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import ctypes
import socket
import gnutls.connection
import gnutls.crypto
import gnutls.library
def get_https_cert_from_domain(domain):
"""
@param domain: a domain name to get a certificate from.
"""
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
cred = gnutls.connection.X509Credentials()
session = gnutls.connection.ClientSession(sock, cred)
session.connect((domain, 443))
session.handshake()
cert = session.peer_certificate
return cert
def get_cert_from_file(filepath):
with open(filepath) as f:
cert = gnutls.crypto.X509Certificate(f.read())
return cert
def get_cert_fingerprint(domain=None, filepath=None,
hash_type="SHA256", sep=":"):
"""
@param domain: a domain name to get a fingerprint from
@type domain: str
@param filepath: path to a file containing a PEM file
@type filepath: str
@param hash_type: the hash function to be used in the fingerprint.
must be one of SHA1, SHA224, SHA256, SHA384, SHA512
@type hash_type: str
@rparam: hex_fpr, a hexadecimal representation of a bytestring
containing the fingerprint.
@rtype: string
"""
if domain:
cert = get_https_cert_from_domain(domain)
if filepath:
cert = get_cert_from_file(filepath)
_buffer = ctypes.create_string_buffer(64)
buffer_length = ctypes.c_size_t(64)
SUPPORTED_DIGEST_FUN = ("SHA1", "SHA224", "SHA256", "SHA384", "SHA512")
if hash_type in SUPPORTED_DIGEST_FUN:
digestfunction = getattr(
gnutls.library.constants,
"GNUTLS_DIG_%s" % hash_type)
else:
# XXX improperlyconfigured or something
raise Exception("digest function not supported")
gnutls.library.functions.gnutls_x509_crt_get_fingerprint(
cert._c_object, digestfunction,
ctypes.byref(_buffer), ctypes.byref(buffer_length))
# deinit
#server_cert._X509Certificate__deinit(server_cert._c_object)
# needed? is segfaulting
fpr = ctypes.string_at(_buffer, buffer_length.value)
hex_fpr = sep.join(u"%02X" % ord(char) for char in fpr)
return hex_fpr
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