feat: abstract common contracts and clean up (#78)

* chore: abstract common contracts

* chore: cleanup initialisers and constructors (#79)

* fix: vulnerability in abstraction

* fix: base relay recipient versioning

contracts/BaseDocumentStore.sol

@@ -0,0 +1,81 @@
+// SPDX-License-Identifier: Apache-2.0
+
+pragma solidity ^0.6.10;
+
+import "@openzeppelin/contracts/access/Ownable.sol";
+import "@openzeppelin/contracts-upgradeable/proxy/Initializable.sol";
+
+contract BaseDocumentStore is Initializable {
+  string public name;
+  string public version;
+
+  /// A mapping of the document hash to the block number that was issued
+  mapping(bytes32 => uint256) public documentIssued;
+  /// A mapping of the hash of the claim being revoked to the revocation block number
+  mapping(bytes32 => uint256) public documentRevoked;
+
+  event DocumentIssued(bytes32 indexed document);
+  event DocumentRevoked(bytes32 indexed document);
+
+  function initialize(string memory _name) public initializer {
+    version = "2.3.0";
+    name = _name;
+  }
+
+  function _issue(bytes32 document) internal onlyNotIssued(document) {
+    documentIssued[document] = block.number;
+    emit DocumentIssued(document);
+  }
+
+  function _bulkIssue(bytes32[] memory documents) internal {
+    for (uint256 i = 0; i < documents.length; i++) {
+      _issue(documents[i]);
+    }
+  }
+
+  function getIssuedBlock(bytes32 document) public view onlyIssued(document) returns (uint256) {
+    return documentIssued[document];
+  }
+
+  function isIssued(bytes32 document) public view returns (bool) {
+    return (documentIssued[document] != 0);
+  }
+
+  function isIssuedBefore(bytes32 document, uint256 blockNumber) public view returns (bool) {
+    return documentIssued[document] != 0 && documentIssued[document] <= blockNumber;
+  }
+
+  function _revoke(bytes32 document) internal onlyNotRevoked(document) returns (bool) {
+    documentRevoked[document] = block.number;
+    emit DocumentRevoked(document);
+  }
+
+  function _bulkRevoke(bytes32[] memory documents) internal {
+    for (uint256 i = 0; i < documents.length; i++) {
+      _revoke(documents[i]);
+    }
+  }
+
+  function isRevoked(bytes32 document) public view returns (bool) {
+    return documentRevoked[document] != 0;
+  }
+
+  function isRevokedBefore(bytes32 document, uint256 blockNumber) public view returns (bool) {
+    return documentRevoked[document] <= blockNumber && documentRevoked[document] != 0;
+  }
+
+  modifier onlyIssued(bytes32 document) {
+    require(isIssued(document), "Error: Only issued document hashes can be revoked");
+    _;
+  }
+
+  modifier onlyNotIssued(bytes32 document) {
+    require(!isIssued(document), "Error: Only hashes that have not been issued can be issued");
+    _;
+  }
+
+  modifier onlyNotRevoked(bytes32 claim) {
+    require(!isRevoked(claim), "Error: Hash has been revoked previously");
+    _;
+  }
+}

contracts/DocumentStore.sol

@@ -2,8 +2,11 @@
 
 pragma solidity ^0.6.10;
 
-import "./Ownable.sol";
+import "@openzeppelin/contracts/access/Ownable.sol";
 
+/*
+ * Legacy version for reference and backward compatibility, similar to OwnableDocumentStore
+ */
 contract DocumentStore is Ownable {
   string public name;
   string public version = "2.3.0";

contracts/GsnCapable.sol

@@ -2,81 +2,8 @@
 
 pragma solidity ^0.6.10;
 
-import "./Ownable.sol";
-
-// File: contracts/introspection/IERC165.sol
-
-/*
- * @dev Interface of the ERC165 standard, as defined in the
- * https://eips.ethereum.org/EIPS/eip-165[EIP].
- *
- * Implementers can declare support of contract interfaces, which can then be
- * queried by others ({ERC165Checker}).
- *
- * For an implementation, see {ERC165}.
- */
-interface IERC165 {
-  /**
-   * @dev Returns true if this contract implements the interface defined by
-   * `interfaceId`. See the corresponding
-   * https://eips.ethereum.org/EIPS/eip-165#how-interfaces-are-identified[EIP section]
-   * to learn more about how these ids are created.
-   *
-   * This function call must use less than 30 000 gas.
-   */
-  function supportsInterface(bytes4 interfaceId) external view returns (bool);
-}
-
-// File: contracts/introspection/ERC165.sol
-
-/**
- * @dev Implementation of the {IERC165} interface.
- *
- * Contracts may inherit from this and call {_registerInterface} to declare
- * their support of an interface.
- */
-contract ERC165 is IERC165 {
-  /*
-   * bytes4(keccak256('supportsInterface(bytes4)')) == 0x01ffc9a7
-   */
-  bytes4 private constant _INTERFACE_ID_ERC165 = 0x01ffc9a7;
-
-  /**
-   * @dev Mapping of interface ids to whether or not it's supported.
-   */
-  mapping(bytes4 => bool) private _supportedInterfaces;
-
-  constructor() internal {
-    // Derived contracts need only register support for their own interfaces,
-    // we register support for ERC165 itself here
-    _registerInterface(_INTERFACE_ID_ERC165);
-  }
-
-  /**
-   * @dev See {IERC165-supportsInterface}.
-   *
-   * Time complexity O(1), guaranteed to always use less than 30 000 gas.
-   */
-  function supportsInterface(bytes4 interfaceId) external override view returns (bool) {
-    return _supportedInterfaces[interfaceId];
-  }
-
-  /**
-   * @dev Registers the contract as an implementer of the interface defined by
-   * `interfaceId`. Support of the actual ERC165 interface is automatic and
-   * registering its interface id is not required.
-   *
-   * See {IERC165-supportsInterface}.
-   *
-   * Requirements:
-   *
-   * - `interfaceId` cannot be the ERC165 invalid interface (`0xffffffff`).
-   */
-  function _registerInterface(bytes4 interfaceId) internal {
-    require(interfaceId != 0xffffffff, "ERC165: invalid interface id");
-    _supportedInterfaces[interfaceId] = true;
-  }
-}
+import "@openzeppelin/contracts/access/Ownable.sol";
+import "@openzeppelin/contracts/introspection/ERC165.sol";
 
 contract GsnCapable is ERC165, Ownable {
   address public paymaster;
@@ -99,7 +26,7 @@ contract GsnCapable is ERC165, Ownable {
   }
 }
 
-contract calculateGsnCapableSelector {
+contract CalculateGsnCapableSelector {
   function calculateSelector() public pure returns (bytes4) {
     GsnCapable i;
     return i.setPaymaster.selector ^ i.getPaymaster.selector;

contracts/GsnCapableDocumentStore.sol

@@ -2,34 +2,33 @@
 
 pragma solidity ^0.6.10;
 
-import "./Ownable.sol";
-import "./DocumentStore.sol";
-import "./GsnCapable.sol";
 import "@opengsn/gsn/contracts/BaseRelayRecipient.sol";
 import "@opengsn/gsn/contracts/interfaces/IKnowForwarderAddress.sol";
 
-contract GsnCapableDocumentStore is DocumentStore, BaseRelayRecipient, IKnowForwarderAddress, GsnCapable {
-  constructor(string memory _name, address _forwarder) public DocumentStore(_name) {
+import "./OwnableDocumentStore.sol";
+import "./GsnCapable.sol";
+
+contract GsnCapableDocumentStore is OwnableDocumentStore, BaseRelayRecipient, IKnowForwarderAddress, GsnCapable {
+
+  string public override versionRecipient = "2.0.0";
+
+  constructor(string memory _name, address _forwarder) public OwnableDocumentStore(_name) {
     trustedForwarder = _forwarder;
   }
 
-  function _msgSender() internal override(Context, BaseRelayRecipient) view returns (address payable) {
+  function _msgSender() internal view override(Context, BaseRelayRecipient) returns (address payable) {
     return BaseRelayRecipient._msgSender();
   }
 
-  function _msgData() internal override(Context, BaseRelayRecipient) view returns (bytes memory) {
+  function _msgData() internal view override(Context, BaseRelayRecipient) returns (bytes memory) {
     return BaseRelayRecipient._msgData();
   }
 
-  function getTrustedForwarder() public override view returns (address) {
+  function getTrustedForwarder() public view override returns (address) {
     return trustedForwarder;
   }
 
   function setTrustedForwarder(address _forwarder) public onlyOwner {
     trustedForwarder = _forwarder;
   }
-
-  function versionRecipient() external virtual override view returns (string memory) {
-    return version;
-  }
 }