bridging: Ensure locking during snapshot creation

While the vast majority of bridge snapshot creation is locked properly,
there are currently some instances that are not. This adds the missing
locking to ensure bridge state is not malleable during snapshot
creation.

(closes issue ASTERISK-22904)
Review: https://reviewboard.asterisk.org/r/3415/
Reported by: Matt Jordan
........

Merged revisions 412193 from http://svn.asterisk.org/svn/asterisk/branches/12


git-svn-id: http://svn.asterisk.org/svn/asterisk/trunk@412194 f38db490-d61c-443f-a65b-d21fe96a405b

apps/app_confbridge.c

@@ -453,10 +453,13 @@ static void send_conf_stasis(struct confbridge_conference *conference, struct as
 		ast_json_object_update(json_object, extras);
 	}
 
+	ast_bridge_lock(conference->bridge);
 	msg = ast_bridge_blob_create(type,
 		conference->bridge,
 		chan,
 		json_object);
+	ast_bridge_unlock(conference->bridge);
+
 	if (!msg) {
 		return;
 	}

include/asterisk/stasis_bridges.h

@@ -65,6 +65,8 @@ struct ast_bridge_snapshot {
  * \brief Generate a snapshot of the bridge state. This is an ao2 object, so
  * ao2_cleanup() to deallocate.
  *
+ * \pre Bridge is locked
+ *
  * \param bridge The bridge from which to generate a snapshot
  *
  * \retval AO2 refcounted snapshot on success
@@ -136,6 +138,8 @@ struct stasis_cache *ast_bridge_cache(void);
  * \since 12
  * \brief Publish the state of a bridge
  *
+ * \pre Bridge is locked
+ *
  * \param bridge The bridge for which to publish state
  */
 void ast_bridge_publish_state(struct ast_bridge *bridge);
@@ -158,6 +162,8 @@ struct stasis_message_type *ast_bridge_merge_message_type(void);
  * \since 12
  * \brief Publish a bridge merge
  *
+ * \pre Bridges involved are locked
+ *
  * \param to The bridge to which channels are being added
  * \param from The bridge from which channels are being removed
  */
@@ -281,7 +287,7 @@ struct stasis_message_type *ast_blind_transfer_type(void);
 /*!
  * \brief Publish a blind transfer event
  *
- * \pre No channels or bridges are locked
+ * \pre Bridges involved are locked. Channels involved are not locked.
  *
  * \param is_external Whether the blind transfer was initiated externally (e.g. via AMI or native protocol)
  * \param result The success or failure of the transfer
@@ -346,7 +352,7 @@ struct stasis_message_type *ast_attended_transfer_type(void);
  * Publish an \ref ast_attended_transfer_message with the dest_type set to
  * \c AST_ATTENDED_TRANSFER_DEST_FAIL.
  *
- * \pre No channels or bridges are locked
+ * \pre Bridges involved are locked. Channels involved are not locked.
  *
  * \param is_external Indicates if the transfer was initiated externally
  * \param result The result of the transfer. Will always be a type of failure.
@@ -369,7 +375,7 @@ void ast_bridge_publish_attended_transfer_fail(int is_external, enum ast_transfe
  *
  * In either case, two bridges enter, one leaves.
  *
- * \pre No channels or bridges are locked
+ * \pre Bridges involved are locked. Channels involved are not locked.
  *
  * \param is_external Indicates if the transfer was initiated externally
  * \param result The result of the transfer.
@@ -390,7 +396,7 @@ void ast_bridge_publish_attended_transfer_bridge_merge(int is_external, enum ast
  * this results from merging two bridges together. The difference is that a
  * transferer channel survives the bridge merge
  *
- * \pre No channels or bridges are locked
+ * \pre Bridges involved are locked. Channels involved are not locked.
  *
  * \param is_external Indicates if the transfer was initiated externally
  * \param result The result of the transfer.
@@ -413,7 +419,7 @@ void ast_bridge_publish_attended_transfer_threeway(int is_external, enum ast_tra
  * \li A transferee channel leaving a bridge to run an app
  * \li A bridge of transferees running an app (via a local channel)
  *
- * \pre No channels or bridges are locked
+ * \pre Bridges involved are locked. Channels involved are not locked.
  *
  * \param is_external Indicates if the transfer was initiated externally
  * \param result The result of the transfer.
@@ -438,7 +444,7 @@ void ast_bridge_publish_attended_transfer_app(int is_external, enum ast_transfer
  * When this type of transfer occurs, the two bridges continue to exist after the
  * transfer and a local channel is used to link the two bridges together.
  *
- * \pre No channels or bridges are locked
+ * \pre Bridges involved are locked. Channels involved are not locked.
  *
  * \param is_external Indicates if the transfer was initiated externally
  * \param result The result of the transfer.

main/bridge.c

@@ -615,7 +615,10 @@ static struct stasis_message *create_bridge_snapshot_message(struct ast_bridge *
 {
 	RAII_VAR(struct ast_bridge_snapshot *, snapshot, NULL, ao2_cleanup);
 
+	ast_bridge_lock(bridge);
 	snapshot = ast_bridge_snapshot_create(bridge);
+	ast_bridge_unlock(bridge);
+
 	if (!snapshot) {
 		return NULL;
 	}
@@ -689,7 +692,9 @@ struct ast_bridge *bridge_register(struct ast_bridge *bridge)
 {
 	if (bridge) {
 		bridge->construction_completed = 1;
+		ast_bridge_lock(bridge);
 		ast_bridge_publish_state(bridge);
+		ast_bridge_unlock(bridge);
 		if (!ao2_link(bridges, bridge)) {
 			ast_bridge_destroy(bridge, 0);
 			bridge = NULL;
@@ -4067,7 +4072,9 @@ static void publish_blind_transfer(int is_external, enum ast_transfer_result res
 	struct ast_bridge_channel_pair pair;
 	pair.channel = transferer;
 	pair.bridge = bridge;
+	ast_bridge_lock(bridge);
 	ast_bridge_publish_blind_transfer(is_external, result, &pair, context, exten);
+	ast_bridge_unlock(bridge);
 }
 
 enum ast_transfer_result ast_bridge_transfer_blind(int is_external,
@@ -4294,7 +4301,7 @@ enum ast_transfer_result ast_bridge_transfer_attended(struct ast_channel *to_tra
 	RAII_VAR(struct ast_bridge_channel *, to_target_bridge_channel, NULL, ao2_cleanup);
 	RAII_VAR(struct ao2_container *, channels, NULL, ao2_cleanup);
 	RAII_VAR(struct ast_channel *, transferee, NULL, ao2_cleanup);
-	struct ast_bridge *the_bridge;
+	struct ast_bridge *the_bridge = NULL;
 	struct ast_channel *chan_bridged;
 	struct ast_channel *chan_unbridged;
 	int transfer_prohibited;
@@ -4412,8 +4419,10 @@ enum ast_transfer_result ast_bridge_transfer_attended(struct ast_channel *to_tra
 	set_transfer_variables_all(to_transferee, channels, 1);
 
 	if (do_bridge_transfer) {
-		 res = attended_transfer_bridge(chan_bridged, chan_unbridged, the_bridge, NULL, &publication);
-		 goto end;
+		ast_bridge_lock(the_bridge);
+		res = attended_transfer_bridge(chan_bridged, chan_unbridged, the_bridge, NULL, &publication);
+		ast_bridge_unlock(the_bridge);
+		goto end;
 	}
 
 	transferee = get_transferee(channels, chan_bridged);
@@ -4430,15 +4439,30 @@ enum ast_transfer_result ast_bridge_transfer_attended(struct ast_channel *to_tra
 
 	ast_bridge_remove(the_bridge, chan_bridged);
 
+	ast_bridge_lock(the_bridge);
 	publish_attended_transfer_app(&publication, app);
+	ast_bridge_unlock(the_bridge);
 	res = AST_BRIDGE_TRANSFER_SUCCESS;
 
 end:
 	/* All successful transfer paths have published an appropriate stasis message.
 	 * All failure paths have deferred publishing a stasis message until this point
 	 */
 	if (res != AST_BRIDGE_TRANSFER_SUCCESS) {
+		if (to_transferee_bridge && to_target_bridge) {
+			ast_bridge_lock_both(to_transferee_bridge, to_target_bridge);
+		} else if (the_bridge) {
+			ast_bridge_lock(the_bridge);
+		}
+
 		publish_attended_transfer_fail(&publication, res);
+
+		if (to_transferee_bridge && to_target_bridge) {
+			ast_bridge_unlock(to_transferee_bridge);
+			ast_bridge_unlock(to_target_bridge);
+		} else if (the_bridge) {
+			ast_bridge_unlock(the_bridge);
+		}
 	}
 	stasis_publish_data_cleanup(&publication);
 	return res;

main/bridge_basic.c

@@ -1534,8 +1534,11 @@ static void publish_transfer_success(struct attended_transfer_properties *props)
 		.bridge = props->target_bridge,
 	};
 
+	ast_bridge_lock_both(transferee.bridge, transfer_target.bridge);
 	ast_bridge_publish_attended_transfer_bridge_merge(0, AST_BRIDGE_TRANSFER_SUCCESS,
 			&transferee, &transfer_target, props->transferee_bridge);
+	ast_bridge_unlock(transferee.bridge);
+	ast_bridge_unlock(transfer_target.bridge);
 }
 
 /*!
@@ -1556,8 +1559,11 @@ static void publish_transfer_threeway(struct attended_transfer_properties *props
 		.bridge = props->transferee_bridge,
 	};
 
+	ast_bridge_lock_both(transferee.bridge, transfer_target.bridge);
 	ast_bridge_publish_attended_transfer_threeway(0, AST_BRIDGE_TRANSFER_SUCCESS,
 			&transferee, &transfer_target, &threeway);
+	ast_bridge_unlock(transferee.bridge);
+	ast_bridge_unlock(transfer_target.bridge);
 }
 
 /*!
@@ -1574,8 +1580,11 @@ static void publish_transfer_fail(struct attended_transfer_properties *props)
 		.bridge = props->target_bridge,
 	};
 
+	ast_bridge_lock_both(transferee.bridge, transfer_target.bridge);
 	ast_bridge_publish_attended_transfer_fail(0, AST_BRIDGE_TRANSFER_FAIL,
 			&transferee, &transfer_target);
+	ast_bridge_unlock(transferee.bridge);
+	ast_bridge_unlock(transfer_target.bridge);
 }
 
 /*!

res/ari/resource_bridges.c

@@ -746,7 +746,10 @@ void ast_ari_bridges_create(struct ast_variable *headers,
 		return;
 	}
 
+	ast_bridge_lock(bridge);
 	snapshot = ast_bridge_snapshot_create(bridge);
+	ast_bridge_unlock(bridge);
+
 	if (!snapshot) {
 		ast_ari_response_error(
 			response, 500, "Internal Error",
@@ -792,7 +795,10 @@ void ast_ari_bridges_create_or_update_with_id(struct ast_variable *headers,
 		return;
 	}
 
+	ast_bridge_lock(bridge);
 	snapshot = ast_bridge_snapshot_create(bridge);
+	ast_bridge_unlock(bridge);
+
 	if (!snapshot) {
 		ast_ari_response_error(
 			response, 500, "Internal Error",

tests/test_cel.c

@@ -1213,8 +1213,10 @@ AST_TEST_DEFINE(test_cel_blind_transfer)
 
 	pair.bridge = bridge;
 	pair.channel = chan_alice;
+	ast_bridge_lock(bridge);
 	ast_bridge_publish_blind_transfer(1, AST_BRIDGE_TRANSFER_SUCCESS,
 		&pair, "transfer_context", "transfer_extension");
+	ast_bridge_unlock(bridge);
 	BLINDTRANSFER_EVENT(chan_alice, bridge, "transfer_extension", "transfer_context");
 
 	BRIDGE_EXIT(chan_alice, bridge);