HF: Replace bip34 with simpler equivalent (coinbase.nLockTime)

Author: jtimon

src/miner.cpp

@@ -182,13 +182,14 @@ std::unique_ptr<CBlockTemplate> BlockAssembler::CreateNewBlock(const CScript& sc
 
     // Create coinbase transaction.
     CMutableTransaction coinbaseTx;
+    coinbaseTx.nLockTime = nHeight - 1;
     coinbaseTx.vin.resize(1);
     coinbaseTx.vin[0].prevout.SetNull();
     coinbaseTx.vout.resize(1);
     coinbaseTx.vout[0].scriptPubKey = nFees ? scriptPubKeyIn : CScript() << OP_RETURN;
     coinbaseTx.vout[0].nValue = nFees;
     coinbaseTx.vout[0].nAsset = policyAsset;
-    coinbaseTx.vin[0].scriptSig = CScript() << nHeight << OP_0;
+    coinbaseTx.vin[0].scriptSig = CScript();
     pblock->vtx[0] = MakeTransactionRef(std::move(coinbaseTx));
     pblocktemplate->vchCoinbaseCommitment = GenerateCoinbaseCommitment(*pblock, pindexPrev, chainparams.GetConsensus());
     pblocktemplate->vTxFees[0] = -nFees;
@@ -633,9 +634,8 @@ void IncrementExtraNonce(CBlock* pblock, const CBlockIndex* pindexPrev, unsigned
         hashPrevBlock = pblock->hashPrevBlock;
     }
     ++nExtraNonce;
-    unsigned int nHeight = pindexPrev->nHeight+1; // Height first in coinbase required for block.version=2
     CMutableTransaction txCoinbase(*pblock->vtx[0]);
-    txCoinbase.vin[0].scriptSig = (CScript() << nHeight << CScriptNum(nExtraNonce)) + COINBASE_FLAGS;
+    txCoinbase.vin[0].scriptSig = (CScript() << CScriptNum(nExtraNonce)) + COINBASE_FLAGS;
     assert(txCoinbase.vin[0].scriptSig.size() <= 100);
 
     pblock->vtx[0] = MakeTransactionRef(std::move(txCoinbase));

src/validation.cpp

@@ -530,7 +530,7 @@ bool CheckTransaction(const CTransaction& tx, CValidationState &state, bool fChe
     if (tx.IsCoinBase())
     {
         // Coinbase transactions may not have eccessive scriptSigs or any fee outputs
-        if (tx.vin[0].scriptSig.size() < 2 || tx.vin[0].scriptSig.size() > 100)
+        if (tx.vin[0].scriptSig.size() > 100)
             return state.DoS(100, false, REJECT_INVALID, "bad-cb-length");
 
         for (unsigned int i = 0; i < tx.vout.size(); i++)
@@ -3848,11 +3848,8 @@ bool ContextualCheckBlock(const CBlock& block, CValidationState& state, const Co
     }
 
     // Enforce rule that the coinbase starts with serialized block height
-    if (block.nVersion >= 2)
-    {
-        CScript expect = CScript() << nHeight;
-        if (block.vtx[0]->vin[0].scriptSig.size() < expect.size() ||
-            !std::equal(expect.begin(), expect.end(), block.vtx[0]->vin[0].scriptSig.begin())) {
+    if (nHeight > consensusParams.BIP34Height) {
+        if (block.vtx[0]->nLockTime != (uint32_t)nHeight - 1) {
             return state.DoS(100, false, REJECT_INVALID, "bad-cb-height", false, "block height mismatch in coinbase");
         }
     }