| % SCTP Handler for gateway between MSC and STP, transparently |
| % rewriting addresses on the fly |
| |
| % (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(sctp_handler). |
| -author("Harald Welte <laforge@gnumonks.org>"). |
| -export([init/5, handle_sctp/2]). |
| |
| -include_lib("kernel/include/inet.hrl"). |
| -include_lib("kernel/include/inet_sctp.hrl"). |
| |
| %-include("m2ua.hrl"). |
| %-include("mtp3.hrl"). |
| %-include("isup.hrl"). |
| %-include("sccp.hrl"). |
| |
| -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 |
| }). |
| |
| -define(COMMON_SOCKOPTS, [{active, once}, {reuseaddr, true}]). |
| |
| % initialize the sockets towards MSC (listening) and STP (connect) |
| init(MscLocalIP, MscLocalPort, MscRemoteIP, StpRemoteIP, StpRemotePort) -> |
| {ok, MscSock} = gen_sctp:open([{ip, MscLocalIP},{port,MscLocalPort}] |
| ++ ?COMMON_SOCKOPTS), |
| io:format("Listening for MSC on ~w:~w. ~w~n", |
| [MscLocalIP, MscLocalPort, MscSock]), |
| ok = gen_sctp:listen(MscSock, true), |
| {ok, StpSock} = gen_sctp:open(?COMMON_SOCKOPTS), |
| 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}, |
| {ok, L}. |
| |
| % initiate a connection to STP as a client |
| initiate_stp_connection(#loop_data{stp_sock = Sock, stp_remote_ip = IP, stp_remote_port = Port}, Opts) -> |
| io:format("Establishing SCTP conn to STP ~p Port ~p~n", [IP, Port]), |
| gen_sctp:connect(Sock, IP, Port, Opts ++ ?COMMON_SOCKOPTS). |
| |
| % 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}, |
| Sctp) -> |
| io:format("Entering receive loop ~p~n", [L]), |
| io:format("======================================================================~n"), |
| case Sctp of |
| % MSC connect or disconnect |
| {sctp, MscSock, MscRemoteIp, Port, {ANC, SAC}} |
| when is_record(SAC, sctp_assoc_change) -> |
| io:format("MSC sctp_assoc_change ~p ~p~n", [ANC, SAC]), |
| #sctp_assoc_change{state = SacState, outbound_streams = OutStreams, |
| inbound_streams = InStreams, assoc_id = MscAssocId} = SAC, |
| case SacState of |
| comm_up -> |
| InitMsg = #sctp_initmsg{num_ostreams=InStreams, |
| max_instreams=OutStreams}, |
| {ok, StpAssoc} = initiate_stp_connection(L, [{sctp_initmsg,InitMsg}]), |
| io:format("STP Assoc: ~p~n", [StpAssoc]), |
| NewL = L#loop_data{msc_remote_port = Port, |
| msc_assoc_id = MscAssocId, |
| stp_assoc_id = StpAssoc#sctp_assoc_change.assoc_id}; |
| comm_lost -> |
| NewL = L, |
| % maybe we should simply die? |
| io:format("MSC SCTP comm_lost~n"), |
| exit(1); |
| addr_unreachable -> |
| NewL = L, |
| io:format("MSC SCTP addr_unreachable~n"), |
| % maybe we should simply die? |
| exit(1) |
| end, |
| inet:setopts(MscSock, [{active, once}]); |
| % STP connect or disconnect |
| {sctp, StpSock, StpRemoteIp, StpRemotePort, {_Anc, SAC}} |
| when is_record(SAC, sctp_assoc_change) -> |
| io:format("STP sctp_assoc_change ~p~n", [SAC]), |
| inet:setopts(StpSock, [{active, once}]), |
| NewL = L; |
| % 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), |
| 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), |
| inet:setopts(StpSock, [{active, once}]), |
| NewL = L; |
| {sctp, _Sock, RemoteIp, _Remote_port, {_Anc, Data}} |
| when is_record(Data, sctp_shutdown_event) -> |
| % maybe we should simply die? |
| NewL = L, |
| io:format("SCTP remote ~p shutdown~n", [RemoteIp]), |
| exit(1); |
| Other -> |
| io:format("OTHER ~p~n", [Other]), |
| NewL = L |
| end, |
| 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, SRInf = #sctp_sndrcvinfo{ppid = 2, |
| stream = Stream}, Data) when is_binary(Data) -> |
| DataOut = try_mangle(L, From, Data), |
| % send mangled data to other peer |
| case From of |
| from_msc -> |
| Sock = L#loop_data.stp_sock, |
| AssocId = L#loop_data.stp_assoc_id; |
| from_stp -> |
| Sock = L#loop_data.msc_sock, |
| AssocId = L#loop_data.msc_assoc_id |
| end, |
| SndRcvInfo = #sctp_sndrcvinfo{ppid = 2, stream = Stream, assoc_id = AssocId}, |
| %io:format("Sending ~p to ~p ~p~n", [DataOut, Sock, SndRcvInfo]), |
| % if they are not equal, we will abort here |
| if DataOut == Data -> |
| ok; |
| true -> |
| io:format("Data is NOT equal~n") |
| end, |
| ok = gen_sctp:send(Sock, SndRcvInfo, DataOut). |
| |
| |