From 7d4e37a1805c97f20483b1b9cdb6ec5eb14aacc7 Mon Sep 17 00:00:00 2001
From: "Joshua C. Colp" <jcolp@sangoma.com>
Date: Tue, 16 Nov 2021 06:06:26 -0400
Subject: [PATCH] bridge: Deny full Local channel pair in bridge.
Local channels are made up of two pairs - the 1 and 2
sides. When a frame goes in one side, it comes out the
other. Back and forth. When both halves are in a
bridge this creates an infinite loop of frames.
This change makes it so that bridging no longer
allows both of these sides to exist in the same
bridge.
ASTERISK-29748
Change-Id: I29928b6de87cd9be996a77daccefd7c360fef651
---
main/bridge_channel.c | 25 +++++++++++++++++++++++++
1 file changed, 25 insertions(+)
diff --git a/main/bridge_channel.c b/main/bridge_channel.c
index 71739b7b0f..aefb76405a 100644
--- a/main/bridge_channel.c
+++ b/main/bridge_channel.c
@@ -57,6 +57,7 @@
#include "asterisk/sem.h"
#include "asterisk/stream.h"
#include "asterisk/message.h"
+#include "asterisk/core_local.h"
/*!
* \brief Used to queue an action frame onto a bridge channel and write an action frame into a bridge.
@@ -2862,6 +2863,7 @@ int bridge_channel_internal_join(struct ast_bridge_channel *bridge_channel)
int res = 0;
uint8_t indicate_src_change = 0;
struct ast_bridge_features *channel_features;
+ struct ast_channel *peer;
struct ast_channel *swap;
ast_debug(1, "Bridge %s: %p(%s) is joining\n",
@@ -2876,6 +2878,29 @@ int bridge_channel_internal_join(struct ast_bridge_channel *bridge_channel)
ast_channel_lock(bridge_channel->chan);
+ peer = ast_local_get_peer(bridge_channel->chan);
+ if (peer) {
+ struct ast_bridge *peer_bridge;
+
+ ast_channel_lock(peer);
+ peer_bridge = ast_channel_internal_bridge(peer);
+ ast_channel_unlock(peer);
+ ast_channel_unref(peer);
+
+ /* As we are only doing a pointer comparison we don't need the peer_bridge
+ * to be reference counted or locked.
+ */
+ if (peer_bridge == bridge_channel->bridge) {
+ ast_channel_unlock(bridge_channel->chan);
+ ast_bridge_unlock(bridge_channel->bridge);
+ ast_debug(1, "Bridge %s: %p(%s) denying Bridge join to prevent Local channel loop\n",
+ bridge_channel->bridge->uniqueid,
+ bridge_channel,
+ ast_channel_name(bridge_channel->chan));
+ return -1;
+ }
+ }
+
bridge_channel->read_format = ao2_bump(ast_channel_readformat(bridge_channel->chan));
bridge_channel->write_format = ao2_bump(ast_channel_writeformat(bridge_channel->chan));
--
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