From 3450a9b25cd6dbc69daf946bd3a610681ee61317 Mon Sep 17 00:00:00 2001
From: Ben Woosley <ben.woosley@gmail.com>
Date: Tue, 10 Apr 2018 20:13:32 -0700
Subject: [PATCH] Extract consts for WITNESS_V0 hash sizes

---
 src/policy/policy.cpp      | 2 +-
 src/script/interpreter.cpp | 8 ++++----
 src/script/interpreter.h   | 4 ++++
 src/script/standard.cpp    | 4 ++--
 4 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/src/policy/policy.cpp b/src/policy/policy.cpp
index c3f65fb2ab..5963bf371a 100644
--- a/src/policy/policy.cpp
+++ b/src/policy/policy.cpp
@@ -230,7 +230,7 @@ bool IsWitnessStandard(const CTransaction& tx, const CCoinsViewCache& mapInputs)
             return false;
 
         // Check P2WSH standard limits
-        if (witnessversion == 0 && witnessprogram.size() == 32) {
+        if (witnessversion == 0 && witnessprogram.size() == WITNESS_V0_SCRIPTHASH_SIZE) {
             if (tx.vin[i].scriptWitness.stack.back().size() > MAX_STANDARD_P2WSH_SCRIPT_SIZE)
                 return false;
             size_t sizeWitnessStack = tx.vin[i].scriptWitness.stack.size() - 1;
diff --git a/src/script/interpreter.cpp b/src/script/interpreter.cpp
index 182f4a3327..338e07e24e 100644
--- a/src/script/interpreter.cpp
+++ b/src/script/interpreter.cpp
@@ -1361,7 +1361,7 @@ static bool VerifyWitnessProgram(const CScriptWitness& witness, int witversion,
     CScript scriptPubKey;
 
     if (witversion == 0) {
-        if (program.size() == 32) {
+        if (program.size() == WITNESS_V0_SCRIPTHASH_SIZE) {
             // Version 0 segregated witness program: SHA256(CScript) inside the program, CScript + inputs in witness
             if (witness.stack.size() == 0) {
                 return set_error(serror, SCRIPT_ERR_WITNESS_PROGRAM_WITNESS_EMPTY);
@@ -1373,7 +1373,7 @@ static bool VerifyWitnessProgram(const CScriptWitness& witness, int witversion,
             if (memcmp(hashScriptPubKey.begin(), program.data(), 32)) {
                 return set_error(serror, SCRIPT_ERR_WITNESS_PROGRAM_MISMATCH);
             }
-        } else if (program.size() == 20) {
+        } else if (program.size() == WITNESS_V0_KEYHASH_SIZE) {
             // Special case for pay-to-pubkeyhash; signature + pubkey in witness
             if (witness.stack.size() != 2) {
                 return set_error(serror, SCRIPT_ERR_WITNESS_PROGRAM_MISMATCH); // 2 items in witness
@@ -1530,10 +1530,10 @@ bool VerifyScript(const CScript& scriptSig, const CScript& scriptPubKey, const C
 size_t static WitnessSigOps(int witversion, const std::vector<unsigned char>& witprogram, const CScriptWitness& witness, int flags)
 {
     if (witversion == 0) {
-        if (witprogram.size() == 20)
+        if (witprogram.size() == WITNESS_V0_KEYHASH_SIZE)
             return 1;
 
-        if (witprogram.size() == 32 && witness.stack.size() > 0) {
+        if (witprogram.size() == WITNESS_V0_SCRIPTHASH_SIZE && witness.stack.size() > 0) {
             CScript subscript(witness.stack.back().begin(), witness.stack.back().end());
             return subscript.GetSigOpCount(true);
         }
diff --git a/src/script/interpreter.h b/src/script/interpreter.h
index bb7750d783..601a4a866d 100644
--- a/src/script/interpreter.h
+++ b/src/script/interpreter.h
@@ -129,6 +129,10 @@ enum class SigVersion
     WITNESS_V0 = 1,
 };
 
+/** Signature hash sizes */
+static constexpr size_t WITNESS_V0_SCRIPTHASH_SIZE = 32;
+static constexpr size_t WITNESS_V0_KEYHASH_SIZE = 20;
+
 uint256 SignatureHash(const CScript &scriptCode, const CTransaction& txTo, unsigned int nIn, int nHashType, const CAmount& amount, SigVersion sigversion, const PrecomputedTransactionData* cache = nullptr);
 
 class BaseSignatureChecker
diff --git a/src/script/standard.cpp b/src/script/standard.cpp
index 0b9053d7fc..76778112aa 100644
--- a/src/script/standard.cpp
+++ b/src/script/standard.cpp
@@ -66,12 +66,12 @@ bool Solver(const CScript& scriptPubKey, txnouttype& typeRet, std::vector<std::v
     int witnessversion;
     std::vector<unsigned char> witnessprogram;
     if (scriptPubKey.IsWitnessProgram(witnessversion, witnessprogram)) {
-        if (witnessversion == 0 && witnessprogram.size() == 20) {
+        if (witnessversion == 0 && witnessprogram.size() == WITNESS_V0_KEYHASH_SIZE) {
             typeRet = TX_WITNESS_V0_KEYHASH;
             vSolutionsRet.push_back(witnessprogram);
             return true;
         }
-        if (witnessversion == 0 && witnessprogram.size() == 32) {
+        if (witnessversion == 0 && witnessprogram.size() == WITNESS_V0_SCRIPTHASH_SIZE) {
             typeRet = TX_WITNESS_V0_SCRIPTHASH;
             vSolutionsRet.push_back(witnessprogram);
             return true;