diff --git a/src/validation.cpp b/src/validation.cpp index 4184d5a81..a9cf42501 100644 --- a/src/validation.cpp +++ b/src/validation.cpp @@ -1410,21 +1410,25 @@ bool CheckInputs(const CTransaction& tx, CValidationState &state, const CCoinsVi // Check whether the failure was caused by a // non-mandatory script verification check, such as // non-standard DER encodings or non-null dummy - // arguments; if so, don't trigger DoS protection to - // avoid splitting the network between upgraded and - // non-upgraded nodes. + // arguments; if so, ensure we return NOT_STANDARD + // instead of CONSENSUS to avoid downstream users + // splitting the network between upgraded and + // non-upgraded nodes by banning CONSENSUS-failing + // data providers. CScriptCheck check2(coin.out, tx, i, flags & ~STANDARD_NOT_MANDATORY_VERIFY_FLAGS, cacheSigStore, &txdata); if (check2()) return state.Invalid(ValidationInvalidReason::TX_NOT_STANDARD, false, REJECT_NONSTANDARD, strprintf("non-mandatory-script-verify-flag (%s)", ScriptErrorString(check.GetScriptError()))); } - // Failures of other flags indicate a transaction that is - // invalid in new blocks, e.g. an invalid P2SH. We DoS ban - // such nodes as they are not following the protocol. That - // said during an upgrade careful thought should be taken - // as to the correct behavior - we may want to continue - // peering with non-upgraded nodes even after soft-fork - // super-majority signaling has occurred. + // MANDATORY flag failures correspond to + // ValidationInvalidReason::CONSENSUS. Because CONSENSUS + // failures are the most serious case of validation + // failures, we may need to consider using + // RECENT_CONSENSUS_CHANGE for any script failure that + // could be due to non-upgraded nodes which we may want to + // support, to avoid splitting the network (but this + // depends on the details of how net_processing handles + // such errors). return state.Invalid(ValidationInvalidReason::CONSENSUS, false, REJECT_INVALID, strprintf("mandatory-script-verify-flag-failed (%s)", ScriptErrorString(check.GetScriptError()))); } }