res/res_pjsip: Fix localnet checks in pjsip, part 2.

In 45744fc53, I mistakenly broke SDP media address rewriting by
misinterpreting which address was checked in the localnet comparison.

Instead of checking the remote peer address to decide whether we need
media address rewriting, we check our local media address: if it's
local, then we rewrite. This feels awkward, but works and even made
directmedia work properly if you set local_net. (For the record: for
local peers, the SDP media rewrite code is not called, so the
comparison does no harm there.)

ASTERISK-27248 #close

Change-Id: I566be1c33f4d0a689567d451ed46bab9c3861d4f

res/res_pjsip_sdp_rtp.c

@@ -1807,7 +1807,7 @@ static void change_outgoing_sdp_stream_media_address(pjsip_tx_data *tdata, struc
 {
 	RAII_VAR(struct ast_sip_transport_state *, transport_state, ast_sip_get_transport_state(ast_sorcery_object_get_id(transport)), ao2_cleanup);
 	char host[NI_MAXHOST];
-	struct ast_sockaddr addr = { { 0, } };
+	struct ast_sockaddr our_sdp_addr = { { 0, } };
 
 	/* If the stream has been rejected there will be no connection line */
 	if (!stream->conn || !transport_state) {
@@ -1815,10 +1815,13 @@ static void change_outgoing_sdp_stream_media_address(pjsip_tx_data *tdata, struc
 	}
 
 	ast_copy_pj_str(host, &stream->conn->addr, sizeof(host));
-	ast_sockaddr_parse(&addr, host, PARSE_PORT_FORBID);
+	ast_sockaddr_parse(&our_sdp_addr, host, PARSE_PORT_FORBID);
 
-	/* Is the address within the SDP inside the same network? */
-	if (ast_sip_transport_is_local(transport_state, &addr)) {
+	/* Reversed check here. We don't check the remote endpoint being
+	 * in our local net, but whether our outgoing session IP is
+	 * local. If it is not, we won't do rewriting. No localnet
+	 * configured? Always rewrite. */
+	if (ast_sip_transport_is_nonlocal(transport_state, &our_sdp_addr) && transport_state->localnet) {
 		return;
 	}
 	ast_debug(5, "Setting media address to %s\n", ast_sockaddr_stringify_host(&transport_state->external_media_address));

res/res_pjsip_session.c

@@ -3976,12 +3976,16 @@ static void session_outgoing_nat_hook(pjsip_tx_data *tdata, struct ast_sip_trans
 
 	if (sdp->conn) {
 		char host[NI_MAXHOST];
-		struct ast_sockaddr addr = { { 0, } };
+		struct ast_sockaddr our_sdp_addr = { { 0, } };
 
 		ast_copy_pj_str(host, &sdp->conn->addr, sizeof(host));
-		ast_sockaddr_parse(&addr, host, PARSE_PORT_FORBID);
+		ast_sockaddr_parse(&our_sdp_addr, host, PARSE_PORT_FORBID);
 
-		if (ast_sip_transport_is_nonlocal(transport_state, &addr)) {
+		/* Reversed check here. We don't check the remote
+		 * endpoint being in our local net, but whether our
+		 * outgoing session IP is local. If it is, we'll do
+		 * rewriting. No localnet configured? Always rewrite. */
+		if (ast_sip_transport_is_local(transport_state, &our_sdp_addr) || !transport_state->localnet) {
 			ast_debug(5, "Setting external media address to %s\n", ast_sockaddr_stringify_host(&transport_state->external_media_address));
 			pj_strdup2(tdata->pool, &sdp->conn->addr, ast_sockaddr_stringify_host(&transport_state->external_media_address));
 		}

res/res_pjsip_t38.c

@@ -952,7 +952,7 @@ static void change_outgoing_sdp_stream_media_address(pjsip_tx_data *tdata, struc
 {
 	RAII_VAR(struct ast_sip_transport_state *, transport_state, ast_sip_get_transport_state(ast_sorcery_object_get_id(transport)), ao2_cleanup);
 	char host[NI_MAXHOST];
-	struct ast_sockaddr addr = { { 0, } };
+	struct ast_sockaddr our_sdp_addr = { { 0, } };
 
 	/* If the stream has been rejected there will be no connection line */
 	if (!stream->conn || !transport_state) {
@@ -960,10 +960,13 @@ static void change_outgoing_sdp_stream_media_address(pjsip_tx_data *tdata, struc
 	}
 
 	ast_copy_pj_str(host, &stream->conn->addr, sizeof(host));
-	ast_sockaddr_parse(&addr, host, PARSE_PORT_FORBID);
+	ast_sockaddr_parse(&our_sdp_addr, host, PARSE_PORT_FORBID);
 
-	/* Is the address within the SDP inside the same network? */
-	if (ast_sip_transport_is_local(transport_state, &addr)) {
+	/* Reversed check here. We don't check the remote endpoint being
+	 * in our local net, but whether our outgoing session IP is
+	 * local. If it is not, we won't do rewriting. No localnet
+	 * configured? Always rewrite. */
+	if (ast_sip_transport_is_nonlocal(transport_state, &our_sdp_addr) && transport_state->localnet) {
 		return;
 	}
 	ast_debug(5, "Setting media address to %s\n", ast_sockaddr_stringify_host(&transport_state->external_media_address));