TCP Server Hello World example

07 Dec 2011

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

#define pexit(s) ({perror(s); exit(EXIT_FAILURE);})

#define BUFLEN 0x400
static char buf[BUFLEN];

int main(int argc, char **argv)
{
 int srv_sock;
 int cli_sock;
 int srv_addr_len;
 int cli_addr_len;
 int error;
 int nbytes; 
 struct sockaddr_in srv_addr;
 struct sockaddr_in cli_addr;

  
 if (argc <= 1) { 
  printf("Usage: %s PORT\n", argv[0]);
  exit(EXIT_FAILURE);
 }

 srv_sock = socket(PF_INET, SOCK_STREAM, 0);
 if (srv_sock < 0)
  pexit("socket");


        srv_addr_len = sizeof(srv_addr);
        bzero(&srv_addr, srv_addr_len);
        srv_addr.sin_addr.s_addr = htonl(INADDR_ANY);
 srv_addr.sin_family = PF_INET;
 srv_addr.sin_port = htons(atoi(argv[1]));

        error = bind(srv_sock, (struct sockaddr *)&srv_addr, srv_addr_len);
        if (error)
                pexit("bind");

        error = listen(srv_sock, 5);
        if (error)
                pexit("listen");

        cli_addr_len = sizeof(cli_addr);
        while ((cli_sock = accept(srv_sock, (struct sockaddr *)&cli_addr,
                                        &cli_addr_len)) != -1) 
        {
                printf("Received connection from %s\n",
                                inet_ntoa(cli_addr.sin_addr.s_addr));

                nbytes = send(cli_sock, "Hello World\n", strlen("Hello World\n"), 0);
                if (nbytes == -1)
                        perror("send");
                close(cli_sock);
 } 

 close(srv_sock);
 return 0;
}