Add IPv6 support (#349)

Adds IPv6 support.

FreeBSD users beware: From this point forward, you will have to set
`sysctl net.inet6.ip6.v6only=0` so that the BeamMP-Server continues to
work. The server also prints this information.

include/Client.h

@@ -88,7 +88,7 @@ public:
     void ClearCars();
     [[nodiscard]] int GetID() const { return mID; }
     [[nodiscard]] int GetUnicycleID() const { return mUnicycleID; }
-    [[nodiscard]] bool IsConnected() const { return mIsConnected; }
+    [[nodiscard]] bool IsUDPConnected() const { return mIsUDPConnected; }
     [[nodiscard]] bool IsSynced() const { return mIsSynced; }
     [[nodiscard]] bool IsSyncing() const { return mIsSyncing; }
     [[nodiscard]] bool IsGuest() const { return mIsGuest; }
@@ -100,7 +100,7 @@ public:
     [[nodiscard]] const std::queue<std::vector<uint8_t>>& MissedPacketQueue() const { return mPacketsSync; }
     [[nodiscard]] size_t MissedPacketQueueSize() const { return mPacketsSync.size(); }
     [[nodiscard]] std::mutex& MissedPacketQueueMutex() const { return mMissedPacketsMutex; }
-    void SetIsConnected(bool NewIsConnected) { mIsConnected = NewIsConnected; }
+    void SetIsUDPConnected(bool NewIsConnected) { mIsUDPConnected = NewIsConnected; }
     [[nodiscard]] TServer& Server() const;
     void UpdatePingTime();
     int SecondsSinceLastPing();
@@ -109,7 +109,7 @@ private:
     void InsertVehicle(int ID, const std::string& Data);
 
     TServer& mServer;
-    bool mIsConnected = false;
+    bool mIsUDPConnected = false;
     bool mIsSynced = false;
     bool mIsSyncing = false;
     mutable std::mutex mMissedPacketsMutex;

src/LuaAPI.cpp

@@ -298,7 +298,7 @@ void LuaAPI::MP::Sleep(size_t Ms) {
 bool LuaAPI::MP::IsPlayerConnected(int ID) {
     auto MaybeClient = GetClient(Engine->Server(), ID);
     if (MaybeClient && !MaybeClient.value().expired()) {
-        return MaybeClient.value().lock()->IsConnected();
+        return MaybeClient.value().lock()->IsUDPConnected();
     } else {
         return false;
     }

src/TConsole.cpp

@@ -543,7 +543,7 @@ void TConsole::Command_Status(const std::string&, const std::vector<std::string>
         if (!Client.expired()) {
             auto Locked = Client.lock();
             CarCount += Locked->GetCarCount();
-            ConnectedCount += Locked->IsConnected() ? 1 : 0;
+            ConnectedCount += Locked->IsUDPConnected() ? 1 : 0;
             GuestCount += Locked->IsGuest() ? 1 : 0;
             SyncedCount += Locked->IsSynced() ? 1 : 0;
             SyncingCount += Locked->IsSyncing() ? 1 : 0;

src/TNetwork.cpp

@@ -27,6 +27,8 @@
 #include <array>
 #include <boost/asio/ip/address.hpp>
 #include <boost/asio/ip/address_v4.hpp>
+#include <boost/asio/ip/address_v6.hpp>
+#include <boost/asio/ip/v6_only.hpp>
 #include <cstring>
 #include <zlib.h>
 
@@ -81,7 +83,8 @@ TNetwork::TNetwork(TServer& Server, TPPSMonitor& PPSMonitor, TResourceManager& R
 
 void TNetwork::UDPServerMain() {
     RegisterThread("UDPServer");
-    ip::udp::endpoint UdpListenEndpoint(ip::address::from_string("0.0.0.0"), Application::Settings.getAsInt(Settings::Key::General_Port));
+    // listen on all ipv6 addresses
+    ip::udp::endpoint UdpListenEndpoint(ip::address::from_string("::"), Application::Settings.getAsInt(Settings::Key::General_Port));
     boost::system::error_code ec;
     mUDPSock.open(UdpListenEndpoint.protocol(), ec);
     if (ec) {
@@ -89,6 +92,12 @@ void TNetwork::UDPServerMain() {
         std::this_thread::sleep_for(std::chrono::seconds(5));
         Application::GracefullyShutdown();
     }
+    // set IP_V6ONLY to false to allow both v4 and v6
+    boost::asio::ip::v6_only option(false);
+    mUDPSock.set_option(option, ec);
+    if (ec) {
+        beammp_warnf("Failed to unset IP_V6ONLY on UDP, only IPv6 will work: {}", ec.message());
+    }
     mUDPSock.bind(UdpListenEndpoint, ec);
     if (ec) {
         beammp_error("bind() failed: " + ec.message());
@@ -100,8 +109,8 @@ void TNetwork::UDPServerMain() {
         + std::to_string(Application::Settings.getAsInt(Settings::Key::General_MaxPlayers)) + (" Clients"));
     while (!Application::IsShuttingDown()) {
         try {
-            ip::udp::endpoint client {};
+            ip::udp::endpoint remote_client_ep {};
-            std::vector<uint8_t> Data = UDPRcvFromClient(client); // Receives any data from Socket
+            std::vector<uint8_t> Data = UDPRcvFromClient(remote_client_ep);
             auto Pos = std::find(Data.begin(), Data.end(), ':');
             if (Data.empty() || Pos > Data.begin() + 2)
                 continue;
@@ -117,16 +126,31 @@ void TNetwork::UDPServerMain() {
                 }
 
                 if (Client->GetID() == ID) {
-                    Client->SetUDPAddr(client);
+                    // not initialized yet
-                    Client->SetIsConnected(true);
+                    if (Client->GetUDPAddr() == ip::udp::endpoint {} || !Client->IsUDPConnected()) {
-                    Data.erase(Data.begin(), Data.begin() + 2);
+                        // same IP (just a sanity check)
-                    mServer.GlobalParser(ClientPtr, std::move(Data), mPPSMonitor, *this);
+                        if (remote_client_ep.address() == Client->GetTCPSock().remote_endpoint().address()) {
+                            Client->SetUDPAddr(remote_client_ep);
+                            Client->SetIsUDPConnected(true);
+                            beammp_debugf("UDP connected for client {}", ID);
+                        } else {
+                            beammp_debugf("Denied initial UDP packet due to IP mismatch");
+                            return false;
+                        }
+                    }
+                    if (Client->GetUDPAddr() == remote_client_ep) {
+                        Data.erase(Data.begin(), Data.begin() + 2);
+                        mServer.GlobalParser(ClientPtr, std::move(Data), mPPSMonitor, *this);
+                    } else {
+                        beammp_debugf("Ignored UDP packet due to remote address mismatch");
+                        return false;
+                    }
                 }
 
                 return true;
             });
         } catch (const std::exception& e) {
-            beammp_error(("fatal: ") + std::string(e.what()));
+            beammp_warnf("Failed to receive/parse packet via UDP: {}", e.what());
         }
     }
 }
@@ -134,7 +158,10 @@ void TNetwork::UDPServerMain() {
 void TNetwork::TCPServerMain() {
     RegisterThread("TCPServer");
 
-    ip::tcp::endpoint ListenEp(ip::address::from_string("0.0.0.0"), Application::Settings.getAsInt(Settings::Key::General_Port));
+    // listen on all ipv6 addresses
+    auto port = uint16_t(Application::Settings.getAsInt(Settings::Key::General_Port));
+    ip::tcp::endpoint ListenEp(ip::address::from_string("::"), port);
+    beammp_infof("Listening on 0.0.0.0:{0} and [::]:{0}", port);
     ip::tcp::socket Listener(mServer.IoCtx());
     boost::system::error_code ec;
     Listener.open(ListenEp.protocol(), ec);
@@ -142,6 +169,16 @@ void TNetwork::TCPServerMain() {
         beammp_errorf("Failed to open socket: {}", ec.message());
         return;
     }
+    // set IP_V6ONLY to false to allow both v4 and v6
+    boost::asio::ip::v6_only option(false);
+    Listener.set_option(option, ec);
+    if (ec) {
+        beammp_warnf("Failed to unset IP_V6ONLY on TCP, only IPv6 will work: {}", ec.message());
+    }
+#if defined(BEAMMP_FREEBSD)
+    beammp_warnf("WARNING: On FreeBSD, for IPv4 to work, you must run `sysctl net.inet6.ip6.v6only=0`!");
+    beammp_debugf("This is due to an annoying detail in the *BSDs: In the name of security, unsetting the IPV6_V6ONLY option does not work by default (but does not fail???), as it allows IPv4 mapped IPv6 like ::ffff:127.0.0.1, which they deem a security issue. For more information, see RFC 2553, section 3.7.");
+#endif
     socket_base::linger LingerOpt {};
     LingerOpt.enabled(false);
     Listener.set_option(LingerOpt, ec);
@@ -170,13 +207,13 @@ void TNetwork::TCPServerMain() {
             ip::tcp::endpoint ClientEp;
             ip::tcp::socket ClientSocket = Acceptor.accept(ClientEp, ec);
             if (ec) {
-                beammp_errorf("failed to accept: {}", ec.message());
+                beammp_errorf("Failed to accept() new client: {}", ec.message());
             }
             TConnection Conn { std::move(ClientSocket), ClientEp };
             std::thread ID(&TNetwork::Identify, this, std::move(Conn));
             ID.detach(); // TODO: Add to a queue and attempt to join periodically
         } catch (const std::exception& e) {
-            beammp_error("fatal: " + std::string(e.what()));
+            beammp_errorf("Exception in accept routine: {}", e.what());
         }
     } while (!Application::IsShuttingDown());
 }
@@ -257,8 +294,14 @@ std::string HashPassword(const std::string& str) {
 
 std::shared_ptr<TClient> TNetwork::Authentication(TConnection&& RawConnection) {
     auto Client = CreateClient(std::move(RawConnection.Socket));
-    Client->SetIdentifier("ip", RawConnection.SockAddr.address().to_string());
+    std::string ip = "";
-    beammp_tracef("This thread is ip {}", RawConnection.SockAddr.address().to_string());
+    if (RawConnection.SockAddr.address().to_v6().is_v4_mapped()) {
+        ip = boost::asio::ip::make_address_v4(ip::v4_mapped_t::v4_mapped, RawConnection.SockAddr.address().to_v6()).to_string();
+    } else {
+        ip = RawConnection.SockAddr.address().to_string();
+    }
+    Client->SetIdentifier("ip", ip);
+    beammp_tracef("This thread is ip {} ({})", ip, RawConnection.SockAddr.address().to_v6().is_v4_mapped() ? "IPv4 mapped IPv6" : "IPv6");
 
     beammp_info("Identifying new ClientConnection...");
 
@@ -978,7 +1021,7 @@ void TNetwork::SendToAll(TClient* c, const std::vector<uint8_t>& Data, bool Self
 }
 
 bool TNetwork::UDPSend(TClient& Client, std::vector<uint8_t> Data) {
-    if (!Client.IsConnected() || Client.IsDisconnected()) {
+    if (!Client.IsUDPConnected() || Client.IsDisconnected()) {
         // this can happen if we try to send a packet to a client that is either
         // 1. not yet fully connected, or
         // 2. disconnected and not yet fully removed