Commit unzipped original NetworkedTicTacToeStarter folder

Exercises/NetworkedTicTacToe/GameServer/GameServer.cpp

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+#include <SFML/Network.hpp>
+#include <algorithm>
+#include <cstring>
+#include <iostream>
+#include <mutex>
+#include <thread>
+#include <vector>
+
+// TODO: move `GameServer` into its own files (h/cpp).
+// Note: This is compiled with SFML 2.6.2 in mind.
+// It would work similarly with slightly older versions of SFML.
+// A thourough rework is necessary for SFML 3.0.
+
+enum GameMessageType : unsigned char {
+    JOIN_GAME = 0x01, PLACE_TOKEN = 0x02
+};
+
+enum Token : unsigned char {
+    NOUGHTS = 0x01, CROSSES = 0x02
+};
+
+class GameServer {
+public:
+    GameServer(unsigned short tcp_port) :
+        m_tcp_port(tcp_port) {}
+
+    // Binds to a port and then loops around.  For every client that connects,
+    // we start a new thread receiving their messages.
+    void tcp_start()
+    {
+        // BINDING
+        sf::TcpListener listener;
+        sf::Socket::Status status = listener.listen(m_tcp_port, sf::IpAddress("A.B.C.D"));
+        if (status != sf::Socket::Status::Done)
+        {
+            std::cerr << "Error binding listener to port" << std::endl;
+            return;
+        }
+
+        std::cout << "TCP Server is listening to port "
+           << m_tcp_port
+           << ", waiting for connections..."
+           << std::endl;
+
+        while (true)
+        {
+            // ACCEPTING
+            if(m_player_count < 2)
+            {
+                sf::TcpSocket* client = new sf::TcpSocket;
+                status = listener.accept(*client);
+                if (status != sf::Socket::Status::Done)
+                {
+                    delete client;
+                } else {
+                    {
+                        std::lock_guard<std::mutex> lock(m_clients_mutex);
+                        m_clients.push_back(client);
+                    }
+                    std::cout << "New client connected: "
+                        << client->getRemoteAddress()
+                        << std::endl;
+                    
+                    m_player_count++;
+
+                    std::thread(&GameServer::handle_client, this, client, m_player_count).detach();
+
+                    if(m_player_count == 2)
+                    {
+                        // --------------------------------------------------------------
+                        // Slight pause to ensure the all threads have started
+                        // --------------------------------------------------------------
+                        std::this_thread::sleep_for(std::chrono::milliseconds(250));
+                    }
+                }
+            }
+        }
+        // No need to call close of the listener.
+        // The connection is closed automatically when the listener object is out of scope.
+    }
+
+
+private:
+    unsigned short m_tcp_port;
+    unsigned short m_player_count { 0 };
+    
+    std::vector<sf::TcpSocket*> m_clients;
+    std::mutex m_clients_mutex;
+
+    // Loop around, receive messages from client and send them to all
+    // the other connected clients.
+    void handle_client(sf::TcpSocket* client, unsigned short player_num)
+    {
+        sf::Socket::Status status;
+
+        if(player_num == 1) {
+            std::cout << "Player " << player_num << " is NOUGHTS" << std::endl;
+            char buffer[2] = {
+                GameMessageType::JOIN_GAME,
+                Token::NOUGHTS
+            };
+        
+            status = client->send(buffer, message_size(GameMessageType::JOIN_GAME));
+
+            if (status != sf::Socket::Status::Done)
+            {
+                std::cerr << "Error sending JOIN_GAME to player 1" << std::endl;
+                return;
+            }
+        }
+        else if(player_num == 2) {
+            std::cout << "Player " << player_num << " is CROSSES" << std::endl;
+            char buffer[2] = {
+                GameMessageType::JOIN_GAME,
+                Token::CROSSES
+            };
+        
+            status = client->send(buffer, message_size(GameMessageType::JOIN_GAME));
+
+            if (status != sf::Socket::Status::Done)
+            {
+                std::cerr << "Error sending JOIN_GAME to player 2" << std::endl;
+                return;
+            }            
+        }
+        else {
+            return; // No more players please!!!
+        }
+        
+
+        while (true)
+        {
+            // RECEIVING
+            char payload[1024];
+            std::memset(payload, 0, 1024);
+            size_t received;
+            sf::Socket::Status status = client->receive(payload, 1024, received);
+            if (status != sf::Socket::Status::Done)
+            {
+                std::cerr << "Error receiving message from client" << std::endl;
+                break;
+            } else {
+                // Actually, there is no need to print the message if the message is not a string
+                debug_message(payload);
+
+                broadcast_message(payload, client);
+            }
+        }
+
+        // Everything that follows only makes sense if we have a graceful way to exiting the loop.
+        // Remove the client from the list when done
+        {
+            std::lock_guard<std::mutex> lock(m_clients_mutex);
+            m_clients.erase(std::remove(m_clients.begin(), m_clients.end(), client),
+                    m_clients.end());
+        }
+        delete client;
+    }
+
+    // Sends `message` from `sender` to all the other connected clients
+    bool broadcast_message(const char *buffer, sf::TcpSocket* sender)
+    {
+        size_t msgSize { message_size(buffer[0]) };
+
+        // You might want to validate the message before you send it.
+        // A few reasons for that:
+        // 1. Make sure the message makes sense in the game.
+        // 2. Make sure the sender is not cheating.
+        // 3. First need to synchronise the players inputs (usually done in Lockstep).
+        // 4. Compensate for latency and perform rollbacks (usually done in Ded Reckoning).
+        // 5. Delay the sending of messages to make the game fairer wrt high ping players.
+        // This is where you can write the authoritative part of the server.
+        std::lock_guard<std::mutex> lock(m_clients_mutex);
+        for (auto& client : m_clients)
+        {
+            if (client != sender)
+            {
+                // SENDING
+                sf::Socket::Status status = client->send(buffer, msgSize) ;
+                if (status != sf::Socket::Status::Done)
+                {
+                    std::cerr << "Error sending message to client" << std::endl;
+
+                    return false;
+                }
+            }
+        }
+
+        return true;
+    }
+
+    constexpr size_t message_size(const char messageType)
+    {
+        switch(messageType) {
+            case JOIN_GAME:     return 2;
+            case PLACE_TOKEN:   return sizeof(int) * 2 + 2;
+            default: return 0;
+        }
+    }
+
+    void debug_message(const char *buf)
+    {
+        const unsigned char msgType = buf[0];
+
+        switch(msgType) {
+            case JOIN_GAME: {
+                std::cout << "Player Joined The Game" << std::endl;
+                break;
+            }
+            case PLACE_TOKEN: {
+                const unsigned char *row { (unsigned char* )buf + 1 };
+                const unsigned char *col { (unsigned char* )buf + 1 + sizeof(int) };
+                unsigned int rowI = be32toh(*((unsigned int *) row));
+                unsigned int colI = be32toh(*((unsigned int *) col));
+                std::cout << "Player Placed A Token: (" << rowI << ", " << colI << ")" << std::endl;
+
+                break;
+            }
+        }
+    }
+};
+
+int main()
+{
+    GameServer server(4300);
+    
+    server.tcp_start();
+    
+    return 0;
+}

Exercises/NetworkedTicTacToe/GameServer/Makefile

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+SFML_PATH=/usr/local/Cellar/sfml/2.6.1/
+CXXFLAGS= -std=c++14 -Wall -Wpedantic -I${SFML_PATH}include/
+LDFLAGS=-L${SFML_PATH}lib/
+CFLAGS=-g -lsfml-graphics -lsfml-window -lsfml-system -lsfml-network -pthread
+CPPFLAGS=
+LDLIBS=
+LIBS=
+CPP=g++
+
+all: server
+
+server: GameServer.o
+	$(CPP) $(CXXFLAGS) $(LDFLAGS) $(LIBS) $^ -o $@ $(CFLAGS)
+
+clean:
+	\rm -f *.o server