Runtime BTC Knots policy changes

Inspiration

Updating mempool transaction policy requires a full rebuild of the bitcoin client, which:

• Presents a challenge to less technical users
• Slows iteration time for testing/adjusting policy changes
• Centralizes policy acceptance
• Prevents sharing custom policies between users
• Decreases visibility of policies currently in effect

By removing this rebuild limitation, we address these challenges (and potentially many more)!

What it does

• During runtime, evaluates zero or more lua scripts when determining whether (or not) to accept a given transaction into the node's mempool

How we built it

• Install bitcoinknots/bitcoin dependencies
• Install lua
• Add references to sol2
• Evaluate script(s) within IsStandardTx (policy.cpp)

Challenges we ran into

• Not familiar with project's build scripts -> lengthy time to get dependencies added and working
• Had to work around issue with Clang_IndVarSimplify_Bug_SanityCheck

What's next for Runtime BTC Knots policy changes

• Pass transaction details and configuration options to lua script
• Add configuration to enable/disable this functionality
• Curate collection of useful scripts for users to opt-in (by downloading & placing in the scripts directory)

Built With

• knots
• lua