Don't let a Local channel get bridged to itself

If a local channel gets bridged to itself, it becomes orphaned with no devices
left to actually tell it to hang up. This patch modifies local_fixup() to detect
this case and deny it.

Review: https://reviewboard.asterisk.org/r/934


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.4@288499 65c4cc65-6c06-0410-ace0-fbb531ad65f3

channels/chan_local.c

@@ -442,6 +442,15 @@ static int local_fixup(struct ast_channel *oldchan, struct ast_channel *newchan)
 		p->owner = newchan;
 	else
 		p->chan = newchan;
+
+	/* Do not let a masquerade cause a Local channel to be bridged to itself! */
+	if (p->owner->_bridge == p->chan || p->chan->_bridge == p->owner) {
+		ast_log(LOG_WARNING, "You can not bridge a Local channel to itself!\n");
+		ast_mutex_unlock(&p->lock);
+		ast_queue_hangup(newchan);
+		return -1;
+	}
+
 	ast_mutex_unlock(&p->lock);
 	return 0;
 }