Merge #13429: Return the script type from Solver

984d72ec659361d8c1a6f3c6864e839a807817a7 Return the script type from Solver (Ben Woosley)

Pull request description:

  Because false is synonymous with TX_NONSTANDARD, this conveys the same
  information and makes the handling explicitly based on script type,
  simplifying each call site.

  Prior to this change it was common for the return value to be ignored, or for the
  return value and TX_NONSTANDARD to be redundantly handled.

Tree-SHA512: 31864f856b8cb75f4b782d12678070e8b1cfe9665c6f57cfb25e7ac8bcea8a22f9a78d7c8cf0101c841f2a612400666fb91798bffe88de856e98b873703b0965

4 files changed, 28 insertions, 47 deletions

diff --git a/src/script/ismine.cpp b/src/script/ismine.cpp
index e3a6278c75..1433ebf42f 100644
--- a/src/script/ismine.cpp
+++ b/src/script/ismine.cpp
@@ -60,8 +60,7 @@ IsMineResult IsMineInner(const CKeyStore& keystore, const CScript& scriptPubKey,
     IsMineResult ret = IsMineResult::NO;
 
     std::vector<valtype> vSolutions;
-    txnouttype whichType;
-    Solver(scriptPubKey, whichType, vSolutions);
+    txnouttype whichType = Solver(scriptPubKey, vSolutions);
 
     CKeyID keyID;
     switch (whichType)
diff --git a/src/script/sign.cpp b/src/script/sign.cpp
index 1982e8a832..23af1bd97f 100644
--- a/src/script/sign.cpp
+++ b/src/script/sign.cpp
@@ -101,8 +101,7 @@ static bool SignStep(const SigningProvider& provider, const BaseSignatureCreator
     std::vector<unsigned char> sig;
 
     std::vector<valtype> vSolutions;
-    if (!Solver(scriptPubKey, whichTypeRet, vSolutions))
-        return false;
+    whichTypeRet = Solver(scriptPubKey, vSolutions);
 
     switch (whichTypeRet)
     {
@@ -329,9 +328,8 @@ SignatureData DataFromTransaction(const CMutableTransaction& tx, unsigned int nI
     }
 
     // Get scripts
-    txnouttype script_type;
     std::vector<std::vector<unsigned char>> solutions;
-    Solver(txout.scriptPubKey, script_type, solutions);
+    txnouttype script_type = Solver(txout.scriptPubKey, solutions);
     SigVersion sigversion = SigVersion::BASE;
     CScript next_script = txout.scriptPubKey;
 
@@ -342,7 +340,7 @@ SignatureData DataFromTransaction(const CMutableTransaction& tx, unsigned int nI
         next_script = std::move(redeem_script);
 
         // Get redeemScript type
-        Solver(next_script, script_type, solutions);
+        script_type = Solver(next_script, solutions);
         stack.script.pop_back();
     }
     if (script_type == TX_WITNESS_V0_SCRIPTHASH && !stack.witness.empty() && !stack.witness.back().empty()) {
@@ -352,7 +350,7 @@ SignatureData DataFromTransaction(const CMutableTransaction& tx, unsigned int nI
         next_script = std::move(witness_script);
 
         // Get witnessScript type
-        Solver(next_script, script_type, solutions);
+        script_type = Solver(next_script, solutions);
         stack.witness.pop_back();
         stack.script = std::move(stack.witness);
         stack.witness.clear();
diff --git a/src/script/standard.cpp b/src/script/standard.cpp
index bfbf9f13db..08ba1b1e0f 100644
--- a/src/script/standard.cpp
+++ b/src/script/standard.cpp
@@ -87,7 +87,7 @@ static bool MatchMultisig(const CScript& script, unsigned int& required, std::ve
     return (it + 1 == script.end());
 }
 
-bool Solver(const CScript& scriptPubKey, txnouttype& typeRet, std::vector<std::vector<unsigned char> >& vSolutionsRet)
+txnouttype Solver(const CScript& scriptPubKey, std::vector<std::vector<unsigned char>>& vSolutionsRet)
 {
     vSolutionsRet.clear();
 
@@ -95,33 +95,28 @@ bool Solver(const CScript& scriptPubKey, txnouttype& typeRet, std::vector<std::v
     // it is always OP_HASH160 20 [20 byte hash] OP_EQUAL
     if (scriptPubKey.IsPayToScriptHash())
     {
-        typeRet = TX_SCRIPTHASH;
         std::vector<unsigned char> hashBytes(scriptPubKey.begin()+2, scriptPubKey.begin()+22);
         vSolutionsRet.push_back(hashBytes);
-        return true;
+        return TX_SCRIPTHASH;
     }
 
     int witnessversion;
     std::vector<unsigned char> witnessprogram;
     if (scriptPubKey.IsWitnessProgram(witnessversion, witnessprogram)) {
         if (witnessversion == 0 && witnessprogram.size() == WITNESS_V0_KEYHASH_SIZE) {
-            typeRet = TX_WITNESS_V0_KEYHASH;
             vSolutionsRet.push_back(witnessprogram);
-            return true;
+            return TX_WITNESS_V0_KEYHASH;
         }
         if (witnessversion == 0 && witnessprogram.size() == WITNESS_V0_SCRIPTHASH_SIZE) {
-            typeRet = TX_WITNESS_V0_SCRIPTHASH;
             vSolutionsRet.push_back(witnessprogram);
-            return true;
+            return TX_WITNESS_V0_SCRIPTHASH;
         }
         if (witnessversion != 0) {
-            typeRet = TX_WITNESS_UNKNOWN;
             vSolutionsRet.push_back(std::vector<unsigned char>{(unsigned char)witnessversion});
             vSolutionsRet.push_back(std::move(witnessprogram));
-            return true;
+            return TX_WITNESS_UNKNOWN;
         }
-        typeRet = TX_NONSTANDARD;
-        return false;
+        return TX_NONSTANDARD;
     }
 
     // Provably prunable, data-carrying output
@@ -130,47 +125,39 @@ bool Solver(const CScript& scriptPubKey, txnouttype& typeRet, std::vector<std::v
     // byte passes the IsPushOnly() test we don't care what exactly is in the
     // script.
     if (scriptPubKey.size() >= 1 && scriptPubKey[0] == OP_RETURN && scriptPubKey.IsPushOnly(scriptPubKey.begin()+1)) {
-        typeRet = TX_NULL_DATA;
-        return true;
+        return TX_NULL_DATA;
     }
 
     std::vector<unsigned char> data;
     if (MatchPayToPubkey(scriptPubKey, data)) {
-        typeRet = TX_PUBKEY;
         vSolutionsRet.push_back(std::move(data));
-        return true;
+        return TX_PUBKEY;
     }
 
     if (MatchPayToPubkeyHash(scriptPubKey, data)) {
-        typeRet = TX_PUBKEYHASH;
         vSolutionsRet.push_back(std::move(data));
-        return true;
+        return TX_PUBKEYHASH;
     }
 
     unsigned int required;
     std::vector<std::vector<unsigned char>> keys;
     if (MatchMultisig(scriptPubKey, required, keys)) {
-        typeRet = TX_MULTISIG;
         vSolutionsRet.push_back({static_cast<unsigned char>(required)}); // safe as required is in range 1..16
         vSolutionsRet.insert(vSolutionsRet.end(), keys.begin(), keys.end());
         vSolutionsRet.push_back({static_cast<unsigned char>(keys.size())}); // safe as size is in range 1..16
-        return true;
+        return TX_MULTISIG;
     }
 
     vSolutionsRet.clear();
-    typeRet = TX_NONSTANDARD;
-    return false;
+    return TX_NONSTANDARD;
 }
 
 bool ExtractDestination(const CScript& scriptPubKey, CTxDestination& addressRet)
 {
     std::vector<valtype> vSolutions;
-    txnouttype whichType;
-    if (!Solver(scriptPubKey, whichType, vSolutions))
-        return false;
+    txnouttype whichType = Solver(scriptPubKey, vSolutions);
 
-    if (whichType == TX_PUBKEY)
-    {
+    if (whichType == TX_PUBKEY) {
         CPubKey pubKey(vSolutions[0]);
         if (!pubKey.IsValid())
             return false;
@@ -212,11 +199,11 @@ bool ExtractDestination(const CScript& scriptPubKey, CTxDestination& addressRet)
 bool ExtractDestinations(const CScript& scriptPubKey, txnouttype& typeRet, std::vector<CTxDestination>& addressRet, int& nRequiredRet)
 {
     addressRet.clear();
-    typeRet = TX_NONSTANDARD;
     std::vector<valtype> vSolutions;
-    if (!Solver(scriptPubKey, typeRet, vSolutions))
+    typeRet = Solver(scriptPubKey, vSolutions);
+    if (typeRet == TX_NONSTANDARD) {
         return false;
-    if (typeRet == TX_NULL_DATA){
+    } else if (typeRet == TX_NULL_DATA) {
         // This is data, not addresses
         return false;
     }
@@ -324,14 +311,12 @@ CScript GetScriptForMultisig(int nRequired, const std::vector<CPubKey>& keys)
 
 CScript GetScriptForWitness(const CScript& redeemscript)
 {
-    txnouttype typ;
     std::vector<std::vector<unsigned char> > vSolutions;
-    if (Solver(redeemscript, typ, vSolutions)) {
-        if (typ == TX_PUBKEY) {
-            return GetScriptForDestination(WitnessV0KeyHash(Hash160(vSolutions[0].begin(), vSolutions[0].end())));
-        } else if (typ == TX_PUBKEYHASH) {
-            return GetScriptForDestination(WitnessV0KeyHash(vSolutions[0]));
-        }
+    txnouttype typ = Solver(redeemscript, vSolutions);
+    if (typ == TX_PUBKEY) {
+        return GetScriptForDestination(WitnessV0KeyHash(Hash160(vSolutions[0].begin(), vSolutions[0].end())));
+    } else if (typ == TX_PUBKEYHASH) {
+        return GetScriptForDestination(WitnessV0KeyHash(vSolutions[0]));
     }
     return GetScriptForDestination(WitnessV0ScriptHash(redeemscript));
 }
diff --git a/src/script/standard.h b/src/script/standard.h
index b16ac83e77..fc20fb6a08 100644
--- a/src/script/standard.h
+++ b/src/script/standard.h
@@ -135,11 +135,10 @@ const char* GetTxnOutputType(txnouttype t);
  * script hash, for P2PKH it will contain the key hash, etc.
  *
  * @param[in]   scriptPubKey   Script to parse
- * @param[out]  typeRet        The script type
  * @param[out]  vSolutionsRet  Vector of parsed pubkeys and hashes
- * @return                     True if script matches standard template
+ * @return                     The script type. TX_NONSTANDARD represents a failed solve.
  */
-bool Solver(const CScript& scriptPubKey, txnouttype& typeRet, std::vector<std::vector<unsigned char> >& vSolutionsRet);
+txnouttype Solver(const CScript& scriptPubKey, std::vector<std::vector<unsigned char>>& vSolutionsRet);
 
 /**
  * Parse a standard scriptPubKey for the destination address. Assigns result to