Aave Improvement Proposals (AIPs) describe standards for the Aave Protocol, including core protocol specifications, client APIs, and contract standards.

AIP 28: Polygon Cross-chain Governance Test

Author: Steven Valeri Status: Proposed - Discussions- RawCreated: July 30, 2021

Simple Summary

The intention of this AIP is to test a cross-chain transaction workflow that would enable the Ethereum based smart contract for governance for the Aave Protocol (the “Aave Ethereum Governance”) to control the deployment of the Aave Protocol on Polygon (the “Aave Polygon market”). The proposal is written as a transaction that would make updates to a mock Aave Polygon market. If approved, the transaction would trigger a cross-chain message, flowing from Aave’s Ethereum Governance, to a new contract - the PolygonBridgeExecutor. The PolygonBridgeExecutor would store the proposed market updates for a delay window, and then allow for the updates to be executed on the mock Aave Polygon market.

This proposal will allow testing the end-to-end crosschain transaction workflow for Polygon market governance using both the Ethereum and Polygon mainnet contracts in a way that cannot be replicated in another manner. This test will support the case in the future to transfer ownership of the Aave Polygon Market to Aave’s Ethereum governance.

In-Scope: A test of the governance cross-chain bridge functionality on a mock Aave Polygon market.

Out-of-Scope: Transferring ownership of the Aave Polygon Market to the Aave Ethereum Governance

Abstract

Test an implementation of a cross-chain governance workflow, allowing Aave’s Ethereum Governance to execute a transaction updating a mock Aave market deployed on Polygon.

Motivation

Before anyone in the community or otherwise can make a proposal to transfer ownership of the Aave Polygon market to a cross-chain bridge workflow, it is necessary that any smart contracts be tested as thoroughly as possible. This AIP is a real world test using the Aave Ethereum Governance contract to test the cross-chain bridge contracts on a mock Aave Polygon Market. The main reasons for testing to this extent are:

  • Cross-chain / bridge transactions are relatively new and complex
  • The risk of this workflow being deployed and not operating correctly would have a HIGH impact

The transfer of ownership of the Aave Polygon Market to Aave’s Ethereum Governance is not in-scope of this AIP, but understanding the motivation behind that desired change is important to understanding the motivation for this test.

The current owner of the Aave Polygon Market a multi-sig wallet due to the time needed to build a cross-chain governance platform, as well as ensuring security for a new deployment on a new network.

Given the overarching goal that any deployment of the Aave Protocol be owned by decentralized governance, transferring ownership of the Aave Polygon market contracts to Aave Ethereum Governance, is an important next step. Additionally, we have developed and deployed a cross-chain governance platform aimed at providing a broad solution for cross-chain governance. After appropriate testing (including this AIP) and auditing of the cross-chain bridge contract, anyone can create a future AIP to remove the multi-sig over the Aave Polygon market and transfer ownership of those smart contracts to Aave Ethereum Governance.

Specification

A detailed specification of the crosschain-bridge contract and workflow is outlined in the repo here

https://github.com/Aave/governance-crosschain-bridges

For this test specifically, the test would flow from Aave Ethereum Governance, through a cross chain transaction to the PolygonBridgeExecutor contract. Then after a delay, the proposal would be executed on Polygon to make updates to the mock Aave Polygon market.

The general flow of this test will be

  1. Propose cross-chain test transactions (Aave governance-v2)
  2. Vote on cross-chain test transactions (Aave governance-v2)
  3. Queue test transactions
  4. Execute cross-chain test transactions
    4a. Execute transaction from Aave Governance (Aave governance-v2)
    4b. Bridge the test transactions to Polygon (Polygon fxPortal and Polygon Inherent Bridge Functionality)
    4c. Receive bridged message on Polygon (Polygon fxPortal and Polygon Inherent Bridge Functionality)
    4d. Queue transactions for execution in PolygonBridgeExecutor (Aave governance-crosschain-bridges)\
  5. Wait for delay
  6. Execute queued transactions in the PolygonBridgeExecutor (Aave governance-crosschain-bridges)
    6a. Turn off borrowing for the mock Dai reserve
    6b. Transfer POOL_ADMIN rights to a dummy address
    6c. Transfer ownership of the mock Aave market to a dummy address\
  7. Confirm the expected updates have been made on mock Aave market

Rationale

This AIP will not make any actual changes in the current Aave Polygon market ecosystem or in any other deployment of the Aave Protocol. It is merely a test of a contract and workflow that, in the future, could enable the Aave Ethereum Governance to control the Aave Polygon Market.

Testing the contracts that enable this cross-chain bridging as thoroughly as possible, including via this proposed test are rationale, despite their cost, given the critical role the cross-chain bridging will play if deployed and used for cross-chain governance.

Test Cases

A full suit of tests with 100% coverage is included in the repo https://github.com/Aave/governance-crosschain-bridges. The cross-chain workflow has also successfully been tested on the Goerli-Mumbai test networks.

Implementation

A mock implementation of this proposed test can be found here:

https://github.com/Aave/governance-crosschain-bridges/tree/feat/mainnet-test

After setting up the repository:

npm run hardhat mock-mainnet-proposal-delegate runs on Ethereum fork to makes sure everything is encoded correctly to be submitted for the proposal

npm run hardhat mock-Polygon-test-delegate set a .env variable Polygon_FORK = "true" to run the test updating the Polygon market via the mainnet PolygonBridgeExecutor on a Polygon fork

Two helper contracts have been deployed to support this proposal. PolygonMessageSender has been deployed on Ethereum and PolygonMarketUpdate has been deployed on Polygon.

This proposal, if executed, calls the function sendMessage() on the PolygonMessageSender contract on Ethereum mainnet via a delegatecall. The sendMessage function encodes a delegatecall to the function executeUpate() on the contract MarketUpdate deployed on the Polygon network and then sends that encoded action to the PolygonBridgeExecutor on the Polygon network via Polygon’s FxPortal. When that action is received in the PolygonBridgeExecutor, it will be queued. After a delay, that action can be executed, calling the function executeUpate() which will make three updates to a mock aave market deployed on Polygon:

  1. disable the mock dai reserve via the LendingPoolConfigurator contract
  2. Set the pool admin to the address 0x000000000000000000000000000000000000dEaD via the LendingPoolAddressesProvider contract
  3. Transfer ownership of the pool to the address 0x0000000000000000000000000000000000000001 via the LendingPoolAddressesProvider contract

Related Contracts:

Ethereum PolygonMessageSender Contract PolygonMessageSender: 0xf442C0faE2E9A157cD0202BD63bf9b932D3aa4C8
https://etherscan.io/address/0xf442C0faE2E9A157cD0202BD63bf9b932D3aa4C8#code \

Polygon FxPortal Bridge Contracts
FxRoot: 0xfe5e5D361b2ad62c541bAb87C45a0B9B018389a2
https://etherscan.io/address/0xfe5e5D361b2ad62c541bAb87C45a0B9B018389a2#code
StateSender: 0x28e4F3a7f651294B9564800b2D01f35189A5bFbE
https://etherscan.io/address/0x28e4f3a7f651294b9564800b2d01f35189a5bfbe#code
FxChild: 0x8397259c983751DAf40400790063935a11afa28a
https://polygonscan.com/address/0x8397259c983751DAf40400790063935a11afa28a#code

Polygon Bridge Executor Contracts
PolygonBridgeExecutor: 0x60966EA42764c7c538Af9763Bc11860eB2556E6B
https://polygonscan.com/address/0xd63b6b5e0f043e9779c784ee1c14ffcbffb98b70#code

Polygon Market Update
MarketUpdate: 0x5b494b94faf0bb63254dba26f17483bcf57f6d6a
https://polygonscan.com/address/0x5b494b94faf0bb63254dba26f17483bcf57f6d6a#code

Mock Polygon Market Contracts
LendingPoolAddressProviderAddress = 0x240de965908e06a76e1937310627b709b5045bd6
https://polygonscan.com/address/0x240de965908e06a76e1937310627b709b5045bd6#code
LendingPoolConfiguratorAddress (proxy)= 0xd63B6B5E0F043e9779C784Ee1c14fFcBffB98b70
https://polygonscan.com/address/0xd63b6b5e0f043e9779c784ee1c14ffcbffb98b70#writeContract#code
LendingPoolConfiguratorAddress (implementation)= 0xADA061366575324945c7a097F829349acA6C9aB9
https://polygonscan.com/address/0xADA061366575324945c7a097F829349acA6C9aB9#code

Copyright

Copyright and related rights waived via CC0.

Aave Improvement Proposals (AIPs) describe standards for the Aave Protocol, including core protocol specifications, client APIs, and contract standards.

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