Programming

int main(int argc, char *argv[])
{
     int srvrSock;                        /* Socket descriptor for server */
     int clntSock;                        /* Socket descriptor for client */
     struct sockaddr_in echoServAddr;     /* Local address */
     struct sockaddr_in echoClntAddr;     /* Client address */
     unsigned short echoServPort;         /* Server port */
     unsigned int cliAddrLen;             /* Length of incoming message */
     int pid;
     struct sigaction sa;
     int loop;

     char ip[16];

     /* Test for correct number of parameters */
     if (argc < 2) {
         fprintf(stderr,"Verwendung:  %s <TCP SERVER PORT>\n", argv[0]);
         exit(1);
     }
     //end if

     /* First arg:  local port */
     echoServPort = atoi(argv[1]);

     /* Create socket for sending/receiving */
     if ((srvrSock = socket(AF_INET, SOCK_STREAM, 0)) < 0)
         DieWithError("socket() failed");
     //end if

     /* Construct local address structure */
     memset(&echoServAddr, 0, sizeof(echoServAddr));   /* Zero out 
structure */
     echoServAddr.sin_family = AF_INET;                /* Internet 
address family */
     echoServAddr.sin_addr.s_addr = htonl(INADDR_ANY); /* Any incoming 
interface */
     echoServAddr.sin_port = htons(echoServPort);      /* Local port */

     /* Bind to the local address */
     if (bind(srvrSock, (struct sockaddr *) &echoServAddr, 
sizeof(echoServAddr)) < 0)
         DieWithError("ERROR on binding");
     //end if

     /* Listen */
     if (listen(srvrSock,5)<0)
         DieWithError("listen() failed");
     //end if

     sa.sa_handler = sigchld_handler; // reap all dead processes
     sigemptyset(&sa.sa_mask);
     sa.sa_flags = SA_RESTART;
     if (sigaction(SIGCHLD, &sa, NULL) == -1) {
         perror("sigaction");
         exit(1);
     }


     /* Set the size of the in-out parameter */
     cliAddrLen = sizeof(echoClntAddr);

     while (1) {
         printf(" loop %d \n\n", loop);
         loop++;

         /* Wait for a client to connect */
         if ((clntSock = accept(srvrSock, (struct sockaddr *) 
&echoClntAddr, &cliAddrLen)) < 0)
             DieWithError("accept() failed");
         //end if

         /* clntSock is connected to a client! */
         strcpy(ip,inet_ntoa(echoClntAddr.sin_addr));
         printf("Handling client %s\n", ip);

         pid = fork();
         if (pid < 0)
         {
         DieWithError("ERROR on fork");
         }
         else if (pid == 0)
         {
             close(srvrSock);
             dostuff(clntSock,ip);
             close(clntSock);
             exit(0);
         }
         else close(clntSock);

     } /* end of while */

     return 0; /* we never get here */
}