Implement TLS wrapper mode.

5 files changed, 106 insertions, 10 deletions

diff --git a/changes/feature_3637-use-tls-wrapper-mode b/changes/feature_3637-use-tls-wrapper-mode
new file mode 100644
index 0000000..668015f
--- /dev/null
+++ b/changes/feature_3637-use-tls-wrapper-mode
@@ -0,0 +1 @@
+  o Use TLS wrapper mode instead of STARTTLS. Closes #3637.
diff --git a/src/leap/mail/smtp/smtprelay.py b/src/leap/mail/smtp/smtprelay.py
index d9bbbf9..fca66c0 100644
--- a/src/leap/mail/smtp/smtprelay.py
+++ b/src/leap/mail/smtp/smtprelay.py
@@ -17,6 +17,20 @@
 
 """
 LEAP SMTP encrypted relay.
+
+The following classes comprise the SMTP relay service:
+
+    * SMTPFactory - A twisted.internet.protocol.ServerFactory that provides
+      the SMTPDelivery protocol.
+    * SMTPDelivery - A twisted.mail.smtp.IMessageDelivery implementation. It
+      knows how to validate sender and receiver of messages and it generates
+      an EncryptedMessage for each recipient.
+    * SSLContextFactory - Contains the relevant ssl information for the
+      connection.
+    * EncryptedMessage - An implementation of twisted.mail.smtp.IMessage that
+      knows how to encrypt/sign itself before sending.
+
+
 """
 
 import re
@@ -173,7 +187,6 @@ class SMTPFactory(ServerFactory):
         @return: The protocol.
         @rtype: SMTPDelivery
         """
-        # If needed, we might use ESMTPDelivery here instead.
         smtpProtocol = smtp.SMTP(SMTPDelivery(self._km, self._config))
         smtpProtocol.factory = self
         return smtpProtocol
@@ -305,7 +318,7 @@ class SMTPDelivery(object):
 # EncryptedMessage
 #
 
-class CtxFactory(ssl.ClientContextFactory):
+class SSLContextFactory(ssl.ClientContextFactory):
     def __init__(self, cert, key):
         self.cert = cert
         self.key = key
@@ -450,6 +463,8 @@ class EncryptedMessage(object):
                                                      self._config[PORT_KEY]))
 
         d = defer.Deferred()
+        # we don't pass an ssl context factory to the ESMTPSenderFactory
+        # because ssl will be handled by reactor.connectSSL() below.
         factory = smtp.ESMTPSenderFactory(
             "",  # username is blank because server does not use auth.
             "",  # password is blank because server does not use auth.
@@ -457,15 +472,15 @@ class EncryptedMessage(object):
             self._user.dest.addrstr,
             StringIO(msg),
             d,
-            contextFactory=CtxFactory(self._config[CERT_KEY],
-                                      self._config[KEY_KEY]),
-            requireAuthentication=False)
+            requireAuthentication=False,
+            requireTransportSecurity=True)
         signal(proto.SMTP_SEND_MESSAGE_START, self._user.dest.addrstr)
-        reactor.connectTCP(
+        reactor.connectSSL(
             self._config[HOST_KEY],
             self._config[PORT_KEY],
-            factory
-        )
+            factory,
+            contextFactory=SSLContextFactory(self._config[CERT_KEY],
+                                             self._config[KEY_KEY]))
         d.addCallback(self.sendSuccess)
         d.addErrback(self.sendError)
         return d
diff --git a/src/leap/mail/smtp/tests/__init__.py b/src/leap/mail/smtp/tests/__init__.py
index 7fed7da..9b54de3 100644
--- a/src/leap/mail/smtp/tests/__init__.py
+++ b/src/leap/mail/smtp/tests/__init__.py
@@ -113,8 +113,8 @@ class TestCaseWithKeyManager(BaseLeapTest):
             'username': address,
             'password': '<password>',
             'encrypted_only': True,
-            'cert': 'blah',
-            'key': 'bleh',
+            'cert': 'src/leap/mail/smtp/tests/cert/server.crt',
+            'key': 'src/leap/mail/smtp/tests/cert/server.key',
         }
 
         class Response(object):
diff --git a/src/leap/mail/smtp/tests/cert/server.crt b/src/leap/mail/smtp/tests/cert/server.crt
new file mode 100644
index 0000000..a27391c
--- /dev/null
+++ b/src/leap/mail/smtp/tests/cert/server.crt
@@ -0,0 +1,29 @@
+-----BEGIN CERTIFICATE-----
+MIIFBjCCAu4CCQCWn3oMoQrDJTANBgkqhkiG9w0BAQUFADBFMQswCQYDVQQGEwJV
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+adOT0FpU64RPNrQz5NF1bSIjqrHSaRVacf8yr7qqxNnpMsrtkDJzsMBz
+-----END CERTIFICATE-----
diff --git a/src/leap/mail/smtp/tests/cert/server.key b/src/leap/mail/smtp/tests/cert/server.key
new file mode 100644
index 0000000..197a449
--- /dev/null
+++ b/src/leap/mail/smtp/tests/cert/server.key
@@ -0,0 +1,51 @@
+-----BEGIN RSA PRIVATE KEY-----
+MIIJKQIBAAKCAgEA97FO8S8btxKZl0AREe31MHXVxKivnhj8Xs2Zgx1I4k2LhjST
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+-----END RSA PRIVATE KEY-----