Mercurial > hg
diff tests/sshprotoext.py @ 35930:83d67257ba90
tests: add low-level SSH protocol tests
We don't really have good low-level tests for the behavior of the SSH
wire protocol. This commit attempts to establish some.
The added tests consist of a mixture of starting a server
with `hg serve --stdio` and sending bytes to it and using
`hg debugpeer` to go through the official client code. Having
insight into what raw bytes are exchanged as well as what the peer
does is useful.
We also introduce a test extension for modifying the behavior of
the SSH server and peer. For example, we change the server to
not recognize the "hello" command, simulating behavior of <0.9.1
servers.
These tests are generally useful to have. But the impetus for creating
them now is they will be needed for verifying behavior of old clients
and servers when a new SSH protocol is introduced.
Differential Revision: https://phab.mercurial-scm.org/D2026
# no-check-commit because of serve_forever()
author | Gregory Szorc <gregory.szorc@gmail.com> |
---|---|
date | Sun, 04 Feb 2018 14:02:41 -0800 |
parents | |
children | a9cffd14aa04 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/tests/sshprotoext.py Sun Feb 04 14:02:41 2018 -0800 @@ -0,0 +1,108 @@ +# sshprotoext.py - Extension to test behavior of SSH protocol +# +# Copyright 2018 Gregory Szorc <gregory.szorc@gmail.com> +# +# This software may be used and distributed according to the terms of the +# GNU General Public License version 2 or any later version. + +# This extension replaces the SSH server started via `hg serve --stdio`. +# The server behaves differently depending on environment variables. + +from __future__ import absolute_import + +from mercurial import ( + error, + registrar, + sshpeer, + wireproto, + wireprotoserver, +) + +configtable = {} +configitem = registrar.configitem(configtable) + +configitem('sshpeer', 'mode', default=None) +configitem('sshpeer', 'handshake-mode', default=None) + +class bannerserver(wireprotoserver.sshserver): + """Server that sends a banner to stdout.""" + def serve_forever(self): + for i in range(10): + self._fout.write(b'banner: line %d\n' % i) + + super(bannerserver, self).serve_forever() + +class prehelloserver(wireprotoserver.sshserver): + """Tests behavior when connecting to <0.9.1 servers. + + The ``hello`` wire protocol command was introduced in Mercurial + 0.9.1. Modern clients send the ``hello`` command when connecting + to SSH servers. This mock server tests behavior of the handshake + when ``hello`` is not supported. + """ + def serve_forever(self): + l = self._fin.readline() + assert l == b'hello\n' + # Respond to unknown commands with an empty reply. + self._sendresponse(b'') + l = self._fin.readline() + assert l == b'between\n' + rsp = wireproto.dispatch(self._repo, self, b'between') + self._handlers[rsp.__class__](self, rsp) + + super(prehelloserver, self).serve_forever() + +class extrahandshakecommandspeer(sshpeer.sshpeer): + """An ssh peer that sends extra commands as part of initial handshake.""" + # There isn't a good hook point. So we wrap _callstream() and inject + # logic when the peer says "hello". + def _callstream(self, cmd, **args): + if cmd != b'hello': + return super(extrahandshakecommandspeer, self)._callstream(cmd, + **args) + + mode = self._ui.config(b'sshpeer', b'handshake-mode') + if mode == b'pre-no-args': + self._callstream(b'no-args') + return super(extrahandshakecommandspeer, self)._callstream( + cmd, **args) + elif mode == b'pre-multiple-no-args': + self._callstream(b'unknown1') + self._callstream(b'unknown2') + self._callstream(b'unknown3') + return super(extrahandshakecommandspeer, self)._callstream( + cmd, **args) + else: + raise error.ProgrammingError(b'unknown HANDSHAKECOMMANDMODE: %s' % + mode) + +def registercommands(): + def dummycommand(repo, proto): + raise error.ProgrammingError('this should never be called') + + wireproto.wireprotocommand(b'no-args', b'')(dummycommand) + wireproto.wireprotocommand(b'unknown1', b'')(dummycommand) + wireproto.wireprotocommand(b'unknown2', b'')(dummycommand) + wireproto.wireprotocommand(b'unknown3', b'')(dummycommand) + +def extsetup(ui): + # It's easier for tests to define the server behavior via environment + # variables than config options. This is because `hg serve --stdio` + # has to be invoked with a certain form for security reasons and + # `dummyssh` can't just add `--config` flags to the command line. + servermode = ui.environ.get(b'SSHSERVERMODE') + + if servermode == b'banner': + wireprotoserver.sshserver = bannerserver + elif servermode == b'no-hello': + wireprotoserver.sshserver = prehelloserver + elif servermode: + raise error.ProgrammingError(b'unknown server mode: %s' % servermode) + + peermode = ui.config(b'sshpeer', b'mode') + + if peermode == b'extra-handshake-commands': + sshpeer.sshpeer = extrahandshakecommandspeer + registercommands() + elif peermode: + raise error.ProgrammingError(b'unknown peer mode: %s' % peermode)