Codechange: differentiate between UDP, TCP and compatibility MTU values

5 files changed, 10 insertions, 8 deletions

diff --git a/src/network/core/config.h b/src/network/core/config.h
index 1483419ea..572b4720d 100644
--- a/src/network/core/config.h
+++ b/src/network/core/config.h
@@ -30,7 +30,9 @@ static const uint16 NETWORK_DEFAULT_PORT          = 3979;         ///< The defau
 static const uint16 NETWORK_ADMIN_PORT            = 3977;         ///< The default port for admin network
 static const uint16 NETWORK_DEFAULT_DEBUGLOG_PORT = 3982;         ///< The default port debug-log is sent to (TCP)
 
-static const uint16 SEND_MTU                      = 1460;         ///< Number of bytes we can pack in a single packet
+static const uint16 UDP_MTU                       = 1460;         ///< Number of bytes we can pack in a single UDP packet
+static const uint16 TCP_MTU                       = 1460;         ///< Number of bytes we can pack in a single TCP packet
+static const uint16 COMPAT_MTU                    = 1460;         ///< Number of bytes we can pack in a single packet for backward compatibility
 
 static const byte NETWORK_GAME_ADMIN_VERSION      =    1;         ///< What version of the admin network do we use?
 static const byte NETWORK_GAME_INFO_VERSION       =    4;         ///< What version of game-info do we use?
@@ -46,14 +48,14 @@ static const uint NETWORK_PASSWORD_LENGTH         =   33;         ///< The maxim
 static const uint NETWORK_CLIENTS_LENGTH          =  200;         ///< The maximum length for the list of clients that controls a company, in bytes including '\0'
 static const uint NETWORK_CLIENT_NAME_LENGTH      =   25;         ///< The maximum length of a client's name, in bytes including '\0'
 static const uint NETWORK_RCONCOMMAND_LENGTH      =  500;         ///< The maximum length of a rconsole command, in bytes including '\0'
-static const uint NETWORK_GAMESCRIPT_JSON_LENGTH  = SEND_MTU - 3; ///< The maximum length of a gamescript json string, in bytes including '\0'. Must not be longer than SEND_MTU including header (3 bytes)
+static const uint NETWORK_GAMESCRIPT_JSON_LENGTH  = COMPAT_MTU-3; ///< The maximum length of a gamescript json string, in bytes including '\0'. Must not be longer than COMPAT_MTU including header (3 bytes)
 static const uint NETWORK_CHAT_LENGTH             =  900;         ///< The maximum length of a chat message, in bytes including '\0'
 
 static const uint NETWORK_GRF_NAME_LENGTH         =   80;         ///< Maximum length of the name of a GRF
 
 /**
  * Maximum number of GRFs that can be sent.
- * This limit is reached when PACKET_UDP_SERVER_RESPONSE reaches the maximum size of SEND_MTU bytes.
+ * This limit is reached when PACKET_UDP_SERVER_RESPONSE reaches the maximum size of UDP_MTU bytes.
  */
 static const uint NETWORK_MAX_GRF_COUNT           =   62;
 
diff --git a/src/network/core/packet.cpp b/src/network/core/packet.cpp
index 39531c0a4..40e664055 100644
--- a/src/network/core/packet.cpp
+++ b/src/network/core/packet.cpp
@@ -39,7 +39,7 @@ Packet::Packet(NetworkSocketHandler *cs, size_t limit, size_t initial_read_size)
 /**
  * Creates a packet to send
  * @param type  The type of the packet to send
- * @param limit The maximum number of bytes the packet may have. Default is SEND_MTU.
+ * @param limit The maximum number of bytes the packet may have. Default is COMPAT_MTU.
  *              Be careful of compatibility with older clients/servers when changing
  *              the limit as it might break things if the other side is not expecting
  *              much larger packets than what they support.
diff --git a/src/network/core/packet.h b/src/network/core/packet.h
index db051005c..d55dad316 100644
--- a/src/network/core/packet.h
+++ b/src/network/core/packet.h
@@ -56,7 +56,7 @@ private:
 
 public:
 	Packet(NetworkSocketHandler *cs, size_t limit, size_t initial_read_size = sizeof(PacketSize));
-	Packet(PacketType type, size_t limit = SEND_MTU);
+	Packet(PacketType type, size_t limit = COMPAT_MTU);
 
 	static void AddToQueue(Packet **queue, Packet *packet);
 	static Packet *PopFromQueue(Packet **queue);
diff --git a/src/network/core/tcp.cpp b/src/network/core/tcp.cpp
index be70efdd2..72e66a0b5 100644
--- a/src/network/core/tcp.cpp
+++ b/src/network/core/tcp.cpp
@@ -126,7 +126,7 @@ Packet *NetworkTCPSocketHandler::ReceivePacket()
 	if (!this->IsConnected()) return nullptr;
 
 	if (this->packet_recv == nullptr) {
-		this->packet_recv = new Packet(this, SEND_MTU);
+		this->packet_recv = new Packet(this, TCP_MTU);
 	}
 
 	Packet *p = this->packet_recv;
diff --git a/src/network/core/udp.cpp b/src/network/core/udp.cpp
index 8872fa295..e8299f7b6 100644
--- a/src/network/core/udp.cpp
+++ b/src/network/core/udp.cpp
@@ -119,8 +119,8 @@ void NetworkUDPSocketHandler::ReceivePackets()
 			struct sockaddr_storage client_addr;
 			memset(&client_addr, 0, sizeof(client_addr));
 
-			/* The limit is SEND_MTU, but also allocate that much as we need to read the whole packet in one go. */
-			Packet p(this, SEND_MTU, SEND_MTU);
+			/* The limit is UDP_MTU, but also allocate that much as we need to read the whole packet in one go. */
+			Packet p(this, UDP_MTU, UDP_MTU);
 			socklen_t client_len = sizeof(client_addr);
 
 			/* Try to receive anything */