Change behavior of ssl.match_hostname() to follow RFC 6125 (rhbz#1023742)
This commit is contained in:
Matej Stuchlik
parent
3dbbc14e76
commit
54afb027bd
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@ -0,0 +1,188 @@
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--- a/Doc/library/ssl.rst
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+++ b/Doc/library/ssl.rst
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@@ -283,10 +283,10 @@ Certificate handling
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Verify that *cert* (in decoded format as returned by
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:meth:`SSLSocket.getpeercert`) matches the given *hostname*. The rules
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applied are those for checking the identity of HTTPS servers as outlined
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- in :rfc:`2818`, except that IP addresses are not currently supported.
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- In addition to HTTPS, this function should be suitable for checking the
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- identity of servers in various SSL-based protocols such as FTPS, IMAPS,
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- POPS and others.
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+ in :rfc:`2818` and :rfc:`6125`, except that IP addresses are not currently
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+ supported. In addition to HTTPS, this function should be suitable for
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+ checking the identity of servers in various SSL-based protocols such as
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+ FTPS, IMAPS, POPS and others.
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:exc:`CertificateError` is raised on failure. On success, the function
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returns nothing::
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@@ -301,6 +301,13 @@ Certificate handling
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.. versionadded:: 3.2
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+ .. versionchanged:: 3.3.3
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+ The function now follows :rfc:`6125`, section 6.4.3 and does neither
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+ match multiple wildcards (e.g. ``*.*.com`` or ``*a*.example.org``) nor
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+ a wildcard inside an internationalized domain names (IDN) fragment.
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+ IDN A-labels such as ``www*.xn--pthon-kva.org`` are still supported,
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+ but ``x*.python.org`` no longer matches ``xn--tda.python.org``.
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+
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.. function:: cert_time_to_seconds(timestring)
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Returns a floating-point value containing a normal seconds-after-the-epoch
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unchanged:
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--- a/Lib/ssl.py
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+++ b/Lib/ssl.py
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@@ -129,25 +129,53 @@ class CertificateError(ValueError):
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pass
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-def _dnsname_to_pat(dn, max_wildcards=1):
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+def _dnsname_match(dn, hostname, max_wildcards=1):
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+ """Matching according to RFC 6125, section 6.4.3
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+
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+ http://tools.ietf.org/html/rfc6125#section-6.4.3
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+ """
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pats = []
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- for frag in dn.split(r'.'):
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- if frag.count('*') > max_wildcards:
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- # Issue #17980: avoid denials of service by refusing more
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- # than one wildcard per fragment. A survery of established
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- # policy among SSL implementations showed it to be a
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- # reasonable choice.
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- raise CertificateError(
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- "too many wildcards in certificate DNS name: " + repr(dn))
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- if frag == '*':
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- # When '*' is a fragment by itself, it matches a non-empty dotless
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- # fragment.
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- pats.append('[^.]+')
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- else:
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- # Otherwise, '*' matches any dotless fragment.
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- frag = re.escape(frag)
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- pats.append(frag.replace(r'\*', '[^.]*'))
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- return re.compile(r'\A' + r'\.'.join(pats) + r'\Z', re.IGNORECASE)
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+ if not dn:
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+ return False
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+
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+ leftmost, *remainder = dn.split(r'.')
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+
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+ wildcards = leftmost.count('*')
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+ if wildcards > max_wildcards:
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+ # Issue #17980: avoid denials of service by refusing more
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+ # than one wildcard per fragment. A survery of established
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+ # policy among SSL implementations showed it to be a
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+ # reasonable choice.
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+ raise CertificateError(
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+ "too many wildcards in certificate DNS name: " + repr(dn))
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+
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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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+
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+ # RFC 6125, section 6.4.3, subitem 1.
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+ # The client SHOULD NOT attempt to match a presented identifier in which
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+ # the wildcard character comprises a label other than the left-most label.
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+ if leftmost == '*':
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+ # When '*' is a fragment by itself, it matches a non-empty dotless
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+ # fragment.
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+ pats.append('[^.]+')
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+ elif leftmost.startswith('xn--') or hostname.startswith('xn--'):
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+ # RFC 6125, section 6.4.3, subitem 3.
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+ # The client SHOULD NOT attempt to match a presented identifier
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+ # where the wildcard character is embedded within an A-label or
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+ # U-label of an internationalized domain name.
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+ pats.append(re.escape(leftmost))
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+ else:
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+ # Otherwise, '*' matches any dotless string, e.g. www*
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+ pats.append(re.escape(leftmost).replace(r'\*', '[^.]*'))
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+
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+ # add the remaining fragments, ignore any wildcards
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+ for frag in remainder:
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+ pats.append(re.escape(frag))
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+
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+ pat = re.compile(r'\A' + r'\.'.join(pats) + r'\Z', re.IGNORECASE)
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+ return pat.match(hostname)
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def match_hostname(cert, hostname):
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unchanged:
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--- a/Lib/test/test_ssl.py
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+++ b/Lib/test/test_ssl.py
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@@ -304,11 +304,7 @@ class BasicSocketTests(unittest.TestCase
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fail(cert, 'Xa.com')
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fail(cert, '.a.com')
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- cert = {'subject': ((('commonName', 'a.*.com'),),)}
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- ok(cert, 'a.foo.com')
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- fail(cert, 'a..com')
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- fail(cert, 'a.com')
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-
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+ # only match one left-most wildcard
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cert = {'subject': ((('commonName', 'f*.com'),),)}
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ok(cert, 'foo.com')
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ok(cert, 'f.com')
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@@ -323,6 +319,36 @@ class BasicSocketTests(unittest.TestCase
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fail(cert, 'example.org')
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fail(cert, 'null.python.org')
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+ # error cases with wildcards
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+ cert = {'subject': ((('commonName', '*.*.a.com'),),)}
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+ fail(cert, 'bar.foo.a.com')
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+ fail(cert, 'a.com')
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+ fail(cert, 'Xa.com')
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+ fail(cert, '.a.com')
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+
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+ cert = {'subject': ((('commonName', 'a.*.com'),),)}
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+ fail(cert, 'a.foo.com')
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+ fail(cert, 'a..com')
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+ fail(cert, 'a.com')
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+
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+ # wildcard doesn't match IDNA prefix 'xn--'
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+ idna = 'püthon.python.org'.encode("idna").decode("ascii")
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+ cert = {'subject': ((('commonName', idna),),)}
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+ ok(cert, idna)
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+ cert = {'subject': ((('commonName', 'x*.python.org'),),)}
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+ fail(cert, idna)
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+ cert = {'subject': ((('commonName', 'xn--p*.python.org'),),)}
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+ fail(cert, idna)
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+
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+ # wildcard in first fragment and IDNA A-labels in sequent fragments
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+ # are supported.
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+ idna = 'www*.pythön.org'.encode("idna").decode("ascii")
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+ cert = {'subject': ((('commonName', idna),),)}
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+ ok(cert, 'www.pythön.org'.encode("idna").decode("ascii"))
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+ ok(cert, 'www1.pythön.org'.encode("idna").decode("ascii"))
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+ fail(cert, 'ftp.pythön.org'.encode("idna").decode("ascii"))
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+ fail(cert, 'pythön.org'.encode("idna").decode("ascii"))
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+
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# Slightly fake real-world example
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cert = {'notAfter': 'Jun 26 21:41:46 2011 GMT',
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'subject': ((('commonName', 'linuxfrz.org'),),),
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@@ -383,7 +409,7 @@ class BasicSocketTests(unittest.TestCase
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cert = {'subject': ((('commonName', 'a*b.com'),),)}
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ok(cert, 'axxb.com')
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cert = {'subject': ((('commonName', 'a*b.co*'),),)}
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- ok(cert, 'axxb.com')
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+ fail(cert, 'axxb.com')
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cert = {'subject': ((('commonName', 'a*b*.com'),),)}
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with self.assertRaises(ssl.CertificateError) as cm:
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ssl.match_hostname(cert, 'axxbxxc.com')
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--- a/Lib/ssl.py
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+++ b/Lib/ssl.py
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@@ -192,7 +192,7 @@ def match_hostname(cert, hostname):
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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 _dnsname_to_pat(value).match(hostname):
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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 not dnsnames:
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@@ -203,7 +203,7 @@ def match_hostname(cert, hostname):
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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_to_pat(value).match(hostname):
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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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11
python3.spec
11
python3.spec
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@ -126,7 +126,7 @@
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Summary: Version 3 of the Python programming language aka Python 3000
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Name: python3
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Version: %{pybasever}.2
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Release: 7%{?dist}
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Release: 8%{?dist}
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License: Python
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Group: Development/Languages
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@ -623,6 +623,11 @@ Patch185: 00185-CVE-2013-4238-hostname-check-bypass-in-SSL-module.patch
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# continuing bytecompilation for other files.
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Patch186: 00186-dont-raise-from-py_compile.patch
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# 00187 #
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# Fix for rhbz#1023742
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# Change behavior of ssl.match_hostname() to follow RFC 6125
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# See http://bugs.python.org/issue17997#msg194950 for more.
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Patch187: 00187-change-match_hostname-to-follow-RFC-6125.patch
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# (New patches go here ^^^)
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#
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@ -884,6 +889,7 @@ done
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%patch184 -p1
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%patch185 -p1
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%patch186 -p1
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%patch187 -p1
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# Currently (2010-01-15), http://docs.python.org/library is for 2.6, and there
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# are many differences between 2.6 and the Python 3 library.
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@ -1732,6 +1738,9 @@ rm -fr %{buildroot}
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# ======================================================
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%changelog
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* Tue Nov 05 2013 Matej Stuchlik <mstuchli@redhat.com> - 3.3.2-8
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- Changed behavior of ssl.match_hostname() to follow RFC 6125 (rhbz#1023742)
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* Wed Oct 30 2013 Bohuslav Kabrda <bkabrda@redhat.com> - 3.3.2-7
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- Bytecompile all *.py files properly during build (rhbz#1023607)
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