131 lines
3.6 KiB
JavaScript
131 lines
3.6 KiB
JavaScript
/* global self ReadableStream Response */
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self.addEventListener('install', () => {
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self.skipWaiting()
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})
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self.addEventListener('activate', event => {
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event.waitUntil(self.clients.claim())
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})
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const map = new Map()
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// This should be called once per download
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// Each event has a dataChannel that the data will be piped through
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self.onmessage = event => {
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// We send a heartbeat every x second to keep the
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// service worker alive if a transferable stream is not sent
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if (event.data === 'ping') {
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return
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}
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const data = event.data
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const downloadUrl = data.url || self.registration.scope + Math.random() + '/' + (typeof data === 'string' ? data : data.filename)
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const port = event.ports[0]
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const metadata = new Array(3) // [stream, data, port]
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metadata[1] = data
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metadata[2] = port
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// Note to self:
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// old streamsaver v1.2.0 might still use `readableStream`...
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// but v2.0.0 will always transfer the stream through MessageChannel #94
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if (event.data.readableStream) {
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metadata[0] = event.data.readableStream
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} else if (event.data.transferringReadable) {
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port.onmessage = evt => {
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port.onmessage = null
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metadata[0] = evt.data.readableStream
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}
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} else {
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metadata[0] = createStream(port)
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}
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map.set(downloadUrl, metadata)
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port.postMessage({ download: downloadUrl })
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}
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function createStream (port) {
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// ReadableStream is only supported by chrome 52
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return new ReadableStream({
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start (controller) {
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// When we receive data on the messageChannel, we write
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port.onmessage = ({ data }) => {
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if (data === 'end') {
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return controller.close()
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}
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if (data === 'abort') {
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controller.error('Aborted the download')
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return
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}
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controller.enqueue(data)
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}
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},
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cancel (reason) {
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console.log('user aborted', reason)
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port.postMessage({ abort: true })
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}
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})
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}
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self.onfetch = event => {
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const url = event.request.url
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// this only works for Firefox
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if (url.endsWith('/ping')) {
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return event.respondWith(new Response('pong'))
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}
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const hijacke = map.get(url)
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if (!hijacke) return null
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const [ stream, data, port ] = hijacke
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map.delete(url)
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// Not comfortable letting any user control all headers
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// so we only copy over the length & disposition
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const responseHeaders = new Headers({
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'Content-Type': 'application/octet-stream; charset=utf-8',
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// To be on the safe side, The link can be opened in a iframe.
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// but octet-stream should stop it.
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'Content-Security-Policy': "default-src 'none'",
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'X-Content-Security-Policy': "default-src 'none'",
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'X-WebKit-CSP': "default-src 'none'",
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'X-XSS-Protection': '1; mode=block',
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'Cross-Origin-Embedder-Policy': 'require-corp'
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})
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let headers = new Headers(data.headers || {})
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if (headers.has('Content-Length')) {
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responseHeaders.set('Content-Length', headers.get('Content-Length'))
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}
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if (headers.has('Content-Disposition')) {
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responseHeaders.set('Content-Disposition', headers.get('Content-Disposition'))
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}
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// data, data.filename and size should not be used anymore
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if (data.size) {
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console.warn('Depricated')
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responseHeaders.set('Content-Length', data.size)
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}
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let fileName = typeof data === 'string' ? data : data.filename
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if (fileName) {
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console.warn('Depricated')
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// Make filename RFC5987 compatible
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fileName = encodeURIComponent(fileName).replace(/['()]/g, escape).replace(/\*/g, '%2A')
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responseHeaders.set('Content-Disposition', "attachment; filename*=UTF-8''" + fileName)
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}
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event.respondWith(new Response(stream, { headers: responseHeaders }))
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port.postMessage({ debug: 'Download started' })
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}
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