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67 lines
1.7 KiB
67 lines
1.7 KiB
const ethSigUtil = require('eth-sig-util');
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const keccak256 = require('keccak256');
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const EIP712Domain = [
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{ name: 'name', type: 'string' },
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{ name: 'version', type: 'string' },
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{ name: 'chainId', type: 'uint256' },
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{ name: 'verifyingContract', type: 'address' },
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{ name: 'salt', type: 'bytes32' },
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];
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const Permit = [
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{ name: 'owner', type: 'address' },
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{ name: 'spender', type: 'address' },
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{ name: 'value', type: 'uint256' },
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{ name: 'nonce', type: 'uint256' },
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{ name: 'deadline', type: 'uint256' },
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];
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function bufferToHexString(buffer) {
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return '0x' + buffer.toString('hex');
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}
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function hexStringToBuffer(hexstr) {
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return Buffer.from(hexstr.replace(/^0x/, ''), 'hex');
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}
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async function getDomain(contract) {
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const { fields, name, version, chainId, verifyingContract, salt, extensions } = await contract.eip712Domain();
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if (extensions.length > 0) {
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throw Error('Extensions not implemented');
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}
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const domain = { name, version, chainId, verifyingContract, salt };
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for (const [i, { name }] of EIP712Domain.entries()) {
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if (!(fields & (1 << i))) {
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delete domain[name];
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}
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}
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return domain;
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}
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function domainType(domain) {
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return EIP712Domain.filter(({ name }) => domain[name] !== undefined);
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}
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function domainSeparator(domain) {
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return bufferToHexString(
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ethSigUtil.TypedDataUtils.hashStruct('EIP712Domain', domain, { EIP712Domain: domainType(domain) }),
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);
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}
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function hashTypedData(domain, structHash) {
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return bufferToHexString(
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keccak256(Buffer.concat(['0x1901', domainSeparator(domain), structHash].map(str => hexStringToBuffer(str)))),
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);
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}
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module.exports = {
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Permit,
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getDomain,
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domainType,
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domainSeparator,
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hashTypedData,
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};
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