서버, 클라이언트, 서비스 워커 공용 코드를 lib/shared로 분리하고 브라우저 전용 모듈을 lib/client로 재구성

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/hooks.client.ts

@@ -1,12 +1,12 @@
 import type { ClientInit } from "@sveltejs/kit/hooks";
+import { prepareFileCache } from "#lib/client/cache/index.js";
+import { listenForMetadataRequests } from "#lib/client/serviceWorker.js";
 import {
   cleanupDanglingInfos,
   getClientKey,
   getMasterKeys,
   getHmacSecrets,
-} from "#lib/indexedDB/index.js";
+} from "#lib/client/storage/indexedDB/index.js";
-import { prepareFileCache } from "#lib/modules/file/index.js";
-import { listenForMetadataRequests } from "#lib/serviceWorker/index.js";
 import { clientKeyStore, masterKeyStore, hmacSecretStore } from "#lib/stores/index.js";
 
 const requestPersistentStorage = async () => {

src/lib/client/cache/fileCache.ts

@@ -3,8 +3,8 @@ import {
   storeFileCacheIndex,
   deleteFileCacheIndex,
   type FileCacheIndex,
-} from "#lib/indexedDB/index.js";
+} from "#lib/client/storage/indexedDB/index.js";
-import { readFile, writeFile, deleteFile } from "#lib/modules/opfs.js";
+import { readFile, writeFile, deleteFile } from "#lib/client/storage/opfs.js";
 
 const fileCacheIndex = new Map<number, FileCacheIndex>();
 

src/lib/client/cache/index.ts

@@ -0,0 +1,2 @@
+export * from "./fileCache";
+export * from "./thumbnailCache";

src/lib/client/cache/thumbnailCache.ts

@@ -1,9 +1,9 @@
 import { LRUCache } from "lru-cache";
 import { writable, type Writable } from "svelte/store";
-import { decryptChunk } from "#lib/modules/crypto/index.js";
+import { getThumbnailUrl } from "#lib/client/media/thumbnail.js";
+import { readFile, writeFile, deleteFile, deleteDirectory } from "#lib/client/storage/opfs.js";
 import type { SummarizedFileInfo } from "#lib/modules/filesystem/index.js";
-import { readFile, writeFile, deleteFile, deleteDirectory } from "#lib/modules/opfs.js";
+import { decryptChunk } from "#lib/shared/crypto/index.js";
-import { getThumbnailUrl } from "#lib/modules/thumbnail.js";
 
 const loadedThumbnails = new LRUCache<number, Writable<string>>({ max: 100 });
 const loadingThumbnails = new Map<number, Writable<string | undefined>>();

src/lib/client/crypto/hmac.ts

@@ -1,23 +1,7 @@
-import HmacWorker from "#workers/hmac.js?worker";
 import type { ComputeMessage, ResultMessage } from "#workers/hmac.js";
+import HmacWorker from "#workers/hmac.js?worker";
 
-export const digestMessage = async (message: BufferSource) => {
+// Computes HMAC of large blobs incrementally in a worker, which WebCrypto doesn't support
-  return await crypto.subtle.digest("SHA-256", message);
-};
-
-export const generateHmacSecret = async () => {
-  return {
-    hmacSecret: await crypto.subtle.generateKey(
-      {
-        name: "HMAC",
-        hash: "SHA-256",
-      } satisfies HmacKeyGenParams,
-      true,
-      ["sign", "verify"],
-    ),
-  };
-};
-
 export const signMessageHmac = async (message: Blob, hmacSecret: CryptoKey) => {
   const stream = message.stream();
   const hmacSecretRaw = new Uint8Array(await crypto.subtle.exportKey("raw", hmacSecret));

src/lib/client/media/exif.ts

@@ -0,0 +1,27 @@
+import ExifReader from "exifreader";
+
+export const extractExifDateTime = (fileBuffer: ArrayBuffer) => {
+  const exif = ExifReader.load(fileBuffer);
+  const dateTimeOriginal = exif["DateTimeOriginal"]?.description;
+  const offsetTimeOriginal = exif["OffsetTimeOriginal"]?.description;
+  if (!dateTimeOriginal) return undefined;
+
+  const [date, time] = dateTimeOriginal.split(" ");
+  if (!date || !time) return undefined;
+
+  const [year, month, day] = date.split(":").map(Number);
+  const [hour, minute, second] = time.split(":").map(Number);
+  if (!year || !month || !day || !hour || !minute || !second) return undefined;
+
+  if (!offsetTimeOriginal) {
+    // No timezone information.. Assume local timezone
+    return new Date(year, month - 1, day, hour, minute, second);
+  }
+
+  const offsetSign = offsetTimeOriginal[0] === "+" ? 1 : -1;
+  const [offsetHour, offsetMinute] = offsetTimeOriginal.slice(1).split(":").map(Number);
+
+  const utcDate = Date.UTC(year, month - 1, day, hour, minute, second);
+  const offsetMs = offsetSign * ((offsetHour ?? 0) * 60 + (offsetMinute ?? 0)) * 60 * 1000;
+  return new Date(utcDate - offsetMs);
+};

src/lib/client/media/thumbnail.ts

@@ -1,4 +1,4 @@
-import { encodeToBase64 } from "#lib/modules/crypto/index.js";
+import { encodeToBase64 } from "#lib/shared/crypto/index.js";
 
 const scaleSize = (width: number, height: number, targetSize: number) => {
   if (width <= targetSize || height <= targetSize) {

src/lib/client/serviceWorker.ts

@@ -1,5 +1,9 @@
-import { DECRYPTED_FILE_URL_PREFIX } from "#lib/constants/index.js";
+import { DECRYPTED_FILE_URL_PREFIX } from "#lib/shared/serviceWorker.js";
-import type { FileMetadata, ServiceWorkerMessage, ServiceWorkerResponse } from "./types";
+import type {
+  FileMetadata,
+  ServiceWorkerMessage,
+  ServiceWorkerResponse,
+} from "#lib/shared/serviceWorker.js";
 
 const PREPARE_TIMEOUT_MS = 5000;
 

src/lib/client/transfer/chunkedUpload.ts

@@ -1,9 +1,9 @@
 import { sha256 } from "@noble/hashes/sha2.js";
 import axios from "axios";
 import pLimit from "p-limit";
-import { ENCRYPTION_OVERHEAD, CHUNK_SIZE } from "#lib/constants/index.js";
+import { encodeToBase64, encryptChunk } from "#lib/shared/crypto/index.js";
-import { encodeToBase64, encryptChunk } from "#lib/modules/crypto/index.js";
+import { CHUNK_SIZE, getChunkCount, getEncryptedSize } from "#lib/shared/format/index.js";
-import { BoundedQueue } from "#lib/utils/index.js";
+import { BoundedQueue } from "#lib/utils/concurrency/index.js";
 
 interface UploadStats {
   progress: number;
@@ -98,8 +98,8 @@ export const uploadBlob = async (
   const networkConcurrency = options?.concurrency ?? 4;
   const maxQueueSize = 8;
 
-  const totalChunks = Math.ceil(blob.size / CHUNK_SIZE);
+  const totalChunks = getChunkCount(blob.size);
-  const totalBytes = blob.size + totalChunks * ENCRYPTION_OVERHEAD;
+  const totalBytes = getEncryptedSize(blob.size);
 
   const uploadedByChunk = new Array<number>(totalChunks).fill(0);
   const speedMeter = createSpeedMeter(3000, 200);

src/lib/client/transfer/download.svelte.ts

@@ -1,7 +1,7 @@
 import axios from "axios";
 import { limitFunction } from "p-limit";
-import { ENCRYPTED_CHUNK_SIZE } from "#lib/constants/index.js";
+import { decryptChunk, concatenateBuffers } from "#lib/shared/crypto/index.js";
-import { decryptChunk, concatenateBuffers } from "#lib/modules/crypto/index.js";
+import { ENCRYPTED_CHUNK_SIZE } from "#lib/shared/format/index.js";
 
 export interface FileDownloadState {
   id: number;

src/lib/client/transfer/index.ts

@@ -1,4 +1,2 @@
-export * from "./cache";
 export * from "./download.svelte";
-export * from "./thumbnail";
 export * from "./upload.svelte";

src/lib/client/transfer/upload.svelte.ts

@@ -1,15 +1,15 @@
-import ExifReader from "exifreader";
 import { limitFunction } from "p-limit";
-import { CHUNK_SIZE } from "#lib/constants/index.js";
+import { signMessageHmac } from "#lib/client/crypto/hmac.js";
+import { extractExifDateTime } from "#lib/client/media/exif.js";
+import { generateThumbnail } from "#lib/client/media/thumbnail.js";
+import { uploadBlob } from "#lib/client/transfer/chunkedUpload.js";
 import {
   encodeToBase64,
   generateDataKey,
   wrapDataKey,
   encryptString,
-} from "#lib/modules/crypto/index.js";
+} from "#lib/shared/crypto/index.js";
-import { signMessageHmac } from "#lib/modules/crypto/index.js";
+import { getChunkCount } from "#lib/shared/format/index.js";
-import { generateThumbnail } from "#lib/modules/thumbnail.js";
-import { uploadBlob } from "#lib/modules/upload.js";
 import type { MasterKey, HmacSecret } from "#lib/stores/index.js";
 import { Scheduler } from "#lib/utils/index.js";
 import { trpc } from "#trpc/client.js";
@@ -84,32 +84,6 @@ const getFileType = (file: File) => {
   throw new Error("Unknown file type");
 };
 
-const extractExifDateTime = (fileBuffer: ArrayBuffer) => {
-  const exif = ExifReader.load(fileBuffer);
-  const dateTimeOriginal = exif["DateTimeOriginal"]?.description;
-  const offsetTimeOriginal = exif["OffsetTimeOriginal"]?.description;
-  if (!dateTimeOriginal) return undefined;
-
-  const [date, time] = dateTimeOriginal.split(" ");
-  if (!date || !time) return undefined;
-
-  const [year, month, day] = date.split(":").map(Number);
-  const [hour, minute, second] = time.split(":").map(Number);
-  if (!year || !month || !day || !hour || !minute || !second) return undefined;
-
-  if (!offsetTimeOriginal) {
-    // No timezone information.. Assume local timezone
-    return new Date(year, month - 1, day, hour, minute, second);
-  }
-
-  const offsetSign = offsetTimeOriginal[0] === "+" ? 1 : -1;
-  const [offsetHour, offsetMinute] = offsetTimeOriginal.slice(1).split(":").map(Number);
-
-  const utcDate = Date.UTC(year, month - 1, day, hour, minute, second);
-  const offsetMs = offsetSign * ((offsetHour ?? 0) * 60 + (offsetMinute ?? 0)) * 60 * 1000;
-  return new Date(utcDate - offsetMs);
-};
-
 interface FileMetadata {
   parentId: "root" | number;
   name: string;
@@ -140,7 +114,7 @@ const requestFileMetadataEncryption = limitFunction(
       ]);
 
     const { uploadId } = await trpc.upload.startFileUpload.mutate({
-      chunks: Math.ceil(file.size / CHUNK_SIZE),
+      chunks: getChunkCount(file.size),
       parent: fileMetadata.parentId,
       mekVersion: masterKey.version,
       dek: dataKeyWrapped,

src/lib/components/atoms/buttons/FileThumbnailButton.svelte

@@ -1,5 +1,5 @@
 <script lang="ts">
-  import { getFileThumbnail } from "#lib/modules/file/index.js";
+  import { getFileThumbnail } from "#lib/client/cache/index.js";
   import type { SummarizedFileInfo } from "#lib/modules/filesystem/index.js";
 
   import IconFavorite from "~icons/material-symbols/favorite";

src/lib/constants/index.ts

@@ -1,2 +0,0 @@
-export * from "./serviceWorker";
-export * from "./upload";

src/lib/constants/serviceWorker.ts

@@ -1 +0,0 @@
-export const DECRYPTED_FILE_URL_PREFIX = "/_internal/decryptedFile/";

src/lib/constants/upload.ts

@@ -1,6 +0,0 @@
-export const AES_GCM_IV_SIZE = 12;
-export const AES_GCM_TAG_SIZE = 16;
-export const ENCRYPTION_OVERHEAD = AES_GCM_IV_SIZE + AES_GCM_TAG_SIZE;
-
-export const CHUNK_SIZE = 4 * 1024 * 1024; // 4 MiB
-export const ENCRYPTED_CHUNK_SIZE = CHUNK_SIZE + ENCRYPTION_OVERHEAD;

src/lib/modules/filesystem/category.ts

@@ -1,4 +1,4 @@
-import * as IndexedDB from "#lib/indexedDB/index.js";
+import * as IndexedDB from "#lib/client/storage/indexedDB/index.js";
 import { trpc, isTRPCClientError } from "#trpc/client.js";
 import { FilesystemCache, decryptFileMetadata, decryptCategoryMetadata } from "./internal.svelte";
 import type { CategoryInfo, MaybeCategoryInfo } from "./types";

src/lib/modules/filesystem/directory.ts

@@ -1,4 +1,4 @@
-import * as IndexedDB from "#lib/indexedDB/index.js";
+import * as IndexedDB from "#lib/client/storage/indexedDB/index.js";
 import { trpc, isTRPCClientError } from "#trpc/client.js";
 import { FilesystemCache, decryptDirectoryMetadata, decryptFileMetadata } from "./internal.svelte";
 import type { DirectoryInfo, MaybeDirectoryInfo } from "./types";

src/lib/modules/filesystem/file.ts

@@ -1,4 +1,4 @@
-import * as IndexedDB from "#lib/indexedDB/index.js";
+import * as IndexedDB from "#lib/client/storage/indexedDB/index.js";
 import { trpc, isTRPCClientError } from "#trpc/client.js";
 import { FilesystemCache, decryptFileMetadata, decryptCategoryMetadata } from "./internal.svelte";
 import type { FileInfo, MaybeFileInfo } from "./types";

src/lib/modules/filesystem/internal.svelte.ts

@@ -1,5 +1,5 @@
 import { untrack } from "svelte";
-import { unwrapDataKey, decryptString } from "#lib/modules/crypto/index.js";
+import { unwrapDataKey, decryptString } from "#lib/shared/crypto/index.js";
 
 interface FilesystemCacheOptions<K, V> {
   fetchFromIndexedDB: (key: K) => Promise<V | undefined>;

src/lib/modules/http.ts

@@ -1,14 +0,0 @@
-export const parseRangeHeader = (value: string | null) => {
-  if (!value) return undefined;
-
-  const firstRange = value.split(",")[0]!.trim();
-  const parts = firstRange.replace(/bytes=/, "").split("-");
-  return {
-    start: parts[0] ? parseInt(parts[0], 10) : undefined,
-    end: parts[1] ? parseInt(parts[1], 10) : undefined,
-  };
-};
-
-export const getContentRangeHeader = (range?: { start: number; end: number; total: number }) => {
-  return range && { "Content-Range": `bytes ${range.start}-${range.end}/${range.total}` };
-};

src/lib/modules/key.ts

@@ -1,5 +1,5 @@
 import { z } from "zod";
-import { storeClientKey } from "#lib/indexedDB/index.js";
+import { storeClientKey } from "#lib/client/storage/indexedDB/index.js";
 import type { ClientKeys } from "#lib/stores/index.js";
 
 const SerializedClientKeysSchema = z.intersection(

src/lib/server/services/file.ts

@@ -2,10 +2,9 @@ import { FileRepo, MediaRepo } from "#lib/server/db/index.js";
 import type { Ciphertext } from "#lib/server/db/schema/index.js";
 import { AppError } from "#lib/server/errors.js";
 import { createEncContentStream } from "#lib/server/storage/index.js";
+import type { RangeRequest } from "#lib/shared/http.js";
 import { schedulePendingFileDeletions } from "./fileDeletion";
 
-type Range = { start?: number; end?: number };
-
 export const getFile = async (userId: number, fileId: number) => {
   const file = await FileRepo.getFile(userId, fileId);
   if (!file) {
@@ -68,7 +67,7 @@ export const getFileThumbnail = async (userId: number, fileId: number) => {
 
 const decodeIv = (iv: string | null) => (iv ? Buffer.from(iv, "base64") : undefined);
 
-export const getFileStream = async (userId: number, fileId: number, range?: Range) => {
+export const getFileStream = async (userId: number, fileId: number, range?: RangeRequest) => {
   const file = await FileRepo.getFile(userId, fileId);
   if (!file) {
     throw new AppError("NOT_FOUND", "File not found");
@@ -76,7 +75,11 @@ export const getFileStream = async (userId: number, fileId: number, range?: Rang
   return await createEncContentStream(file.path, decodeIv(file.encContentIv), range);
 };
 
-export const getFileThumbnailStream = async (userId: number, fileId: number, range?: Range) => {
+export const getFileThumbnailStream = async (
+  userId: number,
+  fileId: number,
+  range?: RangeRequest,
+) => {
   const thumbnail = await getFileThumbnail(userId, fileId);
   return await createEncContentStream(thumbnail.path, decodeIv(thumbnail.encContentIv), range);
 };

src/lib/server/storage/chunks.ts

@@ -1,7 +1,7 @@
 import { open } from "fs/promises";
 import type { Readable } from "stream";
-import { ENCRYPTION_OVERHEAD, ENCRYPTED_CHUNK_SIZE } from "#lib/constants/index.js";
 import { AppError } from "#lib/server/errors.js";
+import { ENCRYPTION_OVERHEAD, ENCRYPTED_CHUNK_SIZE } from "#lib/shared/format/index.js";
 
 const invalidChunkSize = () => new AppError("BAD_REQUEST", "Invalid chunk size");
 

src/lib/server/storage/streams.ts

@@ -2,22 +2,22 @@ import { createReadStream } from "fs";
 import { stat } from "fs/promises";
 import { Readable } from "stream";
 import { AppError } from "#lib/server/errors.js";
+import { resolveRange, type RangeRequest } from "#lib/shared/http.js";
 
 export const createEncContentStream = async (
   path: string,
   iv?: Buffer,
-  range?: { start?: number; end?: number },
+  rangeRequest?: RangeRequest,
 ) => {
   const { size: fileSize } = await stat(path);
   const ivSize = iv?.byteLength ?? 0;
-  const totalSize = fileSize + ivSize;
 
-  const start = range?.start ?? 0;
+  const range = resolveRange(rangeRequest, fileSize + ivSize);
-  const end = range?.end ?? totalSize - 1;
+  if (!range) {
-  if (start > end || start < 0 || end >= totalSize) {
     throw new AppError("RANGE_NOT_SATISFIABLE", "Invalid range");
   }
 
+  const { start, end } = range;
   return {
     encContentStream: Readable.toWeb(
       Readable.from(
@@ -34,7 +34,7 @@ export const createEncContentStream = async (
         })(),
       ),
     ),
-    range: { start, end, total: totalSize },
+    range,
-    isRangeRequest: !!range,
+    isRangeRequest: !!rangeRequest,
   };
 };

src/lib/serviceWorker/index.ts

@@ -1,2 +0,0 @@
-export * from "./client";
-export * from "./types";

src/lib/services/auth.ts

@@ -1,4 +1,4 @@
-import { encodeToBase64, decryptChallenge, signMessageRSA } from "#lib/modules/crypto/index.js";
+import { encodeToBase64, decryptChallenge, signMessageRSA } from "#lib/shared/crypto/index.js";
 import { trpc, isTRPCClientError } from "#trpc/client.js";
 
 export const requestSessionUpgrade = async (

src/lib/services/category.ts

@@ -1,4 +1,4 @@
-import { generateDataKey, wrapDataKey, encryptString } from "#lib/modules/crypto/index.js";
+import { generateDataKey, wrapDataKey, encryptString } from "#lib/shared/crypto/index.js";
 import type { MasterKey } from "#lib/stores/index.js";
 import { trpc } from "#trpc/client.js";
 

src/lib/services/file.ts

@@ -1,12 +1,12 @@
-import { getAllFileInfos } from "#lib/indexedDB/filesystem.js";
 import {
   getFileCache,
   storeFileCache,
   deleteFileCache,
-  downloadFile,
   deleteFileThumbnailCache,
-} from "#lib/modules/file/index.js";
+} from "#lib/client/cache/index.js";
-import { uploadBlob } from "#lib/modules/upload.js";
+import { getAllFileInfos } from "#lib/client/storage/indexedDB/filesystem.js";
+import { uploadBlob } from "#lib/client/transfer/chunkedUpload.js";
+import { downloadFile } from "#lib/client/transfer/index.js";
 import { trpc } from "#trpc/client.js";
 
 export const requestFileDownload = async (

src/lib/services/key.ts

@@ -1,4 +1,5 @@
-import { storeMasterKeys } from "#lib/indexedDB/index.js";
+import { storeMasterKeys } from "#lib/client/storage/indexedDB/index.js";
+import { requestSessionUpgrade } from "#lib/services/auth.js";
 import {
   encodeToBase64,
   exportRSAKeyToBase64,
@@ -7,8 +8,7 @@ import {
   unwrapMasterKey,
   signMasterKeyWrapped,
   verifyMasterKeyWrapped,
-} from "#lib/modules/crypto/index.js";
+} from "#lib/shared/crypto/index.js";
-import { requestSessionUpgrade } from "#lib/services/auth.js";
 import { masterKeyStore, type ClientKeys } from "#lib/stores/index.js";
 import { trpc, isTRPCClientError } from "#trpc/client.js";
 

src/lib/shared/crypto/aes.ts

@@ -1,11 +1,11 @@
-import { AES_GCM_IV_SIZE } from "#lib/constants/index.js";
+import { AES_GCM_IV_SIZE } from "#lib/shared/format/index.js";
 import {
   encodeString,
   decodeString,
   encodeToBase64,
   decodeFromBase64,
   concatenateBuffers,
-} from "./utils";
+} from "./encoding";
 
 export const generateMasterKey = async () => {
   return {

src/lib/shared/crypto/index.ts

@@ -1,4 +1,4 @@
 export * from "./aes";
+export * from "./encoding";
 export * from "./rsa";
 export * from "./sha";
-export * from "./utils";

src/lib/shared/crypto/rsa.ts

@@ -1,4 +1,4 @@
-import { encodeString, encodeToBase64, decodeFromBase64 } from "./utils";
+import { encodeString, encodeToBase64, decodeFromBase64 } from "./encoding";
 
 export const generateEncryptionKeyPair = async () => {
   const keyPair = await crypto.subtle.generateKey(

src/lib/shared/crypto/sha.ts

@@ -0,0 +1,16 @@
+export const digestMessage = async (message: BufferSource) => {
+  return await crypto.subtle.digest("SHA-256", message);
+};
+
+export const generateHmacSecret = async () => {
+  return {
+    hmacSecret: await crypto.subtle.generateKey(
+      {
+        name: "HMAC",
+        hash: "SHA-256",
+      } satisfies HmacKeyGenParams,
+      true,
+      ["sign", "verify"],
+    ),
+  };
+};

src/lib/shared/format/chunk.ts

@@ -1,7 +1,34 @@
-import { ENCRYPTION_OVERHEAD, CHUNK_SIZE, ENCRYPTED_CHUNK_SIZE } from "../constants";
+// Files are encrypted in chunks of `CHUNK_SIZE` bytes, each of which is stored as
+// `IV || ciphertext || tag`. Legacy files are encrypted as a single chunk.
 
-export * from "../../lib/modules/crypto";
+export const AES_GCM_IV_SIZE = 12;
+export const AES_GCM_TAG_SIZE = 16;
+export const ENCRYPTION_OVERHEAD = AES_GCM_IV_SIZE + AES_GCM_TAG_SIZE;
 
+export const CHUNK_SIZE = 4 * 1024 * 1024; // 4 MiB
+export const ENCRYPTED_CHUNK_SIZE = CHUNK_SIZE + ENCRYPTION_OVERHEAD;
+
+export const getChunkCount = (size: number) => {
+  return Math.ceil(size / CHUNK_SIZE);
+};
+
+export const getEncryptedSize = (size: number) => {
+  return size + getChunkCount(size) * ENCRYPTION_OVERHEAD;
+};
+
+export const getDecryptedSize = (encryptedSize: number, isLegacy: boolean) => {
+  if (isLegacy) {
+    return encryptedSize - ENCRYPTION_OVERHEAD;
+  }
+
+  const fullChunks = Math.floor(encryptedSize / ENCRYPTED_CHUNK_SIZE);
+  const lastChunkEncSize = encryptedSize % ENCRYPTED_CHUNK_SIZE;
+  return (
+    fullChunks * CHUNK_SIZE + (lastChunkEncSize > 0 ? lastChunkEncSize - ENCRYPTION_OVERHEAD : 0)
+  );
+};
+
+// Maps a range of the plaintext to the range of the encrypted chunks that contain it
 export const getEncryptedRange = (
   start: number,
   end: number,
@@ -26,15 +53,3 @@ export const getEncryptedRange = (
     end: Math.min((lastChunkIndex + 1) * ENCRYPTED_CHUNK_SIZE - 1, totalEncryptedSize - 1),
   };
 };
-
-export const getDecryptedSize = (encryptedSize: number, isLegacy: boolean) => {
-  if (isLegacy) {
-    return encryptedSize - ENCRYPTION_OVERHEAD;
-  }
-
-  const fullChunks = Math.floor(encryptedSize / ENCRYPTED_CHUNK_SIZE);
-  const lastChunkEncSize = encryptedSize % ENCRYPTED_CHUNK_SIZE;
-  return (
-    fullChunks * CHUNK_SIZE + (lastChunkEncSize > 0 ? lastChunkEncSize - ENCRYPTION_OVERHEAD : 0)
-  );
-};

src/lib/shared/format/index.ts

@@ -0,0 +1 @@
+export * from "./chunk";

src/lib/shared/http.ts

@@ -0,0 +1,35 @@
+export type RangeRequest = { start: number; end?: number } | { suffixLength: number };
+
+export interface ByteRange {
+  start: number;
+  end: number;
+  total: number;
+}
+
+// Only the first range is used if multiple ranges are requested
+export const parseRangeHeader = (value: string | null): RangeRequest | undefined => {
+  const match = value?.match(/^bytes=\s*(\d*)-(\d*)/);
+  if (!match) return undefined;
+
+  const [, start, end] = match;
+  if (start) {
+    return { start: parseInt(start, 10), end: end ? parseInt(end, 10) : undefined };
+  } else if (end) {
+    return { suffixLength: parseInt(end, 10) };
+  }
+};
+
+// Returns `null` if the range is not satisfiable
+export const resolveRange = (range: RangeRequest | undefined, total: number): ByteRange | null => {
+  if (!range) {
+    return { start: 0, end: total - 1, total };
+  }
+
+  const start = "suffixLength" in range ? Math.max(0, total - range.suffixLength) : range.start;
+  const end = "suffixLength" in range ? total - 1 : Math.min(range.end ?? total - 1, total - 1);
+  return start <= end ? { start, end, total } : null;
+};
+
+export const getContentRangeHeader = (range: ByteRange) => {
+  return { "Content-Range": `bytes ${range.start}-${range.end}/${range.total}` };
+};

src/lib/shared/serviceWorker.ts

@@ -1,3 +1,5 @@
+export const DECRYPTED_FILE_URL_PREFIX = "/_internal/decryptedFile/";
+
 export interface FileMetadata {
   isLegacy: boolean;
   dataKey: CryptoKey;

src/routes/(fullscreen)/client/pending/service.ts

@@ -1,4 +1,4 @@
-import { concatenateBuffers, exportRSAKey, digestMessage } from "#lib/modules/crypto/index.js";
+import { concatenateBuffers, exportRSAKey, digestMessage } from "#lib/shared/crypto/index.js";
 
 export { requestMasterKeyDownload } from "#lib/services/key.js";
 

src/routes/(fullscreen)/file/[id]/+page.svelte

@@ -6,8 +6,8 @@
   import { FullscreenDiv } from "#lib/components/atoms/index.js";
   import { Categories, IconEntryButton, TopBar } from "#lib/components/molecules/index.js";
   import { getFileInfo, type MaybeFileInfo } from "#lib/modules/filesystem/index.js";
-  import { captureVideoThumbnail } from "#lib/modules/thumbnail.js";
+  import { captureVideoThumbnail } from "#lib/client/media/thumbnail.js";
-  import { getFileDownloadState } from "#lib/modules/file/index.js";
+  import { getFileDownloadState } from "#lib/client/transfer/index.js";
   import { masterKeyStore } from "#lib/stores/index.js";
   import { HybridPromise } from "#lib/utils/index.js";
   import AddToCategoryBottomSheet from "./AddToCategoryBottomSheet.svelte";

src/routes/(fullscreen)/file/[id]/DownloadStatus.svelte

@@ -1,5 +1,5 @@
 <script lang="ts">
-  import { isFileDownloading, type FileDownloadState } from "#lib/modules/file/index.js";
+  import { isFileDownloading, type FileDownloadState } from "#lib/client/transfer/index.js";
   import { formatNetworkSpeed } from "#lib/utils/index.js";
 
   interface Props {

src/routes/(fullscreen)/file/[id]/service.ts

@@ -1,5 +1,5 @@
-import { storeFileThumbnailCache } from "#lib/modules/file/index.js";
+import { storeFileThumbnailCache } from "#lib/client/cache/index.js";
-import { prepareFileDecryption, getDecryptedFileUrl } from "#lib/serviceWorker/index.js";
+import { prepareFileDecryption, getDecryptedFileUrl } from "#lib/client/serviceWorker.js";
 import { requestFileThumbnailUpload } from "#lib/services/file.js";
 import { trpc } from "#trpc/client.js";
 

src/routes/(fullscreen)/file/downloads/+page.svelte

@@ -6,7 +6,7 @@
     getDownloadingFiles,
     clearDownloadedFiles,
     type FileDownloadState,
-  } from "#lib/modules/file/index.js";
+  } from "#lib/client/transfer/index.js";
   import { bulkGetFileInfo, type MaybeFileInfo } from "#lib/modules/filesystem/index.js";
   import { masterKeyStore } from "#lib/stores/index.js";
   import File from "./File.svelte";

src/routes/(fullscreen)/file/downloads/File.svelte

@@ -1,5 +1,5 @@
 <script lang="ts">
-  import type { FileDownloadState } from "#lib/modules/file/index.js";
+  import type { FileDownloadState } from "#lib/client/transfer/index.js";
   import type { SummarizedFileInfo } from "#lib/modules/filesystem/index.js";
   import { formatNetworkSpeed } from "#lib/utils/index.js";
 

src/routes/(fullscreen)/file/uploads/+page.svelte

@@ -1,7 +1,7 @@
 <script lang="ts">
   import { FullscreenDiv } from "#lib/components/atoms/index.js";
   import { TopBar } from "#lib/components/molecules/index.js";
-  import { getUploadingFiles, clearUploadedFiles } from "#lib/modules/file/index.js";
+  import { getUploadingFiles, clearUploadedFiles } from "#lib/client/transfer/index.js";
   import File from "./File.svelte";
 
   const uploadingFiles = getUploadingFiles();

src/routes/(fullscreen)/file/uploads/File.svelte

@@ -1,5 +1,5 @@
 <script lang="ts">
-  import type { FileUploadState } from "#lib/modules/file/index.js";
+  import type { FileUploadState } from "#lib/client/transfer/index.js";
   import { formatNetworkSpeed } from "#lib/utils/index.js";
 
   import IconPending from "~icons/material-symbols/pending";

src/routes/(fullscreen)/key/generate/service.ts

@@ -1,3 +1,4 @@
+import { deserializeClientKeys } from "#lib/modules/key.js";
 import {
   generateEncryptionKeyPair,
   generateSigningKeyPair,
@@ -10,8 +11,7 @@ import {
   makeAESKeyNonextractable,
   wrapHmacSecret,
   generateHmacSecret,
-} from "#lib/modules/crypto/index.js";
+} from "#lib/shared/crypto/index.js";
-import { deserializeClientKeys } from "#lib/modules/key.js";
 import { clientKeyStore } from "#lib/stores/index.js";
 
 export { requestLogout } from "#lib/services/auth.js";

src/routes/(fullscreen)/search/File.svelte

@@ -1,7 +1,7 @@
 <script lang="ts">
   import { ActionEntryButton } from "#lib/components/atoms/index.js";
   import { DirectoryEntryLabel } from "#lib/components/molecules/index.js";
-  import { getFileThumbnail } from "#lib/modules/file/index.js";
+  import { getFileThumbnail } from "#lib/client/cache/index.js";
   import type { SummarizedFileInfo } from "#lib/modules/filesystem/index.js";
   import { formatDateTime } from "#lib/utils/index.js";
 

src/routes/(fullscreen)/settings/cache/+page.svelte

@@ -2,11 +2,11 @@
   import { onMount } from "svelte";
   import { FullscreenDiv } from "#lib/components/atoms/index.js";
   import { TopBar } from "#lib/components/molecules/index.js";
-  import type { FileCacheIndex } from "#lib/indexedDB/index.js";
+  import type { FileCacheIndex } from "#lib/client/storage/indexedDB/index.js";
   import {
     getFileCacheIndex,
     deleteFileCache as doDeleteFileCache,
-  } from "#lib/modules/file/index.js";
+  } from "#lib/client/cache/index.js";
   import { bulkGetFileInfo, type MaybeFileInfo } from "#lib/modules/filesystem/index.js";
   import { masterKeyStore } from "#lib/stores/index.js";
   import { formatFileSize } from "#lib/utils/index.js";

src/routes/(fullscreen)/settings/cache/File.svelte

@@ -1,5 +1,5 @@
 <script lang="ts">
-  import type { FileCacheIndex } from "#lib/indexedDB/index.js";
+  import type { FileCacheIndex } from "#lib/client/storage/indexedDB/index.js";
   import type { MaybeFileInfo } from "#lib/modules/filesystem/index.js";
   import { formatDate, formatFileSize } from "#lib/utils/index.js";
 

src/routes/(fullscreen)/settings/thumbnail/+page.svelte

@@ -3,7 +3,7 @@
   import { goto } from "$app/navigation";
   import { BottomDiv, Button, FullscreenDiv } from "#lib/components/atoms/index.js";
   import { IconEntryButton, TopBar } from "#lib/components/molecules/index.js";
-  import { deleteAllFileThumbnailCaches } from "#lib/modules/file/index.js";
+  import { deleteAllFileThumbnailCaches } from "#lib/client/cache/index.js";
   import type { MaybeFileInfo } from "#lib/modules/filesystem/index.js";
   import { masterKeyStore } from "#lib/stores/index.js";
   import { sortEntries } from "#lib/utils/index.js";

src/routes/(fullscreen)/settings/thumbnail/service.ts

@@ -1,8 +1,8 @@
 import { limitFunction } from "p-limit";
 import { SvelteMap } from "svelte/reactivity";
-import { storeFileThumbnailCache } from "#lib/modules/file/index.js";
+import { storeFileThumbnailCache } from "#lib/client/cache/index.js";
+import { generateThumbnail } from "#lib/client/media/thumbnail.js";
 import { getFileInfo, type FileInfo } from "#lib/modules/filesystem/index.js";
-import { generateThumbnail } from "#lib/modules/thumbnail.js";
 import { requestFileDownload, requestFileThumbnailUpload } from "#lib/services/file.js";
 import { HybridPromise, Scheduler } from "#lib/utils/index.js";
 import type { RouterOutputs } from "#trpc/router.server.js";

src/routes/(main)/category/[[id]]/+page.svelte

@@ -3,7 +3,7 @@
   import { CheckBox, RowVirtualizer } from "#lib/components/atoms/index.js";
   import { SubCategories, TopBar } from "#lib/components/molecules/index.js";
   import { CategoryCreateModal } from "#lib/components/organisms/index.js";
-  import { updateCategoryInfo } from "#lib/indexedDB/index.js";
+  import { updateCategoryInfo } from "#lib/client/storage/indexedDB/index.js";
   import { getCategoryInfo, type MaybeCategoryInfo } from "#lib/modules/filesystem/index.js";
   import { masterKeyStore } from "#lib/stores/index.js";
   import { HybridPromise, sortEntries } from "#lib/utils/index.js";

src/routes/(main)/category/[[id]]/File.svelte

@@ -1,7 +1,7 @@
 <script lang="ts">
   import { ActionEntryButton } from "#lib/components/atoms/index.js";
   import { DirectoryEntryLabel } from "#lib/components/molecules/index.js";
-  import { getFileThumbnail } from "#lib/modules/file/index.js";
+  import { getFileThumbnail } from "#lib/client/cache/index.js";
   import type { CategoryFileInfo } from "#lib/modules/filesystem/index.js";
   import { formatDateTime } from "#lib/utils/index.js";
   import type { SelectedFile } from "./service.svelte";

src/routes/(main)/category/[[id]]/service.svelte.ts

@@ -1,6 +1,6 @@
 import { getContext, setContext } from "svelte";
-import { encryptString } from "#lib/modules/crypto/index.js";
 import type { SelectedCategory } from "#lib/components/molecules/index.js";
+import { encryptString } from "#lib/shared/crypto/index.js";
 import { trpc } from "#trpc/client.js";
 
 export { requestCategoryCreation, requestFileRemovalFromCategory } from "#lib/services/category.js";

src/routes/(main)/directory/[[id]]/DirectoryEntries/DirectoryEntries.svelte

@@ -1,7 +1,7 @@
 <script lang="ts">
   import { ActionEntryButton, RowVirtualizer } from "#lib/components/atoms/index.js";
   import { DirectoryEntryLabel } from "#lib/components/molecules/index.js";
-  import { getUploadingFiles, type LiveFileUploadState } from "#lib/modules/file/index.js";
+  import { getUploadingFiles, type LiveFileUploadState } from "#lib/client/transfer/index.js";
   import type { DirectoryInfo } from "#lib/modules/filesystem/index.js";
   import { sortEntries } from "#lib/utils/index.js";
   import File from "./File.svelte";

src/routes/(main)/directory/[[id]]/DirectoryEntries/File.svelte

@@ -1,7 +1,7 @@
 <script lang="ts">
   import { ActionEntryButton } from "#lib/components/atoms/index.js";
   import { DirectoryEntryLabel } from "#lib/components/molecules/index.js";
-  import { getFileThumbnail } from "#lib/modules/file/index.js";
+  import { getFileThumbnail } from "#lib/client/cache/index.js";
   import type { SummarizedFileInfo } from "#lib/modules/filesystem/index.js";
   import { formatDateTime } from "#lib/utils/index.js";
   import type { SelectedEntry } from "../service.svelte";

src/routes/(main)/directory/[[id]]/DirectoryEntries/UploadingFile.svelte

@@ -1,5 +1,5 @@
 <script lang="ts">
-  import type { LiveFileUploadState } from "#lib/modules/file/index.js";
+  import type { LiveFileUploadState } from "#lib/client/transfer/index.js";
   import { formatNetworkSpeed } from "#lib/utils/index.js";
 
   import IconDraft from "~icons/material-symbols/draft";

src/routes/(main)/directory/[[id]]/DownloadStatusCard.svelte

@@ -1,5 +1,5 @@
 <script lang="ts">
-  import { getDownloadingFiles } from "#lib/modules/file/index.js";
+  import { getDownloadingFiles } from "#lib/client/transfer/index.js";
 
   interface Props {
     onclick: () => void;

src/routes/(main)/directory/[[id]]/UploadStatusCard.svelte

@@ -1,5 +1,5 @@
 <script lang="ts">
-  import { getUploadingFiles } from "#lib/modules/file/index.js";
+  import { getUploadingFiles } from "#lib/client/transfer/index.js";
 
   interface Props {
     onclick: () => void;

src/routes/(main)/directory/[[id]]/service.svelte.ts

@@ -1,19 +1,19 @@
 import { getContext, setContext } from "svelte";
-import { storeHmacSecrets } from "#lib/indexedDB/index.js";
-import {
-  generateDataKey,
-  wrapDataKey,
-  unwrapHmacSecret,
-  encryptString,
-} from "#lib/modules/crypto/index.js";
 import {
   storeFileCache,
   deleteFileCache,
   storeFileThumbnailCache,
   deleteFileThumbnailCache,
-  uploadFile,
+} from "#lib/client/cache/index.js";
-} from "#lib/modules/file/index.js";
+import { storeHmacSecrets } from "#lib/client/storage/indexedDB/index.js";
+import { uploadFile } from "#lib/client/transfer/index.js";
 import type { DataKey } from "#lib/modules/filesystem/index.js";
+import {
+  generateDataKey,
+  wrapDataKey,
+  unwrapHmacSecret,
+  encryptString,
+} from "#lib/shared/crypto/index.js";
 import { hmacSecretStore, type MasterKey, type HmacSecret } from "#lib/stores/index.js";
 import { trpc } from "#trpc/client.js";
 

src/routes/(main)/favorites/File.svelte

@@ -1,7 +1,7 @@
 <script lang="ts">
   import { ActionEntryButton } from "#lib/components/atoms/index.js";
   import { DirectoryEntryLabel } from "#lib/components/molecules/index.js";
-  import { getFileThumbnail } from "#lib/modules/file/index.js";
+  import { getFileThumbnail } from "#lib/client/cache/index.js";
   import type { SummarizedFileInfo } from "#lib/modules/filesystem/index.js";
   import { formatDateTime } from "#lib/utils/index.js";
 

src/routes/(main)/home/service.ts

@@ -1,4 +1,4 @@
-import { getAllFileInfos } from "#lib/indexedDB/index.js";
+import { getAllFileInfos } from "#lib/client/storage/indexedDB/index.js";
 
 export const requestFreshMediaFilesRetrieval = async (limit = 8) => {
   const files = await getAllFileInfos();

src/routes/+layout.svelte

@@ -1,5 +1,5 @@
 <script lang="ts">
-  import { getDownloadingFiles, getUploadingFiles } from "#lib/modules/file/index.js";
+  import { getDownloadingFiles, getUploadingFiles } from "#lib/client/transfer/index.js";
   import "../app.css";
 
   let { children } = $props();

src/routes/api/file/[id]/[[thumbnail=thumbnail]]/download/+server.ts

@@ -1,9 +1,9 @@
 import { error } from "@sveltejs/kit";
 import { z } from "zod";
-import { parseRangeHeader, getContentRangeHeader } from "#lib/modules/http.js";
 import { authorize } from "#lib/server/auth.js";
 import { handleAppErrors } from "#lib/server/http.js";
 import { FileService } from "#lib/server/services/index.js";
+import { parseRangeHeader, getContentRangeHeader } from "#lib/shared/http.js";
 import type { RequestEvent, RequestHandler } from "./$types";
 
 const downloadHandler = async ({ locals, params, request }: RequestEvent) => {

src/service-worker/constants.ts

@@ -1 +0,0 @@
-export * from "../lib/constants";

src/service-worker/handlers/decryptFile.ts

@@ -1,14 +1,25 @@
-import { DECRYPTED_FILE_URL_PREFIX, CHUNK_SIZE, ENCRYPTED_CHUNK_SIZE } from "../constants";
+import { getFile } from "#lib/client/storage/opfs.js";
-import { decryptChunk, getEncryptedRange, getDecryptedSize } from "../modules/crypto";
+import { decryptChunk } from "#lib/shared/crypto/index.js";
-import { parseRangeHeader, getContentRangeHeader } from "../modules/http";
+import {
+  CHUNK_SIZE,
+  ENCRYPTED_CHUNK_SIZE,
+  getDecryptedSize,
+  getEncryptedRange,
+} from "#lib/shared/format/index.js";
+import {
+  getContentRangeHeader,
+  parseRangeHeader,
+  resolveRange,
+  type ByteRange,
+  type RangeRequest,
+} from "#lib/shared/http.js";
+import { DECRYPTED_FILE_URL_PREFIX, type FileMetadata } from "#lib/shared/serviceWorker.js";
 import { getFileMetadata } from "../modules/metadata";
-import { getFile } from "../modules/opfs";
-import type { FileMetadata } from "../types";
 
 const createResponse = (
   stream: ReadableStream<Uint8Array>,
   isRangeRequest: boolean,
-  range: { start: number; end: number; total: number },
+  range: ByteRange,
   contentType?: string,
   downloadFilename?: string,
 ) => {
@@ -33,22 +44,28 @@ const createResponse = (
   });
 };
 
+const createRangeNotSatisfiableResponse = (total: number) => {
+  return new Response("Invalid range", {
+    status: 416,
+    headers: { "Content-Range": `bytes */${total}` },
+  });
+};
+
 const streamFromOpfs = async (
   file: File,
   metadata?: FileMetadata,
-  range?: { start?: number; end?: number },
+  rangeRequest?: RangeRequest,
   downloadFilename?: string,
 ) => {
-  const start = range?.start ?? 0;
+  const range = resolveRange(rangeRequest, file.size);
-  const end = range?.end ?? file.size - 1;
+  if (!range) {
-  if (start > end || start < 0 || end >= file.size) {
+    return createRangeNotSatisfiableResponse(file.size);
-    return new Response("Invalid range", { status: 416 });
   }
 
   return createResponse(
-    file.slice(start, end + 1).stream(),
+    file.slice(range.start, range.end + 1).stream(),
-    !!range,
+    !!rangeRequest,
-    { start, end, total: file.size },
+    range,
     metadata?.contentType,
     downloadFilename,
   );
@@ -57,16 +74,16 @@ const streamFromOpfs = async (
 const streamFromServer = async (
   id: number,
   metadata: FileMetadata,
-  range?: { start?: number; end?: number },
+  rangeRequest?: RangeRequest,
   downloadFilename?: string,
 ) => {
   const totalSize = getDecryptedSize(metadata.encContentSize, metadata.isLegacy);
-  const start = range?.start ?? 0;
+  const range = resolveRange(rangeRequest, totalSize);
-  const end = range?.end ?? totalSize - 1;
+  if (!range) {
-  if (start > end || start < 0 || end >= totalSize) {
+    return createRangeNotSatisfiableResponse(totalSize);
-    return new Response("Invalid range", { status: 416 });
   }
 
+  const { start, end } = range;
   const encryptedRange = getEncryptedRange(start, end, metadata.encContentSize, metadata.isLegacy);
   const apiResponse = await fetch(`/api/file/${id}/download`, {
     headers: { Range: `bytes=${encryptedRange.start}-${encryptedRange.end}` },
@@ -85,9 +102,10 @@ const streamFromServer = async (
           controller.close();
         },
       }),
-      !!range,
+      !!rangeRequest,
-      { start, end, total: totalSize },
+      range,
       metadata.contentType,
+      downloadFilename,
     );
   }
 
@@ -124,8 +142,8 @@ const streamFromServer = async (
 
   return createResponse(
     apiResponse.body.pipeThrough(decryptingStream),
-    !!range,
+    !!rangeRequest,
-    { start, end, total: totalSize },
+    range,
     metadata.contentType,
     downloadFilename,
   );

src/service-worker/index.ts

@@ -1,8 +1,11 @@
 import { self } from "$app/service-worker";
-import { DECRYPTED_FILE_URL_PREFIX } from "./constants";
+import {
+  DECRYPTED_FILE_URL_PREFIX,
+  type ServiceWorkerMessage,
+  type ServiceWorkerResponse,
+} from "#lib/shared/serviceWorker.js";
 import { decryptFile } from "./handlers";
 import { fileMetadataStore } from "./stores";
-import type { ServiceWorkerMessage, ServiceWorkerResponse } from "./types";
 
 self.addEventListener("message", (event) => {
   const message: ServiceWorkerMessage = event.data;

src/service-worker/modules/http.ts

@@ -1 +0,0 @@
-export * from "../../lib/modules/http";

src/service-worker/modules/metadata.ts

@@ -1,6 +1,6 @@
 import { self } from "$app/service-worker";
+import type { FileMetadata, ServiceWorkerResponse } from "#lib/shared/serviceWorker.js";
 import { fileMetadataStore } from "../stores";
-import type { FileMetadata, ServiceWorkerResponse } from "../types";
 
 const METADATA_REQUEST_TIMEOUT_MS = 3000;
 

src/service-worker/modules/opfs.ts

@@ -1 +0,0 @@
-export * from "../../lib/modules/opfs";

src/service-worker/stores.ts

@@ -1,4 +1,4 @@
-import type { FileMetadata } from "./types";
+import type { FileMetadata } from "#lib/shared/serviceWorker.js";
 
 const MAX_FILE_METADATA_ENTRIES = 32;
 

src/service-worker/types.ts

@@ -1 +0,0 @@
-export * from "../lib/serviceWorker/types";

tests/server/download.test.ts

@@ -39,6 +39,25 @@ describe("createEncContentStream", () => {
     expect(await read(encContentStream)).toBe("2345");
   });
 
+  it("serves suffix ranges", async () => {
+    const path = await createFile("0123456789");
+
+    const { encContentStream, range } = await createEncContentStream(path, undefined, {
+      suffixLength: 3,
+    });
+
+    expect(range).toEqual({ start: 7, end: 9, total: 10 });
+    expect(await read(encContentStream)).toBe("789");
+  });
+
+  it("rejects unsatisfiable ranges", async () => {
+    const path = await createFile("0123456789");
+
+    await expect(createEncContentStream(path, undefined, { start: 10 })).rejects.toMatchObject({
+      code: "RANGE_NOT_SATISFIABLE",
+    });
+  });
+
   it("prepends the legacy IV to the content", async () => {
     const path = await createFile("6789");
 

tests/unit/crypto.test.ts

@@ -7,7 +7,7 @@ import {
   encryptChunk,
   encryptString,
   generateDataKey,
-} from "#lib/modules/crypto/index.js";
+} from "#lib/shared/crypto/index.js";
 
 describe("base64", () => {
   it("round-trips large buffers", () => {

tests/unit/range.test.ts

@@ -1,7 +1,13 @@
 import { describe, expect, it } from "vitest";
-import { CHUNK_SIZE, ENCRYPTED_CHUNK_SIZE, ENCRYPTION_OVERHEAD } from "#lib/constants/index.js";
+import {
-import { getContentRangeHeader, parseRangeHeader } from "#lib/modules/http.js";
+  CHUNK_SIZE,
-import { getDecryptedSize, getEncryptedRange } from "../../src/service-worker/modules/crypto";
+  ENCRYPTED_CHUNK_SIZE,
+  ENCRYPTION_OVERHEAD,
+  getDecryptedSize,
+  getEncryptedRange,
+  getEncryptedSize,
+} from "#lib/shared/format/index.js";
+import { getContentRangeHeader, parseRangeHeader, resolveRange } from "#lib/shared/http.js";
 
 describe("parseRangeHeader", () => {
   it("parses byte ranges", () => {
@@ -9,6 +15,33 @@ describe("parseRangeHeader", () => {
     expect(parseRangeHeader("bytes=0-")).toEqual({ start: 0, end: undefined });
     expect(parseRangeHeader("bytes=10-20")).toEqual({ start: 10, end: 20 });
     expect(parseRangeHeader("bytes=10-20, 30-40")).toEqual({ start: 10, end: 20 });
+    expect(parseRangeHeader("bytes=-500")).toEqual({ suffixLength: 500 });
+  });
+
+  it("ignores invalid ranges", () => {
+    expect(parseRangeHeader("bytes=-")).toBeUndefined();
+    expect(parseRangeHeader("items=0-1")).toBeUndefined();
+  });
+});
+
+describe("resolveRange", () => {
+  it("resolves the whole content without a range", () => {
+    expect(resolveRange(undefined, 100)).toEqual({ start: 0, end: 99, total: 100 });
+  });
+
+  it("clamps the end to the content size", () => {
+    expect(resolveRange({ start: 10, end: 1000 }, 100)).toEqual({ start: 10, end: 99, total: 100 });
+    expect(resolveRange({ start: 10 }, 100)).toEqual({ start: 10, end: 99, total: 100 });
+  });
+
+  it("resolves suffix ranges", () => {
+    expect(resolveRange({ suffixLength: 10 }, 100)).toEqual({ start: 90, end: 99, total: 100 });
+    expect(resolveRange({ suffixLength: 1000 }, 100)).toEqual({ start: 0, end: 99, total: 100 });
+  });
+
+  it("rejects unsatisfiable ranges", () => {
+    expect(resolveRange({ start: 100 }, 100)).toBeNull();
+    expect(resolveRange({ start: 20, end: 10 }, 100)).toBeNull();
   });
 
   it("formats Content-Range", () => {
@@ -19,13 +52,13 @@ describe("parseRangeHeader", () => {
 });
 
 describe("encrypted chunk layout", () => {
-  const encryptedSizeOf = (size: number) =>
-    size + Math.ceil(size / CHUNK_SIZE) * ENCRYPTION_OVERHEAD;
-
   it.each([1, CHUNK_SIZE - 1, CHUNK_SIZE, CHUNK_SIZE + 1, 3 * CHUNK_SIZE + 12345])(
     "computes the decrypted size of %i bytes",
     (size) => {
-      expect(getDecryptedSize(encryptedSizeOf(size), false)).toBe(size);
+      expect(getEncryptedSize(size)).toBe(
+        size + Math.ceil(size / CHUNK_SIZE) * ENCRYPTION_OVERHEAD,
+      );
+      expect(getDecryptedSize(getEncryptedSize(size), false)).toBe(size);
     },
   );
 
@@ -35,7 +68,7 @@ describe("encrypted chunk layout", () => {
 
   it("maps a plaintext range to whole encrypted chunks", () => {
     const totalSize = 3 * CHUNK_SIZE + 100;
-    const totalEncryptedSize = encryptedSizeOf(totalSize);
+    const totalEncryptedSize = getEncryptedSize(totalSize);
 
     expect(getEncryptedRange(0, 10, totalEncryptedSize, false)).toEqual({
       firstChunkIndex: 0,