Feature/secure print

api/main_endpoints/routes/Printer.js

@@ -7,6 +7,8 @@ const fs = require('fs');
 const path = require('path');
 const { MetricsHandler, register } = require('../../util/metrics.js');
 const { cleanUpChunks, cleanUpExpiredChunks, recordPrintingFolderSize } = require('../util/Printer.js');
+const { PDFDocument, StandardFonts } = require('pdf-lib');
+const {subtractUserPages} = require('../util/userHelpers');
 
 const {
   decodeToken,
@@ -78,7 +80,8 @@ router.post('/sendPrintRequest', upload.single('chunk'), async (req, res) => {
     logger.warn('/sendPrintRequest was requested without a token');
     return res.sendStatus(UNAUTHORIZED);
   }
-  if (!await decodeToken(req)) {
+  const user = await decodeToken(req);
+  if(!user){
     logger.warn('/sendPrintRequest was requested with an invalid token');
     return res.sendStatus(UNAUTHORIZED);
   }
@@ -114,7 +117,18 @@ router.post('/sendPrintRequest', upload.single('chunk'), async (req, res) => {
     }
   }
 
-  const stream = await fs.createReadStream(assembledPdfFromChunks);
+  try{
+    const stream = await fs.promises.readFile(assembledPdfFromChunks); // buffer
+    const pdfDoc = await PDFDocument.load(stream); // load PDF
+    const numpages = pdfDoc.getPages().length; // get number of pages
+    const copiesInt = parseInt(copies || 1, 10);
+    const totalPages = numpages * copiesInt;
+    await subtractUserPages(user.id, totalPages); // updates users printcount
+  }catch(err){
+    logger.error('/sendPrintRequest failed', err); // helper increments totalapges, thrown if exceeded
+    await cleanUpChunks(dir, id);
+    return res.status(400).json({error:err.message});
+  }
   const data = new FormData();
   data.append('file', stream, {filename: id, type: 'application/pdf'});
   data.append('copies', copies);

api/main_endpoints/util/userHelpers.js

@@ -202,6 +202,23 @@ function checkIfPageCountResets(lastLogin) {
 
   return lastLoginWasOverOneWeekAgo || aSundayHasPassedSinceLastLogin;
 }
+// updates users available pages
+async function subtractUserPages(userId, pagesToPrint){
+  const user = await User.findById(userId);
+  if(!user){
+    throw new Error('user not found'); // checks user
+  }
+  if(!Number.isInteger(pagesToPrint) || pagesToPrint <= 0){
+    throw new Error('invalid number');
+  }
+  if (user.pagesPrinted < pagesToPrint) {
+    throw new Error('no pages remaining');
+  }
+
+  user.pagesPrinted -= pagesToPrint;
+  await user.save();
+  return user.pagesPrinted;
+}
 
 module.exports = {
   registerUser,
@@ -211,4 +228,5 @@ module.exports = {
   userWithEmailExists,
   checkIfPageCountResets,
   findPasswordReset,
+  subtractUserPages,
 };