socket.py 文件源码

def create_connection(address, timeout=_GLOBAL_DEFAULT_TIMEOUT, source_address=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:`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
    err = None
    for res in getaddrinfo(host, port, 0, SOCK_STREAM):
        af, socktype, proto, _canonname, sa = res
        sock = None
        try:
            sock = socket(af, socktype, proto)
            if timeout is not _GLOBAL_DEFAULT_TIMEOUT:
                sock.settimeout(timeout)
            if source_address:
                sock.bind(source_address)
            sock.connect(sa)
            return sock
        except error, ex:
            err = ex
            sys.exc_clear()
            if sock is not None:
                sock.close()
    if err is not None:
        raise err
    else:
        raise error("getaddrinfo returns an empty list")