96 lines
2.6 KiB
Rust
96 lines
2.6 KiB
Rust
//! Various utilities for manipulating Ethereum related dat
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use ethabi::ethereum_types::H256;
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use tiny_keccak::{Hasher, Keccak};
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const PREFIX: &str = "\x19Ethereum Signed Message:\n";
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/// Hash a message according to EIP-191.
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///
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/// The data is a UTF-8 encoded string and will enveloped as follows:
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/// `"\x19Ethereum Signed Message:\n" + message.length + message` and hashed
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/// using keccak256.
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pub fn hash_message<S>(message: S) -> H256
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where
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S: AsRef<[u8]>,
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{
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let message = message.as_ref();
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let mut eth_message = format!("{}{}", PREFIX, message.len()).into_bytes();
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eth_message.extend_from_slice(message);
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keccak256(ð_message).into()
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}
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/// Compute the Keccak-256 hash of input bytes.
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// TODO: Add Solidity Keccak256 packing support
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pub fn keccak256<S>(bytes: S) -> [u8; 32]
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where
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S: AsRef<[u8]>,
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{
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let mut output = [0u8; 32];
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let mut hasher = Keccak::v256();
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hasher.update(bytes.as_ref());
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hasher.finalize(&mut output);
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output
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}
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/// Calculate the function selector as per the contract ABI specification. This
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/// is defined as the first 4 bytes of the Keccak256 hash of the function
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/// signature.
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pub fn id<S: AsRef<str>>(signature: S) -> [u8; 4] {
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let mut output = [0u8; 4];
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let mut hasher = Keccak::v256();
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hasher.update(signature.as_ref().as_bytes());
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hasher.finalize(&mut output);
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output
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}
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/// Serialize a type.
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///
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/// # Panics
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///
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/// If the type returns an error during serialization.
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pub fn serialize<T: serde::Serialize>(t: &T) -> serde_json::Value {
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serde_json::to_value(t).expect("Types never fail to serialize.")
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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// from https://emn178.github.io/online-tools/keccak_256.html
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fn test_keccak256() {
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assert_eq!(
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hex::encode(keccak256(b"hello")),
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"1c8aff950685c2ed4bc3174f3472287b56d9517b9c948127319a09a7a36deac8"
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);
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}
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// test vector taken from:
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// https://web3js.readthedocs.io/en/v1.2.2/web3-eth-accounts.html#hashmessage
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#[test]
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fn test_hash_message() {
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let hash = hash_message("Hello World");
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assert_eq!(
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hash,
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"a1de988600a42c4b4ab089b619297c17d53cffae5d5120d82d8a92d0bb3b78f2".parse().unwrap()
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);
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}
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#[test]
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fn simple_function_signature() {
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// test vector retrieved from
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// https://web3js.readthedocs.io/en/v1.2.4/web3-eth-abi.html#encodefunctionsignature
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assert_eq!(id("myMethod(uint256,string)"), [0x24, 0xee, 0x00, 0x97],);
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}
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#[test]
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fn revert_function_signature() {
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assert_eq!(id("Error(string)"), [0x08, 0xc3, 0x79, 0xa0]);
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}
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}
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