add transfer validator to v1

config/.solhintignore

@@ -4,5 +4,7 @@ src/clones
 src/test/
 src/shim/
 
+src/interfaces/ITransferValidator.sol
+
 test/
 lib/

src-upgradeable/src/ERC721ContractMetadataStorage.sol

@@ -24,6 +24,9 @@ library ERC721ContractMetadataStorage {
         /// @notice Track the royalty info: address to receive royalties, and
         ///         royalty basis points.
         ISeaDropTokenContractMetadataUpgradeable.RoyaltyInfo _royaltyInfo;
+        /// @notice Track the transfer validator.
+        ///         The null address means no transfer validator is set.
+        address _transferValidator;
     }
 
     bytes32 internal constant STORAGE_SLOT =

src-upgradeable/src/ERC721ContractMetadataUpgradeable.sol

@@ -6,8 +6,14 @@ import {
 } from "./interfaces/ISeaDropTokenContractMetadataUpgradeable.sol";
 
 import {
-    ERC721AUpgradeable
-} from "../lib/ERC721A-Upgradeable/contracts/ERC721AUpgradeable.sol";
+    ERC721AConduitPreapprovedUpgradeable
+} from "./lib/ERC721AConduitPreapprovedUpgradeable.sol";
+
+import {
+    ERC721TransferValidatorUpgradeable
+} from "./lib/ERC721TransferValidatorUpgradeable.sol";
+
+import { ERC721AUpgradeable } from "../lib/ERC721A-Upgradeable/contracts/ERC721AUpgradeable.sol";
 
 import {
     TwoStepOwnableUpgradeable
@@ -34,7 +40,7 @@ import {
  *         with additional metadata and ownership capabilities.
  */
 contract ERC721ContractMetadataUpgradeable is
-    ERC721AUpgradeable,
+    ERC721AConduitPreapprovedUpgradeable,
     TwoStepOwnableUpgradeable,
     ISeaDropTokenContractMetadataUpgradeable
 {
@@ -61,17 +67,11 @@ contract ERC721ContractMetadataUpgradeable is
         string memory name,
         string memory symbol
     ) internal onlyInitializing {
-        __ERC721A_init_unchained(name, symbol);
+        __ERC721AConduitPreapprovedUpgradeable_init_unchained(name, symbol);
         __ConstructorInitializable_init_unchained();
         __TwoStepOwnable_init_unchained();
-        __ERC721ContractMetadata_init_unchained(name, symbol);
     }
 
-    function __ERC721ContractMetadata_init_unchained(
-        string memory,
-        string memory
-    ) internal onlyInitializing {}
-
     /**
      * @notice Sets the base URI for the token metadata and emits an event.
      *
@@ -270,7 +270,8 @@ contract ERC721ContractMetadataUpgradeable is
      * @return royaltyAmount The royalty payment amount for _salePrice.
      */
     function royaltyInfo(
-        uint256, /* _tokenId */
+        uint256,
+        /* _tokenId */
         uint256 _salePrice
     ) external view returns (address receiver, uint256 royaltyAmount) {
         // Put the royalty info on the stack for more efficient access.
@@ -286,6 +287,37 @@ contract ERC721ContractMetadataUpgradeable is
         receiver = info.royaltyAddress;
     }
 
+    /**
+     * @notice Set the transfer validator. Only callable by the token owner.
+     */
+    function setTransferValidator(address newValidator) external onlyOwner {
+        // Set the new transfer validator.
+        _setTransferValidator(newValidator);
+    }
+
+    /**
+     * @dev Hook that is called before any token transfer.
+     *      This includes minting and burning.
+     */
+    function _beforeTokenTransfers(
+        address from,
+        address to,
+        uint256 startTokenId,
+        uint256 /* quantity */
+    ) internal virtual override {
+        if (from != address(0) && to != address(0)) {
+            // Call the transfer validator if one is set.
+            if (_transferValidator != address(0)) {
+                ITransferValidator(_transferValidator).validateTransfer(
+                    msg.sender,
+                    from,
+                    to,
+                    startTokenId
+                );
+            }
+        }
+    }
+
     /**
      * @notice Returns whether the interface is supported.
      *

src-upgradeable/src/interfaces/ITransferValidator.sol

@@ -0,0 +1,21 @@
+// SPDX-License-Identifier: MIT
+pragma solidity 0.8.17;
+
+interface ITransferValidator {
+    /// @notice Ensure that a transfer has been authorized for a specific tokenId
+    function validateTransfer(
+        address caller,
+        address from,
+        address to,
+        uint256 tokenId
+    ) external view;
+
+    /// @notice Ensure that a transfer has been authorized for a specific amount of a specific tokenId, and reduce the transferable amount remaining
+    function validateTransfer(
+        address caller,
+        address from,
+        address to,
+        uint256 tokenId,
+        uint256 amount
+    ) external;
+}

src-upgradeable/src/lib/ERC721AConduitPreapprovedUpgradeable.sol

@@ -0,0 +1,33 @@
+// SPDX-License-Identifier: MIT
+pragma solidity 0.8.17;
+
+import { ERC721AUpgradeable } from "../../lib/ERC721A-Upgradeable/contracts/ERC721AUpgradeable.sol";
+
+/**
+ * @title  ERC721AConduitPreapproved
+ * @notice ERC721A with the OpenSea conduit preapproved.
+ */
+abstract contract ERC721AConduitPreapprovedUpgradeable is ERC721AUpgradeable {
+    /// @dev The canonical OpenSea conduit.
+    address internal constant _CONDUIT = 0x1E0049783F008A0085193E00003D00cd54003c71;
+
+    /**
+     * @notice Deploy the token contract with its name and symbol.
+     */
+    function __ERC721AConduitPreapprovedUpgradeable_init_unchained(
+        string memory name, string memory symbol
+    ) internal onlyInitializing {
+        __ERC721A_init_unchained(name, symbol);
+    }
+
+    /**
+     * @dev Returns if the `operator` is allowed to manage all of the
+     *      assets of `owner`. Always returns true for the conduit.
+     */
+    function isApprovedForAll(address owner, address operator) public view virtual override returns (bool) {
+        if (operator == _CONDUIT) {
+            return true;
+        }
+        return ERC721A.isApprovedForAll(owner, operator);
+    }
+}

src-upgradeable/src/lib/ERC721TransferValidatorUpgradeable.sol

@@ -0,0 +1,35 @@
+// SPDX-License-Identifier: MIT
+pragma solidity 0.8.17;
+
+import {ERC721ContractMetadataStorage} from "../ERC721ContractMetadataStorage.sol";
+
+/**
+ * @title  ERC721TransferValidatorUpgradeable
+ * @notice Functionality to use a transfer validator.
+ */
+contract ERC721TransferValidatorUpgradeable {
+    using ERC721ContractMetadataStorage for ERC721ContractMetadataStorage.Layout;
+
+    /// @notice Emit an event when the transfer validator is updated.
+    event TransferValidatorUpdated(address oldValidator, address newValidator);
+
+    /// @notice Revert with an error if the transfer validator is being set to the same address.
+    error SameTransferValidator();
+
+    /// @notice Returns the currently active transfer validator.
+    ///         The null address means no transfer validator is set.
+    function getTransferValidator() external view returns (address) {
+        return ERC721ContractMetadataStorage.layout()._transferValidator;
+    }
+
+    /// @notice Set the transfer validator.
+    ///         The external method that uses this must include access control.
+    function _setTransferValidator(address newValidator) internal {
+        address oldValidator = ERC721ContractMetadataStorage.layout()._transferValidator;
+        if (oldValidator == newValidator) {
+            revert SameTransferValidator();
+        }
+        ERC721ContractMetadataStorage.layout()._transferValidator = newValidator;
+        emit TransferValidatorUpdated(oldValidator, newValidator);
+    }
+}

src/ERC721ContractMetadata.sol

@@ -9,6 +9,10 @@ import { ERC721A } from "ERC721A/ERC721A.sol";
 
 import { ERC721AConduitPreapproved } from "./lib/ERC721AConduitPreapproved.sol";
 
+import { ERC721TransferValidator } from "./lib/ERC721TransferValidator.sol";
+
+import { ITransferValidator } from "./interfaces/ITransferValidator.sol";
+
 import { TwoStepOwnable } from "utility-contracts/TwoStepOwnable.sol";
 
 import { IERC2981 } from "openzeppelin-contracts/interfaces/IERC2981.sol";
@@ -27,6 +31,7 @@ import {
  */
 contract ERC721ContractMetadata is
     ERC721AConduitPreapproved,
+    ERC721TransferValidator,
     TwoStepOwnable,
     ISeaDropTokenContractMetadata
 {
@@ -261,7 +266,8 @@ contract ERC721ContractMetadata is
      * @return royaltyAmount The royalty payment amount for _salePrice.
      */
     function royaltyInfo(
-        uint256, /* _tokenId */
+        uint256,
+        /* _tokenId */
         uint256 _salePrice
     ) external view returns (address receiver, uint256 royaltyAmount) {
         // Put the royalty info on the stack for more efficient access.
@@ -275,6 +281,37 @@ contract ERC721ContractMetadata is
         receiver = info.royaltyAddress;
     }
 
+    /**
+     * @notice Set the transfer validator. Only callable by the token owner.
+     */
+    function setTransferValidator(address newValidator) external onlyOwner {
+        // Set the new transfer validator.
+        _setTransferValidator(newValidator);
+    }
+
+    /**
+     * @dev Hook that is called before any token transfer.
+     *      This includes minting and burning.
+     */
+    function _beforeTokenTransfers(
+        address from,
+        address to,
+        uint256 startTokenId,
+        uint256 /* quantity */
+    ) internal virtual override {
+        if (from != address(0) && to != address(0)) {
+            // Call the transfer validator if one is set.
+            if (_transferValidator != address(0)) {
+                ITransferValidator(_transferValidator).validateTransfer(
+                    msg.sender,
+                    from,
+                    to,
+                    startTokenId
+                );
+            }
+        }
+    }
+
     /**
      * @notice Returns whether the interface is supported.
      *

src/clones/ERC721AConduitPreapprovedCloneable.sol

@@ -0,0 +1,31 @@
+// SPDX-License-Identifier: MIT
+pragma solidity 0.8.17;
+
+import { ERC721ACloneable } from "./ERC721ACloneable.sol";
+
+/**
+ * @title  ERC721AConduitPreapprovedCloneable
+ * @notice ERC721A with the OpenSea conduit preapproved.
+ */
+abstract contract ERC721AConduitPreapprovedCloneable is ERC721ACloneable {
+    /// @dev The canonical OpenSea conduit.
+    address internal constant _CONDUIT =
+        0x1E0049783F008A0085193E00003D00cd54003c71;
+
+    /**
+     * @dev Returns if the `operator` is allowed to manage all of the
+     *      assets of `owner`. Always returns true for the conduit.
+     */
+    function isApprovedForAll(address owner, address operator)
+        public
+        view
+        virtual
+        override
+        returns (bool)
+    {
+        if (operator == _CONDUIT) {
+            return true;
+        }
+        return ERC721ACloneable.isApprovedForAll(owner, operator);
+    }
+}

src/clones/ERC721ContractMetadataCloneable.sol

@@ -5,8 +5,16 @@ import {
     ISeaDropTokenContractMetadata
 } from "../interfaces/ISeaDropTokenContractMetadata.sol";
 
+import {
+    ERC721AConduitPreapprovedCloneable
+} from "./ERC721AConduitPreapprovedCloneable.sol";
+
 import { ERC721ACloneable } from "./ERC721ACloneable.sol";
 
+import { ERC721TransferValidator } from "../lib/ERC721TransferValidator.sol";
+
+import { ITransferValidator } from "../interfaces/ITransferValidator.sol";
+
 import { TwoStepOwnable } from "utility-contracts/TwoStepOwnable.sol";
 
 import { IERC2981 } from "openzeppelin-contracts/interfaces/IERC2981.sol";
@@ -24,7 +32,8 @@ import {
  *         with additional metadata and ownership capabilities.
  */
 contract ERC721ContractMetadataCloneable is
-    ERC721ACloneable,
+    ERC721AConduitPreapprovedCloneable,
+    ERC721TransferValidator,
     TwoStepOwnable,
     ISeaDropTokenContractMetadata
 {
@@ -267,6 +276,37 @@ contract ERC721ContractMetadataCloneable is
         receiver = info.royaltyAddress;
     }
 
+    /**
+     * @notice Set the transfer validator. Only callable by the token owner.
+     */
+    function setTransferValidator(address newValidator) external onlyOwner {
+        // Set the new transfer validator.
+        _setTransferValidator(newValidator);
+    }
+
+    /**
+     * @dev Hook that is called before any token transfer.
+     *      This includes minting and burning.
+     */
+    function _beforeTokenTransfers(
+        address from,
+        address to,
+        uint256 startTokenId,
+        uint256 /* quantity */
+    ) internal virtual override {
+        if (from != address(0) && to != address(0)) {
+            // Call the transfer validator if one is set.
+            if (_transferValidator != address(0)) {
+                ITransferValidator(_transferValidator).validateTransfer(
+                    msg.sender,
+                    from,
+                    to,
+                    startTokenId
+                );
+            }
+        }
+    }
+
     /**
      * @notice Returns whether the interface is supported.
      *

src/interfaces/ITransferValidator.sol

@@ -0,0 +1,22 @@
+// SPDX-License-Identifier: MIT
+pragma solidity 0.8.17;
+
+interface ITransferValidator {
+    /// @notice Ensure that a transfer has been authorized for a specific tokenId.
+    function validateTransfer(
+        address caller,
+        address from,
+        address to,
+        uint256 tokenId
+    ) external view;
+
+    /// @notice Ensure that a transfer has been authorized for a specific amount of
+    //          a specific tokenId, and reduce the transferable amount remaining.
+    function validateTransfer(
+        address caller,
+        address from,
+        address to,
+        uint256 tokenId,
+        uint256 amount
+    ) external;
+}