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101 lines
2.3 KiB
Python
101 lines
2.3 KiB
Python
from typing import Optional
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import dns.resolver
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def _get_dns_resolver():
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my_resolver = dns.resolver.Resolver()
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# 1.1.1.1 is CloudFlare's public DNS server
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my_resolver.nameservers = ["1.1.1.1"]
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return my_resolver
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def get_cname_record(hostname) -> Optional[str]:
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"""Return the CNAME record if exists for a domain"""
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try:
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answers = _get_dns_resolver().query(hostname, "CNAME")
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except Exception:
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return None
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for a in answers:
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return a
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return None
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def get_mx_domains(hostname) -> [(int, str)]:
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"""return list of (priority, domain name).
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domain name ends with a "." at the end.
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"""
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try:
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answers = _get_dns_resolver().query(hostname, "MX")
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except Exception:
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return []
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ret = []
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for a in answers:
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record = a.to_text() # for ex '20 alt2.aspmx.l.google.com.'
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parts = record.split(" ")
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ret.append((int(parts[0]), parts[1]))
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return ret
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_include_spf = "include:"
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def get_spf_domain(hostname) -> [str]:
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"""return all domains listed in *include:*"""
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try:
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answers = _get_dns_resolver().query(hostname, "TXT")
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except Exception:
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return []
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ret = []
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for a in answers: # type: dns.rdtypes.ANY.TXT.TXT
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for record in a.strings:
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record = record.decode() # record is bytes
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if record.startswith("v=spf1"):
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parts = record.split(" ")
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for part in parts:
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if part.startswith(_include_spf):
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ret.append(part[part.find(_include_spf) + len(_include_spf) :])
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return ret
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def get_txt_record(hostname) -> [str]:
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try:
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answers = _get_dns_resolver().query(hostname, "TXT")
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except Exception:
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return []
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ret = []
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for a in answers: # type: dns.rdtypes.ANY.TXT.TXT
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ret.append(a)
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return ret
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def get_dkim_record(hostname) -> str:
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"""query the dkim._domainkey.{hostname} record and returns its value"""
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try:
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answers = _get_dns_resolver().query(f"dkim._domainkey.{hostname}", "TXT")
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except Exception:
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return ""
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ret = []
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for a in answers: # type: dns.rdtypes.ANY.TXT.TXT
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for record in a.strings:
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record = record.decode() # record is bytes
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ret.append(record)
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return "".join(ret)
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