view_video.php took the end of the range straight from the request and never
checked it against the file:
if (!empty($matches[2])) $end = intval($matches[2]);
$length = $end - $begin + 1;
so on a 1000 byte file:
bytes=0-99999 206, Content-Length 100000, body 1000 bytes
bytes=5000-6000 206, Content-Range naming bytes that do not exist
bytes=500-100 206, Content-Length -399
bytes=1000- 206, Content-Length 0
bytes=-100 200 with the whole file, not the last 100 bytes
A client that is told to expect 100000 bytes and gets 1000 does not see a bad
request, it sees a truncated file, and reports the video as broken. The suffix
form was not recognised at all because the pattern required a digit before the
dash.
This is reached once per fragment by the byte-range HLS manifest VideoStore
writes, every fragment being a Range against the one mp4, so a player that
asks for anything the file cannot supply gets a body that does not match its
own Content-Length rather than an answer it can act on.
Parse the header properly: clamp a range that runs past the end, because a
client may ask for more than is there and is entitled to what is there;
answer 416 with "Content-Range: bytes */size" when the range cannot be
satisfied at all, so the client learns the real length; and read "-N" as the
last N bytes. Length is now derived from the range being served rather than
the one requested, and the send loop counts down by the bytes it actually
read, so Content-Length and the body cannot disagree.
Only the first range of a multi-range request is served, as before. A
multipart/byteranges body is not worth building for this, and falling back to
sending the whole representation is not an option when these are event videos
of hundreds of megabytes; Content-Range names exactly what was sent.
The parsing is its own dependency-free include so it can be tested without a
database, and tests/php/test_http_range.php covers each case above plus a
sweep asserting that every range it ever returns lies inside the file.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
