feat Consolidate logic (SC-5004) (#24)

* feat: consolidate all erc20 logic * fix: rm unused vm and invariant test files * feat: update README
maple-labs · Mar 10, 2022 · fd0cfde · fd0cfde
1 parent 552d0cc
commit fd0cfde
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diff --git a/README.md b/README.md
@@ -4,16 +4,14 @@
 
 **DISCLAIMER: This code has NOT been externally audited and is actively being developed. Please do not use in production without taking the appropriate steps to ensure maximum security.**
 
-<!-- TODO: Update this documentation to reflect new ERC20Permit implementation. -->
 Basic ERC-20 contract designed to be inherited and extended. Leveraging native overflow checks in solc 0.8 to simplify ERC-20 implementation. It should be noted that this ERC-20 implementation does not include some functionality that is commonly used in other tokens, such as:
 - `address(0)` checks on `_transfer`
-- `permit()`
 - `increaseAllowance`
 - `decreaseAllowance`
-- `push`
-- `pull`
 
-This was intentional, as this ERC-20 was intended to have the minimum functionality necessary, allowing for maximum extendability and customizability. 
+This was intentional, as this ERC-20 was intended to have the minimum functionality necessary, allowing for maximum extendability and customizability.
+
+This token implementation includes ERC-2612 [permit](https://eips.ethereum.org/EIPS/eip-2612) capability as well as `increaseAllowance` and `decreaseAllowance` functions.
 
 To clone, set up and run tests:
 ```

diff --git a/contracts/ERC20.sol b/contracts/ERC20.sol
@@ -9,6 +9,10 @@ import { IERC20 } from "./interfaces/IERC20.sol";
  */
 contract ERC20 is IERC20 {
 
+    /**************/
+    /*** ERC-20 ***/
+    /**************/
+
     string public override name;
     string public override symbol;
 
@@ -20,6 +24,15 @@ contract ERC20 is IERC20 {
 
     mapping(address => mapping(address => uint256)) public override allowance;
 
+    /****************/
+    /*** ERC-2612 ***/
+    /****************/
+
+    // PERMIT_TYPEHASH = keccak256("Permit(address owner,address spender,uint256 amount,uint256 nonce,uint256 deadline)");
+    bytes32 public constant override PERMIT_TYPEHASH = 0xfc77c2b9d30fe91687fd39abb7d16fcdfe1472d065740051ab8b13e4bf4a617f;
+
+    mapping (address => uint256) public override nonces;
+
     /**
      * @param name_     The name of the token.
      * @param symbol_   The symbol of the token.
@@ -50,6 +63,20 @@ contract ERC20 is IERC20 {
         return true;
     }
 
+    function permit(address owner, address spender, uint256 amount, uint256 deadline, uint8 v, bytes32 r, bytes32 s) external override {
+        require(deadline >= block.timestamp, "ERC20:P:EXPIRED");
+        bytes32 digest = keccak256(
+            abi.encodePacked(
+                "\x19\x01",
+                DOMAIN_SEPARATOR(),
+                keccak256(abi.encode(PERMIT_TYPEHASH, owner, spender, amount, nonces[owner]++, deadline))
+            )
+        );
+        address recoveredAddress = ecrecover(digest, v, r, s);
+        require(recoveredAddress == owner && owner != address(0), "ERC20:P:INVALID_SIGNATURE");
+        _approve(owner, spender, amount);
+    }
+
     function transfer(address recipient_, uint256 amount_) external override returns (bool success_) {
         _transfer(msg.sender, recipient_, amount_);
         return true;
@@ -61,6 +88,22 @@ contract ERC20 is IERC20 {
         return true;
     }
 
+    /**********************/
+    /*** View Functions ***/
+    /**********************/
+
+    function DOMAIN_SEPARATOR() public view override returns (bytes32 domainSeparator_) {
+        return keccak256(
+            abi.encode(
+                keccak256("EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)"),
+                keccak256(bytes(name)),
+                keccak256(bytes("1")),
+                block.chainid,
+                address(this)
+            )
+        );
+    }
+
     /**************************/
     /*** Internal Functions ***/
     /**************************/

diff --git a/contracts/ERC20Permit.sol b/contracts/ERC20Permit.sol
diff --git a/contracts/interfaces/IERC20.sol b/contracts/interfaces/IERC20.sol
@@ -1,9 +1,13 @@
 // SPDX-License-Identifier: AGPL-3.0-only
 pragma solidity ^0.8.7;
 
-/// @title Interface of the ERC20 standard as defined in the EIP.
+/// @title Interface of the ERC20 standard as defined in the EIP, including ERC-2612 permit functionality.
 interface IERC20 {
 
+    /**************/
+    /*** Events ***/
+    /**************/
+
     /**
      *  @dev   Emits an event indicating that tokens have moved from one account to another.
      *  @param owner_     Account that tokens have moved from.
@@ -20,38 +24,9 @@ interface IERC20 {
      */
     event Approval(address indexed owner_, address indexed spender_, uint256 amount_);
 
-    /**
-     *  @dev Returns the name of the token.
-     */
-    function name() external view returns (string memory name_);
-
-    /**
-     *  @dev Returns the symbol of the token.
-     */
-    function symbol() external view returns (string memory symbol_);
-
-    /**
-     *  @dev Returns the decimal precision used by the token.
-     */
-    function decimals() external view returns (uint8 decimals_);
-
-    /**
-     *  @dev Returns the total amount of tokens in existence.
-     */
-    function totalSupply() external view returns (uint256 totalSupply_);
-
-    /**
-     *  @dev   Returns the amount of tokens owned by a given account.
-     *  @param account_ Account that owns the tokens.
-     */
-    function balanceOf(address account_) external view returns (uint256 balance_);
-
-    /**
-     *  @dev   Function that returns the allowance that one account has given another over their tokens.
-     *  @param owner_   Account that tokens are approved from.
-     *  @param spender_ Account that tokens are approved for.
-     */
-    function allowance(address owner_, address spender_) external view returns (uint256 allowance_);
+    /**************************/
+    /*** External Functions ***/
+    /**************************/
 
     /**
      *  @dev    Function that allows one account to set the allowance of another account over their tokens.
@@ -80,6 +55,18 @@ interface IERC20 {
      */
     function increaseAllowance(address spender_, uint256 addedAmount_) external returns (bool success_);
 
+    /**
+     *  @dev   Approve by signature.
+     *  @param owner_    Owner address that signed the permit.
+     *  @param spender_  Spender of the permit.
+     *  @param amount_   Permit approval spend limit.
+     *  @param deadline_ Deadline after which the permit is invalid.
+     *  @param v_        ECDSA signature v component.
+     *  @param r_        ECDSA signature r component.
+     *  @param s_        ECDSA signature s component.
+     */
+    function permit(address owner_, address spender_, uint amount_, uint deadline_, uint8 v_, bytes32 r_, bytes32 s_) external;
+
     /**
      *  @dev    Moves an amount of tokens from `msg.sender` to a specified account.
      *          Emits a {Transfer} event.
@@ -100,4 +87,60 @@ interface IERC20 {
      */
     function transferFrom(address owner_, address recipient_, uint256 amount_) external returns (bool success_);
 
+    /**********************/
+    /*** View Functions ***/
+    /**********************/
+
+    /**
+     *  @dev   Function that returns the allowance that one account has given another over their tokens.
+     *  @param owner_   Account that tokens are approved from.
+     *  @param spender_ Account that tokens are approved for.
+     */
+    function allowance(address owner_, address spender_) external view returns (uint256 allowance_);
+
+    /**
+     *  @dev   Returns the amount of tokens owned by a given account.
+     *  @param account_ Account that owns the tokens.
+     */
+    function balanceOf(address account_) external view returns (uint256 balance_);
+
+    /**
+     *  @dev Returns the decimal precision used by the token.
+     */
+    function decimals() external view returns (uint8 decimals_);
+
+    /**
+     * @dev    Returns the signature domain separator.
+     * @return domainSeparator_ The domain for the contract.
+     */
+    function DOMAIN_SEPARATOR() external view returns (bytes32 domainSeparator_);
+
+    /**
+     *  @dev Returns the name of the token.
+     */
+    function name() external view returns (string memory name_);
+
+    /**
+      * @dev    Returns the nonce for the given owner.
+      * @param  owner The address of the owner account.
+      * @return nonce_ The current nonce.
+     */
+    function nonces(address owner) external view returns (uint256 nonce_);
+
+    /**
+     *  @dev    Returns the permit type hash.
+     *  @return hash_ The typehash for the commit.
+     */
+    function PERMIT_TYPEHASH() external view returns (bytes32 hash_);
+
+    /**
+     *  @dev Returns the symbol of the token.
+     */
+    function symbol() external view returns (string memory symbol_);
+
+    /**
+     *  @dev Returns the total amount of tokens in existence.
+     */
+    function totalSupply() external view returns (uint256 totalSupply_);
+
 }