Network: Handle join request in Room

src/network/room.cpp

@@ -3,8 +3,11 @@
 // Refer to the license.txt file included.
 
 #include <atomic>
+#include <random>
 #include <thread>
+#include <vector>
 #include "enet/enet.h"
+#include "network/packet.h"
 #include "network/room.h"
 
 namespace Network {
@@ -14,17 +17,87 @@ static constexpr u32 MaxConcurrentConnections = 10;
 
 class Room::RoomImpl {
 public:
+    // This MAC address is used to generate a 'Nintendo' like Mac address.
+    const MacAddress NintendoOUI = {0x00, 0x1F, 0x32, 0x00, 0x00, 0x00};
+    std::mt19937 random_gen; ///< Random number generator. Used for GenerateMacAddress
+
     ENetHost* server = nullptr; ///< Network interface.
 
     std::atomic<State> state{State::Closed}; ///< Current state of the room.
     RoomInformation room_information;        ///< Information about this room.
 
+    struct Member {
+        std::string nickname;   ///< The nickname of the member.
+        std::string game_name;  ///< The current game of the member
+        MacAddress mac_address; ///< The assigned mac address of the member.
+        ENetPeer* peer;         ///< The remote peer.
+    };
+    using MemberList = std::vector<Member>;
+    MemberList members; ///< Information about the members of this room.
+
+    RoomImpl() : random_gen(std::random_device()()) {}
+
     /// Thread that receives and dispatches network packets
     std::unique_ptr<std::thread> room_thread;
 
     /// Thread function that will receive and dispatch messages until the room is destroyed.
     void ServerLoop();
     void StartLoop();
+
+    /**
+     * Parses and answers a room join request from a client.
+     * Validates the uniqueness of the username and assigns the MAC address
+     * that the client will use for the remainder of the connection.
+     */
+    void HandleJoinRequest(const ENetEvent* event);
+
+    /**
+     * Returns whether the nickname is valid, ie. isn't already taken by someone else in the room.
+     */
+    bool IsValidNickname(const std::string& nickname) const;
+
+    /**
+     * Returns whether the MAC address is valid, ie. isn't already taken by someone else in the
+     * room.
+     */
+    bool IsValidMacAddress(const MacAddress& address) const;
+
+    /**
+     * Sends a ID_ROOM_NAME_COLLISION message telling the client that the name is invalid.
+     */
+    void SendNameCollision(ENetPeer* client);
+
+    /**
+     * Sends a ID_ROOM_MAC_COLLISION message telling the client that the MAC is invalid.
+     */
+    void SendMacCollision(ENetPeer* client);
+
+    /**
+     * Notifies the member that its connection attempt was successful,
+     * and it is now part of the room.
+     */
+    void SendJoinSuccess(ENetPeer* client, MacAddress mac_address);
+
+    /**
+     * Sends the information about the room, along with the list of members
+     * to every connected client in the room.
+     * The packet has the structure:
+     * <MessageID>ID_ROOM_INFORMATION
+     * <String> room_name
+     * <uint32_t> member_slots: The max number of clients allowed in this room
+     * <uint32_t> num_members: the number of currently joined clients
+     * This is followed by the following three values for each member:
+     * <String> nickname of that member
+     * <MacAddress> mac_address of that member
+     * <String> game_name of that member
+     */
+    void BroadcastRoomInformation();
+
+    /**
+     * Generates a free MAC address to assign to a new client.
+     * The first 3 bytes are the NintendoOUI 0x00, 0x1F, 0x32
+     */
+    MacAddress GenerateMacAddress();
 };
 
 // RoomImpl
@@ -34,7 +107,12 @@ void Room::RoomImpl::ServerLoop() {
         if (enet_host_service(server, &event, 1000) > 0) {
             switch (event.type) {
             case ENET_EVENT_TYPE_RECEIVE:
-                // TODO(B3N30): Select the type of message and handle it
+                switch (event.packet->data[0]) {
+                case IdJoinRequest:
+                    HandleJoinRequest(&event);
+                    break;
+                    // TODO(B3N30): Handle the other message types
+                }
                 enet_packet_destroy(event.packet);
                 break;
             case ENET_EVENT_TYPE_DISCONNECT:
@@ -49,6 +127,126 @@ void Room::RoomImpl::StartLoop() {
     room_thread = std::make_unique<std::thread>(&Room::RoomImpl::ServerLoop, this);
 }
 
+void Room::RoomImpl::HandleJoinRequest(const ENetEvent* event) {
+    Packet packet;
+    packet.Append(event->packet->data, event->packet->dataLength);
+    packet.IgnoreBytes(sizeof(MessageID));
+    std::string nickname;
+    packet >> nickname;
+
+    MacAddress preferred_mac;
+    packet >> preferred_mac;
+
+    if (!IsValidNickname(nickname)) {
+        SendNameCollision(event->peer);
+        return;
+    }
+
+    if (preferred_mac != NoPreferredMac) {
+        // Verify if the preferred mac is available
+        if (!IsValidMacAddress(preferred_mac)) {
+            SendMacCollision(event->peer);
+            return;
+        }
+    } else {
+        // Assign a MAC address of this client automatically
+        preferred_mac = GenerateMacAddress();
+    }
+
+    // At this point the client is ready to be added to the room.
+    Member member{};
+    member.mac_address = preferred_mac;
+    member.nickname = nickname;
+    member.peer = event->peer;
+
+    members.push_back(member);
+
+    // Notify everyone that the room information has changed.
+    BroadcastRoomInformation();
+    SendJoinSuccess(event->peer, preferred_mac);
+}
+
+bool Room::RoomImpl::IsValidNickname(const std::string& nickname) const {
+    // A nickname is valid if it is not already taken by anybody else in the room.
+    // TODO(B3N30): Check for empty names, spaces, etc.
+    for (const Member& member : members) {
+        if (member.nickname == nickname) {
+            return false;
+        }
+    }
+    return true;
+}
+
+bool Room::RoomImpl::IsValidMacAddress(const MacAddress& address) const {
+    // A MAC address is valid if it is not already taken by anybody else in the room.
+    for (const Member& member : members) {
+        if (member.mac_address == address) {
+            return false;
+        }
+    }
+    return true;
+}
+
+void Room::RoomImpl::SendNameCollision(ENetPeer* client) {
+    Packet packet;
+    packet << static_cast<MessageID>(IdNameCollision);
+
+    ENetPacket* enet_packet =
+        enet_packet_create(packet.GetData(), packet.GetDataSize(), ENET_PACKET_FLAG_RELIABLE);
+    enet_peer_send(client, 0, enet_packet);
+    enet_host_flush(server);
+}
+
+void Room::RoomImpl::SendMacCollision(ENetPeer* client) {
+    Packet packet;
+    packet << static_cast<MessageID>(IdMacCollision);
+
+    ENetPacket* enet_packet =
+        enet_packet_create(packet.GetData(), packet.GetDataSize(), ENET_PACKET_FLAG_RELIABLE);
+    enet_peer_send(client, 0, enet_packet);
+    enet_host_flush(server);
+}
+
+void Room::RoomImpl::SendJoinSuccess(ENetPeer* client, MacAddress mac_address) {
+    Packet packet;
+    packet << static_cast<MessageID>(IdJoinSuccess);
+    packet << mac_address;
+    ENetPacket* enet_packet =
+        enet_packet_create(packet.GetData(), packet.GetDataSize(), ENET_PACKET_FLAG_RELIABLE);
+    enet_peer_send(client, 0, enet_packet);
+    enet_host_flush(server);
+}
+
+void Room::RoomImpl::BroadcastRoomInformation() {
+    Packet packet;
+    packet << static_cast<MessageID>(IdRoomInformation);
+    packet << room_information.name;
+    packet << room_information.member_slots;
+
+    packet << static_cast<uint32_t>(members.size());
+    for (const auto& member : members) {
+        packet << member.nickname;
+        packet << member.mac_address;
+        packet << member.game_name;
+    }
+
+    ENetPacket* enet_packet =
+        enet_packet_create(packet.GetData(), packet.GetDataSize(), ENET_PACKET_FLAG_RELIABLE);
+    enet_host_broadcast(server, 0, enet_packet);
+    enet_host_flush(server);
+}
+
+MacAddress Room::RoomImpl::GenerateMacAddress() {
+    MacAddress result_mac = NintendoOUI;
+    std::uniform_int_distribution<> dis(0x00, 0xFF); // Random byte between 0 and 0xFF
+    do {
+        for (int i = 3; i < result_mac.size(); ++i) {
+            result_mac[i] = dis(random_gen);
+        }
+    } while (!IsValidMacAddress(result_mac));
+    return result_mac;
+}
+
 // Room
 Room::Room() : room_impl{std::make_unique<RoomImpl>()} {}
 

src/network/room.h

@@ -4,6 +4,7 @@
 
 #pragma once
 
+#include <array>
 #include <memory>
 #include <string>
 #include "common/common_types.h"
@@ -18,6 +19,11 @@ struct RoomInformation {
     u32 member_slots; ///< Maximum number of members in this room
 };
 
+using MacAddress = std::array<uint8_t, 6>;
+/// A special MAC address that tells the room we're joining to assign us a MAC address
+/// automatically.
+const MacAddress NoPreferredMac = {0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF};
+
 // The different types of messages that can be sent. The first byte of each packet defines the type
 typedef uint8_t MessageID;
 enum RoomMessageTypes {