From 465a276c02823f8f53b25e6ab93f49cfeca211c7 Mon Sep 17 00:00:00 2001
From: Peter Surda <surda@economicsofbitcoin.com>
Date: Thu, 11 Jul 2019 10:51:10 +0200
Subject: [PATCH] Dandelion fixes

- expiration wasn't handled correctly
- objects with no child stems never expired. While this is better for
  anonymity, it can cause objects getting stuck
- upon expiration the nodes weren't marked as not having the object, causing it
  to not be advertised
- I haven't tested it but at least I don't think can make things worse
---
 src/network/dandelion.py |  6 ++++--
 src/network/invthread.py | 28 +++++++++++++++++++++++++---
 2 files changed, 29 insertions(+), 5 deletions(-)

diff --git a/src/network/dandelion.py b/src/network/dandelion.py
index 06ecca24..e3464dae 100644
--- a/src/network/dandelion.py
+++ b/src/network/dandelion.py
@@ -122,11 +122,13 @@ class Dandelion():
     def expire(self):
         with self.lock:
             deadline = time()
-            # only expire those that have a child node, i.e. those without a child not will stick around
-            toDelete = [[v.stream, k, v.child] for k, v in self.hashMap.iteritems() if v.timeout < deadline and v.child]
+            toDelete = [[v.stream, k, v.child]
+                        for k, v in self.hashMap.iteritems()
+                        if v.timeout < deadline]
             for row in toDelete:
                 self.removeHash(row[1], 'expiration')
                 invQueue.put((row[0], row[1], row[2]))
+        return toDelete
 
     def reRandomiseStems(self):
         with self.lock:
diff --git a/src/network/invthread.py b/src/network/invthread.py
index d0d758fb..6f6f1364 100644
--- a/src/network/invthread.py
+++ b/src/network/invthread.py
@@ -12,6 +12,27 @@ from queues import invQueue
 import protocol
 import state
 
+
+def handleExpiredDandelion(expired):
+    """For expired dandelion objects, mark all remotes as not having
+       the object"""
+    if not expired:
+        return
+    for i in \
+        BMConnectionPool().inboundConnections.values() + \
+            BMConnectionPool().outboundConnections.values():
+        if not i.fullyEstablished:
+            continue
+        for x in expired:
+            streamNumber, hashid, _ = x
+            try:
+                del i.objectsNewToMe[hashid]
+            except KeyError:
+                if streamNumber in i.streams:
+                    with i.objectsNewToThemLock:
+                        i.objectsNewToThem[hashid] = time()
+
+
 class InvThread(threading.Thread, StoppableThread):
     def __init__(self):
         threading.Thread.__init__(self, name="InvBroadcaster")
@@ -20,8 +41,9 @@ class InvThread(threading.Thread, StoppableThread):
 
     def handleLocallyGenerated(self, stream, hashId):
         Dandelion().addHash(hashId, stream=stream)
-        for connection in BMConnectionPool().inboundConnections.values() + \
-            BMConnectionPool().outboundConnections.values():
+        for connection in \
+                BMConnectionPool().inboundConnections.values() + \
+                BMConnectionPool().outboundConnections.values():
                 if state.dandelion and connection != Dandelion().objectChildStem(hashId):
                     continue
                 connection.objectsNewToThem[hashId] = time()
@@ -31,7 +53,7 @@ class InvThread(threading.Thread, StoppableThread):
             chunk = []
             while True:
                 # Dandelion fluff trigger by expiration
-                Dandelion().expire()
+                handleExpiredDandelion(Dandelion().expire())
                 try:
                     data = invQueue.get(False)
                     chunk.append((data[0], data[1]))