check-ethereum-scanner
Version:
Safety checks for new Ethereum tokens
120 lines (111 loc) • 3.17 kB
JavaScript
/*
ISC License
Copyright (c) 2019, Pierre-Louis Despaigne
Permission to use, copy, modify, and/or distribute this software for any
purpose with or without fee is hereby granted, provided that the above
copyright notice and this permission notice appear in all copies.
THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
const CID = require('cids');
const multiH = require('multihashes');
/**
* Convert an hexadecimal string to a Buffer, the string can start with or without '0x'
* @param {string} hex an hexadecimal value
* @return {Buffer} the resulting Buffer
*/
const hexStringToBuffer = (hex) => {
let prefix = hex.slice(0, 2);
let value = hex.slice(2);
let res = '';
if (prefix === '0x') res = value;
else res = hex;
return multiH.fromHexString(res);
}
/**
* list of known encoding,
* encoding should be a function that takes a `string` input,
* and return a `Buffer` result
*/
const encodes = {
/**
* @param {string} value
* @return {Buffer}
*/
swarm: (value) => {
const multihash = multiH.encode(hexStringToBuffer(value), 'keccak-256');
return new CID(1, 'swarm-manifest', multihash).buffer;
},
/**
* @param {string} value
* @return {Buffer}
*/
ipfs: (value) => {
const multihash = multiH.fromB58String(value);
return new CID(1, 'dag-pb', multihash).buffer;
},
/**
* @param {string} value
* @return {Buffer}
*/
utf8: (value) => {
return Buffer.from(value, 'utf8');
},
};
/**
* list of known decoding,
* decoding should be a function that takes a `Buffer` input,
* and return a `string` result
*/
const decodes = {
/**
* @param {Buffer} value
*/
hexMultiHash: (value) => {
const cid = new CID(value);
return multiH.decode(cid.multihash).digest.toString('hex');
},
/**
* @param {Buffer} value
*/
b58MultiHash: (value) => {
const cid = new CID(value);
return multiH.toB58String(cid.multihash);
},
/**
* @param {Buffer} value
*/
utf8: (value) => {
return value.toString('utf8');
},
};
/**
* list of known encoding/decoding for a given codec,
* `encode` should be chosen among the `encodes` functions
* `decode` should be chosen among the `decodes` functions
*/
const profiles = {
'swarm-ns': {
encode: encodes.swarm,
decode: decodes.hexMultiHash,
},
'ipfs-ns': {
encode: encodes.ipfs,
decode: decodes.b58MultiHash,
},
'ipns-ns': {
encode: encodes.ipfs,
decode: decodes.b58MultiHash,
},
'default': {
encode: encodes.utf8,
decode: decodes.utf8,
},
};
exports.hexStringToBuffer = hexStringToBuffer;
exports.profiles = profiles;