From 830e3f3d027ba5c8121eed0f6a9ce99961352572 Mon Sep 17 00:00:00 2001 From: Pieter Wuille Date: Fri, 30 Oct 2015 23:14:38 +0100 Subject: [PATCH] Make sigcache faster and more efficient --- src/init.cpp | 3 +- src/script/sigcache.cpp | 86 +++++++++++++++++++++++------------------ src/script/sigcache.h | 4 ++ 3 files changed, 55 insertions(+), 38 deletions(-) diff --git a/src/init.cpp b/src/init.cpp index 76adca769..5843b7d79 100644 --- a/src/init.cpp +++ b/src/init.cpp @@ -25,6 +25,7 @@ #include "policy/policy.h" #include "rpcserver.h" #include "script/standard.h" +#include "script/sigcache.h" #include "scheduler.h" #include "txdb.h" #include "txmempool.h" @@ -434,7 +435,7 @@ std::string HelpMessage(HelpMessageMode mode) strUsage += HelpMessageOpt("-logtimemicros", strprintf("Add microsecond precision to debug timestamps (default: %u)", DEFAULT_LOGTIMEMICROS)); strUsage += HelpMessageOpt("-limitfreerelay=", strprintf("Continuously rate-limit free transactions to *1000 bytes per minute (default: %u)", 15)); strUsage += HelpMessageOpt("-relaypriority", strprintf("Require high priority for relaying free or low-fee transactions (default: %u)", 1)); - strUsage += HelpMessageOpt("-maxsigcachesize=", strprintf("Limit size of signature cache to entries (default: %u)", 50000)); + strUsage += HelpMessageOpt("-maxsigcachesize=", strprintf("Limit size of signature cache to MiB (default: %u)", DEFAULT_MAX_SIG_CACHE_SIZE)); } strUsage += HelpMessageOpt("-minrelaytxfee=", strprintf(_("Fees (in %s/kB) smaller than this are considered zero fee for relaying (default: %s)"), CURRENCY_UNIT, FormatMoney(::minRelayTxFee.GetFeePerK()))); diff --git a/src/script/sigcache.cpp b/src/script/sigcache.cpp index 099b4ad0e..9dc7f0fcd 100644 --- a/src/script/sigcache.cpp +++ b/src/script/sigcache.cpp @@ -5,16 +5,29 @@ #include "sigcache.h" +#include "memusage.h" #include "pubkey.h" #include "random.h" #include "uint256.h" #include "util.h" #include -#include +#include namespace { +/** + * We're hashing a nonce into the entries themselves, so we don't need extra + * blinding in the set hash computation. + */ +class CSignatureCacheHasher +{ +public: + size_t operator()(const uint256& key) const { + return key.GetCheapHash(); + } +}; + /** * Valid signature cache, to avoid doing expensive ECDSA signature checking * twice for every transaction (once when accepted into memory pool, and @@ -23,52 +36,48 @@ namespace { class CSignatureCache { private: - //! sigdata_type is (signature hash, signature, public key): - typedef boost::tuple, CPubKey> sigdata_type; - std::set< sigdata_type> setValid; + //! Entries are SHA256(nonce || signature hash || public key || signature): + uint256 nonce; + typedef boost::unordered_set map_type; + map_type setValid; boost::shared_mutex cs_sigcache; -public: - bool - Get(const uint256 &hash, const std::vector& vchSig, const CPubKey& pubKey) - { - boost::shared_lock lock(cs_sigcache); - sigdata_type k(hash, vchSig, pubKey); - std::set::iterator mi = setValid.find(k); - if (mi != setValid.end()) - return true; - return false; +public: + CSignatureCache() + { + GetRandBytes(nonce.begin(), 32); } - void Set(const uint256 &hash, const std::vector& vchSig, const CPubKey& pubKey) + void + ComputeEntry(uint256& entry, const uint256 &hash, const std::vector& vchSig, const CPubKey& pubkey) { - // DoS prevention: limit cache size to less than 10MB - // (~200 bytes per cache entry times 50,000 entries) - // Since there are a maximum of 20,000 signature operations per block - // 50,000 is a reasonable default. - int64_t nMaxCacheSize = GetArg("-maxsigcachesize", 50000); + CSHA256().Write(nonce.begin(), 32).Write(hash.begin(), 32).Write(&pubkey[0], pubkey.size()).Write(&vchSig[0], vchSig.size()).Finalize(entry.begin()); + } + + bool + Get(const uint256& entry) + { + boost::shared_lock lock(cs_sigcache); + return setValid.count(entry); + } + + void Set(const uint256& entry) + { + size_t nMaxCacheSize = GetArg("-maxsigcachesize", DEFAULT_MAX_SIG_CACHE_SIZE) * ((size_t) 1 << 20); if (nMaxCacheSize <= 0) return; boost::unique_lock lock(cs_sigcache); - - while (static_cast(setValid.size()) > nMaxCacheSize) + while (memusage::DynamicUsage(setValid) > nMaxCacheSize) { - // Evict a random entry. Random because that helps - // foil would-be DoS attackers who might try to pre-generate - // and re-use a set of valid signatures just-slightly-greater - // than our cache size. - uint256 randomHash = GetRandHash(); - std::vector unused; - std::set::iterator it = - setValid.lower_bound(sigdata_type(randomHash, unused, unused)); - if (it == setValid.end()) - it = setValid.begin(); - setValid.erase(*it); + map_type::size_type s = GetRand(setValid.bucket_count()); + map_type::local_iterator it = setValid.begin(s); + if (it != setValid.end(s)) { + setValid.erase(*it); + } } - sigdata_type k(hash, vchSig, pubKey); - setValid.insert(k); + setValid.insert(entry); } }; @@ -78,13 +87,16 @@ bool CachingTransactionSignatureChecker::VerifySignature(const std::vector +// DoS prevention: limit cache size to less than 40MB (over 500000 +// entries on 64-bit systems). +static const unsigned int DEFAULT_MAX_SIG_CACHE_SIZE = 40; + class CPubKey; class CachingTransactionSignatureChecker : public TransactionSignatureChecker