feat: add SafeERC20 dependency

contracts/dependencies/openzeppelin/contracts/Address.sol

@@ -1,5 +1,7 @@
-// SPDX-License-Identifier: AGPL-3.0
-pragma solidity 0.8.10;
+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts v4.4.1 (utils/Address.sol)
+
+pragma solidity ^0.8.0;
 
 /**
  * @dev Collection of functions related to the address type
@@ -23,16 +25,15 @@ library Address {
    * ====
    */
   function isContract(address account) internal view returns (bool) {
-    // According to EIP-1052, 0x0 is the value returned for not-yet created accounts
-    // and 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470 is returned
-    // for accounts without code, i.e. `keccak256('')`
-    bytes32 codehash;
-    bytes32 accountHash = 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470;
-    // solhint-disable-next-line no-inline-assembly
+    // This method relies on extcodesize, which returns 0 for contracts in
+    // construction, since the code is only stored at the end of the
+    // constructor execution.
+
+    uint256 size;
     assembly {
-      codehash := extcodehash(account)
+      size := extcodesize(account)
     }
-    return (codehash != accountHash && codehash != 0x0);
+    return size > 0;
   }
 
   /**
@@ -54,8 +55,166 @@ library Address {
   function sendValue(address payable recipient, uint256 amount) internal {
     require(address(this).balance >= amount, 'Address: insufficient balance');
 
-    // solhint-disable-next-line avoid-low-level-calls, avoid-call-value
     (bool success, ) = recipient.call{value: amount}('');
     require(success, 'Address: unable to send value, recipient may have reverted');
   }
+
+  /**
+   * @dev Performs a Solidity function call using a low level `call`. A
+   * plain `call` is an unsafe replacement for a function call: use this
+   * function instead.
+   *
+   * If `target` reverts with a revert reason, it is bubbled up by this
+   * function (like regular Solidity function calls).
+   *
+   * Returns the raw returned data. To convert to the expected return value,
+   * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
+   *
+   * Requirements:
+   *
+   * - `target` must be a contract.
+   * - calling `target` with `data` must not revert.
+   *
+   * _Available since v3.1._
+   */
+  function functionCall(address target, bytes memory data) internal returns (bytes memory) {
+    return functionCall(target, data, 'Address: low-level call failed');
+  }
+
+  /**
+   * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
+   * `errorMessage` as a fallback revert reason when `target` reverts.
+   *
+   * _Available since v3.1._
+   */
+  function functionCall(
+    address target,
+    bytes memory data,
+    string memory errorMessage
+  ) internal returns (bytes memory) {
+    return functionCallWithValue(target, data, 0, errorMessage);
+  }
+
+  /**
+   * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
+   * but also transferring `value` wei to `target`.
+   *
+   * Requirements:
+   *
+   * - the calling contract must have an ETH balance of at least `value`.
+   * - the called Solidity function must be `payable`.
+   *
+   * _Available since v3.1._
+   */
+  function functionCallWithValue(
+    address target,
+    bytes memory data,
+    uint256 value
+  ) internal returns (bytes memory) {
+    return functionCallWithValue(target, data, value, 'Address: low-level call with value failed');
+  }
+
+  /**
+   * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
+   * with `errorMessage` as a fallback revert reason when `target` reverts.
+   *
+   * _Available since v3.1._
+   */
+  function functionCallWithValue(
+    address target,
+    bytes memory data,
+    uint256 value,
+    string memory errorMessage
+  ) internal returns (bytes memory) {
+    require(address(this).balance >= value, 'Address: insufficient balance for call');
+    require(isContract(target), 'Address: call to non-contract');
+
+    (bool success, bytes memory returndata) = target.call{value: value}(data);
+    return verifyCallResult(success, returndata, errorMessage);
+  }
+
+  /**
+   * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
+   * but performing a static call.
+   *
+   * _Available since v3.3._
+   */
+  function functionStaticCall(
+    address target,
+    bytes memory data
+  ) internal view returns (bytes memory) {
+    return functionStaticCall(target, data, 'Address: low-level static call failed');
+  }
+
+  /**
+   * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
+   * but performing a static call.
+   *
+   * _Available since v3.3._
+   */
+  function functionStaticCall(
+    address target,
+    bytes memory data,
+    string memory errorMessage
+  ) internal view returns (bytes memory) {
+    require(isContract(target), 'Address: static call to non-contract');
+
+    (bool success, bytes memory returndata) = target.staticcall(data);
+    return verifyCallResult(success, returndata, errorMessage);
+  }
+
+  /**
+   * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
+   * but performing a delegate call.
+   *
+   * _Available since v3.4._
+   */
+  function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
+    return functionDelegateCall(target, data, 'Address: low-level delegate call failed');
+  }
+
+  /**
+   * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
+   * but performing a delegate call.
+   *
+   * _Available since v3.4._
+   */
+  function functionDelegateCall(
+    address target,
+    bytes memory data,
+    string memory errorMessage
+  ) internal returns (bytes memory) {
+    require(isContract(target), 'Address: delegate call to non-contract');
+
+    (bool success, bytes memory returndata) = target.delegatecall(data);
+    return verifyCallResult(success, returndata, errorMessage);
+  }
+
+  /**
+   * @dev Tool to verifies that a low level call was successful, and revert if it wasn't, either by bubbling the
+   * revert reason using the provided one.
+   *
+   * _Available since v4.3._
+   */
+  function verifyCallResult(
+    bool success,
+    bytes memory returndata,
+    string memory errorMessage
+  ) internal pure returns (bytes memory) {
+    if (success) {
+      return returndata;
+    } else {
+      // Look for revert reason and bubble it up if present
+      if (returndata.length > 0) {
+        // The easiest way to bubble the revert reason is using memory via assembly
+
+        assembly {
+          let returndata_size := mload(returndata)
+          revert(add(32, returndata), returndata_size)
+        }
+      } else {
+        revert(errorMessage);
+      }
+    }
+  }
 }

contracts/dependencies/openzeppelin/contracts/SafeERC20.sol

@@ -0,0 +1,87 @@
+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts v4.4.1 (token/ERC20/utils/SafeERC20.sol)
+
+pragma solidity ^0.8.0;
+
+import './IERC20.sol';
+import './Address.sol';
+
+/**
+ * @title SafeERC20
+ * @dev Wrappers around ERC20 operations that throw on failure (when the token
+ * contract returns false). Tokens that return no value (and instead revert or
+ * throw on failure) are also supported, non-reverting calls are assumed to be
+ * successful.
+ * To use this library you can add a `using SafeERC20 for IERC20;` statement to your contract,
+ * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
+ */
+library SafeERC20 {
+  using Address for address;
+
+  function safeTransfer(IERC20 token, address to, uint256 value) internal {
+    _callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
+  }
+
+  function safeTransferFrom(IERC20 token, address from, address to, uint256 value) internal {
+    _callOptionalReturn(
+      token,
+      abi.encodeWithSelector(token.transferFrom.selector, from, to, value)
+    );
+  }
+
+  /**
+   * @dev Deprecated. This function has issues similar to the ones found in
+   * {IERC20-approve}, and its usage is discouraged.
+   *
+   * Whenever possible, use {safeIncreaseAllowance} and
+   * {safeDecreaseAllowance} instead.
+   */
+  function safeApprove(IERC20 token, address spender, uint256 value) internal {
+    // safeApprove should only be called when setting an initial allowance,
+    // or when resetting it to zero. To increase and decrease it, use
+    // 'safeIncreaseAllowance' and 'safeDecreaseAllowance'
+    require(
+      (value == 0) || (token.allowance(address(this), spender) == 0),
+      'SafeERC20: approve from non-zero to non-zero allowance'
+    );
+    _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));
+  }
+
+  function safeIncreaseAllowance(IERC20 token, address spender, uint256 value) internal {
+    uint256 newAllowance = token.allowance(address(this), spender) + value;
+    _callOptionalReturn(
+      token,
+      abi.encodeWithSelector(token.approve.selector, spender, newAllowance)
+    );
+  }
+
+  function safeDecreaseAllowance(IERC20 token, address spender, uint256 value) internal {
+    unchecked {
+      uint256 oldAllowance = token.allowance(address(this), spender);
+      require(oldAllowance >= value, 'SafeERC20: decreased allowance below zero');
+      uint256 newAllowance = oldAllowance - value;
+      _callOptionalReturn(
+        token,
+        abi.encodeWithSelector(token.approve.selector, spender, newAllowance)
+      );
+    }
+  }
+
+  /**
+   * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
+   * on the return value: the return value is optional (but if data is returned, it must not be false).
+   * @param token The token targeted by the call.
+   * @param data The call data (encoded using abi.encode or one of its variants).
+   */
+  function _callOptionalReturn(IERC20 token, bytes memory data) private {
+    // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
+    // we're implementing it ourselves. We use {Address.functionCall} to perform this call, which verifies that
+    // the target address contains contract code and also asserts for success in the low-level call.
+
+    bytes memory returndata = address(token).functionCall(data, 'SafeERC20: low-level call failed');
+    if (returndata.length > 0) {
+      // Return data is optional
+      require(abi.decode(returndata, (bool)), 'SafeERC20: ERC20 operation did not succeed');
+    }
+  }
+}