FIx missing ACK issue with webrtc gateway

[devopsec]

webrtc to SIP, and vice versa translation

[devopsec]

currently the hurdles to tackle are:

• asterisk SIP phone to external webrtc client the ACK is not forwarded to the SIP phone

[fatburger25]

Here is the fix,

@devopsec @mackhendricks

Please make changes to the existing kamailio config for the asterisk to accept the contact header format

Add the following code or replace the if (isbflagset(FLB_WS_DEVICE)) condition under INVITE route

			# Manipulate the WS Device header and send it to the PBX
                        $var(aor) = $fU;
                        $var(original_user) = $(ct{re.subst,/^<sip:([^@]+)@.*/\1/});
                        $var(host) = $(ct{re.subst,/^<*sip:.*@([^:;>]+).*$/\1/});

                        sql_query("kam", "SELECT received FROM location WHERE username='$var(aor)'", "ra");

                        if ($dbr(ra=>rows) > 0) {
                            $var(received) = $dbr(ra=>[0,0]);
                            xlog("L_WARN", "host ip is $var(host) Received value for $var(aor): $var(received)\n");
                        } else {
                            xlog("L_WARN", "No record found for $var(aor)\n");
                        }
                        sql_result_free("ra");

                        if (is_method("REGISTER")) {
                                if ($var(received) =~ "^sip:") {
                                    $var(received) = $(var(received){s.strip,4});
                                }
                                # Capture the original Contact header
                                $sht(original_contact=>$ci) = $ct;

                                $var(original_contact) = $ct;
                                append_hf("X-Original-Contact: $var(original_contact)\r\n");
                                xlog("L_WARN", "Original Contact: $ct for $ci \n");     

                                # Extract the domain and parameters from the original Contact
                                $var(domain_and_params) = $(ct{re.subst,/^<sip:[^@]+@([^>]+)>/\1/});

                                # Construct the new Contact header
                                $var(new_contact) = "<sip:" + $fU + "@" + $var(received) + ";x-ast-orig-host=" + $var(host) + ":0>";
                 
                                # Replace the Contact header
                                remove_hf("Contact");
                                append_hf("Contact: $var(new_contact)\r\n");
                                # Log the new Contact header
                                $var(via) = "SIP/2.0/WSS " + $var(host) + ";rport=" + $sp + ";received=" + $si + ";branch=" + $ci;
                                xlog("L_INFO", "New Contact: $var(new_contact)\n");
                        }
                        insert_hf("Koretel-VoIP: $si\r\n");
                        xlog("L_WARN", "Hitting Isravel Testing - This is a WS Device Orig Contact $var(orig) and source URI is $su and original user is $var(original_user) and Destination URI is $du Contact $ct and $fU $si:$sp\n");
                        add_path();
		}
		else {
			#Add the Path header for SIP UAC's - so that we know how to route back
			add_path_received($fU);
		}

Update the MANAGE_REPLY Route like below

onreply_route[MANAGE_REPLY] {
        # Rewrite the SDP on incoming replies of Websockets
        if (t_check_status("100|183|180|200") && has_body("application/sdp")) {
                $var(ru) = $sht(original_contact=>$ci);
                xlog("L_WARN", "new ru $var(ru) tu=$tu tU=$tU ru $ru du $du ct $ct Contact header transport=wss");
                if ($ct =~ ".*;transport=wss.*") {

                        $var(user) = $(ct{re.subst,/^<*sip:([^@]+)@.*$/\1/});
                        xlog("L_INFO", "User from Contact: $var(user)\n");

                        $var(aor) = $tU;
                        sql_query("kam", "SELECT received FROM location WHERE username='$var(aor)'", "ra");

                        if ($dbr(ra=>rows) > 0) {
                            $var(received) = $dbr(ra=>[0,0]);
                            xlog("L_WARN", "Received value for $var(aor): $var(received)\n");
                        } else {
                            xlog("L_WARN", "No record found for $var(aor)\n");
                        }
                        sql_result_free("ra");
                        if ($var(received) =~ "^sip:") {
                            $var(received) = $(var(received){s.strip,4});
                        }

                        # Capture the original Contact header
                        append_hf("X-Original-Contact: $var(ru)\r\n");
                        xlog("L_WARN", "Original Contact: $var(received) \n");

                        $var(new_contact) = "<sip:" + $var(user) + "@" + $var(received) + ">";

                        # Replace the Contact header
                        remove_hf("Contact");
                        append_hf("Contact: $var(new_contact)\r\n");

                        xlog("L_INFO", "New Contact: $var(new_contact) and Via $var(via)\n");
                        xlog("L_WARN", "Contact header contains transport=wss\n");
                } else {
                        xlog("L_WARN", "$ct Contact header does not contains transport=wss\n");
                }
	}

	xlog("L_DBG", "incoming reply from source address $si:$sp\n");

	# Rewrite the SDP on incoming replies
	if (t_check_status("183|180|200") && has_body("application/sdp")) {
		route(RTPENGINEANSWER);
		if ($avp(sdp_media_direction) != $null) {
			if (!msg_apply_changes()) {
				xlog("L_ERR", "could not update sdp\n");
			}
			if (!subst("/^a=(sendrecv|recvonly|sendonly|inactive).*/a=$avp(sdp_media_direction)/")) {
				#search_append_body("^a=.+", "a=$avp(sdp_media_direction)");
				xlog("L_ERR", "could not update sdp\n");
			}
			if (!msg_apply_changes()) {
				xlog("L_ERR", "could not update sdp\n");
			}
		}
		# TODO: why are we dropping 183 replies to MSTEAMS? - marked for review/validation
		if (t_check_status("183") && isbflagset(FLB_DST_MSTEAMS)) {
			drop();
		}
	}

Update the WS_REPLY route below

onreply_route[WS_REPLY] {

    # Reply to the WS REGISTER response - Send back the old Contact header back to the Server
    if (is_method("REGISTER") && status == 200) {
        # Retrieve the original Contact from the custom header
        $var(orig_contact) = $sht(original_contact=>$ci);

        if ($var(orig_contact) != $null) {
            # Modify the username in the original Contact
            $var(modified_contact) = $(var(orig_contact){re.subst,/^<sip:[^@]+/sip:$fU/});

            # Replace the Contact header in the response
            remove_hf("Contact");
            append_hf("Contact: $var(orig_contact)\r\n");

            xlog("L_INFO", "Modified 200 OK - Old Contact $var(orig_contact) and New Contact: $var(modified_contact)\n");

        } else {
            xlog("L_WARN", "X-Original-Contact header not found in response\n");
        }
    }

    if (nat_uac_test("64")) {
		# Do NAT traversal stuff for replies to a WebSocket connection
		# - even if it is not behind a NAT!
		# This won't be needed in the future if Kamailio and the
		# WebSocket client support Outbound and Path.
		add_contact_alias();
    }
}

[mackhendricks]

Thank you....we are reviewing this. We really appreicate