From: Štěpán Balážik Date: Thu, 25 Dec 2025 16:03:20 +0000 (+0100) Subject: Reimplement 'resolver/ans8' server using AsyncDnsServer X-Git-Tag: v9.21.18~11^2~2 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=8f2526a27d9dfef46ef1ef26a971cc928c6c0f08;p=thirdparty%2Fbind9.git Reimplement 'resolver/ans8' server using AsyncDnsServer Ensure packet-for-packet compatibility with the old server. --- diff --git a/bin/tests/system/resolver/ans8/ans.pl b/bin/tests/system/resolver/ans8/ans.pl deleted file mode 100644 index a3d06b67d65..00000000000 --- a/bin/tests/system/resolver/ans8/ans.pl +++ /dev/null @@ -1,177 +0,0 @@ -#!/usr/bin/perl - -# Copyright (C) Internet Systems Consortium, Inc. ("ISC") -# -# SPDX-License-Identifier: MPL-2.0 -# -# This Source Code Form is subject to the terms of the Mozilla Public -# License, v. 2.0. If a copy of the MPL was not distributed with this -# file, you can obtain one at https://mozilla.org/MPL/2.0/. -# -# See the COPYRIGHT file distributed with this work for additional -# information regarding copyright ownership. - -use IO::File; -use IO::Socket; -use Data::Dumper; -use Net::DNS; -use Net::DNS::Packet; -use strict; - -# Ignore SIGPIPE so we won't fail if peer closes a TCP socket early -local $SIG{PIPE} = 'IGNORE'; - -# Flush logged output after every line -local $| = 1; - -my $server_addr = "10.53.0.8"; - -my $localport = int($ENV{'PORT'}); -if (!$localport) { $localport = 5300; } - -my $udpsock = IO::Socket::INET->new(LocalAddr => "$server_addr", - LocalPort => $localport, Proto => "udp", Reuse => 1) or die "$!"; -my $tcpsock = IO::Socket::INET->new(LocalAddr => "$server_addr", - LocalPort => $localport, Proto => "tcp", Listen => 5, Reuse => 1) or die "$!"; - -print "listening on $server_addr:$localport.\n"; - -my $pidf = new IO::File "ans.pid", "w" or die "cannot open pid file: $!"; -print $pidf "$$\n" or die "cannot write pid file: $!"; -$pidf->close or die "cannot close pid file: $!";; -sub rmpid { unlink "ans.pid"; exit 1; }; - -$SIG{INT} = \&rmpid; -$SIG{TERM} = \&rmpid; - -sub handleUDP { - my ($buf) = @_; - my $request; - - if ($Net::DNS::VERSION > 0.68) { - $request = new Net::DNS::Packet(\$buf, 0); - $@ and die $@; - } else { - my $err; - ($request, $err) = new Net::DNS::Packet(\$buf, 0); - $err and die $err; - } - - my @questions = $request->question; - my $qname = $questions[0]->qname; - my $qtype = $questions[0]->qtype; - my $qclass = $questions[0]->qclass; - my $id = $request->header->id; - - my $response = new Net::DNS::Packet($qname, $qtype, $qclass); - $response->header->qr(1); - $response->header->aa(1); - $response->header->tc(0); - $response->header->id($id); - - # Responses to queries for no-questions/NS and ns.no-questions/A are - # _not_ malformed or truncated. - if ($qname eq "no-questions" && $qtype eq "NS") { - $response->push("answer", new Net::DNS::RR($qname . " 300 NS ns.no-questions")); - $response->push("additional", new Net::DNS::RR("ns.no-questions. 300 A 10.53.0.8")); - return $response->data; - } elsif ($qname eq "ns.no-questions") { - $response->push("answer", new Net::DNS::RR($qname . " 300 A 10.53.0.8")) - if ($qtype eq "A"); - return $response->data; - } elsif ($qname =~ /\.formerr-to-all$/) { - $response->header->rcode("FORMERR"); - return $response->data; - } - - # don't use Net::DNS to construct the header only reply as early - # versions just get it completely wrong. - - if ($qname eq "truncated.no-questions") { - # QR, AA, TC: forces TCP retry - return (pack("nnnnnn", $id, 0x8600, 0, 0, 0, 0)); - } elsif ($qname eq "tcpalso.no-questions") { - # QR, REFUSED: forces TCP retry - return (pack("nnnnnn", $id, 0x8205, 0, 0, 0, 0)); - } - # QR, AA - return (pack("nnnnnn", $id, 0x8400, 0, 0, 0, 0)); -} - -sub handleTCP { - my ($buf) = @_; - my $request; - - if ($Net::DNS::VERSION > 0.68) { - $request = new Net::DNS::Packet(\$buf, 0); - $@ and die $@; - } else { - my $err; - ($request, $err) = new Net::DNS::Packet(\$buf, 0); - $err and die $err; - } - - my @questions = $request->question; - my $qname = $questions[0]->qname; - my $qtype = $questions[0]->qtype; - my $qclass = $questions[0]->qclass; - my $id = $request->header->id; - - my @results = (); - my $response = new Net::DNS::Packet($qname, $qtype, $qclass); - - $response->header->qr(1); - $response->header->aa(1); - $response->header->id($id); - $response->push("answer", new Net::DNS::RR("$qname 300 A 1.2.3.4")); - - if ($qname eq "tcpalso.no-questions") { - # for this qname we also return a bad reply over TCP - # QR, REFUSED, no question section - push (@results, pack("nnnnnn", $id, 0x8005, 0, 0, 0, 0)); - } else { - push(@results, $response->data); - } - - return \@results; -} - -# Main -my $rin; -my $rout; -for (;;) { - $rin = ''; - vec($rin, fileno($tcpsock), 1) = 1; - vec($rin, fileno($udpsock), 1) = 1; - - select($rout = $rin, undef, undef, undef); - - if (vec($rout, fileno($udpsock), 1)) { - printf "UDP request\n"; - my $buf; - $udpsock->recv($buf, 512); - my $result = handleUDP($buf); - my $num_chars = $udpsock->send($result); - print " Sent $num_chars bytes via UDP\n"; - } elsif (vec($rout, fileno($tcpsock), 1)) { - my $conn = $tcpsock->accept; - my $buf; - for (;;) { - my $lenbuf; - my $n = $conn->sysread($lenbuf, 2); - last unless $n == 2; - my $len = unpack("n", $lenbuf); - $n = $conn->sysread($buf, $len); - last unless $n == $len; - print "TCP request\n"; - my $result = handleTCP($buf); - foreach my $response (@$result) { - $len = length($response); - $n = $conn->syswrite(pack("n", $len), 2); - $n = $conn->syswrite($response, $len); - print " Sent: $n chars via TCP\n"; - } - } - $conn->close; - } -} diff --git a/bin/tests/system/resolver/ans8/ans.py b/bin/tests/system/resolver/ans8/ans.py new file mode 100644 index 00000000000..25eac4247f6 --- /dev/null +++ b/bin/tests/system/resolver/ans8/ans.py @@ -0,0 +1,144 @@ +""" +Copyright (C) Internet Systems Consortium, Inc. ("ISC") + +SPDX-License-Identifier: MPL-2.0 + +This Source Code Form is subject to the terms of the Mozilla Public +License, v. 2.0. If a copy of the MPL was not distributed with this +file, you can obtain one at https://mozilla.org/MPL/2.0/. + +See the COPYRIGHT file distributed with this work for additional +information regarding copyright ownership. +""" + +import abc + +from typing import AsyncGenerator + +import dns.flags +import dns.message +import dns.rcode +import dns.rdatatype + +from isctest.asyncserver import ( + AsyncDnsServer, + DnsResponseSend, + DnsProtocol, + DomainHandler, + QnameHandler, + QnameQtypeHandler, + QueryContext, + ResponseHandler, + StaticResponseHandler, +) + +from resolver_ans import rrset + + +class HeaderOnlyHandler(ResponseHandler): + """ + Return an empty DNS message with only header flags set. + """ + + @property + @abc.abstractmethod + def flags(self) -> dns.flags.Flag: + raise NotImplementedError + + @property + def rcode(self) -> dns.rcode.Rcode: + return dns.rcode.NOERROR + + async def get_responses( + self, qctx: QueryContext + ) -> AsyncGenerator[DnsResponseSend, None]: + message = dns.message.Message(id=qctx.query.id) + message.use_edns(False) + message.flags = self.flags + message.set_rcode(self.rcode) + yield DnsResponseSend(message, acknowledge_hand_rolled_response=True) + + +class RefusedOnTcpHandler(QnameHandler, HeaderOnlyHandler): + qnames = ["tcpalso.no-questions."] + flags = dns.flags.QR + rcode = dns.rcode.REFUSED + + def match(self, qctx: QueryContext) -> bool: + return qctx.protocol == DnsProtocol.TCP and super().match(qctx) + + +class TcpFallbackHandler(ResponseHandler): + def match(self, qctx: QueryContext) -> bool: + return qctx.protocol == DnsProtocol.TCP + + async def get_responses( + self, qctx: QueryContext + ) -> AsyncGenerator[DnsResponseSend, None]: + qctx.response.answer.append(rrset(qctx.qname, dns.rdatatype.A, "1.2.3.4")) + yield DnsResponseSend(qctx.response) + + +class FormerrToAllHandler(DomainHandler, StaticResponseHandler): + domains = ["formerr-to-all."] + rcode = dns.rcode.FORMERR + + +class NoQuestionsNSHandler(QnameQtypeHandler, StaticResponseHandler): + qnames = ["no-questions."] + qtypes = [dns.rdatatype.NS] + answer = [rrset(qnames[0], dns.rdatatype.NS, f"ns.{qnames[0]}")] + additional = [rrset(f"ns.{qnames[0]}", dns.rdatatype.A, "10.53.0.8")] + + +class NsNoQuestionsAHandler(QnameHandler): + qnames = ["ns.no-questions."] + + async def get_responses( + self, qctx: QueryContext + ) -> AsyncGenerator[DnsResponseSend, None]: + if qctx.qtype == dns.rdatatype.A: + a_rrset = rrset(qctx.qname, dns.rdatatype.A, "10.53.0.8") + qctx.response.answer.append(a_rrset) + yield DnsResponseSend(qctx.response) + + +class TcpalsoNoQuestionsHandler(QnameHandler, HeaderOnlyHandler): + qnames = ["tcpalso.no-questions."] + flags = dns.flags.QR | dns.flags.TC + rcode = dns.rcode.REFUSED + + +class TruncatedNoQuestionsHandler(QnameHandler, HeaderOnlyHandler): + qnames = ["truncated.no-questions."] + flags = dns.flags.QR | dns.flags.AA | dns.flags.TC + + +class FallbackHandler(HeaderOnlyHandler): + flags = dns.flags.QR | dns.flags.AA + + +def main() -> None: + server = AsyncDnsServer(default_aa=True, default_rcode=dns.rcode.NOERROR) + + # Install TCP handlers first so they take precedence + server.install_response_handlers( + RefusedOnTcpHandler(), + TcpFallbackHandler(), + ) + + # Install UDP handlers + server.install_response_handlers( + FormerrToAllHandler(), + NoQuestionsNSHandler(), + NsNoQuestionsAHandler(), + TcpalsoNoQuestionsHandler(), + TruncatedNoQuestionsHandler(), + ) + server.install_response_handler(FallbackHandler()) + + server.run() + + +if __name__ == "__main__": + main()