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204 lines
7.2 KiB
204 lines
7.2 KiB
"""The match_hostname() function from Python 3.7.0, essential when using SSL."""
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import sys
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import socket as _socket
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try:
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# Divergence: Python-3.7+'s _ssl has this exception type but older Pythons do not
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from _ssl import SSLCertVerificationError
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CertificateError = SSLCertVerificationError
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except:
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class CertificateError(ValueError):
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pass
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__version__ = '3.7.0.1'
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# Divergence: Added to deal with ipaddess as bytes on python2
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def _to_text(obj):
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if isinstance(obj, str) and sys.version_info < (3,):
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obj = unicode(obj, encoding='ascii', errors='strict')
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elif sys.version_info >= (3,) and isinstance(obj, bytes):
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obj = str(obj, encoding='ascii', errors='strict')
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return obj
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def _to_bytes(obj):
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if isinstance(obj, str) and sys.version_info >= (3,):
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obj = bytes(obj, encoding='ascii', errors='strict')
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elif sys.version_info < (3,) and isinstance(obj, unicode):
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obj = obj.encode('ascii', 'strict')
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return obj
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def _dnsname_match(dn, hostname):
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"""Matching according to RFC 6125, section 6.4.3
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- Hostnames are compared lower case.
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- For IDNA, both dn and hostname must be encoded as IDN A-label (ACE).
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- Partial wildcards like 'www*.example.org', multiple wildcards, sole
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wildcard or wildcards in labels other then the left-most label are not
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supported and a CertificateError is raised.
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- A wildcard must match at least one character.
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"""
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if not dn:
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return False
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wildcards = dn.count('*')
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# speed up common case w/o wildcards
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if not wildcards:
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return dn.lower() == hostname.lower()
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if wildcards > 1:
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# Divergence .format() to percent formatting for Python < 2.6
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raise CertificateError(
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"too many wildcards in certificate DNS name: %s" % repr(dn))
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dn_leftmost, sep, dn_remainder = dn.partition('.')
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if '*' in dn_remainder:
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# Only match wildcard in leftmost segment.
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# Divergence .format() to percent formatting for Python < 2.6
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raise CertificateError(
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"wildcard can only be present in the leftmost label: "
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"%s." % repr(dn))
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if not sep:
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# no right side
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# Divergence .format() to percent formatting for Python < 2.6
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raise CertificateError(
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"sole wildcard without additional labels are not support: "
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"%s." % repr(dn))
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if dn_leftmost != '*':
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# no partial wildcard matching
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# Divergence .format() to percent formatting for Python < 2.6
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raise CertificateError(
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"partial wildcards in leftmost label are not supported: "
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"%s." % repr(dn))
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hostname_leftmost, sep, hostname_remainder = hostname.partition('.')
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if not hostname_leftmost or not sep:
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# wildcard must match at least one char
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return False
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return dn_remainder.lower() == hostname_remainder.lower()
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def _inet_paton(ipname):
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"""Try to convert an IP address to packed binary form
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Supports IPv4 addresses on all platforms and IPv6 on platforms with IPv6
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support.
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"""
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# inet_aton() also accepts strings like '1'
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# Divergence: We make sure we have native string type for all python versions
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try:
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b_ipname = _to_bytes(ipname)
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except UnicodeError:
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raise ValueError("%s must be an all-ascii string." % repr(ipname))
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# Set ipname in native string format
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if sys.version_info < (3,):
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n_ipname = b_ipname
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else:
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n_ipname = ipname
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if n_ipname.count('.') == 3:
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try:
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return _socket.inet_aton(n_ipname)
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# Divergence: OSError on late python3. socket.error earlier.
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# Null bytes generate ValueError on python3(we want to raise
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# ValueError anyway), TypeError # earlier
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except (OSError, _socket.error, TypeError):
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pass
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try:
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return _socket.inet_pton(_socket.AF_INET6, n_ipname)
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# Divergence: OSError on late python3. socket.error earlier.
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# Null bytes generate ValueError on python3(we want to raise
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# ValueError anyway), TypeError # earlier
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except (OSError, _socket.error, TypeError):
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# Divergence .format() to percent formatting for Python < 2.6
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raise ValueError("%s is neither an IPv4 nor an IP6 "
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"address." % repr(ipname))
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except AttributeError:
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# AF_INET6 not available
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pass
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# Divergence .format() to percent formatting for Python < 2.6
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raise ValueError("%s is not an IPv4 address." % repr(ipname))
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def _ipaddress_match(ipname, host_ip):
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"""Exact matching of IP addresses.
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RFC 6125 explicitly doesn't define an algorithm for this
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(section 1.7.2 - "Out of Scope").
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"""
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# OpenSSL may add a trailing newline to a subjectAltName's IP address
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ip = _inet_paton(ipname.rstrip())
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return ip == host_ip
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def match_hostname(cert, hostname):
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"""Verify that *cert* (in decoded format as returned by
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SSLSocket.getpeercert()) matches the *hostname*. RFC 2818 and RFC 6125
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rules are followed.
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The function matches IP addresses rather than dNSNames if hostname is a
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valid ipaddress string. IPv4 addresses are supported on all platforms.
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IPv6 addresses are supported on platforms with IPv6 support (AF_INET6
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and inet_pton).
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CertificateError is raised on failure. On success, the function
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returns nothing.
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"""
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if not cert:
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raise ValueError("empty or no certificate, match_hostname needs a "
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"SSL socket or SSL context with either "
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"CERT_OPTIONAL or CERT_REQUIRED")
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try:
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# Divergence: Deal with hostname as bytes
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host_ip = _inet_paton(_to_text(hostname))
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except ValueError:
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# Not an IP address (common case)
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host_ip = None
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except UnicodeError:
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# Divergence: Deal with hostname as byte strings.
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# IP addresses should be all ascii, so we consider it not
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# an IP address if this fails
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host_ip = None
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dnsnames = []
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san = cert.get('subjectAltName', ())
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for key, value in san:
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if key == 'DNS':
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if host_ip is None and _dnsname_match(value, hostname):
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return
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dnsnames.append(value)
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elif key == 'IP Address':
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if host_ip is not None and _ipaddress_match(value, host_ip):
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return
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dnsnames.append(value)
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if not dnsnames:
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# The subject is only checked when there is no dNSName entry
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# in subjectAltName
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for sub in cert.get('subject', ()):
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for key, value in sub:
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# XXX according to RFC 2818, the most specific Common Name
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# must be used.
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if key == 'commonName':
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if _dnsname_match(value, hostname):
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return
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dnsnames.append(value)
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if len(dnsnames) > 1:
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raise CertificateError("hostname %r "
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"doesn't match either of %s"
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% (hostname, ', '.join(map(repr, dnsnames))))
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elif len(dnsnames) == 1:
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raise CertificateError("hostname %r "
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"doesn't match %r"
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% (hostname, dnsnames[0]))
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else:
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raise CertificateError("no appropriate commonName or "
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"subjectAltName fields were found")
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