Merge bitcoin/bitcoin#32129: doc: Update comments for AreInputsStandard to match code

52ede28a8a doc: Update comments for AreInputsStandard to match code (Anthony Towns)

Pull request description:

  The comment about extra data stuffed in scriptSigs was introduced in #4365 which introduced `ScriptSigArgsExpected()`, and became incorrect after #7387 / #7453 (checks are now performed by `SCRIPT_VERIFY_CLEANSTACK` during script validation and `IsPushOnly()` in `IsStandardTx()`). Drops the details on what a p2sh with many checksigs would look like, which was already done in #4365, but only for main.cpp not the duplicated comment in main.h, which was merged into policy/policy.cpp in #6335 and later moved to the right place in #10682.

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merge-script 2025-03-27 15:46:04 +08:00
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@ -169,20 +169,18 @@ bool IsStandardTx(const CTransaction& tx, const std::optional<unsigned>& max_dat
}
/**
* Check transaction inputs to mitigate two
* potential denial-of-service attacks:
* Check transaction inputs.
*
* 1. scriptSigs with extra data stuffed into them,
* not consumed by scriptPubKey (or P2SH script)
* 2. P2SH scripts with a crazy number of expensive
* CHECKSIG/CHECKMULTISIG operations
*
* Why bother? To avoid denial-of-service attacks; an attacker
* can submit a standard HASH... OP_EQUAL transaction,
* which will get accepted into blocks. The redemption
* script can be anything; an attacker could use a very
* expensive-to-check-upon-redemption script like:
* DUP CHECKSIG DROP ... repeated 100 times... OP_1
* This does three things:
* * Prevents mempool acceptance of spends of future
* segwit versions we don't know how to validate
* * Mitigates a potential denial-of-service attack with
* P2SH scripts with a crazy number of expensive
* CHECKSIG/CHECKMULTISIG operations.
* * Prevents spends of unknown/irregular scriptPubKeys,
* which mitigates potential denial-of-service attacks
* involving expensive scripts and helps reserve them
* as potential new upgrade hooks.
*
* Note that only the non-witness portion of the transaction is checked here.
*/