From: Štěpán Balážik Date: Tue, 4 Aug 2026 11:11:57 +0000 (+0200) Subject: Reimplement 'reclimit/ans2' server using ControllableAsyncServer X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=8e026321dede00dc64324470d414839c5a656369;p=thirdparty%2Fbind9.git Reimplement 'reclimit/ans2' server using ControllableAsyncServer Replace the Perl implementation with a Python one. Two behaviors of the old server are dropped: the responses driving the NS explosion are no longer truncated to 512 bytes, which only mattered for builds without IPv6 support, and the AA flag is only cleared on referrals rather than on every response with an empty answer section. --- diff --git a/bin/tests/system/reclimit/ans2/ans.pl b/bin/tests/system/reclimit/ans2/ans.pl deleted file mode 100644 index 4576951d7cc..00000000000 --- a/bin/tests/system/reclimit/ans2/ans.pl +++ /dev/null @@ -1,235 +0,0 @@ -#!/usr/bin/env 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 strict; -use warnings; - -use IO::File; -use IO::Socket; -use Net::DNS; - -my $localaddr = "10.53.0.2"; -my $limit = getlimit(); -my $no_more_waiting = 0; -my @delayed_response; -my $timeout; - -my $localport = int($ENV{'PORT'}); -if (!$localport) { $localport = 5300; } - -my $udpsock = IO::Socket::INET->new(LocalAddr => "$localaddr", - LocalPort => $localport, Proto => "udp", Reuse => 1) or die "$!"; - -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; - -my $count = 0; -my $send_response = 0; - -sub getlimit { - if ( -e "ans.limit") { - open(FH, "<", "ans.limit"); - my $line = ; - chomp $line; - close FH; - if ($line =~ /^\d+$/) { - return $line; - } - } - - return 0; -} - -# If $wait == 0 is returned, returned reply will be sent immediately. -# If $wait == 1 is returned, sending the returned reply might be delayed; see -# comments inside handle_UDP() for details. -sub reply_handler { - my ($qname, $qclass, $qtype) = @_; - my ($rcode, @ans, @auth, @add, $wait); - - print ("request: $qname/$qtype\n"); - STDOUT->flush(); - - $wait = 0; - $count += 1; - - if ($qname eq "count" ) { - if ($qtype eq "TXT") { - my ($ttl, $rdata) = (0, "$count"); - my $rr = new Net::DNS::RR("$qname $ttl $qclass $qtype $rdata"); - push @ans, $rr; - print ("\tcount: $count\n"); - } - $rcode = "NOERROR"; - } elsif ($qname eq "reset" ) { - $count = 0; - $send_response = 0; - $limit = getlimit(); - $rcode = "NOERROR"; - print ("\tlimit: $limit\n"); - } elsif ($qname eq "direct.example.org" ) { - if ($qtype eq "A") { - my ($ttl, $rdata) = (3600, $localaddr); - my $rr = new Net::DNS::RR("$qname $ttl $qclass $qtype $rdata"); - push @ans, $rr; - } - $rcode = "NOERROR"; - } elsif ($qname eq "indirect1.example.org" || - $qname eq "indirect2.example.org" || - $qname eq "indirect3.example.org" || - $qname eq "indirect4.example.org" || - $qname eq "indirect5.example.org" || - $qname eq "indirect6.example.org" || - $qname eq "indirect7.example.org" || - $qname eq "indirect8.example.org") { - if (! $send_response) { - my $rr = new Net::DNS::RR("$qname 86400 $qclass NS ns1.1.example.org"); - push @auth, $rr; - } elsif ($qtype eq "A") { - my ($ttl, $rdata) = (3600, $localaddr); - my $rr = new Net::DNS::RR("$qname $ttl $qclass $qtype $rdata"); - push @ans, $rr; - } - $rcode = "NOERROR"; - } elsif ($qname =~ /^ns1\.(\d+)\.example\.org$/) { - my $next = $1 + 1; - $wait = 1; - if ($limit == 0 || (! $send_response && $next <= $limit)) { - my $rr = new Net::DNS::RR("$1.example.org 86400 $qclass NS ns1.$next.example.org"); - push @auth, $rr; - } else { - $send_response = 1; - if ($qtype eq "A") { - my ($ttl, $rdata) = (3600, "10.53.0.4"); - my $rr = new Net::DNS::RR("$qname $ttl $qclass $qtype $rdata"); - print("\tresponse: $qname $ttl $qclass $qtype $rdata\n"); - push @ans, $rr; - } - } - $rcode = "NOERROR"; - } elsif ($qname eq "direct.example.net" ) { - if ($qtype eq "A") { - my ($ttl, $rdata) = (3600, $localaddr); - my $rr = new Net::DNS::RR("$qname $ttl $qclass $qtype $rdata"); - push @ans, $rr; - } - $rcode = "NOERROR"; - } elsif( $qname =~ /^ns1\.(\d+)\.example\.net$/ ) { - my $next = ($1 + 1) * 16; - for (my $i = 1; $i < 16; $i++) { - my $s = $next + $i; - my $rr = new Net::DNS::RR("$1.example.net 86400 $qclass NS ns1.$s.example.net"); - push @auth, $rr; - $rr = new Net::DNS::RR("ns1.$s.example.net 86400 $qclass A 10.53.0.7"); - push @add, $rr; - } - $rcode = "NOERROR"; - } else { - $rcode = "NXDOMAIN"; - } - - return ($rcode, \@ans, \@auth, \@add, $wait); -} - -sub handleUDP { - my ($buf, $peer) = @_; - my ($request, $rcode, $ans, $auth, $add, $wait); - - $request = new Net::DNS::Packet(\$buf, 0); - $@ and die $@; - - my ($question) = $request->question; - my $qname = $question->qname; - my $qclass = $question->qclass; - my $qtype = $question->qtype; - - ($rcode, $ans, $auth, $add, $wait) = reply_handler($qname, $qclass, $qtype); - - my $reply = $request->reply(); - - $reply->header->rcode($rcode); - $reply->header->aa(@$ans ? 1 : 0); - $reply->header->id($request->header->id); - $reply->{answer} = $ans if $ans; - $reply->{authority} = $auth if $auth; - $reply->{additional} = $add if $add; - - if ($wait) { - # reply_handler() asked us to delay sending this reply until - # another reply with $wait == 1 is generated or a timeout - # occurs. - if (@delayed_response) { - # A delayed reply is already queued, so we can now send - # both the delayed reply and the current reply. - send_delayed_response(); - return $reply; - } elsif ($no_more_waiting) { - # It was determined before that there is no point in - # waiting for "accompanying" queries. Thus, send the - # current reply immediately. - return $reply; - } else { - # No delayed reply is queued and the client is expected - # to send an "accompanying" query shortly. Do not send - # the current reply right now, just save it for later - # and wait for an "accompanying" query to be received. - @delayed_response = ($reply, $peer); - $timeout = 0.5; - return; - } - } else { - # Send reply immediately. - return $reply; - } -} - -sub send_delayed_response { - my ($reply, $peer) = @delayed_response; - # Truncation to 512 bytes is required for triggering "NS explosion" on - # builds without IPv6 support - $udpsock->send($reply->data(512), 0, $peer); - undef @delayed_response; - undef $timeout; -} - -# Main -my $rin; -my $rout; -for (;;) { - $rin = ''; - vec($rin, fileno($udpsock), 1) = 1; - - select($rout = $rin, undef, undef, $timeout); - - if (vec($rout, fileno($udpsock), 1)) { - my ($buf, $peer, $reply); - $udpsock->recv($buf, 512); - $peer = $udpsock->peername(); - $reply = handleUDP($buf, $peer); - # Truncation to 512 bytes is required for triggering "NS - # explosion" on builds without IPv6 support - $udpsock->send($reply->data(512), 0, $peer) if $reply; - } else { - # An "accompanying" query was expected to come in, but did not. - # Assume the client never sends "accompanying" queries to - # prevent pointlessly waiting for them ever again. - $no_more_waiting = 1; - # Send the delayed reply to the query which caused us to wait. - send_delayed_response(); - } -} diff --git a/bin/tests/system/reclimit/ans2/ans.py b/bin/tests/system/reclimit/ans2/ans.py new file mode 100644 index 00000000000..4d6e9acc2ad --- /dev/null +++ b/bin/tests/system/reclimit/ans2/ans.py @@ -0,0 +1,79 @@ +""" +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. +""" + +from collections.abc import AsyncGenerator + +import dns.rcode + +from isctest.asyncserver import ( + ControllableAsyncDnsServer, + DnsResponseSend, + QueryContext, +) + +from ..reclimit_ans import ( + DirectExampleHandler, + FallbackNxdomainHandler, + IndirectExampleOrgHandler, + LimitControlCommand, + Ns1ExampleOrgHandler, + ReclimitHandler, + ReclimitStateHandler, + a, + is_ns1_example, + ns, +) + + +class Ns1ExampleNetHandler(ReclimitHandler): + def match(self, qctx: QueryContext) -> bool: + return is_ns1_example(qctx.qname, "net") + + async def _get_counted_responses( + self, qctx: QueryContext + ) -> AsyncGenerator[DnsResponseSend, None]: + current_ns_number = int(qctx.qname.labels[1]) + next_ns_block_start = (current_ns_number + 1) * 16 + for offset in range(1, 16): + target_ns_number = next_ns_block_start + offset + qctx.response.authority.append( + ns( + f"{current_ns_number}.example.net.", + f"ns1.{target_ns_number}.example.net.", + ) + ) + qctx.response.additional.append( + a(f"ns1.{target_ns_number}.example.net.", 7) + ) + + yield DnsResponseSend(qctx.response, authoritative=False) + + +def main() -> None: + server = ControllableAsyncDnsServer( + default_aa=True, default_rcode=dns.rcode.NOERROR + ) + server.install_response_handlers( + state_handler := ReclimitStateHandler(indirect_send_response_default=False), + DirectExampleHandler(state_handler, 2), + IndirectExampleOrgHandler(state_handler, 2), + Ns1ExampleOrgHandler(state_handler), + Ns1ExampleNetHandler(state_handler), + FallbackNxdomainHandler(state_handler), + ) + server.install_control_command(LimitControlCommand(state_handler)) + server.run() + + +if __name__ == "__main__": + main() diff --git a/bin/tests/system/reclimit/tests.sh b/bin/tests/system/reclimit/tests.sh index 09bee7a413a..134f9852da6 100644 --- a/bin/tests/system/reclimit/tests.sh +++ b/bin/tests/system/reclimit/tests.sh @@ -76,7 +76,7 @@ echo_i "set max-recursion-depth=12" n=$((n + 1)) echo_i "attempt excessive-depth lookup ($n)" ret=0 -echo "1000" >ans2/ans.limit +set_limit 10.53.0.2 1000 $n set_limit 10.53.0.4 1000 $n dig_with_opts @10.53.0.2 reset >/dev/null || ret=1 dig_with_opts @10.53.0.4 reset >/dev/null || ret=1 @@ -91,7 +91,7 @@ status=$((status + ret)) n=$((n + 1)) echo_i "attempt permissible lookup ($n)" ret=0 -echo "12" >ans2/ans.limit +set_limit 10.53.0.2 12 $n set_limit 10.53.0.4 12 $n ns3_reset dig_with_opts @10.53.0.2 reset >/dev/null || ret=1 @@ -109,7 +109,7 @@ echo_i "set max-recursion-depth=5" n=$((n + 1)) echo_i "attempt excessive-depth lookup ($n)" ret=0 -echo "12" >ans2/ans.limit +set_limit 10.53.0.2 12 $n cp ns3/named2.conf ns3/named.conf ns3_reset dig_with_opts @10.53.0.2 reset >/dev/null || ret=1 @@ -125,7 +125,7 @@ status=$((status + ret)) n=$((n + 1)) echo_i "attempt permissible lookup ($n)" ret=0 -echo "5" >ans2/ans.limit +set_limit 10.53.0.2 5 $n set_limit 10.53.0.4 5 $n ns3_reset dig_with_opts @10.53.0.2 reset >/dev/null || ret=1 @@ -143,7 +143,7 @@ echo_i "set max-recursion-depth=100, max-recursion-queries=50" n=$((n + 1)) echo_i "attempt excessive-queries lookup ($n)" ret=0 -echo "13" >ans2/ans.limit +set_limit 10.53.0.2 13 $n set_limit 10.53.0.4 13 $n cp ns3/named3.conf ns3/named.conf ns3_reset @@ -166,7 +166,7 @@ status=$((status + ret)) n=$((n + 1)) echo_i "attempt permissible lookup ($n)" ret=0 -echo "12" >ans2/ans.limit +set_limit 10.53.0.2 12 $n ns3_reset dig_with_opts @10.53.0.2 reset >/dev/null || ret=1 dig_with_opts @10.53.0.3 indirect6.example.org >dig.out.1.test$n || ret=1 @@ -185,7 +185,7 @@ echo_i "set max-recursion-depth=100, max-recursion-queries=40" n=$((n + 1)) echo_i "attempt excessive-queries lookup ($n)" ret=0 -echo "11" >ans2/ans.limit +set_limit 10.53.0.2 11 $n cp ns3/named4.conf ns3/named.conf ns3_reset dig_with_opts @10.53.0.2 reset >/dev/null || ret=1 @@ -205,7 +205,7 @@ status=$((status + ret)) n=$((n + 1)) echo_i "attempt permissible lookup ($n)" ret=0 -echo "9" >ans2/ans.limit +set_limit 10.53.0.2 9 $n ns3_reset dig_with_opts @10.53.0.2 reset >/dev/null || ret=1 dig_with_opts @10.53.0.3 indirect8.example.org >dig.out.1.test$n || ret=1