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-rw-r--r--src/script/sigcache.cpp91
1 files changed, 57 insertions, 34 deletions
diff --git a/src/script/sigcache.cpp b/src/script/sigcache.cpp
index 099b4ad0e3..eee96e7c2d 100644
--- a/src/script/sigcache.cpp
+++ b/src/script/sigcache.cpp
@@ -5,17 +5,30 @@
#include "sigcache.h"
+#include "memusage.h"
#include "pubkey.h"
#include "random.h"
#include "uint256.h"
#include "util.h"
#include <boost/thread.hpp>
-#include <boost/tuple/tuple_comparison.hpp>
+#include <boost/unordered_set.hpp>
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
* again when accepted into the block chain)
@@ -23,52 +36,54 @@ namespace {
class CSignatureCache
{
private:
- //! sigdata_type is (signature hash, signature, public key):
- typedef boost::tuple<uint256, std::vector<unsigned char>, CPubKey> sigdata_type;
- std::set< sigdata_type> setValid;
+ //! Entries are SHA256(nonce || signature hash || public key || signature):
+ uint256 nonce;
+ typedef boost::unordered_set<uint256, CSignatureCacheHasher> map_type;
+ map_type setValid;
boost::shared_mutex cs_sigcache;
+
public:
+ CSignatureCache()
+ {
+ GetRandBytes(nonce.begin(), 32);
+ }
+
+ void
+ ComputeEntry(uint256& entry, const uint256 &hash, const std::vector<unsigned char>& vchSig, const CPubKey& pubkey)
+ {
+ 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 &hash, const std::vector<unsigned char>& vchSig, const CPubKey& pubKey)
+ Get(const uint256& entry)
{
boost::shared_lock<boost::shared_mutex> lock(cs_sigcache);
+ return setValid.count(entry);
+ }
- sigdata_type k(hash, vchSig, pubKey);
- std::set<sigdata_type>::iterator mi = setValid.find(k);
- if (mi != setValid.end())
- return true;
- return false;
+ void Erase(const uint256& entry)
+ {
+ boost::unique_lock<boost::shared_mutex> lock(cs_sigcache);
+ setValid.erase(entry);
}
- void Set(const uint256 &hash, const std::vector<unsigned char>& vchSig, const CPubKey& pubKey)
+ void Set(const uint256& entry)
{
- // 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);
+ size_t nMaxCacheSize = GetArg("-maxsigcachesize", DEFAULT_MAX_SIG_CACHE_SIZE) * ((size_t) 1 << 20);
if (nMaxCacheSize <= 0) return;
boost::unique_lock<boost::shared_mutex> lock(cs_sigcache);
-
- while (static_cast<int64_t>(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<unsigned char> unused;
- std::set<sigdata_type>::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 +93,21 @@ bool CachingTransactionSignatureChecker::VerifySignature(const std::vector<unsig
{
static CSignatureCache signatureCache;
- if (signatureCache.Get(sighash, vchSig, pubkey))
+ uint256 entry;
+ signatureCache.ComputeEntry(entry, sighash, vchSig, pubkey);
+
+ if (signatureCache.Get(entry)) {
+ if (!store) {
+ signatureCache.Erase(entry);
+ }
return true;
+ }
if (!TransactionSignatureChecker::VerifySignature(vchSig, pubkey, sighash))
return false;
- if (store)
- signatureCache.Set(sighash, vchSig, pubkey);
+ if (store) {
+ signatureCache.Set(entry);
+ }
return true;
}