[vlc-devel] 答复: [PATCH] core: network: recover from reading on invalid sockets
Steve Lhomme
robux4 at ycbcr.xyz
Wed Jan 16 09:13:33 CET 2019
Do these patches fix your issue ?
https://patches.videolan.org/patch/13959/
https://patches.videolan.org/patch/13960/
https://patches.videolan.org/patch/13961/
On 16/01/2019 07:19, Xie Zhigang wrote:
> Hi,
>
> Exactly YES, it is related to https://trac.videolan.org/vlc/ticket/21153 .
>
> WSAEventSelect() does not get the FD_CLOSE event, and the poll() is in dysfunctional state
> if remote server TCP RST the connection. I have dumped the traffic data as resuming the play:
>
> #28362 30.011007 TCP 68 38912 → 80 [ACK] Seq=350 Ack=21995213 Win=768 Len=0 TSval=4568331 TSecr=555407
> #28392 30.236684 TCP 836 [TCP Window Full] 80 → 38912 [PSH, ACK] Seq=21995213 Ack=350 Win=30080 Len=768 TSval=555474 TSecr=4568331 [TCP segment of a reassembled PDU]
> #28393 30.236717 TCP 68 [TCP ZeroWindow] 38912 → 80 [ACK] Seq=350 Ack=21995981 Win=0 Len=0 TSval=4568387 TSecr=555474
> #28394 30.460288 TCP 68 [TCP Keep-Alive] 80 → 38912 [ACK] Seq=21995980 Ack=350 Win=30080 Len=0 TSval=555530 TSecr=4568387
> #28395 30.460300 TCP 68 [TCP ZeroWindow] 38912 → 80 [ACK] Seq=350 Ack=21995981 Win=0 Len=0 TSval=4568443 TSecr=555474
> #28396 30.908290 TCP 68 [TCP Keep-Alive] 80 → 38912 [ACK] Seq=21995980 Ack=350 Win=30080 Len=0 TSval=555642 TSecr=4568443
> #28397 31.804538 TCP 68 [TCP Keep-Alive] 80 → 38912 [ACK] Seq=21995980 Ack=350 Win=30080 Len=0 TSval=555866 TSecr=4568443
> #28398 31.804564 TCP 68 [TCP ZeroWindow] 38912 → 80 [ACK] Seq=350 Ack=21995981 Win=0 Len=0 TSval=4568779 TSecr=555474
> #28399 33.600277 TCP 68 [TCP Keep-Alive] 80 → 38912 [ACK] Seq=21995980 Ack=350 Win=30080 Len=0 TSval=556315 TSecr=4568779
> #28400 33.600290 TCP 68 [TCP ZeroWindow] 38912 → 80 [ACK] Seq=350 Ack=21995981 Win=0 Len=0 TSval=4569228 TSecr=555474
> #28401 37.188314 TCP 68 [TCP Keep-Alive] 80 → 38912 [ACK] Seq=21995980 Ack=350 Win=30080 Len=0 TSval=557212 TSecr=4569228
> #28402 37.188347 TCP 68 [TCP ZeroWindow] 38912 → 80 [ACK] Seq=350 Ack=21995981 Win=0 Len=0 TSval=4570125 TSecr=555474
> #28435 44.372520 TCP 68 [TCP Keep-Alive] 80 → 38912 [ACK] Seq=21995980 Ack=350 Win=30080 Len=0 TSval=559008 TSecr=4570125
> #28436 44.372531 TCP 68 [TCP ZeroWindow] 38912 → 80 [ACK] Seq=350 Ack=21995981 Win=0 Len=0 TSval=4571921 TSecr=555474
> #28469 58.744435 TCP 68 [TCP Keep-Alive] 80 → 38912 [ACK] Seq=21995980 Ack=350 Win=30080 Len=0 TSval=562601 TSecr=4571921
> #28470 58.744451 TCP 68 [TCP ZeroWindow] 38912 → 80 [ACK] Seq=350 Ack=21995981 Win=0 Len=0 TSval=4575514 TSecr=555474
> #28561 87.508600 TCP 68 [TCP Keep-Alive] 80 → 38912 [ACK] Seq=21995980 Ack=350 Win=30080 Len=0 TSval=569792 TSecr=4575514
> #28562 87.508611 TCP 68 [TCP ZeroWindow] 38912 → 80 [ACK] Seq=350 Ack=21995981 Win=0 Len=0 TSval=4582705 TSecr=555474
> #28739 144.980525 TCP 68 [TCP Keep-Alive] 80 → 38912 [ACK] Seq=21995980 Ack=350 Win=30080 Len=0 TSval=584160 TSecr=4582705
> #28740 144.980549 TCP 68 [TCP ZeroWindow] 38912 → 80 [ACK] Seq=350 Ack=21995981 Win=0 Len=0 TSval=4597073 TSecr=555474
> #29080 259.797508 TCP 68 [TCP Keep-Alive] 80 → 38912 [ACK] Seq=21995980 Ack=350 Win=30080 Len=0 TSval=612864 TSecr=4597073
> #29081 259.797533 TCP 68 [TCP ZeroWindow] 38912 → 80 [ACK] Seq=350 Ack=21995981 Win=0 Len=0 TSval=4625777 TSecr=555474
> #34207 2022.822738 TCP 68 [TCP Window Update] 38912 → 80 [ACK] Seq=350 Ack=21995981 Win=75136 Len=0 TSval=5066533 TSecr=555474
> #34208 2022.823030 TCP 62 80 → 38912 [RST] Seq=21995981 Win=0 Len=0
>
> As we expect an FD_CLOSE event on the TCP RST traffic, but poll() is in ignorance of it.
> It is reproducible on Windows. On Linux, the poll() is in another implementation and it is ok.
>
> I found another patch to it in poll()'s windows implementation,
> that is to reset the errno at the beginning of poll() implementation.
> It seems to enable the capability of WSAEventSelect() for FD_CLOSE,
> but it is more difficult to be considered as a good fix than my first patch is:
>
> ---
> compat/poll.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/compat/poll.c b/compat/poll.c
> index 8020f7d..5ff43ea 100644
> --- a/compat/poll.c
> +++ b/compat/poll.c
> @@ -113,6 +113,8 @@ static int poll_compat(struct pollfd *fds, unsigned nfds, int timeout)
> {
> DWORD to = (timeout >= 0) ? (DWORD)timeout : INFINITE;
>
> + /* clears the errno to enable WSAEventSelect detecting the FD_CLOSE event. */
> + errno = 0;
> if (nfds == 0)
> { /* WSAWaitForMultipleEvents() does not allow zero events */
> if (SleepEx(to, TRUE))
> --
> 2.7.4
>
>
> 发件人: vlc-devel <vlc-devel-bounces at videolan.org> 代表 jeremy.vignelles at dev3i.fr <jeremy.vignelles at dev3i.fr>
> 发送时间: 2019年1月15日 23:37
> 收件人: 'Mailing list for VLC media player developers'
> 主题: Re: [vlc-devel] [PATCH] core: network: recover from reading on invalid sockets
>
> Hi,
> Is this patch related to https://trac.videolan.org/vlc/ticket/21153 ?
>
> This does not look like a proper fix for me either.
>
> Regards,
> Jérémy VIGNELLES
>
> De : vlc-devel <vlc-devel-bounces at videolan.org> De la part de Rémi Denis-Courmont
> Envoyé : mardi 15 janvier 2019 15:39
> À : Mailing list for VLC media player developers <vlc-devel at videolan.org>
> Objet : Re: [vlc-devel] [PATCH] core: network: recover from reading on invalid sockets
>
> Hi,
>
> This statistical approach oooks like it can lead to spurious failures, on all platforms. No way.
>
> The bug must be somewhere else.
> Le 15 janvier 2019 13:52:12 GMT+02:00, Xie Zhigang <mailto:zighouse at hotmail.com> a écrit :
> Fix the bug on Windows: if pausing the on-line VOD playing
> for a long time (5 minutes or so), and the remote VOD server drops the
> tcp connection, vlc_tls_Read() will be in an endless loop of retrial
> with errno as EAGAIN. Use a max retrial count to recover vlc from the
> endless reading loop.
> ________________________________________
> src/network/stream.c | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/src/network/stream.c b/src/network/stream.c
> index 6e015d5..7324f78 100644
> --- a/src/network/stream.c
> +++ b/src/network/stream.c
> @@ -55,6 +55,7 @@ ssize_t vlc_tls_Read(vlc_tls_t *session, void *buf, size_t len, bool waitall)
> {
> struct pollfd ufd;
> struct iovec iov;
> + int turn = 0;
>
> ufd.events = POLLIN;
> ufd.fd = vlc_tls_GetPollFD(session, &ufd.events);
> @@ -89,6 +90,12 @@ ssize_t vlc_tls_Read(vlc_tls_t *session, void *buf, size_t len, bool waitall)
> }
>
> vlc_poll_i11e(&ufd, 1, -1);
> + /*
> + * Use an arbitrary max retrial count (10) to recover from endless loop
> + * on an invalid connection.
> + */
> + if (++turn > 10)
> + return rcvd ? (ssize_t)rcvd : -1;
> }
> }
>
>
> --
> Envoyé de mon appareil Android avec Courriel K-9 Mail. Veuillez excuser ma brièveté.
>
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