From 2513561a33286254bbff68b203ff32113d86fee4 Mon Sep 17 00:00:00 2001
From: Gav Wood <i@gavwood.com>
Date: Tue, 28 Jul 2015 23:31:12 +0200
Subject: [PATCH] Avoid mining invalid blocks. Actually allow external mining.

---
 libethcore/BlockInfo.cpp | 2 +-
 libethcore/Ethash.cpp    | 9 ++++++++-
 libethcore/Ethash.h      | 2 ++
 libethereum/Client.cpp   | 1 +
 libethereum/State.cpp    | 6 +++++-
 5 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/libethcore/BlockInfo.cpp b/libethcore/BlockInfo.cpp
index 6252497b5..5cf909959 100644
--- a/libethcore/BlockInfo.cpp
+++ b/libethcore/BlockInfo.cpp
@@ -176,7 +176,7 @@ void BlockInfo::verifyInternals(bytesConstRef _block) const
 	}
 	clog(BlockInfoDiagnosticsChannel) << "Expected uncle hash:" << toString(sha3(root[2].data()));
 	if (m_sha3Uncles != sha3(root[2].data()))
-		BOOST_THROW_EXCEPTION(InvalidUnclesHash());
+		BOOST_THROW_EXCEPTION(InvalidUnclesHash() << Hash256RequirementError(sha3(root[2].data()), m_sha3Uncles));
 }
 
 void BlockInfo::populateFromParent(BlockInfo const& _parent)
diff --git a/libethcore/Ethash.cpp b/libethcore/Ethash.cpp
index 101fd1611..511146b75 100644
--- a/libethcore/Ethash.cpp
+++ b/libethcore/Ethash.cpp
@@ -177,15 +177,22 @@ StringHashMap Ethash::BlockHeaderRaw::jsInfo() const
 	return { { "nonce", toJS(m_nonce) }, { "seedHash", toJS(seedHash()) }, { "mixHash", toJS(m_mixHash) } };
 }
 
-
+void Ethash::manuallySetWork(SealEngineFace* _engine, BlockHeader const& _work)
+{
+	// set m_sealing to the current problem.
+	if (EthashSealEngine* e = dynamic_cast<EthashSealEngine*>(_engine))
+		e->m_sealing = _work;
+}
 
 void Ethash::manuallySubmitWork(SealEngineFace* _engine, h256 const& _mixHash, Nonce _nonce)
 {
 	if (EthashSealEngine* e = dynamic_cast<EthashSealEngine*>(_engine))
+	{
 		// Go via the farm since the handler function object is stored as a local within the Farm's lambda.
 		// Has the side effect of stopping local workers, which is good, as long as it only does it for
 		// valid submissions.
 		static_cast<GenericFarmFace<EthashProofOfWork>&>(e->m_farm).submitProof(EthashProofOfWork::Solution{_nonce, _mixHash}, nullptr);
+	}
 }
 
 bool Ethash::isWorking(SealEngineFace* _engine)
diff --git a/libethcore/Ethash.h b/libethcore/Ethash.h
index 0ea80f5e1..a0904fa62 100644
--- a/libethcore/Ethash.h
+++ b/libethcore/Ethash.h
@@ -99,6 +99,8 @@ public:
 	};
 	using BlockHeader = BlockHeaderPolished<BlockHeaderRaw>;
 
+	static void manuallySetWork(SealEngineFace* _engine, BlockHeader const& _work);
+
 	// TODO: Move elsewhere (EthashAux?)
 	static void ensurePrecomputed(unsigned _number);
 };
diff --git a/libethereum/Client.cpp b/libethereum/Client.cpp
index 7a9172a90..2322d1e46 100644
--- a/libethereum/Client.cpp
+++ b/libethereum/Client.cpp
@@ -924,6 +924,7 @@ std::tuple<h256, h256, h256> EthashClient::getEthashWork()
 		// otherwise, set this to true so that it gets prepped next time.
 		m_remoteWorking = true;
 	Ethash::BlockHeader bh = Ethash::BlockHeader(m_miningInfo);
+	Ethash::manuallySetWork(m_sealEngine.get(), bh);
 	return std::tuple<h256, h256, h256>(bh.hashWithout(), bh.seedHash(), bh.boundary());
 }
 
diff --git a/libethereum/State.cpp b/libethereum/State.cpp
index 3127ad1f6..b8c0ce89c 100644
--- a/libethereum/State.cpp
+++ b/libethereum/State.cpp
@@ -906,8 +906,12 @@ bool State::sealBlock(bytesConstRef _header)
 	if (!m_committedToMine)
 		return false;
 
+	// Check that this header is indeed for this block.
+	if (BlockInfo(_header, CheckNothing, h256{}, HeaderData).hashWithout() != m_currentBlock.hashWithout())
+		return false;
+
+	// Looks good!
 	clog(StateDetail) << "Sealing block!";
-	// Got it!
 
 	// Compile block:
 	RLPStream ret;