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feat(npm): verify SHA-256 of downloaded binary against checksums.txt #63

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feat(npm): verify SHA-256 of downloaded binary against checksums.txt #63

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46 changes: 46 additions & 0 deletions npm/postinstall.js
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Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,7 @@
const fs = require('fs');
const path = require('path');
const https = require('https');
const crypto = require('crypto');
const zlib = require('zlib');
const { pipeline } = require('stream');
const { promisify } = require('util');
Expand Down Expand Up @@ -41,6 +42,8 @@ if (!target) {
}

const url = `https://github.com/optiqor/optiqor-cli/releases/download/v${VERSION}/optiqor_${VERSION}_${target}.tar.gz`;
const checksumsUrl = `https://github.com/optiqor/optiqor-cli/releases/download/v${VERSION}/checksums.txt`;
const archiveName = `optiqor_${VERSION}_${target}.tar.gz`;
const vendorDir = path.join(__dirname, '..', 'vendor');
fs.mkdirSync(vendorDir, { recursive: true });

Expand All @@ -63,11 +66,54 @@ const get = (u) =>

const pipelineP = promisify(pipeline);

// Returns the hex digest for archiveName from GoReleaser checksums.txt.
const expectedDigest = (checksumsText) => {
for (const line of checksumsText.split(/\r?\n/)) {
const [digest, name] = line.trim().split(/\s+/);
if (name !== archiveName) continue;
return /^[0-9a-f]{64}$/i.test(digest) ? digest.toLowerCase() : null;
}
return null;
};

const sha256Of = (file) =>
crypto.createHash('sha256').update(fs.readFileSync(file)).digest('hex');

const fetchText = async (u) => {
const res = await get(u);
let body = '';
res.setEncoding('utf8');
for await (const chunk of res) body += chunk;
return body;
};

(async () => {
try {
console.log(`optiqor: downloading binary for ${key}...`);
const res = await get(url);
await pipelineP(res, fs.createWriteStream(tarballPath));

// Verify the SHA-256 digest against the release's checksums.txt
// before extracting, so a MITM'd or hijacked release asset never
// executes on the user's machine.
const checksumsText = await fetchText(checksumsUrl);
const digest = expectedDigest(checksumsText);
if (!digest) {
fs.unlinkSync(tarballPath);
console.error(`optiqor: ${archiveName} missing from ${checksumsUrl}`);
console.error('optiqor: refusing to install an unverified binary.');
process.exit(1);
}
const actual = sha256Of(tarballPath);
if (actual !== digest) {
fs.unlinkSync(tarballPath);
console.error(`optiqor: checksum mismatch for ${archiveName}`);
console.error(`optiqor: expected ${digest}`);
console.error(`optiqor: actual ${actual}`);
console.error('optiqor: refusing to install a tampered binary.');
process.exit(1);
}

// tar -xzf using system tar (avoids adding tar npm dep).
execFileSync('tar', ['-xzf', tarballPath, '-C', vendorDir], { stdio: 'inherit' });
fs.unlinkSync(tarballPath);
Expand Down