Hosting a game

Set up a server and wait for players to join

To host a multiplayer game, one player must set up a server that listens for incoming connections. The SetupHost() function handles all server initialization.

How hosting works

1. Configure the server address

   The server binds to all available network interfaces on the specified port:

   main.cpp

   ENetAddress address;
   address.host = ENET_HOST_ANY;
   address.port = SERVER_PORT;
   

   ENET_HOST_ANY allows the server to accept connections on any network interface.

2. Create the ENet host

   Create the server host with the following parameters:

   main.cpp

   serverHost = enet_host_create(
       &address,
       1, // max clients
       2, // max channels
       0, // incoming bandwidth (0 = unlimited)
       0  // outgoing bandwidth (0 = unlimited)
   );
   

   Parameters:

   • Max clients: 1 - Only one client can connect for 1v1 gameplay
   • Max channels: 2 - Two communication channels available
   • Bandwidth limits: 0 - No bandwidth restrictions
3. Verify host creation

   Check if the host was created successfully:

   main.cpp

   if (serverHost == NULL){
       printf("failed to create server host");
       return false;
   }
   printf("Server hosting on port %d\n" , SERVER_PORT);
   return true;
   

   If creation fails, the function returns false and the game returns to the main menu.

4. Wait for connections

   The game enters the HOSTING state and waits for a client to connect:

   main.cpp

   ENetEvent event;
   while (enet_host_service(serverHost, &event, 0) > 0) {
       if (event.type == ENET_EVENT_TYPE_CONNECT) {
           printf("Client connected!\n");
           clientPeer = event.peer;
           connectionState = "CONNECTED";
           
           // Start the game
           state = "MULTIPLAYER";
       }
   }
   

   Once a client connects, the game transitions to the multiplayer gameplay state.

Complete SetupHost function

main.cpp

bool SetupHost(){
    ENetAddress address;
    address.host = ENET_HOST_ANY;
    address.port = SERVER_PORT;
    // making the server host
    serverHost = enet_host_create(
        &address,
        1, // max clients
        2, // max channels
        0, // incoming bandwidth (0 = unlimited)
        0
    );
    if (serverHost == NULL){
        printf("failed to create server host");
        return false;
    }
    printf("Server hosting on port %d\n" , SERVER_PORT);
    return true;
}

Network variables

The following global variables manage the host connection:

main.cpp

ENetHost* serverHost = nullptr; // for host server
ENetPeer* clientPeer = nullptr; // for host connection to client

When hosting, the server uses serverHost to manage the connection and stores the connected client in clientPeer.

Troubleshooting

If the server fails to start, ensure:

• Port 7777 is not already in use by another application
• Firewall settings allow incoming connections on port 7777
• ENet has been properly initialized before calling SetupHost()