 %% it's actually in state down rather then initial when receiving
 %% notification of an open connection.
 
-restart({{connect, _} = T, Opts, Svc}, #watchdog{parent = Pid} = S) ->
+restart({{connect, _} = T, Opts, Svc}, #watchdog{parent = Pid,
+                                                 sequence = Mask}
+                                       = S) ->
     Pid ! {reconnect, self()},
-    S#watchdog{transport = monitor(diameter_peer_fsm:start(T, Opts, Svc))};
+    S#watchdog{transport = monitor(diameter_peer_fsm:start(T,
+                                                           Opts,
+                                                           {Mask, Svc}))};
 restart({{accept, _}, _, _}, S) ->
     S.
 %% Don't currently use Opts/Svc in the accept case but having them in