Merge branch 'xcthulhu-quick_check_against_dos' into develop

libdevcore/FixedHash.h

@@ -87,6 +87,8 @@ public:
 	bool operator!=(FixedHash const& _c) const { return m_data != _c.m_data; }
 	bool operator<(FixedHash const& _c) const { for (unsigned i = 0; i < N; ++i) if (m_data[i] < _c.m_data[i]) return true; else if (m_data[i] > _c.m_data[i]) return false; return false; }
 	bool operator>=(FixedHash const& _c) const { return !operator<(_c); }
+	bool operator<=(FixedHash const& _c) const { return operator==(_c) || operator<(_c); }
+	bool operator>(FixedHash const& _c) const { return !operator<=(_c); }
 
 	// The obvious binary operators.
 	FixedHash& operator^=(FixedHash const& _c) { for (unsigned i = 0; i < N; ++i) m_data[i] ^= _c.m_data[i]; return *this; }

libethash/ethash.h

@@ -25,6 +25,17 @@
 #include <stddef.h>
 #include "compiler.h"
 
+#define ETHASH_REVISION 19
+#define ETHASH_DAGSIZE_BYTES_INIT 1073741824U // 2**30
+#define ETHASH_DAG_GROWTH 113000000U
+#define ETHASH_EPOCH_LENGTH 30000U
+#define ETHASH_MIX_BYTES 128
+#define ETHASH_DAG_PARENTS 256
+#define ETHASH_CACHE_ROUNDS 3
+#define ETHASH_ACCESSES 64
+
+// *********************
+// TODO: Remove once other code moved over to compliant naming scheme.
 #define REVISION 19
 #define DAGSIZE_BYTES_INIT 1073741824U // 2**30
 #define DAG_GROWTH 113000000U
@@ -33,6 +44,7 @@
 #define DAG_PARENTS 256
 #define CACHE_ROUNDS 3
 #define ACCESSES 64
+// *********************
 
 #ifdef __cplusplus
 extern "C" {
@@ -82,11 +94,11 @@ static inline int ethash_check_difficulty(
 	return 1;
 }
 
-int ethash_quick_check_difficulty(
+void ethash_quick_hash(
+        uint8_t return_hash[32],
         const uint8_t header_hash[32],
         const uint64_t nonce,
-        const uint8_t mix_hash[32],
-        const uint8_t difficulty[32]);
+        const uint8_t mix_hash[32]);
 
 #ifdef __cplusplus
 }

libethash/internal.h

@@ -37,12 +37,6 @@ void ethash_calculate_dag_item(
         ethash_cache const *cache
 );
 
-void ethash_quick_hash(
-        uint8_t return_hash[32],
-        const uint8_t header_hash[32],
-        const uint64_t nonce,
-        const uint8_t mix_hash[32]);
-
 #ifdef __cplusplus
 }
 #endif

libethcore/Ethasher.cpp

@@ -43,6 +43,12 @@ Ethasher* dev::eth::Ethasher::s_this = nullptr;
 bytes const& Ethasher::cache(BlockInfo const& _header)
 {
 	RecursiveGuard l(x_this);
+	if (_header.number > EPOCH_LENGTH*2048) {
+		std::ostringstream error;
+		error << "block number is too high; max is " << EPOCH_LENGTH*2048 << "(was " << _header.number << ")";
+		throw std::invalid_argument( error.str() );
+ 	}
+
 	if (!m_caches.count(_header.seedHash))
 	{
 		ethash_params p = params((unsigned)_header.number);
@@ -94,7 +100,19 @@ ethash_params Ethasher::params(unsigned _n)
 
 bool Ethasher::verify(BlockInfo const& _header)
 {
-	bigint boundary = (bigint(1) << 256) / _header.difficulty;
+	if (_header.number >= ETHASH_EPOCH_LENGTH * 2048)
+		return false;
+	h256 boundary = u256((bigint(1) << 256) / _header.difficulty);
+	uint8_t quickHashOut[32];
+	ethash_quick_hash(
+		quickHashOut,
+		_header.headerHash(WithoutNonce).data(),
+		(uint64_t)(u64)_header.nonce,
+		_header.mixHash.data()
+	);
+	h256 quickHashOut256 = h256(quickHashOut, h256::ConstructFromPointer);
+	if (quickHashOut256 > boundary)
+		return false;
 	auto e = eval(_header, _header.nonce);
 	return (u256)e.value <= boundary && e.mixHash == _header.mixHash;
 }
@@ -106,4 +124,3 @@ Ethasher::Result Ethasher::eval(BlockInfo const& _header, Nonce const& _nonce)
 	ethash_compute_light(&r, Ethasher::get()->cache(_header).data(), &p, _header.headerHash(WithoutNonce).data(), (uint64_t)(u64)_nonce);
 	return Result{h256(r.result, h256::ConstructFromPointer), h256(r.mix_hash, h256::ConstructFromPointer)};
 }
-