/api/proxy cancels downloading large files and long operations

.env.example

@@ -13,6 +13,8 @@ POSTGRESQL_DB=framna-docs
 REPOSITORY_NAME_SUFFIX=-openapi
 HIDDEN_REPOSITORIES=
 NEW_PROJECT_TEMPLATE_REPOSITORY=shapehq/starter-openapi
+PROXY_API_MAXIMUM_FILE_SIZE_IN_MEGABYTES = 10
+PROXY_API_TIMEOUT_IN_SECONDS = 30
 GITHUB_WEBHOOK_SECRET=preshared secret also put in app configuration in GitHub
 GITHUB_WEBHOK_REPOSITORY_ALLOWLIST=
 GITHUB_WEBHOK_REPOSITORY_DISALLOWLIST=

src/app/api/proxy/route.ts

@@ -1,7 +1,12 @@
 import { NextRequest, NextResponse } from "next/server"
-import { makeAPIErrorResponse, makeUnauthenticatedAPIErrorResponse } from "@/common"
+import { env, makeAPIErrorResponse, makeUnauthenticatedAPIErrorResponse } from "@/common"
 import { session } from "@/composition"
 
+const ErrorName = {
+  MAX_FILE_SIZE_EXCEEDED: "MaxFileSizeExceededError",
+  TIMEOUT: "TimeoutError"
+}
+
 export async function GET(req: NextRequest) {
   const isAuthenticated = await session.getIsAuthenticated()
   if (!isAuthenticated) {
@@ -17,6 +22,63 @@ export async function GET(req: NextRequest) {
   } catch {
     return makeAPIErrorResponse(400, "Invalid \"url\" query parameter.")
   }
-  const file = await fetch(url).then(r => r.blob())
-  return new NextResponse(file, { status: 200 })
+  try {
+    const maxMegabytes = Number(env.getOrThrow("PROXY_API_MAXIMUM_FILE_SIZE_IN_MEGABYTES"))
+    const timeoutInSeconds = Number(env.getOrThrow("PROXY_API_TIMEOUT_IN_SECONDS"))
+    const maxBytes = maxMegabytes * 1024 * 1024
+    const file = await downloadFile({ url, maxBytes, timeoutInSeconds })
+    return new NextResponse(file, { status: 200 })
+  } catch (error) {
+    if (error instanceof Error == false) {
+      return makeAPIErrorResponse(500, "An unknown error occurred.")
+    }
+    if (error.name === ErrorName.MAX_FILE_SIZE_EXCEEDED) {
+      return makeAPIErrorResponse(413, "The operation was aborted.")
+    } else if (error.name === ErrorName.TIMEOUT) {
+      return makeAPIErrorResponse(408, "The operation timed out.")
+    } else {
+      return makeAPIErrorResponse(500, error.message)
+    }
+  }
+}
+
+async function downloadFile(params: {
+  url: URL,
+  maxBytes: number,
+  timeoutInSeconds: number
+}): Promise<Blob> {
+  const { url, maxBytes, timeoutInSeconds } = params
+  const abortController = new AbortController()
+  const timeoutSignal = AbortSignal.timeout(timeoutInSeconds * 1000)
+  const response = await fetch(url, {
+    signal: AbortSignal.any([abortController.signal, timeoutSignal])
+  })
+  if (!response.body) {
+    throw new Error("Response body unavailable")
+  }
+  let totalBytes = 0
+  let didExceedMaxBytes = false
+  const reader = response.body.getReader()
+  const chunks: Uint8Array[] = []
+  // eslint-disable-next-line no-constant-condition
+  while (true) {
+    // eslint-disable-next-line no-await-in-loop
+    const { done, value } = await reader.read()
+    if (done) {
+      break
+    }
+    totalBytes += value.length
+    chunks.push(value)
+    if (totalBytes >= maxBytes) {
+      didExceedMaxBytes = true
+      abortController.abort()
+      break
+    }
+  }
+  if (didExceedMaxBytes) {
+    const error = new Error("Maximum file size exceeded")
+    error.name = ErrorName.MAX_FILE_SIZE_EXCEEDED
+    throw error
+  }
+  return new Blob(chunks)
 }