Python socket 模块，has_ipv6() 实例源码

def _has_ipv6(host):
    """ Returns True if the system can bind an IPv6 address. """
    sock = None
    has_ipv6 = False

    if socket.has_ipv6:
        # has_ipv6 returns true if cPython was compiled with IPv6 support.
        # It does not tell us if the system has IPv6 support enabled. To
        # determine that we must bind to an IPv6 address.
        # https://github.com/shazow/urllib3/pull/611
        # https://bugs.python.org/issue658327
        try:
            sock = socket.socket(socket.AF_INET6)
            sock.bind((host, 0))
            has_ipv6 = True
        except Exception:
            pass

    if sock:
        sock.close()
    return has_ipv6

def _has_ipv6(host):
    """ Returns True if the system can bind an IPv6 address. """
    sock = None
    has_ipv6 = False

    if socket.has_ipv6:
        # has_ipv6 returns true if cPython was compiled with IPv6 support.
        # It does not tell us if the system has IPv6 support enabled. To
        # determine that we must bind to an IPv6 address.
        # https://github.com/shazow/urllib3/pull/611
        # https://bugs.python.org/issue658327
        try:
            sock = socket.socket(socket.AF_INET6)
            sock.bind((host, 0))
            has_ipv6 = True
        except Exception:
            pass

    if sock:
        sock.close()
    return has_ipv6

def _has_ipv6(host):
    """ Returns True if the system can bind an IPv6 address. """
    sock = None
    has_ipv6 = False

    if socket.has_ipv6:
        # has_ipv6 returns true if cPython was compiled with IPv6 support.
        # It does not tell us if the system has IPv6 support enabled. To
        # determine that we must bind to an IPv6 address.
        # https://github.com/shazow/urllib3/pull/611
        # https://bugs.python.org/issue658327
        try:
            sock = socket.socket(socket.AF_INET6)
            sock.bind((host, 0))
            has_ipv6 = True
        except Exception:
            pass

    if sock:
        sock.close()
    return has_ipv6

def _has_ipv6(host):
    """ Returns True if the system can bind an IPv6 address. """
    sock = None
    has_ipv6 = False

    if socket.has_ipv6:
        # has_ipv6 returns true if cPython was compiled with IPv6 support.
        # It does not tell us if the system has IPv6 support enabled. To
        # determine that we must bind to an IPv6 address.
        # https://github.com/shazow/urllib3/pull/611
        # https://bugs.python.org/issue658327
        try:
            sock = socket.socket(socket.AF_INET6)
            sock.bind((host, 0))
            has_ipv6 = True
        except Exception:
            pass

    if sock:
        sock.close()
    return has_ipv6

def _has_ipv6(host):
    """ Returns True if the system can bind an IPv6 address. """
    sock = None
    has_ipv6 = False

    if socket.has_ipv6:
        # has_ipv6 returns true if cPython was compiled with IPv6 support.
        # It does not tell us if the system has IPv6 support enabled. To
        # determine that we must bind to an IPv6 address.
        # https://github.com/shazow/urllib3/pull/611
        # https://bugs.python.org/issue658327
        try:
            sock = socket.socket(socket.AF_INET6)
            sock.bind((host, 0))
            has_ipv6 = True
        except Exception:
            pass

    if sock:
        sock.close()
    return has_ipv6

def _has_ipv6(host):
    """ Returns True if the system can bind an IPv6 address. """
    sock = None
    has_ipv6 = False

    if socket.has_ipv6:
        # has_ipv6 returns true if cPython was compiled with IPv6 support.
        # It does not tell us if the system has IPv6 support enabled. To
        # determine that we must bind to an IPv6 address.
        # https://github.com/shazow/urllib3/pull/611
        # https://bugs.python.org/issue658327
        try:
            sock = socket.socket(socket.AF_INET6)
            sock.bind((host, 0))
            has_ipv6 = True
        except Exception:
            pass

    if sock:
        sock.close()
    return has_ipv6

def _has_ipv6(host):
    """ Returns True if the system can bind an IPv6 address. """
    sock = None
    has_ipv6 = False

    if socket.has_ipv6:
        # has_ipv6 returns true if cPython was compiled with IPv6 support.
        # It does not tell us if the system has IPv6 support enabled. To
        # determine that we must bind to an IPv6 address.
        # https://github.com/shazow/urllib3/pull/611
        # https://bugs.python.org/issue658327
        try:
            sock = socket.socket(socket.AF_INET6)
            sock.bind((host, 0))
            has_ipv6 = True
        except Exception:
            pass

    if sock:
        sock.close()
    return has_ipv6

def _has_ipv6(host):
    """ Returns True if the system can bind an IPv6 address. """
    sock = None
    has_ipv6 = False

    if socket.has_ipv6:
        # has_ipv6 returns true if cPython was compiled with IPv6 support.
        # It does not tell us if the system has IPv6 support enabled. To
        # determine that we must bind to an IPv6 address.
        # https://github.com/shazow/urllib3/pull/611
        # https://bugs.python.org/issue658327
        try:
            sock = socket.socket(socket.AF_INET6)
            sock.bind((host, 0))
            has_ipv6 = True
        except Exception:
            pass

    if sock:
        sock.close()
    return has_ipv6

def _has_ipv6(host):
    """ Returns True if the system can bind an IPv6 address. """
    sock = None
    has_ipv6 = False

    if socket.has_ipv6:
        # has_ipv6 returns true if cPython was compiled with IPv6 support.
        # It does not tell us if the system has IPv6 support enabled. To
        # determine that we must bind to an IPv6 address.
        # https://github.com/shazow/urllib3/pull/611
        # https://bugs.python.org/issue658327
        try:
            sock = socket.socket(socket.AF_INET6)
            sock.bind((host, 0))
            has_ipv6 = True
        except Exception:
            pass

    if sock:
        sock.close()
    return has_ipv6

def _has_ipv6(host):
    """ Returns True if the system can bind an IPv6 address. """
    sock = None
    has_ipv6 = False

    if socket.has_ipv6:
        # has_ipv6 returns true if cPython was compiled with IPv6 support.
        # It does not tell us if the system has IPv6 support enabled. To
        # determine that we must bind to an IPv6 address.
        # https://github.com/shazow/urllib3/pull/611
        # https://bugs.python.org/issue658327
        try:
            sock = socket.socket(socket.AF_INET6)
            sock.bind((host, 0))
            has_ipv6 = True
        except Exception:
            pass

    if sock:
        sock.close()
    return has_ipv6

def _has_ipv6(host):
    """ Returns True if the system can bind an IPv6 address. """
    sock = None
    has_ipv6 = False

    if socket.has_ipv6:
        # has_ipv6 returns true if cPython was compiled with IPv6 support.
        # It does not tell us if the system has IPv6 support enabled. To
        # determine that we must bind to an IPv6 address.
        # https://github.com/shazow/urllib3/pull/611
        # https://bugs.python.org/issue658327
        try:
            sock = socket.socket(socket.AF_INET6)
            sock.bind((host, 0))
            has_ipv6 = True
        except Exception:
            pass

    if sock:
        sock.close()
    return has_ipv6

def _has_ipv6(host):
    """ Returns True if the system can bind an IPv6 address. """
    sock = None
    has_ipv6 = False

    if socket.has_ipv6:
        # has_ipv6 returns true if cPython was compiled with IPv6 support.
        # It does not tell us if the system has IPv6 support enabled. To
        # determine that we must bind to an IPv6 address.
        # https://github.com/shazow/urllib3/pull/611
        # https://bugs.python.org/issue658327
        try:
            sock = socket.socket(socket.AF_INET6)
            sock.bind((host, 0))
            has_ipv6 = True
        except Exception:
            pass

    if sock:
        sock.close()
    return has_ipv6

def _has_ipv6(host):
    """ Returns True if the system can bind an IPv6 address. """
    sock = None
    has_ipv6 = False

    if socket.has_ipv6:
        # has_ipv6 returns true if cPython was compiled with IPv6 support.
        # It does not tell us if the system has IPv6 support enabled. To
        # determine that we must bind to an IPv6 address.
        # https://github.com/shazow/urllib3/pull/611
        # https://bugs.python.org/issue658327
        try:
            sock = socket.socket(socket.AF_INET6)
            sock.bind((host, 0))
            has_ipv6 = True
        except Exception:
            pass

    if sock:
        sock.close()
    return has_ipv6

def _has_ipv6(host):
    """ Returns True if the system can bind an IPv6 address. """
    sock = None
    has_ipv6 = False

    if socket.has_ipv6:
        # has_ipv6 returns true if cPython was compiled with IPv6 support.
        # It does not tell us if the system has IPv6 support enabled. To
        # determine that we must bind to an IPv6 address.
        # https://github.com/shazow/urllib3/pull/611
        # https://bugs.python.org/issue658327
        try:
            sock = socket.socket(socket.AF_INET6)
            sock.bind((host, 0))
            has_ipv6 = True
        except Exception:
            pass

    if sock:
        sock.close()
    return has_ipv6

def _has_ipv6(host):
    """ Returns True if the system can bind an IPv6 address. """
    sock = None
    has_ipv6 = False

    if socket.has_ipv6:
        # has_ipv6 returns true if cPython was compiled with IPv6 support.
        # It does not tell us if the system has IPv6 support enabled. To
        # determine that we must bind to an IPv6 address.
        # https://github.com/shazow/urllib3/pull/611
        # https://bugs.python.org/issue658327
        try:
            sock = socket.socket(socket.AF_INET6)
            sock.bind((host, 0))
            has_ipv6 = True
        except Exception:
            pass

    if sock:
        sock.close()
    return has_ipv6

def _has_ipv6(host):
    """ Returns True if the system can bind an IPv6 address. """
    sock = None
    has_ipv6 = False

    if socket.has_ipv6:
        # has_ipv6 returns true if cPython was compiled with IPv6 support.
        # It does not tell us if the system has IPv6 support enabled. To
        # determine that we must bind to an IPv6 address.
        # https://github.com/shazow/urllib3/pull/611
        # https://bugs.python.org/issue658327
        try:
            sock = socket.socket(socket.AF_INET6)
            sock.bind((host, 0))
            has_ipv6 = True
        except Exception:
            pass

    if sock:
        sock.close()
    return has_ipv6

def _has_ipv6(host):
    """ Returns True if the system can bind an IPv6 address. """
    sock = None
    has_ipv6 = False

    if socket.has_ipv6:
        # has_ipv6 returns true if cPython was compiled with IPv6 support.
        # It does not tell us if the system has IPv6 support enabled. To
        # determine that we must bind to an IPv6 address.
        # https://github.com/shazow/urllib3/pull/611
        # https://bugs.python.org/issue658327
        try:
            sock = socket.socket(socket.AF_INET6)
            sock.bind((host, 0))
            has_ipv6 = True
        except Exception:
            pass

    if sock:
        sock.close()
    return has_ipv6

def _has_ipv6(host):
    """ Returns True if the system can bind an IPv6 address. """
    sock = None
    has_ipv6 = False

    if socket.has_ipv6:
        # has_ipv6 returns true if cPython was compiled with IPv6 support.
        # It does not tell us if the system has IPv6 support enabled. To
        # determine that we must bind to an IPv6 address.
        # https://github.com/shazow/urllib3/pull/611
        # https://bugs.python.org/issue658327
        try:
            sock = socket.socket(socket.AF_INET6)
            sock.bind((host, 0))
            has_ipv6 = True
        except Exception:
            pass

    if sock:
        sock.close()
    return has_ipv6

def _has_ipv6(host):
    """ Returns True if the system can bind an IPv6 address. """
    sock = None
    has_ipv6 = False

    if socket.has_ipv6:
        # has_ipv6 returns true if cPython was compiled with IPv6 support.
        # It does not tell us if the system has IPv6 support enabled. To
        # determine that we must bind to an IPv6 address.
        # https://github.com/shazow/urllib3/pull/611
        # https://bugs.python.org/issue658327
        try:
            sock = socket.socket(socket.AF_INET6)
            sock.bind((host, 0))
            has_ipv6 = True
        except Exception:
            pass

    if sock:
        sock.close()
    return has_ipv6

def _has_ipv6(host):
    """ Returns True if the system can bind an IPv6 address. """
    sock = None
    has_ipv6 = False

    if socket.has_ipv6:
        # has_ipv6 returns true if cPython was compiled with IPv6 support.
        # It does not tell us if the system has IPv6 support enabled. To
        # determine that we must bind to an IPv6 address.
        # https://github.com/shazow/urllib3/pull/611
        # https://bugs.python.org/issue658327
        try:
            sock = socket.socket(socket.AF_INET6)
            sock.bind((host, 0))
            has_ipv6 = True
        except Exception:
            pass

    if sock:
        sock.close()
    return has_ipv6

def _has_ipv6(host):
    """ Returns True if the system can bind an IPv6 address. """
    sock = None
    has_ipv6 = False

    if socket.has_ipv6:
        # has_ipv6 returns true if cPython was compiled with IPv6 support.
        # It does not tell us if the system has IPv6 support enabled. To
        # determine that we must bind to an IPv6 address.
        # https://github.com/shazow/urllib3/pull/611
        # https://bugs.python.org/issue658327
        try:
            sock = socket.socket(socket.AF_INET6)
            sock.bind((host, 0))
            has_ipv6 = True
        except Exception:
            pass

    if sock:
        sock.close()
    return has_ipv6

def _has_ipv6(host):
    """ Returns True if the system can bind an IPv6 address. """
    sock = None
    has_ipv6 = False

    if socket.has_ipv6:
        # has_ipv6 returns true if cPython was compiled with IPv6 support.
        # It does not tell us if the system has IPv6 support enabled. To
        # determine that we must bind to an IPv6 address.
        # https://github.com/shazow/urllib3/pull/611
        # https://bugs.python.org/issue658327
        try:
            sock = socket.socket(socket.AF_INET6)
            sock.bind((host, 0))
            has_ipv6 = True
        except Exception:
            pass

    if sock:
        sock.close()
    return has_ipv6

def _has_ipv6(host):
    """ Returns True if the system can bind an IPv6 address. """
    sock = None
    has_ipv6 = False

    if socket.has_ipv6:
        # has_ipv6 returns true if cPython was compiled with IPv6 support.
        # It does not tell us if the system has IPv6 support enabled. To
        # determine that we must bind to an IPv6 address.
        # https://github.com/shazow/urllib3/pull/611
        # https://bugs.python.org/issue658327
        try:
            sock = socket.socket(socket.AF_INET6)
            sock.bind((host, 0))
            has_ipv6 = True
        except Exception:
            pass

    if sock:
        sock.close()
    return has_ipv6

def _has_ipv6(host):
    """ Returns True if the system can bind an IPv6 address. """
    sock = None
    has_ipv6 = False

    if socket.has_ipv6:
        # has_ipv6 returns true if cPython was compiled with IPv6 support.
        # It does not tell us if the system has IPv6 support enabled. To
        # determine that we must bind to an IPv6 address.
        # https://github.com/shazow/urllib3/pull/611
        # https://bugs.python.org/issue658327
        try:
            sock = socket.socket(socket.AF_INET6)
            sock.bind((host, 0))
            has_ipv6 = True
        except Exception:
            pass

    if sock:
        sock.close()
    return has_ipv6

def _has_ipv6(host):
    """ Returns True if the system can bind an IPv6 address. """
    sock = None
    has_ipv6 = False

    if socket.has_ipv6:
        # has_ipv6 returns true if cPython was compiled with IPv6 support.
        # It does not tell us if the system has IPv6 support enabled. To
        # determine that we must bind to an IPv6 address.
        # https://github.com/shazow/urllib3/pull/611
        # https://bugs.python.org/issue658327
        try:
            sock = socket.socket(socket.AF_INET6)
            sock.bind((host, 0))
            has_ipv6 = True
        except Exception:
            pass

    if sock:
        sock.close()
    return has_ipv6

def _has_ipv6(host):
    """ Returns True if the system can bind an IPv6 address. """
    sock = None
    has_ipv6 = False

    if socket.has_ipv6:
        # has_ipv6 returns true if cPython was compiled with IPv6 support.
        # It does not tell us if the system has IPv6 support enabled. To
        # determine that we must bind to an IPv6 address.
        # https://github.com/shazow/urllib3/pull/611
        # https://bugs.python.org/issue658327
        try:
            sock = socket.socket(socket.AF_INET6)
            sock.bind((host, 0))
            has_ipv6 = True
        except Exception:
            pass

    if sock:
        sock.close()
    return has_ipv6

def _has_ipv6(host):
    """ Returns True if the system can bind an IPv6 address. """
    sock = None
    has_ipv6 = False

    if socket.has_ipv6:
        # has_ipv6 returns true if cPython was compiled with IPv6 support.
        # It does not tell us if the system has IPv6 support enabled. To
        # determine that we must bind to an IPv6 address.
        # https://github.com/shazow/urllib3/pull/611
        # https://bugs.python.org/issue658327
        try:
            sock = socket.socket(socket.AF_INET6)
            sock.bind((host, 0))
            has_ipv6 = True
        except Exception:
            pass

    if sock:
        sock.close()
    return has_ipv6

def _has_ipv6(host):
    """ Returns True if the system can bind an IPv6 address. """
    sock = None
    has_ipv6 = False

    if socket.has_ipv6:
        # has_ipv6 returns true if cPython was compiled with IPv6 support.
        # It does not tell us if the system has IPv6 support enabled. To
        # determine that we must bind to an IPv6 address.
        # https://github.com/shazow/urllib3/pull/611
        # https://bugs.python.org/issue658327
        try:
            sock = socket.socket(socket.AF_INET6)
            sock.bind((host, 0))
            has_ipv6 = True
        except Exception:
            pass

    if sock:
        sock.close()
    return has_ipv6

def _has_ipv6(host):
    """ Returns True if the system can bind an IPv6 address. """
    sock = None
    has_ipv6 = False

    if socket.has_ipv6:
        # has_ipv6 returns true if cPython was compiled with IPv6 support.
        # It does not tell us if the system has IPv6 support enabled. To
        # determine that we must bind to an IPv6 address.
        # https://github.com/shazow/urllib3/pull/611
        # https://bugs.python.org/issue658327
        try:
            sock = socket.socket(socket.AF_INET6)
            sock.bind((host, 0))
            has_ipv6 = True
        except Exception:
            pass

    if sock:
        sock.close()
    return has_ipv6

def __init__(self, host, port, handler):
        threading.Thread.__init__(self, name="COAPThread")
        self.handler = COAPHandler(handler)
        self.host = host
        self.port = port
        self.multicast_ip = '224.0.1.123'
        if socket.has_ipv6:
            address_family = socket.AF_INET6
        else:
            address_family = socket.AF_INET
        try:
            self.socket = socket.socket(address_family, socket.SOCK_DGRAM)
        except:
            self.socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
        self.socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
        self.socket.bind(('', port))
        self.socket.settimeout(3)
        self.running = True
        self.start()

def _has_ipv6(host):
    """ Returns True if the system can bind an IPv6 address. """
    sock = None
    has_ipv6 = False

    if socket.has_ipv6:
        # has_ipv6 returns true if cPython was compiled with IPv6 support.
        # It does not tell us if the system has IPv6 support enabled. To
        # determine that we must bind to an IPv6 address.
        # https://github.com/shazow/urllib3/pull/611
        # https://bugs.python.org/issue658327
        try:
            sock = socket.socket(socket.AF_INET6)
            sock.bind((host, 0))
            has_ipv6 = True
        except Exception:
            pass

    if sock:
        sock.close()
    return has_ipv6

def extract_ipv6_info():
    """ Extracts IPv6 information"""
    print ("IPv6 support built into Python: %s" %socket.has_ipv6)
    for interface in ni.interfaces():
        all_addresses = ni.ifaddresses(interface)
        print ("Interface %s:" %interface)
        for family,addrs in all_addresses.items():
            fam_name = ni.address_families[family]

            for addr in addrs:
                if fam_name == 'AF_INET6':
                    addr = addr['addr']
                    has_eth_string = addr.split("%eth")
                    if has_eth_string:
                        addr = addr.split("%eth")[0]
                    try:
                        print ("    IP Address: %s" %na.IPNetwork(addr))
                        print ("    IP Version: %s" %na.IPNetwork(addr).version)
                        print ("    IP Prefix length: %s" %na.IPNetwork(addr).prefixlen)
                        print ("    Network: %s" %na.IPNetwork(addr).network)
                        print ("    Broadcast: %s" %na.IPNetwork(addr).broadcast)
                    except Exception as e:
                        print ("Skip Non-IPv6 Interface")

def inspect_ipv6_support():
    """ Find the ipv6 address"""
    print ("IPV6 support built into Python: %s" %socket.has_ipv6)
    ipv6_addr = {}
    for interface in ni.interfaces():
        all_addresses = ni.ifaddresses(interface)
        print ("Interface %s:" %interface)

        for family,addrs in all_addresses.items():
            fam_name = ni.address_families[family]
            print ('  Address family: %s' % fam_name)
            for addr in addrs:
                if fam_name == 'AF_INET6':
                    ipv6_addr[interface] = addr['addr']
                print ('    Address  : %s' % addr['addr'])
                nmask = addr.get('netmask', None)
                if nmask:
                    print ('    Netmask  : %s' % nmask)
                bcast = addr.get('broadcast', None)
                if bcast:
                    print ('    Broadcast: %s' % bcast)
    if ipv6_addr:
        print ("Found IPv6 address: %s" %ipv6_addr)
    else:
        print ("No IPv6 interface found!")

def _has_ipv6(host):
    """ Returns True if the system can bind an IPv6 address. """
    sock = None
    has_ipv6 = False

    if socket.has_ipv6:
        # has_ipv6 returns true if cPython was compiled with IPv6 support.
        # It does not tell us if the system has IPv6 support enabled. To
        # determine that we must bind to an IPv6 address.
        # https://github.com/shazow/urllib3/pull/611
        # https://bugs.python.org/issue658327
        try:
            sock = socket.socket(socket.AF_INET6)
            sock.bind((host, 0))
            has_ipv6 = True
        except Exception:
            pass

    if sock:
        sock.close()
    return has_ipv6

def _has_ipv6(host):
    """ Returns True if the system can bind an IPv6 address. """
    sock = None
    has_ipv6 = False

    if socket.has_ipv6:
        # has_ipv6 returns true if cPython was compiled with IPv6 support.
        # It does not tell us if the system has IPv6 support enabled. To
        # determine that we must bind to an IPv6 address.
        # https://github.com/shazow/urllib3/pull/611
        # https://bugs.python.org/issue658327
        try:
            sock = socket.socket(socket.AF_INET6)
            sock.bind((host, 0))
            has_ipv6 = True
        except Exception:
            pass

    if sock:
        sock.close()
    return has_ipv6

def _has_ipv6(host):
    """ Returns True if the system can bind an IPv6 address. """
    sock = None
    has_ipv6 = False

    if socket.has_ipv6:
        # has_ipv6 returns true if cPython was compiled with IPv6 support.
        # It does not tell us if the system has IPv6 support enabled. To
        # determine that we must bind to an IPv6 address.
        # https://github.com/shazow/urllib3/pull/611
        # https://bugs.python.org/issue658327
        try:
            sock = socket.socket(socket.AF_INET6)
            sock.bind((host, 0))
            has_ipv6 = True
        except Exception:
            pass

    if sock:
        sock.close()
    return has_ipv6

def _has_ipv6(host):
    """ Returns True if the system can bind an IPv6 address. """
    sock = None
    has_ipv6 = False

    if socket.has_ipv6:
        # has_ipv6 returns true if cPython was compiled with IPv6 support.
        # It does not tell us if the system has IPv6 support enabled. To
        # determine that we must bind to an IPv6 address.
        # https://github.com/shazow/urllib3/pull/611
        # https://bugs.python.org/issue658327
        try:
            sock = socket.socket(socket.AF_INET6)
            sock.bind((host, 0))
            has_ipv6 = True
        except Exception:
            pass

    if sock:
        sock.close()
    return has_ipv6

def _has_ipv6(host):
    """ Returns True if the system can bind an IPv6 address. """
    sock = None
    has_ipv6 = False

    if socket.has_ipv6:
        # has_ipv6 returns true if cPython was compiled with IPv6 support.
        # It does not tell us if the system has IPv6 support enabled. To
        # determine that we must bind to an IPv6 address.
        # https://github.com/shazow/urllib3/pull/611
        # https://bugs.python.org/issue658327
        try:
            sock = socket.socket(socket.AF_INET6)
            sock.bind((host, 0))
            has_ipv6 = True
        except Exception:
            pass

    if sock:
        sock.close()
    return has_ipv6

def _has_ipv6(host):
    """ Returns True if the system can bind an IPv6 address. """
    sock = None
    has_ipv6 = False

    if socket.has_ipv6:
        # has_ipv6 returns true if cPython was compiled with IPv6 support.
        # It does not tell us if the system has IPv6 support enabled. To
        # determine that we must bind to an IPv6 address.
        # https://github.com/shazow/urllib3/pull/611
        # https://bugs.python.org/issue658327
        try:
            sock = socket.socket(socket.AF_INET6)
            sock.bind((host, 0))
            has_ipv6 = True
        except Exception:
            pass

    if sock:
        sock.close()
    return has_ipv6

def _has_ipv6(host):
    """ Returns True if the system can bind an IPv6 address. """
    sock = None
    has_ipv6 = False

    if socket.has_ipv6:
        # has_ipv6 returns true if cPython was compiled with IPv6 support.
        # It does not tell us if the system has IPv6 support enabled. To
        # determine that we must bind to an IPv6 address.
        # https://github.com/shazow/urllib3/pull/611
        # https://bugs.python.org/issue658327
        try:
            sock = socket.socket(socket.AF_INET6)
            sock.bind((host, 0))
            has_ipv6 = True
        except Exception:
            pass

    if sock:
        sock.close()
    return has_ipv6

def _has_ipv6(host):
    """ Returns True if the system can bind an IPv6 address. """
    sock = None
    has_ipv6 = False

    if socket.has_ipv6:
        # has_ipv6 returns true if cPython was compiled with IPv6 support.
        # It does not tell us if the system has IPv6 support enabled. To
        # determine that we must bind to an IPv6 address.
        # https://github.com/shazow/urllib3/pull/611
        # https://bugs.python.org/issue658327
        try:
            sock = socket.socket(socket.AF_INET6)
            sock.bind((host, 0))
            has_ipv6 = True
        except Exception:
            pass

    if sock:
        sock.close()
    return has_ipv6

def _has_ipv6(host):
    """ Returns True if the system can bind an IPv6 address. """
    sock = None
    has_ipv6 = False

    if socket.has_ipv6:
        # has_ipv6 returns true if cPython was compiled with IPv6 support.
        # It does not tell us if the system has IPv6 support enabled. To
        # determine that we must bind to an IPv6 address.
        # https://github.com/shazow/urllib3/pull/611
        # https://bugs.python.org/issue658327
        try:
            sock = socket.socket(socket.AF_INET6)
            sock.bind((host, 0))
            has_ipv6 = True
        except Exception:
            pass

    if sock:
        sock.close()
    return has_ipv6

def _has_ipv6(host):
    """ Returns True if the system can bind an IPv6 address. """
    sock = None
    has_ipv6 = False

    if socket.has_ipv6:
        # has_ipv6 returns true if cPython was compiled with IPv6 support.
        # It does not tell us if the system has IPv6 support enabled. To
        # determine that we must bind to an IPv6 address.
        # https://github.com/shazow/urllib3/pull/611
        # https://bugs.python.org/issue658327
        try:
            sock = socket.socket(socket.AF_INET6)
            sock.bind((host, 0))
            has_ipv6 = True
        except Exception:
            pass

    if sock:
        sock.close()
    return has_ipv6

def _has_ipv6(host):
    """ Returns True if the system can bind an IPv6 address. """
    sock = None
    has_ipv6 = False

    if socket.has_ipv6:
        # has_ipv6 returns true if cPython was compiled with IPv6 support.
        # It does not tell us if the system has IPv6 support enabled. To
        # determine that we must bind to an IPv6 address.
        # https://github.com/shazow/urllib3/pull/611
        # https://bugs.python.org/issue658327
        try:
            sock = socket.socket(socket.AF_INET6)
            sock.bind((host, 0))
            has_ipv6 = True
        except Exception:
            pass

    if sock:
        sock.close()
    return has_ipv6

def _has_ipv6(host):
    """ Returns True if the system can bind an IPv6 address. """
    sock = None
    has_ipv6 = False

    if socket.has_ipv6:
        # has_ipv6 returns true if cPython was compiled with IPv6 support.
        # It does not tell us if the system has IPv6 support enabled. To
        # determine that we must bind to an IPv6 address.
        # https://github.com/shazow/urllib3/pull/611
        # https://bugs.python.org/issue658327
        try:
            sock = socket.socket(socket.AF_INET6)
            sock.bind((host, 0))
            has_ipv6 = True
        except Exception:
            pass

    if sock:
        sock.close()
    return has_ipv6

def _has_ipv6(host):
    """ Returns True if the system can bind an IPv6 address. """
    sock = None
    has_ipv6 = False

    if socket.has_ipv6:
        # has_ipv6 returns true if cPython was compiled with IPv6 support.
        # It does not tell us if the system has IPv6 support enabled. To
        # determine that we must bind to an IPv6 address.
        # https://github.com/shazow/urllib3/pull/611
        # https://bugs.python.org/issue658327
        try:
            sock = socket.socket(socket.AF_INET6)
            sock.bind((host, 0))
            has_ipv6 = True
        except Exception:
            pass

    if sock:
        sock.close()
    return has_ipv6

def _has_ipv6(host):
    """ Returns True if the system can bind an IPv6 address. """
    sock = None
    has_ipv6 = False

    if socket.has_ipv6:
        # has_ipv6 returns true if cPython was compiled with IPv6 support.
        # It does not tell us if the system has IPv6 support enabled. To
        # determine that we must bind to an IPv6 address.
        # https://github.com/shazow/urllib3/pull/611
        # https://bugs.python.org/issue658327
        try:
            sock = socket.socket(socket.AF_INET6)
            sock.bind((host, 0))
            has_ipv6 = True
        except Exception:
            pass

    if sock:
        sock.close()
    return has_ipv6

def test_main():
    tests = [TestFTPClass, TestTimeouts]
    if socket.has_ipv6:
        try:
            DummyFTPServer((HOST, 0), af=socket.AF_INET6)
        except socket.error:
            pass
        else:
            tests.append(TestIPv6Environment)

    if ssl is not None:
        tests.extend([TestTLS_FTPClassMixin, TestTLS_FTPClass])

    thread_info = support.threading_setup()
    try:
        support.run_unittest(*tests)
    finally:
        support.threading_cleanup(*thread_info)

def _has_ipv6(host):
    """ Returns True if the system can bind an IPv6 address. """
    sock = None
    has_ipv6 = False

    if socket.has_ipv6:
        # has_ipv6 returns true if cPython was compiled with IPv6 support.
        # It does not tell us if the system has IPv6 support enabled. To
        # determine that we must bind to an IPv6 address.
        # https://github.com/shazow/urllib3/pull/611
        # https://bugs.python.org/issue658327
        try:
            sock = socket.socket(socket.AF_INET6)
            sock.bind((host, 0))
            has_ipv6 = True
        except Exception:
            pass

    if sock:
        sock.close()
    return has_ipv6

def _has_ipv6(host):
    """ Returns True if the system can bind an IPv6 address. """
    sock = None
    has_ipv6 = False

    if socket.has_ipv6:
        # has_ipv6 returns true if cPython was compiled with IPv6 support.
        # It does not tell us if the system has IPv6 support enabled. To
        # determine that we must bind to an IPv6 address.
        # https://github.com/shazow/urllib3/pull/611
        # https://bugs.python.org/issue658327
        try:
            sock = socket.socket(socket.AF_INET6)
            sock.bind((host, 0))
            has_ipv6 = True
        except Exception:
            pass

    if sock:
        sock.close()
    return has_ipv6