mgw_nat: Add ability to translate multiple signalling links

The mgw_nat_sup supervisor now starts one mgw_nat_usr process for each
MSC-STP link defined in the configuration file.  However, the actual
translation/mangling/masquerading configuration as well as runtime state
like allocated SCCP mappings is global/shared between all signalling
links.

Furthermore, a new mgw_nat_adm process is introduced to ensure config
file reloading (formerly handled by the single mgw_nat_usr) does not
have to run in the supervisor (and risk crashing it).

ebin/mgw_nat.app

@@ -2,14 +2,12 @@
 	[{description, "Media Gateway NAT"},
 	 {vsn, "1"},
 	 {modules, [mgw_nat_app, mgw_nat_sup, mgw_nat_usr, mgw_nat,
-		    sccp_masq, map_masq, sctp_handler,
+		    mgw_nat_adm, sccp_masq, map_masq, sctp_handler,
 		    mgw_nat_act_bow_onw, mgw_nat_act_vfuk_onw]},
 	 {registered, [mgw_nat_app]},
 	 {mod, {mgw_nat_app, []}},
 	 {applications, []},
 	 {env, [
-		% Specify the rewrite actor module
-		%{rewrite_act_mod, mgw_nat_act_bow_onw },
 
 		% SCCP static rewrite rules
 		{sccp_rewrite_tbl, [
@@ -27,11 +25,26 @@
 		{intern_pfx, 63},
 
 		% Example SCTP / IP config
-		{msc_local_ip, any},
-		{msc_local_port, 2904},
-		{msc_remote_ip, {172,16,1,81}},
-		{stp_remote_ip, {172,16,249,20}},
-		{stp_remote_port, 2904},
+		{sign_links, [
+			{mgw_nat_msc1, [
+				{msc_local_ip, any},
+				{msc_local_port, 2904},
+				{msc_remote_ip, {172,16,1,81}},
+				{stp_remote_ip, {172,16,249,20}},
+				{stp_remote_port, 2904},
+				% Specify the rewrite actor module
+				{rewrite_act_mod, mgw_nat_act_bow_onw }
+			]},
+			{mgw_nat_msc2, [
+				{msc_local_ip, any},
+				{msc_local_port, 2905},
+				{msc_remote_ip, {172,16,1,81}},
+				%{stp_remote_ip, {172,16,249,20}},
+				{stp_remote_port, 2905},
+				% Specify the rewrite actor module
+				{rewrite_act_mod, mgw_nat_act_bow_onw }
+			]}
+		]},
 
 		% Example MAP rewrite table
 		{map_rewrite_table, [

src/mgw_nat_adm.erl

@@ -0,0 +1,82 @@
+% Administrative process for MGW NAT
+
+% The administrative process takes care of re-loading the configuration
+% after it has been re-parsed.  This includes delivering a reload_config
+% signal to all child processes of the supervisor.  We don't do this
+% inside the supervisor itself, as there might be an exception.
+
+% (C) 2011 by Harald Welte <laforge@gnumonks.org>
+% (C) 2011 OnWaves
+%
+% All Rights Reserved
+%
+% This program is free software; you can redistribute it and/or modify
+% it under the terms of the GNU Affero General Public License as
+% published by the Free Software Foundation; either version 3 of the
+% License, or (at your option) any later version.
+%
+% This program is distributed in the hope that it will be useful,
+% but WITHOUT ANY WARRANTY; without even the implied warranty of
+% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+% GNU General Public License for more details.
+%
+% You should have received a copy of the GNU Affero General Public License
+% along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+-module(mgw_nat_adm).
+-author("Harald Welte <laforge@gnumonks.org>").
+
+-behaviour(gen_server).
+
+-export([init/1, handle_cast/2, handle_info/2, terminate/2, start_link/1]).
+-export([sccp_masq_reset/0, sccp_masq_dump/0, reload_config/0]).
+
+
+sccp_masq_reset() ->
+	gen_server:cast(?MODULE, sccp_masq_reset).
+
+sccp_masq_dump() ->
+	gen_server:cast(?MODULE, sccp_masq_dump).
+
+reload_config() ->
+	gen_server:cast(?MODULE, reload_all_config).
+
+
+start_link(Params) ->
+	gen_server:start_link({local, ?MODULE}, ?MODULE, Params, []).
+
+init(_Params) ->
+	{ok, foo}.
+
+handle_cast(sccp_masq_reset, LoopData) ->
+	sccp_masq:reset(),
+	{noreply, LoopData};
+
+handle_cast(sccp_masq_dump, LoopData) ->
+	sccp_masq:dump(),
+	{noreply, LoopData};
+
+handle_cast(reload_config, LoopData) ->
+	{noreply, LoopData};
+
+handle_cast(reload_all_config, LoopData) ->
+	map_masq:config_update(),
+	% now we iterate over the children and deliver the signal
+	Children = supervisor:which_children(mgw_nat_sup),
+	cast_to_children(Children, reload_config),
+	% and finally return to the main loop
+	{noreply, LoopData}.
+
+handle_info(Info, LoopData) ->
+	{noreply, LoopData}.
+
+terminate(_Reason, _LoopData) ->
+	ok.
+
+cast_to_children([], _Cast) ->
+	ok;
+cast_to_children([Child|Tail], Cast) ->
+	{Name, Pid, _Type, _Modules} = Child,
+	io:format("Casting ~p to ~p(~p)~n", [Cast, Name, Pid]),
+	gen_server:cast(Pid, Cast),
+	cast_to_children(Tail, Cast).

src/mgw_nat_app.erl

@@ -14,5 +14,4 @@ stop(_State) ->
 
 reload_config() ->
 	osmo_util:reload_config(),
-	mgw_nat_usr:reload_config(),
-	map_masq:config_update().
+	mgw_nat_adm:reload_config().

src/mgw_nat_sup.erl

@@ -27,7 +27,33 @@
 start_link() ->
 	supervisor:start_link({local, ?MODULE}, ?MODULE, []).
 
-init(Args) ->
-	MgwChild = {mgw_nat_usr, {mgw_nat_usr, start_link, [Args]},
+init(_Args) ->
+	sccp_masq:init(),
+	map_masq:config_update(),
+	SignLinkList = get_app_config(sign_links),
+	ChildList = gen_child_list(SignLinkList),
+	AdmChild = {mgw_nat_adm, {mgw_nat_adm, start_link, [foo]},
+		    permanent, 2000, worker, [mgw_nat_usr, sctp_handler,
+					      mgw_nat, mgw_nat_adm]},
+	{ok,{{one_for_one,60,600}, [AdmChild|ChildList]}}.
+
+% generate a list of child specifications, one for each signalling link
+gen_child_list(SignLinkList) ->
+	gen_child_list(SignLinkList, []).
+gen_child_list([], ChildList) ->
+	ChildList;
+gen_child_list([Link|Tail], ChildList) ->
+	{Name, ChildArgs} = Link,
+	NewChild = {Name, {mgw_nat_usr, start_link, [[{msc_name, Name}|ChildArgs]]},
 		    permanent, 2000, worker, [mgw_nat_usr, sctp_handler, mgw_nat]},
-	{ok,{{one_for_all,60,600}, [MgwChild]}}.
+	gen_child_list(Tail, [NewChild|ChildList]).
+
+get_app_config(Name) ->
+	case application:get_env(Name) of
+	    undefined ->
+		error_logger:error_report([{error, app_cfg_missing},
+					   {get_app_config, Name}]),
+		throw(app_cfg_missing);
+	    {ok, Val} ->
+		Val
+	end.

src/mgw_nat_usr.erl

@@ -23,74 +23,57 @@
 
 -behavior(gen_server).
 
--export([start_link/1, stop/0, sccp_masq_reset/0, sccp_masq_dump/0,
-	 reload_config/0]).
+-export([start_link/1, stop/0]).
 -export([init/1, handle_cast/2, handle_info/2, terminate/2]).
 
 
 start_link(Params) ->
-	gen_server:start_link({local, ?MODULE}, ?MODULE, Params, []).
+	MscName = get_cfg_pl_val(msc_name, Params),
+	gen_server:start_link({local, MscName}, ?MODULE, Params, []).
 
 stop() ->
 	gen_server:cast(?MODULE, stop).
 
-sccp_masq_reset() ->
-	gen_server:cast(?MODULE, sccp_masq_reset).
-
-sccp_masq_dump() ->
-	gen_server:cast(?MODULE, sccp_masq_dump).
-
-reload_config() ->
-	gen_server:cast(?MODULE, reload_config).
-
 %% Callback functions of the OTP behavior
 
-init(_Params) ->
-	sccp_masq:init(),
-	map_masq:config_update(),
-	MscLocalIp = get_app_config(msc_local_ip),
-	MscLocalPort = get_app_config(msc_local_port),
-	MscRemoteIp = get_app_config(msc_remote_ip),
-	StpRemoteIp = get_app_config(stp_remote_ip),
-	StpRemotePort = get_app_config(stp_remote_port),
-	RewriteActMod = get_app_config(rewrite_act_mod),
+init(Params) ->
+	io:format("Starting mgw_nat_usr with Args ~p~n", [Params]),
+	MscLocalIp = get_cfg_pl_val(msc_local_ip, Params),
+	MscLocalPort = get_cfg_pl_val(msc_local_port, Params),
+	MscRemoteIp = get_cfg_pl_val(msc_remote_ip, Params),
+	StpRemoteIp = get_cfg_pl_val(stp_remote_ip, Params),
+	StpRemotePort = get_cfg_pl_val(stp_remote_port, Params),
+	RewriteActMod = get_cfg_pl_val(rewrite_act_mod, Params),
 	RewriteActMod:reload_config(),
-	io:format("Starting mgw_nat_usr with rewrite actor module ~p~n", [RewriteActMod]),
 	SctpHdlrArgs =	[MscLocalIp, MscLocalPort, MscRemoteIp,
 			 StpRemoteIp, StpRemotePort, RewriteActMod],
-	apply(sctp_handler, init, SctpHdlrArgs).
+	LoopDat = apply(sctp_handler, init, SctpHdlrArgs),
+	{ok, {Params, LoopDat}}.
+
+% this cast is produced by mgw_nat_sup child walker
+handle_cast(reload_config, L = {Params, _LoopData}) ->
+	RewriteActMod = get_cfg_pl_val(rewrite_act_mod, Params),
+	RewriteActMod:reload_config(),
+	{noreply, L};
 
 handle_cast(stop, LoopData) ->
-	{stop, normal, LoopData};
-
-handle_cast(sccp_masq_reset, LoopData) ->
-	sccp_masq:reset(),
-	{noreply, LoopData};
-
-handle_cast(sccp_masq_dump, LoopData) ->
-	sccp_masq:dump(),
-	{noreply, LoopData};
-
-handle_cast(reload_config, LoopData) ->
-	RewriteActMod = get_app_config(rewrite_act_mod),
-	RewriteActMod:reload_config(),
-	{noreply, LoopData}.
+	{stop, normal, LoopData}.
 
 
 terminate(_Reason, _LoopData) ->
 	ok.
 
 % callback for other events like incoming SCTP message
-handle_info({sctp, Sock, Ip, Port, Data}, LoopData) ->
+handle_info({sctp, Sock, Ip, Port, Data}, {InitParams, LoopData}) ->
 	NewL = sctp_handler:handle_sctp(LoopData, {sctp, Sock, Ip, Port, Data}),
-	{noreply, NewL}.
+	{noreply, {InitParams, NewL}}.
 
-get_app_config(Name) ->
-	case application:get_env(Name) of
+% wrapper around proplists:get_value() to check for missing stuff
+get_cfg_pl_val(Name, List) ->
+	case proplists:get_value(Name, List) of
 	    undefined ->
 		error_logger:error_report([{error, app_cfg_missing},
-					   {get_app_config, Name}]),
-		throw(app_cfg_missing);
-	    {ok, Val} ->
+					   {get_cfg_pl_val, Name}]);
+	    Val ->
 		Val
 	end.