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- import os
- import socket
- import atexit
- import re
- import functools
- import urllib.request
- import http.client
- from pkg_resources import ResolutionError, ExtractionError
- try:
- import ssl
- except ImportError:
- ssl = None
- __all__ = [
- 'VerifyingHTTPSHandler', 'find_ca_bundle', 'is_available', 'cert_paths',
- 'opener_for'
- ]
- cert_paths = """
- /etc/pki/tls/certs/ca-bundle.crt
- /etc/ssl/certs/ca-certificates.crt
- /usr/share/ssl/certs/ca-bundle.crt
- /usr/local/share/certs/ca-root.crt
- /etc/ssl/cert.pem
- /System/Library/OpenSSL/certs/cert.pem
- /usr/local/share/certs/ca-root-nss.crt
- /etc/ssl/ca-bundle.pem
- """.strip().split()
- try:
- HTTPSHandler = urllib.request.HTTPSHandler
- HTTPSConnection = http.client.HTTPSConnection
- except AttributeError:
- HTTPSHandler = HTTPSConnection = object
- is_available = ssl is not None and object not in (
- HTTPSHandler, HTTPSConnection)
- try:
- from ssl import CertificateError, match_hostname
- except ImportError:
- try:
- from backports.ssl_match_hostname import CertificateError
- from backports.ssl_match_hostname import match_hostname
- except ImportError:
- CertificateError = None
- match_hostname = None
- if not CertificateError:
- class CertificateError(ValueError):
- pass
- if not match_hostname:
- def _dnsname_match(dn, hostname, max_wildcards=1):
- """Matching according to RFC 6125, section 6.4.3
- https://tools.ietf.org/html/rfc6125#section-6.4.3
- """
- pats = []
- if not dn:
- return False
- # Ported from python3-syntax:
- # leftmost, *remainder = dn.split(r'.')
- 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 survey 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 match_hostname(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")
- dnsnames = []
- san = cert.get('subjectAltName', ())
- for key, value in san:
- if key == 'DNS':
- if _dnsname_match(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 _dnsname_match(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 VerifyingHTTPSHandler(HTTPSHandler):
- """Simple verifying handler: no auth, subclasses, timeouts, etc."""
- def __init__(self, ca_bundle):
- self.ca_bundle = ca_bundle
- HTTPSHandler.__init__(self)
- def https_open(self, req):
- return self.do_open(
- lambda host, **kw: VerifyingHTTPSConn(host, self.ca_bundle, **kw),
- req
- )
- class VerifyingHTTPSConn(HTTPSConnection):
- """Simple verifying connection: no auth, subclasses, timeouts, etc."""
- def __init__(self, host, ca_bundle, **kw):
- HTTPSConnection.__init__(self, host, **kw)
- self.ca_bundle = ca_bundle
- def connect(self):
- sock = socket.create_connection(
- (self.host, self.port), getattr(self, 'source_address', None)
- )
- # Handle the socket if a (proxy) tunnel is present
- if hasattr(self, '_tunnel') and getattr(self, '_tunnel_host', None):
- self.sock = sock
- self._tunnel()
- # http://bugs.python.org/issue7776: Python>=3.4.1 and >=2.7.7
- # change self.host to mean the proxy server host when tunneling is
- # being used. Adapt, since we are interested in the destination
- # host for the match_hostname() comparison.
- actual_host = self._tunnel_host
- else:
- actual_host = self.host
- if hasattr(ssl, 'create_default_context'):
- ctx = ssl.create_default_context(cafile=self.ca_bundle)
- self.sock = ctx.wrap_socket(sock, server_hostname=actual_host)
- else:
- # This is for python < 2.7.9 and < 3.4?
- self.sock = ssl.wrap_socket(
- sock, cert_reqs=ssl.CERT_REQUIRED, ca_certs=self.ca_bundle
- )
- try:
- match_hostname(self.sock.getpeercert(), actual_host)
- except CertificateError:
- self.sock.shutdown(socket.SHUT_RDWR)
- self.sock.close()
- raise
- def opener_for(ca_bundle=None):
- """Get a urlopen() replacement that uses ca_bundle for verification"""
- return urllib.request.build_opener(
- VerifyingHTTPSHandler(ca_bundle or find_ca_bundle())
- ).open
- # from jaraco.functools
- def once(func):
- @functools.wraps(func)
- def wrapper(*args, **kwargs):
- if not hasattr(func, 'always_returns'):
- func.always_returns = func(*args, **kwargs)
- return func.always_returns
- return wrapper
- @once
- def get_win_certfile():
- try:
- import wincertstore
- except ImportError:
- return None
- class CertFile(wincertstore.CertFile):
- def __init__(self):
- super(CertFile, self).__init__()
- atexit.register(self.close)
- def close(self):
- try:
- super(CertFile, self).close()
- except OSError:
- pass
- _wincerts = CertFile()
- _wincerts.addstore('CA')
- _wincerts.addstore('ROOT')
- return _wincerts.name
- def find_ca_bundle():
- """Return an existing CA bundle path, or None"""
- extant_cert_paths = filter(os.path.isfile, cert_paths)
- return (
- get_win_certfile()
- or next(extant_cert_paths, None)
- or _certifi_where()
- )
- def _certifi_where():
- try:
- return __import__('certifi').where()
- except (ImportError, ResolutionError, ExtractionError):
- pass
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