validation: move GetWitnessCommitmentIndex to consensus/validation

Author: kallewoof

src/consensus/validation.h

@@ -12,6 +12,12 @@
 #include <primitives/transaction.h>
 #include <primitives/block.h>
 
+/** Index marker for when no witness commitment is present in a coinbase transaction. */
+static constexpr int NO_WITNESS_COMMITMENT{-1};
+
+/** Minimum size of a witness commitment structure. Defined in BIP 141. **/
+static constexpr size_t MINIMUM_WITNESS_COMMITMENT{38};
+
 /** A "reason" why a transaction was invalid, suitable for determining whether the
   * provider of the transaction should be banned/ignored/disconnected/etc.
   */
@@ -151,4 +157,25 @@ static inline int64_t GetTransactionInputWeight(const CTxIn& txin)
     return ::GetSerializeSize(txin, PROTOCOL_VERSION | SERIALIZE_TRANSACTION_NO_WITNESS) * (WITNESS_SCALE_FACTOR - 1) + ::GetSerializeSize(txin, PROTOCOL_VERSION) + ::GetSerializeSize(txin.scriptWitness.stack, PROTOCOL_VERSION);
 }
 
+/** Compute at which vout of the block's coinbase transaction the witness commitment occurs, or -1 if not found */
+inline int GetWitnessCommitmentIndex(const CBlock& block)
+{
+    int commitpos = NO_WITNESS_COMMITMENT;
+    if (!block.vtx.empty()) {
+        for (size_t o = 0; o < block.vtx[0]->vout.size(); o++) {
+            const CTxOut& vout = block.vtx[0]->vout[o];
+            if (vout.scriptPubKey.size() >= MINIMUM_WITNESS_COMMITMENT &&
+                vout.scriptPubKey[0] == OP_RETURN &&
+                vout.scriptPubKey[1] == 0x24 &&
+                vout.scriptPubKey[2] == 0xaa &&
+                vout.scriptPubKey[3] == 0x21 &&
+                vout.scriptPubKey[4] == 0xa9 &&
+                vout.scriptPubKey[5] == 0xed) {
+                commitpos = o;
+            }
+        }
+    }
+    return commitpos;
+}
+
 #endif // BITCOIN_CONSENSUS_VALIDATION_H

src/validation.cpp

@@ -3395,31 +3395,11 @@ bool IsWitnessEnabled(const CBlockIndex* pindexPrev, const Consensus::Params& pa
     return (height >= params.SegwitHeight);
 }
 
-int GetWitnessCommitmentIndex(const CBlock& block)
-{
-    int commitpos = -1;
-    if (!block.vtx.empty()) {
-        for (size_t o = 0; o < block.vtx[0]->vout.size(); o++) {
-            const CTxOut& vout = block.vtx[0]->vout[o];
-            if (vout.scriptPubKey.size() >= MINIMUM_WITNESS_COMMITMENT &&
-                vout.scriptPubKey[0] == OP_RETURN &&
-                vout.scriptPubKey[1] == 0x24 &&
-                vout.scriptPubKey[2] == 0xaa &&
-                vout.scriptPubKey[3] == 0x21 &&
-                vout.scriptPubKey[4] == 0xa9 &&
-                vout.scriptPubKey[5] == 0xed) {
-                commitpos = o;
-            }
-        }
-    }
-    return commitpos;
-}
-
 void UpdateUncommittedBlockStructures(CBlock& block, const CBlockIndex* pindexPrev, const Consensus::Params& consensusParams)
 {
     int commitpos = GetWitnessCommitmentIndex(block);
     static const std::vector<unsigned char> nonce(32, 0x00);
-    if (commitpos != -1 && IsWitnessEnabled(pindexPrev, consensusParams) && !block.vtx[0]->HasWitness()) {
+    if (commitpos != NO_WITNESS_COMMITMENT && IsWitnessEnabled(pindexPrev, consensusParams) && !block.vtx[0]->HasWitness()) {
         CMutableTransaction tx(*block.vtx[0]);
         tx.vin[0].scriptWitness.stack.resize(1);
         tx.vin[0].scriptWitness.stack[0] = nonce;
@@ -3433,7 +3413,7 @@ std::vector<unsigned char> GenerateCoinbaseCommitment(CBlock& block, const CBloc
     int commitpos = GetWitnessCommitmentIndex(block);
     std::vector<unsigned char> ret(32, 0x00);
     if (consensusParams.SegwitHeight != std::numeric_limits<int>::max()) {
-        if (commitpos == -1) {
+        if (commitpos == NO_WITNESS_COMMITMENT) {
             uint256 witnessroot = BlockWitnessMerkleRoot(block, nullptr);
             CHash256().Write(witnessroot).Write(ret).Finalize(witnessroot);
             CTxOut out;
@@ -3571,7 +3551,7 @@ static bool ContextualCheckBlock(const CBlock& block, BlockValidationState& stat
     bool fHaveWitness = false;
     if (nHeight >= consensusParams.SegwitHeight) {
         int commitpos = GetWitnessCommitmentIndex(block);
-        if (commitpos != -1) {
+        if (commitpos != NO_WITNESS_COMMITMENT) {
             bool malleated = false;
             uint256 hashWitness = BlockWitnessMerkleRoot(block, &malleated);
             // The malleation check is ignored; as the transaction tree itself

src/validation.h

@@ -93,8 +93,6 @@ static const unsigned int DEFAULT_CHECKLEVEL = 3;
 // one 128MB block file + added 15% undo data = 147MB greater for a total of 545MB
 // Setting the target to >= 550 MiB will make it likely we can respect the target.
 static const uint64_t MIN_DISK_SPACE_FOR_BLOCK_FILES = 550 * 1024 * 1024;
-/** Minimum size of a witness commitment structure. Defined in BIP 141. **/
-static constexpr size_t MINIMUM_WITNESS_COMMITMENT{38};
 
 struct BlockHasher
 {
@@ -306,9 +304,6 @@ bool TestBlockValidity(BlockValidationState& state, const CChainParams& chainpar
  *  Note that transaction witness validation rules are always enforced when P2SH is enforced. */
 bool IsWitnessEnabled(const CBlockIndex* pindexPrev, const Consensus::Params& params);
 
-/** Compute at which vout of the block's coinbase transaction the witness commitment occurs, or -1 if not found */
-int GetWitnessCommitmentIndex(const CBlock& block);
-
 /** Update uncommitted block structures (currently: only the witness reserved value). This is safe for submitted blocks. */
 void UpdateUncommittedBlockStructures(CBlock& block, const CBlockIndex* pindexPrev, const Consensus::Params& consensusParams);