view tests/dummysmtpd.py @ 49000:dd6b67d5c256 stable

rust: fix unsound `OwningDirstateMap`

As per the previous patch, `OwningDirstateMap` is unsound. Self-referential
structs are difficult to implement correctly in Rust since the compiler is
free to move structs around as much as it wants to. They are also very rarely
needed in practice, so the state-of-the-art on how they should be done within
the Rust rules is still a bit new.

The crate `ouroboros` is an attempt at providing a safe way (in the Rust sense)
of declaring self-referential structs. It is getting a lot attention and was
improved very quickly when soundness issues were found in the past: rather than
relying on our own (limited) review circle, we might as well use the de-facto
common crate to fix this problem. This will give us a much better chance of
finding issues should any new ones be discovered as well as the benefit of
fewer `unsafe` APIs of our own.

I was starting to think about how I would present a safe API to the old struct
but soon realized that the callback-based approach was already done in
`ouroboros`, along with a lot more care towards refusing incorrect structs.

In short: we don't return a mutable reference to the `DirstateMap` anymore, we
expect users of its API to pass a `FnOnce` that takes the map as an argument.
This allows our `OwningDirstateMap` to control the input and output lifetimes
of the code that modifies it to prevent such issues.

Changing to `ouroboros` meant changing every API with it, but it is relatively
low churn in the end. It correctly identified the example buggy modification of
`copy_map_insert` outlined in the previous patch as violating the borrow rules.

Differential Revision: https://phab.mercurial-scm.org/D12429

#!/usr/bin/env python

"""dummy SMTP server for use in tests"""

from __future__ import absolute_import

import asyncore
import optparse
import smtpd
import ssl
import sys
import traceback

from mercurial import (
    pycompat,
    server,
    sslutil,
    ui as uimod,
)


def log(msg):
    sys.stdout.write(msg)
    sys.stdout.flush()


class dummysmtpserver(smtpd.SMTPServer):
    def __init__(self, localaddr):
        smtpd.SMTPServer.__init__(self, localaddr, remoteaddr=None)

    def process_message(self, peer, mailfrom, rcpttos, data, **kwargs):
        log('%s from=%s to=%s\n' % (peer[0], mailfrom, ', '.join(rcpttos)))

    def handle_error(self):
        # On Windows, a bad SSL connection sometimes generates a WSAECONNRESET.
        # The default handler will shutdown this server, and then both the
        # current connection and subsequent ones fail on the client side with
        # "No connection could be made because the target machine actively
        # refused it".  If we eat the error, then the client properly aborts in
        # the expected way, and the server is available for subsequent requests.
        traceback.print_exc()


class dummysmtpsecureserver(dummysmtpserver):
    def __init__(self, localaddr, certfile):
        dummysmtpserver.__init__(self, localaddr)
        self._certfile = certfile

    def handle_accept(self):
        pair = self.accept()
        if not pair:
            return
        conn, addr = pair
        ui = uimod.ui.load()
        try:
            # wrap_socket() would block, but we don't care
            conn = sslutil.wrapserversocket(conn, ui, certfile=self._certfile)
        except ssl.SSLError:
            log('%s ssl error\n' % addr[0])
            conn.close()
            return
        smtpd.SMTPChannel(self, conn, addr)


def run():
    try:
        asyncore.loop()
    except KeyboardInterrupt:
        pass


def _encodestrsonly(v):
    if isinstance(v, type(u'')):
        return v.encode('ascii')
    return v


def bytesvars(obj):
    unidict = vars(obj)
    bd = {k.encode('ascii'): _encodestrsonly(v) for k, v in unidict.items()}
    if bd[b'daemon_postexec'] is not None:
        bd[b'daemon_postexec'] = [
            _encodestrsonly(v) for v in bd[b'daemon_postexec']
        ]
    return bd


def main():
    op = optparse.OptionParser()
    op.add_option('-d', '--daemon', action='store_true')
    op.add_option('--daemon-postexec', action='append')
    op.add_option('-p', '--port', type=int, default=8025)
    op.add_option('-a', '--address', default='localhost')
    op.add_option('--pid-file', metavar='FILE')
    op.add_option('--tls', choices=['none', 'smtps'], default='none')
    op.add_option('--certificate', metavar='FILE')

    opts, args = op.parse_args()
    if opts.tls == 'smtps' and not opts.certificate:
        op.error('--certificate must be specified')

    addr = (opts.address, opts.port)

    def init():
        if opts.tls == 'none':
            dummysmtpserver(addr)
        else:
            dummysmtpsecureserver(addr, opts.certificate)
        log('listening at %s:%d\n' % addr)

    server.runservice(
        bytesvars(opts),
        initfn=init,
        runfn=run,
        runargs=[pycompat.sysexecutable, pycompat.fsencode(__file__)]
        + pycompat.sysargv[1:],
    )


if __name__ == '__main__':
    main()