Merge lp:~jcsackett/launchpad/email-authentication-type-error into lp:launchpad

[j.c.sackett]

Updates authenticateEmail to gracefully handle TypeErrors from badly formed email addresses.

Summary
=======
authenticateEmail crashes on bad email address (e.g. ones that are not pure
unicode but also not US-ASCII). While we can't process them, we shouldn't
crash either.

The better approach is to simply proceed without having been able to
authenticate, and set an anauthenticated principal as we do with unknown
emails.

Implementation
==============
The call in `authenticateEmail` to `getPrincipalByLogin` is now in a
try/except block, which handles `TypeError` by setting principal to None. A
principal of None is a case which the rest of the code already handles
gracefully.

Tests
=====
bin/test -vvct test_badly_formed_email

QA
==
Using testemail.py (Curtis Hovey's script), contrive an email that has the right properties, and ensure it doesn't cause an OOPS.

LoC
===
I have approx 400 LoC credit.

Lint
====

Checking for conflicts and issues in changed files.

Linting changed files:
  lib/lp/services/mail/incoming.py
  lib/lp/services/mail/tests/test_incoming.py

[Curtis Hovey (sinzui)]

Thank you.

I have a script (testemail.py) I use to send "volleys" of emails at Lp. We might be able to use to to contrive the example address in the bug.

review: Approve (code)

=== modified file 'lib/lp/services/mail/incoming.py'
--- lib/lp/services/mail/incoming.py	2012-09-20 05:59:58 +0000
+++ lib/lp/services/mail/incoming.py	2012-10-24 20:44:20 +0000
@@ -258,7 +258,11 @@
     principal, dkim_trusted_address = _getPrincipalByDkim(mail)
     if dkim_trusted_address is None:
         from_addr = parseaddr(mail['From'])[1]
-        principal = authutil.getPrincipalByLogin(from_addr)
+        try:
+            principal = authutil.getPrincipalByLogin(from_addr)
+        except TypeError:
+            # The email isn't valid, so don't authenticate
+            principal = None
 
     if principal is None:
         setupInteraction(authutil.unauthenticatedPrincipal())

=== modified file 'lib/lp/services/mail/tests/test_incoming.py'
--- lib/lp/services/mail/tests/test_incoming.py	2012-09-20 05:44:34 +0000
+++ lib/lp/services/mail/tests/test_incoming.py	2012-10-24 20:44:20 +0000
@@ -126,6 +126,12 @@
         mail = self.factory.makeSignedMessage(email_address=unknown)
         self.assertThat(authenticateEmail(mail), Is(None))
 
+    def test_badly_formed_email(self):
+        # A badly formed email address returns no principal.
+        bad = '\[e-mail]'
+        mail = self.factory.makeSignedMessage(email_address=bad)
+        self.assertThat(authenticateEmail(mail), Is(None))
+
 
 class TestExtractAddresses(TestCaseWithFactory):