/*  * Copyright (c) 2000 by Matt Welsh and The Regents of the University of  * California. All rights reserved. * * Permission to use, copy, modify, and distribute this software and its * documentation for any purpose, without fee, and without written agreement is * hereby granted, provided that the above copyright notice and the following * two paragraphs appear in all copies of this software. *  * IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY FOR * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT * OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF THE UNIVERSITY OF * CALIFORNIA HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. *  * THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY WARRANTIES, * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY * AND FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS * ON AN "AS IS" BASIS, AND THE UNIVERSITY OF CALIFORNIA HAS NO OBLIGATION TO * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS. * * Author: Matt Welsh <mdw@cs.berkeley.edu> *  *//* This is a simple C test program which opens a nonblocking socket and * reads a sequence of packets from it. */#include <stdio.h>#include <errno.h>#include <string.h>#include <sys/types.h>#include <sys/socket.h>#include <sys/ioctl.h>#include <netinet/tcp.h>#include <netinet/in.h>#include <arpa/inet.h>#include <unistd.h>#include <fcntl.h>#undef NDEBUG#include <assert.h>#define PORT 4046void main() {  int fd;  int arg;  struct sockaddr_in him;  char buf[4096];  fd = socket(AF_INET, SOCK_STREAM, 0);  setsockopt(fd,SOL_SOCKET, SO_REUSEADDR, (char *)&arg, 4);  memset((char *)&him,  0, sizeof(him));  him.sin_port = htons((short)0);  him.sin_addr.s_addr = (unsigned long)htonl(INADDR_ANY);  him.sin_family = AF_INET;  assert(bind(fd, (struct sockaddr *)&him, sizeof(him)) >= 0);  memset((char *)&him,  0, sizeof(him));  him.sin_port = htons((short)PORT);  him.sin_addr.s_addr = (unsigned long)htonl(INADDR_LOOPBACK);  him.sin_family = AF_INET;  assert(connect(fd, (struct sockaddr *)&him, sizeof(him)) >= 0);  assert(fcntl(fd, F_SETFL, O_NONBLOCK) >= 0);  while (1) {    int n;    fprintf(stderr,"Reading...\n");    n = read(fd, buf, 4096);    if (n >= 0) {      fprintf(stderr,"Read %d bytes\n", n);    } else {      fprintf(stderr,"Got error: %d (errno=%d): %s\n", n, errno, strerror(errno));    }  }}