Make MGW nat more flexible by introdicng actors an function references

Instead of a static configuration of rewrite/mangling/patching steps,
we now introduce the concept of a 'rewrite_actor', which is a callback
function that determines which rewrite/patching code to call at which
particular layer of the protocol.

The default rewrite actor "bow_onw" resembles the existing rewrite
behavior.

There is a stub new rewrite actore "vfuk_onw", which will be used
for Camel phase rewriting.

1 files changed, 14 insertions, 24 deletions

diff --git a/src/sctp_handler.erl b/src/sctp_handler.erl
index 333d551..3011cfa 100644
--- a/src/sctp_handler.erl
+++ b/src/sctp_handler.erl
@@ -22,7 +22,7 @@
 
 -module(sctp_handler).
 -author("Harald Welte <laforge@gnumonks.org>").
--export([init/5, handle_sctp/2]).
+-export([init/6, handle_sctp/2]).
 
 -include_lib("kernel/include/inet.hrl").
 -include_lib("kernel/include/inet_sctp.hrl").
@@ -35,13 +35,14 @@
 -record(loop_data,
 	{msc_sock, msc_local_ip, msc_remote_ip, msc_remote_port,
 	 msc_local_port, msc_assoc_id, 
-	 stp_sock, stp_remote_ip, stp_remote_port, stp_assoc_id
+	 stp_sock, stp_remote_ip, stp_remote_port, stp_assoc_id,
+	 handle_fn
 	}).
 
 -define(COMMON_SOCKOPTS, [{active, once}, {reuseaddr, true}]).
 
 % initialize the sockets towards MSC (listening) and STP (connect)
-init(MscLocalIP, MscLocalPort, MscRemoteIP, StpRemoteIP, StpRemotePort) ->
+init(MscLocalIP, MscLocalPort, MscRemoteIP, StpRemoteIP, StpRemotePort, HandleFn) ->
 	{ok, MscSock} = gen_sctp:open([{ip, MscLocalIP},{port,MscLocalPort}]
 					++ ?COMMON_SOCKOPTS),
 	io:format("Listening for MSC on ~w:~w. ~w~n",
@@ -51,7 +52,7 @@ init(MscLocalIP, MscLocalPort, MscRemoteIP, StpRemoteIP, StpRemotePort) ->
 	L = #loop_data{msc_sock = MscSock, msc_local_ip = MscLocalIP, 
 			msc_remote_ip = MscRemoteIP,
 			stp_sock = StpSock, stp_remote_ip = StpRemoteIP,
-			stp_remote_port = StpRemotePort},
+			stp_remote_port = StpRemotePort, handle_fn = HandleFn},
 	{ok, L}.
 
 % initiate a connection to STP as a client
@@ -61,7 +62,8 @@ initiate_stp_connection(#loop_data{stp_sock = Sock, stp_remote_ip = IP, stp_remo
 
 % main loop function
 handle_sctp(L = #loop_data{msc_sock=MscSock, msc_remote_ip=MscRemoteIp, msc_remote_port=MscRemotePort,
-		    stp_sock=StpSock, stp_remote_ip=StpRemoteIp, stp_remote_port=StpRemotePort},
+		    stp_sock=StpSock, stp_remote_ip=StpRemoteIp, stp_remote_port=StpRemotePort,
+		    handle_fn=HandleFn},
 	    Sctp) ->
 	io:format("Entering receive loop ~p~n", [L]),
 	io:format("======================================================================~n"),
@@ -102,13 +104,13 @@ handle_sctp(L = #loop_data{msc_sock=MscSock, msc_remote_ip=MscRemoteIp, msc_remo
 		% MSC data
 		{sctp, MscSock, MscRemoteIp, MscRemotePort, {[Anc], Data}} ->
 			io:format("MSC rx data: ~p ~p~n", [Anc, Data]),
-			handle_rx_data(L, from_msc, Anc, Data),
+			handle_rx_data(HandleFn, L, from_msc, Anc, Data),
 			inet:setopts(MscSock, [{active, once}]),
 			NewL = L;
 		% STP data
 		{sctp, StpSock, StpRemoteIp, StpRemotePort, {[Anc], Data}} ->
 			io:format("STP rx data: ~p ~p~n", [Anc, Data]),
-			handle_rx_data(L, from_stp, Anc, Data),
+			handle_rx_data(HandleFn, L, from_stp, Anc, Data),
 			inet:setopts(StpSock, [{active, once}]),
 			NewL = L;
 		{sctp, _Sock, RemoteIp, _Remote_port, {_Anc, Data}}
@@ -124,23 +126,10 @@ handle_sctp(L = #loop_data{msc_sock=MscSock, msc_remote_ip=MscRemoteIp, msc_remo
 	NewL.
 
 
-try_mangle(L, From, Data) ->
-	try mgw_nat:mangle_rx_data(L, From, Data) of
-		Val ->
-			Val
-		catch error:Error ->
-			% some parser error, simply forward msg unmodified
-			io:format("MGW NAT mangling Error: ~p~n", [Error]),
-			Data
-		end.
-
 % handle incoming data on one of the SCTP sockets
-handle_rx_data(_L, From, SRInfo, Data) when is_binary(Data) ->
-	io:format("Unhandled Rx Data from SCTP from ~p: ~p, ~p~n", [From, SRInfo, Data]);
-
-handle_rx_data(L, From, SRInf = #sctp_sndrcvinfo{ppid = 2, 
+handle_rx_data(Fn, L, From, SRInf = #sctp_sndrcvinfo{ppid = 2,
 						 stream = Stream}, Data) when is_binary(Data) ->
-	DataOut = try_mangle(L, From, Data),
+	DataOut = Fn(sctp, From, [L, SRInf], 2, Data),
 	% send mangled data to other peer
 	case From of
 		from_msc ->
@@ -158,6 +147,7 @@ handle_rx_data(L, From, SRInf = #sctp_sndrcvinfo{ppid = 2,
 	   true ->
 		io:format("Data is NOT equal~n")
 	end,
-	ok = gen_sctp:send(Sock, SndRcvInfo, DataOut).
-
+	ok = gen_sctp:send(Sock, SndRcvInfo, DataOut);
 
+handle_rx_data(_Fn, _L, From, SRInfo, Data) when is_binary(Data) ->
+	io:format("Unhandled Rx Data from SCTP from ~p: ~p, ~p~n", [From, SRInfo, Data]).