Page links played here only also go through a reader of their own: Bilibili's cuts never end playback

Alone, or with Everyone fetches it, a page link with plain-file tracks
plays through SharedLinks.local (a SharedSource without the upload): it
resumes after a cut, backs off on 412/429/5xx and resolves the page again
on 403/410/412, where ffmpeg's own reconnect gave up for good. Pieces
tracks and a reader that cannot open keep yt-dlp's URLs as before.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
This commit is contained in:
foxyzandClaude Opus 5.5 committed 2026-10-18 17:33:31 +03:00
1 parent f2721d125c
commit 4c8ddeb034
5 files changed
+183 -16

No files matched your search

+88 -11
View File
@@ -34,6 +34,14 @@ class _Cdn {
final Map<String, String> _files;
int ok = 0, forbidden = 0;
final cookies = <String?>[];
final agents = <String?>[];
/// Like Bilibili cutting a long read: a response stops after this many
/// bytes (the connection dropped), and the next request after a cut is
/// refused with 412 (where ffmpeg's reconnect gives up). Null: whole.
int? cutAfter;
bool _cut = false;
int cuts = 0, refused = 0;
String url(String name) => 'http://127.0.0.1:${_server.port}/$name';
@@ -61,12 +69,21 @@ class _Cdn {
await res.close();
return;
}
if (_cut) {
_cut = false;
refused++;
res.statusCode = HttpStatus.preconditionFailed;
await res.close();
return;
}
ok++;
cookies.add(req.headers.value('cookie'));
agents.add(req.headers.value('user-agent'));
final bytes = await File(file).readAsBytes();
var start = 0, end = bytes.length - 1;
final range = RegExp(r'bytes=(\d*)-(\d*)').firstMatch(req.headers.value('range') ?? '');
res.headers.set('accept-ranges', 'bytes');
res.headers.contentType = ContentType('video', 'mp4');
if (range != null) {
start = int.tryParse(range[1]!) ?? 0;
end = int.tryParse(range[2]!) ?? end;
@@ -74,6 +91,23 @@ class _Cdn {
res.headers.set('content-range', 'bytes $start-$end/${bytes.length}');
}
res.contentLength = end - start + 1;
final cut = cutAfter;
if (cut != null && end - start + 1 > cut) {
// Headers by hand on the raw socket, part of the body, then dropped.
final socket = await res.detachSocket(writeHeaders: false);
final status = range == null ? '200 OK' : '206 Partial Content';
socket.add(utf8.encode('HTTP/1.1 $status\r\naccept-ranges: bytes\r\ncontent-type: video/mp4\r\n'
'${range == null ? '' : 'content-range: bytes $start-$end/${bytes.length}\r\n'}'
'content-length: ${end - start + 1}\r\nconnection: close\r\n\r\n'));
socket.add(bytes.sublist(start, start + cut));
_cut = true;
cuts++;
try {
await socket.flush();
} catch (_) {}
socket.destroy();
return;
}
res.add(bytes.sublist(start, end + 1));
await res.close();
}
@@ -88,16 +122,19 @@ Future<AppYtDlp> _fakeYtDlp(_Cdn cdn, {required bool headers, bool fail = false}
if (dir.existsSync()) dir.deleteSync(recursive: true);
dir.createSync(recursive: true);
final h = headers ? {'Referer': _referer, 'User-Agent': 'fake-agent'} : <String, String>{};
final formats = [
{'format_id': 'v', 'url': cdn.url('v.m4s'), 'protocol': 'https', 'ext': 'mp4',
'vcodec': 'avc1.64001F', 'acodec': 'none', 'width': 320, 'height': 180, 'http_headers': h,
'cookies': 'SESSDATA=abc; Domain=.127.0.0.1; Path=/'},
{'format_id': 'a', 'url': cdn.url('a.m4s'), 'protocol': 'https', 'ext': 'm4a',
'vcodec': 'none', 'acodec': 'mp4a.40.2', 'http_headers': h,
'cookies': 'SESSDATA=abc; Domain=.127.0.0.1; Path=/'},
];
final json = jsonEncode({
'id': 'BV1', 'title': 'Fake page', 'duration': 30, 'extractor': 'fake',
'format_id': 'v+a', 'ext': 'mp4',
'requested_formats': [
{'format_id': 'v', 'url': cdn.url('v.m4s'), 'protocol': 'https', 'ext': 'mp4',
'vcodec': 'avc1.64001F', 'acodec': 'none', 'width': 320, 'height': 180, 'http_headers': h,
'cookies': 'SESSDATA=abc; Domain=.127.0.0.1; Path=/'},
{'format_id': 'a', 'url': cdn.url('a.m4s'), 'protocol': 'https', 'ext': 'm4a',
'vcodec': 'none', 'acodec': 'mp4a.40.2', 'http_headers': h},
],
'formats': formats,
'requested_formats': formats,
'requested_subtitles': {
'en': {'url': cdn.url('en.vtt'), 'ext': 'vtt', 'name': 'English'},
'danmaku': {'url': cdn.url('danmaku.xml'), 'ext': 'xml'},
@@ -124,8 +161,9 @@ void main() {
tearDownAll(() => server.close(force: true));
// A page "everyone fetches" opens through the app's own resolve: its
// stream URLs (an EDL of video + audio) with the CDN's headers; mpv's
// yt-dlp hook is off.
// stream URLs (video + audio) read by the app's own reader
// (SharedLinks.local) with the CDN's headers and cookies, mpv on its
// loopback EDL; mpv's yt-dlp hook is off.
test(
"a page plays from yt-dlp's stream URLs with each CDN's Referer and the cookies; subtitles but danmaku",
timeout: const Timeout(Duration(minutes: 1)),
@@ -146,6 +184,8 @@ void main() {
expect(cdn.forbidden, 0, reason: 'every request had the Referer');
expect(cdn.ok, greaterThanOrEqualTo(2));
expect(cdn.cookies, everyElement('SESSDATA=abc'));
expect(m.shared.hasLocal(cdn.page('BV1fake')), isTrue);
expect(cdn.agents, everyElement(startsWith('fake-agent')), reason: 'the reader sends the format\'s headers');
expect(cdn.subtitles, 1, reason: 'the page\'s subtitles are added, danmaku is not');
await _until(() => p.tracks.peek().any((t) => t.isExternal), 'the subtitle track listed');
} finally {
@@ -185,6 +225,43 @@ void main() {
skip: Platform.isLinux ? false : 'fake yt-dlp is a shell script',
);
// Bilibili cuts a long read and refuses the reconnect right after it
// (412): ffmpeg's own reconnect ends playback there ("Stream ends
// prematurely", "Operation not permitted"); the reader resumes after a
// back-off and the player never sees the cut.
test(
'a CDN that cuts reads and refuses the reconnect (412): played to the end without an error',
timeout: const Timeout(Duration(minutes: 1)),
() async {
final m = MediaPipeline(host: MediaKitHost()..init(), links: await _fakeYtDlp(cdn, headers: true));
final p = m.playback;
final errors = <String>[];
p.onLoadError = errors.add;
m.onError = (raw, {cookies}) => errors.add(raw);
cdn.cutAfter = 48 * 1024;
final cutsBefore = cdn.cuts;
try {
await m.start();
final page = cdn.page('BV4fake');
expect(await m.open(page), isTrue);
await _until(() => p.duration.peek() > Duration.zero, 'opened', secs: 20);
await p.player.setProperty('speed', '8');
await p.player.play();
await _until(() => p.positionSecs > 25 || p.player.state.completed, 'played to the end', secs: 30);
// ignore: avoid_print
print('cuts: ${cdn.cuts - cutsBefore}, refused: ${cdn.refused}, errors: $errors');
expect(cdn.cuts - cutsBefore, greaterThan(2), reason: 'the CDN did cut');
expect(cdn.refused, greaterThan(0));
expect(errors, isEmpty);
expect(m.shared.hasLocal(page), isTrue);
} finally {
cdn.cutAfter = null;
await m.dispose();
}
},
skip: Platform.isLinux ? false : 'fake yt-dlp is a shell script',
);
// D11: yt-dlp finds no video; the error names the cookies it used.
test('a page yt-dlp finds no video on: the error says which cookies were used', () async {
final m = MediaPipeline(host: MediaKitHost()..init(), links: await _fakeYtDlp(cdn, headers: true, fail: true));
@@ -203,8 +280,8 @@ void main() {
}, skip: Platform.isLinux ? false : 'fake yt-dlp is a shell script');
}
Future<void> _until(bool Function() cond, String what) async {
final end = DateTime.now().add(const Duration(seconds: 10));
Future<void> _until(bool Function() cond, String what, {int secs = 10}) async {
final end = DateTime.now().add(Duration(seconds: secs));
while (!cond()) {
if (DateTime.now().isAfter(end)) fail('timed out waiting for $what');
await Future.delayed(const Duration(milliseconds: 100));