feat: add fn parse_checksummed

[izayl]

Motivation

as ethers-rs provide to_checksum function, but there not provide a way to verify a checksum-like address.
so I add a utilities function to verify a checksum address is valid.

Solution

PR Checklist

• Added Tests
• Added Documentation
• Breaking changes

[mattsse]

this should be false, no?

[izayl]

you're right, I have fixed it

[mattsse]

don't love the name,
also not a fan of the to_checksum function, should have been named to_checksum_address
but, to keep it consistent, this is fine I guess.

[izayl]

maybe check_address_checksum?
ref: https://github.com/web3/web3.js/blob/aaf26c8806bc9fb60cf6dcb6658104963c6c7fc7/packages/web3-utils/src/Utils.js#L140

[mattsse]

smol style nit

[mattsse]

use

if let Ok() {
let checksum_addr = to_checksum(&address.unwrap(), chain_id);

    return checksum_addr.strip_prefix("0x").unwrap_or(&checksum_addr) == addr

}
false

[izayl]

Done

[prestwich]

API change

[prestwich]

why return a bool instead of the address? We're doing the parsing work regardless, and the user can always call is_some if they need a bool

basically shouldn't this be parse_checksummed instead

[izayl]

like this?

/// Returns a `Result<Address>`: `Ok(Address)` if addr is checksummed, `Err()` otherwise
pub fn parse_checksummed(addr: &str, chain_id: Option<u8>) -> Result<Address>

[prestwich]

function signature is awesome 👌

I'd write docs similar to this:

/// Parses an [EIP-1191](https://eips.ethereum.org/EIPS/eip-1191) checksum address. Returns `Ok(address)` if the checksummed address is valid, `Err()` otherwise. If `chain_id` is `None`, falls back to [EIP-55](https://eips.ethereum.org/EIPS/eip-55) address checksum method

[izayl]

@prestwich refactored, pls check it

[prestwich]

rather than returning text too long, I think we can do the following

1. add a hex error to the ConversionError enum

enum ConversionError { 
    ...,
    /// Hex error, usually from address parsing
    #[error(transparent)]
    FromHexError(#[from]hex::FromHexError)
}

2. change this function to use a ?

        let addr: Address = addr.strip_prefix("0x").unwrap_or(addr).parse()?
        if checksum_addr.strip_prefix("0x").unwrap_or(&checksum_addr) == addr {
            return Ok(address)
        } else {
            return Err(ConversionError::InvalidAddressChecksum)
        }

[izayl]

the FromHexError is from rustc_hex crate, should I add a it?

[izayl]

source: https://github.com/paritytech/parity-common/blob/master/fixed-hash/src/hash.rs#L568-L593

[prestwich]

leave it to parity to make our lives more complicated 🤣 🙄

I think you should be able to make it work as follows:

1. reference the fully qualified associated type <Address as std::str::FromStr>::Err in the enum variant
2. instead of doing a #[from] in the error variant, use map_err to convert

// variant specifies that it takes "whatever error the `parse()` implementation says is the error"
FromHexError(<Address as std::str::FromStr>::Err)

// map err on the first line of the function
let addr: Address = addr.strip_prefix("0x").unwrap_or(addr).parse().map_err(ConversionError::FromHexError)?;

[prestwich]

sorry this is a pain. if it gets too much let me know and i'll do the tidying

[izayl]

@prestwich I've add this FromHexError

[prestwich]

changes are good. 1 more small ergonomics tweak 🙏

[prestwich]

Approving, pending CI run completion. Thanks for the contribution!