Meta Transactions

Support for Meta Transactions

Our plugins are compatible with the ERC-2771 (Meta Transaction) standard, which allows users to send gasless transactions, also known as meta transactions. This is possible because we use _msgSender and _msgData context from OpenZeppelin's Context and ContextUpgradeable in our Plugin, PluginCloneable, and PluginUUPSUpgradeable classes.

To support meta transactions, your implementation contract must inherit and override the Context implementation with the _msgSender and _msgData functions provided in OpenGSN's BaseRelayRecipient, and use the DAO's trusted forwarder.

Below we show for the example of the TokenVoting plugin how you can make an existing plugin contract meta-transaction compatible.

import {ContextUpgradeable} from '@openzeppelin/contracts-upgradeable/utils/ContextUpgradeable.sol';
import {BaseRelayRecipient} from '@opengsn/contracts/src/BaseRelayRecipient.sol';

contract MyPlugin is PluginUUPSUpgradeable, BaseRelayRecipient {
  function initialize(IDAO _dao) external initializer {
    __PluginUUPSUpgradeable_init(_dao);
    _setTrustedForwarder(dao.getTrustedForwarder());
  }

  // ... the implementation

  function _msgSender()
    internal
    view
    virtual
    override(ContextUpgradeable, BaseRelayRecipient)
    returns (address)
  {
    return BaseRelayRecipient._msgSender();
  }

  function _msgData()
    internal
    view
    virtual
    override(ContextUpgradeable, BaseRelayRecipient)
    returns (bytes calldata)
  {
    return BaseRelayRecipient._msgData();
  }
}