Implement service_opt() restrict_connections

5 files changed, 147 insertions, 40 deletions

diff --git a/lib/diameter/src/base/diameter.erl b/lib/diameter/src/base/diameter.erl
index d60510db7d..3e3a6be0ef 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,
+              restriction/0,
               sequence/0,
               app_alias/0,
               service_name/0,
@@ -284,11 +285,19 @@ call(SvcName, App, Message) ->
 -type sequence()
    :: {'Unsigned32'(), 0..32}.
 
+-type restriction()
+   :: false
+    | node
+    | nodes
+    | [node()]
+    | evaluable().
+
 %% Options passed to start_service/2
 
 -type service_opt()
    :: capability()
     | {application, [application_opt()]}
+    | {restrict_connections, restriction()}
     | {sequence, sequence() | evaluable()}.
 
 -type application_opt()
diff --git a/lib/diameter/src/base/diameter_config.erl b/lib/diameter/src/base/diameter_config.erl
index fc37ca8541..63d28f25a2 100644
--- a/lib/diameter/src/base/diameter_config.erl
+++ b/lib/diameter/src/base/diameter_config.erl
@@ -555,7 +555,8 @@ make_config(SvcName, Opts) ->
     Os = split(Opts, fun opt/2, [{false, share_peers},
                                  {false, use_shared_peers},
                                  {false, monitor},
-                                 {?NOMASK, sequence}]),
+                                 {?NOMASK, sequence},
+                                 {nodes, restrict_connections}]),
     %% share_peers and use_shared_peers are currently undocumented.
 
     #service{name = SvcName,
@@ -579,15 +580,33 @@ opt(monitor, P)
   when is_pid(P) ->
     P;
 
+opt(restrict_connections, T)
+  when T == node;
+       T == nodes;
+       T == [];
+       is_atom(hd(T)) ->
+    T;
+
+opt(restrict_connections = K, F) ->
+    try diameter_lib:eval(F) of  %% no guarantee that it won't fail later
+        Nodes when is_list(Nodes) ->
+            F;
+        V ->
+            ?THROW({value, {K,V}})
+    catch
+        E:R ->
+            ?THROW({value, {K, E, R, ?STACK}})
+    end;
+
 opt(sequence, {_,_} = T) ->
     sequence(T);
 
-opt(sequence, F) ->
+opt(sequence = K, F) ->
     try diameter_lib:eval(F) of
         T -> sequence(T)
     catch
         E:R ->
-            ?THROW({value, {sequence, E, R, ?STACK}})
+            ?THROW({value, {K, E, R, ?STACK}})
     end;
             
 opt(K, _) ->
diff --git a/lib/diameter/src/base/diameter_peer_fsm.erl b/lib/diameter/src/base/diameter_peer_fsm.erl
index 8ce6ea847a..297a5d7709 100644
--- a/lib/diameter/src/base/diameter_peer_fsm.erl
+++ b/lib/diameter/src/base/diameter_peer_fsm.erl
@@ -60,6 +60,7 @@
 -define(Q_KEY, q).           %% transport start queue
 -define(START_KEY, start).   %% start of connected transport
 -define(SEQUENCE_KEY, mask). %% mask for sequence numbers
+-define(RESTRICT_KEY, restrict). %% nodes for connection check
 
 %% The default sequence mask.
 -define(NOMASK, {0,32}).
@@ -126,7 +127,9 @@
 %%% ---------------------------------------------------------------------------
 
 -spec start(T, [Opt], #diameter_service{}  %% from old code
-                    | {diameter:sequence(), #diameter_service{}})
+                    | {diameter:sequence(),
+                       diameter:restriction(),
+                       #diameter_service{}})
    -> pid()
  when T   :: {connect|accept, diameter:transport_ref()},
       Opt :: diameter:transport_opt().
@@ -157,11 +160,11 @@ init(T) ->
     gen_server:enter_loop(?MODULE, [], i(T)).
 
 i({WPid, Type, Opts, #diameter_service{} = Svc}) ->  %% from old code
-    i({WPid, Type, Opts, {?NOMASK, Svc}});
+    i({WPid, Type, Opts, {?NOMASK, [node() | nodes()], Svc}});
 
-i({WPid, T, Opts, {Mask, #diameter_service{applications = Apps,
-                                           capabilities = Caps}
-                         = Svc}}) ->
+i({WPid, T, Opts, {Mask, Nodes, #diameter_service{applications = Apps,
+                                                  capabilities = Caps}
+                                = Svc}}) ->
     [] /= Apps orelse ?ERROR({no_apps, T, Opts}),
     putr(?DWA_KEY, dwa(Caps)),
     {M, Ref} = T,
@@ -169,6 +172,7 @@ i({WPid, T, Opts, {Mask, #diameter_service{applications = Apps,
     {[Ts], Rest} = proplists:split(Opts, [capabilities_cb]),
     putr(?CB_KEY, {Ref, [F || {_,F} <- Ts]}),
     putr(?SEQUENCE_KEY, Mask),
+    putr(?RESTRICT_KEY, Nodes),
     erlang:monitor(process, WPid),
     {TPid, Addrs} = start_transport(T, Rest, Svc),
     #state{parent = WPid,
@@ -990,15 +994,31 @@ dpa_timer() ->
 %% Register a term and ensure it's not registered elsewhere. Note that
 %% two process that simultaneously register the same term may well
 %% both fail to do so this isn't foolproof.
+%%
+%% Everywhere is no longer everywhere, it's where a
+%% restrict_connections service_opt() specifies.
 
 register_everywhere(T) ->
-    diameter_reg:add_new(T)
-        andalso unregistered(T).
+    reg(getr(?RESTRICT_KEY), T).
+
+reg(Nodes, T) ->
+    add(lists:member(node(), Nodes), T) andalso unregistered(Nodes, T).
+
+add(true, T) ->
+    diameter_reg:add_new(T);
+add(false, T) ->
+    diameter_reg:add(T).
 
-unregistered(T) ->
-    {ResL, _} = rpc:multicall(?MODULE, match, [{node(), T}]),
+%% unregistered
+%%
+%% Ensure that the term in question isn't registered on other nodes.
+
+unregistered(Nodes, T) ->
+    {ResL, _} = rpc:multicall(Nodes, ?MODULE, match, [{node(), T}]),
     lists:all(fun(L) -> [] == L end, ResL).
 
+%% match/1
+
 match({Node, _})
   when Node == node() ->
     [];
diff --git a/lib/diameter/src/base/diameter_service.erl b/lib/diameter/src/base/diameter_service.erl
index 91e7cbd996..b4e54cc9f9 100644
--- a/lib/diameter/src/base/diameter_service.erl
+++ b/lib/diameter/src/base/diameter_service.erl
@@ -110,6 +110,9 @@
 %% The default sequence mask.
 -define(NOMASK, {0,32}).
 
+%% The default restrict_connections.
+-define(RESTRICT, nodes).
+
 %% Workaround for dialyzer's lack of understanding of match specs.
 -type match(T)
    :: T | '_' | '$1' | '$2' | '$3' | '$4'.
@@ -126,6 +129,7 @@
          monitor = false :: false | pid(),   %% process to die with
          options
          :: [{sequence, diameter:sequence()}  %% sequence mask
+             | {restrict_connections, diameter:restriction()}
              | {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
@@ -500,6 +504,10 @@ handle_call(stop, _From, S) ->
 handle_call(sequence, _From, #state{options = [{_, Mask} | _]} = S) ->
     {reply, Mask, S};
 
+%% Watchdog is asking for the nodes restriction.
+handle_call(restriction, _From, #state{options = [_,_,_,{_,R} | _]} = S) ->
+    {reply, R, S};
+
 handle_call(Req, From, S) ->
     unexpected(handle_call, [Req, From], S),
     {reply, nok, S}.
@@ -656,7 +664,8 @@ upgrade({state, Id, Svc, Name, Svc, PT, CT, SB, UB, SD, LD, MPid}) ->
                monitor = MPid,
                options = [{sequence, ?NOMASK},
                           {share_peers, SB},
-                          {use_shared_peers, UB}]},
+                          {use_shared_peers, UB},
+                          {restrict_connections, ?RESTRICT}]},
     upgrade_insert(S),
     S.
 
@@ -867,7 +876,10 @@ cfg_acc({_Ref, Type, _Opts} = T, {S, 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)}].
+     {use_shared_peers, get_value(use_shared_peers, Opts)},
+     {restrict_connections, proplists:get_value(restrict_connections,
+                                                Opts,
+                                                ?RESTRICT)}].
 %% The order of options is significant since we match against the list.
 
 mref(false = No) ->
diff --git a/lib/diameter/src/base/diameter_watchdog.erl b/lib/diameter/src/base/diameter_watchdog.erl
index b37a1a10e9..d814f1afe2 100644
--- a/lib/diameter/src/base/diameter_watchdog.erl
+++ b/lib/diameter/src/base/diameter_watchdog.erl
@@ -57,8 +57,9 @@
          parent = self() :: pid(),
          transport       :: pid() | undefined,
          tref :: reference(), %% reference for current watchdog timer
-         message_data,        %% term passed into diameter_service with message
-         sequence :: diameter:sequence()}).  %% mask
+         message_data,      %% term passed into diameter_service with message
+         sequence :: diameter:sequence(),     %% mask
+         restrict :: {diameter:restriction(), boolean()}}).
 
 %% start/2
 %%
@@ -121,15 +122,18 @@ make_state({T, Pid, {RecvData,
     putr(restart, {T, Opts, Svc}),  %% save seeing it in trace
     putr(dwr, dwr(Caps)),           %%
     {_,_} = Mask = call(Pid, sequence),
+    Restrict = call(Pid, restriction),
+    Nodes = restrict_nodes(Restrict),
     #watchdog{parent = Pid,
               transport = monitor(diameter_peer_fsm:start(T,
-                                                          Opts,
-                                                          {Mask, Svc})),
+                                                        Opts,
+                                                      {Mask, Nodes, Svc})),
               tw = proplists:get_value(watchdog_timer,
                                        Opts,
                                        ?DEFAULT_TW_INIT),
               message_data = {RecvData, SvcName, Apps, Mask},
-              sequence = Mask}.
+              sequence = Mask,
+              restrict = {Restrict, lists:member(node(), Nodes)}}.
 
 %% Retrieve the sequence mask from the parent from the parent, rather
 %% than having it passed into init/1, for upgrade reasons: the call to
@@ -160,9 +164,11 @@ handle_info(T, #watchdog{} = State) ->
             {stop, {shutdown, T}, State}
     end;
 
-handle_info(T, S) ->  %% upgrade
-    handle_info(T, #watchdog{} = list_to_tuple(tuple_to_list(S)
-                                               ++ [?NOMASK])).
+handle_info(T, S) ->
+    handle_info(T, upgrade(S)).
+
+upgrade(S) ->
+    #watchdog{} = list_to_tuple(tuple_to_list(S) ++ [?NOMASK, {nodes, true}]).
 
 event(#watchdog{status = T}, #watchdog{status = T}) ->
     ok;
@@ -255,9 +261,10 @@ transition({close, TPid, _Reason}, #watchdog{transport = TPid}) ->
 transition({open, TPid, Hosts, T} = Open,
            #watchdog{transport = TPid,
                      status = initial,
-                     parent = Pid}
+                     parent = Pid,
+                     restrict = {_, R}}
            = S) ->
-    case okay(getr(restart), Hosts) of
+    case okay(getr(restart), Hosts, R) of
         okay ->
             open(Pid, {TPid, T}),
             set_watchdog(S#watchdog{status = okay});
@@ -363,20 +370,24 @@ encode(Msg, Mask) ->
     #diameter_packet{bin = Bin} = diameter_codec:encode(?BASE, Pkt),
     Bin.
 
-%% okay/2
+%% okay/3
 
-okay({{accept, Ref}, _, _}, Hosts) ->
+okay({{accept, Ref}, _, _}, Hosts, Restrict) ->
     T = {?MODULE, connection, Ref, Hosts},
     diameter_reg:add(T),
-    okay(diameter_reg:match(T));
+    if Restrict ->
+            okay(diameter_reg:match(T));
+       true ->
+            okay
+    end;
 %% Register before matching so that at least one of two registering
-%% processes will match the other. (Which can't happen as long as
-%% diameter_peer_fsm guarantees at most one open connection to the same
-%% peer.)
+%% processes will match the other.
 
-okay({{connect, _}, _, _}, _) ->
+okay({{connect, _}, _, _}, _, _) ->
     okay.
 
+%% okay/2
+
 %% The peer hasn't been connected recently ...
 okay([{_,P}]) ->
     P = self(),  %% assert
@@ -633,23 +644,40 @@ restart(#watchdog{transport = undefined} = S) ->
 restart(S) ->
     S.
 
+%% restart/2
+%%
 %% Only restart the transport in the connecting case. For an accepting
-%% transport, we've registered the peer connection when leaving state
-%% initial and this is used by a new accepting process to realize that
-%% it's actually in state down rather then initial when receiving
-%% notification of an open connection.
+%% transport, there's no guarantee that an accepted connection in a
+%% restarted transport if from the peer we've lost contact with so
+%% have to be prepared for another watchdog to handle it. This is what
+%% the diameter_reg registration in this module is for: the peer
+%% connection is registered when leaving state initial and this is
+%% used by a new accepting watchdog to realize that it's actually in
+%% state down rather then initial when receiving notification of an
+%% open connection.
 
 restart({{connect, _} = T, Opts, Svc}, #watchdog{parent = Pid,
-                                                 sequence = Mask}
+                                                 sequence = Mask,
+                                                 restrict = {R,_}}
                                        = S) ->
     Pid ! {reconnect, self()},
+    Nodes = restrict_nodes(R),
     S#watchdog{transport = monitor(diameter_peer_fsm:start(T,
-                                                           Opts,
-                                                           {Mask, Svc}))};
+                                                         Opts,
+                                                       {Mask, Nodes, Svc})),
+               restrict = {R, lists:member(node(), Nodes)}};
+
+%% No restriction on the number of connections to the same peer: just
+%% die. Note that a state machine never enters state REOPEN in this
+%% case.
+restart({{accept, _}, _, _}, #watchdog{restrict = {_, false}}) ->
+    stop;
+
+%% Otherwise hang around until told to die.
 restart({{accept, _}, _, _}, S) ->
     S.
-%% Don't currently use Opts/Svc in the accept case but having them in
-%% the process dictionary is helpful if the process dies unexpectedly.
+
+%% Don't currently use Opts/Svc in the accept case.
 
 %% dwr/1
 
@@ -659,3 +687,22 @@ dwr(#diameter_caps{origin_host = OH,
     ['DWR', {'Origin-Host', OH},
             {'Origin-Realm', OR},
             {'Origin-State-Id', OSI}].
+
+%% restrict_nodes/1
+
+restrict_nodes(false) ->
+    [];
+
+restrict_nodes(nodes) ->
+    [node() | nodes()];
+
+restrict_nodes(node) ->
+    [node()];
+
+restrict_nodes(Nodes)
+  when [] == Nodes;
+       is_atom(hd(Nodes)) ->
+    Nodes;
+
+restrict_nodes(F) ->
+    diameter_lib:eval(F).