[vlc-devel] [PATCH 1/2] access/rtp: define MSG_TRUNC on recv call if available.

[Ilkka Ollakka]

On Sun, Oct 14, 2018 at 12:16:23PM +0300, Rémi Denis-Courmont wrote:
> Le lauantaina 13. lokakuuta 2018, 21.04.43 EEST Ilkka Ollakka a écrit :
> > Defining the MSG_TRUNC on msghrd does only tell if data is truncated,
> > not what the actual data size was.

> > Tested the adjust of MTU by sending data to localhost via netcat:

> > cat ~/tmp/myfile.mp3|netcat -u 127.0.0.1 1234

> > and vlc -Idummy -vv rtp://@127.0.0.1:1234 --sout="#stat"

> > without this patch the rtp input constantly complains about trunced
> > input and doesn't adjust the receiving amount.

> I would add 'const', and maybe clarify the description because it took me some 
> time to figure out what the problem and solution was here.

Thanks, I reworded the description.

> But looks OK.

> > ---
> >  modules/access/rtp/input.c | 18 +++++++++---------
> >  1 file changed, 9 insertions(+), 9 deletions(-)

> > diff --git a/modules/access/rtp/input.c b/modules/access/rtp/input.c
> > index f22f6655ab..be23e3b3e6 100644
> > --- a/modules/access/rtp/input.c
> > +++ b/modules/access/rtp/input.c
> > @@ -109,6 +109,12 @@ void *rtp_dgram_thread (void *opaque)
> >      demux_sys_t *sys = demux->p_sys;
> >      vlc_tick_t deadline = VLC_TICK_INVALID;
> >      int rtp_fd = sys->fd;
> > +#ifdef __linux__
> > +    int trunc_flag = MSG_TRUNC;
> > +#else
> > +    int trunc_flag = 0;
> > +#endif
> > +
> >      struct iovec iov =
> >      {
> >          .iov_len = DEFAULT_MRU,
> > @@ -149,17 +155,12 @@ void *rtp_dgram_thread (void *opaque)
> >              }

> >              iov.iov_base = block->p_buffer;
> > -#ifdef __linux__
> > -            msg.msg_flags = MSG_TRUNC;
> > -#else
> > -            msg.msg_flags = 0;
> > -#endif
> > +            msg.msg_flags = trunc_flag;

> > -            ssize_t len = recvmsg (rtp_fd, &msg, 0);
> > +            ssize_t len = recvmsg (rtp_fd, &msg, trunc_flag);
> >              if (len != -1)
> >              {
> > -#ifdef MSG_TRUNC
> > -                if (msg.msg_flags & MSG_TRUNC)
> > +                if (msg.msg_flags & trunc_flag )
> >                  {
> >                      msg_Err(demux, "%zd bytes packet truncated (MRU was
> > %zu)", len, iov.iov_len);
> > @@ -167,7 +168,6 @@ void *rtp_dgram_thread (void *opaque)
> >                      iov.iov_len = len;
> >                  }
> >                  else
> > -#endif
> >                      block->i_buffer = len;

> >                  rtp_process (demux, block);
-- 
Ilkka Ollakka
The number of computer scientists in a room is inversely proportional
to the number of bugs in their code.
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