From b6e03cc59208305681745ad06f2056ffe6690597 Mon Sep 17 00:00:00 2001 From: Pieter Wuille Date: Sun, 12 Oct 2014 18:39:47 -0700 Subject: Add SCRIPT_VERIFY_CLEANSTACK (BIP62 rule 6) Based on an earlier patch by Peter Todd, though the rules here are different (P2SH scripts should not have a CLEANSTACK check before the P2SH evaluation). --- src/script/interpreter.cpp | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) (limited to 'src/script/interpreter.cpp') diff --git a/src/script/interpreter.cpp b/src/script/interpreter.cpp index d97f917c37..1b187f5ef5 100644 --- a/src/script/interpreter.cpp +++ b/src/script/interpreter.cpp @@ -1096,7 +1096,6 @@ 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); @@ -1126,8 +1125,18 @@ bool VerifyScript(const CScript& scriptSig, const CScript& scriptPubKey, unsigne return set_error(serror, SCRIPT_ERR_EVAL_FALSE); 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); -- cgit v1.2.3