mirror of
https://github.com/mail-in-a-box/mailinabox.git
synced 2024-11-22 02:17:26 +00:00
494 lines
18 KiB
Python
Executable File
494 lines
18 KiB
Python
Executable File
# Creates DNS zone files for all of the domains of all of the mail users
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# and mail aliases and restarts nsd.
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########################################################################
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import os, os.path, urllib.parse, datetime, re, hashlib
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import rtyaml
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from mailconfig import get_mail_domains
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from utils import shell, load_env_vars_from_file
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def get_dns_domains(env):
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# What domains should we serve DNS for?
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domains = set()
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# Add all domain names in use by email users and mail aliases.
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domains |= get_mail_domains(env)
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# Ensure the PUBLIC_HOSTNAME is in that list if it is not a subdomain of
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# any other domain we manage. If it's a subdomain, having it be a separate
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# zone will confuse DNSSEC because it will be signed without having a DS
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# record at the parent.
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for d in domains:
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if env['PUBLIC_HOSTNAME'].endswith("." + d):
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break
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else:
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# No 'break' was executed, so it is not a subdomain of a domain
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# we know about. Thus add it.
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domains.add(env['PUBLIC_HOSTNAME'])
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# Make a nice and safe filename for each domain.
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zonefiles = []
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for domain in domains:
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zonefiles.append([domain, urllib.parse.quote(domain, safe='') + ".txt"])
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return zonefiles
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def do_dns_update(env):
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# What domains (and their zone filenames) should we build?
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zonefiles = get_dns_domains(env)
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# Write zone files.
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os.makedirs('/etc/nsd/zones', exist_ok=True)
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updated_domains = []
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for i, (domain, zonefile) in enumerate(zonefiles):
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# Build the records to put in the zone.
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records = build_zone(domain, zonefile, env)
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# See if the zone has changed, and if so update the serial number
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# and write the zone file.
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if not write_nsd_zone(domain, "/etc/nsd/zones/" + zonefile, records, env):
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# Zone was not updated. There were no changes.
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continue
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# If this is a .justtesting.email domain, then post the update.
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try:
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justtestingdotemail(domain, records)
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except:
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# Hmm. Might be a network issue. If we stop now, will we end
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# up in an inconsistent state? Let's just continue.
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pass
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# Mark that we just updated this domain.
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updated_domains.append(domain)
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# Sign the zone.
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#
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# Every time we sign the zone we get a new result, which means
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# we can't sign a zone without bumping the zone's serial number.
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# Thus we only sign a zone if write_nsd_zone returned True
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# indicating the zone changed, and thus it got a new serial number.
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# write_nsd_zone is smart enough to check if a zone's signature
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# is nearing experiation and if so it'll bump the serial number
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# and return True so we get a chance to re-sign it.
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sign_zone(domain, zonefile, env)
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# Now that all zones are signed (some might not have changed and so didn't
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# just get signed now, but were before) update the zone filename so nsd.conf
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# uses the signed file.
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for i in range(len(zonefiles)):
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zonefiles[i][1] += ".signed"
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# Write the main nsd.conf file.
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if write_nsd_conf(zonefiles):
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# Make sure updated_domains contains *something* if we wrote an updated
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# nsd.conf so that we know to restart nsd.
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if len(updated_domains) == 0:
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updated_domains.append("DNS configuration")
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# Kick nsd if anything changed.
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if len(updated_domains) > 0:
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shell('check_call', ["/usr/sbin/service", "nsd", "restart"])
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# Write the OpenDKIM configuration tables.
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write_opendkim_tables(zonefiles, env)
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# Kick opendkim.
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shell('check_call', ["/usr/sbin/service", "opendkim", "restart"])
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if len(updated_domains) == 0:
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# if nothing was updated (except maybe DKIM), don't show any output
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return ""
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else:
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return "updated: " + ",".join(updated_domains) + "\n"
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########################################################################
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def build_zone(domain, zonefile, env, with_ns=True):
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records = []
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# For top-level zones, define ourselves as the authoritative name server.
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if with_ns:
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records.append((None, "NS", "ns1.%s." % env["PUBLIC_HOSTNAME"]))
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records.append((None, "NS", "ns2.%s." % env["PUBLIC_HOSTNAME"]))
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records.append((None, "MX", "10 %s." % env["PUBLIC_HOSTNAME"]))
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records.append((None, "TXT", '"v=spf1 mx -all"'))
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# If PUBLIC_HOSTNAME is a subdomain of this domain, define it here.
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if env['PUBLIC_HOSTNAME'].endswith("." + domain):
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ph = env['PUBLIC_HOSTNAME'][0:-len("." + domain)]
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for child_qname, child_rtype, child_value in build_zone(env['PUBLIC_HOSTNAME'], None, env, with_ns=False):
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if child_qname == None:
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child_qname = ph
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else:
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child_qname += "." + ph
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records.append((child_qname, child_rtype, child_value))
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# In PUBLIC_HOSTNAME...
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if domain == env["PUBLIC_HOSTNAME"]:
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# Define ns1 and ns2.
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records.append(("ns1", "A", env["PUBLIC_IP"]))
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records.append(("ns2", "A", env["PUBLIC_IP"]))
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# Add a TLSA record for SMTP.
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records.append(("_25._tcp", "TLSA", build_tlsa_record(env)))
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def has_rec(qname, rtype):
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for rec in records:
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if rec[0] == qname and rec[1] == rtype:
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return True
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return False
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# The user may set other records that don't conflict with our settings.
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custom_zone_file = os.path.join(env['STORAGE_ROOT'], 'dns/custom', zonefile.replace(".txt", ".yaml")) if zonefile else None
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if zonefile and os.path.exists(custom_zone_file):
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custom_zone = rtyaml.load(open(custom_zone_file))
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for qname, value in custom_zone.items():
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if has_rec(qname, value): continue
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if isinstance(value, str):
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records.append((qname, "A", value))
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elif isinstance(value, dict):
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for rtype, value2 in value.items():
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if rtype == "TXT": value2 = "\"" + value2 + "\""
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records.append((qname, rtype, value2))
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# Add defaults if not overridden by the user's custom settings.
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if not has_rec(None, "A"): records.append((None, "A", env["PUBLIC_IP"]))
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if env.get('PUBLIC_IPV6') and not has_rec(None, "AAAA"): records.append((None, "AAAA", env["PUBLIC_IPV6"]))
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if not has_rec("www", "A"): records.append(("www", "A", env["PUBLIC_IP"]))
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if env.get('PUBLIC_IPV6') and not has_rec("www", "AAAA"): records.append(("www", "AAAA", env["PUBLIC_IPV6"]))
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# If OpenDKIM is in use..
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opendkim_record_file = os.path.join(env['STORAGE_ROOT'], 'mail/dkim/mail.txt')
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if os.path.exists(opendkim_record_file):
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# Append the DKIM TXT record to the zone as generated by OpenDKIM, after string formatting above.
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with open(opendkim_record_file) as orf:
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m = re.match(r"(\S+)\s+IN\s+TXT\s+(\(.*\))\s*;", orf.read(), re.S)
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records.append((m.group(1), "TXT", m.group(2)))
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# Append a DMARC record.
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records.append(("_dmarc", "TXT", '"v=DMARC1; p=quarantine"'))
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# Sort the records. The None records *must* go first. Otherwise it doesn't matter.
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records.sort(key = lambda rec : list(reversed(rec[0].split(".")) if rec[0] is not None else ""))
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return records
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########################################################################
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def build_tlsa_record(env):
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# A TLSA record in DNS specifies that connections on a port, e.g.
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# the SMTP port, must use TLS and the certificate must match a
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# particular certificate.
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#
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# Thanks to http://blog.huque.com/2012/10/dnssec-and-certificates.html
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# for explaining all of this!
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# Get the hex SHA256 of the DER-encoded server certificate:
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certder = shell("check_output", [
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"/usr/bin/openssl",
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"x509",
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"-in", os.path.join(env["STORAGE_ROOT"], "ssl", "ssl_certificate.pem"),
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"-outform", "DER"
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],
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return_bytes=True)
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certhash = hashlib.sha256(certder).hexdigest()
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# Specify the TLSA parameters:
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# 3: This is the certificate that the client should trust. No CA is needed.
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# 0: The whole certificate is matched.
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# 1: The certificate is SHA256'd here.
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return "3 0 1 " + certhash
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########################################################################
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def write_nsd_zone(domain, zonefile, records, env):
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# We set the administrative email address for every domain to domain_contact@[domain.com].
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# You should probably create an alias to your email address.
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# On the $ORIGIN line, there's typically a ';' comment at the end explaining
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# what the $ORIGIN line does. Any further data after the domain confuses
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# ldns-signzone, however. It used to say '; default zone domain'.
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zone = """
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$ORIGIN {domain}.
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$TTL 86400 ; default time to live
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@ IN SOA ns1.{primary_domain}. hostmaster.{primary_domain}. (
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__SERIAL__ ; serial number
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28800 ; Refresh
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7200 ; Retry
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864000 ; Expire
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86400 ; Min TTL
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)
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"""
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# Replace replacement strings.
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zone = zone.format(domain=domain, primary_domain=env["PUBLIC_HOSTNAME"])
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# Add records.
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for subdomain, querytype, value in records:
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if subdomain:
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zone += subdomain
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zone += "\tIN\t" + querytype + "\t"
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zone += value + "\n"
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# DNSSEC requires re-signing a zone periodically. That requires
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# bumping the serial number even if no other records have changed.
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# We don't see the DNSSEC records yet, so we have to figure out
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# if a re-signing is necessary so we can prematurely bump the
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# serial number.
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force_bump = False
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if not os.path.exists(zonefile + ".signed"):
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# No signed file yet. Shouldn't normally happen unless a box
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# is going from not using DNSSEC to using DNSSEC.
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force_bump = True
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else:
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# We've signed the domain. Check if we are close to the expiration
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# time of the signature. If so, we'll force a bump of the serial
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# number so we can re-sign it.
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with open(zonefile + ".signed") as f:
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signed_zone = f.read()
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expiration_times = re.findall(r"\sRRSIG\s+SOA\s+\d+\s+\d+\s\d+\s+(\d{14})", signed_zone)
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if len(expiration_times) == 0:
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# weird
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force_bump = True
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else:
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# All of the times should be the same, but if not choose the soonest.
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expiration_time = min(expiration_times)
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expiration_time = datetime.datetime.strptime(expiration_time, "%Y%m%d%H%M%S")
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if expiration_time - datetime.datetime.now() < datetime.timedelta(days=3):
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# We're within three days of the expiration, so bump serial & resign.
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force_bump = True
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# Set the serial number.
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serial = datetime.datetime.now().strftime("%Y%m%d00")
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if os.path.exists(zonefile):
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# If the zone already exists, is different, and has a later serial number,
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# increment the number.
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with open(zonefile) as f:
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existing_zone = f.read()
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m = re.search(r"(\d+)\s*;\s*serial number", existing_zone)
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if m:
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# Clear out the serial number in the existing zone file for the
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# purposes of seeing if anything *else* in the zone has changed.
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existing_serial = m.group(1)
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existing_zone = existing_zone.replace(m.group(0), "__SERIAL__ ; serial number")
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# If the existing zone is the same as the new zone (modulo the serial number),
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# there is no need to update the file. Unless we're forcing a bump.
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if zone == existing_zone and not force_bump:
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return False
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# If the existing serial is not less than a serial number
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# based on the current date plus 00, increment it. Otherwise,
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# the serial number is less than our desired new serial number
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# so we'll use the desired new number.
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if existing_serial >= serial:
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serial = str(int(existing_serial) + 1)
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zone = zone.replace("__SERIAL__", serial)
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# Write the zone file.
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with open(zonefile, "w") as f:
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f.write(zone)
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return True # file is updated
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########################################################################
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def write_nsd_conf(zonefiles):
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# Basic header.
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nsdconf = """
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server:
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hide-version: yes
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# identify the server (CH TXT ID.SERVER entry).
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identity: ""
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# The directory for zonefile: files.
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zonesdir: "/etc/nsd/zones"
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"""
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# Since we have bind9 listening on localhost for locally-generated
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# DNS queries that require a recursive nameserver, we must have
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# nsd listen only on public network interfaces. Those interfaces
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# may have addresses different from the public IP address that the
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# Internet sees this machine on. Get those interface addresses
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# from `hostname -i` (which omits all localhost addresses).
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for ipaddr in shell("check_output", ["/bin/hostname", "-I"]).strip().split(" "):
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nsdconf += " ip-address: %s\n" % ipaddr
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# Append the zones.
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for domain, zonefile in sorted(zonefiles):
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nsdconf += """
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zone:
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name: %s
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zonefile: %s
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""" % (domain, zonefile)
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# Check if the nsd.conf is changing. If it isn't changing,
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# return False to flag that no change was made.
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with open("/etc/nsd/nsd.conf") as f:
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if f.read() == nsdconf:
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return False
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with open("/etc/nsd/nsd.conf", "w") as f:
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f.write(nsdconf)
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return True
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########################################################################
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def sign_zone(domain, zonefile, env):
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dnssec_keys = load_env_vars_from_file(os.path.join(env['STORAGE_ROOT'], 'dns/dnssec/keys.conf'))
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# In order to use the same keys for all domains, we have to generate
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# a new .key file with a DNSSEC record for the specific domain. We
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# can reuse the same key, but it won't validate without a DNSSEC
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# record specifically for the domain.
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#
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# Copy the .key and .private files to /tmp to patch them up.
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#
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# Use os.umask and open().write() to securely create a copy that only
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# we (root) can read.
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files_to_kill = []
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for key in ("KSK", "ZSK"):
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if dnssec_keys.get(key, "").strip() == "": raise Exception("DNSSEC is not properly set up.")
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oldkeyfn = os.path.join(env['STORAGE_ROOT'], 'dns/dnssec/' + dnssec_keys[key])
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newkeyfn = '/tmp/' + dnssec_keys[key].replace("_domain_", domain)
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dnssec_keys[key] = newkeyfn
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for ext in (".private", ".key"):
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if not os.path.exists(oldkeyfn + ext): raise Exception("DNSSEC is not properly set up.")
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with open(oldkeyfn + ext, "r") as fr:
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keydata = fr.read()
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keydata = keydata.replace("_domain_", domain) # trick ldns-signkey into letting our generic key be used by this zone
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fn = newkeyfn + ext
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prev_umask = os.umask(0o77) # ensure written file is not world-readable
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try:
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with open(fn, "w") as fw:
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fw.write(keydata)
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finally:
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os.umask(prev_umask) # other files we write should be world-readable
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files_to_kill.append(fn)
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# Do the signing.
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expiry_date = (datetime.datetime.now() + datetime.timedelta(days=30)).strftime("%Y%m%d")
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shell('check_call', ["/usr/bin/ldns-signzone",
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# expire the zone after 30 days
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"-e", expiry_date,
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# use NSEC3
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"-n",
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# zonefile to sign
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"/etc/nsd/zones/" + zonefile,
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# keys to sign with (order doesn't matter -- it'll figure it out)
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dnssec_keys["KSK"],
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dnssec_keys["ZSK"],
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])
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# Create a DS record based on the patched-up key files. The DS record is specific to the
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# zone being signed, so we can't use the .ds files generated when we created the keys.
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# The DS record points to the KSK only. Write this next to the zone file so we can
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# get it later to give to the user with instructions on what to do with it.
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rr_ds = shell('check_output', ["/usr/bin/ldns-key2ds",
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"-n", # output to stdout
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"-2", # SHA256
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dnssec_keys["KSK"] + ".key"
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])
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with open("/etc/nsd/zones/" + zonefile + ".ds", "w") as f:
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f.write(rr_ds)
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# Remove our temporary file.
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for fn in files_to_kill:
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os.unlink(fn)
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########################################################################
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def get_ds_records(env):
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zonefiles = get_dns_domains(env)
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ret = ""
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for domain, zonefile in zonefiles:
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fn = "/etc/nsd/zones/" + zonefile + ".ds"
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if os.path.exists(fn):
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with open(fn, "r") as fr:
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ret += fr.read().strip() + "\n"
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return ret
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########################################################################
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def write_opendkim_tables(zonefiles, env):
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# Append a record to OpenDKIM's KeyTable and SigningTable for each domain.
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#
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# The SigningTable maps email addresses to signing information. The KeyTable
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# maps specify the hostname, the selector, and the path to the private key.
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#
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# DKIM ADSP and DMARC both only support policies where the signing domain matches
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# the From address, so the KeyTable must specify that the signing domain for a
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# sender matches the sender's domain.
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#
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# In SigningTable, we map every email address to a key record named after the domain.
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# Then we specify for the key record its domain, selector, and key.
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opendkim_key_file = os.path.join(env['STORAGE_ROOT'], 'mail/dkim/mail.private')
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if not os.path.exists(opendkim_key_file): return
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with open("/etc/opendkim/KeyTable", "w") as f:
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f.write("\n".join(
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"{domain} {domain}:mail:{key_file}".format(domain=domain, key_file=opendkim_key_file)
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for domain, zonefile in zonefiles
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))
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with open("/etc/opendkim/SigningTable", "w") as f:
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f.write("\n".join(
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"*@{domain} {domain}".format(domain=domain)
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for domain, zonefile in zonefiles
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))
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########################################################################
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def justtestingdotemail(domain, records):
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# If the domain is a subdomain of justtesting.email, which we own,
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# automatically populate the zone where it is set up on dns4e.com.
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# Ideally if dns4e.com supported NS records we would just have it
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# delegate DNS to us, but instead we will populate the whole zone.
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|
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import subprocess, json, urllib.parse
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|
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if not domain.endswith(".justtesting.email"):
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return
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for subdomain, querytype, value in records:
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if querytype in ("NS",): continue
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if subdomain in ("www", "ns1", "ns2"): continue # don't do unnecessary things
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|
|
|
if subdomain == None:
|
|
subdomain = domain
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else:
|
|
subdomain = subdomain + "." + domain
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|
|
|
if querytype == "TXT":
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|
# nsd requires parentheses around txt records with multiple parts,
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|
# but DNS4E requires there be no parentheses; also it goes into
|
|
# nsd with a newline and a tab, which we replace with a space here
|
|
value = re.sub("^\s*\(\s*([\w\W]*)\)", r"\1", value)
|
|
value = re.sub("\s+", " ", value)
|
|
else:
|
|
continue
|
|
|
|
print("Updating DNS for %s/%s..." % (subdomain, querytype))
|
|
resp = json.loads(subprocess.check_output([
|
|
"curl",
|
|
"-s",
|
|
"https://api.dns4e.com/v7/%s/%s" % (urllib.parse.quote(subdomain), querytype.lower()),
|
|
"--user", "2ddbd8e88ed1495fa0ec:A97TDJV26CVUJS6hqAs0CKnhj4HvjTM7MwAAg8xb",
|
|
"--data", "record=%s" % urllib.parse.quote(value),
|
|
]).decode("utf8"))
|
|
print("\t...", resp.get("message", "?"))
|