Database connection parameters

    if (!t_check_trans()) {
        xlog("L_INFO", "No transaction found with t_check_trans(), trying t_lookup_cancel()\n");
        # Try to find the transaction using branch and Call-ID
        $var(branch) = $(hdr(Via){param.value,branch});
        if (!t_lookup_cancel()) {
            xlog("L_WARN", "No transaction found for CANCEL - $ci with branch $var(branch)\n");
            sl_reply("481", "Call Leg/Transaction Does Not Exist");
            exit;
        }
        xlog("L_INFO", "Found transaction using t_lookup_cancel()\n");
    }

    # Extract destination from original request
    if ($ru != "") {
        $du = $ru;
        xlog("L_INFO", "Setting destination from R-URI: $du\n");
    } else {
        xlog("L_WARN", "No R-URI found for CANCEL\n");
    }
    
    # Add debugging
    xlog("L_INFO", "Forwarding CANCEL to $du for call $ci\n");
    
    if (ds_is_from_list()) {
        ds_load_unset();
        xlog("L_INFO", "Unset dispatcher load for destination\n");
    }

    # Handle the client ID and call counting
    if (is_present_hf("X-VICIdial-Client-Id")) {
        $var(client_id) = $(hdr(X-VICIdial-Client-Id));
        if ($var(client_id) =~ "^(CID_[0-9]+)-[a-z]$") {
            $var(parent_id) = $(var(client_id){re.subst,/^(CID_[0-9]+)-[a-z]$/\1/});
        } else {
            $var(parent_id) = $var(client_id);
        }

        if($var(parent_id) != $null) {
            lock("calls_$var(parent_id)");
            if($sht(clientCalls=>$var(parent_id)) > 0) {
                $sht(clientCalls=>$var(parent_id)) = $sht(clientCalls=>$var(parent_id)) - 1;
                xlog("L_INFO", "CANCEL: Decremented call count for $var(parent_id) to $sht(clientCalls=>$var(parent_id))\n");
            }
            unlock("calls_$var(parent_id)");
        }
    }

    # Send 200 OK response for the CANCEL
    t_reply("200", "OK");
    
    # Force the relay of CANCEL to the destination
    t_relay();
    exit;
}

if(is_method("BYE")) {
    if((!allow_source_address("1") && !ds_is_from_list())) {
        xlog("L_WARN", "IP $si:$sp not in address or dispatcher list\n");
        sl_send_reply("403", "IP Not Allowed");
        exit;
    }
    route(RELAY);
    exit;
}
if (!allow_source_address("1") ) {
    xlog("L_WARN", "IP $si:$sp not allowed\n");
    sl_send_reply("403", "IP Not Allowed");
    exit;
}
if (is_method("ACK")) {
    if (t_check_trans()) {
        t_relay();
    } else {
        route(RELAY);
    }
    exit;
}
if (is_method("OPTIONS")) {
    options_reply();
    exit;
}

if (!mf_process_maxfwd_header("10")) {
    sl_send_reply("483", "Too Many Hops");
    exit;
}

if (is_method("INVITE")) {
    if (!is_present_hf("X-VICIdial-Client-Id")) {
        xlog("L_WARN", "INVITE received without X-VICIdial-Client-Id header\n");
        sl_send_reply("400", "Bad Request - Missing Client ID");
        exit;
    }

    t_check_trans();
    $var(client_id) = $(hdr(X-VICIdial-Client-Id));

    if ($var(client_id) =~ "^(CID_[0-9]+)-[a-z]$") {
        $var(parent_id) = $(var(client_id){re.subst,/^(CID_[0-9]+)-[a-z]$/\1/});
    } else {
        $var(parent_id) = $var(client_id);
    }
    $var(limit) = $sht(clientLimits=>$var(parent_id));
    if(!$var(limit)) {
        xlog("L_WARN", "No limit configured for client $var(parent_id)\n");
        sl_send_reply("403", "Client Not Configured");
        exit;
    }
    lock("calls_$var(parent_id)");
    $var(current_calls) = $sht(clientCalls=>$var(parent_id));
    if(!$var(current_calls)) {
        $var(current_calls) = 0;
    }
    if($var(current_calls) >= $var(limit)) {
        unlock("calls_$var(parent_id)");
        xlog("L_WARN", "Call limit exceeded for client $var(parent_id): $var(current_calls)/$var(limit)\n");
        sl_send_reply("429", "Concurrent Call Limit Exceeded");
        exit;
    }
    $sht(clientCalls=>$var(parent_id)) = $var(current_calls) + 1;
    unlock("calls_$var(parent_id)");
    route(GENERATE_SERIAL_NUMBER);
    # xlog("L_INFO", "Processing INVITE - checking load - Serial Number: $avp(serial_number)\n");
    $var(original_contact) = $ct;
    append_hf("X-Original-Contact: $var(original_contact)\r\n");
    append_hf("X-Original-IP: $si\r\n");
    append_hf("X-Original-Port: $sp\r\n");
    append_hf("X-Serial-Number: $avp(serial_number)\r\n");

    if (!ds_select_dst("4", "10")) {
        xlog("L_WARN", "All destinations at max load, forwarding to dump server\n");
        $du = "sip::5060";
        record_route();
        route(RELAY);
        exit;
    }

    xlog("L_INFO", "Selected destination: $du\n");
    record_route();
    ds_load_update();
    t_on_failure("MANAGE_FAILURE");
    route(RELAY);
    exit;
}

if (is_method("BYE")) {
    t_check_trans();
    if($sht(clientCalls=>$var(parent_id)) > 0) {
        $sht(clientCalls=>$var(parent_id)) = $sht(clientCalls=>$var(parent_id)) - 1;
    }
    if (ds_is_from_list()) {
        ds_load_unset();
    }
    route(RELAY);
    exit;
}

route(RELAY);

Database connection parameters

Configure hash tables

Transaction Module Parameters

Timer for refreshing limits