获取空闲端口

时间：2010-10-15 来源：happy1123

int get_free_port()
{
  int port = 0;
int fd = -1;
socklen_t = 0;
port = -1;

#ifndef AF_IPV6
  struct sockaddr_in sin;
  memset(&sin, 0, sizeof(sin));
  sin.sin_family = AF_INET;
  sin.sin_port = htons(0);
  sin.sin_addr.s_addr = htonl(INADDR_ANY);

fd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);

  if(fd < 0){
      printf("socket() error:%s\n", strerror(errno));
      return -1;
  }

  if(bind(fd, (struct sockaddr *)&sin, sizeof(sin)) != 0)
  {
      printf("bind() error:%s\n", strerror(errno));
      close(fd);
      return -1;
  }

len = sizeof(sin);
  if(getsockname(fd, (struct sockaddr *)&sin, &len) != 0)
  {
      printf("getsockname() error:%s\n", strerror(errno));
      close(fd);
      return -1;
  }

port = sin.sin_port;
  if(fd != -1)
      close(fd);

#else
  struct sockaddr_in6 sin6;
  memset(&sin6, 0, sizeof(sin6));
  sin.sin_family = AF_INET6;
  sin.sin_port = htons(0);
sin6.sin_addr.s_addr = htonl(IN6ADDR_ANY);

fd = socket(AF_INET6, SOCK_STREAM, IPPROTO_TCP);

  if(fd < 0){
      printf("socket() error:%s\n", strerror(errno));
      return -1;
  }

  if(bind(fd, (struct sockaddr *)&sin6, sizeof(sin6)) != 0)
  {
      printf("bind() error:%s\n", strerror(errno));
      close(fd);
      return -1;
  }

len = sizeof(sin6);
  if(getsockname(fd, (struct sockaddr *)&sin6, &len) != 0)
  {
      printf("getsockname() error:%s\n", strerror(errno));
      close(fd);
      return -1;
  }

port = sin6.sin6_port;

  if(fd != -1)
      close(fd);

#endif
return port;
}