AlethZero fixes.

libethcore/BlockInfo.cpp

@@ -23,6 +23,7 @@
 #include <libdevcore/RLP.h>
 #include <libdevcrypto/TrieDB.h>
 #include <libethcore/Common.h>
+#include "EthashAux.h"
 #include "ProofOfWork.h"
 #include "Exceptions.h"
 #include "Params.h"
@@ -63,8 +64,7 @@ void BlockInfo::clear()
 h256 const& BlockInfo::seedHash() const
 {
 	if (!m_seedHash)
-		for (u256 n = number; n >= c_epochDuration; n -= c_epochDuration)
+		m_seedHash = EthashAux::seedHash((unsigned)number);
-			m_seedHash = sha3(m_seedHash);
 	return m_seedHash;
 }
 
@@ -145,9 +145,14 @@ void BlockInfo::populateFromHeader(RLP const& _header, Strictness _s, h256 const
 		throw;
 	}
 
+	if (number > ~(unsigned)0)
+		throw InvalidNumber();
+
 	// check it hashes according to proof of work or that it's the genesis block.
 	if (_s == CheckEverything && parentHash && !ProofOfWork::verify(*this))
 		BOOST_THROW_EXCEPTION(InvalidBlockNonce() << errinfo_hash256(headerHash(WithoutNonce)) << errinfo_nonce(nonce) << errinfo_difficulty(difficulty));
+	else if (_s == QuickNonce && parentHash && !ProofOfWork::preVerify(*this))
+		BOOST_THROW_EXCEPTION(InvalidBlockNonce() << errinfo_hash256(headerHash(WithoutNonce)) << errinfo_nonce(nonce) << errinfo_difficulty(difficulty));
 
 	if (_s != CheckNothing)
 	{

libethcore/BlockInfo.h

@@ -39,6 +39,7 @@ enum IncludeNonce
 enum Strictness
 {
 	CheckEverything,
+	QuickNonce,
 	IgnoreNonce,
 	CheckNothing
 };

libethcore/EthashAux.cpp

@@ -63,24 +63,47 @@ ethash_params EthashAux::params(unsigned _n)
 	return p;
 }
 
+h256 EthashAux::seedHash(unsigned _number)
+{
+	unsigned epoch = _number / ETHASH_EPOCH_LENGTH;
+	RecursiveGuard l(get()->x_this);
+	if (_number < get()->m_seedHashes.size())
+		return get()->m_seedHashes[_number];
+	h256 ret;
+	unsigned n = 0;
+	if (!get()->m_seedHashes.empty())
+	{
+		ret = get()->m_seedHashes.back();
+		n = get()->m_seedHashes.size() - 1;
+	}
+	cdebug << "Searching for seedHash of epoch " << epoch;
+	for (; n < epoch; ++n, ret = sha3(ret))
+		cdebug << "Epoch" << n << "is" << ret.abridged();
+	return ret;
+}
+
 ethash_params EthashAux::params(h256 const& _seedHash)
 {
 	RecursiveGuard l(get()->x_this);
 	unsigned epoch = 0;
 	try
 	{
-		epoch = get()->m_seedHashes.at(_seedHash);
+		epoch = get()->m_epochs.at(_seedHash);
 	}
 	catch (...)
 	{
-		for (h256 h; h != _seedHash && epoch < 2048; ++epoch, h = h256(h)) {}
+		cdebug << "Searching for seedHash " << _seedHash.abridged();
+		for (h256 h; h != _seedHash && epoch < 2048; ++epoch, h = sha3(h))
+		{
+			cdebug << "Epoch" << epoch << "is" << h.abridged();
+		}
 		if (epoch == 2048)
 		{
 			std::ostringstream error;
 			error << "apparent block number for " << _seedHash.abridged() << " is too high; max is " << (ETHASH_EPOCH_LENGTH * 2048);
 			throw std::invalid_argument(error.str());
 		}
-		get()->m_seedHashes[_seedHash] = epoch;
+		get()->m_epochs[_seedHash] = epoch;
 	}
 	return params(epoch * ETHASH_EPOCH_LENGTH);
 }

libethcore/EthashAux.h

@@ -36,6 +36,7 @@ public:
 	using LightType = void const*;
 	using FullType = void const*;
 
+	static h256 seedHash(unsigned _number);
 	static ethash_params params(BlockInfo const& _header);
 	static ethash_params params(h256 const& _seedHash);
 	static ethash_params params(unsigned _n);
@@ -58,7 +59,8 @@ private:
 
 	std::map<h256, LightType> m_lights;
 	std::map<h256, bytesRef> m_fulls;
-	std::map<h256, unsigned> m_seedHashes;
+	std::map<h256, unsigned> m_epochs;
+	h256s m_seedHashes;
 };
 
 }