diff options
Diffstat (limited to 'src/script')
| -rw-r--r-- | src/script/interpreter.cpp | 32 | ||||
| -rw-r--r-- | src/script/interpreter.h | 10 | ||||
| -rw-r--r-- | src/script/script_error.h | 1 | ||||
| -rw-r--r-- | src/script/standard.h | 3 |
4 files changed, 33 insertions, 13 deletions
diff --git a/src/script/interpreter.cpp b/src/script/interpreter.cpp index e979f61f6e..d0f75ab672 100644 --- a/src/script/interpreter.cpp +++ b/src/script/interpreter.cpp @@ -1098,7 +1098,6 @@ bool VerifyScript(const CScript& scriptSig, const CScript& scriptPubKey, unsigne return false; if (stack.empty()) return set_error(serror, SCRIPT_ERR_EVAL_FALSE); - if (CastToBool(stack.back()) == false) return set_error(serror, SCRIPT_ERR_EVAL_FALSE); @@ -1109,24 +1108,37 @@ bool VerifyScript(const CScript& scriptSig, const CScript& scriptPubKey, unsigne if (!scriptSig.IsPushOnly()) return set_error(serror, SCRIPT_ERR_SIG_PUSHONLY); - // stackCopy cannot be empty here, because if it was the + // Restore stack. + swap(stack, stackCopy); + + // stack cannot be empty here, because if it was the // P2SH HASH <> EQUAL scriptPubKey would be evaluated with // an empty stack and the EvalScript above would return false. - assert(!stackCopy.empty()); + assert(!stack.empty()); - const valtype& pubKeySerialized = stackCopy.back(); + const valtype& pubKeySerialized = stack.back(); CScript pubKey2(pubKeySerialized.begin(), pubKeySerialized.end()); - popstack(stackCopy); + popstack(stack); - if (!EvalScript(stackCopy, pubKey2, flags, checker, serror)) + if (!EvalScript(stack, pubKey2, flags, checker, serror)) // serror is set return false; - if (stackCopy.empty()) + if (stack.empty()) return set_error(serror, SCRIPT_ERR_EVAL_FALSE); - if (!CastToBool(stackCopy.back())) + if (!CastToBool(stack.back())) return set_error(serror, SCRIPT_ERR_EVAL_FALSE); - else - return set_success(serror); + } + + // The CLEANSTACK check is only performed after potential P2SH evaluation, + // as the non-P2SH evaluation of a P2SH script will obviously not result in + // a clean stack (the P2SH inputs remain). + if ((flags & SCRIPT_VERIFY_CLEANSTACK) != 0) { + // Disallow CLEANSTACK without P2SH, as otherwise a switch CLEANSTACK->P2SH+CLEANSTACK + // would be possible, which is not a softfork (and P2SH should be one). + assert((flags & SCRIPT_VERIFY_P2SH) != 0); + if (stack.size() != 1) { + return set_error(serror, SCRIPT_ERR_CLEANSTACK); + } } return set_success(serror); diff --git a/src/script/interpreter.h b/src/script/interpreter.h index 3c4e7d466a..8bf379ed89 100644 --- a/src/script/interpreter.h +++ b/src/script/interpreter.h @@ -67,8 +67,14 @@ enum // discouraged NOPs fails the script. This verification flag will never be // a mandatory flag applied to scripts in a block. NOPs that are not // executed, e.g. within an unexecuted IF ENDIF block, are *not* rejected. - SCRIPT_VERIFY_DISCOURAGE_UPGRADABLE_NOPS = (1U << 7) - + SCRIPT_VERIFY_DISCOURAGE_UPGRADABLE_NOPS = (1U << 7), + + // Require that only a single stack element remains after evaluation. This changes the success criterion from + // "At least one stack element must remain, and when interpreted as a boolean, it must be true" to + // "Exactly one stack element must remain, and when interpreted as a boolean, it must be true". + // (softfork safe, BIP62 rule 6) + // Note: CLEANSTACK should never be used without P2SH. + SCRIPT_VERIFY_CLEANSTACK = (1U << 8), }; uint256 SignatureHash(const CScript &scriptCode, const CTransaction& txTo, unsigned int nIn, int nHashType); diff --git a/src/script/script_error.h b/src/script/script_error.h index 5c260327b6..6365680b29 100644 --- a/src/script/script_error.h +++ b/src/script/script_error.h @@ -43,6 +43,7 @@ typedef enum ScriptError_t SCRIPT_ERR_SIG_HIGH_S, SCRIPT_ERR_SIG_NULLDUMMY, SCRIPT_ERR_PUBKEYTYPE, + SCRIPT_ERR_CLEANSTACK, /* softfork safeness */ SCRIPT_ERR_DISCOURAGE_UPGRADABLE_NOPS, diff --git a/src/script/standard.h b/src/script/standard.h index dbeeace4d9..ac80193773 100644 --- a/src/script/standard.h +++ b/src/script/standard.h @@ -48,7 +48,8 @@ static const unsigned int STANDARD_SCRIPT_VERIFY_FLAGS = MANDATORY_SCRIPT_VERIFY SCRIPT_VERIFY_STRICTENC | SCRIPT_VERIFY_MINIMALDATA | SCRIPT_VERIFY_NULLDUMMY | - SCRIPT_VERIFY_DISCOURAGE_UPGRADABLE_NOPS; + SCRIPT_VERIFY_DISCOURAGE_UPGRADABLE_NOPS | + SCRIPT_VERIFY_CLEANSTACK; /** For convenience, standard but not mandatory verify flags. */ static const unsigned int STANDARD_NOT_MANDATORY_VERIFY_FLAGS = STANDARD_SCRIPT_VERIFY_FLAGS & ~MANDATORY_SCRIPT_VERIFY_FLAGS; |