Issue #10287: nntplib now queries the server's CAPABILITIES first before sending MODE READER, and only sends it if not already in READER mode.
Patch by Hynek Schlawack.
diff --git a/Lib/nntplib.py b/Lib/nntplib.py
index 6b0150d..32bffd8 100644
--- a/Lib/nntplib.py
+++ b/Lib/nntplib.py
@@ -324,25 +324,30 @@
self.debugging = 0
self.welcome = self._getresp()
+ # Inquire about capabilities (RFC 3977).
+ self._caps = None
+ self.getcapabilities()
+
# 'MODE READER' is sometimes necessary to enable 'reader' mode.
# However, the order in which 'MODE READER' and 'AUTHINFO' need to
# arrive differs between some NNTP servers. If _setreadermode() fails
# with an authorization failed error, it will set this to True;
# the login() routine will interpret that as a request to try again
# after performing its normal function.
+ # Enable only if we're not already in READER mode anyway.
self.readermode_afterauth = False
- if readermode:
+ if readermode and 'READER' not in self._caps:
self._setreadermode()
+ if not self.readermode_afterauth:
+ # Capabilities might have changed after MODE READER
+ self._caps = None
+ self.getcapabilities()
# RFC 4642 2.2.2: Both the client and the server MUST know if there is
# a TLS session active. A client MUST NOT attempt to start a TLS
# session if a TLS session is already active.
self.tls_on = False
- # Inquire about capabilities (RFC 3977).
- self._caps = None
- self.getcapabilities()
-
# Log in and encryption setup order is left to subclasses.
self.authenticated = False
@@ -945,8 +950,12 @@
self._caps = None
self.getcapabilities()
# Attempt to send mode reader if it was requested after login.
- if self.readermode_afterauth:
+ # Only do so if we're not in reader mode already.
+ if self.readermode_afterauth and 'READER' not in self._caps:
self._setreadermode()
+ # Capabilities might have changed after MODE READER
+ self._caps = None
+ self.getcapabilities()
def _setreadermode(self):
try:
diff --git a/Lib/test/test_nntplib.py b/Lib/test/test_nntplib.py
index 23fb647..179d31e 100644
--- a/Lib/test/test_nntplib.py
+++ b/Lib/test/test_nntplib.py
@@ -364,6 +364,12 @@
return self.server
+class MockedNNTPWithReaderModeMixin(MockedNNTPTestsMixin):
+ def setUp(self):
+ super().setUp()
+ self.make_server(readermode=True)
+
+
class NNTPv1Handler:
"""A handler for RFC 977"""
@@ -704,6 +710,9 @@
else:
self.push_lit(fmt.format(''))
+ def handle_MODE(self, _):
+ raise Exception('MODE READER sent despite READER has been advertised')
+
def handle_OVER(self, message_spec=None):
return self.handle_XOVER(message_spec)
@@ -718,6 +727,34 @@
super().handle_CAPABILITIES()
+class ModeSwitchingNNTPv2Handler(NNTPv2Handler):
+ """A server that starts in transit mode"""
+
+ def __init__(self):
+ self._switched = False
+
+ def handle_CAPABILITIES(self):
+ fmt = """\
+ 101 Capability list:
+ VERSION 2 3
+ IMPLEMENTATION INN 2.5.1
+ HDR
+ LIST ACTIVE ACTIVE.TIMES DISTRIB.PATS HEADERS NEWSGROUPS OVERVIEW.FMT
+ OVER
+ POST
+ {}READER
+ ."""
+ if self._switched:
+ self.push_lit(fmt.format(''))
+ else:
+ self.push_lit(fmt.format('MODE-'))
+
+ def handle_MODE(self, what):
+ assert not self._switched and what == 'reader'
+ self._switched = True
+ self.push_lit('200 Posting allowed')
+
+
class NNTPv1v2TestsMixin:
def setUp(self):
@@ -1124,6 +1161,18 @@
self.assertIn('VERSION', self.server._caps)
+class SendReaderNNTPv2Tests(MockedNNTPWithReaderModeMixin,
+ unittest.TestCase):
+ """Same tests as for v2 but we tell NTTP to send MODE READER to a server
+ that isn't in READER mode by default."""
+
+ nntp_version = 2
+ handler_class = ModeSwitchingNNTPv2Handler
+
+ def test_we_are_in_reader_mode_after_connect(self):
+ self.assertIn('READER', self.server._caps)
+
+
class MiscTests(unittest.TestCase):
def test_decode_header(self):
@@ -1284,7 +1333,7 @@
def test_main():
tests = [MiscTests, NNTPv1Tests, NNTPv2Tests, CapsAfterLoginNNTPv2Tests,
- NetworkedNNTPTests]
+ SendReaderNNTPv2Tests, NetworkedNNTPTests]
if _have_ssl:
tests.append(NetworkedNNTP_SSLTests)
support.run_unittest(*tests)
diff --git a/Misc/NEWS b/Misc/NEWS
index 6180361a..06ce404 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -113,6 +113,10 @@
Library
-------
+- Issue #10287: nntplib now queries the server's CAPABILITIES first before
+ sending MODE READER, and only sends it if not already in READER mode.
+ Patch by Hynek Schlawack.
+
- Issue #13979: A bug in ctypes.util.find_library that caused
the wrong library name to be returned has been fixed.