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fix(sync): treat an oversized WebDAV fence response as an absent fence so encryption transitions can start (#1113)
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Lines changed: 47 additions & 4 deletions

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‎docs/release-notes/unreleased.md‎

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@@ -171,3 +171,4 @@ Changes collected after `v1.2.1` and before the next version tag.
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- Android File Sync: on document providers that decorate new file names (typically appending ".bin" to the temporary write files), every sync failed with "was created or renamed by another writer" and kept requeueing. The temporary file is now renamed back to its exact name instead of being treated as another device's write; real concurrent writes are still detected. (#1113)
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- Desktop: the priority color strip on task rows now sits in the row's left padding instead of directly against the checkbox, matching mobile's spacing.
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- Sync encryption setup: after adding a sync location that already holds encrypted data, the Encryption section now switches to "enter your existing passphrase" as soon as the first sync or connection test discovers it, instead of still offering to set a new passphrase until an enable attempt failed. Desktop and mobile. (#1001)
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- Sync encryption could not be enabled (or disabled) on WebDAV servers that answer a request for a missing file with a web page instead of "not found" (reported with Koofr): the transition stopped at "Response exceeds the 4096 byte download limit" before doing anything. Such a response is now treated as the file being absent; protection against two devices transitioning at once is unchanged. (#1113)

‎packages/core/src/sync-remote-fence-providers.test.ts‎

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@@ -77,3 +77,26 @@ describe('remote mutation fence provider ports', () => {
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});
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});
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});
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describe('oversized fence responses (#1113)', () => {
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it('reads a non-404 response too large to be a fence as an absent file', async () => {
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// Koofr answers the GET for a missing file with a large HTML page instead
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// of 404; before the fix this rejected with ResponseTooLargeError and no
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// encryption transition could start.
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const hugeHtml = `<html>${'x'.repeat(8_192)}</html>`;
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const fetcher = vi.fn(async () => new Response(hugeHtml, {
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status: 200,
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headers: { date: SERVER_DATE, 'content-type': 'text/html' },
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})) as unknown as typeof fetch;
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const port = createWebdavSyncRemoteMutationFencePort(
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'https://dav.example/root/data.json',
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{ fetcher },
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);
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await expect(port.read()).resolves.toEqual({
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bytes: null,
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version: null,
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serverNowMs: Date.parse(SERVER_DATE),
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});
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});
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});

‎packages/core/src/sync-remote-fence-providers.ts‎

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@@ -33,7 +33,10 @@ export const createWebdavSyncRemoteMutationFencePort = (
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options: WebDavOptions = {},
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): SyncRemoteMutationFencePort => {
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const url = webdavMutationFenceUrl(documentUrl);
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const readOptions: WebDavOptions = { ...options, maxBytes: FENCE_MAX_BYTES };
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// A response bigger than a fence record cannot be one. Koofr answers the GET for a
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// missing file with a large HTML page instead of 404 (#1113); reading it as absent
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// keeps acquisition safe because the follow-up write is create-only conditional.
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const readOptions: WebDavOptions = { ...options, maxBytes: FENCE_MAX_BYTES, treatOversizeAsAbsent: true };
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return {
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read: () => webdavGetFileVersionedWithServerTime(url, readOptions),
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write: (bytes, expectedVersion) => webdavPutFileVersioned(

‎packages/core/src/webdav.ts‎

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Original file line numberDiff line numberDiff line change
@@ -1,4 +1,5 @@
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import {
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ResponseTooLargeError,
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DEFAULT_TIMEOUT_MS,
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assertConnectionAllowed,
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createProgressStream,
@@ -40,6 +41,12 @@ export interface WebDavOptions {
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/** Internal one-shot write mode. A legacy plaintext document without a usable
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* generation cannot safely retry after an ambiguous response. */
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disableParentCollectionRetry?: boolean;
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/** Fence reads only: a body larger than maxBytes cannot be a fence record, and some
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* servers (Koofr, #1113) answer the GET for a missing file with a large HTML page
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* instead of 404. Reports such a response as an absent file; the caller's create-only
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* conditional write still guards against a real racing peer. Never set this for a
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* document read - an oversized document must fail, not read as absent. */
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treatOversizeAsAbsent?: boolean;
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}
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export type RemoteFileMetadata = {
@@ -939,13 +946,22 @@ export async function webdavGetFileVersionedWithServerTime(
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(error as { status?: number }).status = res.status;
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throw error;
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}
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return {
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bytes: new Uint8Array(await readResponseBody(
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let body: ArrayBuffer;
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try {
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body = await readResponseBody(
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res,
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options.onProgress,
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options.maxBytes ?? MAX_DOWNLOAD_BYTES,
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signal,
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)),
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);
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} catch (error) {
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if (options.treatOversizeAsAbsent && error instanceof ResponseTooLargeError) {
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return { bytes: null, version: null, serverNowMs };
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}
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throw error;
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}
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return {
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bytes: new Uint8Array(body),
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version: normalizeStrongWebdavEtag(res.headers.get('etag')),
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serverNowMs,
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};

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