Let candidate peers be passed to diameter:call/4

To solve the problem of being able to send messages to a peer that
hasn't advertised support for the application in question, as discussed
in the parent commit. diameter:call/4 can be passed 'peer' options to
identify candidates, and the only requirement is that an appropriate
dictionary be configured for encode. Filters are applied as if
candidates had been selected by advertised application.

3 files changed, 38 insertions, 24 deletions

diff --git a/lib/diameter/src/base/diameter.erl b/lib/diameter/src/base/diameter.erl
index 253f64133c..bd92e16fba 100644
--- a/lib/diameter/src/base/diameter.erl
+++ b/lib/diameter/src/base/diameter.erl
@@ -406,4 +406,5 @@ call(SvcName, App, Message) ->
    :: {extra, list()}
     | {filter, peer_filter()}
     | {timeout, 'Unsigned32'()}
+    | {peer, peer_ref()}
     | detach.
diff --git a/lib/diameter/src/base/diameter_service.erl b/lib/diameter/src/base/diameter_service.erl
index be50e87179..4fc49309b5 100644
--- a/lib/diameter/src/base/diameter_service.erl
+++ b/lib/diameter/src/base/diameter_service.erl
@@ -282,7 +282,8 @@ whois(SvcName) ->
                   | {alias, diameter:app_alias()},
       Opts :: {fun((Dict :: module()) -> [term()]),
                diameter:peer_filter(),
-               Xtra :: list()},
+               Xtra :: list(),
+               [diameter:peer_ref()]},
       TPid :: pid(),
       Caps :: #diameter_caps{},
       App  :: #diameter_app{},
@@ -310,10 +311,10 @@ pick(#state{options = SvcOpts}
      = S,
      #diameter_app{module = ModX, dictionary = Dict}
      = App0,
-     {DestF, Filter, Xtra}) ->
+     {DestF, Filter, Xtra, TPids}) ->
     App = App0#diameter_app{module = ModX ++ Xtra},
     [_,_] = RealmAndHost = diameter_lib:eval([DestF, Dict]),
-    case pick_peer(App, RealmAndHost, Filter, S) of
+    case pick_peer(App, RealmAndHost, [Filter | TPids], S) of
         {_TPid, _Caps} = TC ->
             {{TC, App}, SvcOpts};
         false = No ->
@@ -1522,8 +1523,14 @@ pick_peer(Local,
 
 %% peers/4
 
-peers(Alias, RH, Filter, T) ->
-    filter(Alias, RH, Filter, T, true).
+%% No peer options pointing at specific peers: search for them.
+peers(Alias, RH, [Filter], T) ->
+    filter(Alias, RH, Filter, T, true);
+
+%% Or just lookup.
+peers(_Alias, RH, [Filter | TPids], {PeerT, _AppT, _IdentT}) ->
+    {Ts, _} = filter(caps(PeerT, TPids), RH, Filter),
+    Ts.
 
 %% filter/5
 %%
diff --git a/lib/diameter/src/base/diameter_traffic.erl b/lib/diameter/src/base/diameter_traffic.erl
index 54f39afbf0..7a5a3d662a 100644
--- a/lib/diameter/src/base/diameter_traffic.erl
+++ b/lib/diameter/src/base/diameter_traffic.erl
@@ -64,7 +64,8 @@
 
 %% Record diameter:call/4 options are parsed into.
 -record(options,
-        {filter = none  :: diameter:peer_filter(),
+        {peers = []     :: [diameter:peer_ref()],
+         filter = none  :: diameter:peer_filter(),
          extra = []     :: list(),
          timeout = 5000 :: 0..16#FFFFFFFF,  %% for outgoing requests
          detach = false :: boolean()}).
@@ -1275,36 +1276,41 @@ send_R(SvcName, AppOrAlias, Msg, CallOpts, Caller) ->
 %% make_options/1
 
 make_options(Options) ->
-    make_opts(Options, false, [], none, 5000).
+    make_opts(Options, [], false, [], none, 5000).
 
 %% Do our own recursion since this is faster than a lists:foldl/3
 %% setting elements in an #options{} accumulator.
 
-make_opts([], Detach, Extra, Filter, Tmo) ->
-    #options{detach = Detach,
+make_opts([], Peers, Detach, Extra, Filter, Tmo) ->
+    #options{peers = lists:reverse(Peers),
+             detach = Detach,
              extra = Extra,
              filter = Filter,
              timeout = Tmo};
 
-make_opts([{timeout, Tmo} | Rest], Detach, Extra, Filter, _)
+make_opts([{timeout, Tmo} | Rest], Peers, Detach, Extra, Filter, _)
   when is_integer(Tmo), 0 =< Tmo ->
-    make_opts(Rest, Detach, Extra, Filter, Tmo);
+    make_opts(Rest, Peers, Detach, Extra, Filter, Tmo);
 
-make_opts([{filter, F} | Rest], Detach, Extra, none, Tmo) ->
-    make_opts(Rest, Detach, Extra, F, Tmo);
-make_opts([{filter, F} | Rest], Detach, Extra, {all, Fs}, Tmo) ->
-    make_opts(Rest, Detach, Extra, {all, [F|Fs]}, Tmo);
-make_opts([{filter, F} | Rest], Detach, Extra, F0, Tmo) ->
-    make_opts(Rest, Detach, Extra, {all, [F0, F]}, Tmo);
+make_opts([{filter, F} | Rest], Peers, Detach, Extra, none, Tmo) ->
+    make_opts(Rest, Peers, Detach, Extra, F, Tmo);
+make_opts([{filter, F} | Rest], Peers, Detach, Extra, {all, Fs}, Tmo) ->
+    make_opts(Rest, Peers, Detach, Extra, {all, [F|Fs]}, Tmo);
+make_opts([{filter, F} | Rest], Peers, Detach, Extra, F0, Tmo) ->
+    make_opts(Rest, Peers, Detach, Extra, {all, [F0, F]}, Tmo);
 
-make_opts([{extra, L} | Rest], Detach, Extra, Filter, Tmo)
+make_opts([{extra, L} | Rest], Peers, Detach, Extra, Filter, Tmo)
   when is_list(L) ->
-    make_opts(Rest, Detach, Extra ++ L, Filter, Tmo);
+    make_opts(Rest, Peers, Detach, Extra ++ L, Filter, Tmo);
 
-make_opts([detach | Rest], _, Extra, Filter, Tmo) ->
-    make_opts(Rest, true, Extra, Filter, Tmo);
+make_opts([detach | Rest], Peers, _, Extra, Filter, Tmo) ->
+    make_opts(Rest, Peers, true, Extra, Filter, Tmo);
 
-make_opts([T | _], _, _, _, _) ->
+make_opts([{peer, TPid} | Rest], Peers, Detach, Extra, Filter, Tmo)
+  when is_pid(TPid) ->
+    make_opts(Rest, [TPid | Peers], Detach, Extra, Filter, Tmo);
+
+make_opts([T | _], _, _, _, _, _) ->
     ?ERROR({invalid_option, T}).
 
 %% ---------------------------------------------------------------------------
@@ -1654,8 +1660,8 @@ pick_peer(_, _, undefined, _) ->
 pick_peer(SvcName,
           AppOrAlias,
           Msg,
-          #options{filter = Filter, extra = Xtra}) ->
-    X = {fun(D) -> get_destination(D, Msg) end, Filter, Xtra},
+          #options{peers = TPids, filter = Filter, extra = Xtra}) ->
+    X = {fun(D) -> get_destination(D, Msg) end, Filter, Xtra, TPids},
     case diameter_service:pick_peer(SvcName, AppOrAlias, X) of
         false ->
             {error, no_connection};