[megaco|test] Update load suite to use inet-backend option

OTP-17533

3 files changed, 231 insertions, 118 deletions

diff --git a/lib/megaco/test/megaco_load_SUITE.erl b/lib/megaco/test/megaco_load_SUITE.erl
index d033e137ec..4032d86186 100644
--- a/lib/megaco/test/megaco_load_SUITE.erl
+++ b/lib/megaco/test/megaco_load_SUITE.erl
@@ -62,7 +62,7 @@
 
 -define(MGC_START(Node, Mid, ET, Conf, Verb), 
         megaco_test_mgc:start(Node, Mid, ET, 
-			      [{megaco_trace, false}] ++ Conf, Verb)).
+			      Conf ++ [{megaco_trace, false}], Verb)).
 -define(MGC_STOP(Pid), megaco_test_mgc:stop(Pid)).
 -define(MGC_USER_INFO(Pid,Tag), megaco_test_mgc:user_info(Pid,Tag)).
 -define(MGC_CONN_INFO(Pid,Tag), megaco_test_mgc:conn_info(Pid,Tag)).
@@ -70,8 +70,8 @@
 
 -define(MG_START(Pid, Mid, Enc, Transp, Conf, Verb), 
         megaco_test_mg:start(Pid, Mid, Enc, Transp, 
-			     [{megaco_trace, false},
-			      {transport_opts, [{serialize, true}]}] ++ Conf, 
+			     Conf ++ [{megaco_trace, false},
+                                      {transport_opts, [{serialize, true}]}], 
 			     Verb)).
 -define(MG_STOP(Pid), megaco_test_mg:stop(Pid)).
 -define(MG_USER_INFO(Pid,Tag), megaco_test_mg:user_info(Pid,Tag)).
@@ -92,15 +92,47 @@ suite() ->
     [{ct_hooks, [ts_install_cth]}].
 
 all() -> 
+    %% This is a temporary messure to ensure that we can 
+    %% test the socket backend without effecting *all*
+    %% applications on *all* machines.
+    %% This flag is set only for *one* host.
+    case ?TEST_INET_BACKENDS() of
+        true ->
+            [
+             {group, inet_backend_default},
+             {group, inet_backend_inet},
+             {group, inet_backend_socket}
+            ];
+        _ ->
+            [
+             {group, inet_backend_default}
+            ]
+    end.
+
+groups() -> 
     [
-     {group, single},
-     {group, multi}
+     {inet_backend_default, [], inet_backend_default_cases()},
+     {inet_backend_inet,    [], inet_backend_inet_cases()},
+     {inet_backend_socket,  [], inet_backend_socket_cases()},
+
+     {all,                  [], all_cases()},
+     {single,               [], single_cases()},
+     {multi,                [], multi_cases()}
     ].
 
-groups() -> 
+inet_backend_default_cases() ->
+    [{all, [], all_cases()}].
+
+inet_backend_inet_cases() ->
+    [{all, [], all_cases()}].
+
+inet_backend_socket_cases() ->
+    [{all, [], all_cases()}].
+
+all_cases() -> 
     [
-     {single, [], single_cases()},
-     {multi,  [], multi_cases()}
+     {group, single},
+     {group, multi}
     ].
 
 single_cases() ->
@@ -174,10 +206,39 @@ end_per_suite(Config0) when is_list(Config0) ->
 %% -----
 %%
 
-init_per_group(_GroupName, Config) ->
+init_per_group(inet_backend_default = Group, Config) ->
+    ?ANNOUNCE_GROUP_INIT(Group),
+    [{socket_create_opts, []} | Config];
+init_per_group(inet_backend_inet = Group, Config) ->
+    ?ANNOUNCE_GROUP_INIT(Group),
+    case ?EXPLICIT_INET_BACKEND() of
+        true ->
+            %% The environment trumps us,
+            %% so only the default group should be run!
+            {skip, "explicit inet backend"};
+        false ->
+            [{socket_create_opts, [{inet_backend, inet}]} | Config]
+    end;
+init_per_group(inet_backend_socket = Group, Config) ->
+    ?ANNOUNCE_GROUP_INIT(Group),
+    case ?EXPLICIT_INET_BACKEND() of
+        true ->
+            %% The environment trumps us,
+            %% so only the default group should be run!
+            {skip, "explicit inet backend"};
+        false ->
+            [{socket_create_opts, [{inet_backend, socket}]} | Config]
+    end;
+init_per_group(Group, Config) ->
+    ?ANNOUNCE_GROUP_INIT(Group),
     Config.
 
-end_per_group(_GroupName, Config) ->
+end_per_group(Group, Config) when (inet_backend_default =:= Group) orelse
+                                  (inet_backend_init    =:= Group) orelse
+                                  (inet_backend_socket  =:= Group) ->
+    ?SLEEP(?SECS(5)),
+    Config;
+end_per_group(_Group, Config) ->
     Config.
 
 
@@ -397,25 +458,28 @@ try_single_user_load(Name, Config, NumLoaders0) ->
 
 single_user_load(State, Config, NumLoaders) ->
     i("starting with ~w loader(s)", [NumLoaders]),
+    SCO = ?config(socket_create_opts, Config),
     Res = load_controller(Config, 
 			  fun(Env) -> 
 				  populate(Env), 
-				  exit( single_user_load(State, NumLoaders) ) 
+				  exit( do_single_user_load(SCO,
+                                                            State, NumLoaders) ) 
 			  end),
     i("done"),
     Res.
 
-single_user_load([MgcNode, MgNode], NumLoaders) ->
+do_single_user_load(SCO,
+                    [MgcNode, MgNode], NumLoaders) ->
     %% Start the MGC and MGs
     i("[MGC] start"),
     MgcMid = {deviceName, "ctrl"},
     ET     = [{text, tcp, [{serialize, true}]}],
     DSI = maybe_display_system_info(NumLoaders),
-    {ok, Mgc} = ?MGC_START(MgcNode, MgcMid, ET, DSI, ?MGC_VERBOSITY),
+    {ok, Mgc} = ?MGC_START(MgcNode, MgcMid, ET, SCO ++ DSI, ?MGC_VERBOSITY),
 
     i("[MG] start"),
     MgMid = {deviceName, "mg"},
-    {ok, Mg} = ?MG_START(MgNode, MgMid, text, tcp, DSI, ?MG_VERBOSITY),
+    {ok, Mg} = ?MG_START(MgNode, MgMid, text, tcp, SCO ++ DSI, ?MG_VERBOSITY),
 
     d("MG user info: ~p", [?MG_USER_INFO(Mg, all)]),
 
@@ -501,17 +565,18 @@ try_multi_user_load(Name, Config, NumUsers, NumLoaders0) ->
 
 multi_user_load(State, Config, NumUsers, NumLoaders) ->
     i("starting with ~w loader(s)", [NumLoaders]),
+    SCO = ?config(socket_create_opts, Config),
     Res = load_controller(
 	    Config, 
 	    fun(Env) -> 
 		    populate(Env), 
-		    exit( multi_user_load(State, NumUsers, NumLoaders) ) 
+		    exit( do_multi_user_load(SCO, State, NumUsers, NumLoaders) ) 
 	    end),
     i("done"),
     Res.
 
 
-multi_user_load([MgcNode | MgNodes], NumUsers, NumLoaders) 
+do_multi_user_load(SCO, [MgcNode | MgNodes], NumUsers, NumLoaders) 
   when (is_integer(NumUsers) andalso (NumUsers > 1) andalso 
 	is_integer(NumLoaders) andalso (NumLoaders >= 1)) ->
     %% Start the MGC and MGs
@@ -519,7 +584,7 @@ multi_user_load([MgcNode | MgNodes], NumUsers, NumLoaders)
     MgcMid = {deviceName, "ctrl"},
     ET     = [{text, tcp, [{serialize, false}]}],
     DSI = maybe_display_system_info(2 * NumUsers * NumLoaders),
-    {ok, Mgc} = ?MGC_START(MgcNode, MgcMid, ET, DSI, ?MGC_VERBOSITY),
+    {ok, Mgc} = ?MGC_START(MgcNode, MgcMid, ET, SCO ++ DSI, ?MGC_VERBOSITY),
 
     megaco_test_mgc:update_user_info(Mgc,reply_timer,1000),
     d("MGC user info: ~p", [?MGC_USER_INFO(Mgc, all)]),
@@ -527,7 +592,7 @@ multi_user_load([MgcNode | MgNodes], NumUsers, NumLoaders)
     MgUsers = make_mids(MgNodes),
 
     d("start MGs, apply the load and stop MGs"),
-    ok = multi_load(MgUsers, DSI, NumLoaders, ?MULTI_USER_LOAD_NUM_REQUESTS),
+    ok = multi_load(MgUsers, SCO ++ DSI, NumLoaders, ?MULTI_USER_LOAD_NUM_REQUESTS),
 
     i("flush the message queue: ~p", [megaco_test_lib:flush()]),
 
@@ -542,14 +607,14 @@ multi_user_load([MgcNode | MgNodes], NumUsers, NumLoaders)
     ok.
 
 
-multi_load(MGs, DSI, NumLoaders, NumReqs) ->
+multi_load(MGs, Conf, NumLoaders, NumReqs) ->
     d("multi_load -> entry with"
       "~n   MGs:        ~p"
-      "~n   DSI:        ~p"
+      "~n   Conf:       ~p"
       "~n   NumLoaders: ~p"
-      "~n   NumReqs:    ~p", [MGs, DSI, NumLoaders, NumReqs]),
+      "~n   NumReqs:    ~p", [MGs, Conf, NumLoaders, NumReqs]),
 
-    Pids = multi_load_collector_start(MGs, DSI, NumLoaders, NumReqs, []),
+    Pids = multi_load_collector_start(MGs, Conf, NumLoaders, NumReqs, []),
     case timer:tc(?MODULE, do_multi_load, [Pids, NumLoaders, NumReqs]) of
 	{Time, {ok, OKs, []}} ->
 	    Sec = Time / 1000000,
@@ -569,13 +634,13 @@ do_multi_load(Pids, _NumLoaders, _NumReqs) ->
     lists:foreach(Fun, Pids),
     await_multi_load_collectors(Pids, [], []).
 
-multi_load_collector_start([], _DSI, _NumLoaders, _NumReqs, Pids) ->
+multi_load_collector_start([], _Conf, _NumLoaders, _NumReqs, Pids) ->
     Pids;
-multi_load_collector_start([{Mid, Node}|MGs], DSI, NumLoaders, NumReqs, Pids) ->
+multi_load_collector_start([{Mid, Node}|MGs], Conf, NumLoaders, NumReqs, Pids) ->
     Env = get(),
     Pid = spawn_link(?MODULE, multi_load_collector, 
-		     [self(), Node, Mid, DSI, NumLoaders, NumReqs, Env]),
-    multi_load_collector_start(MGs, DSI, NumLoaders, NumReqs, [{Pid,Mid}|Pids]).
+		     [self(), Node, Mid, Conf, NumLoaders, NumReqs, Env]),
+    multi_load_collector_start(MGs, Conf, NumLoaders, NumReqs, [{Pid,Mid}|Pids]).
 
 get_env(Key, Env) ->
     case lists:keysearch(Key, 1, Env) of
@@ -585,13 +650,13 @@ get_env(Key, Env) ->
 	    undefined
     end.
 
-multi_load_collector(Parent, Node, Mid, DSI, NumLoaders, NumReqs, Env) ->
+multi_load_collector(Parent, Node, Mid, Conf, NumLoaders, NumReqs, Env) ->
     put(verbosity, get_env(verbosity, Env)),
     put(tc, get_env(tc, Env)),
     put(sname, get_env(sname, Env) ++ "-loader"),
-    case ?MG_START(Node, Mid, text, tcp, DSI, ?MG_VERBOSITY) of
+    case ?MG_START(Node, Mid, text, tcp, Conf, ?MG_VERBOSITY) of
 	{ok, Pid} ->
-	    d("MG ~p user info: ~n~p", [Mid, ?MG_USER_INFO(Pid,all)]),
+	    d("MG ~p user info: ~n~p", [Mid, ?MG_USER_INFO(Pid, all)]),
 	    ServChRes = ?MG_SERV_CHANGE(Pid),
 	    d("service change result: ~p", [ServChRes]),
 	    megaco_test_mg:update_conn_info(Pid,reply_timer,1000),
diff --git a/lib/megaco/test/megaco_test_mg.erl b/lib/megaco/test/megaco_test_mg.erl
index e84adc7de6..9d096430db 100644
--- a/lib/megaco/test/megaco_test_mg.erl
+++ b/lib/megaco/test/megaco_test_mg.erl
@@ -67,7 +67,9 @@
 -define(A5555, tid(255*256*256 + 255*256)       ).
 -define(A5556, tid(255*256*256 + 255*256 + 255) ).
 
--record(mg, {mid             = undefined,
+-record(mg, {parent          = undefined,
+             inet_backend    = default,
+	     mid             = undefined,
 	     state           = initiated,
 	     req_handler     = undefined,
 	     call_mode       = async,
@@ -78,7 +80,6 @@
 	     load_counter    = 0,
 	     reply_counter   = 0,
 	     mload_info      = undefined,
-	     parent          = undefined,
 	     dsi_timer,
              evs             = []}).
 
@@ -354,11 +355,16 @@ mg(Parent, Verbosity, Config) ->
     case (catch init(Config)) of
 	{error, _} = Error ->
 	    exit(Error);
+
 	{'EXIT', Reason} ->
 	    exit({init_failed, Reason});
-	{ok, Mid, DSITimer} ->
+
+	{ok, IB, Mid, DSITimer} ->
 	    notify_started(Parent),
-	    MG = #mg{parent = Parent, mid = Mid, dsi_timer = DSITimer},
+	    MG = #mg{parent       = Parent,
+                     inet_backend = IB,
+                     mid          = Mid,
+                     dsi_timer    = DSITimer},
 	    i("mg -> started"),
 	    put(verbosity, Verbosity),
 	    case (catch loop(evs(MG, started))) of
@@ -380,12 +386,16 @@ init(Config) ->
       "~n      Config: ~p", [Config]),
     random_init(),
     d("init -> random initiated"),
-    Mid = get_conf(local_mid, Config),
-    d("init -> Mid: ~p", [Mid]),
+
+    IB  = get_conf(inet_backend, Config, default),
+    Mid = get_conf(local_mid,    Config),
     RI  = get_conf(receive_info, Config),
-    d("init -> RI: ~p", [RI]),
 
-    d("init -> maybe start the display system info timer"),
+    d("init -> "
+      "~n      Inet Backend: ~p"
+      "~n      Mid:          ~p"
+      "~n      RI:           ~p", [IB, Mid, RI]),
+
     DSITimer = 
 	case get_conf(display_system_info, Config, undefined) of
 	    Time when is_integer(Time) ->
@@ -395,6 +405,7 @@ init(Config) ->
 		undefined
 	end,
     Conf0 = lists:keydelete(display_system_info, 1, Config),
+    Conf1 = lists:keydelete(inet_backend,        1, Conf0),
 
     d("init -> start megaco"),
     application:start(megaco),
@@ -411,12 +422,12 @@ init(Config) ->
 	_ ->
 	    ok
     end,
-    Conf1 = lists:keydelete(megaco_trace, 1, Conf0),
+    Conf2 = lists:keydelete(megaco_trace, 1, Conf1),
     
     d("init -> start megaco user"),
-    Conf2 = lists:keydelete(local_mid,    1, Conf1),
-    Conf3 = lists:keydelete(receive_info, 1, Conf2),
-    ok = megaco:start_user(Mid, Conf3),
+    Conf3 = lists:keydelete(local_mid,    1, Conf2),
+    Conf4 = lists:keydelete(receive_info, 1, Conf3),
+    ok = megaco:start_user(Mid, Conf4),
     d("init -> update user info (user_mod)"),
     ok = megaco:update_user_info(Mid, user_mod,  ?MODULE),
     d("init -> update user info (user_args)"),
@@ -427,8 +438,8 @@ init(Config) ->
     d("init -> parse receive info"),
     {MgcPort, MgcHost, RH1, TO} = parse_receive_info(RI, RH),
     d("init -> start transport (with ~p)", [TO]),
-    {ok, _CH} = start_transport(MgcPort, MgcHost, RH1, TO),
-    {ok, Mid, DSITimer}.
+    {ok, _CH} = start_transport(IB, MgcPort, MgcHost, RH1, TO),
+    {ok, IB, Mid, DSITimer}.
 
 
 loop(#mg{parent = Parent, mid = Mid} = S) ->
@@ -936,39 +947,43 @@ parse_receive_info(RI, RH) ->
     {TP, TH, RH1, TO}.
 
 
-start_transport(MgcPort, MgcHost, 
-		   #megaco_receive_handle{send_mod = megaco_tcp} = RH, TO) ->
-    start_tcp(MgcPort, MgcHost, RH, TO);
-start_transport(MgcPort, MgcHost, 
-		   #megaco_receive_handle{send_mod = megaco_udp} = RH, TO) ->
-    start_udp(MgcPort, MgcHost, RH, TO);
-start_transport(_, _, #megaco_receive_handle{send_mod = Mod}, _TO) ->
+start_transport(IB,
+                MgcPort, MgcHost, 
+                #megaco_receive_handle{send_mod = megaco_tcp} = RH, TO) ->
+    start_tcp(IB, RH, TO, MgcPort, MgcHost);
+start_transport(IB,
+                MgcPort, MgcHost, 
+                #megaco_receive_handle{send_mod = megaco_udp} = RH, TO) ->
+    start_udp(IB, RH, TO, MgcPort, MgcHost);
+start_transport(_, _, _, #megaco_receive_handle{send_mod = Mod}, _TO) ->
     throw({error, {bad_send_mod, Mod}}).
 
 
-start_tcp(MgcPort, MgcHost, RH, TO) ->
+start_tcp(IB, RH, TO, MgcPort, MgcHost) ->
     d("start tcp transport: "
+      "~n      Inet Backend:      ~p"
       "~n      MGC Port:          ~p"
       "~n      MGC Host:          ~p"
       "~n      Receive handle:    ~p"
-      "~n      Transport options: ~p", [MgcPort, MgcHost, RH, TO]),
+      "~n      Transport options: ~p", [IB, MgcPort, MgcHost, RH, TO]),
     case megaco_tcp:start_transport() of
 	{ok, Sup} ->
 	    d("tcp transport started: ~p", [Sup]),
-	    start_tcp_connect(TO, RH, MgcPort, MgcHost, Sup);
+	    start_tcp_connect(IB, TO, RH, MgcPort, MgcHost, Sup);
         {error, Reason} ->
             throw({error, {megaco_tcp_start_transport, Reason}})
     end.
 
-start_tcp_connect(TO, RH, Port, Host, Sup) ->
+start_tcp_connect(IB, TO, RH, Port, Host, Sup) ->
     d("try tcp connecting to: ~p:~p", [Host, Port]),
-    Opts = [{host,           Host},
+    Opts = [{inet_backend,   IB},
+            {host,           Host},
 	    {port,           Port}, 
 	    {receive_handle, RH},
 	    {tcp_options,    [{nodelay, true}]}] ++ TO,
-    try_start_tcp_connect(RH, Sup, Opts, 250, noError).
+    try_start_tcp_connect(RH, Opts, Sup, 250, noError).
 
-try_start_tcp_connect(RH, Sup, Opts, Timeout, Error0) when (Timeout < 5000) ->
+try_start_tcp_connect(RH, Opts, Sup, Timeout, Error0) when (Timeout < 5000) ->
     Sleep = random(Timeout) + 100,
     d("try tcp connect (~p,~p)", [Timeout, Sleep]),
     case megaco_tcp:connect(Sup, Opts) of
@@ -978,13 +993,13 @@ try_start_tcp_connect(RH, Sup, Opts, Timeout, Error0) when (Timeout < 5000) ->
 	Error1 when Error0 =:= noError -> % Keep the first error
 	    d("failed connecting [1]: ~p", [Error1]),
 	    sleep(Sleep),
-	    try_start_tcp_connect(RH, Sup, Opts, Timeout*2, Error1);
+	    try_start_tcp_connect(RH, Opts, Sup, Timeout*2, Error1);
 	Error2 ->	
 	    d("failed connecting [2]: ~p", [Error2]),
 	    sleep(Sleep),
-	    try_start_tcp_connect(RH, Sup, Opts, Timeout*2, Error0)
+	    try_start_tcp_connect(RH, Opts, Sup, Timeout*2, Error0)
     end;
-try_start_tcp_connect(_RH, Sup, _Opts, _Timeout, Error) ->
+try_start_tcp_connect(_RH, _Opts, Sup, _Timeout, Error) ->
     megaco_tcp:stop_transport(Sup),
     throw({error, {megaco_tcp_connect, Error}}).
     
@@ -995,25 +1010,45 @@ megaco_tcp_connect(RH, SendHandle, ControlPid) ->
     d("megaco connected: ~p", [CH]),    
     {ok, CH}.
 
-start_udp(MgcPort, MgcHost, RH, TO) ->
+start_udp(IB, RH, TO, MgcPort, MgcHost) ->
     d("start udp transport (~p)", [MgcPort]),
     case megaco_udp:start_transport() of
 	{ok, Sup} ->
 	    d("udp transport started: ~p", [Sup]),
-	    Opts = [{port, 0}, {receive_handle, RH}] ++ TO,
-	    d("udp open", []),
-	    case megaco_udp:open(Sup, Opts) of
-		{ok, Handle, ControlPid} ->
-		    d("udp opened: ~p, ~p", [Handle, ControlPid]),
-		    megaco_udp_connect(MgcPort, MgcHost, 
-				       RH, Handle, ControlPid);
-		{error, Reason} ->
-                    throw({error, {megaco_udp_open, Reason}})
-	    end;
+            start_udp_open(IB, RH, TO, MgcPort, MgcHost, Sup);
+	    %% Opts = [{inet_backend, IB}, {port, 0}, {receive_handle, RH}] ++ TO,
+	    %% d("udp open", []),
+	    %% case megaco_udp:open(Sup, Opts) of
+	    %%     {ok, Handle, ControlPid} ->
+	    %%         d("udp opened: ~p, ~p", [Handle, ControlPid]),
+	    %%         megaco_udp_connect(IB,
+            %%                            MgcPort, MgcHost, 
+	    %%     		       RH, Handle, ControlPid);
+	    %%     {error, Reason} ->
+            %%         throw({error, {megaco_udp_open, Reason}})
+	    %% end;
         {error, Reason} ->
             throw({error, {megaco_udp_start_transport, Reason}})
     end.
 
+start_udp_open(IB, RH, TO, MgcPort, MgcHost, Sup) ->
+    Opts = [{inet_backend, IB}, {port, 0}, {receive_handle, RH}] ++ TO,
+    try_start_udp_open(RH, Opts, MgcPort, MgcHost, Sup).
+
+try_start_udp_open(RH, Opts, MgcPort, MgcHost, Sup) ->
+    d("udp open", []),
+    case megaco_udp:open(Sup, Opts) of
+        {ok, Handle, ControlPid} ->
+            d("udp opened: ~p, ~p", [Handle, ControlPid]),
+            megaco_udp_connect(MgcPort, MgcHost, 
+                               RH, Handle, ControlPid);
+        {error, Reason} ->
+            megaco_udp:stop_transport(Sup),
+            throw({error, {megaco_udp_open, Reason}})
+    end.
+    
+    
+
 megaco_udp_connect(MgcPort, MgcHost, RH, Handle, ControlPid) ->
     MgcMid     = preliminary_mid,
     SendHandle = megaco_udp:create_send_handle(Handle, MgcHost, MgcPort),
diff --git a/lib/megaco/test/megaco_test_mgc.erl b/lib/megaco/test/megaco_test_mgc.erl
index a7d0731b0f..74fd9fc7fc 100644
--- a/lib/megaco/test/megaco_test_mgc.erl
+++ b/lib/megaco/test/megaco_test_mgc.erl
@@ -57,6 +57,8 @@
 -include_lib("megaco/include/megaco.hrl").
 -include_lib("megaco/include/megaco_message_v1.hrl").
 
+-define(NO_ERROR, 'no error').
+
 -define(A4444, ["11111111", "00000000", "00000000"]).
 -define(A4445, ["11111111", "00000000", "11111111"]).
 -define(A5555, ["11111111", "11111111", "00000000"]).
@@ -65,18 +67,19 @@
 -define(valid_actions, 
 	[ignore, pending, pending_ignore, discard_ack, handle_ack, handle_pending_ack, handle_sloppy_ack]).
 
--record(mgc, {parent      = undefined,
-	      tcp_sup     = undefined,
-	      udp_sup     = undefined,
-	      req_action  = discard_ack,
-	      req_timeout = 0,
-	      mid         = undefined,
-	      ack_info    = undefined,
-	      abort_info  = undefined,
-	      req_info    = undefined,
-	      mg          = [],
+-record(mgc, {parent       = undefined,
+              inet_backend = default,
+	      tcp_sup      = undefined,
+	      udp_sup      = undefined,
+	      req_action   = discard_ack,
+	      req_timeout  = 0,
+	      mid          = undefined,
+	      ack_info     = undefined,
+	      abort_info   = undefined,
+	      req_info     = undefined,
+	      mg           = [],
 	      dsi_timer,
-              evs         = []}).
+              evs          = []}).
 
 -define(EVS_MAX, 10).
 
@@ -330,13 +333,14 @@ mgc(Parent, Verbosity, Config) ->
     case (catch init(Config)) of
 	{error, Reason} ->
 	    exit(Reason);
-	{Mid, TcpSup, UdpSup, DSITimer} ->
+	{IB, Mid, TcpSup, UdpSup, DSITimer} ->
 	    notify_started(Parent),
-	    S = #mgc{parent    = Parent, 
-		     tcp_sup   = TcpSup, 
-		     udp_sup   = UdpSup, 
-		     mid       = Mid,
-		     dsi_timer = DSITimer},
+	    S = #mgc{parent       = Parent, 
+		     tcp_sup      = TcpSup, 
+		     udp_sup      = UdpSup, 
+		     mid          = Mid,
+		     dsi_timer    = DSITimer,
+                     inet_backend = IB},
 	    i("mgc -> started"),
 	    display_system_info("at start "),
 	    loop(evs(S, started))
@@ -345,10 +349,15 @@ mgc(Parent, Verbosity, Config) ->
 init(Config) ->
     d("init -> entry"),
     random_init(),
-    Mid = get_conf(local_mid, Config),
+
+    IB  = get_conf(inet_backend, Config, default),
+    Mid = get_conf(local_mid,    Config),
     RI  = get_conf(receive_info, Config),
 
-    d("init -> maybe start the display system info timer"),
+    d("init -> "
+      "~n      Inet Backend: ~p"
+      "~n      Mid:          ~p"
+      "~n      RI:           ~p", [IB, Mid, RI]),
     DSITimer = 
 	case get_conf(display_system_info, Config, undefined) of
 	    Time when is_integer(Time) ->
@@ -358,6 +367,7 @@ init(Config) ->
 		undefined
 	end,
     Conf0 = lists:keydelete(display_system_info, 1, Config),
+    Conf1 = lists:keydelete(inet_backend,        1, Conf0),
 
     d("init -> start megaco"),
     application:start(megaco),
@@ -373,12 +383,12 @@ init(Config) ->
 	_ ->
 	    ok
     end,
-    Conf1 = lists:keydelete(megaco_trace,    1, Conf0),
+    Conf2 = lists:keydelete(megaco_trace,    1, Conf1),
 
     d("init -> start megaco user"),
-    Conf2 = lists:keydelete(local_mid,    1, Conf1),
-    Conf3 = lists:keydelete(receive_info, 1, Conf2),
-    ok = megaco:start_user(Mid, Conf3),
+    Conf3 = lists:keydelete(local_mid,    1, Conf2),
+    Conf4 = lists:keydelete(receive_info, 1, Conf3),
+    ok = megaco:start_user(Mid, Conf4),
 
     d("init -> update user info (user_mod)"),
     ok = megaco:update_user_info(Mid, user_mod,  ?MODULE),
@@ -392,8 +402,8 @@ init(Config) ->
     Transports = parse_receive_info(RI, RH),
 
     d("init -> start transports"),
-    {Tcp, Udp} = start_transports(Transports),
-    {Mid, Tcp, Udp, DSITimer}.
+    {Tcp, Udp} = start_transports(IB, Transports),
+    {IB, Mid, Tcp, Udp, DSITimer}.
     
 loop(S) ->
     d("loop -> await request"),
@@ -722,11 +732,11 @@ parse_receive_info1(RI, RH) ->
 %%         send/receive port (udp). 
 %% The second step *may* need to be repeated!
 %% --------------------------------------------------------
-start_transports([]) ->
+start_transports(_, []) ->
     throw({error, no_transport});
-start_transports(Transports) when is_list(Transports) ->
+start_transports(IB, Transports) when is_list(Transports) ->
     {Tcp, Udp} = start_transports1(Transports, undefined, undefined),
-    ok = start_transports2(Transports, Tcp, Udp),
+    ok = start_transports2(IB, Transports, Tcp, Udp),
     {Tcp, Udp}.
     
 start_transports1([], Tcp, Udp) ->
@@ -760,28 +770,29 @@ start_transports1([{_TO, _Port, RH}|Transports], Tcp, Udp)
 start_transports1([_|Transports], Tcp, Udp) ->
     start_transports1(Transports, Tcp, Udp).
 
-start_transports2([], _, _) ->
+start_transports2(_, [], _, _) ->
     ok;
-start_transports2([{TO, Port, RH}|Transports], Tcp, Udp) 
+start_transports2(IB, [{TO, Port, RH}|Transports], Tcp, Udp) 
   when RH#megaco_receive_handle.send_mod =:= megaco_tcp ->
-    start_tcp(TO, RH, Port, Tcp),
-    start_transports2(Transports, Tcp, Udp);
-start_transports2([{TO, Port, RH}|Transports], Tcp, Udp) 
+    start_tcp(IB, TO, RH, Port, Tcp),
+    start_transports2(IB, Transports, Tcp, Udp);
+start_transports2(IB, [{TO, Port, RH}|Transports], Tcp, Udp) 
   when RH#megaco_receive_handle.send_mod =:= megaco_udp ->
-    start_udp(TO, RH, Port, Udp),
-    start_transports2(Transports, Tcp, Udp).
+    start_udp(IB, TO, RH, Port, Udp),
+    start_transports2(IB, Transports, Tcp, Udp).
 
-start_tcp(TO, RH, Port, Sup) ->
+start_tcp(IB, TO, RH, Port, Sup) ->
     d("start tcp transport"),
-    start_tcp(TO, RH, Port, Sup, 250).
+    start_tcp(IB, TO, RH, Port, Sup, 250).
 
-start_tcp(TO, RH, Port, Sup, Timeout) 
+start_tcp(IB, TO, RH, Port, Sup, Timeout) 
   when is_pid(Sup) andalso is_integer(Timeout) andalso (Timeout > 0) ->
     d("tcp listen on ~p", [Port]),
-    Opts = [{port,           Port}, 
+    Opts = [{inet_backend,   IB},
+            {port,           Port}, 
 	    {receive_handle, RH}, 
 	    {tcp_options,    [{nodelay, true}]}] ++ TO,
-    try_start_tcp(Sup, Opts, Timeout, noError).
+    try_start_tcp(Sup, Opts, Timeout, ?NO_ERROR).
 
 try_start_tcp(Sup, Opts, Timeout, Error0) when (Timeout < 5000) ->
     Sleep = random(Timeout) + 100,
@@ -790,7 +801,7 @@ try_start_tcp(Sup, Opts, Timeout, Error0) when (Timeout < 5000) ->
 	ok ->
 	    d("listen socket created", []),
 	    Sup;
-	Error1 when Error0 =:= noError -> % Keep the first error
+	Error1 when Error0 =:= ?NO_ERROR -> % Keep the first error
 	    d("failed creating listen socket [1]: ~p", [Error1]),
 	    sleep(Sleep),
 	    try_start_tcp(Sup, Opts, Timeout*2, Error1);
@@ -809,14 +820,16 @@ try_start_tcp(Sup, _Opts, _Timeout, Error) ->
     end.
 
 
-start_udp(TO, RH, Port, Sup) ->
+start_udp(IB, TO, RH, Port, Sup) ->
     d("start udp transport"),
-    start_udp(TO, RH, Port, Sup, 250).
+    start_udp(IB, TO, RH, Port, Sup, 250).
 
-start_udp(TO, RH, Port, Sup, Timeout) ->
+start_udp(IB, TO, RH, Port, Sup, Timeout) ->
     d("udp open ~p", [Port]),
-    Opts = [{port, Port}, {receive_handle, RH}] ++ TO,
-    try_start_udp(Sup, Opts, Timeout, noError).
+    Opts = [{inet_backend,   IB},
+            {port,           Port},
+            {receive_handle, RH}] ++ TO,
+    try_start_udp(Sup, Opts, Timeout, ?NO_ERROR).
 
 try_start_udp(Sup, Opts, Timeout, Error0) when (Timeout < 5000) ->
     d("try open udp socket (~p)", [Timeout]),
@@ -824,7 +837,7 @@ try_start_udp(Sup, Opts, Timeout, Error0) when (Timeout < 5000) ->
 	{ok, _SendHandle, _ControlPid} ->
 	    d("port opened", []),
 	    Sup;
-	Error1 when Error0 =:= noError -> % Keep the first error
+	Error1 when Error0 =:= ?NO_ERROR -> % Keep the first error
 	    d("failed open port [1]: ~p", [Error1]),
 	    sleep(Timeout),
 	    try_start_udp(Sup, Opts, Timeout*2, Error1);