EECS3150 - Client / Server Example

client.c

/* Program: client.c
 * A simple client to work with server.c program.
 * Host name and port used by server is to be
 * passed as arguments.
 *
 * To test: Open a terminal window.
 * At prompt ($ is my prompt symbol) you may
 * type the following as a test:
 *
 * $ ./client 192.168.0.12 54554
 * Please enter the message: EECS 3150 is fun!  
 * I got your message
 * $ 
 *
 */

#include <stdio.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\n", 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\n");
        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,&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\n",buffer);
    return 0;
}

server.c

/* Program: server.c
 * A simple server TCP sockets.
 * Server is executed before Client.
 * Port number is to be passed as an argument. 
 * 
 * To test: Open a terminal window.
 * At the prompt ($ is my prompt symbol) you may
 * type the following as a test:
 *
 * $ ./server 54554
 * Run client by providing host and port
 * Here is the message: EECS 3150 is fun!
 *
 * $
 */

#include <stdio.h>
#include <sys/types.h> 
#include <sys/socket.h>
#include <netinet/in.h>

int main(int argc, char *argv[])
{
     int sockfd, newsockfd, portno, clilen;
     char buffer[256];
     struct sockaddr_in serv_addr, cli_addr;
     int n;

     if( argc < 2 ) 
     {
        fprintf(stderr,"ERROR, no port provided\n");
        exit(1);
     }
     fprintf(stdout, "Run client by providing host and port\n");
     sockfd = socket(AF_INET, SOCK_STREAM, 0);
     if (sockfd < 0) 
        error("ERROR opening socket");
     bzero((char *) &serv_addr, sizeof(serv_addr));
     portno = atoi(argv[1]);
     serv_addr.sin_family = AF_INET;
     serv_addr.sin_addr.s_addr = INADDR_ANY;
     serv_addr.sin_port = htons(portno);
     if (bind(sockfd, (struct sockaddr *) &serv_addr,
              sizeof(serv_addr)) < 0) 
              error("ERROR on binding");
     listen(sockfd,5);
     clilen = sizeof(cli_addr);
     newsockfd = accept(sockfd, 
                 (struct sockaddr *) &cli_addr, 
                 &clilen);
     if( newsockfd < 0 ) 
         error("ERROR on accept");
     bzero(buffer,256);
     n = read(newsockfd,buffer,255);
     if( n < 0 ) 
       error("ERROR reading from socket");
     printf("Here is the message: %s\n",buffer);
     n = write(newsockfd,"I got your message",18);
     if( n < 0 ) 
       error("ERROR writing to socket");
     return 0; 
}

void error( char *msg )
{
  perror(msg);
  exit(1);
}