psbt: support output metadata updates before inputs are added#35797
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l0rinc wants to merge 6 commits into
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psbt: support output metadata updates before inputs are added#35797l0rinc wants to merge 6 commits into
l0rinc wants to merge 6 commits into
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Document the scripts and key origins collected for common output descriptors before changing zero-input handling. Use a valid input for ECDSA-backed outputs because their zero-input paths currently abort.
PSBTv2 permits outputs to be added before inputs, but `UpdatePSBTOutput()` traverses output scripts with a signature creator for input 0. A descriptor with private key material can therefore reach `SignatureHash()` without a corresponding input and abort. Reject the signature attempt while preserving the scripts and key origins collected during traversal.
Add a relative-timelock case that consults the transaction checker during output metadata traversal. Use a valid input because the pre-fix missing-input path is only reliably diagnosed under a sanitizer.
A miniscript relative timelock can consult `CheckSequence()` while `UpdatePSBTOutput()` is only collecting metadata. Return a rejecting checker when the creator has no corresponding input, so traversal can continue without reading a missing sequence.
Document direct Taproot signing with a valid input before covering a missing input index. The PSBT output-update path has no precomputed transaction data, so it cannot exercise this sighash path.
`ComputeSchnorrSignatureHash()` is shared by Schnorr signing and MuSig2 operations and can pass a missing input index to `SignatureHashSchnorr()`. Reject the request before computing the sighash, matching the missing-input behavior for ECDSA signing and transaction checks.
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Problem: PSBTv2 permits outputs to be added before inputs.
An authenticated
descriptorprocesspsbtrequest can abort the node while updating metadata for one of those outputs becauseUpdatePSBTOutput()traverses its script with a signature creator for input 0.ECDSA signing or a miniscript timelock check can then access the missing input.
Fix: Make
MutableTransactionSignatureCreatorreject ECDSA and Schnorr signing and MuSig2 operations when its input index does not exist, and return a rejecting checker for transaction-bound conditions.Output metadata traversal still records scripts and key origins, allowing outputs to be updated before inputs are added.