Remove INetSession

This was only used in the `CNetFileTransferer`. Only one function is
called. That can also be a `std::function`.

source/network/NetFileTransfer.cpp

@@ -1,4 +1,4 @@
-/* Copyright (C) 2025 Wildfire Games.
+/* Copyright (C) 2026 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -97,7 +97,7 @@ Status CNetFileTransferer::OnFileTransferData(const CFileTransferDataMessage& me
 	CFileTransferAckMessage ackMessage;
 	ackMessage.m_RequestID = message.m_RequestID;
 	ackMessage.m_NumPackets = 1; // TODO: would be nice to send a single ack for multiple packets at once
-	m_Session->SendMessage(&ackMessage);
+	m_SendMessage(&ackMessage);
 
 	if (task.buffer.size() == task.length)
 	{
@@ -155,7 +155,7 @@ void CNetFileTransferer::StartTask(RequestType requestType, std::function<void(s
 	CFileTransferRequestMessage request;
 	request.m_RequestType = static_cast<i8>(requestType);
 	request.m_RequestID = requestID;
-	m_Session->SendMessage(&request);
+	m_SendMessage(&request);
 }
 
 void CNetFileTransferer::StartResponse(u32 requestID, const std::string& data)
@@ -171,7 +171,7 @@ void CNetFileTransferer::StartResponse(u32 requestID, const std::string& data)
 	CFileTransferResponseMessage respMessage;
 	respMessage.m_RequestID = requestID;
 	respMessage.m_Length = task.buffer.size();
-	m_Session->SendMessage(&respMessage);
+	m_SendMessage(&respMessage);
 }
 
 void CNetFileTransferer::Poll()
@@ -190,7 +190,7 @@ void CNetFileTransferer::Poll()
 			dataMessage.m_Data = task.buffer.substr(task.offset, packetSize);
 			task.offset += packetSize;
 			++task.packetsInFlight;
-			m_Session->SendMessage(&dataMessage);
+			m_SendMessage(&dataMessage);
 		}
 	}
 

source/network/NetFileTransfer.h

@@ -1,4 +1,4 @@
-/* Copyright (C) 2025 Wildfire Games.
+/* Copyright (C) 2026 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -32,7 +32,6 @@ class CFileTransferAckMessage;
 class CFileTransferDataMessage;
 class CFileTransferResponseMessage;
 class CNetMessage;
-class INetSession;
 
 // Assume this is sufficiently less than MTU that packets won't get
 // fragmented or dropped.
@@ -59,8 +58,9 @@ public:
 		REJOIN
 	};
 
-	CNetFileTransferer(INetSession* session)
-		: m_Session(session), m_NextRequestID(1), m_LastProgressReportTime(0)
+	template<typename Session>
+	CNetFileTransferer(Session& session) :
+		m_SendMessage{std::bind_front(&Session::SendMessage, std::ref(session))}
 	{
 	}
 
@@ -107,9 +107,9 @@ private:
 		size_t packetsInFlight;
 	};
 
-	INetSession* m_Session;
+	std::function<bool(const CNetMessage* message)> m_SendMessage;
 
-	u32 m_NextRequestID;
+	u32 m_NextRequestID{1};
 
 
 	struct AsyncFileReceiveTask
@@ -132,7 +132,7 @@ private:
 	using FileSendTasksMap = std::map<u32, CNetFileSendTask>;
 	FileSendTasksMap m_FileSendTasks;
 
-	double m_LastProgressReportTime;
+	double m_LastProgressReportTime{0};
 };
 
 #endif // NETFILETRANSFER_H

source/network/NetSession.cpp

@@ -1,4 +1,4 @@
-/* Copyright (C) 2025 Wildfire Games.
+/* Copyright (C) 2026 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -36,7 +36,7 @@ constexpr int NETCLIENT_POLL_TIMEOUT = 50;
 constexpr int CHANNEL_COUNT = 1;
 
 CNetClientSession::CNetClientSession(CNetClient& client) :
-	m_Client(client), m_FileTransferer(this), m_Host(nullptr), m_Server(nullptr),
+	m_Client(client), m_FileTransferer(*this), m_Host(nullptr), m_Server(nullptr),
 	m_Stats(nullptr), m_IncomingMessages(16), m_OutgoingMessages(16),
 	m_LoopRunning(false), m_ShouldShutdown(false), m_MeanRTT(0), m_LastReceivedTime(0)
 {
@@ -239,7 +239,7 @@ u32 CNetClientSession::GetMeanRTT() const
 }
 
 CNetServerSession::CNetServerSession(CNetServerWorker& server, ENetPeer* peer) :
-	m_Server(server), m_FileTransferer(this), m_Peer(peer), m_HostID(0), m_GUID(), m_UserName()
+	m_Server(server), m_FileTransferer(*this), m_Peer(peer), m_HostID(0), m_GUID(), m_UserName()
 {
 }
 

source/network/NetSession.h

@@ -1,4 +1,4 @@
-/* Copyright (C) 2025 Wildfire Games.
+/* Copyright (C) 2026 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -50,22 +50,12 @@ typedef struct _ENetHost ENetHost;
  * A client runs one session at once; a server typically runs many.
  */
 
-/**
- * Interface for sessions to which messages can be sent.
- */
-class INetSession
-{
-public:
-	virtual ~INetSession() {}
-	virtual bool SendMessage(const CNetMessage* message) = 0;
-};
-
 /**
  * The client end of a network session.
  * Provides an abstraction of the network interface, allowing communication with the server.
  * The NetClientSession is threaded, so all calls to the public interface must be thread-safe.
  */
-class CNetClientSession : public INetSession
+class CNetClientSession
 {
 	NONCOPYABLE(CNetClientSession);
 
@@ -94,7 +84,7 @@ public:
 	/**
 	 * Queue up a message to send to the server on the next Loop() call.
 	 */
-	virtual bool SendMessage(const CNetMessage* message) override;
+	bool SendMessage(const CNetMessage* message);
 
 	/**
 	 * Number of milliseconds since the most recent packet of the server was received.
@@ -155,7 +145,7 @@ private:
  * Thread-safety:
  * - This is constructed and used by CNetServerWorker in the network server thread.
  */
-class CNetServerSession : public CFsm<CNetServerSession, CNetMessage*>, public INetSession
+class CNetServerSession : public CFsm<CNetServerSession, CNetMessage*>
 {
 	NONCOPYABLE(CNetServerSession);
 
@@ -203,7 +193,7 @@ public:
 	/**
 	 * Send a message to the client.
 	 */
-	virtual bool SendMessage(const CNetMessage* message);
+	bool SendMessage(const CNetMessage* message);
 
 	CNetFileTransferer& GetFileTransferer() { return m_FileTransferer; }
 

source/network/tests/test_FileTransfer.h

@@ -1,4 +1,4 @@
-/* Copyright (C) 2025 Wildfire Games.
+/* Copyright (C) 2026 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -32,11 +32,10 @@ namespace
 {
 constexpr const char* MESSAGECONTENT{"Some example message content"};
 
-class MessageQueues final : public INetSession
+class MessageQueues
 {
 public:
-	~MessageQueues() final = default;
-	bool SendMessage(const CNetMessage* message) final
+	bool SendMessage(const CNetMessage* message)
 	{
 		switch (message->GetType())
 		{
@@ -77,7 +76,7 @@ void CheckSizes(MessageQueues& queues, size_t requestSize, size_t responseSize,
 struct Participant
 {
 	MessageQueues queues;
-	CNetFileTransferer transferer{&queues};
+	CNetFileTransferer transferer{queues};
 };
 }