Merge "res_fax: gateway sends T.38 request to both endpoints if V.21 detected"

res/res_fax.c

@@ -2921,6 +2921,9 @@ static int fax_gateway_start(struct fax_gateway *gateway, struct ast_fax_session
 		return 0;
 	}
 
+	/* if we start gateway we don't need v21 detection sessions any more */
+	destroy_v21_sessions(gateway);
+
 	/* create the FAX session */
 	if (!(s = fax_session_new(details, chan, gateway->s, gateway->token))) {
 		gateway->token = NULL;
@@ -2962,7 +2965,7 @@ static int fax_gateway_start(struct fax_gateway *gateway, struct ast_fax_session
 }
 
 /*! \pre chan is locked on entry */
-static struct ast_frame *fax_gateway_request_t38(struct fax_gateway *gateway, struct ast_channel *chan, struct ast_frame *f)
+static struct ast_frame *fax_gateway_request_t38(struct fax_gateway *gateway, struct ast_channel *chan)
 {
 	struct ast_frame *fp;
 	struct ast_control_t38_parameters t38_parameters = {
@@ -2981,7 +2984,7 @@ static struct ast_frame *fax_gateway_request_t38(struct fax_gateway *gateway, st
 	if (!details) {
 		ast_log(LOG_ERROR, "no FAX session details found on chan %s for T.38 gateway session, odd\n", ast_channel_name(chan));
 		ast_framehook_detach(chan, gateway->framehook);
-		return f;
+		return NULL;
 	}
 
 	t38_parameters_fax_to_ast(&t38_parameters, &details->our_t38_parameters);
@@ -2989,7 +2992,7 @@ static struct ast_frame *fax_gateway_request_t38(struct fax_gateway *gateway, st
 
 	if (!(fp = ast_frisolate(&control_frame))) {
 		ast_log(LOG_ERROR, "error generating T.38 request control frame on chan %s for T.38 gateway session\n", ast_channel_name(chan));
-		return f;
+		return NULL;
 	}
 
 	gateway->t38_state = T38_STATE_NEGOTIATING;
@@ -3018,17 +3021,40 @@ static struct ast_frame *fax_gateway_detect_v21(struct fax_gateway *gateway, str
 
 	if (gateway->detected_v21) {
 		enum ast_t38_state state_other;
+		enum ast_t38_state state_active;
+		struct ast_frame *fp;
 
 		destroy_v21_sessions(gateway);
 
 		ast_channel_unlock(chan);
+		state_active = ast_channel_get_t38_state(active);
 		state_other = ast_channel_get_t38_state(other);
 		ast_channel_lock(chan);
-		if (state_other == T38_STATE_UNKNOWN) {
-			ast_debug(1, "detected v21 preamble from %s\n", ast_channel_name(active));
-			return fax_gateway_request_t38(gateway, chan, f);
+
+		ast_debug(1, "detected v21 preamble from %s\n", ast_channel_name(active));
+
+		if (state_active == T38_STATE_UNKNOWN || state_other == T38_STATE_UNKNOWN) {
+			if (!(fp = fax_gateway_request_t38(gateway, chan))) {
+				return f;
+			}
+			/* May be called endpoint is improperly configured to rely on the calling endpoint
+			 * to initiate T.38 re-INVITEs, send T.38 negotiation request to called endpoint */
+			if (state_active == T38_STATE_UNKNOWN) {
+				ast_debug(1, "sending T.38 negotiation request to %s\n", ast_channel_name(active));
+				if (active == chan) {
+					ast_channel_unlock(chan);
+				}
+				ast_write(active, fp);
+				if (active == chan) {
+					ast_channel_lock(chan);
+				}
+			}
+			if (state_other == T38_STATE_UNKNOWN) {
+				ast_debug(1, "sending T.38 negotiation request to %s\n", ast_channel_name(other));
+				return fp;
+			}
 		} else {
-			ast_debug(1, "detected v21 preamble on %s, but %s does not support T.38 for T.38 gateway session\n", ast_channel_name(active), ast_channel_name(other));
+			ast_debug(1, "neither %s nor %s support T.38 for T.38 gateway session\n", ast_channel_name(active), ast_channel_name(other));
 		}
 	}
 
@@ -3190,7 +3216,7 @@ static struct ast_frame *fax_gateway_detect_t38(struct fax_gateway *gateway, str
 		ast_channel_lock(chan);
 		if (state_other == T38_STATE_UNKNOWN) {
 			gateway->t38_state = T38_STATE_UNAVAILABLE;
-		} else {
+		} else if (state_other != T38_STATE_NEGOTIATING) {
 			ast_framehook_detach(chan, details->gateway_id);
 			details->gateway_id = -1;