udpecho2.c

Error Exit Code for Linux operating system. This code is efficient and modified by a team from a re

/* UDPecho.c - main, UDPecho */

#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>

#include <errno.h>
extern int	errno;

/* 8-Jan-08: to measure time */
#include <time.h>
#include <sys/time.h>

int	UDPecho(const char *host, const char *service);
int	errexit(const char *format, ...);
int	connectUDP(const char *host, const char *service);

#define	LINELEN		255

/*------------------------------------------------------------------------
 * main - UDP client for ECHO service
 *------------------------------------------------------------------------
 */
int
main(int argc, char *argv[])
{
	char	*host = "localhost";
	char	*service = "echo";

	switch (argc) {
	case 1:
		host = "localhost";
		break;
	case 3:
		service = argv[2];
		/* FALL THROUGH */
	case 2:
		host = argv[1];
		break;
	default:
		fprintf(stderr, "usage: UDPecho [host [port]]\n");
		exit(1);
	}
	UDPecho(host, service);
	exit(0);
}

/*------------------------------------------------------------------------
 * UDPecho - send input to ECHO service on specified host and print reply
 *------------------------------------------------------------------------
 */
int
UDPecho(const char *host, const char *service)
{
	char	buf[LINELEN+1];		/* buffer for one line of text	*/
	int	s, nchars;		/* socket descriptor, read count*/
	
	int i;
	
	/* to measure response time */
	struct timeval t1;
	struct timeval t2;
	double totalTime;

	s = connectUDP(host, service);

	while (fgets(buf, sizeof(buf), stdin)) {
		buf[LINELEN] = '\0';	/* insure null-terminated */
		nchars = strlen(buf);
		
		totalTime = 0;
		
		/* send the string 10 times to echo server */
		for(i=0; i<10; i++) {
			
			gettimeofday(&t1, 0);   /* measure the start time */
			
			(void) write(s, buf, nchars);

			if (read(s, buf, nchars) < 0)
				errexit("socket read failed: %s\n",
					strerror(errno));
			
			gettimeofday(&t2, 0); 	/*  measure the end time */
			
			/* calculate the cumulative RTT */
			totalTime += ( (t2.tv_sec*1000000 + t2.tv_usec) - (t1.tv_sec*1000000 + t1.tv_usec) );  				  
		} /* end for */
		
		fputs(buf, stdout);
		printf("RTT = %lf usec\n", totalTime/10);	
	}
	
}