sevm/4byte/index.js

A Symbolic Ethereum Virtual Machine (EVM) bytecode decompiler & analyzer library & CLI

/* eslint-env node */
/* eslint-disable @typescript-eslint/no-var-requires */

const sevm = require('sevm');

sevm.Contract.prototype.patch = async function (/** @type {Partial<import('.').Lookup>} */lookup = {}) {
    const keys = Object.keys;
    /** @type {(selector: string) => string} */
    const hex = selector => '0x' + selector;
    const functions = [...keys(this.functions), ...keys(this.reverts)].map(hex).join(',');
    const events = keys(this.events).map(hex).join(',');

    if (!lookup.function || !lookup.event) {
        const url = `https://api.openchain.xyz/signature-database/v1/lookup?function=${functions}&event=${events}`;
        const resp = await fetch(url);

        if (!resp.ok) {
            throw new Error(`Failed to fetch signatures from api.openchain.xyz, url: ${url}`);
        }

        /** @typedef {{ [hash: string]: {name: string, filtered: boolean}[] | null }} HashesResponse */
        const { result } = /** @type {{result: { function: HashesResponse, event: HashesResponse }}} */ (await resp.json());

        /**
         * @param {HashesResponse} hashes 
         * @returns {{ [hash: string]: string[] }}
         */
        const mapHashes = hashes => Object.fromEntries(
            Object.entries(hashes).map(([hash, matches]) => [hash, matches?.map(({ name }) => name) ?? []])
        );

        lookup.function = mapHashes(result.function);
        lookup.event = mapHashes(result.event);
    }

    for (let [selector, fn] of Object.entries(this.functions)) {
        selector = '0x' + selector;
        if (selector in lookup.function)
            fn.label = lookup.function[selector][0];
    }

    for (let [topic, event] of Object.entries(this.events)) {
        topic = '0x' + topic;
        if (topic in lookup.event)
            event.sig = lookup.event[topic][0];
    }

    for (let [selector, decl] of Object.entries(this.reverts)) {
        selector = '0x' + selector;
        if (selector in lookup.function)
            decl.sig = lookup.function[selector][0];
    }

    return this;
};

module.exports = sevm;