maxmustermann/dogecoin
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Always use a 50% chance to choose between tried and new entries

Browse source 
This change was suggested as Countermeasure 2 in
Eclipse Attacks on Bitcoin’s Peer-to-Peer Network, Ethan Heilman,
Alison Kendler, Aviv Zohar, Sharon Goldberg. ePrint Archive Report
2015/263. March 2015.

Rebased-From: c6a63ceeb4
Github-Pull: #5941
This commit is contained in:
Pieter Wuille 2015-03-19 09:51:59 -07:00 committed by Ross Nicoll
parent 7902f4cc01
commit 9b95692530
3 changed files with 10 additions and 13 deletions
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8
src/addrman.cpp
View file

@ -329,15 +329,13 @@ void CAddrMan::Attempt_(const CService &addr, int64_t nTime)
info.nAttempts++;
}
CAddress CAddrMan::Select_(int nUnkBias)
CAddress CAddrMan::Select_()
{
if (size() == 0)
return CAddress();
double nCorTried = sqrt(nTried) * (100.0 - nUnkBias);
double nCorNew = sqrt(nNew) * nUnkBias;
if ((nCorTried + nCorNew)*GetRandInt(1<<30)/(1<<30) < nCorTried)
{
// Use a 50% chance for choosing between tried and new table entries.
if (nTried > 0 && (nNew == 0 || GetRandInt(2) == 0)) {
// use a tried node
double fChanceFactor = 1.0;
while (1) {

12
src/addrman.h
View file

@ -225,8 +225,7 @@ protected:
void Attempt_(const CService &addr, int64_t nTime);
// Select an address to connect to.
// nUnkBias determines how much to favor new addresses over tried ones (min=0, max=100)
CAddress Select_(int nUnkBias);
CAddress Select_();
#ifdef DEBUG_ADDRMAN
// Perform consistency check. Returns an error code or zero.
@ -524,15 +523,16 @@ public:
}
}
// Choose an address to connect to.
// nUnkBias determines how much "new" entries are favored over "tried" ones (0-100).
CAddress Select(int nUnkBias = 50)
/**
* Choose an address to connect to.
*/
CAddress Select()
{
CAddress addrRet;
{
LOCK(cs);
Check();
addrRet = Select_(nUnkBias);
addrRet = Select_();
Check();
}
return addrRet;

3
src/net.cpp
View file

@ -1360,8 +1360,7 @@ void ThreadOpenConnections()
int nTries = 0;
while (true)
{
// use an nUnkBias between 10 (no outgoing connections) and 90 (8 outgoing connections)
CAddress addr = addrman.Select(10 + min(nOutbound,8)*10);
CAddress addr = addrman.Select();
// if we selected an invalid address, restart
if (!addr.IsValid() || setConnected.count(addr.GetGroup()) || IsLocal(addr))