#22215: have the smtplib 'quit' command reset the state.

Without this reset, starttls would fail if a connect/starttls was done after a
quit, because smtplib assumed the existing value of emspt_features was
accurate, but it gets reset when starttls completes (and the new value does
not contain the starttls capability, since tls is already started at that
point).  (There may be additional places where this lack of reset was an
issue as well.)

Patch by Milan Oberkirch.

3 files changed, 23 insertions, 0 deletions

diff --git a/Lib/smtplib.py b/Lib/smtplib.py
index 759b77e..09b4ea6 100755
--- a/Lib/smtplib.py
+++ b/Lib/smtplib.py
@@ -866,6 +866,10 @@ class SMTP:
     def quit(self):
         """Terminate the SMTP session."""
         res = self.docmd("quit")
+        # A new EHLO is required after reconnecting with connect()
+        self.ehlo_resp = self.helo_resp = None
+        self.esmtp_features = {}
+        self.does_esmtp = False
         self.close()
         return res
 
diff --git a/Lib/test/test_smtplib.py b/Lib/test/test_smtplib.py
index 16e90f4..95a9dbe 100644
--- a/Lib/test/test_smtplib.py
+++ b/Lib/test/test_smtplib.py
@@ -858,6 +858,21 @@ class SMTPSimTests(unittest.TestCase):
             self.assertIn(sim_auth_login_password, str(err))
         smtp.close()
 
+    def test_quit_resets_greeting(self):
+        smtp = smtplib.SMTP(HOST, self.port,
+                            local_hostname='localhost',
+                            timeout=15)
+        code, message = smtp.ehlo()
+        self.assertEqual(code, 250)
+        self.assertIn('size', smtp.esmtp_features)
+        smtp.quit()
+        self.assertNotIn('size', smtp.esmtp_features)
+        smtp.connect(HOST, self.port)
+        self.assertNotIn('size', smtp.esmtp_features)
+        smtp.ehlo_or_helo_if_needed()
+        self.assertIn('size', smtp.esmtp_features)
+        smtp.quit()
+
     def test_with_statement(self):
         with smtplib.SMTP(HOST, self.port) as smtp:
             code, message = smtp.noop()
diff --git a/Misc/NEWS b/Misc/NEWS
index ab5eee6..5111b8a 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -27,6 +27,10 @@ Core and Builtins
 Library
 -------
 
+- Issue #22216: smtplib now resets its state more completely after a quit.  The
+  most obvious consequence of the previous behavior was a STARTTLS failure
+  during a connect/starttls/quit/connect/starttls sequence.
+
 - Issue #22185: Fix an occasional RuntimeError in threading.Condition.wait()
   caused by mutation of the waiters queue without holding the lock.  Patch
   by Doug Zongker.