[FFmpeg-devel] [PATCH] libavformat/hls: Observe Set-Cookie headers

[wm4]

On Sat, 6 May 2017 14:28:10 -0400
Micah Galizia <micahgalizia at gmail.com> wrote:

> On 2017-05-05 09:28 PM, wm4 wrote:
> > On Fri,  5 May 2017 20:55:05 -0400
> > Micah Galizia <micahgalizia at gmail.com> wrote:
> >  
> >> Signed-off-by: Micah Galizia <micahgalizia at gmail.com>
> >> ---
> >>   libavformat/hls.c | 12 ++++++++++--
> >>   1 file changed, 10 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/libavformat/hls.c b/libavformat/hls.c
> >> index bac53a4350..bda9abecfa 100644
> >> --- a/libavformat/hls.c
> >> +++ b/libavformat/hls.c
> >> @@ -630,8 +630,16 @@ static int open_url(AVFormatContext *s, AVIOContext **pb, const char *url,
> >>       ret = s->io_open(s, pb, url, AVIO_FLAG_READ, &tmp);
> >>       if (ret >= 0) {
> >>           // update cookies on http response with setcookies.
> >> -        void *u = (s->flags & AVFMT_FLAG_CUSTOM_IO) ? NULL : s->pb;
> >> -        update_options(&c->cookies, "cookies", u);
> >> +        char *new_cookies = NULL;
> >> +
> >> +        if (s->flags ^ AVFMT_FLAG_CUSTOM_IO)
> >> +            av_opt_get(*pb, "cookies", AV_OPT_SEARCH_CHILDREN, (uint8_t**)&new_cookies);  
> > Did you mean & instead of ^?  
> 
> No, the original code was structured to set *u to null (and thus did not 
> copy cookies) iff AVFMT_FLAG_CUSTOM_IO was set in the flags.  So using ^ 
> is logically equivalent -- cookies are copied only if 
> AVFMT_FLAG_CUSTOM_IO is not set.
> 
> > Did you find out yet what difference AVFMT_FLAG_CUSTOM_IO is supposed
> > to make in the existing code?  
> Yes, I wrote back about it a day or two ago... here is the reference to 
> its original inclusion: 
> https://lists.ffmpeg.org/pipermail/ffmpeg-trac/2013-February/013020.html. 
> When the code was originally implemented we were using s->pb->opaque, 
> which in FFMPEG we could assume was a URLContext with options (one of 
> them possibly being "cookies").
> 
> Based on the email above, that wasn't true for other apps like mplayer, 
> and could cause crashes trying to treat opaque as a URLContext. So that 
> is the purpose of checking the AVFMT_FLAG_CUSTOM_IO flag (way back in 2013).
> 
> Now though, we don't seem to touch opaque at all. The options are stored 
> in AVIOContext's av_class, which does have options.  Based on this I 
> think both patches are safe: this version has less change, but the 
> original gets rid of the check against AVFMT_FLAG_CUSTOM_IO that I don't 
> think we need anymore.
> 
> I hope that clears things up.

Sorry, I missed that. I guess this code is an artifact of some severely
unclean hook up of the AVOPtion API to AVIOContext, that breaks with
custom I/O. I guess your patch is fine then.

I just wonder how an API user is supposed to pass along cookies then.
My code passes an AVDictionary via a "cookies" entry when opening the
HLS demuxer with custom I/O, so I was wondering whether the patch
changes behavior here.