log error code upon RTP socket error

daemon/call.c

@@ -86,10 +86,14 @@ static void unkernelize(struct peer *);
 static void stream_closed(int fd, void *p) {
 	struct streamrelay *r = p;
 	struct call *c;
+	int i;
+	socklen_t j;
 
 	c = r->up->up->call;
 
-	mylog(LOG_WARNING, LOG_PREFIX_C "Read error on RTP socket", LOG_PARAMS_C(c));
+	j = sizeof(i);
+	getsockopt(fd, SOL_SOCKET, SO_ERROR, &i, &j);
+	mylog(LOG_WARNING, LOG_PREFIX_C "Read error on RTP socket: %i (%s)", LOG_PARAMS_C(c), i, strerror(i));
 
 	call_destroy(c);
 }