Bump version to 3.9.4

client -> server `t[8 bytes]`
server -> client `t[client's 8 bytes][server time 8 bytes]`

---

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generated or otherwise automatically generated may be rejected without
further discussion.
I declare that I fully understand all code I pushed into this PR, and
wrote all this code myself and own the rights to this code.

include/Common.h

@@ -129,7 +129,7 @@ private:
     static inline std::mutex mShutdownHandlersMutex {};
     static inline std::deque<TShutdownHandler> mShutdownHandlers {};
 
-    static inline Version mVersion { 3, 9, 3 };
+    static inline Version mVersion { 3, 9, 4 };
 };
 
 /// Used to static_assert in std::visit

include/Env.h

@@ -23,6 +23,7 @@
 namespace Env {
 
 enum class Key {
+    MAX_CONCURRENT_CONNECTIONS,
     // provider settings
     PROVIDER_UPDATE_MESSAGE,
     PROVIDER_DISABLE_CONFIG,

include/TServer.h

@@ -53,7 +53,10 @@ public:
 
     io_context& IoCtx() { return mIoCtxPoller.IoCtx(); }
 
+    uint64_t GetServerTimeMS() const { return std::chrono::duration_cast<std::chrono::milliseconds>(std::chrono::steady_clock::now() - TimeSyncStart).count();}
+    double GetServerTime() const { return std::chrono::duration<double>(std::chrono::steady_clock::now() - TimeSyncStart).count(); }
 private:
+    std::chrono::time_point<std::chrono::steady_clock> TimeSyncStart;
     TIoPollThread mIoCtxPoller;
     TClientSet mClients;
     mutable RWMutex mClientsMutex;

src/Env.cpp

@@ -45,6 +45,9 @@ std::string_view Env::ToString(Env::Key key) {
     case Key::PROVIDER_IP_ENV:
         return "BEAMMP_PROVIDER_IP_ENV";
         break;
+    case Key::MAX_CONCURRENT_CONNECTIONS:
+        return "BEAMMP_MAX_CONCURRENT_CONNECTIONS";
+        break;
     }
     return "";
 }

src/TLuaEngine.cpp

@@ -1012,6 +1012,14 @@ TLuaEngine::StateThreadData::StateThreadData(const std::string& Name, TLuaStateI
     }
     MPTable.set_function("Get", &LuaAPI::MP::Get);
 
+    MPTable.set_function("GetServerTimeMS", [this](const sol::this_state ts) {
+        return make_object(sol::state_view(ts), this->mEngine->Server().GetServerTimeMS());
+    });
+
+    MPTable.set_function("GetServerTime", [this](const sol::this_state ts) {
+        return make_object(sol::state_view(ts), this->mEngine->Server().GetServerTime());
+    });
+
     auto UtilTable = StateView.create_named_table("Util");
     UtilTable.set_function("LogDebug", [this](sol::variadic_args args) {
         std::string ToPrint = "";

src/TNetwork.cpp

@@ -19,6 +19,7 @@
 #include "TNetwork.h"
 #include "Client.h"
 #include "Common.h"
+#include "Env.h"
 #include "LuaAPI.h"
 #include "TConnectionLimiter.h"
 #include "THeartbeatThread.h"
@@ -45,8 +46,24 @@
 
 typedef boost::asio::detail::socket_option::integer<SOL_SOCKET, SO_RCVTIMEO> rcv_timeout_option;
 
-static constexpr uint8_t MAX_CONCURRENT_CONNECTIONS = 10;
 static constexpr uint8_t MAX_GLOBAL_CONNECTIONS = 128;
+static const uint8_t MAX_CONCURRENT_CONNECTIONS = []() -> uint8_t {
+    if (auto EnvVar = Env::Get(Env::Key::MAX_CONCURRENT_CONNECTIONS)) {
+        try {
+            beammp_debugf("BEAMMP_MAX_CONCURRENT_CONNECTIONS: {}", EnvVar.value());
+            if (const int value = std::stoi(std::string(EnvVar.value())); value > 0 && value <= MAX_GLOBAL_CONNECTIONS) {
+                beammp_debugf("BEAMMP_MAX_CONCURRENT_CONNECTIONS Parsed: {}", value);
+                return static_cast<uint8_t>(value);
+            }
+
+            beammp_warn("Env variable BEAMMP_MAX_CONCURRENT_CONNECTIONS is out of range, using default value.");
+        } catch (const std::exception&) {
+            beammp_warn("Error parsing Env variable BEAMMP_MAX_CONCURRENT_CONNECTIONS, using default value.");
+        }
+    }
+
+    return 10;
+}();
 static constexpr uint8_t READ_TIMEOUT_S = 10; // seconds
 
 std::vector<uint8_t> StringToVector(const std::string& Str) {

src/TServer.cpp

@@ -123,6 +123,12 @@ TEST_CASE("GetPidVid") {
 TServer::TServer(const std::vector<std::string_view>& Arguments) {
     beammp_info("BeamMP Server v" + Application::ServerVersionString());
     Application::SetSubsystemStatus("Server", Application::Status::Starting);
+    std::mt19937_64 TimeSyncRandomDevice(std::random_device{}());
+
+    TimeSyncStart = std::chrono::steady_clock::now()
+        - std::chrono::duration_cast<std::chrono::steady_clock::duration>(
+            std::chrono::duration<double>(std::uniform_real_distribution<double>(0.0, 2592000.0)(TimeSyncRandomDevice))
+        );
     Application::SetSubsystemStatus("Server", Application::Status::Good);
 }
 
@@ -210,6 +216,24 @@ void TServer::GlobalParser(const std::weak_ptr<TClient>& Client, std::vector<uin
         return;
     }
     switch (Code) {
+    case 't':
+        if (!udp && Packet.size() == 9) {
+            auto Time = GetServerTimeMS();
+
+            std::vector<uint8_t> ServerTime(sizeof(uint64_t));
+            std::memcpy(ServerTime.data(), &Time, sizeof(uint64_t));
+
+            auto Data = Packet;
+
+            beammp_debugf("Sending server time {} to client  '{}' ({}), client time: {}", Time, LockedClient->GetName(), LockedClient->GetID(), reinterpret_cast<uint64_t>(Data.data()));
+
+            Data.insert(Data.end(), ServerTime.begin(), ServerTime.end());
+
+            if (!Network.Respond(*LockedClient, Data, true)) {
+                Network.DisconnectClient(*LockedClient, "Failed to send time");
+            }
+        }
+        return;
     case 'H': // initial connection
         if (udp) {
             beammp_debugf("Received 'H' packet over UDP from client '{}' ({}), ignoring it", LockedClient->GetName(), LockedClient->GetID());