@ledgerhq/hw-app-eth/lib-es/services/ledger/erc20.js

Ledger Hardware Wallet Ethereum Application API

import axios from "axios";
import { log } from "@ledgerhq/logs";
import { signatures as signaturesByChainId } from "@ledgerhq/cryptoassets-evm-signatures/data/evm/index";
import { getLoadConfig } from "./loadConfig";
const asContractAddress = (addr) => {
    const a = addr.toLowerCase();
    return a.startsWith("0x") ? a : "0x" + a;
};
export const findERC20SignaturesInfo = async (userLoadConfig, chainId) => {
    const { cryptoassetsBaseURL } = getLoadConfig(userLoadConfig);
    if (!cryptoassetsBaseURL)
        return null;
    const url = `${cryptoassetsBaseURL}/evm/${chainId}/erc20-signatures.json`;
    const blob = await axios
        .get(url)
        .then(({ data }) => {
        if (!data || typeof data !== "string") {
            throw new Error(`ERC20 signatures for chainId ${chainId} file is malformed ${url}`);
        }
        return data;
    })
        .catch(e => {
        log("error", "could not fetch from " + url + ": " + String(e));
        return null;
    });
    return blob;
};
/**
 * Retrieve the token information by a given contract address if any
 */
export const byContractAddressAndChainId = (contract, chainId, erc20SignaturesBlob) => {
    // If we are able to fetch data from s3 bucket that contains dynamic CAL
    if (erc20SignaturesBlob) {
        try {
            return parse(erc20SignaturesBlob).byContractAndChainId(asContractAddress(contract), chainId);
        }
        catch (e) {
            return get(chainId)?.byContractAndChainId(asContractAddress(contract), chainId);
        }
    }
    // the static fallback when dynamic cal is not provided
    return get(chainId)?.byContractAndChainId(asContractAddress(contract), chainId);
};
const parse = (erc20SignaturesBlob) => {
    const buf = Buffer.from(erc20SignaturesBlob, "base64");
    const map = {};
    const entries = [];
    let i = 0;
    while (i < buf.length) {
        const length = buf.readUInt32BE(i);
        i += 4;
        const item = buf.slice(i, i + length);
        let j = 0;
        const tickerLength = item.readUInt8(j);
        j += 1;
        const ticker = item.slice(j, j + tickerLength).toString("ascii");
        j += tickerLength;
        const contractAddress = asContractAddress(item.slice(j, j + 20).toString("hex"));
        j += 20;
        const decimals = item.readUInt32BE(j);
        j += 4;
        const chainId = item.readUInt32BE(j);
        j += 4;
        const signature = item.slice(j);
        const entry = {
            ticker,
            contractAddress,
            decimals,
            chainId,
            signature,
            data: item,
        };
        entries.push(entry);
        map[String(chainId) + ":" + contractAddress] = entry;
        i += length;
    }
    return {
        list: () => entries,
        byContractAndChainId: (contractAddress, chainId) => map[String(chainId) + ":" + contractAddress],
    };
};
// this internal get() will lazy load and cache the data from the erc20 data blob
const get = (() => {
    const cache = {};
    return chainId => {
        if (cache[chainId])
            return cache[chainId];
        const signatureBlob = signaturesByChainId[chainId];
        if (!signatureBlob)
            return null;
        const api = parse(signatureBlob);
        cache[chainId] = api;
        return api;
    };
})();
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