bpo-28879: add Date header to send_message as per RFC5322

lafe3402 · lafe3402 · commit 6d079491e044 · 2018-01-30T19:47:27.000-05:00
diff --git a/Doc/library/smtplib.rst b/Doc/library/smtplib.rst
@@ -496,12 +496,14 @@ An :class:`SMTP` instance has the following methods:
    specified in :rfc:`5322`\: *from_addr* is set to the :mailheader:`Sender`
    field if it is present, and otherwise to the :mailheader:`From` field.
    *to_addrs* combines the values (if any) of the :mailheader:`To`,
-   :mailheader:`Cc`, and :mailheader:`Bcc` fields from *msg*.  If exactly one
-   set of :mailheader:`Resent-*` headers appear in the message, the regular
-   headers are ignored and the :mailheader:`Resent-*` headers are used instead.
-   If the message contains more than one set of :mailheader:`Resent-*` headers,
-   a :exc:`ValueError` is raised, since there is no way to unambiguously detect
-   the most recent set of :mailheader:`Resent-` headers.
+   :mailheader:`Cc`, and :mailheader:`Bcc` fields from *msg*.  If there's no
+   *Date* header inside the message, ``send_message`` will add one to the data.
+   If exactly one set of :mailheader:`Resent-*` headers appear in the message,
+   the regular headers are ignored and the :mailheader:`Resent-*` headers are
+   used instead.  If the message contains more than one set of
+   :mailheader:`Resent-*` headers, a :exc:`ValueError` is raised, since there
+   is no way to unambiguously detect the most recent set of
+   :mailheader:`Resent-` headers.
 
    ``send_message`` serializes *msg* using
    :class:`~email.generator.BytesGenerator` with ``\r\n`` as the *linesep*, and
diff --git a/Lib/smtplib.py b/Lib/smtplib.py
@@ -928,6 +928,10 @@ def send_message(self, msg, from_addr=None, to_addrs=None,
             header_prefix = 'Resent-'
         else:
             raise ValueError("message has more than one 'Resent-' header block")
+
+        # RFC 5322 section 3.6, 4th Paragraph
+        if msg.get('Date', None) is None:
+            msg['Date'] = email.utils.formatdate()
         if from_addr is None:
             # Prefer the sender field per RFC 2822:3.6.2.
             from_addr = (msg[header_prefix + 'Sender']
diff --git a/Lib/test/test_smtplib.py b/Lib/test/test_smtplib.py
@@ -20,6 +20,7 @@
 import unittest
 from test import support, mock_socket
 from test.support import HOST, HOSTv4, HOSTv6
+from unittest.mock import patch
 
 
 if sys.platform == 'darwin':
@@ -558,6 +559,38 @@ def testSendMessageMultipleResentRaises(self):
             smtp.send_message(m)
         smtp.close()
 
+    @patch('email.utils.formatdate')
+    def testSendMessageAddDateIfMissing(self, mocked_date_obj):
+        current_date = 'Thu, 1 Jan 1970 17:42:00 +0000'
+
+        mocked_date_obj.return_value = current_date
+        m = email.mime.text.MIMEText('A test message')
+        m['From'] = 'foo@bar.com'
+        m['To'] = 'John'
+        m['CC'] = 'Sally, Fred'
+        m['Bcc'] = 'John Root <root@localhost>, "Dinsdale" <warped@silly.walks.com>'
+        smtp = smtplib.SMTP(HOST, self.port, local_hostname='localhost', timeout=3)
+        smtp.send_message(m)
+        # XXX (see comment in testSend)
+        time.sleep(0.01)
+        smtp.quit()
+
+        self.client_evt.set()
+        self.serv_evt.wait()
+        self.output.flush()
+        # The Resent-Bcc headers are deleted before serialization.
+        del m['Bcc']
+        del m['Resent-Bcc']
+        # Remove the X-Peer header that DebuggingServer adds.
+        test_output = self.get_output_without_xpeer()
+        mexpect = '%s%s\n%s' % (MSG_BEGIN, m.as_string(), MSG_END)
+        self.assertEqual(test_output, mexpect)
+        debugout = smtpd.DEBUGSTREAM.getvalue()
+        Date = re.compile(''.join(("\\\\nDate: ", re.escape(current_date))), re.MULTILINE)
+        self.assertRegex(debugout, Date)
+
+
+
 class NonConnectingTests(unittest.TestCase):
 
     def testNotConnected(self):
diff --git a/Misc/NEWS.d/next/Library/2018-01-13-15-52-00.bpo-28879.aW2gj0.rst b/Misc/NEWS.d/next/Library/2018-01-13-15-52-00.bpo-28879.aW2gj0.rst
@@ -0,0 +1,2 @@
+Fix ``smtplib.send_message`` to add a ``Date`` header if it is missing as per
+RFC5322.

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,2 @@`
	`1`	+Fix ``smtplib.send_message`` to add a ``Date`` header if it is missing as per
	`2`	`+RFC5322.`