tests: add dummy SMTP daemon for SSL tests

Currently it only supports SMTP over SSL since SMTPS should be simpler than
handling StartTLS.

Since we don't need asynchronous server for our tests, it does TLS handshake
in blocking way. But asyncore is required by Python smtpd module.

tests/dummysmtpd.py

@@ -0,0 +1,81 b''
+#!/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
+
+from mercurial import (
+    cmdutil,
+)
+
+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):
+        log('%s from=%s to=%s\n' % (peer[0], mailfrom, ', '.join(rcpttos)))
+
+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
+        try:
+            # wrap_socket() would block, but we don't care
+            conn = ssl.wrap_socket(conn, server_side=True,
+                                   certfile=self._certfile,
+                                   ssl_version=ssl.PROTOCOL_TLSv1)
+        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 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)
+
+    cmdutil.service(vars(opts), initfn=init, runfn=run,
+                    runargs=[sys.executable, __file__] + sys.argv[1:])
+
+if __name__ == '__main__':
+    main()