bugfix(network): Increase message buffer and max packet sizes to reduce connection issues (TheSuperHackers#2277)

Author: Mauller

Core/GameEngine/Include/Common/GameDefines.h

@@ -45,6 +45,11 @@
 #define RETAIL_COMPATIBLE_PATHFINDING_ALLOCATION (1)
 #endif
 
+// Disable non retail fixes in the networking, such as putting more data per UDP packet
+#ifndef RETAIL_COMPATIBLE_NETWORKING
+#define RETAIL_COMPATIBLE_NETWORKING (1)
+#endif
+
 // This is essentially synonymous for RETAIL_COMPATIBLE_CRC. There is a lot wrong with AIGroup, such as use-after-free, double-free, leaks,
 // but we cannot touch it much without breaking retail compatibility. Do not shy away from using massive hacks when fixing issues with AIGroup,
 // but put them behind this macro.

Core/GameEngine/Include/GameNetwork/LANAPI.h

@@ -44,7 +44,7 @@ static const Int g_lanHostNameLength = 1;
 static const Int g_lanGameNameLength = 16; // reduced length because of game option length
 static const Int g_lanGameNameReservedLength = 16; // save N wchars for ID info
 static const Int g_lanMaxChatLength = 100;
-static const Int m_lanMaxOptionsLength = MAX_PACKET_SIZE - ( 8 + (g_lanGameNameLength+1)*2 + 4 + (g_lanPlayerNameLength+1)*2
+static const Int m_lanMaxOptionsLength = MAX_LANAPI_PACKET_SIZE - ( 8 + (g_lanGameNameLength+1)*2 + 4 + (g_lanPlayerNameLength+1)*2
 																														+ (g_lanLoginNameLength+1) + (g_lanHostNameLength+1) );
 static const Int g_maxSerialLength = 23; // including the trailing '\0'
 
@@ -271,7 +271,7 @@ struct LANMessage
 };
 #pragma pack(pop)
 
-static_assert(sizeof(LANMessage) <= MAX_PACKET_SIZE, "LANMessage struct cannot be larger than the max packet size");
+static_assert(sizeof(LANMessage) <= MAX_LANAPI_PACKET_SIZE, "LANMessage struct cannot be larger than the max packet size");
 
 
 /**

Core/GameEngine/Include/GameNetwork/NetworkDefs.h

@@ -48,18 +48,35 @@ enum ConnectionNumbers CPP_11(: Int)
 	NUM_CONNECTIONS
 };
 
-static const Int MAX_SLOTS = MAX_PLAYER+1;
+static constexpr const Int MAX_SLOTS = MAX_PLAYER+1;
 
+// TheSuperHackers @info As we are not detecting for network fragmentation and dynamically adjusting payload sizes, we set an 1100 bytes UDP payload as a safe upper limit for various networks
+// We chose 1100 bytes as when taking mobile networks into account, maximum transmission unit sizes can vary from 1340 - 1500 bytes
+// and when the packet headers for PPPOE, IPV6 and other virtual network encapsulation are considered, we need a lower safe UDP payload to prevent fragmentation.
+static constexpr const Int MAX_UDP_PAYLOAD_SIZE = 1100;
 // UDP (8 bytes) + IP header (28 bytes) = 36 bytes total.  We want a total packet size of 512, so 512 - 36 = 476
-static const Int MAX_PACKET_SIZE = 476;
+static constexpr const Int RETAIL_GAME_PACKET_SIZE = 476;
+
+// TheSuperHackers @info The legacy lanapi cannot use a larger packet size without breaking the gameinfo command
+static constexpr const Int MAX_LANAPI_PACKET_SIZE = RETAIL_GAME_PACKET_SIZE;
+
+// TheSuperHackers @bugfix Mauller 08/02/2026 Allow larger ethernet UDP payload to be used for game messages, this fixes connection issues and eliminates disconnection bugs
+#if RETAIL_COMPATIBLE_NETWORKING
+static constexpr const Int MAX_PACKET_SIZE = RETAIL_GAME_PACKET_SIZE;
+static constexpr const Int MAX_NETWORK_MESSAGE_LEN = 1024;
+#else
+static constexpr const Int MAX_PACKET_SIZE = MAX_UDP_PAYLOAD_SIZE - sizeof(TransportMessageHeader);
+static constexpr const Int MAX_NETWORK_MESSAGE_LEN = MAX_UDP_PAYLOAD_SIZE;
+#endif
+
+// TheSuperHackers @bugfix Mauller 08/02/2026 Double send and receive buffer sizes to alleviate the occurance of disconnection issues in retail and non retail code.
+static constexpr const Int MAX_MESSAGES = 256;
 
 /**
  * Command packet - contains frame #, total # of commands, and each command.  This is what gets sent
  * to each player every frame
  */
-#define MAX_MESSAGE_LEN 1024
-#define MAX_MESSAGES 128
-static const Int numCommandsPerCommandPacket = (MAX_MESSAGE_LEN - sizeof(UnsignedInt) - sizeof(UnsignedShort))/sizeof(GameMessage);
+static const Int numCommandsPerCommandPacket = (MAX_NETWORK_MESSAGE_LEN - sizeof(UnsignedInt) - sizeof(UnsignedShort))/sizeof(GameMessage);
 #pragma pack(push, 1)
 struct CommandPacket
 {
@@ -89,7 +106,14 @@ struct TransportMessageHeader
 struct TransportMessage
 {
 	TransportMessageHeader header;
-	UnsignedByte data[MAX_MESSAGE_LEN];
+#if RETAIL_COMPATIBLE_NETWORKING
+	// TheSuperHackers @info This value is not the correct one that should be used here, it should have been max packet size
+	// The non retail max network message len takes the extra bytes of the network message header into account when handling UDP payload data
+	// In retail this only works since no data larger than the retail game packet size is put into a network message
+	UnsignedByte data[MAX_NETWORK_MESSAGE_LEN];
+#else
+	UnsignedByte data[MAX_PACKET_SIZE];
+#endif
 	Int length;
 	UnsignedInt addr;
 	UnsignedShort port;

Core/GameEngine/Source/GameNetwork/LANAPI.cpp

@@ -67,8 +67,8 @@ LANGame::LANGame( void )
 
 LANAPI::LANAPI( void ) : m_transport(nullptr)
 {
-	DEBUG_LOG(("LANAPI::LANAPI() - max game option size is %d, sizeof(LANMessage)=%d, MAX_PACKET_SIZE=%d",
-		m_lanMaxOptionsLength, sizeof(LANMessage), MAX_PACKET_SIZE));
+	DEBUG_LOG(("LANAPI::LANAPI() - max game option size is %d, sizeof(LANMessage)=%d, MAX_LANAPI_PACKET_SIZE=%d",
+		m_lanMaxOptionsLength, sizeof(LANMessage), MAX_LANAPI_PACKET_SIZE));
 
 	m_lastResendTime = 0;
 	//

Core/GameEngine/Source/GameNetwork/Network.cpp

@@ -74,7 +74,7 @@ struct ConnectionMessage
 {
 	Int id;
 	NetMessageFlags flags;
-	UnsignedByte data[MAX_MESSAGE_LEN];
+	UnsignedByte data[MAX_NETWORK_MESSAGE_LEN];
 	time_t lastSendTime;
 	Int retries;
 	Int length;

Core/GameEngine/Source/GameNetwork/Transport.cpp

@@ -217,6 +217,10 @@ Bool Transport::doSend() {
 		if (m_outBuffer[i].length != 0)
 		{
 			int bytesSent = 0;
+			// TheSuperHackers @info The handling of data sizing of the payload within a UDP packet is confusing due to the current networking implementation
+			// The max game packet size needs to be smaller than max udp payload by sizeof(TransportMessageHeader)
+			// But the max network message size needs to include the bytes of the transport message header and equal the max udp payload
+			// Therefore, transmitted data needs to add the extra bytes of the network header to the payloads length
 			int bytesToSend = m_outBuffer[i].length + sizeof(TransportMessageHeader);
 			// Send this message
 			if ((bytesSent = m_udpsock->Write((unsigned char *)(&m_outBuffer[i]), bytesToSend, m_outBuffer[i].addr, m_outBuffer[i].port)) > 0)
@@ -281,12 +285,15 @@ Bool Transport::doRecv()
 #if defined(RTS_DEBUG)
 	UnsignedInt now = timeGetTime();
 #endif
-
+	// TheSuperHackers @info The handling of data sizing of the payload within a UDP packet is confusing due to the current networking implementation
+	// The max game packet size needs to be smaller than max udp payload by sizeof(TransportMessageHeader)
+	// But the max network message size needs to include the bytes of the transport message header and equal the max udp payload
+	// Therefore, when receiving data we use the max udp payload size to receive the game packet payload and network header
 	TransportMessage incomingMessage;
 	unsigned char *buf = (unsigned char *)&incomingMessage;
-	int len = MAX_MESSAGE_LEN;
+	int len = MAX_NETWORK_MESSAGE_LEN;
 //	DEBUG_LOG(("Transport::doRecv - checking"));
-	while ( (len=m_udpsock->Read(buf, MAX_MESSAGE_LEN, &from)) > 0 )
+	while ( (len=m_udpsock->Read(buf, MAX_NETWORK_MESSAGE_LEN, &from)) > 0 )
 	{
 #if defined(RTS_DEBUG)
 		// Packet loss simulation
@@ -417,7 +424,7 @@ Bool Transport::isGeneralsPacket( TransportMessage *msg )
 	if (!msg)
 		return false;
 
-	if (msg->length < 0 || msg->length > MAX_MESSAGE_LEN)
+	if (msg->length < 0 || msg->length > MAX_NETWORK_MESSAGE_LEN)
 		return false;
 
 	CRC crc;