make async database integrity check

backend/src/index.ts

@@ -5,6 +5,7 @@ import path from "path";
 import fs from "fs";
 import { createServer } from "http";
 import { Server } from "socket.io";
+import { Worker } from "worker_threads";
 import multer from "multer";
 import archiver from "archiver";
 import Database from "better-sqlite3";
@@ -125,61 +126,31 @@ const respondWithValidationErrors = (
   });
 };
 
-const validateSqliteHeader = (filePath: string): boolean => {
-  try {
-    const buffer = Buffer.alloc(16);
-    const fd = fs.openSync(filePath, "r");
-    const bytesRead = fs.readSync(fd, buffer, 0, 16, 0);
-    fs.closeSync(fd);
+// Non-blocking CPU check using worker threads
+const verifyDatabaseIntegrityAsync = (filePath: string): Promise<boolean> => {
+  return new Promise((resolve) => {
+    const worker = new Worker(
+      path.resolve(__dirname, "./workers/db-verify.js"),
+      {
+        workerData: { filePath },
+      }
+    );
 
-    if (bytesRead < 16) {
-      console.warn("File too small to be a valid SQLite database");
-      return false;
-    }
-
-    // SQLite format 3 header: "SQLite format 3\0" (16 bytes)
-    // Hex: 53 51 4c 69 74 65 20 66 6f 72 6d 61 74 20 33 00
-    const expectedHeader = Buffer.from([
-      0x53, 0x51, 0x4c, 0x69, 0x74, 0x65, 0x20, 0x66, 0x6f, 0x72, 0x6d, 0x61,
-      0x74, 0x20, 0x33, 0x00,
-    ]);
-
-    const isValid = buffer.equals(expectedHeader);
-    if (!isValid) {
-      console.warn("Invalid SQLite file header detected", {
-        filePath,
-        header: buffer.toString("hex"),
-        expected: expectedHeader.toString("hex"),
-      });
-    }
-
-    return isValid;
-  } catch (error) {
-    console.error("Failed to validate SQLite header:", error);
-    return false;
-  }
-};
-
-const runIntegrityCheck = (filePath: string): boolean => {
-  // First validate the file header to prevent RCE attacks
-  if (!validateSqliteHeader(filePath)) {
-    return false;
-  }
-
-  let dbInstance: Database.Database | undefined;
-  try {
-    dbInstance = new Database(filePath, {
-      readonly: true,
-      fileMustExist: true,
+    worker.on("message", (isValid: boolean) => resolve(isValid));
+    worker.on("error", (err) => {
+      console.error("Worker error:", err);
+      resolve(false);
     });
-    const result = dbInstance.prepare("PRAGMA integrity_check;").get();
-    return result?.integrity_check === "ok";
-  } catch (error) {
-    console.error("Integrity check failed:", error);
-    return false;
-  } finally {
-    dbInstance?.close();
-  }
+    worker.on("exit", (code) => {
+      if (code !== 0) resolve(false);
+    });
+
+    // Kill worker if it takes too long (DoS protection)
+    setTimeout(() => {
+      worker.terminate();
+      resolve(false);
+    }, 10000); // 10 second timeout
+  });
 };
 
 const removeFileIfExists = (filePath?: string) => {
@@ -685,7 +656,7 @@ app.post("/import/sqlite/verify", upload.single("db"), async (req, res) => {
     }
 
     const stagedPath = req.file.path;
-    const isValid = runIntegrityCheck(stagedPath);
+    const isValid = await verifyDatabaseIntegrityAsync(stagedPath);
     removeFileIfExists(stagedPath);
 
     if (!isValid) {
@@ -724,7 +695,7 @@ app.post("/import/sqlite", upload.single("db"), async (req, res) => {
       return res.status(500).json({ error: "Failed to stage uploaded file" });
     }
 
-    const isValid = runIntegrityCheck(stagedPath);
+    const isValid = await verifyDatabaseIntegrityAsync(stagedPath);
     if (!isValid) {
       removeFileIfExists(stagedPath);
       return res

backend/src/workers/db-verify.js

@@ -0,0 +1,18 @@
+const { parentPort, workerData } = require('worker_threads');
+const Database = require('better-sqlite3');
+
+if (!parentPort) throw new Error("Must be run in a worker thread");
+
+try {
+  const { filePath } = workerData;
+  const db = new Database(filePath, { readonly: true, fileMustExist: true });
+  
+  // This is the CPU-heavy operation
+  const result = db.prepare("PRAGMA integrity_check;").get();
+  
+  db.close();
+  parentPort.postMessage(result.integrity_check === "ok");
+} catch (error) {
+  // Any error means invalid or corrupt DB
+  parentPort.postMessage(false);
+}