75 lines
3.7 KiB
TypeScript
75 lines
3.7 KiB
TypeScript
/** Local Web document and authenticated HTTP forwarding for the application window. */
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import { readFile } from 'node:fs/promises'
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import { extname, resolve, sep } from 'node:path'
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const MIME: Readonly<Record<string, string>> = {
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'.html': 'text/html; charset=utf-8', '.js': 'text/javascript; charset=utf-8',
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'.css': 'text/css; charset=utf-8', '.svg': 'image/svg+xml', '.json': 'application/json',
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'.woff2': 'font/woff2', '.png': 'image/png', '.ico': 'image/x-icon',
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}
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const BOOT = '<script>globalThis.__DSH_BOOT_READY__ = Promise.withResolvers()</script>'
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/**
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* Read an application-owned static asset; the index waits for asynchronous Host injections.
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* @param request - Local application request.
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* @param root - Packaged Web dist directory.
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* @returns Static response, or a missing/invalid path response.
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*/
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export async function serveWebDocument(request: Request, root: string): Promise<Response> {
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if (!['GET', 'HEAD'].includes(request.method)) return new Response(null, { status: 405 })
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const url = new URL(request.url)
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let pathname: string
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try { pathname = decodeURIComponent(url.pathname) } catch { return new Response(null, { status: 400 }) }
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const target = resolve(root, '.' + (pathname === '/' ? '/index.html' : pathname))
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const directory = resolve(root)
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if (!target.startsWith(directory + sep)) return new Response(null, { status: 403 })
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let body: Buffer
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try { body = await readFile(target) } catch (error) {
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if ((error as NodeJS.ErrnoException).code === 'ENOENT') return new Response(null, { status: 404 })
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throw error
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}
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const content = pathname === '/' || pathname === '/index.html'
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? body.toString().replace('<head>', '<head>' + BOOT) : new Uint8Array(body)
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return new Response(request.method === 'HEAD' ? null : content, {
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headers: { 'content-type': MIME[extname(target)] ?? 'application/octet-stream' },
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})
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}
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/**
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* Exchange the Host launch URL for an authority-bound browser cookie.
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* @param url - Authenticated URL reported by the owned Host process.
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* @returns Cookie header for requests forwarded to that Host.
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*/
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export async function authenticateWebHost(url: string): Promise<string> {
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const response = await fetch(url, { redirect: 'manual' })
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const cookie = response.headers.get('set-cookie')
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await response.body?.cancel()
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if (response.status !== 303 || cookie === null) throw new Error('Desktop Host authentication failed')
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const end = cookie.indexOf(';')
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return end < 0 ? cookie : cookie.slice(0, end)
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}
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/**
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* Forward local application requests to its authenticated Host, preserving streaming and cancellation.
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* @param request - Request from the application origin.
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* @param host - Owned Host URL.
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* @param cookie - Host-issued authentication cookie.
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* @returns Host response without network-only encoding headers.
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*/
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export async function forwardWebRequest(request: Request, host: string, cookie: string): Promise<Response> {
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const source = new URL(request.url)
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const origin = request.headers.get('origin')
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if (origin !== null && origin !== 'dsh-app://app') return new Response(null, { status: 403 })
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const target = new URL(host)
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target.pathname = source.pathname
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target.search = source.search
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const headers = new Headers(request.headers)
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for (const name of ['host', 'origin', 'cookie', 'sec-fetch-site']) headers.delete(name)
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headers.set('cookie', cookie)
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const init = { method: request.method, headers, body: request.body, signal: request.signal, duplex: 'half', redirect: 'manual' as const }
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const response = await fetch(target, init)
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const outgoing = new Headers(response.headers)
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for (const name of ['content-encoding', 'content-length', 'set-cookie']) outgoing.delete(name)
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return new Response(response.body, { status: response.status, headers: outgoing })
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}
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