116 lines
3.5 KiB
TypeScript
116 lines
3.5 KiB
TypeScript
// 浏览器端 WebTorrent（WebRTC）：把 P2P 流量放到用户自己的设备，
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// 绕开 Vercel / Cloudflare 等 Serverless 不支持 UDP/DHT 的限制。
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// 服务端仍保留非 P2P 的缓存服务兜底；这里是真正的 P2P 取数据路径。
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// 浏览器只支持 WebRTC 节点，需要走 wss:// 的 tracker 才能发现对端
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const WS_TRACKERS = [
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'wss://tracker.openwebtorrent.com',
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'wss://tracker.btorrent.xyz',
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'wss://tracker.webtorrent.dev'
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]
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function normPath(p: string): string {
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return p.replace(/\\/g, '/').replace(/^\.\//, '')
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}
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function withWsTrackers(magnet: string): string {
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const existing = new Set<string>()
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for (const m of magnet.matchAll(/[?&]tr=([^&]+)/g)) {
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try {
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existing.add(decodeURIComponent(m[1]))
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} catch {
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/* ignore */
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}
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}
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const add = WS_TRACKERS.filter((t) => !existing.has(t))
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if (!add.length) return magnet
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const sep = magnet.includes('?') ? '&' : '?'
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return magnet + sep + add.map((t) => `tr=${encodeURIComponent(t)}`).join('&')
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}
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let wtPromise: Promise<any> | null = null
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function loadWebTorrent(): Promise<any> {
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if (!wtPromise) {
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// 仅在浏览器运行时按需加载，Vite 会将其单独拆包；服务端不会执行到此处
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wtPromise = import('webtorrent').then((m) => (m as any).default || m)
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}
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return wtPromise
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}
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function waitForMetadata(torrent: any, timeoutMs: number): Promise<void> {
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return new Promise((resolve, reject) => {
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if (torrent.metadata || torrent.ready) return resolve()
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const timer = setTimeout(
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() => reject(new Error('浏览器 P2P 获取元数据超时，可能该种子没有 WebRTC 节点')),
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timeoutMs
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)
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const done = () => {
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clearTimeout(timer)
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resolve()
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}
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torrent.on('metadata', done)
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torrent.on('ready', done)
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torrent.on('error', (e: Error) => {
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clearTimeout(timer)
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reject(e)
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})
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})
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}
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export async function resolveMetadataClient(
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magnet: string,
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timeoutMs = 30000
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): Promise<{ name: string; files: { path: string; length: number }[]; size: number }> {
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const WebTorrent = await loadWebTorrent()
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const client = new WebTorrent()
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try {
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const torrent = client.add(withWsTrackers(magnet))
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await waitForMetadata(torrent, timeoutMs)
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const files = (torrent.files || []).map((f: any) => ({
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path: normPath(String(f.path || f.name || '')),
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length: Number(f.length) || 0
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}))
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if (!files.length) throw new Error('已连上节点，但对方没有返回任何文件信息')
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return { name: String(torrent.name || ''), files, size: files.reduce((s, f) => s + f.length, 0) }
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} finally {
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try {
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client.destroy()
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} catch {
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/* ignore */
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}
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}
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}
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export async function readFileBytesClient(
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magnet: string,
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filePath: string,
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timeoutMs = 25000
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): Promise<ArrayBuffer> {
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const WebTorrent = await loadWebTorrent()
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const client = new WebTorrent()
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try {
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const torrent = client.add(withWsTrackers(magnet))
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await waitForMetadata(torrent, timeoutMs)
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const target = (torrent.files || []).find(
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(f: any) => normPath(String(f.path || f.name || '')) === normPath(filePath)
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)
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if (!target) throw new Error('这个种子里没有该文件，文件清单可能已过期')
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return await target.arrayBuffer()
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} finally {
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try {
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client.destroy()
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} catch {
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/* ignore */
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}
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}
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}
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export async function isClientWebTorrentAvailable(): Promise<boolean> {
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try {
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await loadWebTorrent()
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return true
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} catch {
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return false
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}
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}
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