ssl_support.py 8.3 KB

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  1. import os
  2. import socket
  3. import atexit
  4. import re
  5. import functools
  6. from setuptools.extern.six.moves import urllib, http_client, map, filter
  7. from pkg_resources import ResolutionError, ExtractionError
  8. try:
  9. import ssl
  10. except ImportError:
  11. ssl = None
  12. __all__ = [
  13. 'VerifyingHTTPSHandler', 'find_ca_bundle', 'is_available', 'cert_paths',
  14. 'opener_for'
  15. ]
  16. cert_paths = """
  17. /etc/pki/tls/certs/ca-bundle.crt
  18. /etc/ssl/certs/ca-certificates.crt
  19. /usr/share/ssl/certs/ca-bundle.crt
  20. /usr/local/share/certs/ca-root.crt
  21. /etc/ssl/cert.pem
  22. /System/Library/OpenSSL/certs/cert.pem
  23. /usr/local/share/certs/ca-root-nss.crt
  24. /etc/ssl/ca-bundle.pem
  25. """.strip().split()
  26. try:
  27. HTTPSHandler = urllib.request.HTTPSHandler
  28. HTTPSConnection = http_client.HTTPSConnection
  29. except AttributeError:
  30. HTTPSHandler = HTTPSConnection = object
  31. is_available = ssl is not None and object not in (HTTPSHandler, HTTPSConnection)
  32. try:
  33. from ssl import CertificateError, match_hostname
  34. except ImportError:
  35. try:
  36. from backports.ssl_match_hostname import CertificateError
  37. from backports.ssl_match_hostname import match_hostname
  38. except ImportError:
  39. CertificateError = None
  40. match_hostname = None
  41. if not CertificateError:
  42. class CertificateError(ValueError):
  43. pass
  44. if not match_hostname:
  45. def _dnsname_match(dn, hostname, max_wildcards=1):
  46. """Matching according to RFC 6125, section 6.4.3
  47. https://tools.ietf.org/html/rfc6125#section-6.4.3
  48. """
  49. pats = []
  50. if not dn:
  51. return False
  52. # Ported from python3-syntax:
  53. # leftmost, *remainder = dn.split(r'.')
  54. parts = dn.split(r'.')
  55. leftmost = parts[0]
  56. remainder = parts[1:]
  57. wildcards = leftmost.count('*')
  58. if wildcards > max_wildcards:
  59. # Issue #17980: avoid denials of service by refusing more
  60. # than one wildcard per fragment. A survey of established
  61. # policy among SSL implementations showed it to be a
  62. # reasonable choice.
  63. raise CertificateError(
  64. "too many wildcards in certificate DNS name: " + repr(dn))
  65. # speed up common case w/o wildcards
  66. if not wildcards:
  67. return dn.lower() == hostname.lower()
  68. # RFC 6125, section 6.4.3, subitem 1.
  69. # The client SHOULD NOT attempt to match a presented identifier in which
  70. # the wildcard character comprises a label other than the left-most label.
  71. if leftmost == '*':
  72. # When '*' is a fragment by itself, it matches a non-empty dotless
  73. # fragment.
  74. pats.append('[^.]+')
  75. elif leftmost.startswith('xn--') or hostname.startswith('xn--'):
  76. # RFC 6125, section 6.4.3, subitem 3.
  77. # The client SHOULD NOT attempt to match a presented identifier
  78. # where the wildcard character is embedded within an A-label or
  79. # U-label of an internationalized domain name.
  80. pats.append(re.escape(leftmost))
  81. else:
  82. # Otherwise, '*' matches any dotless string, e.g. www*
  83. pats.append(re.escape(leftmost).replace(r'\*', '[^.]*'))
  84. # add the remaining fragments, ignore any wildcards
  85. for frag in remainder:
  86. pats.append(re.escape(frag))
  87. pat = re.compile(r'\A' + r'\.'.join(pats) + r'\Z', re.IGNORECASE)
  88. return pat.match(hostname)
  89. def match_hostname(cert, hostname):
  90. """Verify that *cert* (in decoded format as returned by
  91. SSLSocket.getpeercert()) matches the *hostname*. RFC 2818 and RFC 6125
  92. rules are followed, but IP addresses are not accepted for *hostname*.
  93. CertificateError is raised on failure. On success, the function
  94. returns nothing.
  95. """
  96. if not cert:
  97. raise ValueError("empty or no certificate")
  98. dnsnames = []
  99. san = cert.get('subjectAltName', ())
  100. for key, value in san:
  101. if key == 'DNS':
  102. if _dnsname_match(value, hostname):
  103. return
  104. dnsnames.append(value)
  105. if not dnsnames:
  106. # The subject is only checked when there is no dNSName entry
  107. # in subjectAltName
  108. for sub in cert.get('subject', ()):
  109. for key, value in sub:
  110. # XXX according to RFC 2818, the most specific Common Name
  111. # must be used.
  112. if key == 'commonName':
  113. if _dnsname_match(value, hostname):
  114. return
  115. dnsnames.append(value)
  116. if len(dnsnames) > 1:
  117. raise CertificateError("hostname %r "
  118. "doesn't match either of %s"
  119. % (hostname, ', '.join(map(repr, dnsnames))))
  120. elif len(dnsnames) == 1:
  121. raise CertificateError("hostname %r "
  122. "doesn't match %r"
  123. % (hostname, dnsnames[0]))
  124. else:
  125. raise CertificateError("no appropriate commonName or "
  126. "subjectAltName fields were found")
  127. class VerifyingHTTPSHandler(HTTPSHandler):
  128. """Simple verifying handler: no auth, subclasses, timeouts, etc."""
  129. def __init__(self, ca_bundle):
  130. self.ca_bundle = ca_bundle
  131. HTTPSHandler.__init__(self)
  132. def https_open(self, req):
  133. return self.do_open(
  134. lambda host, **kw: VerifyingHTTPSConn(host, self.ca_bundle, **kw), req
  135. )
  136. class VerifyingHTTPSConn(HTTPSConnection):
  137. """Simple verifying connection: no auth, subclasses, timeouts, etc."""
  138. def __init__(self, host, ca_bundle, **kw):
  139. HTTPSConnection.__init__(self, host, **kw)
  140. self.ca_bundle = ca_bundle
  141. def connect(self):
  142. sock = socket.create_connection(
  143. (self.host, self.port), getattr(self, 'source_address', None)
  144. )
  145. # Handle the socket if a (proxy) tunnel is present
  146. if hasattr(self, '_tunnel') and getattr(self, '_tunnel_host', None):
  147. self.sock = sock
  148. self._tunnel()
  149. # http://bugs.python.org/issue7776: Python>=3.4.1 and >=2.7.7
  150. # change self.host to mean the proxy server host when tunneling is
  151. # being used. Adapt, since we are interested in the destination
  152. # host for the match_hostname() comparison.
  153. actual_host = self._tunnel_host
  154. else:
  155. actual_host = self.host
  156. if hasattr(ssl, 'create_default_context'):
  157. ctx = ssl.create_default_context(cafile=self.ca_bundle)
  158. self.sock = ctx.wrap_socket(sock, server_hostname=actual_host)
  159. else:
  160. # This is for python < 2.7.9 and < 3.4?
  161. self.sock = ssl.wrap_socket(
  162. sock, cert_reqs=ssl.CERT_REQUIRED, ca_certs=self.ca_bundle
  163. )
  164. try:
  165. match_hostname(self.sock.getpeercert(), actual_host)
  166. except CertificateError:
  167. self.sock.shutdown(socket.SHUT_RDWR)
  168. self.sock.close()
  169. raise
  170. def opener_for(ca_bundle=None):
  171. """Get a urlopen() replacement that uses ca_bundle for verification"""
  172. return urllib.request.build_opener(
  173. VerifyingHTTPSHandler(ca_bundle or find_ca_bundle())
  174. ).open
  175. # from jaraco.functools
  176. def once(func):
  177. @functools.wraps(func)
  178. def wrapper(*args, **kwargs):
  179. if not hasattr(func, 'always_returns'):
  180. func.always_returns = func(*args, **kwargs)
  181. return func.always_returns
  182. return wrapper
  183. @once
  184. def get_win_certfile():
  185. try:
  186. import wincertstore
  187. except ImportError:
  188. return None
  189. class CertFile(wincertstore.CertFile):
  190. def __init__(self):
  191. super(CertFile, self).__init__()
  192. atexit.register(self.close)
  193. def close(self):
  194. try:
  195. super(CertFile, self).close()
  196. except OSError:
  197. pass
  198. _wincerts = CertFile()
  199. _wincerts.addstore('CA')
  200. _wincerts.addstore('ROOT')
  201. return _wincerts.name
  202. def find_ca_bundle():
  203. """Return an existing CA bundle path, or None"""
  204. extant_cert_paths = filter(os.path.isfile, cert_paths)
  205. return (
  206. get_win_certfile()
  207. or next(extant_cert_paths, None)
  208. or _certifi_where()
  209. )
  210. def _certifi_where():
  211. try:
  212. return __import__('certifi').where()
  213. except (ImportError, ResolutionError, ExtractionError):
  214. pass