/***************************************************************************
 *   Copyright (C) 2005 by halit                                           *
 *   halit@localhost                                                       *
 *                                                                         *
 ***************************************************************************/

#include <stdio.h>      /* for printf() and fprintf() 		     	*/
#include <sys/socket.h> /* for socket(), connect(), send() and recv()	*/ 
#include <arpa/inet.h>  /* for sockaddr_in and inet_addr()		*/
#include <stdlib.h>     /* for atoi()                         		*/
#include <string.h>     /* for memset()                  		*/
#include <unistd.h>     /* for close()                   		*/

/* Maximum outstanding conn. requests */
#define MAXPENDING 5
#define RCVBUFSIZE 32

void DieWithError(char *errorMessage); /* error handling func. 			*/
void HandleTCPClient(int clntSocket);  /* for TCP client handling function 	*/

int main(int argc, char *argv[])
{
	int servSock, clntSock;
	struct sockaddr_in echoServAddr;
	struct sockaddr_in echoClntAddr; 
	unsigned short echoServPort;
	unsigned int clntLen;   /* Length of client address data structure */

	echoServPort = 7; /* well-known port for echo service */
	
	/* Create socket for incoming connections */
	if((servSock = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP)) < 0)
		DieWithError( "socket() failed\n" );
	
	/* Construct Local address structure */
	memset(&echoServAddr, 0, sizeof(echoServAddr));
	echoServAddr.sin_family = AF_INET;
	echoServAddr.sin_addr.s_addr = htonl(INADDR_ANY);
	echoServAddr.sin_port = htons(echoServPort);

	/* Bind to the local address */
	if(bind(servSock, (struct sockaddr *) &echoServAddr, sizeof(echoServAddr)) < 0)
		DieWithError( "bind() failed\n" );
	
	/* Mark the socket so it will listen for incoming connections */
	if(listen(servSock, MAXPENDING) < 0)
		DieWithError( "listen() failed\n" );
	for(;;)
	{
		printf("listening\n");
		/* Wait for a client to connect */
		if((clntSock = accept(servSock, NULL, NULL) < 0))
			DieWithError( "bind() failed\n" );
	
		/* clntSock is connected to a client */
		printf( "Handling client %s\n", inet_ntoa(echoClntAddr.sin_addr));
	
		HandleTCPClient(clntSock); 
	}
	/* NOT REACHED */
}

void DieWithError(char *errorMessage)	
{
	printf(errorMessage);
	exit(0);
}

void HandleTCPClient(int clntSocket)	
{
	char echoBuffer[RCVBUFSIZE];
	int recvMsgSize;

	/* Receive message from client */
	if((recvMsgSize=recv(clntSocket, echoBuffer, RCVBUFSIZE, 0)) < 0) 
		DieWithError("recv() failed\n");
		
	/* Send received string and receive again until the end of transmission */
	while(recvMsgSize > 0)   /* zero indicates end of transmission */  
	{
		/* Echo message back to client */
		if((send(clntSocket, echoBuffer, recvMsgSize, 0)) != recvMsgSize)
			DieWithError("send() failed\n");
		
		/* Receive message from client */
		if((recvMsgSize=recv(clntSocket, echoBuffer, RCVBUFSIZE, 0)) < 0) 
			DieWithError("recv() failed\n");
	}	
	close(clntSocket);
}

/***************************************************************************
 *   Copyright (C) 2005 by halit                                           *
 *   halit@localhost                                                       *
 *                                                                         *
 ***************************************************************************/

#include <stdio.h>      /* for printf()                    */
#include <sys/socket.h> /* for socket(), connect(), send() and recv() */ 
#include <arpa/inet.h>  /* for sockaddr_in and inet_addr() */
#include <stdlib.h>     /* for atoi()                      */
#include <string.h>     /* for memset()                    */
#include <unistd.h>     /* for close()                     */

/* Size of receive buffer */
#define RCVBUFSIZE 32

void DieWithError(char *errorMessage); /* error handling function */

int main(int argc, char *argv[])
{
	int sock;
	struct sockaddr_in echoServAddr;
	unsigned short echoServPort;
	char *servIP;
	char *echoString;
	char echoBuffer[RCVBUFSIZE];
	unsigned int echoStringLen;
	int bytesRcvd, totalBytesRcvd;

	if (argc != 3)
	{
		printf( "Usage: %s <Server IP> <Echo Word> \n" , argv[0]);
		exit(1);
	}
	servIP = argv[1];
	echoString = argv[2];
	echoServPort = 7;   /* well-known port for echo service */
	
	/* Create a reliable, stream socket using TCP */
	if((sock = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP)) < 0)
		DieWithError( "socket() failed\n" );
  
	/* Construct the server address structure */
	memset(&echoServAddr, 0, sizeof(echoServAddr));
	echoServAddr.sin_family = AF_INET;
	echoServAddr.sin_addr.s_addr = inet_addr(servIP);
	echoServAddr.sin_port = htons(echoServPort);
	
	/* Establish a connection to the echo cerver */
	if(connect(sock, (struct sockaddr *) &echoServAddr, sizeof(echoServAddr)) < 0)
		DieWithError( "socket() failed\n" );
	
	echoStringLen = strlen(echoString); /*Determine the input length */
	
	/* Send the string to the server */
	if((send(sock, echoString, echoStringLen, 0)) != echoStringLen)
		DieWithError( "send() failed\n" );
	
	/* receive the same string back from the server */
	if((bytesRcvd = recv(sock, echoBuffer, RCVBUFSIZE - 1, 0)) <= 0)
		DieWithError( "socket() failed\n" );
	
	printf(echoBuffer); 
	
	printf( "\n" );
	close(sock);
	exit(0);
}

void DieWithError(char *errorMessage)
{
	printf(errorMessage);
	exit(0);
}