mirror of
https://gitlab.isc.org/isc-projects/bind9.git
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348 lines
12 KiB
Python
Executable File
348 lines
12 KiB
Python
Executable File
############################################################################
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# Copyright (C) Internet Systems Consortium, Inc. ("ISC")
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#
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# This Source Code Form is subject to the terms of the Mozilla Public
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# License, v. 2.0. If a copy of the MPL was not distributed with this
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# file, You can obtain one at http://mozilla.org/MPL/2.0/.
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#
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# See the COPYRIGHT file distributed with this work for additional
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# information regarding copyright ownership.
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############################################################################
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############################################################################
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# ans.py: See README.anspy for details.
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############################################################################
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from __future__ import print_function
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import os
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import sys
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import signal
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import socket
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import select
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from datetime import datetime, timedelta
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import functools
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import dns, dns.message, dns.query
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from dns.rdatatype import *
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from dns.rdataclass import *
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from dns.rcode import *
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from dns.name import *
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############################################################################
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# set up the RRs to be returned in the next answer
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#
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# the message contains up to two pipe-separated ('|') fields.
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#
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# the first field of the message is a comma-separated list
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# of actions indicating what to put into the answer set
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# (e.g., a dname, a cname, another cname, etc)
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#
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# supported actions:
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# - cname (cname from the current name to a new one in the same domain)
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# - dname (dname to a new domain, plus a synthesized cname)
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# - xname ("external" cname, to a new name in a new domain)
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#
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# example: xname, dname, cname represents a CNAME to an external
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# domain which is then answered by a DNAME and synthesized
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# CNAME pointing to yet another domain, which is then answered
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# by a CNAME within the same domain, and finally an answer
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# to the query. each RR in the answer set has a corresponding
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# RRSIG. these signatures are not valid, but will exercise the
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# response parser.
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#
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# the second field is a comma-separated list of which RRs in the
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# answer set to include in the answer, in which order. if prepended
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# with 's', the number indicates which signature to include.
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#
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# examples: for the answer set "cname, cname, cname", an rr set
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# '1, s1, 2, s2, 3, s3, 4, s4' indicates that all four RRs should
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# be included in the answer, with siagntures, in the original
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# order, while 4, s4, 3, s3, 2, s2, 1, s1' indicates the order
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# should be reversed, 's3, s3, s3, s3' indicates that the third
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# RRSIG should be repeated four times and everything else should
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# be omitted, and so on.
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#
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# if there is no second field (i.e., no pipe symbol appears in
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# the line) , the default is to send all answers and signatures.
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# if a pipe symbol exists but the second field is empty, then
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# nothing is sent at all.
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############################################################################
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actions = []
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rrs = []
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def ctl_channel(msg):
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global actions, rrs
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msg = msg.splitlines().pop(0)
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print ('received control message: %s' % msg)
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msg = msg.split(b'|')
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if len(msg) == 0:
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return
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actions = [x.strip() for x in msg[0].split(b',')]
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n = functools.reduce(lambda n, act: (n + (2 if act == b'dname' else 1)), [0] + actions)
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if len(msg) == 1:
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rrs = []
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for i in range(n):
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for b in [False, True]:
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rrs.append((i, b))
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return
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rlist = [x.strip() for x in msg[1].split(b',')]
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rrs = []
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for item in rlist:
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if item[0] == b's'[0]:
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i = int(item[1:].strip()) - 1
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if i > n:
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print ('invalid index %d' + (i + 1))
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continue
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rrs.append((int(item[1:]) - 1, True))
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else:
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i = int(item) - 1
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if i > n:
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print ('invalid index %d' % (i + 1))
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continue
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rrs.append((i, False))
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############################################################################
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# Respond to a DNS query.
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############################################################################
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def create_response(msg):
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m = dns.message.from_wire(msg)
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qname = m.question[0].name.to_text()
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labels = qname.lower().split('.')
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wantsigs = True if m.ednsflags & dns.flags.DO else False
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# get qtype
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rrtype = m.question[0].rdtype
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typename = dns.rdatatype.to_text(rrtype)
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# for 'www.example.com.'...
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# - name is 'www'
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# - domain is 'example.com.'
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# - sld is 'example'
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# - tld is 'com.'
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name = labels.pop(0)
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domain = '.'.join(labels)
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sld = labels.pop(0)
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tld = '.'.join(labels)
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print ('query: ' + qname + '/' + typename)
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print ('domain: ' + domain)
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# default answers, depending on QTYPE.
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# currently only A, AAAA, TXT and NS are supported.
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ttl = 86400
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additionalA = '10.53.0.4'
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additionalAAAA = 'fd92:7065:b8e:ffff::4'
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if typename == 'A':
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final = '10.53.0.4'
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elif typename == 'AAAA':
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final = 'fd92:7065:b8e:ffff::4'
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elif typename == 'TXT':
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final = 'Some\ text\ here'
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elif typename == 'NS':
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domain = qname
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final = ('ns1.%s' % domain)
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else:
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final = None
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# RRSIG rdata - won't validate but will exercise response parsing
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t = datetime.now()
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delta = timedelta(30)
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t1 = t - delta
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t2 = t + delta
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inception=t1.strftime('%Y%m%d000000')
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expiry=t2.strftime('%Y%m%d000000')
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sigdata='OCXH2De0yE4NMTl9UykvOsJ4IBGs/ZIpff2rpaVJrVG7jQfmj50otBAp A0Zo7dpBU4ofv0N/F2Ar6LznCncIojkWptEJIAKA5tHegf/jY39arEpO cevbGp6DKxFhlkLXNcw7k9o7DSw14OaRmgAjXdTFbrl4AiAa0zAttFko Tso='
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# construct answer set.
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answers = []
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sigs = []
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curdom = domain
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curname = name
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i = 0
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for action in actions:
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if name != 'test':
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continue
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if action == b'xname':
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owner = curname + '.' + curdom
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newname = 'cname%d' % i
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i += 1
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newdom = 'domain%d.%s' % (i, tld)
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i += 1
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target = newname + '.' + newdom
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print ('add external CNAME %s to %s' % (owner, target))
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answers.append(dns.rrset.from_text(owner, ttl, IN, CNAME, target))
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rrsig = 'CNAME 5 3 %d %s %s 12345 %s %s' % \
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(ttl, expiry, inception, domain, sigdata)
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print ('add external RRISG(CNAME) %s to %s' % (owner, target))
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sigs.append(dns.rrset.from_text(owner, ttl, IN, RRSIG, rrsig))
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curname = newname
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curdom = newdom
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continue
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if action == b'cname':
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owner = curname + '.' + curdom
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newname = 'cname%d' % i
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target = newname + '.' + curdom
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i += 1
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print ('add CNAME %s to %s' % (owner, target))
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answers.append(dns.rrset.from_text(owner, ttl, IN, CNAME, target))
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rrsig = 'CNAME 5 3 %d %s %s 12345 %s %s' % \
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(ttl, expiry, inception, domain, sigdata)
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print ('add RRSIG(CNAME) %s to %s' % (owner, target))
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sigs.append(dns.rrset.from_text(owner, ttl, IN, RRSIG, rrsig))
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curname = newname
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continue
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if action == b'dname':
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owner = curdom
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newdom = 'domain%d.%s' % (i, tld)
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i += 1
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print ('add DNAME %s to %s' % (owner, newdom))
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answers.append(dns.rrset.from_text(owner, ttl, IN, DNAME, newdom))
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rrsig = 'DNAME 5 3 %d %s %s 12345 %s %s' % \
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(ttl, expiry, inception, domain, sigdata)
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print ('add RRSIG(DNAME) %s to %s' % (owner, newdom))
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sigs.append(dns.rrset.from_text(owner, ttl, IN, RRSIG, rrsig))
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owner = curname + '.' + curdom
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target = curname + '.' + newdom
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print ('add synthesized CNAME %s to %s' % (owner, target))
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answers.append(dns.rrset.from_text(owner, ttl, IN, CNAME, target))
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rrsig = 'CNAME 5 3 %d %s %s 12345 %s %s' % \
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(ttl, expiry, inception, domain, sigdata)
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print ('add synthesized RRSIG(CNAME) %s to %s' % (owner, target))
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sigs.append(dns.rrset.from_text(owner, ttl, IN, RRSIG, rrsig))
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curdom = newdom
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continue
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# now add the final answer
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owner = curname + '.' + curdom
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answers.append(dns.rrset.from_text(owner, ttl, IN, rrtype, final))
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rrsig = '%s 5 3 %d %s %s 12345 %s %s' % \
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(typename, ttl, expiry, inception, domain, sigdata)
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sigs.append(dns.rrset.from_text(owner, ttl, IN, RRSIG, rrsig))
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# prepare the response and convert to wire format
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r = dns.message.make_response(m)
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if name != 'test':
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r.answer.append(answers[-1])
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if wantsigs:
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r.answer.append(sigs[-1])
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else:
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for (i, sig) in rrs:
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if sig and not wantsigs:
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continue
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elif sig:
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r.answer.append(sigs[i])
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else:
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r.answer.append(answers[i])
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if typename != 'NS':
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r.authority.append(dns.rrset.from_text(domain, ttl, IN, "NS",
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("ns1.%s" % domain)))
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r.additional.append(dns.rrset.from_text(('ns1.%s' % domain), 86400,
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IN, A, additionalA))
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r.additional.append(dns.rrset.from_text(('ns1.%s' % domain), 86400,
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IN, AAAA, additionalAAAA))
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r.flags |= dns.flags.AA
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r.use_edns()
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return r.to_wire()
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def sigterm(signum, frame):
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print ("Shutting down now...")
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os.remove('ans.pid')
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running = False
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sys.exit(0)
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############################################################################
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# Main
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#
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# Set up responder and control channel, open the pid file, and start
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# the main loop, listening for queries on the query channel or commands
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# on the control channel and acting on them.
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############################################################################
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ip4 = "10.53.0.4"
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ip6 = "fd92:7065:b8e:ffff::4"
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try: port=int(os.environ['PORT'])
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except: port=5300
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try: ctrlport=int(os.environ['EXTRAPORT1'])
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except: ctrlport=5300
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query4_socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
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query4_socket.bind((ip4, port))
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havev6 = True
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try:
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query6_socket = socket.socket(socket.AF_INET6, socket.SOCK_DGRAM)
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try:
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query6_socket.bind((ip6, port))
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except:
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query6_socket.close()
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havev6 = False
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except:
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havev6 = False
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ctrl_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
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ctrl_socket.bind((ip4, ctrlport))
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ctrl_socket.listen(5)
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signal.signal(signal.SIGTERM, sigterm)
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f = open('ans.pid', 'w')
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pid = os.getpid()
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print (pid, file=f)
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f.close()
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running = True
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print ("Listening on %s port %d" % (ip4, port))
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if havev6:
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print ("Listening on %s port %d" % (ip6, port))
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print ("Control channel on %s port %d" % (ip4, ctrlport))
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print ("Ctrl-c to quit")
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if havev6:
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input = [query4_socket, query6_socket, ctrl_socket]
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else:
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input = [query4_socket, ctrl_socket]
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while running:
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try:
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inputready, outputready, exceptready = select.select(input, [], [])
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except select.error as e:
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break
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except socket.error as e:
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break
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except KeyboardInterrupt:
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break
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for s in inputready:
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if s == ctrl_socket:
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# Handle control channel input
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conn, addr = s.accept()
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print ("Control channel connected")
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while True:
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msg = conn.recv(65535)
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if not msg:
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break
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ctl_channel(msg)
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conn.close()
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if s == query4_socket or s == query6_socket:
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print ("Query received on %s" %
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(ip4 if s == query4_socket else ip6))
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# Handle incoming queries
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msg = s.recvfrom(65535)
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rsp = create_response(msg[0])
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if rsp:
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s.sendto(rsp, msg[1])
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if not running:
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break
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