[feat] postfix lookup against couchdb for client smtp fingerprint

- Resolves: #4285

6 files changed, 151 insertions, 0 deletions

diff --git a/changes/next-changelog.txt b/changes/next-changelog.txt
index fbee095..641e26c 100644
--- a/changes/next-changelog.txt
+++ b/changes/next-changelog.txt
@@ -10,6 +10,7 @@ I've added a new category `Misc` so we can track doc/style/packaging stuff.
 
 Features
 ~~~~~~~~
+- `#4285 <https://leap.se/code/issues/4285>`_: Add postfix lookup against couchdb for client smtp fingerprint
 - `#5959 <https://leap.se/code/issues/5959>`_: Make alias resolver to return *uuid@deliver.local*
 - `#1234 <https://leap.se/code/issues/1234>`_: Description of the new feature corresponding with issue #1234.
 - New feature without related issue number.
diff --git a/doc/DESIGN.md b/doc/DESIGN.md
index e33c6ae..dbfbc99 100644
--- a/doc/DESIGN.md
+++ b/doc/DESIGN.md
@@ -145,6 +145,19 @@ virtual transport instead, we should append the domain (eg
 123456@example.org). see
 http://www.postfix.org/ADDRESS_REWRITING_README.html#resolve
 
+#### fingerprint_resolver
+
+postfix config:
+
+```
+virtual_alias_map tcp:localhost:2424
+```
+
+postfix sends "get 12:34:56:78:90:ab:cd:ef:12:34:56:78:90:ab:cd:ef:12:34:56:78"
+providing an smtp fingerprint and fingerprint_resolver returns "200 2016-01-19",
+where 2016-01-19 is the expiration date of the given fingerprint. If the
+fingerprint does not exists or is expired it will return "500 NOT FOUND SRY".
+
 #### Return values
 
 The return codes and content of the tcp maps are:
diff --git a/pkg/mx.conf.sample b/pkg/mx.conf.sample
index c9ad0f8..a649b73 100644
--- a/pkg/mx.conf.sample
+++ b/pkg/mx.conf.sample
@@ -14,6 +14,9 @@ port=4242
 [check recipient]
 port=2244
 
+[fingerprint map]
+port=2424
+
 [bounce]
 from=<address for the From: of the bounce email without domain>
 subject=Delivery failure
\ No newline at end of file
diff --git a/pkg/mx.tac b/pkg/mx.tac
index 4ae08f2..42d40a8 100755
--- a/pkg/mx.tac
+++ b/pkg/mx.tac
@@ -24,6 +24,7 @@ from leap.mx import couchdbhelper
 from leap.mx.mail_receiver import MailReceiver
 from leap.mx.alias_resolver import AliasResolverFactory
 from leap.mx.check_recipient_access import CheckRecipientAccessFactory
+from leap.mx.fingerprint_resolver import FingerprintResolverFactory
 
 try:
     from twisted.application import service, internet
@@ -57,6 +58,7 @@ except ConfigParser.NoSectionError:
 
 alias_port = config.getint("alias map", "port")
 check_recipient_port = config.getint("check recipient", "port")
+fingerprint_port = config.getint("fingerprint map", "port")
 
 cdb = couchdbhelper.ConnectedCouchDB(server,
                                      port=port,
@@ -79,6 +81,12 @@ check_recipient = internet.TCPServer(
     interface="localhost")
 check_recipient.setServiceParent(application)
 
+# Fingerprint map
+fingerprint_map = internet.TCPServer(
+    fingerprint_port, FingerprintResolverFactory(couchdb=cdb),
+    interface="localhost")
+fingerprint_map.setServiceParent(application)
+
 # Mail receiver
 directories = []
 for section in config.sections():
diff --git a/src/leap/mx/couchdbhelper.py b/src/leap/mx/couchdbhelper.py
index 115ecbe..de133d5 100644
--- a/src/leap/mx/couchdbhelper.py
+++ b/src/leap/mx/couchdbhelper.py
@@ -138,6 +138,34 @@ class ConnectedCouchDB(client.CouchDB):
         d.addCallbacks(_get_pubkey_cbk, log.err)
         return d
 
+    def getCertExpiry(self, fingerprint):
+        """
+        Query couch and return a deferred that will fire with the expiration
+        date for the cert with the given fingerprint.
+
+        :param fingerprint: The cert fingerprint
+        :type fingerprint: str
+
+        :return: A deferred that will fire with the cert expiration date as a
+                 str.
+        :rtype: Deferred
+        """
+        d = self.openView(docId="Identity",
+                          viewId="cert_expiry_by_fingerprint/",
+                          key=fingerprint,
+                          reduce=False,
+                          include_docs=True)
+
+        def _get_cert_expiry_cbk(result):
+            try:
+                expiry = result["rows"][0]["value"]
+            except (KeyError, IndexError):
+                expiry = None
+            return expiry
+
+        d.addCallback(_get_cert_expiry_cbk)
+        return d
+
     def put_doc(self, uuid, doc):
         """
         Update a document.
diff --git a/src/leap/mx/fingerprint_resolver.py b/src/leap/mx/fingerprint_resolver.py
new file mode 100644
index 0000000..0a0850d
--- /dev/null
+++ b/src/leap/mx/fingerprint_resolver.py
@@ -0,0 +1,98 @@
+#!/usr/bin/env python
+# -*- encoding: utf-8 -*-
+# fingerprint_resolver.py
+# Copyright (C) 2015 LEAP
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+"""
+Classes for resolve expiration date of certs.
+
+Test this with postmap -v -q "fingerprint" tcp:localhost:2424
+"""
+
+
+from datetime import datetime
+from twisted.internet.protocol import ServerFactory
+from twisted.protocols import postfix
+from twisted.python import log
+
+from leap.mx.tcp_map import TCP_MAP_CODE_SUCCESS
+from leap.mx.tcp_map import TCP_MAP_CODE_PERMANENT_FAILURE
+
+
+class LEAPPostfixTCPMapFingerprintServer(postfix.PostfixTCPMapServer):
+    """
+    A postfix tcp map fingerprint resolver server.
+    """
+
+    def _cbGot(self, res):
+        """
+        Return a code and message depending on the result of the factory's
+        get().
+
+        :param res: The fingerprint and expiration date of the cert
+        :type res: (str, str)
+        """
+        fingerprint, expiry = (None, None)
+        if res is not None:
+            fingerprint, expiry = res
+
+        if expiry is None:
+            code = TCP_MAP_CODE_PERMANENT_FAILURE
+            msg = "NOT FOUND SRY"
+        elif expiry < datetime.utcnow().strftime("%Y-%m-%d"):
+            code = TCP_MAP_CODE_PERMANENT_FAILURE
+            msg = "EXPIRED CERT"
+        else:
+            # properly encode expiry, otherwise twisted complains when replying
+            if isinstance(expiry, unicode):
+                expiry = expiry.encode("utf8")
+            code = TCP_MAP_CODE_SUCCESS
+            msg = fingerprint + " " + expiry
+
+        self.sendCode(code, postfix.quote(msg))
+
+
+class FingerprintResolverFactory(ServerFactory, object):
+    """
+    A factory for postfix tcp map fingerprint resolver servers.
+    """
+
+    protocol = LEAPPostfixTCPMapFingerprintServer
+
+    def __init__(self, couchdb):
+        """
+        Initialize the factory.
+
+        :param couchdb: A CouchDB client.
+        :type couchdb: leap.mx.couchdbhelper.ConnectedCouchDB
+        """
+        self._cdb = couchdb
+
+    def get(self, fingerprint):
+        """
+        Look up the cert expiration date based on fingerprint.
+
+        :param fingerprint: The cert fingerprint.
+        :type fingerprint: str
+
+        :return: A deferred that will be fired with the expiration date.
+        :rtype: Deferred
+        """
+        log.msg("look up: %s" % (fingerprint,))
+        d = self._cdb.getCertExpiry(fingerprint.lower())
+        d.addCallback(lambda expiry: (fingerprint, expiry))
+        d.addErrback(log.err)
+        return d