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Automatically merged updates to draft EIP(s) 1167

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EIPS/eip-1167.md
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@ -16,7 +16,7 @@ created: 2018-06-22
To simply and cheaply clone contract functionality in an immutable way, we propose to standardize on a minimal bytecode implementation which delegates all calls to a known, fixed address.
## Abstract
<!--A short (~200 word) description of the technical issue being addressed.-->
By standardizing on a known minimal bytecode redirect implementation, this standard will allow users and third party tools (e.g. Etherscan) to (a) simply discover that a contract will always redirect in a known manner and (b) depend on the behavior of the code at the destination contract as the behavior of the redirecting contract. Specifically, tooling can interrogate the bytecode at a redirecting address to determine the location of the code that will run - and can depend on representations about that code (verified source, third-party audits, etc). We have an implementation we believe to be minimal and covering both standard calls and
By standardizing on a known minimal bytecode redirect implementation, this standard will allow users and third party tools (e.g. Etherscan) to (a) simply discover that a contract will always redirect in a known manner and (b) depend on the behavior of the code at the destination contract as the behavior of the redirecting contract. Specifically, tooling can interrogate the bytecode at a redirecting address to determine the location of the code that will run - and can depend on representations about that code (verified source, third-party audits, etc). This implementation forwards all calls and 100% of the gas to the implementation contract and then relays the return value back to the caller. In the case where the implementation reverts, the revert is passed back along with the payload data (for revert with message).
## Motivation
@ -25,7 +25,9 @@ This standard is desireable to allow for use-cases wherein it is desireable to c
## Specification
<!--The technical specification should describe the syntax and semantics of any new feature. The specification should be detailed enough to allow competing, interoperable implementations for any of the current Ethereum platforms (go-ethereum, parity, cpp-ethereum, ethereumj, ethereumjs, and [others](https://github.com/ethereum/wiki/wiki/Clients)).-->
The exact bytecode of the standard clone contract is this: `6000368180378080368173bebebebebebebebebebebebebebebebebebebebe5af43d82803e15602c573d90f35b3d90fd` wherein the bytes at idices 10 - 29 (inclusive) are replaced with the 20 byte address of the master functionality contract. The reference implementation of this is found at the [optionality/clone-factory](https://github.com/optionality/clone-factory) github repo. There are variations as well for using vanity contract addresses with leading zeros to further shrink the necessary clone bytecode (thus making it cheaper to deploy). Detection of clone and redirection is implemented in the clone-factory repo with a contract deployed on both Kovan and Mainnet that detects the presence of a clone and returns the destination address if the interrogated contract is a clone (handles shortened addresses as well).
The exact bytecode of the standard clone contract is this: `6000368180378080368173bebebebebebebebebebebebebebebebebebebebe5af43d82803e15602c573d90f35b3d90fd` wherein the bytes at idices 10 - 29 (inclusive) are replaced with the 20 byte address of the master functionality contract. The reference implementation of this is found at the [optionality/clone-factory](https://github.com/optionality/clone-factory) github repo.
Detection of clone and redirection is implemented in the clone-factory repo with a contract deployed on both Kovan and Mainnet that detects the presence of a clone and returns the destination address if the interrogated contract is a clone (handles shortened addresses as well).
## Rationale
<!--The rationale fleshes out the specification by describing what motivated the design and why particular design decisions were made. It should describe alternate designs that were considered and related work, e.g. how the feature is supported in other languages. The rationale may also provide evidence of consensus within the community, and should discuss important objections or concerns raised during discussion.-->
@ -47,7 +49,179 @@ We have included some simple test cases in the clone-factory project that demons
## Implementation
<!--The implementations must be completed before any EIP is given status "Final", but it need not be completed before the EIP is accepted. While there is merit to the approach of reaching consensus on the specification and rationale before writing code, the principle of "rough consensus and running code" is still useful when it comes to resolving many discussions of API details.-->
Please see [optionality/clone-factory](https://github.com/optionality/clone-factory)
The exact bytecode for deploying the clone instances is `600034603b57603080600f833981f36000368180378080368173bebebebebebebebebebebebebebebebebebebebe5af43d82803e15602c573d90f35b3d90fd` with the 20 'be' bytes at offset 26 replaced with the address of the implementation contract. This deployment bytecode results in a deployed contract of `6000368180378080368173bebebebebebebebebebebebebebebebebebebebe5af43d82803e15602c573d90f35b3d90fd`.
The disassembly of the full deployment code (from r2, then edited to account for deployment offset changes)
```
0x00000000 6000 push1 0x0
0x00000002 34 callvalue
0x00000003 603b push1 0x3b
,=< 0x00000005 57 jumpi
| 0x00000006 6030 push1 0x30
| 0x00000008 80 dup1
| 0x00000009 600f push1 0xf
| 0x0000000b 83 dup4
| 0x0000000c 39 codecopy
| 0x0000000d 81 dup2
| 0x0000000e f3 return
| 0x0000000f 6000 push1 0x0
| 0x00000011 36 calldatasize
| 0x00000012 81 dup2
| 0x00000013 80 dup1
| 0x00000014 37 calldatacopy
| 0x00000015 80 dup1
| 0x00000016 80 dup1
| 0x00000017 36 calldatasize
| 0x00000018 81 dup2
| 0x00000019 73bebebebebe. push20 0xbebebebe
| 0x0000002e 5a gas
| 0x0000002f f4 delegatecall
| 0x00000030 3d returndatasize
| 0x00000031 82 dup3
| 0x00000032 80 dup1
| 0x00000033 3e returndatacopy
| 0x00000034 15 iszero
| 0x00000035 602c push1 0x2c // note that this offset is post deployment the following jumpi "arrow" on the left was hand edited
,==< 0x00000037 57 jumpi
:| 0x00000038 3d returndatasize
:| 0x00000039 90 swap1
:| 0x0000003a f3 return
``-> 0x0000003b 5b jumpdest
0x0000003c 3d returndatasize
0x0000003d 90 swap1
0x0000003e fd revert
```
Disassembly of only the deployed contract bytecode is (straight from r2):
```
| 0x00000000 6000 push1 0x0
| 0x00000002 36 calldatasize
| 0x00000003 81 dup2
| 0x00000004 80 dup1
| 0x00000005 37 calldatacopy
| 0x00000006 80 dup1
| 0x00000007 80 dup1
| 0x00000008 36 calldatasize
| 0x00000009 81 dup2
| 0x0000000a 73bebebebebe. push20 0xbebebebe
| 0x0000001f 5a gas
| 0x00000020 f4 delegatecall
| 0x00000021 3d returndatasize
| 0x00000022 82 dup3
| 0x00000023 80 dup1
| 0x00000024 3e returndatacopy
| 0x00000025 15 iszero
| 0x00000026 602c push1 0x2c
| ,=< 0x00000028 57 jumpi
| | 0x00000029 3d returndatasize
| | 0x0000002a 90 swap1
| | 0x0000002b f3 return
| `-> 0x0000002c 5b jumpdest
| 0x0000002d 3d returndatasize
| 0x0000002e 90 swap1
\ 0x0000002f fd revert
```
The typical deployment pattern would be to deploy a Factory contract that can easily create clones. Here is the reference implementation of the clone-factory pattern:
```solidity
contract CloneFactory {
event CloneCreated(address indexed target, address clone);
function createClone(address target) internal returns (address result) {
bytes memory clone = hex"600034603b57603080600f833981f36000368180378080368173bebebebebebebebebebebebebebebebebebebebe5af43d82803e15602c573d90f35b3d90fd";
bytes20 targetBytes = bytes20(target);
for (uint i = 0; i < 20; i++) {
clone[26 + i] = targetBytes[i];
}
assembly {
let len := mload(clone)
let data := add(clone, 0x20)
result := create(0, data, len)
}
}
}
```
To utilize the above implementation, you would extend the contract like this:
```solidity
import "./Thing.sol";
import "../contracts/CloneFactory.sol";
contract ThingFactory is CloneFactory {
address public libraryAddress;
event ThingCreated(address newThingAddress, address libraryAddress);
constructor (address _libraryAddress) public {
libraryAddress = _libraryAddress;
}
function createThing(string _name, uint _value) public {
address clone = createClone(libraryAddress);
Thing(clone).init(_name, _value);
emit ThingCreated(clone, libraryAddress);
}
}
```
IMPORANT NOTE: When implementing, it is important to ensure that the master implementation contract cannot be 'initialized' and that it cannot in any way be selfdestructed.
Clones can be detected using the following contract
```solidity
contract ContractProbe {
function probe(address _addr) public view returns (bool isContract, address forwardedTo) {
bytes memory clone = hex"6000368180378080368173bebebebebebebebebebebebebebebebebebebebe5af43d82803e15602c573d90f35b3d90fd";
uint size;
bytes memory code;
assembly { //solhint-disable-line
size := extcodesize(_addr)
}
isContract = size > 0;
forwardedTo = _addr;
if (size <= 48 && size >= 44) {
bool matches = true;
uint i;
assembly { //solhint-disable-line
code := mload(0x40)
mstore(0x40, add(code, and(add(add(size, 0x20), 0x1f), not(0x1f))))
mstore(code, size)
extcodecopy(_addr, add(code, 0x20), 0, size)
}
for (i = 0; matches && i < 10; i++) {
matches = code[i] == clone[i];
}
for (i = 0; matches && i < 17; i++) {
if (i == 8) {
matches = code[code.length - i - 1] == byte(uint(clone[48 - i - 1]) - (48 - size));
} else {
matches = code[code.length - i - 1] == clone[48 - i - 1];
}
}
if (code[10] != byte(0x73 - (48 - size))) {
matches = false;
}
uint forwardedToBuffer;
if (matches) {
assembly { //solhint-disable-line
forwardedToBuffer := mload(add(code, 31))
}
forwardedToBuffer &= (0x1 << 20 * 8) - 1;
forwardedTo = address(forwardedToBuffer >> ((48 - size) * 8));
}
}
}
}
```
The ContractProbe contract is deployed on Kovan at `0x8b98e65e0e8bce0f71a2a22f3d2666591e4cc857` and on Mainnet at `0x0c953133aa046965b83a3de1215ed4285414537c`
## Copyright
Copyright and related rights waived via [CC0](https://creativecommons.org/publicdomain/zero/1.0/).