apps/inbound-mail/src/python/dkim/dnsplug.py - next - githubmirror/novu

apps/inbound-mail/src/python/dkim/dnsplug.py
89 строк3 KB
George Djabarov
fix(root): replace inbound-mail vendored pydns with py3dns for Python 3 fixes NV-8233 (#11848)
08 июл 2026, 01:21
08 июл 2026, 01:2124a419d
# This software is provided 'as-is', without any express or implied
# warranty.  In no event will the author be held liable for any damages
# arising from the use of this software.
#
# Permission is granted to anyone to use this software for any purpose,
# including commercial applications, and to alter it and redistribute it
# freely, subject to the following restrictions:
#
# 1. The origin of this software must not be misrepresented; you must not
#    claim that you wrote the original software. If you use this software
#    in a product, an acknowledgment in the product documentation would be
#    appreciated but is not required.
# 2. Altered source versions must be plainly marked as such, and must not be
#    misrepresented as being the original software.
# 3. This notice may not be removed or altered from any source distribution.
#
# Copyright (c) 2008 Greg Hewgill http://hewgill.com
#
# This has been modified from the original software.
# Copyright (c) 2011 William Grant <me@williamgrant.id.au>


__all__ = [
    'get_txt'
    ]


def get_txt_dnspython(name):
    """Return a TXT record associated with a DNS name."""
    try:
      a = dns.resolver.query(name, dns.rdatatype.TXT,raise_on_no_answer=False)
      for r in a.response.answer:
          if r.rdtype == dns.rdatatype.TXT:
              return b"".join(r.items[0].strings)
    except dns.resolver.NXDOMAIN: pass
    return None


def get_txt_pydns(name):
    """Return a TXT record associated with a DNS name."""
    # Older pydns releases don't like a trailing dot.
    if name.endswith('.'):
        name = name[:-1]
    response = DNS.DnsRequest(name, qtype='txt').req()
    # The answer section may contain CNAME records (whose data is a str)
    # before the TXT record, e.g. when the DKIM selector is CNAME-delegated.
    for answer in response.answers:
        if answer['typename'].lower() == 'txt':
            return b''.join(answer['data'])
    return None

def get_txt_Milter_dns(name):
    """Return a TXT record associated with a DNS name."""
    # Older pydns releases don't like a trailing dot.
    if name.endswith('.'):
        name = name[:-1]
    sess = Session()
    a = sess.dns(name,'TXT')
    if a: return b''.join(a[0])
    return None

# Prefer dnspython if it's there, otherwise use pydns.
try:
    import dns.resolver
    _get_txt = get_txt_dnspython
except ImportError:
    try:
        from Milter.dns import Session
        _get_txt = get_txt_Milter_dns
    except ImportError:
        import DNS
        DNS.DiscoverNameServers()
        _get_txt = get_txt_pydns

def get_txt(name):
    """Return a TXT record associated with a DNS name.

    @param name: The bytestring domain name to look up.
    """
    # pydns needs Unicode, but DKIM's d= is ASCII (already punycoded).
    try:
        unicode_name = name.decode('ascii')
    except UnicodeDecodeError:
        return None
    txt = _get_txt(unicode_name)
    # py3dns and dnspython already return bytes; only str needs encoding.
    if isinstance(txt, str):
      txt = txt.encode('utf-8')
    return txt