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

[Micah Galizia]

On Sat, May 20, 2017 at 9:36 PM, Micah Galizia <micahgalizia at gmail.com> wrote:
> On 2017-05-17 05:23 AM, wm4 wrote:
>>
>> 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.
>
>
> I wouldn't have expected anyone to pass the cookies to the HLS demuxer
> directly -- there is an http protocol AVOption that should pass it along to
> the demuxer. But I guess thats the whole point of the custom IO, right? It'd
> replace the http demuxer?
>
> Even so, I don't think this is a good reason to hold up the the patch - it
> corrects the problem for apps that use the http protocol and maintains the
> existing behavior -- cookies are not (and were not) copied when the custom
> flag is set because u was set to null. Am I wrong in that interpretation of
> the existing behavior?

Hi,

What else do I need to do to get this fix checked in?

Thanks
-- 
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cause, while the mark of the mature man is that he wants to live
humbly for one."   --W. Stekel