Blockchain syncing fixed.

libethereum/BlockChain.cpp

@@ -333,16 +333,23 @@ h256s BlockChain::import(bytes const& _block, OverlayDB const& _db)
 
 h256s BlockChain::treeRoute(h256 _from, h256 _to, h256* o_common, bool _pre, bool _post) const
 {
+	cdebug << "treeRoute" << _from.abridged() << "..." << _to.abridged();
+	if (!_from || !_to)
+	{
+		return h256s();
+	}
 	h256s ret;
 	h256s back;
 	unsigned fn = details(_from).number;
 	unsigned tn = details(_to).number;
+	cdebug << "treeRoute" << fn << "..." << tn;
 	while (fn > tn)
 	{
 		if (_pre)
 			ret.push_back(_from);
 		_from = details(_from).parent;
 		fn--;
+		cdebug << "from:" << fn << _from.abridged();
 	}
 	while (fn < tn)
 	{
@@ -350,15 +357,21 @@ h256s BlockChain::treeRoute(h256 _from, h256 _to, h256* o_common, bool _pre, boo
 			back.push_back(_to);
 		_to = details(_to).parent;
 		tn--;
+		cdebug << "to:" << tn << _to.abridged();
 	}
 	while (_from != _to)
 	{
+		assert(_from);
+		assert(_to);
+		_from = details(_from).parent;
+		_to = details(_to).parent;
 		if (_pre)
-			_from = details(_from).parent;
+			ret.push_back(_from);
 		if (_post)
-			_to = details(_to).parent;
-		ret.push_back(_from);
-		back.push_back(_to);
+			back.push_back(_to);
+		fn--;
+		tn--;
+		cdebug << "from:" << fn << _from.abridged() << "; to:" << tn << _to.abridged();
 	}
 	if (o_common)
 		*o_common = _from;

libethereum/EthereumHost.cpp

@@ -571,15 +571,27 @@ void EthereumHost::noteHaveChain(std::shared_ptr<EthereumSession> const& _from)
 {
 	auto td = _from->m_totalDifficulty;
 
+	if (_from->m_neededBlocks.empty())
+		return;
+
+	clog(NetNote) << "Hash-chain COMPLETE:" << log2((double)_from->m_totalDifficulty) << "vs" << log2((double)m_chain->details().totalDifficulty) << "," << log2((double)m_totalDifficultyOfNeeded) << ";" << _from->m_neededBlocks.size() << " blocks, ends" << _from->m_neededBlocks.back().abridged();
+
 	if ((m_totalDifficultyOfNeeded && td < m_totalDifficultyOfNeeded) || td < m_chain->details().totalDifficulty)
+	{
+		clog(NetNote) << "Difficulty of hashchain LOWER. Ignoring.";
 		return;
+	}
+
+	clog(NetNote) << "Difficulty of hashchain HIGHER. Replacing fetch queue.";
 
+	// Looks like it's the best yet for total difficulty. Set to download.
 	{
 		Guard l(x_blocksNeeded);
 		m_blocksNeeded = _from->m_neededBlocks;
+		m_blocksOnWay.clear();
+		m_totalDifficultyOfNeeded = td;
 	}
 
-	// Looks like it's the best yet for total difficulty. Set to download.
 	{
 		Guard l(x_peers);
 		for (auto const& i: m_peers)

libethereum/EthereumSession.cpp

@@ -56,8 +56,19 @@ EthereumSession::~EthereumSession()
 	catch (...){}
 }
 
+string toString(h256s const& _bs)
+{
+	ostringstream out;
+	out << "[ ";
+	for (auto i: _bs)
+		out << i.abridged() << ", ";
+	out << "]";
+	return out.str();
+}
+
 void EthereumSession::giveUpOnFetch()
 {
+	clogS(NetNote) << "GIVE UP FETCH; can't get " << toString(m_askedBlocks);
 	if (m_askedBlocks.size())
 	{
 		Guard l (m_server->x_blocksNeeded);
@@ -329,6 +340,7 @@ bool EthereumSession::interpret(RLP const& _r)
 		}
 		clogS(NetMessageSummary) << dec << knownParents << " known parents, " << unknownParents << "unknown, " << used << "used.";
 		ensureGettingChain();
+		break;
 	}
 	case GetTransactionsPacket:
 	{