Git Source

Inherits: ERC1967Proxy

Author: @ShaneDuncan602, @oscarsernarosero, @TJ-Everett

This is an example ERC721Proxy implementation that App Devs can use.

*This contract implements a proxy that is upgradeable by an admin. To avoid https://medium.com/nomic-labs-blog/malicious-backdoors-in-ethereum-proxies-62629adf3357[proxy selector clashing], which can potentially be used in an attack, this contract uses the https://blog.openzeppelin.com/the-transparent-proxy-pattern/[transparent proxy pattern]. This pattern implies two things that go hand in hand:

  1. If any account other than the admin calls the proxy, the call will be forwarded to the implementation, even if that call matches one of the admin functions exposed by the proxy itself.
  2. If the admin calls the proxy, it can access the admin functions, but its calls will never be forwarded to the implementation. If the admin tries to call a function on the implementation it will fail with an error that says “admin cannot fallback to proxy target”. These properties mean that the admin account can only be used for admin actions like upgrading the proxy or changing the admin, so it’s best if it’s a dedicated account that is not used for anything else. This will avoid headaches due to sudden errors when trying to call a function from the proxy implementation. Our recommendation is for the dedicated account to be an instance of the contract. If set up this way, you should think of the ProxyAdmin instance as the real administrative interface of your proxy.*

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Functions

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constructor

Initializes an upgradeable proxy managed by _admin, backed by the implementation at _logic, and optionally initialized with _data as explained in ERC1967Proxy-constructor.

constructor(address _logic, address admin_, bytes memory _data) payable ERC1967Proxy(_logic, _data);

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ifAdmin

Modifier used internally that will delegate the call to the implementation unless the sender is the admin.

modifier ifAdmin();

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admin

Returns the current admin. NOTE: Only the admin can call this function. See ProxyAdmin-getProxyAdmin. TIP: To get this value clients can read directly from the storage slot shown below (specified by EIP1967) using the https://eth.wiki/json-rpc/API#eth_getstorageat[`eth_getStorageAt`] RPC call. 0xb53127684a568b3173ae13b9f8a6016e243e63b6e8ee1178d6a717850b5d6103

function admin() external view ifAdmin returns (address admin_);

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implementation

Returns the current implementation. NOTE: Only the admin can call this function. See ProxyAdmin-getProxyImplementation. TIP: To get this value clients can read directly from the storage slot shown below (specified by EIP1967) using the https://eth.wiki/json-rpc/API#eth_getstorageat[`eth_getStorageAt`] RPC call. 0x360894a13ba1a3210667c828492db98dca3e2076cc3735a920a3ca505d382bbc

function implementation() external view ifAdmin returns (address implementation_);

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changeAdmin

Changes the admin of the proxy. Emits an event. NOTE: Only the admin can call this function. See {ProxyAdmin-changeProxyAdmin}.

function changeAdmin(address newAdmin) external virtual ifAdmin;

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upgradeTo

Upgrade the implementation of the proxy. NOTE: Only the admin can call this function. See ProxyAdmin-upgrade.

function upgradeTo(address newImplementation) external ifAdmin;

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upgradeToAndCall

Upgrade the implementation of the proxy, and then call a function from the new implementation as specified by data, which should be an encoded function call. This is useful to initialize new storage variables in the proxied contract. NOTE: Only the admin can call this function. See ProxyAdmin-upgradeAndCall.

function upgradeToAndCall(address newImplementation, bytes calldata data) external payable ifAdmin;

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_admin

Returns the current admin.

function _admin() internal view virtual returns (address);

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_beforeFallback

Makes sure the admin cannot access the fallback function. See Proxy-_beforeFallback.

function _beforeFallback() internal virtual override;
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