fix: throw error if there is unsported signature in the pdf

.gitignore

@@ -2,3 +2,4 @@ node_modules
 .idea
 yarn-error.log
 __tests__/outputs/**
+.DS_Store

__tests__/index.test.ts

@@ -2,7 +2,7 @@ import * as fs from "fs";
 import * as path from "path";
 import { describe, it, expect } from "@jest/globals";
 import PDFparser from "../src/pdfParser";
-import { AppError } from "../src/lib/errors";
+import { AppError, GeneralError } from "../src/lib/errors";
 
 describe("PDF parser", () => {
   it("should return pdf document metadata including signatures", async () => {
@@ -49,4 +49,17 @@ describe("PDF parser", () => {
       expect(error.message).toEqual("Only pdf file type is supported");
     }
   });
+
+  it("should throw error when parsing file with unsupported subfilter type", async () => {
+    const file = fs.readFileSync(
+      path.resolve(__dirname, "./source/sample07.pdf")
+    );
+
+    try {
+      const parser = new PDFparser(file);
+      await parser.getPDFMeta();
+    } catch (error) {
+      expect(error).toBeInstanceOf(GeneralError);
+    }
+  });
 });

src/lib/generalUtils.ts

@@ -5,6 +5,7 @@ const DEFAULT_BYTE_RANGE_PLACEHOLDER = "**********";
 export const checkForSubFilter = (pdfBuffer: Buffer) => {
   const matches = pdfBuffer.toString().match(/\/SubFilter\s*\/([\w.]*)/);
   const subFilter = Array.isArray(matches) && matches[1];
+
   if (!subFilter) {
     throw new AppError("Can not find subfilter");
   }
@@ -16,7 +17,9 @@ export const checkForSubFilter = (pdfBuffer: Buffer) => {
   ];
 
   if (!supportedTypes.includes(subFilter.trim().toLowerCase())) {
-    throw new AppError("Subfilter not supported");
+    throw new AppError(
+      `Subfilter not supported - ${subFilter.trim().toLowerCase()}`
+    );
   }
 };
 

src/lib/index.ts

@@ -7,8 +7,7 @@ export const verifyPDF = (pdf: Buffer) => {
   try {
     checkForSubFilter(pdfBuffer);
   } catch (error) {
-    console.log("no supported signatures found");
-    return null;
+    throw new Error(error.message);
   }
 
   try {