refactor(server): extract ZIP security checks into reusable safe-zip module

apps/server/src/server/api/routers/crypto.router.ts

@@ -9,18 +9,13 @@ import {
   sha256Hex,
 } from '@furtherverse/crypto'
 import { ORPCError } from '@orpc/server'
-import type { JSZipObject } from 'jszip'
 import JSZip from 'jszip'
 import { z } from 'zod'
+import { extractSafeZipFiles, ZipValidationError } from '@/server/safe-zip'
 import { getUxConfig } from '@/server/ux-config'
 import { db } from '../middlewares'
 import { os } from '../server'
 
-interface ZipFileItem {
-  name: string
-  bytes: Uint8Array
-}
-
 const summaryPayloadSchema = z
   .object({
     taskId: z.string().min(1, 'summary.json must contain a non-empty taskId'),
@@ -29,84 +24,6 @@ const summaryPayloadSchema = z
   })
   .loose()
 
-const MAX_RAW_ZIP_BYTES = 50 * 1024 * 1024
-const MAX_SINGLE_FILE_BYTES = 20 * 1024 * 1024
-const MAX_TOTAL_UNCOMPRESSED_BYTES = 60 * 1024 * 1024
-const MAX_ZIP_ENTRIES = 64
-
-const normalizePath = (name: string): string => name.replaceAll('\\', '/')
-
-const isUnsafePath = (name: string): boolean => {
-  const normalized = normalizePath(name)
-  const segments = normalized.split('/')
-
-  return (
-    normalized.startsWith('/') ||
-    normalized.includes('\u0000') ||
-    segments.some((segment) => segment === '..' || segment.trim().length === 0)
-  )
-}
-
-const listSafeZipFiles = async (rawZip: JSZip): Promise<ZipFileItem[]> => {
-  const entries = Object.values(rawZip.files) as JSZipObject[]
-  if (entries.length > MAX_ZIP_ENTRIES) {
-    throw new ORPCError('BAD_REQUEST', {
-      message: `Zip contains too many entries: ${entries.length}`,
-    })
-  }
-
-  let totalUncompressedBytes = 0
-  const files: ZipFileItem[] = []
-  const seen = new Set<string>()
-
-  for (const entry of entries) {
-    if (entry.dir) {
-      continue
-    }
-
-    if (isUnsafePath(entry.name)) {
-      throw new ORPCError('BAD_REQUEST', {
-        message: `Zip contains unsafe entry path: ${entry.name}`,
-      })
-    }
-
-    const normalizedName = normalizePath(entry.name)
-    if (seen.has(normalizedName)) {
-      throw new ORPCError('BAD_REQUEST', {
-        message: `Zip contains duplicate entry: ${normalizedName}`,
-      })
-    }
-    seen.add(normalizedName)
-
-    const content = await entry.async('uint8array')
-    if (content.byteLength > MAX_SINGLE_FILE_BYTES) {
-      throw new ORPCError('BAD_REQUEST', {
-        message: `Zip entry too large: ${normalizedName}`,
-      })
-    }
-
-    totalUncompressedBytes += content.byteLength
-    if (totalUncompressedBytes > MAX_TOTAL_UNCOMPRESSED_BYTES) {
-      throw new ORPCError('BAD_REQUEST', {
-        message: 'Zip total uncompressed content exceeds max size limit',
-      })
-    }
-
-    files.push({
-      name: normalizedName,
-      bytes: content,
-    })
-  }
-
-  if (files.length === 0) {
-    throw new ORPCError('BAD_REQUEST', {
-      message: 'Zip has no file entries',
-    })
-  }
-
-  return files
-}
-
 const requireIdentity = async (dbInstance: Parameters<typeof getUxConfig>[0]) => {
   const config = await getUxConfig(dbInstance)
   if (!config || !config.licence) {
@@ -155,25 +72,15 @@ export const signAndPackReport = os.crypto.signAndPackReport.use(db).handler(asy
     })
   }
 
-  const rawZipArrayBuffer = await input.rawZip.arrayBuffer()
-  const rawZipBytes = Buffer.from(rawZipArrayBuffer)
+  const rawZipBytes = Buffer.from(await input.rawZip.arrayBuffer())
 
-  if (rawZipBytes.byteLength === 0 || rawZipBytes.byteLength > MAX_RAW_ZIP_BYTES) {
-    throw new ORPCError('BAD_REQUEST', {
-      message: 'rawZip is empty or exceeds max size limit',
-    })
-  }
-
-  const rawZip = await JSZip.loadAsync(rawZipBytes, {
-    checkCRC32: true,
-  }).catch(() => {
-    throw new ORPCError('BAD_REQUEST', {
-      message: 'rawZip is not a valid zip file',
-    })
+  const zipFiles = await extractSafeZipFiles(rawZipBytes).catch((error) => {
+    if (error instanceof ZipValidationError) {
+      throw new ORPCError('BAD_REQUEST', { message: error.message })
+    }
+    throw error
   })
 
-  const zipFiles = await listSafeZipFiles(rawZip)
-
   // Extract and validate summary.json from the ZIP
   const summaryFile = zipFiles.find((f) => f.name === 'summary.json')
   if (!summaryFile) {

apps/server/src/server/safe-zip.ts

@@ -0,0 +1,96 @@
+import type { JSZipObject } from 'jszip'
+import JSZip from 'jszip'
+
+export class ZipValidationError extends Error {
+  override name = 'ZipValidationError'
+}
+
+export interface ZipFileItem {
+  name: string
+  bytes: Uint8Array
+}
+
+export interface SafeZipOptions {
+  maxRawBytes?: number
+  maxEntries?: number
+  maxSingleFileBytes?: number
+  maxTotalUncompressedBytes?: number
+}
+
+const DEFAULTS = {
+  maxRawBytes: 50 * 1024 * 1024,
+  maxEntries: 64,
+  maxSingleFileBytes: 20 * 1024 * 1024,
+  maxTotalUncompressedBytes: 60 * 1024 * 1024,
+} satisfies Required<SafeZipOptions>
+
+const normalizePath = (name: string): string => name.replaceAll('\\', '/')
+
+const isUnsafePath = (name: string): boolean => {
+  const normalized = normalizePath(name)
+  const segments = normalized.split('/')
+
+  return (
+    normalized.startsWith('/') ||
+    normalized.includes('\0') ||
+    segments.some((segment) => segment === '..' || segment.trim().length === 0)
+  )
+}
+
+export const extractSafeZipFiles = async (
+  rawBytes: Uint8Array | Buffer,
+  options?: SafeZipOptions,
+): Promise<ZipFileItem[]> => {
+  const opts = { ...DEFAULTS, ...options }
+
+  if (rawBytes.byteLength === 0 || rawBytes.byteLength > opts.maxRawBytes) {
+    throw new ZipValidationError('ZIP is empty or exceeds max size limit')
+  }
+
+  const zip = await JSZip.loadAsync(rawBytes, { checkCRC32: true }).catch(() => {
+    throw new ZipValidationError('Not a valid ZIP file')
+  })
+
+  const entries = Object.values(zip.files) as JSZipObject[]
+  if (entries.length > opts.maxEntries) {
+    throw new ZipValidationError(`ZIP contains too many entries: ${entries.length}`)
+  }
+
+  let totalUncompressedBytes = 0
+  const files: ZipFileItem[] = []
+  const seen = new Set<string>()
+
+  for (const entry of entries) {
+    if (entry.dir) {
+      continue
+    }
+
+    if (isUnsafePath(entry.name)) {
+      throw new ZipValidationError(`ZIP contains unsafe entry path: ${entry.name}`)
+    }
+
+    const normalizedName = normalizePath(entry.name)
+    if (seen.has(normalizedName)) {
+      throw new ZipValidationError(`ZIP contains duplicate entry: ${normalizedName}`)
+    }
+    seen.add(normalizedName)
+
+    const content = await entry.async('uint8array')
+    if (content.byteLength > opts.maxSingleFileBytes) {
+      throw new ZipValidationError(`ZIP entry too large: ${normalizedName}`)
+    }
+
+    totalUncompressedBytes += content.byteLength
+    if (totalUncompressedBytes > opts.maxTotalUncompressedBytes) {
+      throw new ZipValidationError('ZIP total uncompressed content exceeds max size limit')
+    }
+
+    files.push({ name: normalizedName, bytes: content })
+  }
+
+  if (files.length === 0) {
+    throw new ZipValidationError('ZIP has no file entries')
+  }
+
+  return files
+}