Bundler3

Bundler3 allows accounts to batch-execute a sequence of arbitrary calls atomically. It carries specific features to be able to perform actions that require authorizations, and handle callbacks.

Structure

Bundler3

Bundler3's entrypoint is multicall(Call[] calldata bundle). A bundle is a sequence of calls where each call is specified by:

• to, an address to call;
• data, some calldata to pass to the call;
• value, an amount of native currency to send with the call;
• skipRevert, a boolean indicating whether the multicall should revert if the call failed.
• callbackHash, hash of the argument to the expected reenter (0 if no reentrance).

Bundler3 also implements two specific features, their usage is described in the Adapters subsection:

• the initial caller is transiently stored as initiator during the multicall;
• the last non-returned called address can re-enter Bundler3 using reenter(Call[] calldata bundle), but the argument to the reenter call is specified in the bundle.

Adapters

Bundler3 can call either directly protocols, or wrappers of protocols (called "adapters"). Wrappers can be useful to perform “atomic checks" (e.g. slippage checks), manage slippage (e.g. in migrations) or perform actions that require authorizations.

In order to be safely authorized by users, adapters can restrict some functions calls depending on the value of the bundle's initiator, stored in Bundler3. For instance, an adapter that needs to hold some token approvals should call token.transferFrom only with from being the initiator.

Since these functions can typically move user funds, only Bundler3 should be allowed to call them. If an adapter gets called back (e.g. during a flashloan) and needs to perform more actions, it can use other adapters by calling Bundler3's reenter(Call[] calldata bundle) function.

Adapters List

All adapters inherit from CoreAdapter, which provides essential features such as accessing the current initiator address.

GeneralAdapter1

Contains the following actions:

• ERC20 transfers, wrap & unwrap.
• Native token (e.g. WETH) transfers, wrap & unwrap.
• ERC4626 mint, deposit, withdraw & redeem.
• Morpho interactions.
• TransferFrom using Permit2.

EthereumGeneralAdapter1

Contains the following actions:

• Actions of GeneralAdapter1.
• Morpho token wrapper withdrawal.
• stETH staking.
• wstETH wrap & unwrap.

ParaswapAdapter

Contains the following actions, all using the paraswap aggregator:

• Sell a given amount or the balance.
• Buy a given amount.
• Buy a what's needed to fully repay on a given Morpho Market.

Migration adapters

For Aave V2, Aave V3, Compound V2, Compound V3, and Morpho Aave V3 Optimizer.

Differences with Bundler v2

• Make use of transient storage.
• Bundler3 is now a call dispatcher that does not require any approval. Because call-dispatch and approvals are now separated, it is possible to add adapters over time without additional risk to users of existing adapters.
• All generic features are now in GeneralAdapter1, instead of being in separate files that are then all inherited by a single contract.
• All Ethereum related features are in the EthereumAdapter1 which inherits from GeneralAdapter1.
• The 1 after Adapter is not a version number: when new features are development we will deploy additional adapters, for instance GeneralAdapter2. Existing adapters will still be used.
• Many adjustments such as:
  • A value amount is only taken to be the current balance (when it makes sense) if equal to uint.max
  • Slippage checks are done with a price argument instead of a limit amount.
  • When shares represents a supply or borrow position, shares == uint.max sets shares to the position's total value.
  • There are receiver arguments in all functions that give tokens to the adapter so the adapter can pass along those tokens.
• The call fields skipRevert (to skip failed actions) and callbackHash (to commit to callback contents) are new.

Development

Run tests with forge test --chain <chainid> (chainid can be 1 or 8453, 1 by default).

Audits

All audits are stored in the audits folder.

License

Source files are licensed under GPL-2.0-or-later, see LICENSE.

Links

• Deployments
• SDK: TBA.