Adds optional support for SSL server certificate validation

boto/https_connection.py

+# Copyright 2007,2011 Google Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+# This file is derived from
+# http://code.google.com/p/googleappengine/source/browse/trunk/python/google/appengine/tools/https_wrapper.py?r=136

[Mike Schwartz, 2011/04/19 23:49:13]

I get a 404 when I try this URL

+
+
+"""Extensions to allow HTTPS requests with SSL certificate validation."""
+
+
+import httplib
+import re
+import socket
+import ssl
+
+import boto
+
+class InvalidCertificateException(httplib.HTTPException):

[Mike Schwartz, 2011/04/19 23:49:13]

Most of the rest of the boto code puts the exceptions in boto/boto/exception.py

I guess since it's inconsistently done, it's your call.

[xtof.g, 2011/04/20 16:18:38]

Well, this one is a subclass of a httplib exception, so I'm not sure it belongs
into boto/exception.py.

+  """Raised when a certificate is provided with an invalid hostname."""
+
+  def __init__(self, host, cert, reason):
+    """Constructor.
+
+    Args:
+      host: The hostname the connection was made to.
+      cert: The SSL certificate (as a dictionary) the host returned.
+    """
+    httplib.HTTPException.__init__(self)
+    self.host = host
+    self.cert = cert
+    self.reason = reason
+
+  def __str__(self):
+    return ('Host %s returned an invalid certificate (%s): %s' %
+            (self.host, self.reason, self.cert))
+
+def GetValidHostsForCert(cert):
+  """Returns a list of valid host globs for an SSL certificate.
+
+  Args:
+    cert: A dictionary representing an SSL certificate.
+  Returns:
+    list: A list of valid host globs.
+  """
+  if 'subjectAltName' in cert:
+    return [x[1] for x in cert['subjectAltName'] if x[0].lower() == 'dns']
+  else:
+    return [x[0][1] for x in cert['subject']
+            if x[0][0].lower() == 'commonname']
+
+def ValidateCertificateHostname(cert, hostname):
+  """Validates that a given hostname is valid for an SSL certificate.
+
+  Args:
+    cert: A dictionary representing an SSL certificate.
+    hostname: The hostname to test.
+  Returns:
+    bool: Whether or not the hostname is valid for this certificate.
+  """
+  hosts = GetValidHostsForCert(cert)
+  boto.log.debug(
+      "validating server certificate: hostname=%s, certificate hosts=%s",
+      hostname, hosts)
+  for host in hosts:
+    host_re = host.replace('.', '\.').replace('*', '[^.]*')
+    if re.search('^%s$' % (host_re,), hostname, re.I):
+      return True
+  return False
+
+
+class CertValidatingHTTPSConnection(httplib.HTTPConnection):
+  """An HTTPConnection that connects over SSL and validates certificates."""
+
+  default_port = httplib.HTTPS_PORT
+
+  def __init__(self, host, port=None, key_file=None, cert_file=None,
+               ca_certs=None, strict=None, **kwargs):
+    """Constructor.
+
+    Args:
+      host: The hostname. Can be in 'host:port' form.
+      port: The port. Defaults to 443.
+      key_file: A file containing the client's private key
+      cert_file: A file containing the client's certificates
+      ca_certs: A file contianing a set of concatenated certificate authority
+          certs for validating the server against.
+      strict: When true, causes BadStatusLine to be raised if the status line
+          can't be parsed as a valid HTTP/1.0 or 1.1 status line.
+    """
+    httplib.HTTPConnection.__init__(self, host, port, strict, **kwargs)
+    self.key_file = key_file
+    self.cert_file = cert_file
+    self.ca_certs = ca_certs
+
+  def connect(self):
+    "Connect to a host on a given (SSL) port."
+    sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+    sock.connect((self.host, self.port))
+    boto.log.debug("wrapping ssl socket; CA certificate file=%s",·
+                   self.ca_certs)
+    self.sock = ssl.wrap_socket(sock, keyfile=self.key_file,
+                                certfile=self.cert_file,
+                                cert_reqs=ssl.CERT_REQUIRED,
+                                ca_certs=self.ca_certs)
+    cert = self.sock.getpeercert()
+    hostname = self.host.split(':', 0)[0]
+    if not ValidateCertificateHostname(cert, hostname):
+      raise InvalidCertificateException(hostname, cert, 'hostname mismatch')
+
+