Create GSMTAP sink to avoid ICMP errors

Change-Id: I1b103bb16d2e9f0bc6296a2feda138364ed640e2
---
M src/logger_gsmtap.erl
1 file changed, 43 insertions(+), 8 deletions(-)


git pull ssh://gerrit.osmocom.org:29418/erlang/logger_gsmtap refs/changes/53/39553/1

diff --git a/src/logger_gsmtap.erl b/src/logger_gsmtap.erl
index 570952d..d4ce411 100644
--- a/src/logger_gsmtap.erl
+++ b/src/logger_gsmtap.erl
@@ -21,6 +21,7 @@
 -export([init/1,
          handle_call/3,
          handle_cast/2,
+         handle_info/2,
          terminate/2]).
 
 -define(GSMTAP_PORT, 4729).
@@ -56,11 +57,8 @@
 %% ------------------------------------------------------------------
 
 init([LAddr, RAddr, AppName]) ->
-    {ok, Sock} = gen_udp:open(0, [binary,
-                                  {ip, LAddr}, %% bind addr
-                                  {reuseaddr, true}]),
-    ok = gen_udp:connect(Sock, RAddr, ?GSMTAP_PORT),
-    {ok, #{sock => Sock,
+    {ok, #{sock_source => create_source(LAddr, RAddr),
+           sock_sink => create_sink(RAddr),
            app_name => AppName}}.
 
 
@@ -69,7 +67,7 @@
 
 
 handle_cast({log, LogEvent},
-            #{sock := Sock,
+            #{sock_source := Sock,
               app_name := AppName} = S) ->
     PDU = gsmtap_pdu(LogEvent#{app_name => AppName}),
     gen_udp:send(Sock, PDU),
@@ -79,8 +77,13 @@
     {noreply, S}.
 
 
-terminate(_Reason, #{sock := Sock}) ->
-    gen_udp:close(Sock),
+handle_info(_Info, S) ->
+    {noreply, S}.
+
+
+terminate(_Reason, S) ->
+    close(maps:get(sock_source, S)),
+    close(maps:get(sock_sink, S)),
     ok.
 
 
@@ -88,6 +91,38 @@
 %% private API
 %% ------------------------------------------------------------------
 
+-spec create_source(LAddr, RAddr) -> gen_udp:socket()
+    when LAddr :: inet:ip_address(),
+         RAddr :: inet:ip_address().
+create_source(LAddr, RAddr) ->
+    {ok, Sock} = gen_udp:open(0, [binary,
+                                  {ip, LAddr}, %% bind addr
+                                  {reuseaddr, true},
+                                  {active, false}]),
+    ok = gen_udp:connect(Sock, RAddr, ?GSMTAP_PORT),
+    Sock.
+
+
+-spec create_sink(inet:ip_address()) -> gen_udp:socket() | nope.
+create_sink(Addr) ->
+    %% it's not critical if gen_udp:open/2 fails
+    case gen_udp:open(?GSMTAP_PORT, [binary,
+                                     {ip, Addr}, %% bind addr
+                                     {reuseaddr, true},
+                                     {active, false}]) of
+        {ok, Sock} -> Sock;
+        _ -> nope
+    end.
+
+
+-spec close(nope | gen_udp:socket()) -> ok.
+close(nope) ->
+    ok;
+
+close(Sock) ->
+    gen_udp:close(Sock).
+
+
 -spec gsmtap_pdu(map()) -> binary().
 gsmtap_pdu(#{msg := Msg,
              level := Level,

