fix(aria2): harden per-transfer DNS fallback (issue #35)

scripts/smoke-aria2-resolver.js

@@ -0,0 +1,232 @@
+#!/usr/bin/env node
+
+import crypto from 'node:crypto';
+import fs from 'node:fs';
+import http from 'node:http';
+import net from 'node:net';
+import os from 'node:os';
+import path from 'node:path';
+import { execFileSync, spawn } from 'node:child_process';
+import { fileURLToPath } from 'node:url';
+
+const repoRoot = path.resolve(path.dirname(fileURLToPath(import.meta.url)), '..');
+const arch = { x64: 'x86_64', arm64: 'aarch64' }[os.arch()];
+const platform = {
+  darwin: 'apple-darwin',
+  linux: 'unknown-linux-gnu',
+  win32: 'pc-windows-msvc',
+}[process.platform];
+if (!arch || !platform) {
+  throw new Error(`Unsupported host: ${os.arch()} / ${process.platform}`);
+}
+const targetTriple = `${arch}-${platform}`;
+const argumentIndex = process.argv.indexOf('--binary');
+const binaryPath = path.resolve(
+  argumentIndex >= 0
+    ? process.argv[argumentIndex + 1]
+    : path.join(
+        repoRoot,
+        'src-tauri',
+        'binaries',
+        `aria2c-${targetTriple}${process.platform === 'win32' ? '.exe' : ''}`,
+      ),
+);
+
+if (!fs.existsSync(binaryPath)) {
+  throw new Error(`Aria2 binary does not exist: ${binaryPath}`);
+}
+
+const wait = milliseconds => new Promise(resolve => setTimeout(resolve, milliseconds));
+
+async function availablePort() {
+  const server = net.createServer();
+  await new Promise((resolve, reject) => {
+    server.once('error', reject);
+    server.listen({ host: '127.0.0.1', port: 0 }, resolve);
+  });
+  const address = server.address();
+  const port = address && typeof address !== 'string' ? address.port : undefined;
+  await new Promise(resolve => server.close(resolve));
+  if (!port) throw new Error('Could not reserve a local port');
+  return port;
+}
+
+async function rpc(port, secret, method, params = []) {
+  const response = await fetch(`http://127.0.0.1:${port}/jsonrpc`, {
+    method: 'POST',
+    headers: { 'Content-Type': 'application/json' },
+    body: JSON.stringify({
+      jsonrpc: '2.0',
+      id: crypto.randomUUID(),
+      method,
+      params: [`token:${secret}`, ...params],
+    }),
+    signal: AbortSignal.timeout(3000),
+  });
+  const body = await response.json();
+  if (body.error) throw new Error(`${method}: ${JSON.stringify(body.error)}`);
+  if (!Object.hasOwn(body, 'result')) throw new Error(`${method}: response has no result`);
+  return body.result;
+}
+
+function childExited(child) {
+  return child.exitCode !== null || child.signalCode !== null;
+}
+
+async function waitForChildExit(child, timeoutMs = 3000) {
+  if (childExited(child)) return true;
+  return new Promise(resolve => {
+    let settled = false;
+    let timer;
+    const finish = result => {
+      if (settled) return;
+      settled = true;
+      clearTimeout(timer);
+      child.off('exit', onExit);
+      resolve(result);
+    };
+    const onExit = () => finish(true);
+    timer = setTimeout(() => finish(false), timeoutMs);
+    child.once('exit', onExit);
+    if (childExited(child)) finish(true);
+  });
+}
+
+async function waitForRpc(port, secret) {
+  const deadline = Date.now() + 10000;
+  let lastError;
+  while (Date.now() < deadline) {
+    try {
+      return await rpc(port, secret, 'aria2.getVersion');
+    } catch (error) {
+      lastError = error;
+      await wait(100);
+    }
+  }
+  throw new Error(`Aria2 RPC did not become ready: ${lastError?.message || 'unknown error'}`);
+}
+
+function bencode(value) {
+  if (Buffer.isBuffer(value)) return Buffer.concat([Buffer.from(`${value.length}:`), value]);
+  if (typeof value === 'string') return bencode(Buffer.from(value));
+  if (typeof value === 'number') return Buffer.from(`i${value}e`);
+  if (value && typeof value === 'object') {
+    const entries = Object.entries(value).sort(([left], [right]) => Buffer.compare(Buffer.from(left), Buffer.from(right)));
+    return Buffer.concat([
+      Buffer.from('d'),
+      ...entries.flatMap(([key, child]) => [bencode(key), bencode(child)]),
+      Buffer.from('e'),
+    ]);
+  }
+  throw new Error(`Unsupported bencode value: ${typeof value}`);
+}
+
+async function stop(child, port, secret) {
+  if (!child || childExited(child)) return;
+  try {
+    await rpc(port, secret, 'aria2.shutdown');
+  } catch {
+    // The process may already have exited.
+  }
+  let exited = await waitForChildExit(child);
+  if (!exited) {
+    if (process.platform === 'win32') {
+      try {
+        execFileSync('taskkill', ['/pid', String(child.pid), '/t', '/f'], {
+          stdio: 'ignore',
+          timeout: 3000,
+        });
+      } catch {
+        // The process may have exited between the timeout and taskkill.
+      }
+    } else {
+      child.kill('SIGTERM');
+    }
+    exited = await waitForChildExit(child);
+  }
+  if (!exited && process.platform !== 'win32') {
+    child.kill('SIGKILL');
+    exited = await waitForChildExit(child);
+  }
+  if (!exited) {
+    throw new Error(`Aria2 process ${child.pid} did not exit after forced cleanup`);
+  }
+}
+
+const tempRoot = fs.mkdtempSync(path.join(os.tmpdir(), 'firelink-aria2-resolver-'));
+const secret = `firelink-resolver-${crypto.randomUUID()}`;
+const rpcPort = await availablePort();
+const contentServer = http.createServer((_request, response) => {
+  response.writeHead(200, { 'content-length': '1' });
+  response.end('x');
+});
+await new Promise((resolve, reject) => {
+  contentServer.once('error', reject);
+  contentServer.listen({ host: '127.0.0.1', port: 0 }, resolve);
+});
+const contentPort = contentServer.address().port;
+const libraryPath = path.join(path.dirname(binaryPath), 'aria2-libs');
+const environment = fs.existsSync(libraryPath)
+  ? {
+      ...process.env,
+      OPENSSL_MODULES: libraryPath,
+      ...(process.platform === 'darwin' ? { DYLD_LIBRARY_PATH: libraryPath } : {}),
+    }
+  : process.env;
+const child = spawn(binaryPath, [
+  '--enable-rpc=true',
+  `--rpc-listen-port=${rpcPort}`,
+  '--rpc-listen-all=false',
+  `--rpc-secret=${secret}`,
+  `--dir=${tempRoot}`,
+  '--file-allocation=none',
+  '--enable-dht=false',
+  '--console-log-level=error',
+  '--quiet=true',
+], { env: environment, stdio: ['ignore', 'ignore', 'pipe'] });
+let stderr = '';
+child.stderr.on('data', chunk => { stderr += chunk.toString(); });
+
+try {
+  const version = await waitForRpc(rpcPort, secret);
+  const features = Array.isArray(version.enabledFeatures) ? version.enabledFeatures : [];
+  console.log(`[INFO] aria2 ${version.version || 'unknown'}; Async DNS: ${features.includes('Async DNS') ? 'supported' : 'not advertised'}`);
+
+  const uriResult = await rpc(rpcPort, secret, 'aria2.addUri', [[`http://127.0.0.1:${contentPort}/file`], {
+    'async-dns': 'false',
+    out: 'resolver-normal.bin',
+  }]);
+  const uriOptions = await rpc(rpcPort, secret, 'aria2.getOption', [uriResult]);
+  if (uriOptions['async-dns'] !== 'false') {
+    throw new Error(`aria2.addUri did not retain async-dns=false: ${JSON.stringify(uriOptions)}`);
+  }
+
+  const torrent = bencode({
+    info: {
+      length: 1,
+      name: 'resolver-torrent.bin',
+      pieces: Buffer.alloc(20),
+      'piece length': 16384,
+    },
+  }).toString('base64');
+  const torrentResult = await rpc(rpcPort, secret, 'aria2.addTorrent', [torrent, [], {
+    'async-dns': 'false',
+    dir: tempRoot,
+  }]);
+  const torrentOptions = await rpc(rpcPort, secret, 'aria2.getOption', [torrentResult]);
+  if (torrentOptions['async-dns'] !== 'false') {
+    throw new Error(`aria2.addTorrent did not retain async-dns=false: ${JSON.stringify(torrentOptions)}`);
+  }
+
+  console.log('[PASS] Aria2 retained system-resolver mode for normal and Torrent transfers');
+} catch (error) {
+  const detail = stderr.trim();
+  throw new Error(`${error.message}${detail ? `\n${detail}` : ''}`);
+} finally {
+  try {
+    await stop(child, rpcPort, secret);
+  } finally {
+    await new Promise(resolve => contentServer.close(resolve));
+    fs.rmSync(tempRoot, { recursive: true, force: true });
+  }
+}