mirror of https://github.com/status-im/EIPs.git
127 lines
10 KiB
Markdown
127 lines
10 KiB
Markdown
---
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eip: 1167
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title: Minimal Proxy Contract
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author: Peter Murray (@yarrumretep), Nate Welch (@flygoing), Joe Messerman (@JAMesserman)
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discussions-to: https://github.com/optionality/clone-factory/issues/10
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status: Final
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type: Standards Track
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category: ERC
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created: 2018-06-22
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requires: 211
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---
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<!--You can leave these HTML comments in your merged EIP and delete the visible duplicate text guides, they will not appear and may be helpful to refer to if you edit it again. This is the suggested template for new EIPs. Note that an EIP number will be assigned by an editor. When opening a pull request to submit your EIP, please use an abbreviated title in the filename, `eip-draft_title_abbrev.md`. The title should be 44 characters or less.-->
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## Simple Summary
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<!--"If you can't explain it simply, you don't understand it well enough." Provide a simplified and layman-accessible explanation of the EIP.-->
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To simply and cheaply clone contract functionality in an immutable way, this standard specifies a minimal bytecode implementation that delegates all calls to a known, fixed address.
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## Abstract
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<!--A short (~200 word) description of the technical issue being addressed.-->
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By standardizing on a known minimal bytecode redirect implementation, this standard allows 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).
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## Motivation
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<!--The motivation is critical for EIPs that want to change the Ethereum protocol. It should clearly explain why the existing protocol specification is inadequate to address the problem that the EIP solves. EIP submissions without sufficient motivation may be rejected outright.-->
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This standard supports use-cases wherein it is desireable to clone exact contract functionality with a minimum of side effects (e.g. memory slot stomping) and with low gas cost deployment of duplicate proxies.
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## Specification
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<!--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)).-->
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The exact bytecode of the standard clone contract is this: `363d3d373d3d3d363d73bebebebebebebebebebebebebebebebebebebebe5af43d82803e903d91602b57fd5bf3` wherein the bytes at indices 10 - 29 (inclusive) are replaced with the 20 byte address of the master functionality contract.
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A reference implementation of this can be found at the [optionality/clone-factory](https://github.com/optionality/clone-factory) github repo.
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## Rationale
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<!--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.-->
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The goals of this effort have been the following:
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- inexpensive deployment (low gas to deploy clones)
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- support clone initialization in creation transaction (through factory contract model)
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- simple clone bytecode to encourage directly bytecode interrogation (see CloneProbe.sol in the clone-factory project)
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- dependable, locked-down behavior - this is not designed to handle upgradability, nor should it as the representation we are seeking is stronger.
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- small operational overhead - adds a single call cost to each call
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- handles error return bubbling for revert messages
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## Backwards Compatibility
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<!--All EIPs that introduce backwards incompatibilities must include a section describing these incompatibilities and their severity. The EIP must explain how the author proposes to deal with these incompatibilities. EIP submissions without a sufficient backwards compatibility treatise may be rejected outright.-->
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There are no backwards compatibility issues. There may be some systems that are using earlier versions of the proxy contract bytecode. They will not be compliant with this standard.
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## Test Cases
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<!--Test cases for an implementation are mandatory for EIPs that are affecting consensus changes. Other EIPs can choose to include links to test cases if applicable.-->
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Test cases include:
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- invocation with no arguments
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- invocation with arguments
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- invocation with fixed length return values
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- invocation with variable length return values
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- invocation with revert (confirming reverted payload is transferred)
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Tests for these cases are included in the reference implementation project.
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## Implementation
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<!--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.-->
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Deployment bytecode is not included in this specification. One approach is defined in the proxy-contract reference implementation.
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### Standard Proxy
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The disassembly of the standard deployed proxy contract code (from r2 and edited to include stack visualization)
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```
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| 0x00000000 36 calldatasize cds
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| 0x00000001 3d returndatasize 0 cds
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| 0x00000002 3d returndatasize 0 0 cds
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| 0x00000003 37 calldatacopy
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| 0x00000004 3d returndatasize 0
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| 0x00000005 3d returndatasize 0 0
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| 0x00000006 3d returndatasize 0 0 0
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| 0x00000007 36 calldatasize cds 0 0 0
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| 0x00000008 3d returndatasize 0 cds 0 0 0
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| 0x00000009 73bebebebebe. push20 0xbebebebe 0xbebe 0 cds 0 0 0
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| 0x0000001e 5a gas gas 0xbebe 0 cds 0 0 0
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| 0x0000001f f4 delegatecall suc 0
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| 0x00000020 3d returndatasize rds suc 0
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| 0x00000021 82 dup3 0 rds suc 0
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| 0x00000022 80 dup1 0 0 rds suc 0
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| 0x00000023 3e returndatacopy suc 0
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| 0x00000024 90 swap1 0 suc
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| 0x00000025 3d returndatasize rds 0 suc
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| 0x00000026 91 swap2 suc 0 rds
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| 0x00000027 602b push1 0x2b 0x2b suc 0 rds
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| ,=< 0x00000029 57 jumpi 0 rds
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| | 0x0000002a fd revert
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| `-> 0x0000002b 5b jumpdest 0 rds
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\ 0x0000002c f3 return
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```
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NOTE: as an effort to reduce gas costs as much as possible, the above bytecode depends on EIP-211 specification that `returndatasize` returns zero prior to any calls within the call-frame. `returndatasize` uses 1 less gas than `dup*`.
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### Vanity Address Optimization
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Proxy deployment can be further optimized by installing the master contract at a vanity contract deployment address with leading zero-bytes. By generating a master contract vanity address that includes Z leading 0 bytes in its address, you can shorten the proxy bytecode by replacing the `push20` opcode with `pushN` (where N is 20 - Z) followed by the N non-zero address bytes. The revert jump address is decremented by Z in this case. Here is an example where Z = 4:
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```
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| 0x00000000 36 calldatasize cds
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| 0x00000001 3d returndatasize 0 cds
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| 0x00000002 3d returndatasize 0 0 cds
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| 0x00000003 37 calldatacopy
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| 0x00000004 3d returndatasize 0
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| 0x00000005 3d returndatasize 0 0
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| 0x00000006 3d returndatasize 0 0 0
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| 0x00000007 36 calldatasize cds 0 0 0
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| 0x00000008 3d returndatasize 0 cds 0 0 0
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| 0x00000009 6fbebebebebe. push16 0xbebebebe 0xbebe 0 cds 0 0 0
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| 0x0000001a 5a gas gas 0xbebe 0 cds 0 0 0
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| 0x0000001b f4 delegatecall suc 0
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| 0x0000001c 3d returndatasize rds suc 0
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| 0x0000001d 82 dup3 0 rds suc 0
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| 0x0000001e 80 dup1 0 0 rds suc 0
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| 0x0000001f 3e returndatacopy suc 0
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| 0x00000020 90 swap1 0 suc
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| 0x00000021 3d returndatasize rds 0 suc
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| 0x00000022 91 swap2 suc 0 rds
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| 0x00000023 6027 push1 0x27 0x27 suc 0 rds
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| ,=< 0x00000025 57 jumpi 0 rds
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| | 0x00000026 fd revert
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| `-> 0x00000027 5b jumpdest 0 rds
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\ 0x00000028 f3 return
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```
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This saves 4 bytes of proxy contract size (savings on each deployment) and has zero impact on runtime gas costs.
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## Copyright
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Copyright and related rights waived via [CC0](https://creativecommons.org/publicdomain/zero/1.0/).
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