From 85c9967b9ce55fd6ea1e2aa59cf065710568661f Mon Sep 17 00:00:00 2001
From: Georg Lukas <georg@op-co.de>
Date: Sat, 28 Mar 2020 21:18:13 +0100
Subject: [PATCH] XEP-0198: fix race conditions on enable/resume

This code splits out the `enabled` property into `enabled_in` and
`enabled_out` to reflect that client and server enable 0198
asynchronously.

This also moves the actual enabling code into the stanza processing
logic, because apparently, `enable.send()` was just added into the end
of the send queue, but `enable` got enabled immediately, so that poezio
requested ACKs for whatever happened to be in the queue before.

Async is hard, let's go get fishing.
---
 slixmpp/plugins/xep_0198/stream_management.py | 36 +++++++++++++------
 1 file changed, 26 insertions(+), 10 deletions(-)

diff --git a/slixmpp/plugins/xep_0198/stream_management.py b/slixmpp/plugins/xep_0198/stream_management.py
index a092736f..2b68faec 100644
--- a/slixmpp/plugins/xep_0198/stream_management.py
+++ b/slixmpp/plugins/xep_0198/stream_management.py
@@ -71,7 +71,8 @@ class XEP_0198(BasePlugin):
 
         self.window_counter = self.window
 
-        self.enabled = False
+        self.enabled_in = False
+        self.enabled_out = False
         self.unacked_queue = collections.deque()
 
         register_stanza_plugin(StreamFeatures, stanza.StreamManagement)
@@ -158,11 +159,17 @@ class XEP_0198(BasePlugin):
 
     def disconnected(self, event):
         """Reset enabled state until we can resume/reenable."""
-        self.enabled = False
+        log.debug("disconnected, disabling SM")
+        self.xmpp.event('sm_disabled', event)
+        self.enabled_in = False
+        self.enabled_out = False
 
     def session_end(self, event):
         """Reset stream management state."""
-        self.enabled = False
+        log.debug("session_end, disabling SM")
+        self.xmpp.event('sm_disabled', event)
+        self.enabled_in = False
+        self.enabled_out = False
         self.unacked_queue.clear()
         self.sm_id = None
         self.handled = 0
@@ -177,6 +184,7 @@ class XEP_0198(BasePlugin):
 
     def request_ack(self, e=None):
         """Request an ack from the server."""
+        log.debug("requesting ack")
         req = stanza.RequestAck(self.xmpp)
         self.xmpp.send_raw(str(req))
 
@@ -199,9 +207,7 @@ class XEP_0198(BasePlugin):
                 enable = stanza.Enable(self.xmpp)
                 enable['resume'] = self.allow_resume
                 enable.send()
-                self.enabled = True
-                self.handled = 0
-                self.unacked_queue.clear()
+                log.debug("enabling SM")
 
                 waiter = Waiter('enabled_or_failed',
                         MatchMany([
@@ -210,11 +216,11 @@ class XEP_0198(BasePlugin):
                 self.xmpp.register_handler(waiter)
                 result = await waiter.wait()
         elif self.sm_id and self.allow_resume and 'bind' not in self.xmpp.features:
-            self.enabled = True
             resume = stanza.Resume(self.xmpp)
             resume['h'] = self.handled
             resume['previd'] = self.sm_id
             resume.send()
+            log.debug("resuming SM")
 
             # Wait for a response before allowing stream feature processing
             # to continue. The actual result processing will be done in the
@@ -237,6 +243,8 @@ class XEP_0198(BasePlugin):
         self.xmpp.features.add('stream_management')
         if stanza['id']:
             self.sm_id = stanza['id']
+        self.enabled_in = True
+        self.handled = 0
         self.xmpp.event('sm_enabled', stanza)
 
     def _handle_resumed(self, stanza):
@@ -245,6 +253,7 @@ class XEP_0198(BasePlugin):
         Raises a :term:`session_resumed` event.
         """
         self.xmpp.features.add('stream_management')
+        self.enabled_in = True
         self._handle_ack(stanza)
         for id, stanza in self.unacked_queue:
             self.xmpp.send(stanza, use_filters=False)
@@ -258,7 +267,8 @@ class XEP_0198(BasePlugin):
 
         Raises an :term:`sm_failed` event.
         """
-        self.enabled = False
+        self.enabled_in = False
+        self.enabled_out = False
         self.unacked_queue.clear()
         self.xmpp.event('sm_failed', stanza)
 
@@ -295,7 +305,7 @@ class XEP_0198(BasePlugin):
 
     def _handle_incoming(self, stanza):
         """Increment the handled counter for each inbound stanza."""
-        if not self.enabled:
+        if not self.enabled_in:
             return stanza
 
         if isinstance(stanza, (Message, Presence, Iq)):
@@ -305,7 +315,13 @@ class XEP_0198(BasePlugin):
 
     def _handle_outgoing(self, stanza):
         """Store outgoing stanzas in a queue to be acked."""
-        if not self.enabled:
+        from slixmpp.plugins.xep_0198 import stanza as st
+        if isinstance(stanza, (st.Enable, st.Resume)):
+            self.enabled_out = True
+            self.unacked_queue.clear()
+            log.debug("enabling outgoing SM: %s" % stanza)
+
+        if not self.enabled_out:
             return stanza
 
         if isinstance(stanza, (Message, Presence, Iq)):