www.pudn.com > DataGram.zip > dclient.cpp

// 
// DClient.cpp 
// 
// Extremely simple, totally useless datagram client example. 
// Works in conjunction with DServer.cpp. 
// 
// The program attempts to connect to the server and port 
// specified on the command line. The DServer program prints 
// the needed information when it is started. Once connected, 
// the program sends data to the server, waits for a response 
// and then exits. 
// 
// Compile and link with wsock32.lib 
// 
// Pass the server name and port number on the command line.  
// 
// Example: DClient MyMachineName 2000 
// 
 
#include  
#include  
#include  
 
// Function prototype 
void DatagramClient(char *szServer, short nPort); 
 
// Helper macro for displaying errors 
#define PRINTERROR(s)	\ 
		fprintf(stderr,"\n%: %d\n", s, WSAGetLastError()) 
 
//////////////////////////////////////////////////////////// 
 
void main(int argc, char **argv) 
{ 
	WORD wVersionRequested = MAKEWORD(1,1); 
	WSADATA wsaData; 
	int nRet; 
	short nPort; 
 
	// 
	// Check for the host and port arguments 
	// 
	if (argc != 3) 
	{ 
		fprintf(stderr,"\nSyntax: dclient ServerName PortNumber\n"); 
		return; 
	} 
 
	nPort = atoi(argv[2]); 
 
	// 
	// Initialize WinSock and check the version 
	// 
	nRet = WSAStartup(wVersionRequested, &wsaData); 
	if (wsaData.wVersion != wVersionRequested) 
	{	 
		fprintf(stderr,"\n Wrong version\n"); 
		return; 
	} 
 
	// 
	// Go do all the stuff a datagram client does 
	// 
	DatagramClient(argv[1], nPort); 
	 
	// 
	// Release WinSock 
	// 
	WSACleanup(); 
} 
 
//////////////////////////////////////////////////////////// 
 
void DatagramClient(char *szServer, short nPort) 
{ 
 
	printf("\nDatagram Client sending to server: %s on port: %d", 
				szServer, nPort); 
 
	// 
	// Find the server 
	// 
    LPHOSTENT lpHostEntry; 
 
	lpHostEntry = gethostbyname(szServer); 
    if (lpHostEntry == NULL) 
    { 
        PRINTERROR("gethostbyname()"); 
        return; 
    } 
 
 
	// 
	// Create a UDP/IP datagram socket 
	// 
	SOCKET	theSocket; 
 
	theSocket = socket(AF_INET,			// Address family 
					   SOCK_DGRAM,		// Socket type 
					   IPPROTO_UDP);	// Protocol 
	if (theSocket == INVALID_SOCKET) 
	{ 
		PRINTERROR("socket()"); 
		return; 
	} 
 
	// 
	// Fill in the address structure for the server 
	// 
	SOCKADDR_IN saServer; 
 
	saServer.sin_family = AF_INET; 
	saServer.sin_addr = *((LPIN_ADDR)*lpHostEntry->h_addr_list); 
										// ^ Server's address 
	saServer.sin_port = htons(nPort);	// Port number from command line 
 
	// 
	// Send data to the server 
	// 
	char szBuf[256]; 
	int nRet; 
 
	strcpy(szBuf, "From the Client"); 
	nRet = sendto(theSocket,				// Socket 
				  szBuf,					// Data buffer 
				  strlen(szBuf),			// Length of data 
				  0,						// Flags 
				  (LPSOCKADDR)&saServer,	// Server address 
				  sizeof(struct sockaddr)); // Length of address 
	if (nRet == SOCKET_ERROR) 
	{ 
		PRINTERROR("sendto()"); 
		closesocket(theSocket); 
		return; 
	} 
 
	// 
	// Wait for the reply 
	// 
	memset(szBuf, 0, sizeof(szBuf)); 
	int nFromLen; 
 
	nFromLen = sizeof(struct sockaddr); 
	recvfrom(theSocket,						// Socket 
			 szBuf,							// Receive buffer 
			 sizeof(szBuf),					// Length of receive buffer 
			 0,								// Flags 
			 (LPSOCKADDR)&saServer,			// Buffer to receive sender's address 
			 &nFromLen);					// Length of address buffer 
	if (nRet == SOCKET_ERROR) 
	{ 
		PRINTERROR("recvfrom()"); 
		closesocket(theSocket); 
		return; 
	} 
 
	// 
	// Display the data that was received 
	// 
	printf("\nData received: %s", szBuf); 
 
	closesocket(theSocket); 
	return; 
}