feat(scrapeURL): handle PDFs behind anti-bot (#1198)

apps/api/src/__tests__/snips/scrape.test.ts

@@ -150,6 +150,16 @@ describe("Scrape tests", () => {
         });
       }, 15000);
     });
+    
+    describe("PDF (f-e dependant)", () => {
+      it.concurrent("works for PDFs behind anti-bot", async () => {
+        const response = await scrape({
+          url: "https://www.researchgate.net/profile/Amir-Leshem/publication/220732050_Robust_adaptive_beamforming_based_on_jointly_estimating_covariance_matrix_and_steering_vector/links/0c96052d2fd8f0a84b000000/Robust-adaptive-beamforming-based-on-jointly-estimating-covariance-matrix-and-steering-vector.pdf"
+        });
+
+        expect(response.markdown).toContain("Robust adaptive beamforming based on jointly estimating covariance matrix");
+      }, 60000);
+    });
   }
 
   if (!process.env.TEST_SUITE_SELF_HOSTED || process.env.OPENAI_API_KEY) {

apps/api/src/scraper/scrapeURL/engines/fetch/index.ts

@@ -44,7 +44,7 @@ export async function scrapeURLWithFetch(
     }
   }
 
-  specialtyScrapeCheck(
+  await specialtyScrapeCheck(
     meta.logger.child({ method: "scrapeURLWithFetch/specialtyScrapeCheck" }),
     Object.fromEntries(response.headers as any),
   );

apps/api/src/scraper/scrapeURL/engines/fire-engine/index.ts

@@ -133,11 +133,12 @@ async function performFireEngineScrape<
     await new Promise((resolve) => setTimeout(resolve, 250));
   }
 
-  specialtyScrapeCheck(
+  await specialtyScrapeCheck(
     logger.child({
       method: "performFireEngineScrape/specialtyScrapeCheck",
     }),
     status.responseHeaders,
+    status,
   );
 
   const contentType = (Object.entries(status.responseHeaders ?? {}).find(

apps/api/src/scraper/scrapeURL/engines/pdf/index.ts

@@ -7,9 +7,10 @@ import * as Sentry from "@sentry/node";
 import escapeHtml from "escape-html";
 import PdfParse from "pdf-parse";
 import { downloadFile, fetchFileToBuffer } from "../utils/downloadFile";
-import { RemoveFeatureError, UnsupportedFileError } from "../../error";
+import { PDFAntibotError, RemoveFeatureError, UnsupportedFileError } from "../../error";
 import { readFile, unlink } from "node:fs/promises";
 import path from "node:path";
+import type { Response } from "undici";
 
 type PDFProcessorResult = { html: string; markdown?: string };
 
@@ -88,10 +89,20 @@ export async function scrapePDF(
     };
   }
 
-  const { response, tempFilePath } = await downloadFile(meta.id, meta.url, {
+  const { response, tempFilePath } = (meta.pdfPrefetch !== undefined && meta.pdfPrefetch !== null)
+    ? { response: meta.pdfPrefetch, tempFilePath: meta.pdfPrefetch.filePath }
+    : await downloadFile(meta.id, meta.url, {
       headers: meta.options.headers,
     });
   
+  if ((response as any).headers) { // if downloadFile was used
+    const r: Response = response as any;
+    const ct = r.headers.get("Content-Type");
+    if (ct && !ct.includes("application/pdf")) { // if downloaded file wasn't a PDF
+      throw new PDFAntibotError();
+    }
+  }
+
   let result: PDFProcessorResult | null = null;
 
   const base64Content = (await readFile(tempFilePath)).toString("base64");
@@ -142,7 +153,7 @@ export async function scrapePDF(
   await unlink(tempFilePath);
 
   return {
-    url: response.url,
+    url: response.url ?? meta.url,
     statusCode: response.status,
     html: result?.html ?? "",
     markdown: result?.markdown ?? "",

apps/api/src/scraper/scrapeURL/engines/scrapingbee/index.ts

@@ -72,7 +72,7 @@ export function scrapeURLWithScrapingBee(
       });
     }
 
-    specialtyScrapeCheck(
+    await specialtyScrapeCheck(
       meta.logger.child({
         method: "scrapeURLWithScrapingBee/specialtyScrapeCheck",
       }),

apps/api/src/scraper/scrapeURL/engines/utils/specialtyHandler.ts

@@ -1,9 +1,30 @@
 import { Logger } from "winston";
 import { AddFeatureError } from "../../error";
+import { FireEngineCheckStatusSuccess } from "../fire-engine/checkStatus";
+import path from "path";
+import os from "os";
+import { writeFile } from "fs/promises";
+import { Meta } from "../..";
 
-export function specialtyScrapeCheck(
+async function feResToPdfPrefetch(feRes: FireEngineCheckStatusSuccess | undefined): Promise<Meta["pdfPrefetch"]> {
+  if (!feRes?.file) {
+    return null;
+  }
+
+  const filePath = path.join(os.tmpdir(), `tempFile-${crypto.randomUUID()}.pdf`);
+  await writeFile(filePath, Buffer.from(feRes.file.content, "base64"))
+
+  return {
+    status: feRes.pageStatusCode,
+    url: feRes.url,
+    filePath,
+  };
+}
+
+export async function specialtyScrapeCheck(
   logger: Logger,
   headers: Record<string, string> | undefined,
+  feRes?: FireEngineCheckStatusSuccess,
 ) {
   const contentType = (Object.entries(headers ?? {}).find(
     (x) => x[0].toLowerCase() === "content-type",
@@ -18,7 +39,7 @@ export function specialtyScrapeCheck(
     contentType.startsWith("application/pdf;")
   ) {
     // .pdf
-    throw new AddFeatureError(["pdf"]);
+    throw new AddFeatureError(["pdf"], await feResToPdfPrefetch(feRes));
   } else if (
     contentType ===
       "application/vnd.openxmlformats-officedocument.wordprocessingml.document" ||

apps/api/src/scraper/scrapeURL/error.ts

@@ -1,4 +1,4 @@
-import { EngineResultsTracker } from ".";
+import { EngineResultsTracker, Meta } from ".";
 import { Engine, FeatureFlag } from "./engines";
 
 export class EngineError extends Error {
@@ -28,10 +28,12 @@ export class NoEnginesLeftError extends Error {
 
 export class AddFeatureError extends Error {
   public featureFlags: FeatureFlag[];
+  public pdfPrefetch: Meta["pdfPrefetch"];
 
-  constructor(featureFlags: FeatureFlag[]) {
+  constructor(featureFlags: FeatureFlag[], pdfPrefetch?: Meta["pdfPrefetch"]) {
     super("New feature flags have been discovered: " + featureFlags.join(", "));
     this.featureFlags = featureFlags;
+    this.pdfPrefetch = pdfPrefetch;
   }
 }
 
@@ -72,3 +74,9 @@ export class UnsupportedFileError extends Error {
     this.reason = reason;
   }
 }
+
+export class PDFAntibotError extends Error {
+  constructor() {
+    super("PDF scrape was prevented by anti-bot")
+  }
+}

apps/api/src/scraper/scrapeURL/index.ts

@@ -16,6 +16,7 @@ import {
   AddFeatureError,
   EngineError,
   NoEnginesLeftError,
+  PDFAntibotError,
   RemoveFeatureError,
   SiteError,
   TimeoutError,
@@ -49,6 +50,11 @@ export type Meta = {
   logs: any[];
   featureFlags: Set<FeatureFlag>;
   mock: MockState | null;
+  pdfPrefetch: {
+    filePath: string;
+    url?: string;
+    status: number;
+  } | null | undefined; // undefined: no prefetch yet, null: prefetch came back empty
 };
 
 function buildFeatureFlags(
@@ -151,6 +157,7 @@ async function buildMetaObject(
       options.useMock !== undefined
         ? await loadMock(options.useMock, _logger)
         : null,
+    pdfPrefetch: undefined,
   };
 }
 
@@ -309,6 +316,8 @@ async function scrapeURLLoop(meta: Meta): Promise<ScrapeUrlResponse> {
         throw error;
       } else if (error instanceof UnsupportedFileError) {
         throw error;
+      } else if (error instanceof PDFAntibotError) {
+        throw error;
       } else if (error instanceof TimeoutSignal) {
         throw error;
       } else {
@@ -394,6 +403,9 @@ export async function scrapeURL(
           meta.featureFlags = new Set(
             [...meta.featureFlags].concat(error.featureFlags),
           );
+          if (error.pdfPrefetch) {
+            meta.pdfPrefetch = error.pdfPrefetch;
+          }
         } else if (
           error instanceof RemoveFeatureError &&
           meta.internalOptions.forceEngine === undefined
@@ -408,6 +420,21 @@ export async function scrapeURL(
               (x) => !error.featureFlags.includes(x),
             ),
           );
+        } else if (
+          error instanceof PDFAntibotError &&
+          meta.internalOptions.forceEngine === undefined
+        ) {
+          if (meta.pdfPrefetch !== undefined) {
+            meta.logger.error("PDF was prefetched and still blocked by antibot, failing");
+            throw error;
+          } else {
+            meta.logger.debug("PDF was blocked by anti-bot, prefetching with chrome-cdp");
+            meta.featureFlags = new Set(
+              [...meta.featureFlags].filter(
+                (x) => x !== "pdf",
+              ),
+            );
+          }
         } else {
           throw error;
         }