tapfreighter: pre-broadcast guard for split root witnesses

[ffranr]

This PR adds ChainPorter hardening following from this bug: #1897

Add a pre-broadcast verification step to ensure split leaf outputs embed a split root that carries a populated TxWitness, preventing invalid split commitments from being broadcast.

[gemini-code-assist]

Summary of Changes

Hello @ffranr, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request introduces a critical hardening measure to the ChainPorter component by implementing a pre-broadcast verification for split root witnesses. This enhancement ensures that all virtual packets containing split leaf outputs have correctly embedded transaction witnesses within their split roots before being broadcast, thereby preventing the propagation of invalid split commitments and improving the overall integrity and robustness of the system.

Highlights

• Pre-broadcast Verification: A new pre-broadcast verification step has been added to ensure that split leaf outputs embed a split root that carries a populated transaction witness, preventing invalid split commitments from being broadcast.
• Code Refactoring: The existing verifyPacketInputProofs function was refactored to handle a single virtual packet, and a new verifyVPackets function was introduced to orchestrate the verification of multiple packets, including the new split commitment witness check.
• New Verification Function: A new function, verifySplitCommitmentWitnesses, was added to specifically check the validity of witnesses within split commitments.
• Unit Tests: A new unit test, TestVerifySplitCommitmentWitnesses, was added to thoroughly test the new split witness verification logic with various scenarios.

Using Gemini Code Assist

The full guide for Gemini Code Assist can be found on our documentation page, here are some quick tips.

Invoking Gemini

You can request assistance from Gemini at any point by creating a comment using either /gemini <command> or @gemini-code-assist <command>. Below is a summary of the supported commands on the current page.

Feature	Command	Description
Code Review	/gemini review	Performs a code review for the current pull request in its current state.
Pull Request Summary	/gemini summary	Provides a summary of the current pull request in its current state.
Comment	@gemini-code-assist	Responds in comments when explicitly tagged, both in pull request comments and review comments.
Help	/gemini help	Displays a list of available commands.

Customization

To customize Gemini Code Assist for GitHub experience, repository maintainers can create a configuration file and/or provide a custom code review style guide (such as PEP-8 for Python) by creating and adding files to a .gemini/ folder in the base of the repository. Detailed instructions can be found here.

Limitations & Feedback

Gemini Code Assist may make mistakes. Please leave feedback on any instances where its feedback is incorrect or counter productive. You can react with 👍 and 👎 on @gemini-code-assist comments. If you're interested in giving your feedback about your experience with Gemini Code Assist for Github and other Google products, sign up here.

You can also get AI-powered code generation, chat, as well as code reviews directly in the IDE at no cost with the Gemini Code Assist IDE Extension.

Footnotes

1. Review the Privacy Notices, Generative AI Prohibited Use Policy, Terms of Service, and learn how to configure Gemini Code Assist in GitHub here. Gemini can make mistakes, so double check it and use code with caution. ↩

[gemini-code-assist]

Code Review

This pull request introduces a valuable pre-broadcast verification step to ensure that split leaf outputs in Taproot Asset transactions contain a valid witness. This is a solid hardening measure. The changes are well-implemented, including the refactoring of verifyPacketInputProofs for better separation of concerns and the addition of the new verifySplitCommitmentWitnesses function with corresponding tests. My review includes a couple of suggestions to improve code clarity and conciseness by removing a redundant check and using a functional helper for a loop.

[coveralls]

Pull Request Test Coverage Report for Build 20037532411

Details

• 36 of 56 (64.29%) changed or added relevant lines in 1 file are covered.
• 46 unchanged lines in 12 files lost coverage.
• Overall coverage increased (+7.0%) to 56.652%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
tapfreighter/chain_porter.go	36	56	64.29%

Files with Coverage Reduction	New Missed Lines	%
tapdb/mssmt.go	2	91.36%
tapdb/sqlc/mssmt.sql.go	2	48.34%
tapdb/sqlc/transfers.sql.go	2	83.33%
tapdb/sqlc/universe.sql.go	2	73.71%
tapgarden/custodian.go	2	76.83%
tapdb/sqlerrors.go	3	70.71%
universe/archive.go	3	81.05%
mssmt/compacted_tree.go	4	79.03%
universe/syncer.go	4	85.93%
tapdb/multiverse.go	6	79.63%

Totals
Change from base Build 20037487343:	7.0%
Covered Lines:	64924
Relevant Lines:	114601

---

💛 - Coveralls

[jtobin]

LGTM. 👍 👍

[GeorgeTsagk]

Looks good