zeroconf.py 文件源码

def new_socket():
    s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)

    # SO_REUSEADDR should be equivalent to SO_REUSEPORT for
    # multicast UDP sockets (p 731, "TCP/IP Illustrated,
    # Volume 2"), but some BSD-derived systems require
    # SO_REUSEPORT to be specified explicity.  Also, not all
    # versions of Python have SO_REUSEPORT available.
    # Catch OSError and socket.error for kernel versions <3.9 because lacking
    # SO_REUSEPORT support.
    try:
        reuseport = socket.SO_REUSEPORT
    except AttributeError:
        pass
    else:
        try:
            s.setsockopt(socket.SOL_SOCKET, reuseport, 1)
        except (OSError, socket.error) as err:
            # OSError on python 3, socket.error on python 2
            if not err.errno == errno.ENOPROTOOPT:
                raise

    # OpenBSD needs the ttl and loop values for the IP_MULTICAST_TTL and
    # IP_MULTICAST_LOOP socket options as an unsigned char.
    ttl = struct.pack(b'B', 255)
    s.setsockopt(socket.IPPROTO_IP, socket.IP_MULTICAST_TTL, ttl)
    loop = struct.pack(b'B', 1)
    s.setsockopt(socket.IPPROTO_IP, socket.IP_MULTICAST_LOOP, loop)

    s.bind(('', _MDNS_PORT))
    return s