[FFmpeg-devel] AVRandomState usage in ffserver/RTP/RTSP

[Stefano Sabatini]

On date Monday 2009-01-26 21:13:08 +0100, Stefano Sabatini encoded:
> On date Wednesday 2009-01-21 22:26:30 +0100, Stefano Sabatini encoded:
> > On date Wednesday 2009-01-21 21:13:49 +0100, Michael Niedermayer encoded:
> > > On Wed, Jan 21, 2009 at 08:21:58PM +0100, Stefano Sabatini wrote:
> > > > On date Tuesday 2009-01-20 12:01:36 -0800, Baptiste Coudurier encoded:
> > > > > Stefano Sabatini wrote:
> > > > > > On date Monday 2009-01-19 00:18:04 +0100, Stefano Sabatini encoded:
> > > > > >> On date Tuesday 2009-01-06 22:50:44 +0100, Stefano Sabatini encoded:
> > > > > > [...]
> > > > > >>> Index: ffmpeg/ffserver.c
> > > > > >>> ===================================================================
> > > > > >>> --- ffmpeg.orig/ffserver.c	2009-01-05 17:24:43.000000000 +0100
> > > > > >>> +++ ffmpeg/ffserver.c	2009-01-05 17:31:35.000000000 +0100
> > > > > >>> @@ -4468,6 +4468,7 @@
> > > > > >>>  int main(int argc, char **argv)
> > > > > >>>  {
> > > > > >>>      struct sigaction sigact;
> > > > > >>> +    struct timeval tv;
> > > > > >>>  
> > > > > >>>      av_register_all();
> > > > > >>>  
> > > > > >>> @@ -4483,7 +4484,8 @@
> > > > > >>>  
> > > > > >>>      unsetenv("http_proxy");             /* Kill the http_proxy */
> > > > > >>>  
> > > > > >>> -    av_random_init(&random_state, av_gettime() + (getpid() << 16));
> > > > > >>> +    gettimeofday(&tv, NULL);
> > > > > >>> +    av_random_init(&random_state, tv.tv_usec);
> > > > > >>>  
> > > > > >>>      memset(&sigact, 0, sizeof(sigact));
> > > > > >>>      sigact.sa_handler = handle_child_exit;
> > > > > >> Ping?
> > > > > > 
> > > > > > Ping2.
> > > > > > 
> > > > > 
> > > > > I'd say it's better, yes, any other opinion ?
> > > > 
> > > > I'd say if it's OK with you and there are no better ideas I'll
> > > > apply it in a week.
> > > 
> > > i suggest /dev/(u)random, if its unavailable something less good can always
> > > be used as fallback
> > 
> > Uh, what about this?
> > 
> > Regards.
> > -- 
> > FFmpeg = Frightening & Fostering Moronic Prodigious Evanescent Gadget
> 
> > Index: ffserver.c
> > ===================================================================
> > --- ffserver.c	(revision 16713)
> > +++ ffserver.c	(working copy)
> > @@ -4467,6 +4467,24 @@
> >      { NULL },
> >  };
> >  
> > +static unsigned int get_random_uint()
> > +{
> > +    struct timeval tv;
> > +    unsigned int ret;
> > +    int size = sizeof(ret);
> > +    int fd = open("/dev/urandom", O_RDONLY);
> > +
> > +    if (fd < 0 || read(fd, &ret, size) < size) {
> > +        /* cannot read from /dev/urandom, fallback to timeval microseconds */
> > +        gettimeofday(&tv, NULL);
> > +        ret = tv.tv_usec;
> > +    }
> > +    if (fd >= 0)
> > +        close(fd);
> > +
> > +    return ret;
> > +}
> > +
> >  int main(int argc, char **argv)
> >  {
> >      struct sigaction sigact;
> > @@ -4485,7 +4503,7 @@
> >  
> >      unsetenv("http_proxy");             /* Kill the http_proxy */
> >  
> > -    av_random_init(&random_state, av_gettime() + (getpid() << 16));
> > +    av_random_init(&random_state, get_random_uint());
> >  
> >      memset(&sigact, 0, sizeof(sigact));
> >      sigact.sa_handler = handle_child_exit;
> 
> Ping.

Ping2.

Rethinking at it, maybe something more general like:

int av_random_write(uint8_t *dst, unsigned int *dst_size);

would be more appropriate?

Regards.
-- 
FFmpeg = Fierce Fantastic MultiPurpose Energized Gorilla