1 files changed, 133 insertions, 0 deletions
diff --git a/urllib3/util/ssl_.py b/urllib3/util/ssl_.py
new file mode 100644
index 0000000..dee4b87
--- /dev/null
+++ b/urllib3/util/ssl_.py
@@ -0,0 +1,133 @@
+from binascii import hexlify, unhexlify
+from hashlib import md5, sha1
+
+from ..exceptions import SSLError
+
+
+try:  # Test for SSL features
+    SSLContext = None
+    HAS_SNI = False
+
+    import ssl
+    from ssl import wrap_socket, CERT_NONE, PROTOCOL_SSLv23
+    from ssl import SSLContext  # Modern SSL?
+    from ssl import HAS_SNI  # Has SNI?
+except ImportError:
+    pass
+
+
+def assert_fingerprint(cert, fingerprint):
+    """
+    Checks if given fingerprint matches the supplied certificate.
+
+    :param cert:
+        Certificate as bytes object.
+    :param fingerprint:
+        Fingerprint as string of hexdigits, can be interspersed by colons.
+    """
+
+    # Maps the length of a digest to a possible hash function producing
+    # this digest.
+    hashfunc_map = {
+        16: md5,
+        20: sha1
+    }
+
+    fingerprint = fingerprint.replace(':', '').lower()
+
+    digest_length, rest = divmod(len(fingerprint), 2)
+
+    if rest or digest_length not in hashfunc_map:
+        raise SSLError('Fingerprint is of invalid length.')
+
+    # We need encode() here for py32; works on py2 and p33.
+    fingerprint_bytes = unhexlify(fingerprint.encode())
+
+    hashfunc = hashfunc_map[digest_length]
+
+    cert_digest = hashfunc(cert).digest()
+
+    if not cert_digest == fingerprint_bytes:
+        raise SSLError('Fingerprints did not match. Expected "{0}", got "{1}".'
+                       .format(hexlify(fingerprint_bytes),
+                               hexlify(cert_digest)))
+
+
+def resolve_cert_reqs(candidate):
+    """
+    Resolves the argument to a numeric constant, which can be passed to
+    the wrap_socket function/method from the ssl module.
+    Defaults to :data:`ssl.CERT_NONE`.
+    If given a string it is assumed to be the name of the constant in the
+    :mod:`ssl` module or its abbrevation.
+    (So you can specify `REQUIRED` instead of `CERT_REQUIRED`.
+    If it's neither `None` nor a string we assume it is already the numeric
+    constant which can directly be passed to wrap_socket.
+    """
+    if candidate is None:
+        return CERT_NONE
+
+    if isinstance(candidate, str):
+        res = getattr(ssl, candidate, None)
+        if res is None:
+            res = getattr(ssl, 'CERT_' + candidate)
+        return res
+
+    return candidate
+
+
+def resolve_ssl_version(candidate):
+    """
+    like resolve_cert_reqs
+    """
+    if candidate is None:
+        return PROTOCOL_SSLv23
+
+    if isinstance(candidate, str):
+        res = getattr(ssl, candidate, None)
+        if res is None:
+            res = getattr(ssl, 'PROTOCOL_' + candidate)
+        return res
+
+    return candidate
+
+
+if SSLContext is not None:  # Python 3.2+
+    def ssl_wrap_socket(sock, keyfile=None, certfile=None, cert_reqs=None,
+                        ca_certs=None, server_hostname=None,
+                        ssl_version=None):
+        """
+        All arguments except `server_hostname` have the same meaning as for
+        :func:`ssl.wrap_socket`
+
+        :param server_hostname:
+            Hostname of the expected certificate
+        """
+        context = SSLContext(ssl_version)
+        context.verify_mode = cert_reqs
+
+        # Disable TLS compression to migitate CRIME attack (issue #309)
+        OP_NO_COMPRESSION = 0x20000
+        context.options |= OP_NO_COMPRESSION
+
+        if ca_certs:
+            try:
+                context.load_verify_locations(ca_certs)
+            # Py32 raises IOError
+            # Py33 raises FileNotFoundError
+            except Exception as e:  # Reraise as SSLError
+                raise SSLError(e)
+        if certfile:
+            # FIXME: This block needs a test.
+            context.load_cert_chain(certfile, keyfile)
+        if HAS_SNI:  # Platform-specific: OpenSSL with enabled SNI
+            return context.wrap_socket(sock, server_hostname=server_hostname)
+        return context.wrap_socket(sock)
+
+else:  # Python 3.1 and earlier
+    def ssl_wrap_socket(sock, keyfile=None, certfile=None, cert_reqs=None,
+                        ca_certs=None, server_hostname=None,
+                        ssl_version=None):
+        return wrap_socket(sock, keyfile=keyfile, certfile=certfile,
+                           ca_certs=ca_certs, cert_reqs=cert_reqs,
+                           ssl_version=ssl_version)