12/31   When my program binds a socket to a port but dies due to an
        error, how do I "unbind" the socket so I can run the program
        again without getting "Address already in use"?  Thanks.
        \_ Man setsockopt, and look at SO_REUSEADDR
        \_ You will probably need something like this:
                int setReuseAddr(int listenfd) {
                  int on = 1, ret = 0;
                  if (setsockopt(listenfd,SOL_SOCKET,SO_REUSEADDR,
                                (void *)&on,sizeof(on)) < 0) {
                        close(listenfd);
                        ret = -1;
                  }
                  return ret;
                }