[FFmpeg-devel] [PATCH] avformat/dashdec: only limit DASH manifest size according to AVBprint limits

[Jan Ekström]

On Sat, Sep 5, 2020 at 1:12 AM Steven Liu <lingjiujianke at gmail.com> wrote:
>
> Jan Ekström <jeebjp at gmail.com> 于2020年9月4日周五 上午2:33写道：
> >
> > Currently the API is internally limited to unsigned integers, so if we
> > limit the file size as well as the amount to read to UINT_MAX - 1, we
> > do not require additional limiting to be performed on the values.
> >
> > This change is based on the fact that initially the 8*1024 value added
> > in 96d70694aea64616c68db8be306c159c73fb3980 was only for the case where
> > the file size was not known. It was not a maximum file size limit.
> >
> > In 29121188983932f79aef8501652630d322a9974c this was reworked to be
> > a maximum manifest file size limit, while its commit message appears
> > to only note that it added support for larger manifest file sizes.
> >
> > This should enable various unfortunately large MPEG-DASH manifests,
> > such as Youtube's multi-megabyte live stream archives to load up
> > as well as bring back the original intent of the logic.
> > ---
> >  libavformat/dashdec.c | 10 ++++++----
> >  1 file changed, 6 insertions(+), 4 deletions(-)
> >
> > diff --git a/libavformat/dashdec.c b/libavformat/dashdec.c
> > index c5a5ff607b..1e9985f32c 100644
> > --- a/libavformat/dashdec.c
> > +++ b/libavformat/dashdec.c
> > @@ -29,7 +29,7 @@
> >  #include "dash.h"
> >
> >  #define INITIAL_BUFFER_SIZE 32768
> > -#define MAX_MANIFEST_SIZE 50 * 1024
> > +#define MAX_BPRINT_READ_SIZE (UINT_MAX - 1)
> >  #define DEFAULT_MANIFEST_SIZE 8 * 1024
> >
> >  struct fragment {
> > @@ -1256,14 +1256,16 @@ static int parse_manifest(AVFormatContext *s, const char *url, AVIOContext *in)
> >      }
> >
> >      filesize = avio_size(in);
> > -    if (filesize > MAX_MANIFEST_SIZE) {
> > +    filesize = filesize > 0 ? filesize : DEFAULT_MANIFEST_SIZE;
> > +
> > +    if (filesize > MAX_BPRINT_READ_SIZE) {
> >          av_log(s, AV_LOG_ERROR, "Manifest too large: %"PRId64"\n", filesize);
> >          return AVERROR_INVALIDDATA;
> >      }
> >
> > -    av_bprint_init(&buf, (filesize > 0) ? filesize + 1 : DEFAULT_MANIFEST_SIZE, AV_BPRINT_SIZE_UNLIMITED);
> > +    av_bprint_init(&buf, filesize + 1, AV_BPRINT_SIZE_UNLIMITED);
> >
> > -    if ((ret = avio_read_to_bprint(in, &buf, MAX_MANIFEST_SIZE)) < 0 ||
> > +    if ((ret = avio_read_to_bprint(in, &buf, MAX_BPRINT_READ_SIZE)) < 0 ||
> >          !avio_feof(in) ||
> >          (filesize = buf.len) == 0) {
> >          av_log(s, AV_LOG_ERROR, "Unable to read to manifest '%s'\n", url);
> > --
> > 2.26.2
> >
> > _______________________________________________
> > ffmpeg-devel mailing list
> > ffmpeg-devel at ffmpeg.org
> > https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
> >
> > To unsubscribe, visit link above, or email
> > ffmpeg-devel-request at ffmpeg.org with subject "unsubscribe".
>
> Not proficient in English, but code looks ok. :D
>
>
> Thanks jeeb
>
>
> Steven

Thanks, applied as 3249c757aed678780e22e99a1a49f4672851bca9 with the
updated commit message.

Jan