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

[Micah Galizia]

On 2017-05-28 08:44 PM, Michael Niedermayer wrote:
> On Fri, May 26, 2017 at 09:29:04PM -0400, Micah Galizia wrote:
>> 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?
> patch applied
>
> thx

TYVM!