Features: Gasless transactions.

.github/workflows/geth-test-deployment.yml

@@ -10,7 +10,7 @@ jobs:
 
     steps:
     - name: Checkout the code
-      uses: actions/checkout@v3
+      uses: actions/checkout@v4
 
     - name: Setup Nodejs
       uses: actions/setup-node@v3

.github/workflows/unit-tests.yml

@@ -10,7 +10,7 @@ jobs:
 
     steps:
     - name: Checkout the code
-      uses: actions/checkout@v3
+      uses: actions/checkout@v4
 
     - name: Setup Nodejs
       uses: actions/setup-node@v3
@@ -28,7 +28,7 @@ jobs:
         yarn coverage
 
     - name: Upload coverage report
-      uses: codecov/codecov-action@v2
+      uses: codecov/codecov-action@v4
       with:
         token: ${{ secrets.CODECOV_TOKEN }}
         fail_ci_if_error: true

contracts/common/AHasAutomatons.sol

@@ -3,7 +3,7 @@ pragma solidity 0.8.10;
 
 import "../lib/LibAddressSet.sol";
 import "../lib/LibPaginate.sol";
-import "../common/lib/LibHasAutomatons.sol";
+import "./lib/LibHasAutomatons.sol";
 
 /**
  * @title The Fast Smart Contract.

contracts/common/AHasContext.sol

@@ -0,0 +1,41 @@
+// SPDX-License-Identifier: MIT
+pragma solidity 0.8.10;
+
+/**
+ * @title The Context behaviour abstract contract.
+ * @notice The AHasContext abstract contract is in charge of adding the required
+ *         base implementation of ERC-2771 - see: https://eips.ethereum.org/EIPS/eip-2771
+ *         the key difference is that `isTrustedForwarder` becomes an internal method.
+ */
+abstract contract AHasContext {
+  /// @dev Must be implemented by the inheriting contract.
+  function _isTrustedForwarder(address forwarder) internal view virtual returns (bool);
+
+  // The following is copied from:
+  // https://github.com/opengsn/gsn/blob/v3.0.0-beta.10/packages/contracts/src/ERC2771Recipient.sol
+  // With a slight change to call `_isTrustedForwarder` instead of `isTrustedForwarder`.
+
+  /// @notice Default implemention.
+  function _msgSender() internal view virtual returns (address ret) {
+    if (msg.data.length >= 20 && _isTrustedForwarder(msg.sender)) {
+      // At this point we know that the sender is a trusted forwarder,
+      // so we trust that the last bytes of msg.data are the verified sender address.
+      // extract sender address from the end of msg.data
+      assembly {
+        ret := shr(96, calldataload(sub(calldatasize(), 20)))
+      }
+    } else {
+      ret = msg.sender;
+    }
+    return ret;
+  }
+
+  /// @notice Default implemention.
+  function _msgData() internal view virtual returns (bytes calldata ret) {
+    if (msg.data.length >= 20 && _isTrustedForwarder(msg.sender)) {
+      return msg.data[0:msg.data.length - 20];
+    } else {
+      return msg.data;
+    }
+  }
+}

contracts/common/AHasForwarder.sol

@@ -0,0 +1,80 @@
+// SPDX-License-Identifier: MIT
+pragma solidity 0.8.10;
+
+import "./lib/LibHasForwarder.sol";
+import "../interfaces/ICustomErrors.sol";
+import "../interfaces/IERC165.sol"; // Interface Support.
+
+import "@opengsn/contracts/src/forwarder/IForwarder.sol";
+
+/**
+ * @title The Forwarder behaviour abstract contract.
+ * @notice The AHasForwarder abstract contract is in charge of adding the Forwarder
+ *         functionality to any contract inheriting from it.
+ */
+abstract contract AHasForwarder {
+  /// Errors.
+
+  /**
+   * @notice Happens when a function is called by a non forwarder manager.
+   * @param who is the address that called the function.
+   */
+  error RequiresForwarderManager(address who);
+
+  /// Events.
+
+  /**
+   * @notice Emited when a forwarder is set on an implementing contract.
+   * @param forwarderAddress is the address of the trusted forwarder.
+   */
+  event ForwarderChanged(address forwarderAddress);
+
+  // SEE: https://github.com/opengsn/gsn/blob/v3.0.0-beta.10/packages/contracts/src/ERC2771Recipient.sol
+
+  /**
+   * @notice ERC2771Recipient implementation.
+   * @param _forwarderAddress the forwarder address.
+   * @return bool if the forwarder is trusted.
+   */
+  function isTrustedForwarder(address _forwarderAddress) public view returns (bool) {
+    return _forwarderAddress == LibHasForwarder.data().forwarderAddress;
+  }
+
+  /**
+   * @notice ERC2771Recipient implementation.
+   * @param _forwarderAddress the forwarder address.
+   */
+  function setTrustedForwarder(address _forwarderAddress) external onlyForwarderManager {
+    if (!IERC165(_forwarderAddress).supportsInterface(type(IForwarder).interfaceId))
+      revert ICustomErrors.InterfaceNotSupported("IForwarder");
+
+    LibHasForwarder.Data storage ds = LibHasForwarder.data();
+    ds.forwarderAddress = _forwarderAddress;
+
+    emit ForwarderChanged(_forwarderAddress);
+  }
+
+  /**
+   * WARNING: The Forwarder can have a full control over your Recipient. Only trust verified Forwarder.
+   * @notice Method is not a required method to allow Recipients to trust multiple Forwarders. Not recommended yet.
+   * @return forwarderAddress The address of the Forwarder contract that is being used.
+   */
+  function getTrustedForwarder() public view virtual returns (address forwarderAddress) {
+    return LibHasForwarder.data().forwarderAddress;
+  }
+
+  /**
+   * @notice Checks whether the given address is a forwarder manager or not.
+   * @dev Must be implemented by the inheriting contract.
+   * @param who is the address to test.
+   */
+  function isValidForwarderManager(address who) internal view virtual returns (bool);
+
+  /// Modifiers.
+
+  /// @notice Ensures that a method can only be called by the forwarder manager.
+  modifier onlyForwarderManager() virtual {
+    if (!isValidForwarderManager(msg.sender)) revert RequiresForwarderManager(msg.sender);
+    _;
+  }
+}

contracts/common/AHasGovernors.sol

@@ -3,8 +3,8 @@
 
 import "../lib/LibAddressSet.sol";
 import "../lib/LibPaginate.sol";
-import "../common/lib/LibHasGovernors.sol";
 import "../interfaces/ICustomErrors.sol";
+import "./lib/LibHasGovernors.sol";
 
 /**
  * @title The Fast Smart Contract.
@@ -33,6 +33,14 @@
    */
   event GovernorRemoved(address indexed governor);
 
+  /**
+   * @notice Default implementation - points to `_msgSender()`.
+   * @dev May be overriden by the inheriting contract.
+   */
+  function _msgSender() internal view virtual returns (address) {
+    return msg.sender;
+  }
+
   /**
    * @notice Checks whether the caller is a governor manager or not.
    * @dev Must be implemented by the inheriting contract.
@@ -94,7 +102,7 @@
    * @notice Adds a governor to the list of known governors.
    * @param who is the address to be added.
    */
-  function addGovernor(address who) external onlyGovernorManager(msg.sender) onlyValidGovernor(who) {
+  function addGovernor(address who) external onlyGovernorManager(_msgSender()) onlyValidGovernor(who) {
     // Add the governor.
     LibHasGovernors.data().governorSet.add(who, false);
     // Notify via callback.
@@ -109,7 +117,7 @@
    * @notice Requires that the caller is a governor of this Issuer.
    * @notice Emits a `AHasGovernors.GovernorRemoved` event.
    */
-  function removeGovernor(address governor) external onlyGovernorManager(msg.sender) {
+  function removeGovernor(address governor) external onlyGovernorManager(_msgSender()) {
     // Notify via callback.
     onGovernorRemoved(governor);
     // Remove governor.

contracts/common/AHasMembers.sol

@@ -3,11 +3,11 @@ pragma solidity 0.8.10;
 
 import "../lib/LibAddressSet.sol";
 import "../lib/LibPaginate.sol";
-import "../common/lib/LibHasMembers.sol";
 import "../interfaces/ICustomErrors.sol";
+import "./lib/LibHasMembers.sol";
 
 /**
- * @title The Fast Smart Contract.
+ * @title The Members behaviour abstract contract.
  * @notice The Fast Members abstract contract is in charge of keeping track of automaton accounts.
  */
 abstract contract AHasMembers {
@@ -33,6 +33,14 @@ abstract contract AHasMembers {
    */
   event MemberRemoved(address indexed member);
 
+  /**
+   * @notice Default implementation - points to `msg.sender`.
+   * @dev May be overriden by the inheriting contract.
+   */
+  function _msgSender() internal view virtual returns (address) {
+    return msg.sender;
+  }
+
   /**
    * @notice Checks whether the given address is a members manager or not.
    * @dev Must be implemented by the inheriting contract.
@@ -94,7 +102,7 @@ abstract contract AHasMembers {
    * @notice Adds a member to the list of known members.
    * @param who is the address to be added.
    */
-  function addMember(address who) external onlyMemberManager(msg.sender) onlyValidMember(who) {
+  function addMember(address who) external onlyMemberManager(_msgSender()) onlyValidMember(who) {
     // Add the member.
     LibHasMembers.data().memberSet.add(who, false);
     // Notify via callback.
@@ -109,7 +117,7 @@ abstract contract AHasMembers {
    * @notice Requires that the caller is a member of this Issuer.
    * @notice Emits a `AHasMembers.MemberRemoved` event.
    */
-  function removeMember(address member) external onlyMemberManager(msg.sender) {
+  function removeMember(address member) external onlyMemberManager(_msgSender()) {
     // Notify via callback.
     onMemberRemoved(member);
     // Remove member.

contracts/common/lib/LibHasForwarder.sol

@@ -0,0 +1,22 @@
+// SPDX-License-Identifier: MIT
+pragma solidity 0.8.10;
+
+library LibHasForwarder {
+  // The current version of the storage.
+  uint16 internal constant STORAGE_VERSION = 1;
+  // This is `keccak256('HasForwarder.storage.Main')`.
+  bytes32 internal constant STORAGE_SLOT = 0xa9930c2ffa1b605b0243ba36b3020146bcba5a29c05a711f5ca7c705a8e851ca;
+
+  struct Data {
+    /// @notice The latest intializer version that was called.
+    uint16 version;
+    /// @notice This is where we store the trusted forwarder address.
+    address forwarderAddress;
+  }
+
+  function data() internal pure returns (Data storage s) {
+    assembly {
+      s.slot := STORAGE_SLOT
+    }
+  }
+}

contracts/fast/FastAccessFacet.sol

@@ -3,6 +3,7 @@ pragma solidity 0.8.10;
 
 import "../lib/LibAddressSet.sol";
 import "../lib/LibPaginate.sol";
+import "../common/AHasContext.sol";
 import "../common/AHasMembers.sol";
 import "../common/AHasGovernors.sol";
 import "../marketplace/MarketplaceAccessFacet.sol";
@@ -19,7 +20,7 @@ import "./FastAutomatonsFacet.sol";
  * @notice The FAST Access facet is the source of truth when it comes to
  * permissioning and ACLs within a given FAST.
  */
-contract FastAccessFacet is AFastFacet, AHasGovernors, AHasMembers {
+contract FastAccessFacet is AFastFacet, AHasGovernors, AHasMembers, AHasContext {
   using LibAddressSet for LibAddressSet.Data;
   /// Structs.
 
@@ -35,6 +36,17 @@ contract FastAccessFacet is AFastFacet, AHasGovernors, AHasMembers {
     bool isMember;
   }
 
+  /// AHasContext implementation.
+
+  function _isTrustedForwarder(address forwarder) internal view override(AHasContext) returns (bool) {
+    return AHasForwarder(address(this)).isTrustedForwarder(forwarder);
+  }
+
+  // Override base classes to use the AHasContext implementation.
+  function _msgSender() internal view override(AHasMembers, AHasGovernors, AHasContext) returns (address) {
+    return AHasContext._msgSender();
+  }
+
   /// AHasGovernors implementation.
 
   function isGovernorsManager(address who) internal view override(AHasGovernors) returns (bool) {

contracts/fast/FastForwardableFacet.sol

@@ -0,0 +1,18 @@
+// SPDX-License-Identifier: MIT
+pragma solidity 0.8.10;
+
+import "../common/AHasForwarder.sol";
+import "./lib/AFastFacet.sol";
+
+/**
+ * @title The Fast forwardable contract.
+ * @notice The Fast Forwardable facet is in charge of "gasless transactions".
+ */
+contract FastForwardableFacet is AFastFacet, AHasForwarder {
+  /// AHasForwarder implementation.
+
+  // For now the forwarder manager is an issuer.
+  function isValidForwarderManager(address who) internal view override(AHasForwarder) returns (bool) {
+    return _isIssuerMember(who);
+  }
+}

contracts/fast/FastInitFacet.sol

@@ -4,6 +4,7 @@ pragma solidity 0.8.10;
 import "../common/lib/LibHasGovernors.sol";
 import "../common/lib/LibHasMembers.sol";
 import "../common/lib/LibHasAutomatons.sol";
+import "../common/lib/LibHasForwarder.sol";
 import "../common/AHasGovernors.sol";
 import "../common/AHasMembers.sol";
 import "../common/AHasAutomatons.sol";
@@ -113,5 +114,12 @@ contract FastInitFacet is AFastFacet {
 
     // Initialize automatons storage.
     LibHasAutomatons.data().version = LibHasAutomatons.STORAGE_VERSION;
+
+    // ------------------------------------- //
+
+    // Initialize forwarder storage.
+    LibHasForwarder.Data storage forwarderData = LibHasForwarder.data();
+    forwarderData.version = LibHasForwarder.STORAGE_VERSION;
+    forwarderData.forwarderAddress = address(0);
   }
 }

contracts/fast/FastTokenFacet.sol

@@ -136,7 +136,7 @@ contract FastTokenFacet is AFastFacet, IERC20 {
 
     // This operation can be seen as a regular transfer between holder and reserve. Emit.
     emit FastTransfer(msg.sender, holder, address(0), amount, DEAD_TOKENS_RETRIEVAL);
-    emit Transfer(holder, address(0), amount);
+    emit IERC20.Transfer(holder, address(0), amount);
 
     // If amount wasn't zero, total supply and reserve balance have changed - emit.
     if (amount > 0) FastFrontendFacet(address(this)).emitDetailsChanged();
@@ -437,7 +437,7 @@ contract FastTokenFacet is AFastFacet, IERC20 {
     }
 
     // Emit!
-    emit Approval(from, spender, amount);
+    emit IERC20.Approval(from, spender, amount);
   }
 
   /**

contracts/fast/lib/IFastEvents.sol

@@ -20,6 +20,7 @@ interface IFastEvents {
    * @param who is the account from which the minting operation originated.
    */
   event Minted(uint256 indexed amount, string ref, address indexed who);
+
   /**
    * @notice Emited whenever an burning happens in a FAST.
    * @param amount is the amount of tokens that have been burnt.
@@ -30,12 +31,9 @@ interface IFastEvents {
 
   /// Transfer and ERC20 stuff.
 
-  /// @notice See `ERC20.Transfer`.
-  event Transfer(address indexed from, address indexed to, uint256 value);
-  /// @notice See `ERC20.Approval`.
-  event Approval(address indexed owner, address indexed spender, uint256 value);
   /// @notice See `ERC20.Disapproval`.
   event Disapproval(address indexed owner, address indexed spender, uint256 value);
+
   /**
    * @notice As we augmented the ERC20 standard with a few concepts, we emit our custom events
    * in addition to the ERC20 ones.

contracts/interfaces/ICustomErrors.sol

@@ -7,6 +7,7 @@ interface ICustomErrors {
   error DuplicateEntry();
   error InconsistentParameter(string param);
   error InsufficientFunds(uint256 amount);
+  error InterfaceNotSupported(string);
   error InternalMethod();
   error InvalidCrowdfundBasisPointsFee(uint32 fee);
   error InvalidPhase();