fix(wasm-utxo): infer input script type in fromPsbt with nonstandard derivations - #361
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…erivations Dimensions.fromPsbt classifies inputs using BIP32 derivation chain codes, falling back to P2shP2pk when no standard BitGo chain is found. PSBTs with nonstandard chain codes on valid P2WSH 2-of-3 multisig inputs cause misclassification as non-segwit P2shP2pk. This inflates vsize ~2.5x, understates feeRate, and triggers maxfeerate broadcast rejections (WCN-2155). This test asserts the current (buggy) behavior: a P2WSH PSBT built with nonstandard chain codes (0/1 instead of 20/21) via the WrapPsbt/descriptor API is classified as non-segwit P2shP2pk, producing a larger vsize than the equivalent wallet-built PSBT. Also asserts the P2shP2pk fallback for replay-protection inputs without derivations. Refs: WCN-2155
…ard derivations Dimensions.from_psbt unconditionally classified inputs lacking BIP32 derivation paths as P2shP2pk (replay protection), regardless of the actual script type. For P2WSH PSBTs with nonstandard derivation paths this inflated vsize ~2.5x, understating feeRate and triggering maxfeerate broadcast rejections (WCN-2155). Replace the entire classification path with a single call to infer_input_script_type for every input. Classification is now based solely on script metadata: witness_script (verified as 2-of-3 multisig via parse_multisig_script_2_of_3) → P2wsh/P2shP2wsh; redeem_script (P2PK via parse_p2pk_script, or 2-of-3 multisig) → P2shP2pk/P2sh; taproot metadata (tap_scripts/tap_internal_key) → P2trMusig2 variants; is_p2mr output → P2mr. Every candidate is cross-checked against the output-script shape; mismatches and bare inputs (only witness_utxo) error rather than guessing. The old BIP32 derivation-chain-code path is removed entirely — script metadata is sufficient and more authoritative. The P2shP2pk default fallback is gone; replay protection inputs are now correctly detected via their P2PK redeem_script. Refs: WCN-2155
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Summary
Dimensions.from_psbtclassified inputs based on BIP32 derivation chain codes, falling back toP2shP2pk(replay protection) when no standard BitGo chain was found. For P2WSH PSBTs with nonstandard derivation paths this inflated vsize ~2.5x, understatingfeeRate, triggeringmaxfeeratebroadcast rejections (WCN-2155).Replace the entire classification path with a single call to
infer_input_script_typefor every input. Classification is now based solely on script metadata (witness_script, redeem_script, taproot fields, output-script shape), independent of BIP32 derivation chain codes.Changes
psbt_wallet_input.rs— Addinfer_input_script_type, which classifies from script/witness metadata: witness_script (verified as 2-of-3 multisig) → P2wsh/P2shP2wsh; redeem_script (P2PK or 2-of-3 multisig) → P2shP2pk/P2sh; taproot metadata → P2trMusig2 variants; is_p2mr output → P2mr. Every candidate is cross-checked against the output-script shape. Errors on bare inputs (only witness_utxo) or shape mismatches.dimensions.rs— Replace the entirefrom_psbtinput classification loop with a call toinfer_input_script_type. The old BIP32 derivation-chain-code path and P2shP2pk default fallback are removed.address/mod.rs— Re-exportis_p2mraspub(crate)for P2MR (BIP-360) detection.test/dimensions.ts— Red test (commit 1) reproduces the bug with nonstandard derivation paths via the WrapPsbt/descriptor API; fix commit flips assertions to green and adds a replay-protection test case.Refs: WCN-2155