connection

def allowed_gai_family():
    """This function is designed to work in the context of
    getaddrinfo, where family=socket.AF_UNSPEC is the default and
    will perform a DNS search for both IPv6 and IPv4 records."""

    family = socket.AF_INET
    if HAS_IPV6:
        family = socket.AF_UNSPEC
    return family

def create_connection(
    address,
    timeout=socket._GLOBAL_DEFAULT_TIMEOUT,
    source_address=None,
    socket_options=None,
):
    """Connect to *address* and return the socket object.

    Convenience function.  Connect to *address* (a 2-tuple ``(host,
    port)``) and return the socket object.  Passing the optional
    *timeout* parameter will set the timeout on the socket instance
    before attempting to connect.  If no *timeout* is supplied, the
    global default timeout setting returned by :func:`socket.getdefaulttimeout`
    is used.  If *source_address* is set it must be a tuple of (host, port)
    for the socket to bind as a source address before making the connection.
    An host of '' or port 0 tells the OS to use the default.
    """

    host, port = address
    if host.startswith("["):
        host = host.strip("[]")
    err = None

    # Using the value from allowed_gai_family() in the context of getaddrinfo lets
    # us select whether to work with IPv4 DNS records, IPv6 records, or both.
    # The original create_connection function always returns all records.
    family = allowed_gai_family()

    try:
        host.encode("idna")
    except UnicodeError:
        return six.raise_from(
            LocationParseError(u"'%s', label empty or too long" % host), None
        )

    for res in socket.getaddrinfo(host, port, family, socket.SOCK_STREAM):
        af, socktype, proto, canonname, sa = res
        sock = None
        try:
            sock = socket.socket(af, socktype, proto)

            # If provided, set socket level options before connecting.
            _set_socket_options(sock, socket_options)

            if timeout is not socket._GLOBAL_DEFAULT_TIMEOUT:
                sock.settimeout(timeout)
            if source_address:
                sock.bind(source_address)
            sock.connect(sa)
            return sock

        except socket.error as e:
            err = e
            if sock is not None:
                sock.close()
                sock = None

    if err is not None:
        raise err

    raise socket.error("getaddrinfo returns an empty list")

def is_connection_dropped(conn):  # Platform-specific
    """
    Returns True if the connection is dropped and should be closed.

    :param conn:
        :class:`http.client.HTTPConnection` object.

    Note: For platforms like AppEngine, this will always return ``False`` to
    let the platform handle connection recycling transparently for us.
    """
    sock = getattr(conn, "sock", False)
    if sock is False:  # Platform-specific: AppEngine
        return False
    if sock is None:  # Connection already closed (such as by httplib).
        return True
    try:
        # Returns True if readable, which here means it's been dropped
        return wait_for_read(sock, timeout=0.0)
    except NoWayToWaitForSocketError:  # Platform-specific: AppEngine
        return False