1 files changed, 71 insertions, 0 deletions
diff --git a/src/leap/crypto/certs.py b/src/leap/crypto/certs.py
new file mode 100644
index 00000000..8908865d
--- /dev/null
+++ b/src/leap/crypto/certs.py
@@ -0,0 +1,71 @@
+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