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quak/test/download/download.test.ts
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Make lint and test phases of the Dockerfile (closes #96)
Follows the template: Dockerfile.lint is gone; the Dockerfile has a lint
phase (eslint, prettier --check .) and a test phase (vitest, run as the
node user, which the not-writable-directory tests need), and its
last stage compiles and depends on both. script/lint and script/test
build one phase each with --no-cache; script/docker and script/cibuild
pass --no-cache, so CHECK_EPOCH and LINT_EPOCH are removed.
script/cibuild is the single image build, so CI runs lint and the tests
once each. The tests that checked the old layout are deleted,
REPO_POLICIES.md is re-copied and the README describes the new layout.

Model: opus-5-5
2026-09-23 05:15:41 +00:00

1786 lines
74 KiB
TypeScript

/**
* Tests for `downloadFile` and `downloadThumbnail`.
*
* These functions combine the ApiClient's streaming download with the
* secretstream pull decryption to recover the plaintext file content and
* write it to disk.
*
* The encrypted body returned by the CDN is a concatenation of
* secretstream ciphertext chunks. Each chunk is at most
* `STREAM_CHUNK_SIZE + STREAM_CHUNK_OVERHEAD` bytes (4 MiB + 17 bytes).
* The download function buffers incoming network data, splits it on the
* chunk boundary, and feeds each piece to `pullStreamChunk`.
*
* Two contracts are load-bearing for anyone using this library as a backup
* tool, and both are documented by the tests below:
*
* 1. **Truncation is an error, never a short file.** Only the final chunk of
* a secretstream carries `TAG_FINAL`. A download cut short by a dropped
* connection still decrypts cleanly up to the last whole chunk, so without
* an explicit `TAG_FINAL` check a truncated body is indistinguishable from
* a complete one. `streamDecrypt` therefore refuses to return unless the
* stream ended on `TAG_FINAL`, and the error says the stream was truncated.
* A transfer that stopped part-way through a chunk is reported the same
* way, since a final chunk that arrived in full always authenticates.
*
* 2. **The destination path is written atomically.** Plaintext goes to a
* temporary sibling file first and is `rename`d into place only after the
* whole stream has decrypted and verified. A caller that sees no exception
* can rely on the destination containing the complete, authenticated file;
* a caller that sees an exception can rely on the destination being
* untouched — whatever was there before is still there, byte for byte, and
* no partial file has appeared. This matters because `runBackup` skips any
* existing non-empty file, so a partial write would be treated as complete
* forever after. The staging file and the rename are observed directly (see
* the `rename` hook below), not inferred from an empty directory.
*
* 3. **A failed transfer is retried as a whole.** A download is a request, a
* stream consumption, and a decryption, and only the first of those three
* happens inside `ApiClient`. A socket reset after the response headers
* have arrived therefore surfaces here, in the download layer — and that is
* the dominant failure mode for multi-megabyte photos over a CDN. So the
* entire sequence is retried as one unit, not just the request. The
* secretstream pull state is not resumable and there is no Range support,
* so a retry starts the file over from byte zero.
*
* These tests build synthetic encrypted files using sodium's push API,
* serve them from a mock fetch, and verify the decrypted output on disk.
*/
import {
chmodSync,
existsSync,
mkdirSync,
readdirSync,
readFileSync,
rmSync,
mkdtempSync,
writeFileSync,
} from "node:fs";
import { dirname, join } from "node:path";
import { tmpdir } from "node:os";
import { createHash } from "node:crypto";
import sodium from "libsodium-wrappers-sumo";
import { zipSync } from "fflate";
import {
beforeAll,
beforeEach,
afterAll,
describe,
expect,
it,
vi,
} from "vitest";
import { init, toBase64, STREAM_CHUNK_SIZE } from "../../src/crypto/index.js";
import { ApiClient } from "../../src/api/client.js";
import { ApiError, TruncatedStreamError } from "../../src/errors.js";
import type { RetryOptions } from "../../src/retry.js";
import {
downloadFile,
downloadThumbnail,
writeAtomic,
} from "../../src/download/index.js";
import type { EnteFile, FileMetadata } from "../../src/model/types.js";
// ---------------------------------------------------------------------------
// Test helpers
// ---------------------------------------------------------------------------
/**
* `rename` is intercepted so that the tests can observe — and fail — the
* final step of the atomic write.
*
* Every other failure in this file is injected inside `streamDecrypt`, which
* runs before anything is written to disk. Those tests therefore cannot tell
* an atomic write from a plain `writeFile`: under both, nothing was ever
* created, so an empty directory proves nothing about cleanup. This hook is
* what closes that gap. It records each rename the downloader performs,
* including whether the source existed at that moment (i.e. that the staged
* temp file really was written), and can be told to fail the rename so the
* cleanup path runs with a temp file genuinely on disk.
*
* `vi.hoisted` is required: `vi.mock` factories are hoisted above the imports,
* so a plain module-level `const` would still be in its temporal dead zone by
* the time the factory runs.
*/
const renameHook = vi.hoisted(() => ({
calls: [] as { from: string; to: string; sourceExisted: boolean }[],
failWith: null as Error | null,
}));
/**
* `open` is wrapped so the tests can observe the durability fsyncs the atomic
* writer performs — which are otherwise invisible: an fsync leaves no trace in
* the file's contents. Each `FileHandle.sync()` is recorded, and rename and
* sync events are appended to a single ordered `events` log so a test can pin
* the sequence "fsync the temp file, rename, fsync the directory" that makes a
* write survive a power cut. The flag the handle was opened with distinguishes
* the temp file (`w`) from its containing directory (`r`).
*/
const durabilityHook = vi.hoisted(() => ({
events: [] as string[],
}));
/**
* `FileHandle.write` is wrapped so the tests can watch the streaming decrypt
* path put plaintext on disk one chunk at a time. This is the direct evidence
* that memory is bounded by the chunk size and not the file size: a buffered
* downloader would hand the whole file to a single write, whereas the streaming
* one issues one write per secretstream chunk, none larger than
* `STREAM_CHUNK_SIZE`. Each write records the temp path it targeted and its
* length. `writeFile` (which the whole-buffer `writeAtomic` uses) is a distinct
* native call and does not go through this method, so only the streaming path
* is observed here.
*/
const writeHook = vi.hoisted(() => ({
writes: [] as { path: string; length: number }[],
}));
vi.mock("node:fs/promises", async (importOriginal) => {
const actual = await importOriginal<typeof import("node:fs/promises")>();
const { existsSync: sourceExists } = await import("node:fs");
return {
...actual,
open: async (
path: Parameters<typeof actual.open>[0],
flags?: Parameters<typeof actual.open>[1],
...rest: unknown[]
): Promise<Awaited<ReturnType<typeof actual.open>>> => {
const handle = await actual.open(
path,
flags as Parameters<typeof actual.open>[1],
...(rest as []),
);
const realSync = handle.sync.bind(handle);
handle.sync = async (): Promise<void> => {
durabilityHook.events.push(`sync:${String(flags)}:${path}`);
await realSync();
};
const realWrite = handle.write.bind(handle);
handle.write = (async (
data: unknown,
...rest2: unknown[]
): Promise<unknown> => {
if (data instanceof Uint8Array) {
writeHook.writes.push({
path: String(path),
length: data.length,
});
}
return (realWrite as (...a: unknown[]) => Promise<unknown>)(
data,
...rest2,
);
}) as typeof handle.write;
return handle;
},
rename: async (from: string, to: string): Promise<void> => {
renameHook.calls.push({
from,
to,
sourceExisted: sourceExists(from),
});
durabilityHook.events.push(`rename:${to}`);
if (renameHook.failWith !== null) {
throw renameHook.failWith;
}
await actual.rename(from, to);
},
};
});
/**
* `chunkHashUpdate` is wrapped to record the length of every piece hashed, so
* a test can show that a live photo entry reaches the hash in pieces far
* smaller than the entry, rather than decompressed whole first.
*/
const hashHook = vi.hoisted(() => ({
lengths: [] as number[],
}));
vi.mock("../../src/crypto/index.js", async (importOriginal) => {
const actual =
await importOriginal<typeof import("../../src/crypto/index.js")>();
return {
...actual,
chunkHashUpdate: (
...args: Parameters<typeof actual.chunkHashUpdate>
): void => {
hashHook.lengths.push(args[1].length);
actual.chunkHashUpdate(...args);
},
};
});
beforeEach(() => {
hashHook.lengths.length = 0;
renameHook.calls.length = 0;
renameHook.failWith = null;
durabilityHook.events.length = 0;
writeHook.writes.length = 0;
});
let testDir: string;
beforeAll(async () => {
await init();
await sodium.ready;
testDir = mkdtempSync(join(tmpdir(), "quak-test-"));
});
afterAll(() => {
if (testDir && existsSync(testDir)) {
rmSync(testDir, { recursive: true, force: true });
}
});
/**
* Deterministic stand-in for random test payloads.
*
* Fixture *content* is never load-bearing here — the assertions turn on
* length, framing, and the secretstream tag — but it must not be a constant
* fill either, or a downloader that reordered or repeated chunks would still
* produce the expected bytes. A seeded linear congruential generator gives
* both: byte patterns that differ across every offset and seed, reproducible
* on any machine, which is what the README asks of fixtures.
*
* It is also the difference between a fast suite and a broken one.
* `sodium.randombytes_buf` goes through the wasm wrapper a byte at a time and
* costs roughly 20 seconds for the 4 MiB chunk below — about two hundred
* times what it costs to encrypt the same buffer, and on its own enough to
* push `make test` past the 90-second `timeout` in the `test` phase of the
* `Dockerfile`. This loop fills
* 4 MiB in a few milliseconds.
*/
const patternBytes = (length: number, seed: number): Uint8Array => {
const out = new Uint8Array(length);
let x = seed >>> 0;
for (let i = 0; i < length; i++) {
// Numerical Recipes' LCG constants; the high byte is used because
// the low bits of an LCG have short periods.
x = (Math.imul(x, 1664525) + 1013904223) >>> 0;
out[i] = (x >>> 24) & 0xff;
}
return out;
};
/**
* Encrypt `plaintext` as a secretstream file body (single chunk with
* TAG_FINAL). Returns the key, header, and ciphertext that the mock CDN
* will serve.
*/
const encryptFileBody = (
plaintext: Uint8Array,
key: Uint8Array,
): { header: Uint8Array; ciphertext: Uint8Array } => {
const push = sodium.crypto_secretstream_xchacha20poly1305_init_push(key);
const ciphertext = sodium.crypto_secretstream_xchacha20poly1305_push(
push.state,
plaintext,
null,
sodium.crypto_secretstream_xchacha20poly1305_TAG_FINAL,
);
return { header: push.header, ciphertext };
};
/**
* Encrypt a body that spans more than one secretstream chunk, the way the
* server does for files larger than the 4 MiB plaintext chunk size.
*
* Framing matters here: the downloader splits the byte stream on fixed
* `STREAM_CHUNK_SIZE + STREAM_CHUNK_OVERHEAD` boundaries, so every chunk
* except the last must carry exactly `STREAM_CHUNK_SIZE` plaintext bytes.
* Only the last chunk is tagged `TAG_FINAL`; the leading ones are
* `TAG_MESSAGE`.
*
* Returns the header, the concatenated body, the plaintext it decrypts to,
* and `finalChunkOffset` — the byte offset at which the `TAG_FINAL` chunk
* begins, so a test can slice it off to simulate a connection that dropped
* before the end of the file.
*/
const encryptMultiChunkBody = (
key: Uint8Array,
leadingChunks: number,
finalChunkPlainSize: number,
): {
header: Uint8Array;
body: Uint8Array;
plaintext: Uint8Array;
finalChunkOffset: number;
} => {
const push = sodium.crypto_secretstream_xchacha20poly1305_init_push(key);
const cipherParts: Uint8Array[] = [];
const plainParts: Uint8Array[] = [];
for (let i = 0; i < leadingChunks; i++) {
const plain = patternBytes(STREAM_CHUNK_SIZE, i + 1);
plainParts.push(plain);
cipherParts.push(
sodium.crypto_secretstream_xchacha20poly1305_push(
push.state,
plain,
null,
sodium.crypto_secretstream_xchacha20poly1305_TAG_MESSAGE,
),
);
}
const finalPlain = patternBytes(finalChunkPlainSize, leadingChunks + 1);
plainParts.push(finalPlain);
const finalCipher = sodium.crypto_secretstream_xchacha20poly1305_push(
push.state,
finalPlain,
null,
sodium.crypto_secretstream_xchacha20poly1305_TAG_FINAL,
);
const finalChunkOffset = cipherParts.reduce((n, c) => n + c.length, 0);
cipherParts.push(finalCipher);
return {
header: push.header,
body: concat(cipherParts),
plaintext: concat(plainParts),
finalChunkOffset,
};
};
const concat = (parts: Uint8Array[]): Uint8Array => {
const total = parts.reduce((n, p) => n + p.length, 0);
const out = new Uint8Array(total);
let offset = 0;
for (const p of parts) {
out.set(p, offset);
offset += p.length;
}
return out;
};
const buildMockEnteFile = (
key: Uint8Array,
fileHeader: Uint8Array,
thumbHeader: Uint8Array,
): EnteFile => ({
id: 999,
collectionID: 1,
ownerID: 1,
key,
metadata: {
title: "test-photo.jpg",
fileType: "image",
creationTime: 0,
modificationTime: 0,
} as FileMetadata,
file: { decryptionHeader: toBase64(fileHeader) },
thumbnail: { decryptionHeader: toBase64(thumbHeader) },
updationTime: 0,
});
const mockFetchForBody = (body: Uint8Array) => {
const fake = async (): Promise<Response> =>
new Response(body, { status: 200 });
return fake as typeof globalThis.fetch;
};
/**
* Encrypt a body consisting of one chunk that is *not* tagged TAG_FINAL.
*
* This is the cheap way to present a stream that ended without its final
* chunk: the downloader pulls it, authenticates it, and finds the stream
* over on a TAG_MESSAGE chunk — the same terminal condition as a large file
* whose last chunk was lost, without paying for a 4 MiB fixture. The
* multi-chunk fixture above covers the realistic wire shape; this one is
* used where the test is really about what happens on disk afterwards.
*/
const encryptNonFinalBody = (
plaintext: Uint8Array,
key: Uint8Array,
): { header: Uint8Array; ciphertext: Uint8Array } => {
const push = sodium.crypto_secretstream_xchacha20poly1305_init_push(key);
const ciphertext = sodium.crypto_secretstream_xchacha20poly1305_push(
push.state,
plaintext,
null,
sodium.crypto_secretstream_xchacha20poly1305_TAG_MESSAGE,
);
return { header: push.header, ciphertext };
};
/**
* Compare file contents by digest rather than with `toEqual`. Vitest's deep
* equality walks multi-megabyte buffers byte by byte, which costs seconds on
* the 4 MiB fixtures; a digest comparison is exact and effectively free.
*/
const expectSameBytes = (actual: Uint8Array, expected: Uint8Array): void => {
expect(actual.length).toBe(expected.length);
expect(createHash("sha256").update(actual).digest("hex")).toBe(
createHash("sha256").update(expected).digest("hex"),
);
};
/**
* A multi-chunk fixture shared by the truncation tests: one full 4 MiB
* `TAG_MESSAGE` chunk followed by a small `TAG_FINAL` chunk. It is built once
* and shared because encrypting 4 MiB costs about 100ms. Its plaintext is
* generated rather than drawn from the CSPRNG, which is what keeps that
* encryption the whole cost of the fixture.
*/
let multiChunk: ReturnType<typeof encryptMultiChunkBody>;
let multiChunkKey: Uint8Array;
beforeAll(() => {
multiChunkKey = sodium.crypto_secretstream_xchacha20poly1305_keygen();
multiChunk = encryptMultiChunkBody(multiChunkKey, 1, 1024);
});
/** An error shaped like a Node transport failure: the errno is on `.code`. */
const errnoError = (code: string, message = code): Error =>
Object.assign(new Error(message), { code });
/**
* A retry policy with the waiting removed, used by every fixture in this
* file. Backoff arithmetic belongs to `test/retry/retry.test.ts`; here the
* only interesting quantity is how many requests a download issued, so the
* injected `sleep` returns immediately and nothing in this file waits.
*/
const noWait: RetryOptions = {
sleep: () => Promise.resolve(),
random: () => 0,
};
/**
* One scripted outcome for a single request to the CDN.
*
* - `body` — a complete response body.
* - `status` — an HTTP error response.
* - `reset` — a response whose headers arrive, whose body delivers `bytes`,
* and which then dies with a socket reset. This is the failure that
* motivates retrying the download rather than the request: by the time it
* happens `ApiClient` has already returned successfully.
*/
type BodyStep =
| { kind: "body"; bytes: Uint8Array }
| { kind: "status"; status: number }
| { kind: "reset"; bytes: Uint8Array };
/**
* A fetch that serves one scripted step per call and counts the calls. It
* deliberately refuses to serve more requests than it was given steps for, so
* a retry loop that ran away is a test failure rather than a silent success.
*/
const scriptedCdnFetch = (
...steps: BodyStep[]
): { fetch: typeof globalThis.fetch; requests: () => number } => {
let calls = 0;
const fake = async (): Promise<Response> => {
const step = steps[calls++];
if (step === undefined) {
throw new Error(`scriptedCdnFetch: no step for request #${calls}`);
}
if (step.kind === "status") {
return new Response("error", { status: step.status });
}
if (step.kind === "body") {
return new Response(step.bytes, { status: 200 });
}
const bytes = step.bytes;
return new Response(
new ReadableStream<Uint8Array>({
start(controller) {
controller.enqueue(bytes);
controller.error(
errnoError("ECONNRESET", "aborted by peer"),
);
},
}),
{ status: 200 },
);
};
return { fetch: fake as typeof globalThis.fetch, requests: () => calls };
};
/**
* Build an EnteFile plus ApiClient whose file *and* thumbnail streams both
* serve `body` under `header`. The download path under test is otherwise
* identical for the two, so every truncation/atomicity case below runs
* against both entry points from a single fixture.
*
* The default policy here is a single attempt. The failure-contract tests are
* about what the caller and the filesystem are left with, not about how many
* times quak asked; pinning attempts to one keeps them saying exactly that,
* and keeps them from re-decrypting a 4 MiB fixture four times over. The
* retry counts have their own tests at the bottom of this file, which set the
* attempt count explicitly.
*/
const fixtureFor = (
key: Uint8Array,
header: Uint8Array,
body: Uint8Array,
retry: RetryOptions = { ...noWait, attempts: 1 },
): { api: ApiClient; file: EnteFile } => ({
api: new ApiClient({ fetch: mockFetchForBody(body), retry }),
file: buildMockEnteFile(key, header, header),
});
// The two entry points share `streamDecrypt` and the atomic-write wrapper,
// so the contract tests are written once and run against both.
const entryPoints = [
{ name: "downloadFile", download: downloadFile },
{ name: "downloadThumbnail", download: downloadThumbnail },
];
// With no `outPath`, the destination is named after `metadata.title`, relative
// to the working directory. Such tests run inside a temporary directory:
// `make check` must not create files in the repo root.
const inDirectory = async <T>(
dir: string,
run: () => Promise<T>,
): Promise<T> => {
const previous = process.cwd();
process.chdir(dir);
try {
return await run();
} finally {
process.chdir(previous);
}
};
// ---------------------------------------------------------------------------
// Tests
// ---------------------------------------------------------------------------
describe("downloadFile", () => {
it("downloads, decrypts, and writes a single-chunk file", async () => {
const plaintext = new TextEncoder().encode(
"Hello from quak! This is a test photo payload.",
);
const key = sodium.crypto_secretstream_xchacha20poly1305_keygen();
const { header, ciphertext } = encryptFileBody(plaintext, key);
// Separate header for thumbnail (not used in this test path but
// needed to construct the EnteFile)
const thumbPush =
sodium.crypto_secretstream_xchacha20poly1305_init_push(key);
const file = buildMockEnteFile(key, header, thumbPush.header);
const api = new ApiClient({ fetch: mockFetchForBody(ciphertext) });
const outPath = join(testDir, "single-chunk.jpg");
const result = await downloadFile(api, file, outPath);
// The whole DownloadResult shape is asserted, not just its fields:
// callers depend on `path` being the destination they asked for
// (never the temporary file used along the way) and on
// `bytesWritten` being the plaintext length.
expect(result).toEqual({
path: outPath,
bytesWritten: plaintext.length,
});
expect(readFileSync(outPath)).toEqual(Buffer.from(plaintext));
});
it("uses metadata.title as filename when outPath is omitted", async () => {
const plaintext = new Uint8Array([1, 2, 3]);
const key = sodium.crypto_secretstream_xchacha20poly1305_keygen();
const { header, ciphertext } = encryptFileBody(plaintext, key);
const thumbPush =
sodium.crypto_secretstream_xchacha20poly1305_init_push(key);
const file = buildMockEnteFile(key, header, thumbPush.header);
file.metadata.title = "fallback-name.png";
const dir = mkdtempSync(join(testDir, "title-"));
const api = new ApiClient({ fetch: mockFetchForBody(ciphertext) });
const result = await inDirectory(dir, () => downloadFile(api, file));
expect(result.path).toBe("fallback-name.png");
expect(readFileSync(join(dir, "fallback-name.png"))).toEqual(
Buffer.from(plaintext),
);
});
it("keeps a hostile title inside the working directory", async () => {
// The server controls the title. `../escaped.png` must not write to
// the parent directory; it becomes one file name in the current one.
const { api, file } = fixtureFor(
multiChunkKey,
multiChunk.header,
multiChunk.body,
);
file.metadata.title = "../escaped.png";
const parent = mkdtempSync(join(testDir, "hostile-"));
const dir = join(parent, "cwd");
mkdirSync(dir);
const result = await inDirectory(dir, () => downloadFile(api, file));
expect(result.path).toBe("__escaped.png");
expect(readdirSync(dir)).toEqual(["__escaped.png"]);
expect(readdirSync(parent)).toEqual(["cwd"]);
});
it("uses an explicit outPath verbatim, even one with ..", async () => {
// The caller is trusted: its path is not sanitized.
const { api, file } = fixtureFor(
multiChunkKey,
multiChunk.header,
multiChunk.body,
);
const dir = mkdtempSync(join(testDir, "explicit-"));
mkdirSync(join(dir, "sub"));
const outPath = join(dir, "sub", "..", "explicit.bin");
const result = await downloadFile(api, file, outPath);
expect(result.path).toBe(outPath);
expect(existsSync(join(dir, "explicit.bin"))).toBe(true);
});
it("handles a larger single-chunk file (random binary payload)", async () => {
// Most photos are under 4 MiB and therefore a single secretstream
// chunk. This test exercises a non-trivial payload size with
// arbitrary binary data (not just ASCII) to verify no encoding bugs.
const plaintext = patternBytes(100_000, 11);
const key = sodium.crypto_secretstream_xchacha20poly1305_keygen();
const { header, ciphertext } = encryptFileBody(plaintext, key);
const thumbPush =
sodium.crypto_secretstream_xchacha20poly1305_init_push(key);
const file = buildMockEnteFile(key, header, thumbPush.header);
const api = new ApiClient({ fetch: mockFetchForBody(ciphertext) });
const outPath = join(testDir, "large-single.bin");
const result = await downloadFile(api, file, outPath);
expect(result.bytesWritten).toBe(100_000);
expectSameBytes(readFileSync(outPath), plaintext);
});
it("decrypts a body that spans several secretstream chunks", async () => {
// Files over 4 MiB arrive as several ciphertext chunks concatenated
// into one HTTP body. The downloader has to re-split them on the
// exact chunk boundary; getting that wrong corrupts every large
// photo in an account. This is also the positive control for the
// truncation tests below: it proves the multi-chunk fixture itself
// decrypts cleanly when nothing has been removed from it.
const { api, file } = fixtureFor(
multiChunkKey,
multiChunk.header,
multiChunk.body,
);
const outPath = join(testDir, "multi-chunk.bin");
const result = await downloadFile(api, file, outPath);
expect(result.bytesWritten).toBe(multiChunk.plaintext.length);
expectSameBytes(readFileSync(outPath), multiChunk.plaintext);
});
});
describe("downloadThumbnail", () => {
it("downloads and decrypts the thumbnail stream", async () => {
const plaintext = new Uint8Array([0xff, 0xd8, 0xff, 0xe0]); // JPEG SOI
const key = sodium.crypto_secretstream_xchacha20poly1305_keygen();
const filePush =
sodium.crypto_secretstream_xchacha20poly1305_init_push(key);
const { header: thumbHeader, ciphertext: thumbCipher } =
encryptFileBody(plaintext, key);
const file = buildMockEnteFile(key, filePush.header, thumbHeader);
const api = new ApiClient({ fetch: mockFetchForBody(thumbCipher) });
const outPath = join(testDir, "thumb.jpg");
const result = await downloadThumbnail(api, file, outPath);
expect(result).toEqual({ path: outPath, bytesWritten: 4 });
expect(readFileSync(outPath)).toEqual(Buffer.from(plaintext));
});
it("names the thumbnail thumb_ plus the sanitized title", async () => {
const { api, file } = fixtureFor(
multiChunkKey,
multiChunk.header,
multiChunk.body,
);
file.metadata.title = "/etc/passwd";
const dir = mkdtempSync(join(testDir, "thumb-title-"));
const result = await inDirectory(dir, () =>
downloadThumbnail(api, file),
);
expect(result.path).toBe("thumb__etc_passwd");
expect(readdirSync(dir)).toEqual(["thumb__etc_passwd"]);
});
});
// ---------------------------------------------------------------------------
// Truncation detection and atomic writes
//
// Everything below is the failure contract. It is deliberately written once
// per entry point via `entryPoints`, because `downloadFile` and
// `downloadThumbnail` must behave identically here: a corrupt thumbnail is
// just as unacceptable as a corrupt original, and `runBackup` trusts both.
// ---------------------------------------------------------------------------
describe.each(entryPoints)(
"$name truncation handling",
({ name, download }) => {
/** A fresh, empty directory so leftover-file assertions are meaningful. */
const freshDir = (): string => {
const dir = mkdtempSync(join(testDir, `${name}-`));
return dir;
};
it("rejects a body whose final TAG_FINAL chunk never arrived", async () => {
// Simulate a connection that dropped after the first 4 MiB chunk.
// Every byte that did arrive decrypts and authenticates perfectly —
// that is precisely the danger. The only signal that the file is
// incomplete is the absence of a chunk tagged TAG_FINAL, so the
// downloader must treat "stream ended on TAG_MESSAGE" as a hard
// error rather than returning a short file.
const truncatedBody = multiChunk.body.slice(
0,
multiChunk.finalChunkOffset,
);
const { api, file } = fixtureFor(
multiChunkKey,
multiChunk.header,
truncatedBody,
);
const outPath = join(freshDir(), "truncated.bin");
const err: unknown = await download(api, file, outPath).catch(
(e: unknown) => e,
);
// The type, not the wording, is the contract. The retry policy
// classifies truncation as worth another attempt, and it decides
// that with `instanceof`: matching on message text would make
// rewording a diagnostic silently turn every truncated download
// into a permanent failure.
expect(err).toBeInstanceOf(TruncatedStreamError);
expect((err as Error).message).toMatch(/truncated/i);
});
it("rejects a body whose final chunk arrived only in part", async () => {
// The likelier shape of a dropped connection: the transfer stops
// in the middle of a chunk rather than neatly between two. The
// bytes that arrived are a prefix of a complete chunk, so Poly1305
// rejects them — which is, cryptographically, indistinguishable
// from corruption of a whole chunk.
//
// It is still reported as truncation, because that is what it
// almost always is and because this library's entire reason for
// checking TAG_FINAL is to make a short transfer visible. Calling
// a short transfer "authentication failed" would send a user
// hunting for a corrupt file when their network is at fault. The
// underlying authentication failure is kept as the error's
// `cause`, so the real diagnosis is never lost.
const shortBody = multiChunk.body.slice(
0,
multiChunk.body.length - 8,
);
const { api, file } = fixtureFor(
multiChunkKey,
multiChunk.header,
shortBody,
);
const dir = freshDir();
const outPath = join(dir, "partial-final.bin");
const err = await download(api, file, outPath).catch(
(e: unknown) => e,
);
expect(err).toBeInstanceOf(TruncatedStreamError);
expect((err as Error).message).toMatch(/truncated/i);
expect((err as Error).cause).toBeInstanceOf(Error);
expect(((err as Error).cause as Error).message).toMatch(
/authentication failed/i,
);
// And, as with every other failure, the destination is untouched
// and no staged temp file survives.
expect(existsSync(outPath)).toBe(false);
expect(readdirSync(dir)).toEqual([]);
});
it("rejects an empty body instead of writing a zero-byte file", async () => {
// Ente always emits at least one chunk, even for empty content:
// `encryptBlob` shows that a zero-length plaintext still produces a
// TAG_FINAL chunk. A body with no chunks at all therefore means the
// transfer failed, not that the file is empty. Writing a zero-byte
// file here would be the worst outcome, because `runBackup` would
// then see a file it considers present and never retry it.
const { api, file } = fixtureFor(
multiChunkKey,
multiChunk.header,
new Uint8Array(0),
);
const outPath = join(freshDir(), "empty.bin");
await expect(download(api, file, outPath)).rejects.toBeInstanceOf(
TruncatedStreamError,
);
});
it("leaves no file at the destination after a truncated download", async () => {
// The caller's contract: if the promise rejects, the destination
// path does not exist. Nothing downstream should ever have to guess
// whether a leftover file is complete.
//
// The body here is a single chunk that was never tagged TAG_FINAL,
// which puts the downloader in exactly the terminal state a lost
// last chunk produces, without the cost of a 4 MiB fixture. What
// this test is really about is the state of the filesystem after
// the rejection.
const key = sodium.crypto_secretstream_xchacha20poly1305_keygen();
const { header, ciphertext } = encryptNonFinalBody(
patternBytes(256, 21),
key,
);
const { api, file } = fixtureFor(key, header, ciphertext);
const dir = freshDir();
const outPath = join(dir, "absent.bin");
await expect(download(api, file, outPath)).rejects.toBeInstanceOf(
TruncatedStreamError,
);
expect(existsSync(outPath)).toBe(false);
// And no temporary scratch file is left behind either: the download
// stages plaintext in a sibling temp file, which must be removed on
// the failure path so repeated failures cannot fill the disk.
expect(readdirSync(dir)).toEqual([]);
});
it("reports a corrupt whole chunk as an authentication failure, not truncation", async () => {
// The counterpart to the partial-final-chunk case above, and the
// reason the two are distinguishable at all. A byte is flipped
// inside the first chunk of a multi-chunk body: that chunk arrives
// complete — the stream goes on past it — so its failure cannot be
// a short transfer. It is corruption, and the caller is told so,
// with `pullStreamChunk`'s error propagated unchanged because it is
// the real diagnosis.
//
// The same on-disk guarantee holds for this failure mode as for
// every other: nothing at the destination, nothing left over.
const corrupted = Uint8Array.from(multiChunk.body);
corrupted[10] ^= 0xff;
const { api, file } = fixtureFor(
multiChunkKey,
multiChunk.header,
corrupted,
);
const dir = freshDir();
const outPath = join(dir, "corrupt.bin");
const err: unknown = await download(api, file, outPath).catch(
(e: unknown) => e,
);
expect(err).toBeInstanceOf(Error);
expect((err as Error).message).toMatch(/authentication failed/i);
// And explicitly *not* the truncation type, because that type is
// what the retry policy keys on: mislabelling corruption as
// truncation would spend the whole attempt budget re-downloading
// a file that will never decrypt.
expect(err).not.toBeInstanceOf(TruncatedStreamError);
expect(existsSync(outPath)).toBe(false);
expect(readdirSync(dir)).toEqual([]);
});
it("does not clobber an existing file when the download fails", async () => {
// The repair case. A user re-running a backup over a directory that
// already holds good originals must never end up worse off: a failed
// download leaves the previous contents exactly as they were, so the
// old good copy survives until a complete new one is available to
// replace it in a single rename.
const existing = new TextEncoder().encode(
"previously downloaded, known-good contents",
);
const key = sodium.crypto_secretstream_xchacha20poly1305_keygen();
const { header, ciphertext } = encryptNonFinalBody(
patternBytes(256, 22),
key,
);
const { api, file } = fixtureFor(key, header, ciphertext);
const dir = freshDir();
const outPath = join(dir, "existing.bin");
writeFileSync(outPath, existing);
await expect(download(api, file, outPath)).rejects.toBeInstanceOf(
TruncatedStreamError,
);
expect(readFileSync(outPath)).toEqual(Buffer.from(existing));
expect(readdirSync(dir)).toEqual(["existing.bin"]);
});
it("replaces an existing file when the download succeeds", async () => {
// The mirror image of the previous test: a complete download does
// overwrite whatever was at the destination, atomically, via rename.
const existing = new TextEncoder().encode("stale contents");
const plaintext = patternBytes(512, 23);
const key = sodium.crypto_secretstream_xchacha20poly1305_keygen();
const { header, ciphertext } = encryptFileBody(plaintext, key);
const { api, file } = fixtureFor(key, header, ciphertext);
const dir = freshDir();
const outPath = join(dir, "replaced.bin");
writeFileSync(outPath, existing);
const result = await download(api, file, outPath);
expect(result).toEqual({ path: outPath, bytesWritten: 512 });
expect(readFileSync(outPath)).toEqual(Buffer.from(plaintext));
// The temp file is gone once the rename has happened, so a
// successful download leaves exactly one file behind.
expect(readdirSync(dir)).toEqual(["replaced.bin"]);
});
it("stages the plaintext in a sibling temp file and renames it into place", async () => {
// The atomic write, observed directly rather than inferred from an
// empty directory. Every other failure in this file is injected
// inside `streamDecrypt`, which runs before anything is written —
// so under those tests a plain `writeFile` to the destination would
// look identical. This one watches the rename itself.
//
// Two properties are load-bearing. The staging file must exist on
// disk when the rename happens: that is what makes the destination
// appear complete or not at all, instead of filling up as bytes
// land. And it must be a sibling of the destination, because
// `rename` is only atomic within one filesystem — staging in
// `/tmp` and renaming across a mount point would silently become a
// copy, reintroducing the partial-file window this exists to close.
const plaintext = patternBytes(512, 31);
const key = sodium.crypto_secretstream_xchacha20poly1305_keygen();
const { header, ciphertext } = encryptFileBody(plaintext, key);
const { api, file } = fixtureFor(key, header, ciphertext);
const dir = freshDir();
const outPath = join(dir, "staged.bin");
await download(api, file, outPath);
expect(renameHook.calls).toHaveLength(1);
const staged = renameHook.calls[0]!;
expect(staged.to).toBe(outPath);
expect(staged.from).not.toBe(outPath);
expect(dirname(staged.from)).toBe(dir);
expect(staged.sourceExisted).toBe(true);
// Afterwards the temp file is gone and only the destination is
// left, holding the complete plaintext.
expect(existsSync(staged.from)).toBe(false);
expect(readFileSync(outPath)).toEqual(Buffer.from(plaintext));
expect(readdirSync(dir)).toEqual(["staged.bin"]);
});
it("removes the staged temp file when the rename itself fails", async () => {
// The cleanup path. It can only run when something fails at or
// after the write, which no amount of bad network data can
// produce: by the time anything is written the whole stream has
// already decrypted and verified. Failing the rename is what
// reaches it — a real possibility on a full disk, a read-only
// mount, or a destination that has become a directory.
//
// This is the only case in which the temp file is on disk at the
// moment of failure, so it is the only one that can show it is
// actually removed rather than merely never created. It also pins
// that the caller sees the original failure: a cleanup that threw
// over the top of it would hide why the download failed.
const existing = new TextEncoder().encode("known-good contents");
const plaintext = patternBytes(512, 32);
const key = sodium.crypto_secretstream_xchacha20poly1305_keygen();
const { header, ciphertext } = encryptFileBody(plaintext, key);
const { api, file } = fixtureFor(key, header, ciphertext);
const dir = freshDir();
const outPath = join(dir, "rename-fails.bin");
writeFileSync(outPath, existing);
renameHook.failWith = new Error("simulated rename failure");
await expect(download(api, file, outPath)).rejects.toThrow(
"simulated rename failure",
);
expect(renameHook.calls).toHaveLength(1);
const staged = renameHook.calls[0]!;
expect(staged.sourceExisted).toBe(true);
expect(existsSync(staged.from)).toBe(false);
// The previous contents are still there, untouched, and the
// directory holds nothing else.
expect(readFileSync(outPath)).toEqual(Buffer.from(existing));
expect(readdirSync(dir)).toEqual(["rename-fails.bin"]);
});
it("fails without creating anything when the destination directory does not exist", async () => {
const key = sodium.crypto_secretstream_xchacha20poly1305_keygen();
const { header, ciphertext } = encryptFileBody(
patternBytes(64, 33),
key,
);
const { api, file } = fixtureFor(key, header, ciphertext);
const dir = freshDir();
const outPath = join(dir, "missing", "never.bin");
await expect(download(api, file, outPath)).rejects.toMatchObject({
code: "ENOENT",
});
// The missing directory is not created on the caller's behalf.
expect(readdirSync(dir)).toEqual([]);
});
// Root ignores directory permissions, so this fails when run as root.
// The `test` phase of the `Dockerfile` runs as the `node` user.
it("fails without creating anything when the destination directory is not writable", async () => {
const key = sodium.crypto_secretstream_xchacha20poly1305_keygen();
const { header, ciphertext } = encryptFileBody(
patternBytes(64, 34),
key,
);
const { api, file } = fixtureFor(key, header, ciphertext);
const dir = freshDir();
const outPath = join(dir, "never.bin");
chmodSync(dir, 0o500);
try {
await expect(
download(api, file, outPath),
).rejects.toMatchObject({ code: "EACCES" });
} finally {
chmodSync(dir, 0o700);
}
expect(readdirSync(dir)).toEqual([]);
});
},
);
// ---------------------------------------------------------------------------
// Retries
//
// What is retried here is the whole download — request, stream consumption,
// decryption — because only the first of those three happens inside
// `ApiClient`. Every assertion counts requests; none of them measures time.
// ---------------------------------------------------------------------------
describe.each(entryPoints)("$name retries", ({ name, download }) => {
const freshDir = (): string => mkdtempSync(join(testDir, `${name}-retry-`));
/** A cheap single-chunk fixture: no 4 MiB encryption in the retry tests. */
const smallFixture = (
seed: number,
): {
key: Uint8Array;
header: Uint8Array;
ciphertext: Uint8Array;
plaintext: Uint8Array;
} => {
const plaintext = patternBytes(1024, seed);
const key = sodium.crypto_secretstream_xchacha20poly1305_keygen();
const { header, ciphertext } = encryptFileBody(plaintext, key);
return { key, header, ciphertext, plaintext };
};
const clientFor = (
fetch: typeof globalThis.fetch,
attempts: number,
): ApiClient => new ApiClient({ fetch, retry: { ...noWait, attempts } });
it("retries a connection reset that happened mid-body", async () => {
// The case `ApiClient` cannot see. Its own request succeeded: headers
// arrived, a `ReadableStream` was handed back, and only then did the
// socket die. Retrying the fetch alone would have caught nothing,
// which is why the retry wraps the whole sequence.
const { key, header, ciphertext, plaintext } = smallFixture(41);
const { fetch, requests } = scriptedCdnFetch(
{ kind: "reset", bytes: ciphertext.slice(0, 16) },
{ kind: "body", bytes: ciphertext },
);
const api = clientFor(fetch, 4);
const file = buildMockEnteFile(key, header, header);
const dir = freshDir();
const outPath = join(dir, "reset-then-ok.bin");
const result = await download(api, file, outPath);
expect(requests()).toBe(2);
expect(result.bytesWritten).toBe(plaintext.length);
expectSameBytes(readFileSync(outPath), plaintext);
});
it("stages one temp file for the attempt that succeeded, not one per attempt", async () => {
// Each streaming attempt stages into its own temp file, but a retried
// download must not leave a trail of half-written scratch files: a
// failed attempt removes its temp file, and the destination is renamed
// into place exactly once — by the attempt that produced a complete,
// authenticated plaintext. (Here the two failed attempts reset before a
// whole chunk is pulled, so they write nothing; the point stands either
// way — see the retry-restart test below, where they do write.)
const { key, header, ciphertext } = smallFixture(42);
const { fetch } = scriptedCdnFetch(
{ kind: "reset", bytes: ciphertext.slice(0, 16) },
{ kind: "reset", bytes: ciphertext.slice(0, 16) },
{ kind: "body", bytes: ciphertext },
);
const api = clientFor(fetch, 4);
const file = buildMockEnteFile(key, header, header);
const dir = freshDir();
const outPath = join(dir, "one-stage.bin");
await download(api, file, outPath);
expect(renameHook.calls).toHaveLength(1);
expect(renameHook.calls[0]!.to).toBe(outPath);
expect(readdirSync(dir)).toEqual(["one-stage.bin"]);
});
it("retries a truncated body and gives up after the configured attempts", async () => {
// Truncation is retryable — the file on the server is intact, the
// transfer was not — but it is not retryable forever. Three attempts
// configured, three requests, then the caller gets the error.
const key = sodium.crypto_secretstream_xchacha20poly1305_keygen();
const { header, ciphertext } = encryptNonFinalBody(
patternBytes(256, 43),
key,
);
const { fetch, requests } = scriptedCdnFetch(
{ kind: "body", bytes: ciphertext },
{ kind: "body", bytes: ciphertext },
{ kind: "body", bytes: ciphertext },
{ kind: "body", bytes: ciphertext },
);
const api = clientFor(fetch, 3);
const file = buildMockEnteFile(key, header, header);
const dir = freshDir();
const outPath = join(dir, "always-truncated.bin");
await expect(download(api, file, outPath)).rejects.toBeInstanceOf(
TruncatedStreamError,
);
expect(requests()).toBe(3);
// Every attempt failed before anything was written, so the directory
// is still empty.
expect(readdirSync(dir)).toEqual([]);
});
it("issues exactly one request when the file is gone", async () => {
// A 404 from the CDN is an answer. `runBackup` logs it and moves on;
// spending three more requests and three backoff waits on it would
// slow a large backup down for nothing.
const { key, header } = smallFixture(44);
const { fetch, requests } = scriptedCdnFetch(
{ kind: "status", status: 404 },
{ kind: "status", status: 404 },
{ kind: "status", status: 404 },
{ kind: "status", status: 404 },
);
const api = clientFor(fetch, 4);
const file = buildMockEnteFile(key, header, header);
const outPath = join(freshDir(), "gone.bin");
const err: unknown = await download(api, file, outPath).catch(
(e: unknown) => e,
);
expect(err).toBeInstanceOf(ApiError);
expect((err as ApiError).status).toBe(404);
expect(requests()).toBe(1);
});
it("retries a 503 from the CDN", async () => {
const { key, header, ciphertext, plaintext } = smallFixture(45);
const { fetch, requests } = scriptedCdnFetch(
{ kind: "status", status: 503 },
{ kind: "status", status: 503 },
{ kind: "body", bytes: ciphertext },
);
const api = clientFor(fetch, 4);
const file = buildMockEnteFile(key, header, header);
const outPath = join(freshDir(), "flaky-cdn.bin");
await download(api, file, outPath);
expect(requests()).toBe(3);
expectSameBytes(readFileSync(outPath), plaintext);
});
it("spends one attempt budget, not one per layer", async () => {
// `ApiClient.getFileStream` retries on its own for direct callers.
// The download layer opts out of that and runs its own retry over the
// whole sequence. If it did not, the two budgets would compose: three
// attempts here would become nine requests to the CDN for a single
// file, and the default four would become sixteen.
const { key, header } = smallFixture(46);
const steps: BodyStep[] = Array.from({ length: 12 }, () => ({
kind: "status" as const,
status: 503,
}));
const { fetch, requests } = scriptedCdnFetch(...steps);
const api = clientFor(fetch, 3);
const file = buildMockEnteFile(key, header, header);
const outPath = join(freshDir(), "budget.bin");
await expect(download(api, file, outPath)).rejects.toBeInstanceOf(
ApiError,
);
expect(requests()).toBe(3);
});
});
// ---------------------------------------------------------------------------
// Streaming decrypt to disk
//
// The plaintext is never held whole in memory: each secretstream chunk is
// written to the temp file as it is decrypted, so peak memory is bounded by the
// chunk size rather than the file size. These tests watch the writes directly
// (see `writeHook`) rather than infer memory behaviour from the final file.
// ---------------------------------------------------------------------------
describe.each(entryPoints)("$name streams to disk", ({ name, download }) => {
const freshDir = (): string =>
mkdtempSync(join(testDir, `${name}-stream-`));
/** Writes recorded against staged temp files (not the `writeFile` path). */
const tempWrites = (): { path: string; length: number }[] =>
writeHook.writes.filter((w) => w.path.endsWith(".tmp"));
it("writes one chunk at a time, none larger than STREAM_CHUNK_SIZE", async () => {
// The multi-chunk fixture decrypts to one full 4 MiB chunk plus a small
// final chunk. A streaming writer therefore issues exactly two writes,
// of STREAM_CHUNK_SIZE and then the final chunk's length — never a
// single write carrying the whole 4 MiB + 1 KiB file. That per-chunk
// shape is what "memory bounded by chunk size" means in practice: the
// plaintext is handed to the filesystem and dropped, chunk by chunk.
const { api, file } = fixtureFor(
multiChunkKey,
multiChunk.header,
multiChunk.body,
);
const outPath = join(freshDir(), "streamed.bin");
const result = await download(api, file, outPath);
const writes = tempWrites();
expect(writes.map((w) => w.length)).toEqual([
STREAM_CHUNK_SIZE,
multiChunk.plaintext.length - STREAM_CHUNK_SIZE,
]);
// No single write ever carried the whole file, and every write fits in
// one chunk's worth of memory.
for (const w of writes) {
expect(w.length).toBeLessThanOrEqual(STREAM_CHUNK_SIZE);
}
expect(result.bytesWritten).toBe(multiChunk.plaintext.length);
expectSameBytes(readFileSync(outPath), multiChunk.plaintext);
});
it("restarts from byte zero on a retry, replacing the temp file cleanly", async () => {
// The secretstream pull state is not resumable, so a retry cannot
// continue a half-written file — it must start over. The first attempt
// here delivers a complete leading chunk and then stops before the
// TAG_FINAL chunk: 4 MiB of plaintext lands in a temp file, then the
// download is rejected as truncated and that temp file is discarded.
// The retry streams the whole body into a *fresh* temp file, so the
// destination ends up with exactly the plaintext once — never the
// leading chunk twice, and never a stale temp file left behind.
const truncatedBody = multiChunk.body.slice(
0,
multiChunk.finalChunkOffset,
);
const { fetch, requests } = scriptedCdnFetch(
{ kind: "body", bytes: truncatedBody },
{ kind: "body", bytes: multiChunk.body },
);
const api = new ApiClient({
fetch,
retry: { ...noWait, attempts: 4 },
});
const file = buildMockEnteFile(
multiChunkKey,
multiChunk.header,
multiChunk.header,
);
const dir = freshDir();
const outPath = join(dir, "retry-restart.bin");
const result = await download(api, file, outPath);
expect(requests()).toBe(2);
// Both attempts streamed to disk, each into its own temp file: the
// truncated first attempt wrote before it failed, proving the retry did
// not resume a partial file but replaced it.
const distinctTemps = new Set(tempWrites().map((w) => w.path));
expect(distinctTemps.size).toBe(2);
// The destination holds the complete plaintext exactly once, and no
// temp file survives.
expect(result.bytesWritten).toBe(multiChunk.plaintext.length);
expectSameBytes(readFileSync(outPath), multiChunk.plaintext);
expect(renameHook.calls).toHaveLength(1);
expect(readdirSync(dir)).toEqual(["retry-restart.bin"]);
});
});
describe("download retries: corruption is not retried", () => {
it("gives up immediately on a chunk that failed to authenticate", async () => {
// A whole chunk that failed to authenticate while the stream
// continued past it is corruption or a wrong key. Neither is fixed by
// asking again, and a backup run that retried every such file would
// multiply the cost of a genuinely broken file by the attempt count.
//
// This is also the boundary of the single-chunk ambiguity documented
// at the classifier: the split is only achievable because this body
// has more than one chunk.
const corrupted = Uint8Array.from(multiChunk.body);
corrupted[10] ^= 0xff;
const { fetch, requests } = scriptedCdnFetch(
{ kind: "body", bytes: corrupted },
{ kind: "body", bytes: corrupted },
{ kind: "body", bytes: corrupted },
{ kind: "body", bytes: corrupted },
);
const api = new ApiClient({ fetch, retry: { ...noWait, attempts: 4 } });
const file = buildMockEnteFile(
multiChunkKey,
multiChunk.header,
multiChunk.header,
);
const outPath = join(mkdtempSync(join(testDir, "corrupt-")), "c.bin");
await expect(downloadFile(api, file, outPath)).rejects.toThrow(
/authentication failed/i,
);
expect(requests()).toBe(1);
});
it("cancels the response body when decryption fails", async () => {
// A backup run carries on past a failed file, so a body left open on
// failure would hold its connection until garbage collection, once
// per failed file. This body delivers a corrupt chunk and then stays
// open, so only a cancel from the downloader can close it.
const corrupted = Uint8Array.from(multiChunk.body);
corrupted[10] ^= 0xff;
let cancelled = false;
const fetch = (async () =>
new Response(
new ReadableStream<Uint8Array>({
start(controller) {
controller.enqueue(corrupted);
},
cancel() {
cancelled = true;
},
}),
{ status: 200 },
)) as typeof globalThis.fetch;
const api = new ApiClient({ fetch, retry: { ...noWait, attempts: 1 } });
const file = buildMockEnteFile(
multiChunkKey,
multiChunk.header,
multiChunk.header,
);
const outPath = join(mkdtempSync(join(testDir, "cancel-")), "c.bin");
await expect(downloadFile(api, file, outPath)).rejects.toThrow(
/authentication failed/i,
);
expect(cancelled).toBe(true);
});
it("cancels the response body when the temp file cannot be opened", async () => {
// The download fails before a byte of the body is read, so the body
// is still open and only a cancel from the downloader can close it.
let cancelled = false;
const fetch = (async () =>
new Response(
new ReadableStream<Uint8Array>({
start(controller) {
controller.enqueue(multiChunk.body);
},
cancel() {
cancelled = true;
},
}),
{ status: 200 },
)) as typeof globalThis.fetch;
const api = new ApiClient({ fetch, retry: { ...noWait, attempts: 1 } });
const file = buildMockEnteFile(
multiChunkKey,
multiChunk.header,
multiChunk.header,
);
const outPath = join(
mkdtempSync(join(testDir, "cancel-")),
"missing",
"c.bin",
);
await expect(downloadFile(api, file, outPath)).rejects.toMatchObject({
code: "ENOENT",
});
expect(cancelled).toBe(true);
});
it("cancels the response body when the header is malformed", async () => {
// The header is rejected before the body is read, so the body is
// still open and only a cancel from the downloader can close it.
let cancelled = false;
const fetch = (async () =>
new Response(
new ReadableStream<Uint8Array>({
start(controller) {
controller.enqueue(multiChunk.body);
},
cancel() {
cancelled = true;
},
}),
{ status: 200 },
)) as typeof globalThis.fetch;
const api = new ApiClient({ fetch, retry: { ...noWait, attempts: 1 } });
const shortHeader = multiChunk.header.subarray(0, 5);
const file = buildMockEnteFile(multiChunkKey, shortHeader, shortHeader);
const outPath = join(mkdtempSync(join(testDir, "cancel-")), "c.bin");
await expect(downloadFile(api, file, outPath)).rejects.toThrow();
expect(cancelled).toBe(true);
});
});
// ---------------------------------------------------------------------------
// Fragmented network reads
//
// A CDN does not hand the body over one secretstream chunk at a time; it
// arrives in whatever pieces the socket produces, many of them far smaller than
// a chunk and most straddling a chunk boundary. `streamDecrypt` reassembles
// those pieces before decrypting, copying each received byte once rather than
// recopying the whole accumulator on every read. This is the path the other
// fixtures never take — their mock fetch delivers each body as a single
// `Response` value, i.e. one read — so it is exercised explicitly here.
// ---------------------------------------------------------------------------
/**
* A fetch that serves `body` through a `ReadableStream` sliced into many
* fixed-size pieces, imitating a socket that trickles bytes in. `pieceSize` is
* chosen not to divide the chunk framing evenly, so pieces straddle the
* `ENC_CHUNK_SIZE` boundary the downloader splits on — the case a single-value
* body can never produce. `emitted` reports how many pieces were yielded, so a
* test can assert the body really was fragmented and not delivered whole.
*/
const mockFetchForFragmentedBody = (
body: Uint8Array,
pieceSize: number,
): { fetch: typeof globalThis.fetch; emitted: () => number } => {
let pieces = 0;
const fake = async (): Promise<Response> =>
new Response(
new ReadableStream<Uint8Array>({
start(controller) {
for (let off = 0; off < body.length; off += pieceSize) {
controller.enqueue(body.subarray(off, off + pieceSize));
pieces++;
}
controller.close();
},
}),
{ status: 200 },
);
return { fetch: fake as typeof globalThis.fetch, emitted: () => pieces };
};
describe("streamDecrypt fragmented reads", () => {
it("decrypts a multi-chunk body delivered in many small pieces", async () => {
// The multi-chunk fixture (one full 4 MiB chunk plus a small final
// chunk) delivered in 1000-byte pieces: several thousand reads, with
// the piece that spans the 4 MiB + 17 byte chunk boundary split across
// two chunks by the reassembler. The plaintext must come out
// byte-identical to the single-read case, and the chunk framing must be
// untouched: exactly two writes, `STREAM_CHUNK_SIZE` then the final
// chunk, the same as when the body arrives whole. If the boundary
// handling were off by a byte under fragmentation, either the pull
// would fail to authenticate or the write sizes would shift.
const { fetch, emitted } = mockFetchForFragmentedBody(
multiChunk.body,
1000,
);
const api = new ApiClient({ fetch });
const file = buildMockEnteFile(
multiChunkKey,
multiChunk.header,
multiChunk.header,
);
const dir = mkdtempSync(join(testDir, "fragmented-"));
const outPath = join(dir, "fragmented.bin");
const result = await downloadFile(api, file, outPath);
// The body really was trickled in, not handed over whole.
expect(emitted()).toBeGreaterThan(1000);
const writes = writeHook.writes.filter((w) => w.path.endsWith(".tmp"));
expect(writes.map((w) => w.length)).toEqual([
STREAM_CHUNK_SIZE,
multiChunk.plaintext.length - STREAM_CHUNK_SIZE,
]);
expect(result.bytesWritten).toBe(multiChunk.plaintext.length);
expectSameBytes(readFileSync(outPath), multiChunk.plaintext);
});
});
// ---------------------------------------------------------------------------
// Durable atomic writes
//
// `writeAtomic` is exported so the metadata store can reuse the same
// power-cut-safe write. Its durability is the point: the bytes and the new
// directory entry must both be on stable storage before it returns, so a crash
// immediately afterwards cannot resurrect an empty renamed file (#22 area 1).
// ---------------------------------------------------------------------------
describe("writeAtomic", () => {
it("fsyncs the temp file before the rename and the directory after", async () => {
const dir = mkdtempSync(join(testDir, "atomic-"));
const dest = join(dir, "durable.bin");
const bytes = patternBytes(2048, 71);
await writeAtomic(dest, bytes);
expect(readFileSync(dest)).toEqual(Buffer.from(bytes));
// The order is the durability contract: fsync the staged temp file so
// its contents are on disk, rename it into place, then fsync the
// directory so that new entry is on disk too. Do the directory fsync
// before the rename, or skip it, and a crash can lose the rename.
expect(durabilityHook.events).toHaveLength(3);
expect(durabilityHook.events[0]).toMatch(/^sync:w:.*\.tmp$/);
expect(durabilityHook.events[1]).toBe(`rename:${dest}`);
expect(durabilityHook.events[2]).toBe(`sync:r:${dir}`);
});
it("leaves no temp file behind when the write cannot be renamed", async () => {
const dir = mkdtempSync(join(testDir, "atomic-fail-"));
const dest = join(dir, "unrenamable.bin");
renameHook.failWith = new Error("simulated rename failure");
await expect(writeAtomic(dest, patternBytes(64, 72))).rejects.toThrow(
"simulated rename failure",
);
// The staged temp file was fsynced, then the rename failed; the cleanup
// path must remove it so a repeatedly failing write cannot fill the disk.
expect(existsSync(dest)).toBe(false);
expect(readdirSync(dir)).toEqual([]);
});
});
// ---------------------------------------------------------------------------
// Per-chunk progress
//
// Callers streaming a large file want bytes-written as it lands, not only the
// final total. The hook fires as decrypted plaintext accumulates; its values
// are non-decreasing and its last value is exactly `bytesWritten`.
// ---------------------------------------------------------------------------
describe.each(entryPoints)("$name progress", ({ name, download }) => {
it("reports monotonic progress ending at bytesWritten", async () => {
// The multi-chunk fixture pulls one full 4 MiB chunk and then a small
// final chunk, so the callback fires more than once and monotonicity is
// actually observable rather than trivially true for a single fire.
const { api, file } = fixtureFor(
multiChunkKey,
multiChunk.header,
multiChunk.body,
);
const outPath = join(
mkdtempSync(join(testDir, `${name}-progress-`)),
"p.bin",
);
const seen: number[] = [];
const result = await download(api, file, outPath, (bytesDone) => {
seen.push(bytesDone);
});
expect(seen.length).toBeGreaterThan(1);
for (let i = 1; i < seen.length; i++) {
expect(seen[i]!).toBeGreaterThan(seen[i - 1]!);
}
expect(seen[seen.length - 1]).toBe(result.bytesWritten);
expect(result.bytesWritten).toBe(multiChunk.plaintext.length);
});
it("downloads normally when no progress callback is given", async () => {
// The callback is optional and its absence must be side-effect-free:
// the download succeeds exactly as it does elsewhere in this file.
const plaintext = patternBytes(300, 73);
const key = sodium.crypto_secretstream_xchacha20poly1305_keygen();
const { header, ciphertext } = encryptFileBody(plaintext, key);
const { api, file } = fixtureFor(key, header, ciphertext);
const outPath = join(
mkdtempSync(join(testDir, `${name}-noprog-`)),
"n.bin",
);
const result = await download(api, file, outPath);
expect(result.bytesWritten).toBe(plaintext.length);
expectSameBytes(readFileSync(outPath), plaintext);
});
});
describe("downloadFile content hash", () => {
// Node's own BLAKE2b-512 is the reference, so these tests do not depend
// on the code under test to compute what they expect.
const blake2b = (bytes: Uint8Array): string =>
createHash("blake2b512").update(bytes).digest("base64");
// Serve `plaintext` encrypted as file 999 with the given metadata. Four
// responses are scripted so a retried mismatch would show in `requests`.
const setup = (plaintext: Uint8Array, metadata: Partial<FileMetadata>) => {
const key = sodium.crypto_secretstream_xchacha20poly1305_keygen();
const { header, ciphertext } = encryptFileBody(plaintext, key);
const file = buildMockEnteFile(key, header, header);
file.metadata = { ...file.metadata, ...metadata };
const body = { kind: "body", bytes: ciphertext } as const;
const { fetch, requests } = scriptedCdnFetch(body, body, body, body);
const api = new ApiClient({ fetch, retry: { ...noWait, attempts: 4 } });
const dir = mkdtempSync(join(testDir, "hash-"));
const outPath = join(dir, "f.bin");
return {
run: () => downloadFile(api, file, outPath),
dir,
outPath,
requests,
};
};
const livePhotoZip = zipSync({
"image.heic": patternBytes(500, 81),
"video.mov": patternBytes(900, 82),
});
const livePhotoHash = `${blake2b(patternBytes(500, 81))}:${blake2b(patternBytes(900, 82))}`;
it("stores a file whose hash matches", async () => {
const plaintext = patternBytes(700, 80);
const t = setup(plaintext, { hash: blake2b(plaintext) });
await t.run();
expectSameBytes(readFileSync(t.outPath), plaintext);
});
it("rejects a mismatch, stores nothing, names the file and does not retry", async () => {
const t = setup(patternBytes(700, 80), {
hash: blake2b(patternBytes(700, 79)),
});
await expect(t.run()).rejects.toThrow(
/file 999: content hash .* does not match/,
);
expect(readdirSync(t.dir)).toEqual([]);
expect(t.requests()).toBe(1);
});
it("stores a file with no recorded hash unchecked", async () => {
const plaintext = patternBytes(700, 80);
const t = setup(plaintext, { hash: undefined });
await t.run();
expectSameBytes(readFileSync(t.outPath), plaintext);
});
it("stores a live photo whose image and video hashes match", async () => {
const t = setup(livePhotoZip, {
fileType: "livePhoto",
hash: livePhotoHash,
});
await t.run();
expectSameBytes(readFileSync(t.outPath), livePhotoZip);
});
it("hashes a large live photo entry as it decompresses, never whole", async () => {
// 64 MiB of zeros deflates to a few kilobytes, the shape of a ZIP
// that would exhaust memory if expanded whole.
const image = new Uint8Array(64 * 1024 * 1024);
const video = patternBytes(900, 83);
const zip = zipSync({ "image.heic": image, "video.mov": video });
const t = setup(zip, {
fileType: "livePhoto",
hash: `${blake2b(image)}:${blake2b(video)}`,
});
await t.run();
expectSameBytes(readFileSync(t.outPath), zip);
const hashed = hashHook.lengths.reduce((a, b) => a + b, 0);
expect(hashed).toBe(image.length + video.length);
expect(Math.max(...hashHook.lengths)).toBeLessThanOrEqual(
2 * STREAM_CHUNK_SIZE,
);
});
it("rejects a live photo whose hash does not match", async () => {
// The whole ZIP's hash is not the recorded one: each part is hashed.
const t = setup(livePhotoZip, {
fileType: "livePhoto",
hash: blake2b(livePhotoZip),
});
await expect(t.run()).rejects.toThrow(
/file 999: content hash .* does not match/,
);
expect(readdirSync(t.dir)).toEqual([]);
});
it("rejects a live photo that is not a readable ZIP and does not retry", async () => {
// Bytes 8-9 of a ZIP entry's local header name its compression
// method; 99 is one no reader knows, so the entry cannot be read.
const zip = livePhotoZip.slice();
zip[8] = 99;
zip[9] = 0;
const t = setup(zip, { fileType: "livePhoto", hash: livePhotoHash });
await expect(t.run()).rejects.toThrow(
/file 999: live photo is not a readable ZIP/,
);
expect(readdirSync(t.dir)).toEqual([]);
expect(t.requests()).toBe(1);
});
it("rejects a live photo ZIP with no image entry", async () => {
const zip = zipSync({ "video.mov": patternBytes(900, 82) });
const t = setup(zip, { fileType: "livePhoto", hash: livePhotoHash });
await expect(t.run()).rejects.toThrow(
/file 999: live photo ZIP does not hold both an image and a video/,
);
expect(readdirSync(t.dir)).toEqual([]);
});
it("rejects a live photo ZIP with no video entry", async () => {
const zip = zipSync({ "image.heic": patternBytes(500, 81) });
const t = setup(zip, { fileType: "livePhoto", hash: livePhotoHash });
await expect(t.run()).rejects.toThrow(
/file 999: live photo ZIP does not hold both an image and a video/,
);
expect(readdirSync(t.dir)).toEqual([]);
});
});