The Server

• A simple server is somewhat more complex.
• The socket needs to be grabbed again.
• The next step is to set a socket option
  • setsockopt
  • #include <sys/types.h>
  • #include <sys/socket.h>
  • Parameters:
    • The socket
    • A level, which in this case is SOL_SOCKET
    • The name of the option, in this case is is SO_REUSEADDR
      • This allows us to re-use the local address
    • A pointer to the values to set the value to
    • The length of the pointer.

      int val;
      
      val = 1;
      if (setsockopt(s, SOL_SOCKET, SO_REUSEADDR, &val, sizeof(val)) == -1) {
          perror("Setsocketopt failed ");
          exit(-1);
      }
      	    

    • There are many more of these options
  • The next step is to bind a name to a socket.
  • bind
    • #include <sys/types.h>
    • #include <sys/socket.h>
    • parameters
      • The socket
      • The sockaddr struct pointer as in connect
      • The length of the field.

      where.sin_addr.s_addr = INADDR_ANY;
      where.sin_port = htons(5600);
      where.sin_family = AF_INET;
      
      if (bind(s,(struct sockaddr *) &where, sizeof(where)) == -1) {
            perror("Bind of socket failed");
            exit(-1);
      }
      	    

  • Next we must listen
  • listen
    • #include <sys/socket.h>
    • parameters
      • The socket
      • a maximum length of the queue of pending connections.

      if (listen(s, 5) == -1) {
            perror("Listen Failed ");
            exit(-1);
      }
      	    

  • The socket is now setup, we can now service multiple connections
  • accept
    • Accepts a connection.
    • #include <sys/types.h>
    • #include <sys/socket.h>
    • Takes the socket
    • and a pointer to an addr struct (as in connect, and bind) , which is an address structure, which is filled in with information about the connection.
    • and the length of the addr struct
      • The length field should be filled in before the call.
    • Return is an int, a file descriptor.
    • If it is -1, then there is a problem.

      sotlen = sizeof(sot);
      while (( ns = accept(s,&sot, &sotlen)) != -1) {
      }
      	     

• My server code.