UBERF-9492: Allow restricting hostnames for print service

services/print/pod-print/src/config.ts

@@ -5,14 +5,18 @@
 export interface Config {
   Port: number
   Secret: string
+  AllowedHostnames: string[]
 }
 
 const parseNumber = (str: string | undefined): number | undefined => (str !== undefined ? Number(str) : undefined)
 
 const config: Config = (() => {
+  const allowedHostnames = process.env.ALLOWED_HOSTNAMES
+
   const params: Partial<Config> = {
     Port: parseNumber(process.env.PORT) ?? 4005,
-    Secret: process.env.SECRET
+    Secret: process.env.SECRET,
+    AllowedHostnames: allowedHostnames == null ? [] : allowedHostnames.split(',')
   }
 
   const missingEnv = (Object.keys(params) as Array<keyof Config>).filter((key) => params[key] === undefined)

services/print/pod-print/src/main.ts

@@ -17,7 +17,7 @@ export const main = async (): Promise<void> => {
   setupMetadata()
 
   const storageConfig = storageConfigFromEnv()
-  const { app, close } = createServer(storageConfig)
+  const { app, close } = createServer(storageConfig, config.AllowedHostnames)
   const server = listen(app, config.Port)
 
   const shutdown = (): void => {

services/print/pod-print/src/server.ts

@@ -110,9 +110,13 @@ const wrapRequest = (fn: AsyncRequestHandler) => (req: Request, res: Response, n
   handleRequest(fn, req, res, next)
 }
 
-export function createServer (storageConfig: StorageConfiguration): { app: Express, close: () => void } {
+export function createServer (
+  storageConfig: StorageConfiguration,
+  allowedHostnames: string[]
+): { app: Express, close: () => void } {
   const storageAdapter = buildStorageFromConfig(storageConfig)
   const measureCtx = initStatisticsContext('print', {})
+  const whitelistedHostnames = allowedHostnames.length > 0 ? new Set(allowedHostnames) : null
 
   const app = express()
   app.use(cors())
@@ -124,6 +128,16 @@ export function createServer (storageConfig: StorageConfiguration): { app: Expre
       const rawlink = req.query.link as string
       const link = decodeURIComponent(rawlink)
 
+      // Verify that link is from the same host and protocol is among the allowed
+      const url = new URL(link)
+      if (
+        !['http:', 'https:'].includes(url.protocol) ||
+        (whitelistedHostnames != null && !whitelistedHostnames.has(url.hostname))
+      ) {
+        console.error(`Rejected processing unexpected link: ${link}. Token: ${JSON.stringify(token)}`)
+        throw new ApiError(403, 'Cannot process provided link')
+      }
+
       const kind = req.query.kind as PrintOptions['kind']
 
       if (kind !== undefined && !validKinds.includes(kind as any)) {