1 files changed, 39 insertions, 35 deletions
diff --git a/src/script/interpreter.cpp b/src/script/interpreter.cpp
index f9716dfc66..ffaba393c0 100644
--- a/src/script/interpreter.cpp
+++ b/src/script/interpreter.cpp
@@ -1,17 +1,16 @@
 // Copyright (c) 2009-2010 Satoshi Nakamoto
-// Copyright (c) 2009-2016 The Bitcoin Core developers
+// Copyright (c) 2009-2017 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
-#include "interpreter.h"
+#include <script/interpreter.h>
 
-#include "primitives/transaction.h"
-#include "crypto/ripemd160.h"
-#include "crypto/sha1.h"
-#include "crypto/sha256.h"
-#include "pubkey.h"
-#include "script/script.h"
-#include "uint256.h"
+#include <crypto/ripemd160.h>
+#include <crypto/sha1.h>
+#include <crypto/sha256.h>
+#include <pubkey.h>
+#include <script/script.h>
+#include <uint256.h>
 
 typedef std::vector<unsigned char> valtype;
 
@@ -111,7 +110,7 @@ bool static IsValidSignatureEncoding(const std::vector<unsigned char> &sig) {
     //   excluding the sighash byte.
     // * R-length: 1-byte length descriptor of the R value that follows.
     // * R: arbitrary-length big-endian encoded R value. It must use the shortest
-    //   possible encoding for a positive integers (which means no null bytes at
+    //   possible encoding for a positive integer (which means no null bytes at
     //   the start, except a single one when the next byte has its highest bit set).
     // * S-length: 1-byte length descriptor of the S value that follows.
     // * S: arbitrary-length big-endian encoded S value. The same rules apply.
@@ -174,7 +173,13 @@ bool static IsLowDERSignature(const valtype &vchSig, ScriptError* serror) {
     if (!IsValidSignatureEncoding(vchSig)) {
         return set_error(serror, SCRIPT_ERR_SIG_DER);
     }
+    // https://bitcoin.stackexchange.com/a/12556:
+    //     Also note that inside transaction signatures, an extra hashtype byte
+    //     follows the actual signature data.
     std::vector<unsigned char> vchSigCopy(vchSig.begin(), vchSig.begin() + vchSig.size() - 1);
+    // If the S value is above the order of the curve divided by two, its
+    // complement modulo the order could have been used instead, which is
+    // one byte shorter when encoded correctly.
     if (!CPubKey::CheckLowS(vchSigCopy)) {
         return set_error(serror, SCRIPT_ERR_SIG_HIGH_S);
     }
@@ -221,23 +226,25 @@ bool static CheckPubKeyEncoding(const valtype &vchPubKey, unsigned int flags, co
 }
 
 bool static CheckMinimalPush(const valtype& data, opcodetype opcode) {
+    // Excludes OP_1NEGATE, OP_1-16 since they are by definition minimal
+    assert(0 <= opcode && opcode <= OP_PUSHDATA4);
     if (data.size() == 0) {
-        // Could have used OP_0.
+        // Should have used OP_0.
         return opcode == OP_0;
     } else if (data.size() == 1 && data[0] >= 1 && data[0] <= 16) {
-        // Could have used OP_1 .. OP_16.
-        return opcode == OP_1 + (data[0] - 1);
+        // Should have used OP_1 .. OP_16.
+        return false;
     } else if (data.size() == 1 && data[0] == 0x81) {
-        // Could have used OP_1NEGATE.
-        return opcode == OP_1NEGATE;
+        // Should have used OP_1NEGATE.
+        return false;
     } else if (data.size() <= 75) {
-        // Could have used a direct push (opcode indicating number of bytes pushed + those bytes).
+        // Must have used a direct push (opcode indicating number of bytes pushed + those bytes).
         return opcode == data.size();
     } else if (data.size() <= 255) {
-        // Could have used OP_PUSHDATA.
+        // Must have used OP_PUSHDATA.
         return opcode == OP_PUSHDATA1;
     } else if (data.size() <= 65535) {
-        // Could have used OP_PUSHDATA2.
+        // Must have used OP_PUSHDATA2.
         return opcode == OP_PUSHDATA2;
     }
     return true;
@@ -349,9 +356,6 @@ bool EvalScript(std::vector<std::vector<unsigned char> >& stack, const CScript&
                 {
                     if (!(flags & SCRIPT_VERIFY_CHECKLOCKTIMEVERIFY)) {
                         // not enabled; treat as a NOP2
-                        if (flags & SCRIPT_VERIFY_DISCOURAGE_UPGRADABLE_NOPS) {
-                            return set_error(serror, SCRIPT_ERR_DISCOURAGE_UPGRADABLE_NOPS);
-                        }
                         break;
                     }
 
@@ -391,9 +395,6 @@ bool EvalScript(std::vector<std::vector<unsigned char> >& stack, const CScript&
                 {
                     if (!(flags & SCRIPT_VERIFY_CHECKSEQUENCEVERIFY)) {
                         // not enabled; treat as a NOP3
-                        if (flags & SCRIPT_VERIFY_DISCOURAGE_UPGRADABLE_NOPS) {
-                            return set_error(serror, SCRIPT_ERR_DISCOURAGE_UPGRADABLE_NOPS);
-                        }
                         break;
                     }
 
@@ -1168,29 +1169,36 @@ uint256 GetOutputsHash(const CTransaction& txTo) {
 
 PrecomputedTransactionData::PrecomputedTransactionData(const CTransaction& txTo)
 {
-    hashPrevouts = GetPrevoutHash(txTo);
-    hashSequence = GetSequenceHash(txTo);
-    hashOutputs = GetOutputsHash(txTo);
+    // Cache is calculated only for transactions with witness
+    if (txTo.HasWitness()) {
+        hashPrevouts = GetPrevoutHash(txTo);
+        hashSequence = GetSequenceHash(txTo);
+        hashOutputs = GetOutputsHash(txTo);
+        ready = true;
+    }
 }
 
 uint256 SignatureHash(const CScript& scriptCode, const CTransaction& txTo, unsigned int nIn, int nHashType, const CAmount& amount, SigVersion sigversion, const PrecomputedTransactionData* cache)
 {
+    assert(nIn < txTo.vin.size());
+
     if (sigversion == SIGVERSION_WITNESS_V0) {
         uint256 hashPrevouts;
         uint256 hashSequence;
         uint256 hashOutputs;
+        const bool cacheready = cache && cache->ready;
 
         if (!(nHashType & SIGHASH_ANYONECANPAY)) {
-            hashPrevouts = cache ? cache->hashPrevouts : GetPrevoutHash(txTo);
+            hashPrevouts = cacheready ? cache->hashPrevouts : GetPrevoutHash(txTo);
         }
 
         if (!(nHashType & SIGHASH_ANYONECANPAY) && (nHashType & 0x1f) != SIGHASH_SINGLE && (nHashType & 0x1f) != SIGHASH_NONE) {
-            hashSequence = cache ? cache->hashSequence : GetSequenceHash(txTo);
+            hashSequence = cacheready ? cache->hashSequence : GetSequenceHash(txTo);
         }
 
 
         if ((nHashType & 0x1f) != SIGHASH_SINGLE && (nHashType & 0x1f) != SIGHASH_NONE) {
-            hashOutputs = cache ? cache->hashOutputs : GetOutputsHash(txTo);
+            hashOutputs = cacheready ? cache->hashOutputs : GetOutputsHash(txTo);
         } else if ((nHashType & 0x1f) == SIGHASH_SINGLE && nIn < txTo.vout.size()) {
             CHashWriter ss(SER_GETHASH, 0);
             ss << txTo.vout[nIn];
@@ -1221,10 +1229,6 @@ uint256 SignatureHash(const CScript& scriptCode, const CTransaction& txTo, unsig
     }
 
     static const uint256 one(uint256S("0000000000000000000000000000000000000000000000000000000000000001"));
-    if (nIn >= txTo.vin.size()) {
-        //  nIn out of range
-        return one;
-    }
 
     // Check for invalid use of SIGHASH_SINGLE
     if ((nHashType & 0x1f) == SIGHASH_SINGLE) {
@@ -1366,7 +1370,7 @@ static bool VerifyWitnessProgram(const CScriptWitness& witness, int witversion,
             stack = std::vector<std::vector<unsigned char> >(witness.stack.begin(), witness.stack.end() - 1);
             uint256 hashScriptPubKey;
             CSHA256().Write(&scriptPubKey[0], scriptPubKey.size()).Finalize(hashScriptPubKey.begin());
-            if (memcmp(hashScriptPubKey.begin(), &program[0], 32)) {
+            if (memcmp(hashScriptPubKey.begin(), program.data(), 32)) {
                 return set_error(serror, SCRIPT_ERR_WITNESS_PROGRAM_MISMATCH);
             }
         } else if (program.size() == 20) {