From 5400ef6bcb9d243b2b21697775aa6491115420f3 Mon Sep 17 00:00:00 2001
From: Pieter Wuille <pieter.wuille@gmail.com>
Date: Wed, 8 Apr 2015 11:20:00 -0700
Subject: Replace trickle nodes with per-node/message Poisson delays

We used to have a trickle node, a node which was chosen in each iteration of
the send loop that was privileged and allowed to send out queued up non-time
critical messages. Since the removal of the fixed sleeps in the network code,
this resulted in fast and attackable treatment of such broadcasts.

This pull request changes the 3 remaining trickle use cases by random delays:
* Local address broadcast (while also removing the the wiping of the seen filter)
* Address relay
* Inv relay (for transactions; blocks are always relayed immediately)

The code is based on older commits by Patrick Strateman.
---
 src/net.h | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

(limited to 'src/net.h')

diff --git a/src/net.h b/src/net.h
index 3ed438605e..bc64571aeb 100644
--- a/src/net.h
+++ b/src/net.h
@@ -113,7 +113,7 @@ struct CNodeSignals
 {
     boost::signals2::signal<int ()> GetHeight;
     boost::signals2::signal<bool (CNode*), CombinerAll> ProcessMessages;
-    boost::signals2::signal<bool (CNode*, bool), CombinerAll> SendMessages;
+    boost::signals2::signal<bool (CNode*), CombinerAll> SendMessages;
     boost::signals2::signal<void (NodeId, const CNode*)> InitializeNode;
     boost::signals2::signal<void (NodeId)> FinalizeNode;
 };
@@ -391,6 +391,8 @@ public:
     CRollingBloomFilter addrKnown;
     bool fGetAddr;
     std::set<uint256> setKnown;
+    int64_t nNextAddrSend;
+    int64_t nNextLocalAddrSend;
 
     // inventory based relay
     CRollingBloomFilter filterInventoryKnown;
@@ -398,6 +400,7 @@ public:
     CCriticalSection cs_inventory;
     std::set<uint256> setAskFor;
     std::multimap<int64_t, CInv> mapAskFor;
+    int64_t nNextInvSend;
     // Used for headers announcements - unfiltered blocks to relay
     // Also protected by cs_inventory
     std::vector<uint256> vBlockHashesToAnnounce;
@@ -791,4 +794,7 @@ public:
 
 void DumpBanlist();
 
+/** Return a timestamp in the future (in microseconds) for exponentially distributed events. */
+int64_t PoissonNextSend(int64_t nNow, int average_interval_seconds);
+
 #endif // BITCOIN_NET_H
-- 
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