Rough reconstruciton of the source code for the contract at 0xa57Bd00134B2850B2a1c55860c9e9ea100fDd6CF on eth mainnet

ZeroXa57.sol

// SPDX-License-Identifier: MIT
pragma solidity 0.8.15;

// current thinking is that the original was compiled on 0.5.0 or 0.5.1

// after seeing significant code reuse from DSProxy, assumptions have been made

// the presence of cache() and setCache() imply usage of DSProxyCache
interface DSProxyCache {
    function read(bytes memory _code) external view returns (address);

    function write(bytes memory _code) external returns (address);
}


/// @title 0xa57
/// @dev a rough approximation of the contract at 0xa57Bd00134B2850B2a1c55860c9e9ea100fDd6CF on Ethereum mainnet
/// @notice still a work in progress, full of guesses
contract ZeroXa57 {
    mapping(address => uint) public wards;

    function rely(address usr) external {
        require(wards[msg.sender] == 1);
        wards[usr] = 1;
    }

    function deny(address usr) external {
        require(wards[msg.sender] == 1);
        wards[usr] = 0;
    }

    DSProxyCache public cache;

    constructor(address _cacheAddr) {
        setCache(_cacheAddr);
    }

    fallback() external payable {}

    // not sure this version returns anything, keeping ds-proxy's return values
    function execute(bytes memory _code, bytes memory _data)
        public
        payable
        returns (address target, bytes memory response)
    {
        target = cache.read(_code);
        if (target == address(0)) {
            // deploy contract & store its address in cache
            target = cache.write(_code);
        }

        response = execute(target, _data);
    }

    // this version of execute follows an old version of the function in
    // ds-proxy which does not return error msgs from failed delegatecalls
    // for example:
    // https://github.com/dapphub/ds-proxy/blob/9ccaf3d04d960a20ffbcb57041e0867d9e55b4f9/src/proxy.sol#L54-L79
    // not sure this version returns anything, keeping ds-proxy's return values
    function execute(address _target, bytes memory _data)
        public
        payable
        returns (bytes memory response)
    {
        require(wards[msg.sender] == 1);
        require(_target != 0x0);

        // call contract in current context
        assembly {
            let succeeded := delegatecall(sub(gas, 5000), _target, add(_data, 0x20), mload(_data), 0, 0)
            let size := returndatasize

            response := mload(0x40)
            mstore(0x40, add(response, and(add(add(size, 0x20), 0x1f), not(0x1f))))
            mstore(response, size)
            returndatacopy(add(response, 0x20), 0, size)

            switch iszero(succeeded)
            case 1 {
                // throw if delegatecall failed
                revert(0, 0)
            }
        }
    }

    // unknown function name, is otherwise identical to execute(bytes,bytes)
    // except that it seems to call 0x78e111f6 instead of execute(address,bytes)
    // not sure this version returns anything, keeping ds-proxy's return values
    function 0xa90e8731(bytes memory _code, bytes memory _data) 
        public
        payable 
        returns (address target, bytes memory response)
    {
        target = cache.read(_code);
        if (target == address(0)) {
            // deploy contract & store its address in cache
            target = cache.write(_code);
        }

        response = 0x78e111f6(target, _data);
    }

    // unknown function name, is otherwise identical to execute(address,bytes)
    // except that this one returns error msgs from a failed delegatecall
    // whereas the execute(address,bytes) used here does not
    // the code here is taken from later versions of ds-proxy, where execute
    // does return an error message
    // not sure this version returns anything, keeping ds-proxy's return values
    function 0x78e111f6(address _target, bytes memory _data) 
        public
        payable 
        returns (bytes memory response)
    {
        require(wards[msg.sender] == 1);
        require(_target != address(0), "ds-proxy-target-address-required");

        // call contract in current context
        assembly {
            let succeeded := delegatecall(
                sub(gas(), 5000),
                _target,
                add(_data, 0x20),
                mload(_data),
                0,
                0
            )
            let size := returndatasize()

            response := mload(0x40)
            mstore(
                0x40,
                add(response, and(add(add(size, 0x20), 0x1f), not(0x1f)))
            )
            mstore(response, size)
            returndatacopy(add(response, 0x20), 0, size)

            switch iszero(succeeded)
            case 1 {
                // throw if delegatecall failed
                revert(add(response, 0x20), size)
            }
        }
    }

    function setCache(address _cacheAddr) public payable returns (bool) {
        require(wards[msg.sender] == 1);
        require(_cacheAddr != address(0), "ds-proxy-cache-address-required");
        cache = DSProxyCache(_cacheAddr); // overwrite cache
        return true;
    }
}