add dummy ss7 service dumper module

Instead of implementing a real subsystem, it just dumps all MTP3 payload
messages of specified service
diff --git a/ebin/osmo_ss7.app b/ebin/osmo_ss7.app
index 20f143f..f3d5f05 100644
--- a/ebin/osmo_ss7.app
+++ b/ebin/osmo_ss7.app
@@ -11,6 +11,7 @@
 			sccp_codec,
 			osmo_ss7_sup, osmo_ss7_app,
 			ss7_links, ss7_link_m3ua, ss7_link_ipa_client,
+			ss7_service_dump,
 			osmo_ss7_gtt,
 			osmo_ss7_pcap
 		]},
diff --git a/src/ss7_service_dump.erl b/src/ss7_service_dump.erl
new file mode 100644
index 0000000..f28869d
--- /dev/null
+++ b/src/ss7_service_dump.erl
@@ -0,0 +1,64 @@
+% SS7 service handler for dumping MTP3 payload (testing)
+
+% (C) 2010-2011 by Harald Welte <laforge@gnumonks.org>
+%
+% 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(ss7_service_dump).
+-behaviour(gen_fsm).
+-export([start_link/1, init/1, idle/2]).
+
+-include_lib("osmo_ss7/include/osmo_util.hrl").
+-include_lib("osmo_ss7/include/mtp3.hrl").
+-include_lib("osmo_ss7/include/isup.hrl").
+-include_lib("osmo_ss7/include/sccp.hrl").
+
+-record(loop_dat, {
+	ssns
+}).
+
+start_link(Ssns) ->
+	gen_fsm:start_link(ss7_service_dump, [Ssns], []).
+
+init(Ssn) when is_integer(Ssn) ->
+	init([Ssn]);
+init(Ssns) when is_list(Ssns) ->
+	bind_services(Ssns),
+	{ok, idle, #loop_dat{ssns = Ssns}}.
+
+bind_services([]) ->
+	ok;
+bind_services([Head|Tail]) ->
+	ok = ss7_links:bind_service(Head, "ss7_service_dump"),
+	bind_services(Tail).
+
+parse_mtp3(#mtp3_msg{service_ind = ?MTP3_SERV_SCCP, payload = Payload}) ->
+	sccp_codec:parse_sccp_msg(Payload);
+parse_mtp3(#mtp3_msg{service_ind = ?MTP3_SERV_ISUP, payload = Payload}) ->
+	isup_codec:parse_isup_msg(Payload).
+
+idle(#primitive{subsystem = 'MTP', gen_name = 'TRANSFER',
+		spec_name = indication, parameters = Mtp3Msg}, LoopDat) ->
+	io:format("ss7_service_dump in: ~p~n", [Mtp3Msg]),
+	try parse_mtp3(Mtp3Msg) of
+		Parsed ->
+			io:format("ss7_service_dump out: ~p~n", [Parsed])
+	catch
+		_ ->
+			io:format("ss7_service_dump parser error~n")
+	end,
+	{next_state, idle, LoopDat}.