David
93 lines
3.0 KiB
Python
93 lines
3.0 KiB
Python
# This software is provided 'as-is', without any express or implied
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# warranty. In no event will the author be held liable for any damages
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# arising from the use of this software.
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#
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# Permission is granted to anyone to use this software for any purpose,
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# including commercial applications, and to alter it and redistribute it
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# freely, subject to the following restrictions:
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#
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# 1. The origin of this software must not be misrepresented; you must not
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# claim that you wrote the original software. If you use this software
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# in a product, an acknowledgment in the product documentation would be
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# appreciated but is not required.
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# 2. Altered source versions must be plainly marked as such, and must not be
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# misrepresented as being the original software.
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# 3. This notice may not be removed or altered from any source distribution.
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#
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# Copyright (c) 2008 Greg Hewgill http://hewgill.com
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#
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# This has been modified from the original software.
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# Copyright (c) 2011 William Grant <me@williamgrant.id.au>
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__all__ = [
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'get_txt'
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]
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def get_txt_dnspython(name, timeout=5):
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"""Return a TXT record associated with a DNS name."""
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try:
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a = dns.resolver.query(name, dns.rdatatype.TXT,raise_on_no_answer=False, lifetime=timeout)
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for r in a.response.answer:
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if r.rdtype == dns.rdatatype.TXT:
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return b"".join(list(r.items)[0].strings)
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except dns.resolver.NXDOMAIN: pass
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except dns.resolver.NoNameservers: pass
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return None
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def get_txt_pydns(name, timeout=5):
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"""Return a TXT record associated with a DNS name."""
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# Older pydns releases don't like a trailing dot.
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if name.endswith('.'):
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name = name[:-1]
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response = DNS.DnsRequest(name, qtype='txt', timeout=timeout).req()
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if not response.answers:
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return None
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for answer in response.answers:
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if answer['typename'].lower() == 'txt':
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return b''.join(answer['data'])
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return None
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# No longer used since it doesn't support timeout
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def get_txt_Milter_dns(name, timeout=5):
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"""Return a TXT record associated with a DNS name."""
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# Older pydns releases don't like a trailing dot.
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if name.endswith('.'):
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name = name[:-1]
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sess = Session()
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a = sess.dns(name.encode('idna'),'TXT')
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if a: return b''.join(a[0])
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return None
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# Prefer dnspython if it's there, otherwise use pydns.
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try:
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import dns.resolver
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_get_txt = get_txt_dnspython
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except ImportError:
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try:
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import DNS
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DNS.DiscoverNameServers()
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_get_txt = get_txt_pydns
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except:
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raise
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def get_txt(name, timeout=5):
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"""Return a TXT record associated with a DNS name.
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@param name: The bytestring domain name to look up.
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"""
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# pydns needs Unicode, but DKIM's d= is ASCII (already punycoded).
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try:
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unicode_name = name.decode('UTF-8')
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except UnicodeDecodeError:
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return None
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txt = _get_txt(unicode_name, timeout)
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if type(txt) is str:
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txt = txt.encode('utf-8')
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return txt
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