Allow transfer loops without allowing forwarding loops

We try to avoid the situation where two phones may be forwarded to each other
causing an infinite loop by storing each dialed interface in a channel
datastore and checking the list before dialing out. This works, but currently
breaks situations like A calls B, A transfers B to C, B transfers C to A, and A
transfers C to B. Since human interaction is happening here and not an
automated forwarding loop, it should be allowed.

This patch removes the dialed_interfaces datastore when a call is bridged (a
suggestion from the brilliant mmichelson). If a call is being bridged, it
should be safe to assume that we aren't stuck in a loop.

Since we are now handling this is the bridge code, the previous attempts at
handling it in app_dial and app_queue are removed.

Review: https://reviewboard.asterisk.org/r/1195/


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.4@315596 65c4cc65-6c06-0410-ace0-fbb531ad65f3

apps/app_dial.c

@@ -1453,14 +1453,6 @@ static int dial_exec_full(struct ast_channel *chan, void *data, struct ast_flags
 	time(&start_time);
 	peer = wait_for_answer(chan, outgoing, &to, peerflags, &sentringing, status, sizeof(status), numbusy, numnochan, numcongestion, ast_test_flag(&opts, OPT_PRIORITY_JUMP), &result);
 
-	/* The ast_channel_datastore_remove() function could fail here if the
-	 * datastore was moved to another channel during a masquerade. If this is
-	 * the case, don't free the datastore here because later, when the channel
-	 * to which the datastore was moved hangs up, it will attempt to free this
-	 * datastore again, causing a crash
-	 */
-	if (!ast_channel_datastore_remove(chan, datastore))
-		ast_channel_datastore_free(datastore);
 	if (!peer) {
 		if (result) {
 			res = result;

apps/app_queue.c

@@ -3047,17 +3047,6 @@ static int try_calling(struct queue_ent *qe, const char *options, char *announce
 	if (need_weight)
 		AST_LIST_UNLOCK(&queues);
 	lpeer = wait_for_answer(qe, outgoing, &to, &digit, numbusies, ast_test_flag(&(bridge_config.features_caller), AST_FEATURE_DISCONNECT), forwardsallowed);
-	/* The ast_channel_datastore_remove() function could fail here if the
-	 * datastore was moved to another channel during a masquerade. If this is
-	 * the case, don't free the datastore here because later, when the channel
-	 * to which the datastore was moved hangs up, it will attempt to free this
-	 * datastore again, causing a crash
-	 */
-	ast_channel_lock(qe->chan);
-	if (datastore && !ast_channel_datastore_remove(qe->chan, datastore)) {
-		ast_channel_datastore_free(datastore);
-	}
-	ast_channel_unlock(qe->chan);
 	ao2_lock(qe->parent);
 	if (qe->parent->strategy == QUEUE_STRATEGY_RRMEMORY || qe->parent->strategy == QUEUE_STRATEGY_RRORDERED) {
 		store_next(qe, outgoing);

res/res_features.c

@@ -2092,6 +2092,22 @@ static void add_features_datastores(struct ast_channel *caller, struct ast_chann
 	return;
 }
 
+static void clear_dialed_interfaces(struct ast_channel *chan)
+{
+	struct ast_datastore *di_datastore;
+
+	ast_channel_lock(chan);
+	if ((di_datastore = ast_channel_datastore_find(chan, &dialed_interface_info, NULL))) {
+		if (option_debug) {
+			ast_log(LOG_DEBUG, "Removing dialed interfaces datastore on %s since we're bridging\n", chan->name);
+		}
+		if (!ast_channel_datastore_remove(chan, di_datastore)) {
+			ast_channel_datastore_free(di_datastore);
+		}
+	}
+	ast_channel_unlock(chan);
+}
+
 int ast_bridge_call(struct ast_channel *chan,struct ast_channel *peer,struct ast_bridge_config *config)
 {
 	/* Copy voice back and forth between the two channels.  Give the peer
@@ -2249,6 +2265,12 @@ int ast_bridge_call(struct ast_channel *chan,struct ast_channel *peer,struct ast
 		ast_clear_flag(bridge_cdr, AST_CDR_FLAG_DIALED);
 	}
 
+	/* If we are bridging a call, stop worrying about forwarding loops. We presume that if
+	 * a call is being bridged, that the humans in charge know what they're doing. If they
+	 * don't, well, what can we do about that? */
+	clear_dialed_interfaces(chan);
+	clear_dialed_interfaces(peer);
+
 	for (;;) {
 		struct ast_channel *other;	/* used later */