tests/dummysmtpd.py

tests: add a module that can perform the equivalent of `SIGKILL` on any OS

I started with this being Windows specific, but let's push all of the decision
making into this function so that it can just be called by the tests.  The
tradeoff is that this is very specific to sending `SIGKILL`- since
`signal.SIGKILL` doesn't exist on Windows, the desired signal can't be passed
from the caller.  Maybe there's a way, but let's wait until there's a need.

We don't use `killdaemons.py` unconditionally because it starts with a more
graceful `SIGTERM` on posix.

#!/usr/bin/env python

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


import optparse
import os
import socket
import ssl
import sys

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


if os.environ.get('HGIPV6', '0') == '1':
    family = socket.AF_INET6
else:
    family = socket.AF_INET


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


def mocksmtpserversession(conn, addr):
    conn.send(b'220 smtp.example.com ESMTP\r\n')

    try:
        # Newer versions of OpenSSL raise on EOF
        line = conn.recv(1024)
    except ssl.SSLError:
        log('no hello: EOF\n')
        return

    if not line.lower().startswith(b'ehlo '):
        # Older versions of OpenSSl don't raise
        log('no hello: %s\n' % line)
        return

    conn.send(b'250 Hello\r\n')

    line = conn.recv(1024)
    if not line.lower().startswith(b'mail from:'):
        log('no mail from: %s\n' % line)
        return
    mailfrom = line[10:].decode().rstrip()
    if mailfrom.startswith('<') and mailfrom.endswith('>'):
        mailfrom = mailfrom[1:-1]

    conn.send(b'250 Ok\r\n')

    rcpttos = []
    while True:
        line = conn.recv(1024)
        if not line.lower().startswith(b'rcpt to:'):
            break
        rcptto = line[8:].decode().rstrip()
        if rcptto.startswith('<') and rcptto.endswith('>'):
            rcptto = rcptto[1:-1]
        rcpttos.append(rcptto)

        conn.send(b'250 Ok\r\n')

    if not line.lower().strip() == b'data':
        log('no rcpt to or data: %s' % line)

    conn.send(b'354 Go ahead\r\n')

    data = b''
    while True:
        line = conn.recv(1024)
        if not line:
            log('connection closed before end of data')
            break
        data += line
        if data.endswith(b'\r\n.\r\n'):
            data = data[:-5]
            break

    conn.send(b'250 Ok\r\n')

    log(
        '%s from=%s to=%s\n%s\n'
        % (addr[0], mailfrom, ', '.join(rcpttos), data.decode())
    )


def run(host, port, certificate):
    ui = uimod.ui.load()
    with socket.socket(family, socket.SOCK_STREAM) as s:
        s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
        s.bind((host, port))
        # log('listening at %s:%d\n' % (host, port))
        s.listen(1)
        try:
            while True:
                conn, addr = s.accept()
                if certificate:
                    try:
                        conn = sslutil.wrapserversocket(
                            conn, ui, certfile=certificate
                        )
                    except ssl.SSLError as e:
                        log('%s ssl error: %s\n' % (addr[0], e))
                        conn.close()
                        continue
                log("connection from %s:%s\n" % addr)
                mocksmtpserversession(conn, addr)
                conn.close()
        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')
    op.add_option('--logfile', metavar='FILE')

    opts, args = op.parse_args()
    if (opts.tls == 'smtps') != bool(opts.certificate):
        op.error('--certificate must be specified with --tls=smtps')

    server.runservice(
        bytesvars(opts),
        runfn=lambda: run(opts.address, opts.port, opts.certificate),
        runargs=[pycompat.sysexecutable, pycompat.fsencode(__file__)]
        + pycompat.sysargv[1:],
        logfile=opts.logfile,
    )


if __name__ == '__main__':
    main()