Merge pull request bitcoin#40 from CryptAxe/9517ScriptHeaders

Update coinbase commitments and drivechain scripts

src/miner.cpp

@@ -203,11 +203,11 @@ std::unique_ptr<CBlockTemplate> BlockAssembler::CreateNewBlock(const CScript& sc
             pblock->vtx.push_back(MakeTransactionRef(std::move(wtx)));
     }
 
-    // Add SidechainDB state
-    CTransaction stateTx = CreateSidechainStateTx();
-    for (const CTxOut& out : stateTx.vout) {
-        coinbaseTx.vout.push_back(out);
-        nSideFees += out.nValue;
+    if (scdb.HasState()) {
+        // Add SidechainDB hashMerkleRoot coinbase commitment
+        CTxOut scdbCommit = CreateSCDBHashMerkleRootCommit();
+        nSideFees += scdbCommit.nValue;
+        coinbaseTx.vout.push_back(scdbCommit);
     }
 
     coinbaseTx.vout[0].nValue = nFees + GetBlockSubsidy(nHeight, chainparams.GetConsensus());
@@ -445,15 +445,14 @@ CTransaction BlockAssembler::CreateSidechainWTJoinTx(uint8_t nSidechain)
     return mtx;
 }
 
-CTransaction BlockAssembler::CreateSidechainStateTx()
+CTxOut BlockAssembler::CreateSCDBHashMerkleRootCommit()
 {
-    CMutableTransaction mtx;
-
-    CScript script = scdb.CreateStateScript(nHeight);
-    if (!script.empty())
-        mtx.vout.push_back(CTxOut(CENT, script));
-
-    return mtx;
+    // TODO this call will be replaced when the MT based update PR Is merged.
+    // For now just getting the old style SCDB hash and putting it into the
+    // commitment.
+    const uint256& hashMerkleRoot = scdb.GetSCDBHash();
+    CScript script = GenerateSCDBCoinbaseCommitment(hashMerkleRoot);
+    return CTxOut(CENT, script);
 }
 
 // Skip entries in mapTx that are already in a block or are present

src/miner.h

@@ -208,8 +208,8 @@ class BlockAssembler
     // SidechainDB
     /** Returns a WT^ payout transaction for nSidechain if there is one */
     CTransaction CreateSidechainWTJoinTx(uint8_t nSidechain);
-    /** Returns a SCDB state update transaction (update script in output) */
-    CTransaction CreateSidechainStateTx();
+    /** Returns an output with a commitment to the SCDB hashMerkleRoot */
+    CTxOut CreateSCDBHashMerkleRootCommit();
 };
 
 /** Modify the extranonce in a block */

src/script/script.cpp

@@ -251,7 +251,7 @@ bool CScript::IsWitnessProgram(int& version, std::vector<unsigned char>& program
     return false;
 }
 
-bool CScript::IsBribe() const
+bool CScript::IsBribeHashCommit() const
 {
     // TODO
     // Size must be at least:
@@ -273,6 +273,42 @@ bool CScript::IsBribe() const
     return (this->Find(OP_BRIBE));
 }
 
+bool CScript::IsSCDBHashMerkleRootCommit() const
+{
+    // Check script size
+    size_t size = this->size();
+    if (size != 38) // sha256 hash + opcodes
+        return false;
+
+    // Check script header
+    if ((*this)[0] != OP_RETURN ||
+            (*this)[1] != 0x43 ||
+            (*this)[2] != 0x50 ||
+            (*this)[3] != 0x50 ||
+            (*this)[4] != 0x53)
+        return false;
+
+    return true;
+}
+
+bool CScript::IsWTPrimeHashCommit() const
+{
+    // Check script size
+    size_t size = this->size();
+    if (size < 39 || size > 41) // sha256 hash + nSidechain + opcodes
+        return false;
+
+    // Check script header
+    if ((*this)[0] != OP_RETURN ||
+            (*this)[1] != 0x53 ||
+            (*this)[2] != 0x50 ||
+            (*this)[3] != 0x50 ||
+            (*this)[4] != 0x43)
+        return false;
+
+    return true;
+}
+
 bool CScript::IsPushOnly(const_iterator pc) const
 {
     while (pc < end())

src/script/script.h

@@ -658,7 +658,11 @@ class CScript : public CScriptBase
     bool IsPayToScriptHash() const;
     bool IsPayToWitnessScriptHash() const;
     bool IsWitnessProgram(int& version, std::vector<unsigned char>& program) const;
-    bool IsBribe() const;
+
+    /** Script formats for Drivechains */
+    bool IsBribeHashCommit() const;
+    bool IsSCDBHashMerkleRootCommit() const;
+    bool IsWTPrimeHashCommit() const;
 
     /** Called by IsStandardTx and P2SH/BIP62 VerifyScript (which makes it consensus-critical). */
     bool IsPushOnly(const_iterator pc) const;

src/validation.cpp

@@ -1197,7 +1197,7 @@ bool CScriptCheck::operator()() {
     const CScriptWitness *witness = &ptxTo->vin[nIn].scriptWitness;
 
     std::multimap<uint256, int> mapBMMLDCopy;
-    if (scriptPubKey.IsBribe())
+    if (scriptPubKey.IsBribeHashCommit())
         mapBMMLDCopy = scdb.GetLinkingData();
 
     return VerifyScript(scriptSig, scriptPubKey, witness, nFlags, CachingTransactionSignatureChecker(ptxTo, nIn, amount, cacheStore, *txdata, mapBMMLDCopy), &error);
@@ -2877,6 +2877,47 @@ std::vector<unsigned char> GenerateCoinbaseCommitment(CBlock& block, const CBloc
     return commitment;
 }
 
+CScript GenerateSCDBCoinbaseCommitment(const uint256& hashMerkleRoot)
+{
+    // TODO
+    // check consensusParams.vDeployments[Consensus::DEPLOYMENT_DRIVECHAINS]
+    CScript script;
+
+    // Add script header
+    script << OP_RETURN;
+    script.push_back(0x43);
+    script.push_back(0x50);
+    script.push_back(0x50);
+    script.push_back(0x53);
+
+    // Add SCDB hashMerkleRoot
+    script << ToByteVector(hashMerkleRoot);
+
+    return script;
+}
+
+CScript GenerateBMMCriticalHashCommitment(int nHeight, const uint256& hashCritical)
+{
+    // TODO
+    // check consensusParams.vDeployments[Consensus::DEPLOYMENT_DRIVECHAINS]
+    CScript script;
+
+    // Add script header
+    script << OP_RETURN;
+    script.push_back(0x53);
+    script.push_back(0x50);
+    script.push_back(0x50);
+    script.push_back(0x43);
+
+    // Add block number
+    script << CScriptNum(nHeight);
+
+    // Add h*
+    script << ToByteVector(hashCritical);
+
+    return script;
+}
+
 bool ContextualCheckBlockHeader(const CBlockHeader& block, CValidationState& state, const Consensus::Params& consensusParams, const CBlockIndex* pindexPrev, int64_t nAdjustedTime)
 {
     assert(pindexPrev != NULL);

src/validation.h

@@ -463,6 +463,12 @@ void UpdateUncommittedBlockStructures(CBlock& block, const CBlockIndex* pindexPr
 /** Produce the necessary coinbase commitment for a block (modifies the hash, don't call for mined blocks). */
 std::vector<unsigned char> GenerateCoinbaseCommitment(CBlock& block, const CBlockIndex* pindexPrev, const Consensus::Params& consensusParams);
 
+/** Produce the SCDB hashMerkleRoot coinbase commitment for a block */
+CScript GenerateSCDBCoinbaseCommitment(const uint256& hashMerkleRoot);
+
+/** Produce a BMM h* coinbase commitment for a block */
+CScript GeneratBMMCriticalHashCommitment(int nHeight, const uint256& hashCritical);
+
 /** RAII wrapper for VerifyDB: Verify consistency of the block and coin databases */
 class CVerifyDB {
 public: