bridge : Fix one-way direct-media when early bridging with native_rtp

When two channels were early bridged in a native_rtp bridge, the RTP description
on one side was not updated when the other side answered.
This patch forbids non-answered channels to enter a native_rtp bridge, and
triggers a bridge reconfiguration when an ANSWER frame is received.

ASTERISK-27257

Change-Id: If1aaee1b4ed9658a1aa91ab715ee0a6413b878df

bridges/bridge_native_rtp.c

@@ -598,7 +598,8 @@ static int native_rtp_framehook_consume(void *data, enum ast_frame_type type)
  */
 static int native_rtp_bridge_capable(struct ast_channel *chan)
 {
-	return !ast_channel_has_hook_requiring_audio(chan);
+	return !ast_channel_has_hook_requiring_audio(chan)
+			&& ast_channel_state(chan) == AST_STATE_UP;
 }
 
 /*!

include/asterisk/bridge_technology.h

@@ -108,11 +108,13 @@ struct ast_bridge_technology {
 	 *
 	 * \note On entry, bridge is already locked.
 	 *
-	 * \note The bridge technology must tollerate a failed to join channel
+	 * \note The bridge technology must tolerate a failed to join channel
 	 * until it can be kicked from the bridge.
 	 *
 	 * \note A channel may be in a suspended state already when joining a bridge
 	 * technology. The technology must handle this case.
+	 *
+	 * \note A channel may not be answered when joining a bridge technology.
 	 */
 	int (*join)(struct ast_bridge *bridge, struct ast_bridge_channel *bridge_channel);
 	/*!

main/bridge_channel.c

@@ -2313,6 +2313,10 @@ static void bridge_channel_handle_control(struct ast_bridge_channel *bridge_chan
 	case AST_CONTROL_ANSWER:
 		if (ast_channel_state(chan) != AST_STATE_UP) {
 			ast_answer(chan);
+			ast_bridge_channel_lock_bridge(bridge_channel);
+			bridge_channel->bridge->reconfigured = 1;
+			bridge_reconfigured(bridge_channel->bridge, 0);
+			ast_bridge_unlock(bridge_channel->bridge);
 		} else {
 			ast_indicate(chan, -1);
 		}