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chg: test: Use isctest.asyncserver in the "nsupdate" test
Reimplement the custom server written in Perl in Python using the AsyncDnsServer class. Merge branch 'stepan/nsupdate-asyncserver' into 'main' See merge request isc-projects/bind9!10915
This commit is contained in:
Štěpán Balážik
commit
09ad0ded75
3 changed files with 90 additions and 105 deletions
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@ -414,6 +414,68 @@ class ConnectionHandler(abc.ABC):
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raise NotImplementedError
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def block_reading(peer: Peer, writer_not_the_reader: asyncio.StreamWriter) -> None:
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"""
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Block reads for the reader associated with the provided writer.
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Yes, pass the writer, not the reader. See the comments below for details.
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"""
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try:
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# Python >= 3.7
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loop = asyncio.get_running_loop()
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except AttributeError:
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# Python < 3.7
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loop = asyncio.get_event_loop()
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logging.info("Blocking reads from %s", peer)
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# This is Michał's submission for the Ugliest Hack of the Year contest.
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# (The alternative was implementing an asyncio transport from scratch.)
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#
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# In order to prevent the client socket from being read from, simply
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# not calling `reader.read()` is not enough, because asyncio buffers
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# incoming data itself on the transport level. However, `StreamReader`
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# does not expose the underlying transport as a property. Therefore,
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# cheat by extracting it from `StreamWriter` as it is the same
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# bidirectional transport as for the read side (a `Transport`, which is
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# a subclass of both `ReadTransport` and `WriteTransport`) and call
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# `ReadTransport.pause_reading()` to remove the underlying socket from
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# the set of descriptors monitored by the selector, thereby preventing
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# any reads from happening on the client socket. However...
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loop.call_soon(writer_not_the_reader.transport.pause_reading) # type: ignore
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# ...due to `AsyncDnsServer._handle_tcp()` being a coroutine, by the
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# time it gets executed, asyncio transport code will already have added
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# the client socket to the set of descriptors monitored by the
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# selector. Therefore, if the client starts sending data immediately,
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# a read from the socket will have already been scheduled by the time
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# this handler gets executed. There is no way to prevent that from
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# happening, so work around it by abusing the fact that the transport
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# at hand is specifically an instance of `_SelectorSocketTransport`
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# (from asyncio.selector_events) and set the size of its read buffer to
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# just a single byte. This does give asyncio enough time to read that
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# single byte from the client socket's buffer before that socket is
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# removed from the set of monitored descriptors, but prevents the
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# one-off read from emptying the client socket buffer _entirely_, which
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# is enough to trigger sending an RST segment when the connection is
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# closed shortly afterwards.
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writer_not_the_reader.transport.max_size = 1 # type: ignore
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@dataclass
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class IgnoreAllConnections(ConnectionHandler):
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"""
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A connection handler that makes the server not read anything from the
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client socket, effectively ignoring all incoming connections.
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"""
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async def handle(
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self, reader: asyncio.StreamReader, writer: asyncio.StreamWriter, peer: Peer
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) -> None:
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block_reading(peer, writer)
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@dataclass
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class ConnectionReset(ConnectionHandler):
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"""
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@ -435,46 +497,7 @@ class ConnectionReset(ConnectionHandler):
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async def handle(
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self, reader: asyncio.StreamReader, writer: asyncio.StreamWriter, peer: Peer
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) -> None:
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try:
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# Python >= 3.7
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loop = asyncio.get_running_loop()
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except AttributeError:
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# Python < 3.7
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loop = asyncio.get_event_loop()
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logging.info("Blocking reads from %s", peer)
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# This is Michał's submission for the Ugliest Hack of the Year contest.
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# (The alternative was implementing an asyncio transport from scratch.)
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#
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# In order to prevent the client socket from being read from, simply
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# not calling `reader.read()` is not enough, because asyncio buffers
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# incoming data itself on the transport level. However, `StreamReader`
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# does not expose the underlying transport as a property. Therefore,
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# cheat by extracting it from `StreamWriter` as it is the same
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# bidirectional transport as for the read side (a `Transport`, which is
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# a subclass of both `ReadTransport` and `WriteTransport`) and call
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# `ReadTransport.pause_reading()` to remove the underlying socket from
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# the set of descriptors monitored by the selector, thereby preventing
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# any reads from happening on the client socket. However...
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loop.call_soon(writer.transport.pause_reading) # type: ignore
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# ...due to `AsyncDnsServer._handle_tcp()` being a coroutine, by the
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# time it gets executed, asyncio transport code will already have added
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# the client socket to the set of descriptors monitored by the
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# selector. Therefore, if the client starts sending data immediately,
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# a read from the socket will have already been scheduled by the time
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# this handler gets executed. There is no way to prevent that from
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# happening, so work around it by abusing the fact that the transport
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# at hand is specifically an instance of `_SelectorSocketTransport`
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# (from asyncio.selector_events) and set the size of its read buffer to
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# just a single byte. This does give asyncio enough time to read that
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# single byte from the client socket's buffer before that socket is
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# removed from the set of monitored descriptors, but prevents the
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# one-off read from emptying the client socket buffer _entirely_, which
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# is enough to trigger sending an RST segment when the connection is
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# closed shortly afterwards.
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writer.transport.max_size = 1 # type: ignore
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block_reading(peer, writer)
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if self.delay > 0:
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logging.info(
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@ -1,65 +0,0 @@
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#!/usr/bin/perl
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# Copyright (C) Internet Systems Consortium, Inc. ("ISC")
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#
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# SPDX-License-Identifier: MPL-2.0
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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 https://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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use IO::Socket;
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use IO::File;
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use strict;
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# Ignore SIGPIPE so we won't fail if peer closes a TCP socket early
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local $SIG{PIPE} = 'IGNORE';
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# Flush logged output after every line
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local $| = 1;
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my $server_addr = "10.53.0.4";
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if (@ARGV > 0) {
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$server_addr = @ARGV[0];
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}
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my $localport = int($ENV{'PORT'});
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if (!$localport) { $localport = 5300; }
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my $udpsock = IO::Socket::INET->new(LocalAddr => "$server_addr",
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LocalPort => $localport, Proto => "udp", Reuse => 1) or die "$!";
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my $tcpsock = IO::Socket::INET->new(LocalAddr => "$server_addr",
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LocalPort => $localport, Proto => "tcp", Listen => 5, Reuse => 1) or die "$!";
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print "listening on $server_addr:$localport.\n";
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my $pidf = new IO::File "ans.pid", "w" or die "cannot open pid file: $!";
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print $pidf "$$\n" or die "cannot write pid file: $!";
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$pidf->close or die "cannot close pid file: $!";;
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sub rmpid { unlink "ans.pid"; exit 1; };
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$SIG{INT} = \&rmpid;
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$SIG{TERM} = \&rmpid;
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# Main
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for (;;) {
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my $rin;
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my $rout;
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$rin = '';
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vec($rin, fileno($udpsock), 1) = 1;
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vec($rin, fileno($tcpsock), 1) = 1;
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select($rout = $rin, undef, undef, undef);
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if (vec($rout, fileno($udpsock), 1)) {
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printf "UDP request\n";
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my $buf;
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$udpsock->recv($buf, 512);
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} elsif (vec($rout, fileno($tcpsock), 1)) {
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printf "TCP request\n";
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}
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}
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27
bin/tests/system/nsupdate/ans4/ans.py
Normal file
27
bin/tests/system/nsupdate/ans4/ans.py
Normal file
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@ -0,0 +1,27 @@
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# Copyright (C) Internet Systems Consortium, Inc. ("ISC")
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#
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# SPDX-License-Identifier: MPL-2.0
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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 https://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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from isctest.asyncserver import (
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AsyncDnsServer,
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IgnoreAllConnections,
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IgnoreAllQueries,
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)
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def main() -> None:
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server = AsyncDnsServer()
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server.install_connection_handler(IgnoreAllConnections())
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server.install_response_handler(IgnoreAllQueries())
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server.run()
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if __name__ == "__main__":
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main()
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