AM2R-Multitroid/scripts/nat_handle_tcp_message.gml

/// nat_handle_tcp_message(message_map)
// Handles incoming TCP messages from mediation server
// message_map: ds_map returned from json_parse_nat_message()
// Call this from Async Networking event

var msg = argument0;

if (!ds_exists(msg, ds_type_map)) {
    exit;
}

var msg_id = ds_map_find_value(msg, "ID");
if (is_undefined(msg_id)) {
    exit;
}

switch (msg_id) {
    case MSG_CONNECTED:
        // Connected to mediation server - start NAT detection
        mediation_connected = true;
        nat_state = NAT_STATE_NAT_DETECTING;

        // Send NAT type request
        var params = ds_map_create();
        ds_map_add(params, "LocalPort", nat_local_port);
        ds_map_add(params, "ClientID", nat_client_id);
        nat_send_tcp_message(mediation_socket, MSG_NAT_TYPE_REQUEST, params);
        ds_map_destroy(params);
        break;

    case MSG_NAT_TEST_BEGIN:
        // Mediation server wants us to send UDP to test ports
        var test_port_one = ds_map_find_value(msg, "NATTestPortOne");
        var test_port_two = ds_map_find_value(msg, "NATTestPortTwo");

        if (!is_undefined(test_port_one) && !is_undefined(test_port_two)) {
            // Send NAT test packets to both ports
            var test_params = ds_map_create();
            ds_map_add(test_params, "ClientID", nat_client_id);
            var test_json = json_encode_nat_message(MSG_NAT_TEST, test_params);
            ds_map_destroy(test_params);

            var test_buf = buffer_create(string_length(test_json) + 1, buffer_fixed, 1);
            buffer_seek(test_buf, buffer_seek_start, 0);
            buffer_write(test_buf, buffer_text, test_json);

            network_send_udp_raw(socket, mediation_server_ip, test_port_one, test_buf, buffer_tell(test_buf));
            network_send_udp_raw(socket, mediation_server_ip, test_port_two, test_buf, buffer_tell(test_buf));

            buffer_delete(test_buf);
        }
        break;

    case MSG_NAT_TYPE_RESPONSE:
        // Received NAT type from server
        nat_type = ds_map_find_value(msg, "NATType");

        if (!is_undefined(nat_type)) {
            nat_state = NAT_STATE_WAITING;

            var type_name = "Unknown";
            if (nat_type == NAT_TYPE_DIRECT_MAPPING) type_name = "Direct Mapping (Full Cone)";
            else if (nat_type == NAT_TYPE_RESTRICTED) type_name = "Restricted";
            else if (nat_type == NAT_TYPE_SYMMETRIC) type_name = "Symmetric";

            // Now request connection to the game server
            nat_request_connection();
        }
        break;

    case MSG_CONNECTION_BEGIN:
        // Mediation server is coordinating connection - start hole punching
        var endpoint_str = ds_map_find_value(msg, "EndpointString");
        var peer_nat = ds_map_find_value(msg, "NATType");
        var conn_id = ds_map_find_value(msg, "ConnectionID");

        if (!is_undefined(endpoint_str) && !is_undefined(peer_nat)) {
            // Parse endpoint "ip:port"
            var colon_pos = string_pos(":", endpoint_str);
            if (colon_pos > 0) {
                nat_peer_ip = string_copy(endpoint_str, 1, colon_pos - 1);
                nat_peer_port = real(string_copy(endpoint_str, colon_pos + 1, string_length(endpoint_str) - colon_pos));
                nat_peer_nat_type = peer_nat;
                nat_connection_id = conn_id;

                // Check for unsupported Symmetric-to-Symmetric
                if (nat_type == NAT_TYPE_SYMMETRIC && nat_peer_nat_type == NAT_TYPE_SYMMETRIC) {
                    show_message("Connection not possible - both sides have Symmetric NAT");
                    nat_state = NAT_STATE_ERROR;
                    exit;
                }

                // Start hole punching
                nat_state = NAT_STATE_PUNCHING;
                nat_hole_punch_timer = 0;
                nat_hole_punch_count = 0;
                nat_hole_punch_received = 0;
            }
        }
        break;

    case MSG_CONNECTION_COMPLETE:
        // Connection established!
        nat_state = NAT_STATE_CONNECTED;

        // Update oClient to use the discovered endpoint
        server_ip = nat_peer_ip;
        server_port = nat_peer_port;

        // Mark as connected so game protocol can start
        isConnected = 1;
        connected = true;  // Mark as connected to prevent duplicate connection flow in Step event

        popup_text("Connected to server!");

        // Send initial connection packet to server
        buffer_delete(buffer);
        var size, type, alignment;
        size = 1024;
        type = buffer_grow;
        alignment = 1;
        buffer = buffer_create(size, type, alignment);
        buffer_seek(buffer, buffer_seek_start, 0);
        buffer_write(buffer, buffer_u8, 1);
        buffer_write(buffer, buffer_string, name + "," + global.multitroid_version);
        buffer_write(buffer, buffer_u8, global.sax);
        var bufferSize = buffer_tell(buffer);
        buffer_seek(buffer, buffer_seek_start, 0);
        buffer_write(buffer, buffer_s32, bufferSize);
        buffer_write(buffer, buffer_u8, 1);
        buffer_write(buffer, buffer_string, name + "," + global.multitroid_version);
        buffer_write(buffer, buffer_u8, global.sax);
        network_send_udp(socket, server_ip, server_port, buffer, buffer_tell(buffer));

        // Create nametag instance
        instance_create(x, y, oNametag);

        // Disconnect from mediation server - we don't need it anymore
        if (mediation_socket != -1) {
            network_destroy(mediation_socket);
            mediation_socket = -1;
            mediation_connected = false;
        }
        break;

    case MSG_SERVER_NOT_AVAILABLE:
        show_message("Server not available");
        nat_state = NAT_STATE_ERROR;
        break;

    case MSG_CONNECTION_TIMEOUT:
        show_message("Connection timeout");
        nat_state = NAT_STATE_ERROR;
        break;
}