[c-prog] socket() ; SUCCESS but !!!

[Ahmed Shabana]

This server code runs well at its first run
but when I run it again it give me error in bind()

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

#define SERVER_ERROR(msg,exit_code) \
        do { fprintf(stderr,msg);exit(exit_code);}while(0)
#define BUF_SIZE 500

// This code will represent a simple server that can response to any
http request and load simple module called "MYMOD"
// This will take two args $ $PROGRAM_NAME SOCKET_NUMBER
int main( int argc, char* argv[])
{
        int sfd;
        char msg[100];
        struct addrinfo hints,*res;     

        if ( argc != 2){
                sprintf(msg,"USAGE: $%s PortNumber \n",argv[0]);
                SERVER_ERROR(msg,100);
        }
        // Create addr info data to use in socket() Creation
        hints.ai_family = AF_UNSPEC;
        hints.ai_socktype = SOCK_STREAM;
        hints.ai_protocol = 0;
        if ( getaddrinfo("localhost", "1111" ,&hints ,&res) )
                SERVER_ERROR("getaddrinfo",99);
        if ( (sfd = socket(res->ai_family, res->ai_socktype, res->ai_protocol)) 
== -1 )
                SERVER_ERROR("socket()",101);
        if ( bind(sfd, res->ai_addr, res->ai_addrlen) )
                SERVER_ERROR("bind()",102);
        freeaddrinfo(res);
        if ( listen(sfd ,5) )
                SERVER_ERROR("listen()",103);
        
        struct sockaddr_in cs;
        socklen_t slen;
        puts("WE ARE LISTENING NOW .....");
        if (accept(sfd ,&cs ,&slen) == -1)
                SERVER_ERROR("accept()",104);
        puts("Client trying to connect  now ...");
        close(sfd);
        return 0;
}