client.c

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>

void error(char *msg){
	perror(msg);
  	exit(0);
}
int main(int argc, char *argv[]){
  	int sockfd, portno, n;
  	struct sockaddr_in serv_addr;
  	struct hostent *server;
  	char buffer[256]; 
  	if (argc < 3){
  		fprintf(stderr,"usage %s hostname port", argv[0]);
  		exit(0);
  	}
  	portno = atoi(argv[2]);
  	sockfd = socket(AF_INET, SOCK_STREAM, 0); 
  	if (sockfd < 0)
  		error("ERROR opening socket");
	server=gethostbyname(argv[1]);
	if (server == NULL)
	{
  		fprintf(stderr,"ERROR, no such host");
  		exit(0);
	}
  	bzero((char *) &serv_addr, sizeof(serv_addr));
	serv_addr.sin_family = AF_INET;
	bcopy((char *)server->h_addr, (char *)&serv_addr.sin_addr.s_addr, server->h_length);
	serv_addr.sin_port=htons(portno);
	if(connect(sockfd,(struct sockaddr *) &serv_addr,sizeof(serv_addr)) < 0)
		error("error connecting");
	printf("Please enter the message: ");
  	bzero(buffer,256);
  	fgets(buffer,255,stdin);
  	n = write(sockfd,buffer,strlen(buffer));
  	if (n < 0)
    		error("ERROR writing to socket");
  	bzero(buffer,256);
  	n = read(sockfd,buffer,255);
  	if (n < 0)
    		error("ERROR reading from socket");
	printf("%s",buffer);
  	return 0;
}