Addrinfo#ip_port

static VALUE
addrinfo_ip_port(VALUE self)
{
    rb_addrinfo_t *rai = get_addrinfo(self);
    int family = ai_get_afamily(rai);
    int port;

    if (!IS_IP_FAMILY(family)) {
      bad_family:
#ifdef AF_INET6
        rb_raise(rb_eSocket, "need IPv4 or IPv6 address");
#else
        rb_raise(rb_eSocket, "need IPv4 address");
#endif
    }

    switch (family) {
      case AF_INET:
        if (rai->sockaddr_len != sizeof(struct sockaddr_in))
            rb_raise(rb_eSocket, "unexpected sockaddr size for IPv4");
        port = ntohs(rai->addr.in.sin_port);
        break;

#ifdef AF_INET6
      case AF_INET6:
        if (rai->sockaddr_len != sizeof(struct sockaddr_in6))
            rb_raise(rb_eSocket, "unexpected sockaddr size for IPv6");
        port = ntohs(rai->addr.in6.sin6_port);
        break;
#endif

      default:
        goto bad_family;
    }

    return INT2NUM(port);
}