Created
August 21, 2024 17:20
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ts image size handler
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| import http from 'node:http' | |
| import https from 'node:https' | |
| import sizeOf from 'image-size' | |
| const MAX_REDIRECTS = Number.parseInt( | |
| process.env.IMGMETA_MAX_REDIRECTS || '10', | |
| 10, | |
| ) | |
| const ALLOWED_DOMAINS = process.env.IMGMETA_ALLOWED_DOMAINS || '*' | |
| const TIMEOUT = | |
| Number.parseInt(process.env.IMGMETA_FETCH_TIMEOUT || '10', 10) * 1000 | |
| const _getPathname = (url: string): string => { | |
| const pathname = new URL(url).pathname | |
| return pathname.startsWith('/') ? pathname.slice(1) : pathname | |
| } | |
| const _parseUrl = (pathname: string): string | null => { | |
| if (pathname === '') { | |
| return null | |
| } | |
| try { | |
| const path = | |
| pathname.startsWith('http://') || pathname.startsWith('https://') | |
| ? pathname | |
| : atob(pathname) | |
| try { | |
| const url = new URL(path) | |
| if (url.protocol !== 'http:' && url.protocol !== 'https:') { | |
| return null | |
| } | |
| return url.href | |
| } catch { | |
| return null | |
| } | |
| } catch { | |
| return null | |
| } | |
| } | |
| const _isDomainAllowed = (imageUrl: string): boolean => { | |
| if (ALLOWED_DOMAINS === '*') { | |
| return true | |
| } | |
| const allowedDomains = process.env.IMGMETA_ALLOWED_DOMAINS?.split(',') || [] | |
| return allowedDomains.some( | |
| allowed => | |
| imageUrl.startsWith(allowed) || | |
| imageUrl.startsWith(`https://${allowed}`) || | |
| imageUrl.startsWith(`http://${allowed}`), | |
| ) | |
| } | |
| const _getImage = async ( | |
| url: string, | |
| redirects = MAX_REDIRECTS, | |
| ): Promise<Uint8Array> => | |
| new Promise((resolve, reject) => { | |
| const getter = url.startsWith('https') ? https.get : http.get | |
| getter(url, { timeout: TIMEOUT }, res => { | |
| const { statusCode } = res | |
| if (statusCode && statusCode >= 300 && statusCode < 400) { | |
| if (redirects <= 0) { | |
| reject(new Error('Too many redirects')) | |
| res.resume() | |
| return | |
| } | |
| const location = res.headers.location | |
| if (!location) { | |
| reject(new Error('No location header')) | |
| res.resume() | |
| return | |
| } | |
| return resolve(_getImage(location, redirects - 1)) | |
| } | |
| let data: Uint8Array = new Uint8Array() | |
| const limit = 512 // kb | |
| let size = 0 | |
| res.on('data', (chunk: Uint8Array) => { | |
| size += chunk.length | |
| if (size > limit * 1024) { | |
| return resolve(data) | |
| } | |
| data = new Uint8Array([...data, ...chunk]) | |
| }) | |
| res.on('end', () => { | |
| resolve(data) | |
| }) | |
| res.on('error', reject) | |
| }) | |
| }) | |
| export const handler = async (req: Request): Promise<Response> => { | |
| try { | |
| const pathname = _getPathname(req.url) | |
| if (pathname === 'healthcheck') { | |
| return new Response('OK') | |
| } | |
| const imageUrl = _parseUrl(pathname) | |
| if (!imageUrl) { | |
| return new Response(`Invalid URL: ${req.url}`, { status: 400 }) | |
| } | |
| if (!_isDomainAllowed(imageUrl)) { | |
| return new Response(`Domain not allowed: ${req.url}`, { status: 403 }) | |
| } | |
| const imageResponse = await _getImage(imageUrl) | |
| if (!imageResponse || imageResponse.length === 0) { | |
| return new Response(`Fetch failed: ${req.url}`, { status: 400 }) | |
| } | |
| const metadata = await sizeOf(imageResponse) | |
| if (!metadata) { | |
| return new Response(`Invalid image: ${req.url}`, { status: 415 }) | |
| } | |
| return new Response(JSON.stringify(metadata), { | |
| headers: { 'Content-Type': 'application/json' }, | |
| }) | |
| } catch { | |
| return new Response(`Processing failed: ${req.url}`, { status: 500 }) | |
| } | |
| } |
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