[Findit] Initiate Findit for crash.

tools/findit/https.py

+# Copyright (c) 2014 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+"""
+Provides a utility function for https connections with certificate verification.
+
+The verification is based on http://tools.ietf.org/html/rfc6125#section-6.4.3
+and the code is from Lib/ssl.py in python3:
+  http://hg.python.org/cpython/file/4dac45f88d45/Lib/ssl.py
+
+One use case is to download Chromium DEPS file in a secure way:
+  https://src.chromium.org/chrome/trunk/src/DEPS
+
+Notice: python 2.7 or newer is required.
+"""
+
+import httplib
+import os
+import re
+import socket
+import ssl
+import urllib2
+
+
+_SCRIPT_DIR = os.path.dirname(__file__)
+_TRUSTED_ROOT_CERTS = os.path.join(_SCRIPT_DIR, 'cacert.pem')
+
+
+class CertificateError(ValueError):
+  pass
+
+
+def _DNSNameMatch(dn, hostname, max_wildcards=1):
+  """Matching according to RFC 6125, section 6.4.3
+
+  http://tools.ietf.org/html/rfc6125#section-6.4.3
+  """
+  pats = []
+  if not dn:
+    return False
+
+  parts = dn.split(r'.')
+  leftmost = parts[0]
+  remainder = parts[1:]
+
+  wildcards = leftmost.count('*')
+  if wildcards > max_wildcards:
+    # Issue #17980: avoid denials of service by refusing more
+    # than one wildcard per fragment.  A survery of established
+    # policy among SSL implementations showed it to be a
+    # reasonable choice.
+    raise CertificateError(
+        'too many wildcards in certificate DNS name: ' + repr(dn))
+
+  # speed up common case w/o wildcards
+  if not wildcards:
+    return dn.lower() == hostname.lower()
+
+  # RFC 6125, section 6.4.3, subitem 1.
+  # The client SHOULD NOT attempt to match a presented identifier in which
+  # the wildcard character comprises a label other than the left-most label.
+  if leftmost == '*':
+    # When '*' is a fragment by itself, it matches a non-empty dotless
+    # fragment.
+    pats.append('[^.]+')
+  elif leftmost.startswith('xn--') or hostname.startswith('xn--'):
+    # RFC 6125, section 6.4.3, subitem 3.
+    # The client SHOULD NOT attempt to match a presented identifier
+    # where the wildcard character is embedded within an A-label or
+    # U-label of an internationalized domain name.
+    pats.append(re.escape(leftmost))
+  else:
+    # Otherwise, '*' matches any dotless string, e.g. www*
+    pats.append(re.escape(leftmost).replace(r'\*', '[^.]*'))
+
+  # add the remaining fragments, ignore any wildcards
+  for frag in remainder:
+    pats.append(re.escape(frag))
+
+  pat = re.compile(r'\A' + r'\.'.join(pats) + r'\Z', re.IGNORECASE)
+  return pat.match(hostname)
+
+
+def _MatchHostname(cert, hostname):
+  """Verify that *cert* (in decoded format as returned by
+  SSLSocket.getpeercert()) matches the *hostname*.  RFC 2818 and RFC 6125
+  rules are followed, but IP addresses are not accepted for *hostname*.
+
+  CertificateError is raised on failure. On success, the function
+  returns nothing.
+  """
+  if not cert:
+    raise ValueError('empty or no certificate, match_hostname needs a '
+                     'SSL socket or SSL context with either '
+                     'CERT_OPTIONAL or CERT_REQUIRED')
+  dnsnames = []
+  san = cert.get('subjectAltName', ())
+  for key, value in san:
+    if key == 'DNS':
+      if _DNSNameMatch(value, hostname):
+        return
+      dnsnames.append(value)
+  if not dnsnames:
+    # The subject is only checked when there is no dNSName entry
+    # in subjectAltName
+    for sub in cert.get('subject', ()):
+      for key, value in sub:
+        # XXX according to RFC 2818, the most specific Common Name
+        # must be used.
+        if key == 'commonName':
+          if _DNSNameMatch(value, hostname):
+            return
+          dnsnames.append(value)
+  if len(dnsnames) > 1:
+    raise CertificateError('hostname %r doesn\'t match either of %s'
+                           % (hostname, ', '.join(map(repr, dnsnames))))
+  elif len(dnsnames) == 1:
+    raise CertificateError('hostname %r doesn\'t match %r'
+                           % (hostname, dnsnames[0]))
+  else:
+    raise CertificateError('no appropriate commonName or '
+                           'subjectAltName fields were found')
+
+
+class HTTPSConnection(httplib.HTTPSConnection):
+
+  def __init__(self, host, root_certs=_TRUSTED_ROOT_CERTS, **kwargs):
+    self.root_certs = root_certs
+    httplib.HTTPSConnection.__init__(self, host, **kwargs)
+
+  def connect(self):
+    # Overrides for certificate verification.
+    args = [(self.host, self.port), self.timeout,]
+    if self.source_address:
+      args.append(self.source_address)
+    sock = socket.create_connection(*args)
+
+    if self._tunnel_host:
+      self.sock = sock
+      self._tunnel()
+
+    # Wrap the socket for verification with the root certs.
+    kwargs = {}
+    if self.root_certs is not None:
+      kwargs.update(cert_reqs=ssl.CERT_REQUIRED, ca_certs=self.root_certs)
+    self.sock = ssl.wrap_socket(sock, **kwargs)
+
+    # Check hostname.
+    try:
+      _MatchHostname(self.sock.getpeercert(), self.host)
+    except CertificateError:
+      self.sock.shutdown(socket.SHUT_RDWR)
+      self.sock.close()
+      raise
+
+
+class HTTPSHandler(urllib2.HTTPSHandler):
+
+  def __init__(self, root_certs=_TRUSTED_ROOT_CERTS):
+    urllib2.HTTPSHandler.__init__(self)
+    self.root_certs = root_certs
+
+  def https_open(self, req):
+    # Pass a reference to the function below so that verification against
+    # trusted root certs could be injected.
+    return self.do_open(self.GetConnection, req)
+
+  def GetConnection(self, host, **kwargs):
+    params = dict(root_certs=self.root_certs)
+    params.update(kwargs)
+    return HTTPSConnection(host, **params)
+
+
+def SendRequest(https_url):
+  """Send request to the given https url, and return the server response.
+
+  Args:
+    https_url: The https url to send request to.
+
+  Returns:
+    A string that is the response from the server.
+
+  Raises:
+    ValueError: Unexpected value is received during certificate verification.
+    CertificateError: Certificate verification fails.
+  """
+  if not https_url or not https_url.startswith('https://'):
+    raise ValueError('Not a https request for url %s.' % str(https_url))
+
+  url_opener = urllib2.build_opener(HTTPSHandler)
+  return url_opener.open(https_url).read()
+
+
+if __name__ == '__main__':
+  print SendRequest('https://src.chromium.org/chrome/trunk/src/DEPS')