3 files changed, 1027 insertions, 0 deletions

diff --git a/src/OSSupport/CMakeLists.txt b/src/OSSupport/CMakeLists.txt
index e943ceb18..8454279fe 100644
--- a/src/OSSupport/CMakeLists.txt
+++ b/src/OSSupport/CMakeLists.txt
@@ -12,6 +12,7 @@ SET (SRCS
 	GZipFile.cpp
 	IsThread.cpp
 	ListenThread.cpp
+	Network.cpp
 	Semaphore.cpp
 	Socket.cpp
 	SocketThreads.cpp
@@ -26,6 +27,7 @@ SET (HDRS
 	GZipFile.h
 	IsThread.h
 	ListenThread.h
+	Network.h
 	Queue.h
 	Semaphore.h
 	Socket.h
diff --git a/src/OSSupport/Network.cpp b/src/OSSupport/Network.cpp
new file mode 100644
index 000000000..d947bfa90
--- /dev/null
+++ b/src/OSSupport/Network.cpp
@@ -0,0 +1,837 @@
+
+// Network.cpp
+
+// Implements the classes used for the Network API
+
+#include "Globals.h"
+#include "Network.h"
+#include <event2/event.h>
+#include <event2/thread.h>
+#include <event2/bufferevent.h>
+#include <event2/dns.h>
+
+
+
+
+
+////////////////////////////////////////////////////////////////////////////////
+// Self-test:
+
+class cNetworkTest
+{
+public:
+	/** cTCPLink callbacks that dump everything it received to the log. */
+	class cDumpCallbacks:
+		public cTCPLink::cCallbacks
+	{
+		cEvent & m_Event;
+
+		virtual void OnReceivedData(cTCPLink & a_Link, const char * a_Data, size_t a_Size) override
+		{
+			// Log the incoming data size:
+			AString Hex;
+			CreateHexDump(Hex, a_Data, a_Size, 16);
+			LOGD("Incoming data: %u bytes:\n%s", static_cast<unsigned>(a_Size), Hex.c_str());
+		}
+
+		virtual void OnRemoteClosed(cTCPLink & a_Link) override
+		{
+			LOGD("Remote has closed the connection.");
+			m_Event.Set();
+		}
+
+		virtual void OnError(cTCPLink & a_Link, int a_ErrorCode) override
+		{
+			LOGD("Error in the cDumpCallbacks.");
+			m_Event.Set();
+		}
+
+	public:
+		cDumpCallbacks(cEvent & a_Event):
+			m_Event(a_Event)
+		{
+		}
+	};
+
+
+	/** cTCPLink callbacks that echo everything they receive back to the remote peer. */
+	class cEchoCallbacks:
+		public cTCPLink::cCallbacks
+	{
+		cEvent & m_Event;
+
+		virtual void OnReceivedData(cTCPLink & a_Link, const char * a_Data, size_t a_Size) override
+		{
+			// Echo the incoming data back to outgoing data:
+			LOGD("Data received (%u bytes), echoing back.", static_cast<unsigned>(a_Size));
+			a_Link.Send(a_Data, a_Size);
+			LOGD("Echo queued");
+		}
+
+		virtual void OnRemoteClosed(cTCPLink & a_Link) override
+		{
+			LOGD("Remote has closed the connection.");
+			m_Event.Set();
+		}
+
+		virtual void OnError(cTCPLink & a_Link, int a_ErrorCode) override
+		{
+			LOGD("Error in the cEchoCallbacks.");
+			m_Event.Set();
+		}
+
+	public:
+		cEchoCallbacks(cEvent & a_Event):
+			m_Event(a_Event)
+		{
+		}
+	};
+
+
+	/** Connect callbacks that send a simple test message when connected. */
+	class cConnectCallbacks:
+		public cNetwork::cConnectCallbacks
+	{
+		cEvent & m_Event;
+
+		virtual void OnSuccess(cTCPLink & a_Link) override
+		{
+			LOGD("Connected, sending test message");
+			a_Link.Send("test message");
+			LOGD("Message queued.");
+		}
+
+		virtual void OnError(int a_ErrorCode) override
+		{
+			LOGD("Error while connecting: %d", a_ErrorCode);
+			m_Event.Set();
+		}
+
+	public:
+		cConnectCallbacks(cEvent & a_Event):
+			m_Event(a_Event)
+		{
+		}
+	};
+
+
+	/** Connect callbacks that send a HTTP GET request for google.com when connected. */
+	class cHTTPConnectCallbacks:
+		public cNetwork::cConnectCallbacks
+	{
+		cEvent & m_Event;
+		virtual void OnSuccess(cTCPLink & a_Link) override
+		{
+			LOGD("Connected, sending HTTP GET");
+			if (!a_Link.Send("GET / HTTP/1.0\r\nHost:google.com\r\n\r\n"))
+			{
+				LOGWARNING("Sending HTTP GET failed");
+			}
+			LOGD("HTTP GET queued.");
+		}
+
+		virtual void OnError(int a_ErrorCode) override
+		{
+			LOGD("Error while connecting HTTP: %d", a_ErrorCode);
+			m_Event.Set();
+		}
+
+	public:
+		cHTTPConnectCallbacks(cEvent & a_Event):
+			m_Event(a_Event)
+		{
+		}
+	};
+
+
+	/** Listen callbacks that send a simple welcome message to all connecting peers. */
+	class cListenCallbacks:
+		public cNetwork::cListenCallbacks
+	{
+		virtual void OnAccepted(cTCPLink & a_Link) override
+		{
+			// Send some trivial data:
+			a_Link.Send("Welcome to echo server\n");
+		}
+	};
+
+	cNetworkTest(void)
+	{
+		cEvent evtFinish;
+
+		LOGD("Network test: Connecting to google.com:80, reading front page via HTTP.");
+		if (!cNetwork::Connect("google.com", 80, std::make_shared<cHTTPConnectCallbacks>(evtFinish), std::make_shared<cDumpCallbacks>(evtFinish)))
+		{
+			LOGWARNING("Cannot queue connection to google.com");
+			abort();
+		}
+		LOGD("Connect request has been queued.");
+
+		/*
+		LOGD("Creating a server on port 33033");
+		auto Server = cNetwork::Listen(33033, std::make_shared<cListenCallbacks>(), std::make_shared<cEchoCallbacks>());
+		LOGD("Test server created.");
+
+		LOGD("Connecting to test server");
+		cNetwork::Connect("localhost", 33033, std::make_shared<cConnectCallbacks>(), std::make_shared<cDumpCallbacks>());
+
+		LOGD("Waiting for network operations to finish.");
+		evtFinish.Wait();
+
+		LOGD("Terminating test server.");
+		Server->Close();
+		*/
+
+		evtFinish.Wait();
+		LOGD("Network test finished");
+	}
+} g_NetworkTest;
+
+
+
+
+
+////////////////////////////////////////////////////////////////////////////////
+// Class definitions:
+
+/** Implements the cTCPLink details so that it can represent the single connection between two endpoints. */
+class cTCPLinkImpl:
+	public cTCPLink
+{
+	typedef cTCPLink super;
+public:
+	/** Creates a new link to be queued to connect to a specified host:port.
+	Used for outgoing connections created using cNetwork::Connect().
+	Call Connect() first, before using the link. */
+	cTCPLinkImpl(const cCallbacksPtr a_LinkCallbacks);
+
+	/** Creates a new link based on the given socket.
+	Used for connections accepted in a server using cNetwork::Listen(). */
+	cTCPLinkImpl(evutil_socket_t a_Socket, cCallbacksPtr a_LinkCallbacks);
+
+	/** Queues a connection request to the specified host.
+	a_ConnectCallbacks must be valid.
+	The object must have been constructed by the right constructor (without the Socket param). */
+	bool Connect(const AString & a_Host, UInt16 a_Port, cNetwork::cConnectCallbacksPtr a_ConnectCallbacks);
+
+	// cTCPLink overrides:
+	virtual bool Send(const void * a_Data, size_t a_Length) override;
+	virtual AString GetLocalIP(void) const override;
+	virtual UInt16 GetLocalPort(void) const override;
+	virtual AString GetRemoteIP(void) const override;
+	virtual UInt16 GetRemotePort(void) const override;
+	virtual void Close(void) override;
+	virtual void Drop(void) override;
+
+protected:
+
+	/** Callbacks to call when the connection is established.
+	May be NULL if not used. Only used for outgoing connections (cNetwork::Connect()). */
+	cNetwork::cConnectCallbacksPtr m_ConnectCallbacks;
+
+	/** The LibEvent handle representing this connection. */
+	bufferevent * m_BufferEvent;
+
+
+	/** Callback that LibEvent calls when there's data available from the remote peer. */
+	static void ReadCallback(bufferevent * a_BufferEvent, void * a_Self);
+
+	/** Callback that LibEvent calls when there's a non-data-related event on the socket. */
+	static void EventCallback(bufferevent * a_BufferEvent, short a_What, void * a_Self);
+};
+typedef SharedPtr<cTCPLinkImpl> cTCPLinkImplPtr;
+typedef std::vector<cTCPLinkImplPtr> cTCPLinkImplPtrs;
+
+
+
+
+
+/** Implements the cServerHandle details so that it can represent a real server socket, with a list of clients. */
+class cServerHandleImpl:
+	public cServerHandle
+{
+public:
+	/** Creates a new instance with the specified callbacks.
+	Initializes the internals, but doesn't start listening yet. */
+	cServerHandleImpl(
+		cNetwork::cListenCallbacksPtr a_ListenCallbacks,
+		cTCPLink::cCallbacksPtr a_LinkCallbacks
+	);
+
+	/** Starts listening on the specified port.
+	Both IPv4 and IPv6 interfaces are used, if possible. */
+	bool Listen(UInt16 a_Port);
+
+	// cServerHandle overrides:
+	virtual void Close(void) override;
+	virtual bool IsListening(void) const override { return m_IsListening; }
+
+protected:
+	/** The callbacks used to notify about incoming connections. */
+	cNetwork::cListenCallbacksPtr m_ListenCallbacks;
+
+	/** The callbacks used to create new cTCPLink instances for incoming connections. */
+	cTCPLink::cCallbacksPtr m_LinkCallbacks;
+
+	/** Set to true when the server is initialized successfully and is listening for incoming connections. */
+	bool m_IsListening;
+};
+typedef SharedPtr<cServerHandleImpl> cServerHandleImplPtr;
+typedef std::vector<cServerHandleImplPtr> cServerHandleImplPtrs;
+
+
+
+
+
+class cNetworkSingleton
+{
+	friend class cTCPLinkImpl;
+
+public:
+	/** Returns the singleton instance of this class */
+	static cNetworkSingleton & Get(void);
+
+
+	// The following functions are implementations for the cNetwork class
+
+	/** Queues a TCP connection to be made to the specified host.
+	Calls one the connection callbacks (success, error) when the connection is successfully established, or upon failure.
+	The a_LinkCallbacks is passed to the newly created cTCPLink.
+	Returns true if queueing was successful, false on failure to queue.
+	Note that the return value doesn't report the success of the actual connection; the connection is established asynchronously in the background. */
+	bool Connect(
+		const AString & a_Host,
+		const UInt16 a_Port,
+		cNetwork::cConnectCallbacksPtr a_ConnectCallbacks,
+		cTCPLink::cCallbacksPtr a_LinkCallbacks
+	);
+
+
+	/** Opens up the specified port for incoming connections.
+	Calls an OnAccepted callback for each incoming connection.
+	A cTCPLink with the specified link callbacks is created for each connection.
+	Returns a cServerHandle that can be used to query the operation status and close the server. */
+	cServerHandlePtr Listen(
+		const UInt16 a_Port,
+		cNetwork::cListenCallbacksPtr a_ListenCallbacks,
+		cTCPLink::cCallbacksPtr a_LinkCallbacks
+	);
+
+
+	/** Queues a DNS query to resolve the specified hostname to IP address.
+	Calls one of the callbacks when the resolving succeeds, or when it fails.
+	Returns true if queueing was successful, false if not.
+	Note that the return value doesn't report the success of the actual lookup; the lookup happens asynchronously on the background. */
+	bool HostnameToIP(
+		const AString & a_Hostname,
+		cNetwork::cResolveNameCallbacksPtr a_Callbacks
+	);
+
+
+	/** Queues a DNS query to resolve the specified IP address to a hostname.
+	Calls one of the callbacks when the resolving succeeds, or when it fails.
+	Returns true if queueing was successful, false if not.
+	Note that the return value doesn't report the success of the actual lookup; the lookup happens asynchronously on the background. */
+	bool IPToHostName(
+		const AString & a_IP,
+		cNetwork::cResolveNameCallbacksPtr a_Callbacks
+	);
+
+protected:
+
+	/** The main LibEvent container for driving the event loop. */
+	event_base * m_EventBase;
+
+	/** The LibEvent handle for doing DNS lookups. */
+	evdns_base * m_DNSBase;
+
+	/** Container for all client connections, including ones with pending-connect. */
+	cTCPLinkImplPtrs m_Connections;
+
+	/** Container for all servers that are currently active. */
+	cServerHandleImplPtrs m_Servers;
+
+
+	/** Initializes the LibEvent internals. */
+	cNetworkSingleton(void);
+
+	/** Converts LibEvent-generated log events into log messages in MCS log. */
+	static void LogCallback(int a_Severity, const char * a_Msg);
+
+	/** Runs the thread that LibEvent uses to dispatch event. */
+	static void EventLoopThread(cNetworkSingleton * a_Self);
+};
+
+
+
+
+
+////////////////////////////////////////////////////////////////////////////////
+// cTCPLinkImpl:
+
+cTCPLinkImpl::cTCPLinkImpl(cTCPLink::cCallbacksPtr a_LinkCallbacks):
+	super(a_LinkCallbacks),
+	m_BufferEvent(bufferevent_socket_new(cNetworkSingleton::Get().m_EventBase, -1, BEV_OPT_CLOSE_ON_FREE))
+{
+	bufferevent_setcb(m_BufferEvent, ReadCallback, nullptr, EventCallback, this);
+	bufferevent_enable(m_BufferEvent, EV_READ | EV_WRITE);
+}
+
+
+
+
+
+cTCPLinkImpl::cTCPLinkImpl(evutil_socket_t a_Socket, cTCPLink::cCallbacksPtr a_LinkCallbacks):
+	super(a_LinkCallbacks),
+	m_BufferEvent(bufferevent_socket_new(cNetworkSingleton::Get().m_EventBase, a_Socket, BEV_OPT_CLOSE_ON_FREE))
+{
+	bufferevent_setcb(m_BufferEvent, ReadCallback, nullptr, EventCallback, this);
+	bufferevent_enable(m_BufferEvent, EV_READ | EV_WRITE);
+}
+
+
+
+
+
+/** Schedules the actual connection request.
+Returns true on success, false on failure. */
+bool cTCPLinkImpl::Connect(const AString & a_Host, UInt16 a_Port, cNetwork::cConnectCallbacksPtr a_ConnectCallbacks)
+{
+	ASSERT(bufferevent_getfd(m_BufferEvent) == -1);  // Did you create this object using the right constructor (the one without the Socket param)?
+	ASSERT(a_ConnectCallbacks != nullptr);
+
+	m_ConnectCallbacks = a_ConnectCallbacks;
+
+	// If a_Host is an IP address, schedule a connection immediately:
+	sockaddr_storage sa;
+	int salen = static_cast<int>(sizeof(sa));
+	if (evutil_parse_sockaddr_port(a_Host.c_str(), reinterpret_cast<sockaddr *>(&sa), &salen) == 0)
+	{
+		// Insert the correct port:
+		if (sa.ss_family == AF_INET6)
+		{
+			reinterpret_cast<sockaddr_in6 *>(&sa)->sin6_port = htons(a_Port);
+		}
+		else
+		{
+			reinterpret_cast<sockaddr_in *>(&sa)->sin_port = htons(a_Port);
+		}
+
+		if (bufferevent_socket_connect(m_BufferEvent, reinterpret_cast<sockaddr *>(&sa), salen) == 0)
+		{
+			// Success
+			return true;
+		}
+		// Failure
+		return false;
+	}
+
+	// a_Host is a hostname, connect after a lookup:
+	if (bufferevent_socket_connect_hostname(m_BufferEvent, cNetworkSingleton::Get().m_DNSBase, AF_UNSPEC, a_Host.c_str(), a_Port) == 0)
+	{
+		// Success
+		return true;
+	}
+	// Failure
+	return false;
+}
+
+
+
+
+
+bool cTCPLinkImpl::Send(const void * a_Data, size_t a_Length)
+{
+	return (bufferevent_write(m_BufferEvent, a_Data, a_Length) == 0);
+}
+
+
+
+
+
+AString cTCPLinkImpl::GetLocalIP(void) const
+{
+	// TODO
+	ASSERT(!"cTCPLinkImpl::GetLocalIP: Not implemented yet");
+	return "";
+}
+
+
+
+
+
+UInt16 cTCPLinkImpl::GetLocalPort(void) const
+{
+	// TODO
+	ASSERT(!"cTCPLinkImpl::GetLocalPort(): Not implemented yet");
+	return 0;
+}
+
+
+
+
+
+AString cTCPLinkImpl::GetRemoteIP(void) const
+{
+	// TODO
+	ASSERT(!"cTCPLinkImpl::GetRemoteIP(): Not implemented yet");
+	return "";
+}
+
+
+
+
+
+UInt16 cTCPLinkImpl::GetRemotePort(void) const
+{
+	// TODO
+	ASSERT(!"cTCPLinkImpl::GetRemotePort(): Not implemented yet");
+	return 0;
+}
+
+
+
+
+
+void cTCPLinkImpl::Close(void)
+{
+	// TODO
+	ASSERT(!"cTCPLinkImpl::Close(): Not implemented yet");
+}
+
+
+
+
+
+void cTCPLinkImpl::Drop(void)
+{
+	// TODO
+	ASSERT(!"cTCPLinkImpl::Drop(): Not implemented yet");
+}
+
+
+
+
+
+
+void cTCPLinkImpl::ReadCallback(bufferevent * a_BufferEvent, void * a_Self)
+{
+	ASSERT(a_Self != nullptr);
+	cTCPLinkImpl * Self = static_cast<cTCPLinkImpl *>(a_Self);
+	ASSERT(Self->m_Callbacks != nullptr);
+
+	// Read all the incoming data, in 1024-byte chunks:
+	char data[1024];
+	size_t length;
+	while ((length = bufferevent_read(a_BufferEvent, data, sizeof(data))) > 0)
+	{
+		Self->m_Callbacks->OnReceivedData(*Self, data, length);
+	}
+}
+
+
+
+
+
+void cTCPLinkImpl::EventCallback(bufferevent * a_BufferEvent, short a_What, void * a_Self)
+{
+	ASSERT(a_Self != nullptr);
+	cTCPLinkImpl * Self = static_cast<cTCPLinkImpl *>(a_Self);
+
+	// If an error is reported, call the error callback:
+	if (a_What & BEV_EVENT_ERROR)
+	{
+		// Choose the proper callback to call based on whether we were waiting for connection or not:
+		if (Self->m_ConnectCallbacks != nullptr)
+		{
+			Self->m_ConnectCallbacks->OnError(EVUTIL_SOCKET_ERROR());
+		}
+		else
+		{
+			Self->m_Callbacks->OnError(*Self, EVUTIL_SOCKET_ERROR());
+		}
+		return;
+	}
+
+	// Pending connection succeeded, call the connection callback:
+	if (a_What & BEV_EVENT_CONNECTED)
+	{
+		if (Self->m_ConnectCallbacks != nullptr)
+		{
+			Self->m_ConnectCallbacks->OnSuccess(*Self);
+			// Reset the connect callbacks so that later errors get reported through the link callbacks:
+			Self->m_ConnectCallbacks.reset();
+			return;
+		}
+	}
+
+	// If the connectino has been closed, call the link callback:
+	if (a_What & BEV_EVENT_EOF)
+	{
+		Self->m_Callbacks->OnRemoteClosed(*Self);
+		return;
+	}
+	
+	// Unknown event, report it:
+	LOGWARNING("cTCPLinkImpl: Unhandled LibEvent event %d (0x%x)", a_What, a_What);
+	ASSERT(!"cTCPLinkImpl: Unhandled LibEvent event");
+}
+
+
+
+
+
+////////////////////////////////////////////////////////////////////////////////
+// cServerHandleImpl:
+
+cServerHandleImpl::cServerHandleImpl(cNetwork::cListenCallbacksPtr a_ListenCallbacks, cTCPLink::cCallbacksPtr a_LinkCallbacks):
+	m_ListenCallbacks(a_ListenCallbacks),
+	m_LinkCallbacks(a_LinkCallbacks)
+{
+	// TODO
+	ASSERT(!"Not implemented yet!");
+}
+
+
+
+
+
+void cServerHandleImpl::Close(void)
+{
+	// TODO
+	ASSERT(!"Not implemented yet!");
+}
+
+
+
+
+
+bool cServerHandleImpl::Listen(UInt16 a_Port)
+{
+	// TODO
+	ASSERT(!"Not implemented yet!");
+	return false;
+}
+
+
+
+
+
+////////////////////////////////////////////////////////////////////////////////
+// cNetwork:
+
+bool cNetwork::Connect(
+	const AString & a_Host,
+	const UInt16 a_Port,
+	cNetwork::cConnectCallbacksPtr a_ConnectCallbacks,
+	cTCPLink::cCallbacksPtr a_LinkCallbacks
+)
+{
+	return cNetworkSingleton::Get().Connect(a_Host, a_Port, a_ConnectCallbacks, a_LinkCallbacks);
+}
+
+
+
+
+
+cServerHandlePtr cNetwork::Listen(
+	const UInt16 a_Port,
+	cNetwork::cListenCallbacksPtr a_ListenCallbacks,
+	cTCPLink::cCallbacksPtr a_LinkCallbacks
+)
+{
+	return cNetworkSingleton::Get().Listen(a_Port, a_ListenCallbacks, a_LinkCallbacks);
+}
+
+
+
+
+
+bool cNetwork::HostnameToIP(
+	const AString & a_Hostname,
+	cNetwork::cResolveNameCallbacksPtr a_Callbacks
+)
+{
+	return cNetworkSingleton::Get().HostnameToIP(a_Hostname, a_Callbacks);
+}
+
+
+
+
+
+bool cNetwork::IPToHostName(
+	const AString & a_IP,
+	cNetwork::cResolveNameCallbacksPtr a_Callbacks
+)
+{
+	return cNetworkSingleton::Get().IPToHostName(a_IP, a_Callbacks);
+}
+
+
+
+
+////////////////////////////////////////////////////////////////////////////////
+// cTCPLink:
+
+cTCPLink::cTCPLink(cCallbacksPtr a_Callbacks):
+	m_Callbacks(a_Callbacks)
+{
+}
+
+
+
+
+////////////////////////////////////////////////////////////////////////////////
+// cNetworkSingleton:
+
+cNetworkSingleton::cNetworkSingleton(void)
+{
+	// Windows: initialize networking:
+	#ifdef _WIN32
+		WSADATA wsaData;
+		memset(&wsaData, 0, sizeof(wsaData));
+		WSAStartup (MAKEWORD(2, 2), &wsaData);
+	#endif  // _WIN32
+
+	// Initialize LibEvent logging:
+	event_set_log_callback(LogCallback);
+
+	// Initialize threading:
+	#if defined(EVTHREAD_USE_WINDOWS_THREADS_IMPLEMENTED)
+		evthread_use_windows_threads();
+	#elif defined(EVTHREAD_USE_PTHREADS_IMPLEMENTED)
+		evthread_use_pthreads();
+	#else
+		#error No threading implemented for EVTHREAD
+	#endif
+
+	// Create the main event_base:
+	m_EventBase = event_base_new();
+	if (m_EventBase == nullptr)
+	{
+		LOGERROR("Failed to initialize LibEvent. The server will now terminate.");
+		abort();
+	}
+
+	// Create the DNS lookup helper:
+	m_DNSBase = evdns_base_new(m_EventBase, 1);
+	if (m_DNSBase == nullptr)
+	{
+		LOGERROR("Failed to initialize LibEvent's DNS subsystem. The server will now terminate.");
+		abort();
+	}
+
+	// Create the event loop thread:
+	std::thread::thread(EventLoopThread, this).detach();
+}
+
+
+
+
+
+cNetworkSingleton & cNetworkSingleton::Get(void)
+{
+	static cNetworkSingleton Instance;
+	return Instance;
+}
+
+
+bool cNetworkSingleton::Connect(
+	const AString & a_Host,
+	const UInt16 a_Port,
+	cNetwork::cConnectCallbacksPtr a_ConnectCallbacks,
+	cTCPLink::cCallbacksPtr a_LinkCallbacks
+)
+{
+	// Add a connection request to the queue:
+	cTCPLinkImplPtr ConnRequest = std::make_shared<cTCPLinkImpl>(a_LinkCallbacks);
+	m_Connections.push_back(ConnRequest);
+
+	// Queue the connection:
+	if (!ConnRequest->Connect(a_Host, a_Port, a_ConnectCallbacks))
+	{
+		// TODO: m_Connections.remove(ConnRequest);
+		return false;
+	}
+
+	// Everything successful, return success:
+	return true;
+}
+
+
+
+
+
+cServerHandlePtr cNetworkSingleton::Listen(
+	const UInt16 a_Port,
+	cNetwork::cListenCallbacksPtr a_ListenCallbacks,
+	cTCPLink::cCallbacksPtr a_LinkCallbacks
+)
+{
+	cServerHandleImplPtr res = std::make_shared<cServerHandleImpl>(a_ListenCallbacks, a_LinkCallbacks);
+	if (!res->Listen(a_Port))
+	{
+		return res;
+	}
+	m_Servers.push_back(res);
+	return res;
+}
+
+
+
+
+
+bool cNetworkSingleton::HostnameToIP(
+	const AString & a_Hostname,
+	cNetwork::cResolveNameCallbacksPtr a_Callbacks
+)
+{
+	// TODO
+	ASSERT(!"Not implemented yet!");
+	return false;
+}
+
+
+
+
+bool cNetworkSingleton::IPToHostName(
+	const AString & a_IP,
+	cNetwork::cResolveNameCallbacksPtr a_Callbacks
+)
+{
+	// TODO
+	ASSERT(!"Not implemented yet!");
+	return false;
+}
+
+
+
+
+void cNetworkSingleton::LogCallback(int a_Severity, const char * a_Msg)
+{
+	switch (a_Severity)
+	{
+		case _EVENT_LOG_DEBUG: LOGD      ("LibEvent: %s", a_Msg); break;
+		case _EVENT_LOG_MSG:   LOG       ("LibEvent: %s", a_Msg); break;
+		case _EVENT_LOG_WARN:  LOGWARNING("LibEvent: %s", a_Msg); break;
+		case _EVENT_LOG_ERR:   LOGERROR  ("LibEvent: %s", a_Msg); break;
+		default:
+		{
+			printf("LibEvent: %s", a_Msg);
+			break;
+		}
+	}
+}
+
+
+
+
+
+void cNetworkSingleton::EventLoopThread(cNetworkSingleton * a_Self)
+{
+	event_base_loop(a_Self->m_EventBase, EVLOOP_NO_EXIT_ON_EMPTY);
+}
+
+
+
+
diff --git a/src/OSSupport/Network.h b/src/OSSupport/Network.h
new file mode 100644
index 000000000..447cd457b
--- /dev/null
+++ b/src/OSSupport/Network.h
@@ -0,0 +1,188 @@
+
+// Network.h
+
+// Declares the classes used for the Network API
+
+
+
+
+
+#pragma once
+
+
+
+
+
+/** Interface that provides the methods available on a single TCP connection. */
+class cTCPLink
+{
+	friend class cNetwork;
+
+public:
+	class cCallbacks
+	{
+	public:
+		/** Called when there's data incoming from the remote peer. */
+		virtual void OnReceivedData(cTCPLink & a_Link, const char * a_Data, size_t a_Length) = 0;
+
+		/** Called when the remote end closes the connection.
+		The link is still available for connection information query (IP / port).
+		Sending data on the link is not an error, but the data won't be delivered. */
+		virtual void OnRemoteClosed(cTCPLink & a_Link) = 0;
+
+		/** Called when an error is detected on the connection. */
+		virtual void OnError(cTCPLink & a_Link, int a_ErrorCode) = 0;
+	};
+	typedef SharedPtr<cCallbacks> cCallbacksPtr;
+
+
+	/** Queues the specified data for sending to the remote peer.
+	Returns true on success, false on failure. Note that this success or failure only reports the queue status, not the actual data delivery. */
+	virtual bool Send(const void * a_Data, size_t a_Length) = 0;
+
+	/** Queues the specified data for sending to the remote peer.
+	Returns true on success, false on failure. Note that this success or failure only reports the queue status, not the actual data delivery. */
+	bool Send(const AString & a_Data)
+	{
+		return Send(a_Data.data(), a_Data.size());
+	}
+
+	/** Returns the IP address of the local endpoint of the connection. */
+	virtual AString GetLocalIP(void) const = 0;
+
+	/** Returns the port used by the local endpoint of the connection. */
+	virtual UInt16 GetLocalPort(void) const = 0;
+
+	/** Returns the IP address of the remote endpoint of the connection. */
+	virtual AString GetRemoteIP(void) const = 0;
+
+	/** Returns the port used by the remote endpoint of the connection. */
+	virtual UInt16 GetRemotePort(void) const = 0;
+
+	/** Closes the link gracefully.
+	The link will keep trying to send the queued data, then it will send the FIN packet. */
+	virtual void Close(void) = 0;
+
+	/** Drops the connection without any more processing.
+	Sends the RST packet, queued outgoing and incoming data is lost. */
+	virtual void Drop(void) = 0;
+
+protected:
+	/** Callbacks to be used for the various situations. */
+	cCallbacksPtr m_Callbacks;
+
+
+	/** Creates a new link, with the specified callbacks. */
+	cTCPLink(cCallbacksPtr a_Callbacks);
+};
+
+
+
+
+
+/** Interface that provides the methods available on a listening server socket. */
+class cServerHandle
+{
+	friend class cNetwork;
+public:
+
+	/** Stops the server, no more incoming connections will be accepted. */
+	virtual void Close(void) = 0;
+
+	/** Returns true if the server has been started correctly and is currently listening for incoming connections. */
+	virtual bool IsListening(void) const = 0;
+};
+typedef SharedPtr<cServerHandle> cServerHandlePtr;
+
+
+
+
+
+class cNetwork
+{
+public:
+	/** Callbacks used for connecting to other servers as a client. */
+	class cConnectCallbacks
+	{
+	public:
+		/** Called when the Connect call succeeds.
+		Provides the newly created link that can be used for communication. */
+		virtual void OnSuccess(cTCPLink & a_Link) = 0;
+
+		/** Called when the Connect call fails. */
+		virtual void OnError(int a_ErrorCode) = 0;
+	};
+	typedef SharedPtr<cConnectCallbacks> cConnectCallbacksPtr;
+
+
+	/** Callbacks used when listening for incoming connections as a server. */
+	class cListenCallbacks
+	{
+	public:
+		/** Called when the TCP server created with Listen() accepts an incoming connection.
+		Provides the newly created Link that can be used for communication. */
+		virtual void OnAccepted(cTCPLink & a_Link) = 0;
+	};
+	typedef SharedPtr<cListenCallbacks> cListenCallbacksPtr;
+
+
+	/** Callbacks used when resolving names to IPs. */
+	class cResolveNameCallbacks
+	{
+	public:
+		/** Called when the hostname is successfully resolved into an IP address. */
+		virtual void OnNameResolved(const AString & a_Name, const AString & a_IP) = 0;
+
+		/** Called when an error is encountered while resolving. */
+		virtual void OnError(int a_ErrorCode) = 0;
+	};
+	typedef SharedPtr<cResolveNameCallbacks> cResolveNameCallbacksPtr;
+
+
+	/** Queues a TCP connection to be made to the specified host.
+	Calls one the connection callbacks (success, error) when the connection is successfully established, or upon failure.
+	The a_LinkCallbacks is passed to the newly created cTCPLink.
+	Returns true if queueing was successful, false on failure to queue.
+	Note that the return value doesn't report the success of the actual connection; the connection is established asynchronously in the background. */
+	static bool Connect(
+		const AString & a_Host,
+		const UInt16 a_Port,
+		cConnectCallbacksPtr a_ConnectCallbacks,
+		cTCPLink::cCallbacksPtr a_LinkCallbacks
+	);
+
+
+	/** Opens up the specified port for incoming connections.
+	Calls an OnAccepted callback for each incoming connection.
+	A cTCPLink with the specified link callbacks is created for each connection.
+	Returns a cServerHandle that can be used to query the operation status and close the server. */
+	static cServerHandlePtr Listen(
+		const UInt16 a_Port,
+		cListenCallbacksPtr a_ListenCallbacks,
+		cTCPLink::cCallbacksPtr a_LinkCallbacks
+	);
+
+
+	/** Queues a DNS query to resolve the specified hostname to IP address.
+	Calls one of the callbacks when the resolving succeeds, or when it fails.
+	Returns true if queueing was successful, false if not.
+	Note that the return value doesn't report the success of the actual lookup; the lookup happens asynchronously on the background. */
+	static bool HostnameToIP(
+		const AString & a_Hostname,
+		cResolveNameCallbacksPtr a_Callbacks
+	);
+
+
+	/** Queues a DNS query to resolve the specified IP address to a hostname.
+	Calls one of the callbacks when the resolving succeeds, or when it fails.
+	Returns true if queueing was successful, false if not.
+	Note that the return value doesn't report the success of the actual lookup; the lookup happens asynchronously on the background. */
+	static bool IPToHostName(
+		const AString & a_IP,
+		cResolveNameCallbacksPtr a_Callbacks
+	);
+};
+
+
+
+