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cow-shed

cow-shed

COWShed is a user owned ERC1967 proxy deployed at a determininstic address using create2 with the user address as the salt.

This deterministic deployment allows users to set the proxy address as the receiver for cowswap orders with pre/post hooks. At the first execution of hooks, the proxy gets deployed for the user and the hooks are executed.

User signs a EIP712 message for the pre/post hooks which gets validated and only user signed hooks are executed on the user's proxy. This allows users to confidently perform permissioned actions in the hooks like:

  1. transferring assets from the proxy to someone else.
  2. use the proxy to add collateral or repay debt on a maker CDP or a aave debt position, etc.

The signed message type looks like:

ExecuteHooks(Call[] calls,bytes32 nonce,uint256 deadline)
Call(address target,uint256 value,bytes callData,bool allowFailure,bool isDelegateCall)

The EOA signatures are expected to be 65 bytes long and to be encoded as abi.encodePacked(r, s, v).

Nonces are used to ensure signed hooks are only executed once and they also allow users to revoke the signed hooks in case they want to. And users must manage them.

The nonces are not constrained to be sequential, so multiple orders with hooks can be executed out of order, but still validated. However, nonces are implemented using a bitmap. And sequential nonces will save some gas.

The system also support smart contracts. In case of contracts, EIP1271 signatures are used to authenticate the signed hooks.

The factory also implements an ENS forward and reverse resolver. When the factory is deployed, it is also inited with an ENS name e.g. cowhooks.eth. For each proxy deployed on mainnet, it transfers the ownership of the reverse resolver node <address>.addr.reverse back to the factory contract and it is also set as the resolver. The reverse resolution will resolve to <proxy-owner>.cowhooks.eth.

At the time of initialization it also sets a subnode record for <user>.cowhooks.eth that resolves to the <proxy-address>. This allows user to get their proxy address by doing a simple ens lookup for <user-address>.cowhooks.eth. The reverse resolver will also allow anyone to lookup the proxy owner from the proxy address.

# forward resolution
$ cast resolve-name <user>.cowhooks.eth
<proxy-address>

# reverse resolution
$ cast lookup-address <proxy-address>
<user>.cowhooks.eth

Usage

Deployments

As cow-shed makes use of determinstic deployment, it has the same deployment address across all EVM-compatible chains. The contracts are deployed to the following addresses:

  • COWShedFactory: 0x00E989b87700514118Fa55326CD1cCE82faebEF6
  • COWShed: 0x2CFFA8cf11B90C9F437567b86352169dF4009F73 (implementation)

The contracts are deployed to the following networks:

  • mainnet
  • gnosis
  • arbitrum
  • sepolia

Tests

Fork testing is only used for the forward/reverse resolution testing of the ENS names for the proxies.

forge test -vvv --fork-url https://eth.llamarpc.com

Examples

Two examples are included for reference:

  1. ./examples/mintDaiAndSwap.ts - In this example, the user approves the proxy contract to take actions on its behalf on the maker protocol and uses prehooks to just-in-time(JIT) borrow DAI right before the DAI gets swapped to COW.
  2. ./examples/swapAndBridge.ts - In this example, the user uses the proxy address as the receiver for the swapped tokens and in the posthook it bridges the exact amount of swap output(weiroll is used for this) to gnosis chain with user's address as the recipient.
  3. ./examples/claimAndSwap.ts - In this example, the user claims WETH from a Llama Pay vesting contract using a prehook right before swapping it to COW.

The examples can be ran as follows:

yarn ts-node examples/<example.ts>