Fix an issue where media would not flow for situations where the legacy STUN code is in use.

The STUN packets should *not* be blocked by strict RTP.

(closes issue ASTERISK-20102)
Reported by: Malcolm Davenport


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@369817 65c4cc65-6c06-0410-ace0-fbb531ad65f3

res/res_rtp_asterisk.c

@@ -2820,6 +2820,33 @@ static struct ast_frame *ast_rtp_read(struct ast_rtp_instance *instance, int rtc
 		return &ast_null_frame;
 	}
 
+	/* Get fields and verify this is an RTP packet */
+	seqno = ntohl(rtpheader[0]);
+
+	ast_rtp_instance_get_remote_address(instance, &remote_address);
+
+	if (!(version = (seqno & 0xC0000000) >> 30)) {
+		struct sockaddr_in addr_tmp;
+		struct ast_sockaddr addr_v4;
+		if (ast_sockaddr_is_ipv4(&addr)) {
+			ast_sockaddr_to_sin(&addr, &addr_tmp);
+		} else if (ast_sockaddr_ipv4_mapped(&addr, &addr_v4)) {
+			ast_debug(1, "Using IPv6 mapped address %s for STUN\n",
+				  ast_sockaddr_stringify(&addr));
+			ast_sockaddr_to_sin(&addr_v4, &addr_tmp);
+		} else {
+			ast_debug(1, "Cannot do STUN for non IPv4 address %s\n",
+				  ast_sockaddr_stringify(&addr));
+			return &ast_null_frame;
+		}
+		if ((ast_stun_handle_packet(rtp->s, &addr_tmp, rtp->rawdata + AST_FRIENDLY_OFFSET, res, NULL, NULL) == AST_STUN_ACCEPT) &&
+		    ast_sockaddr_isnull(&remote_address)) {
+			ast_sockaddr_from_sin(&addr, &addr_tmp);
+			ast_rtp_instance_set_remote_address(instance, &addr);
+		}
+		return &ast_null_frame;
+	}
+
 	/* If strict RTP protection is enabled see if we need to learn the remote address or if we need to drop the packet */
 	if (rtp->strict_rtp_state == STRICT_RTP_LEARN) {
 		ast_debug(1, "%p -- start learning mode pass with addr = %s\n", rtp, ast_sockaddr_stringify(&addr));
@@ -2853,33 +2880,6 @@ static struct ast_frame *ast_rtp_read(struct ast_rtp_instance *instance, int rtc
 		}
 	}
 
-	/* Get fields and verify this is an RTP packet */
-	seqno = ntohl(rtpheader[0]);
-
-	ast_rtp_instance_get_remote_address(instance, &remote_address);
-
-	if (!(version = (seqno & 0xC0000000) >> 30)) {
-		struct sockaddr_in addr_tmp;
-		struct ast_sockaddr addr_v4;
-		if (ast_sockaddr_is_ipv4(&addr)) {
-			ast_sockaddr_to_sin(&addr, &addr_tmp);
-		} else if (ast_sockaddr_ipv4_mapped(&addr, &addr_v4)) {
-			ast_debug(1, "Using IPv6 mapped address %s for STUN\n",
-				  ast_sockaddr_stringify(&addr));
-			ast_sockaddr_to_sin(&addr_v4, &addr_tmp);
-		} else {
-			ast_debug(1, "Cannot do STUN for non IPv4 address %s\n",
-				  ast_sockaddr_stringify(&addr));
-			return &ast_null_frame;
-		}
-		if ((ast_stun_handle_packet(rtp->s, &addr_tmp, rtp->rawdata + AST_FRIENDLY_OFFSET, res, NULL, NULL) == AST_STUN_ACCEPT) &&
-		    ast_sockaddr_isnull(&remote_address)) {
-			ast_sockaddr_from_sin(&addr, &addr_tmp);
-			ast_rtp_instance_set_remote_address(instance, &addr);
-		}
-		return &ast_null_frame;
-	}
-
 	/* If symmetric RTP is enabled see if the remote side is not what we expected and change where we are sending audio */
 	if (ast_rtp_instance_get_prop(instance, AST_RTP_PROPERTY_NAT)) {
 		if (ast_sockaddr_cmp(&remote_address, &addr)) {