qftp2.cpp

See Appendix B for a description of the programs included on this companion disk. RESOURCE.WRI iden

		sockAddr.sin_addr = *((LPIN_ADDR)*lpHostEnt->h_addr_list);
						
		// Connect the socket
		if( nConnect = connect(hControlSocket, (LPSOCKADDR)&sockAddr, 
					sizeof(sockAddr)))
			{
				int iWinsockErr = WSAGetLastError();
				wsprintf(gszCommandBuffer,
							"Error #%d occurred while connecting socket!!", 
							iWinsockErr);
				MessageBeep(MB_ICONSTOP);
				MessageBox(NULL, gszCommandBuffer, lpszFunctionName, 
							MB_OK|MB_ICONSTOP);
				return(INVALID_SOCKET);
			}
			
		if (ReadFTPServerReply(hControlSocket) >= 400)
			return(INVALID_SOCKET);
		else
			return(hControlSocket);
	}	

SOCKET RequestDataConnection(SOCKET hControlSocket, SOCKET hListenSocket)
	{
		SOCKADDR_IN sockAddr;					// Socket address structure
    int iLength;									// Length of the address structure
    UINT nLocalPort;							// Local port for listening
		UINT nReplyCode;							// FTP server reply code

		lpszFunctionName = "RequestDataConnection";

    // Get the address for the hListenSocket
		iLength = sizeof(sockAddr);
		if (getsockname(hListenSocket, (LPSOCKADDR)&sockAddr, 
					&iLength) == SOCKET_ERROR)
			{
				int iWinsockErr = WSAGetLastError();
				wsprintf(gszCommandBuffer,
							"Error #%d occurred while getting listen socket name!!", 
							iWinsockErr);
				MessageBeep(MB_ICONSTOP);
				MessageBox(NULL, gszCommandBuffer, lpszFunctionName, 
							MB_OK|MB_ICONSTOP);
				return(INVALID_SOCKET);
			}

		// Extract the local port from the hListenSocket
		nLocalPort = sockAddr.sin_port;
								
		// Now, reuse the socket address structure to 
		// get the IP address from the control socket.
		if (getsockname(hControlSocket, (LPSOCKADDR)&sockAddr, 
					&iLength) == SOCKET_ERROR)
			{
				int iWinsockErr = WSAGetLastError();
				wsprintf(gszCommandBuffer,
							"Error #%d occurred while getting control socket name!!", 
							iWinsockErr);
				MessageBeep(MB_ICONSTOP);
				MessageBox(NULL, gszCommandBuffer, lpszFunctionName, 
							MB_OK|MB_ICONSTOP);
				return(INVALID_SOCKET);
			}
					
		// Format the PORT command with the correct numbers.
		wsprintf(gszCommandBuffer, "PORT %d,%d,%d,%d,%d,%d\r\n", 
					sockAddr.sin_addr.S_un.S_un_b.s_b1, 
					sockAddr.sin_addr.S_un.S_un_b.s_b2,
					sockAddr.sin_addr.S_un.S_un_b.s_b3,
					sockAddr.sin_addr.S_un.S_un_b.s_b4,
					// Remember, the port is in network byte order. The FTP server
					// expects to see the high-order byte from the port (in terms of 
					// the network byte order) first. As such, from a PC, (which uses
					// little endian byte order) the program must transmit the low-order 
					// byte first and then the high-order. (If this is confusing, see the
					// "Internet Programming" chapter entitled "Time and the Network
					// Byte Order".
					nLocalPort & 0xFF,	
					nLocalPort >> 8);
																
		// Tell the server which port to use for data.
		if (nReplyCode = SendFTPCommand(hControlSocket, gszCommandBuffer)
					!= 200)
			{
				wsprintf(gszCommandBuffer, 
							"Error %d from PORT command to server!", 
							nReplyCode);
				MessageBeep(MB_ICONSTOP);
				MessageBox(NULL, gszCommandBuffer, lpszFunctionName, 
							MB_OK|MB_ICONSTOP);
				return(INVALID_SOCKET);
			}
		else
			return(hListenSocket);
	}	
	
SOCKET CreateListenSocket(SOCKET hControlSocket)
	{
		SOCKADDR_IN sockAddr;					// Socket address structure
		SOCKET hListenSocket;					// Handle for the listener socket
		
		lpszFunctionName = "CreateListenSocket";

		if ((hListenSocket = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP)) 
					== INVALID_SOCKET)
			{
				int iWinsockErr = WSAGetLastError();
				wsprintf(gszCommandBuffer,
							"Error #%d occurred while creating socket!!", 
							iWinsockErr);
				MessageBeep(MB_ICONSTOP);
				MessageBox(NULL, gszCommandBuffer, lpszFunctionName, 
							MB_OK|MB_ICONSTOP);
				return(INVALID_SOCKET);
			}
		// Let the system assign a socket address	
		sockAddr.sin_family = AF_INET;		
		sockAddr.sin_port = htons(0);		// htons() is just a reminder.
		sockAddr.sin_addr.s_addr = INADDR_ANY;
						
		// Bind the socket
		if (bind(hListenSocket, (LPSOCKADDR)&sockAddr, sizeof(sockAddr)))
			{
				int iWinsockErr = WSAGetLastError();
				wsprintf(gszCommandBuffer,
							"Error #%d occurred while binding socket!!", 
							iWinsockErr);
				MessageBeep(MB_ICONSTOP);
				MessageBox(NULL, gszCommandBuffer, lpszFunctionName, 
							MB_OK|MB_ICONSTOP);
				return(INVALID_SOCKET);
			}

		// Listen for the FTP server connection
		if (listen(hListenSocket, QUEUE_SIZE))	
			{
				int iWinsockErr = WSAGetLastError();
				wsprintf(gszCommandBuffer, 
							"Error %d on listen socket!!", 
							iWinsockErr);   
				MessageBeep(MB_ICONSTOP);
				MessageBox(NULL, gszCommandBuffer, lpszFunctionName, 
							MB_OK|MB_ICONSTOP);
				return(INVALID_SOCKET);
			}
		
		// Ask the server to connect to the port monitored by the listener socket
		return(RequestDataConnection(hControlSocket, hListenSocket));
	}	
		
SOCKET AcceptDataConnection(SOCKET hListenSocket)
	{
		SOCKET hDataSocket;				// Handle for socket that receives data
		SOCKADDR_IN sockAddr;			// Socket address structure
		int iAddrLength;					// The length of the socket address
	
		lpszFunctionName = "AcceptDataConnection";

		hDataSocket = accept(hListenSocket, (LPSOCKADDR)&sockAddr, 
				&iAddrLength); 
				
		// Close the listener socket since it is no longer needed
		closesocket(hListenSocket);
		
		if (hDataSocket == INVALID_SOCKET)
			{
				int iWinsockErr = WSAGetLastError();
				wsprintf(gszCommandBuffer, 
							"Error %d while accepting a data socket connection!!", 
							iWinsockErr);   
				MessageBeep(MB_ICONSTOP);
				MessageBox(NULL, gszCommandBuffer, lpszFunctionName, 
							MB_OK|MB_ICONSTOP);
				return(INVALID_SOCKET);
			}
		else
			return(hDataSocket);
	}	

VOID DemonstrateCommand(SOCKET hControlChannel)
	{
		SOCKET hDataChannel;		// Handle for socket to receive server data
		SOCKET hListenSocket;		// Handle for the listener socket
		UINT nReplyCode;				// FTP server reply code

		lpszFunctionName = "DemonstrateCommand";
			  
		if ((hListenSocket = CreateListenSocket(hControlChannel))
			 	== INVALID_SOCKET)
			return;
					
		// Hard code the NLST command for testing.
		if (nReplyCode = SendFTPCommand(hControlChannel, 
					"NLST\r\n") >= 400)
			return;
			
		// Accept the data connection from the server. Note that
		// AcceptDataConnection() closes the hListenSocket.
		if ((hDataChannel = AcceptDataConnection(hListenSocket))
					== INVALID_SOCKET)
			return;
			
		ReadDataChannel(hDataChannel, "NLST.TXT");
		closesocket(hDataChannel);
		return;
	} 

int PASCAL WinMain(HANDLE hInstance, HANDLE hPrevInstance, 
			LPSTR lpszCmdParam, int nCmdShow)
	{
		WSADATA wsaData;							// Winsock implementation details
		SOCKET hControlChannel;				// Socket handle for the control channel
		UINT nReplyCode;							// FTP server reply code

		lpszFunctionName = "WinMain";
		
		if (WSAStartup(WINSOCK_VERSION, &wsaData))
			{
				MessageBeep(MB_ICONSTOP);
				MessageBox(NULL, "Could not load Windows Sockets DLL.", 
							lpszFunctionName, MB_OK|MB_ICONSTOP);
				return(NULL);
			}
						
		hControlChannel = ConnectFTPControlSocket((LPSTR)HOST_NAME);

		if (hControlChannel != INVALID_SOCKET)
			{
				// If the control socket is valid, perform an anonymous FTP login.
				nReplyCode = AnonymousFTPLogIn(hControlChannel);
				             
				if (nReplyCode == 230)	// User logged in; okay to proceed.
					{
						DemonstrateCommand(hControlChannel);
						SendFTPCommand(hControlChannel, "QUIT\r\n");
						closesocket(hControlChannel);
					}
			}
		
		WSACleanup();
		MessageBeep(MB_ICONEXCLAMATION);
		MessageBox(NULL, "THE END!!", PROG_NAME, MB_OK|MB_ICONEXCLAMATION);
		return(NULL); 
	}