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author | Pieter Wuille <pieter.wuille@gmail.com> | 2015-03-19 09:51:59 -0700 |
---|---|---|
committer | Wladimir J. van der Laan <laanwj@gmail.com> | 2015-04-01 16:39:36 +0200 |
commit | 0c6f334c32f2ef5b7224ec7f5ac694153a7f4241 (patch) | |
tree | bf655d2f73990a02b83226e6672db44f0a8bbd63 | |
parent | 214154e6fc65bdc06fbfe1bc04b9b57347fdb3f7 (diff) | |
download | bitcoin-0c6f334c32f2ef5b7224ec7f5ac694153a7f4241.tar.xz |
Always use a 50% chance to choose between tried and new entries
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: c6a63ceeb4956933588995bcf01dc3095aaeb1fc
Github-Pull: #5941
-rw-r--r-- | src/addrman.cpp | 7 | ||||
-rw-r--r-- | src/addrman.h | 6 | ||||
-rw-r--r-- | src/net.cpp | 3 |
3 files changed, 7 insertions, 9 deletions
diff --git a/src/addrman.cpp b/src/addrman.cpp index df32da7257..015589343d 100644 --- a/src/addrman.cpp +++ b/src/addrman.cpp @@ -332,14 +332,13 @@ 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) { diff --git a/src/addrman.h b/src/addrman.h index 3966bf5b73..5eb19758d5 100644 --- a/src/addrman.h +++ b/src/addrman.h @@ -231,7 +231,7 @@ protected: //! 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. @@ -533,13 +533,13 @@ 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) + CAddress Select() { CAddress addrRet; { LOCK(cs); Check(); - addrRet = Select_(nUnkBias); + addrRet = Select_(); Check(); } return addrRet; diff --git a/src/net.cpp b/src/net.cpp index 1d95932ca6..47221edef6 100644 --- a/src/net.cpp +++ b/src/net.cpp @@ -1271,8 +1271,7 @@ 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)) |