# Copyright (c) 2016 Hewlett Packard Enterprise Development LP
#
# Redistribution and use of this software in source and binary forms,
# with or without modification, are permitted provided that the following
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import hashlib
import socket
import ssl

import six


def get_cert_fingerprint(url, log=None):
    """
    Get the SHA-1 certificate fingerprint of a TLS server on the network.
    """
    parsed = six.moves.urllib.parse.urlparse(url)
    host, _, port = parsed.netloc.partition(':')
    if port:
        port = int(port)
    else:
        port = socket.getservbyname(parsed.scheme)
    if log:
        log.info('retrieving certificate from server %s, port %i', host, port)
    cert = ssl.get_server_certificate((host, port),
                                      ssl_version=ssl.PROTOCOL_TLSv1)
    fprint = hashlib.sha1(ssl.PEM_cert_to_DER_cert(cert)).hexdigest()
    if log:
        log.info('found thumbprint %s', fprint)
    return fprint