Re: Failed to open tun socket in namespace

["Gianluca Stivan" <me@yawnt.com>]

Thanks for the reply, I'll give that a go and report back!
Apologies, it seems my unusual use case is causing some headaches :)

Kernel version: 5.19.0-35-generic (just a boring Ubuntu 22.04).

Cheers,

On Mon, Mar 27, 2023, at 14:02, Stefano Brivio wrote:
> On Mon, 27 Mar 2023 13:22:12 +0100
> "Gianluca Stivan" <me@yawnt.com> wrote:
>
>> Thanks for the reply!
>> 
>> Here is the ending of the log file:
>> 
>> ...
>> <a lot a lot of STALLED and dropped...>
>> 3944.3562:          TCP: index 19, timer expires in 2.000s
>> 3944.3563:          TCP: index 19, timer expires in 2.000s
>> 3944.3566:          TCP: index 19: STALLED
>> 3944.3578:          TCP: index 7: STALLED dropped
>> 3944.3579:          TCP: index 7, timer expires in 2.000s
>> 3944.3584:          TCP: index 7: STALLED
>> 3944.3586:          TCP: index 7: STALLED dropped
>> 3944.3587:          TCP: index 7: ACK_FROM_TAP_DUE dropped
>> 3944.3588:          TCP: index 7: ACK_FROM_TAP_DUE
>> 3944.3588:          TCP: index 7, timer expires in 2.000s
>> 3944.3589:          TCP: index 12: STALLED dropped
>> 3944.3590:          TCP: index 12, timer expires in 2.000s
>> 3944.3620:          tap write: No buffer space available
>> 3944.3620:          TCP: index 17: STALLED dropped
>> 3944.3620:          TCP: index 17: ACK_FROM_TAP_DUE dropped
>> 3944.4420: ERROR:   Failed to open tun socket in namespace
>> 
>> No buffer space available seems interesting?
>
> Interesting, I had never seen ENOBUFS from a tap file descriptor. Let me
> find out where it might come from (and how pasta should react to it),
> it might take a bit. What kernel version are you using by the way?
>
> I mean, maybe we just have to try again (as if we received EAGAIN):
>
> diff --git a/tap.c b/tap.c
> index 68ef480..21a786d 100644
> --- a/tap.c
> +++ b/tap.c
> @@ -323,7 +323,8 @@ static size_t tap_send_frames_pasta(struct ctx *c,
>                 if (write(c->fd_tap, (char *)iov[i].iov_base,
>                           iov[i].iov_len) < 0) {
>                         debug("tap write: %s", strerror(errno));
> -                       if (errno != EAGAIN && errno != EWOULDBLOCK)
> +                       if (errno != EAGAIN && errno != EWOULDBLOCK &&
> +                           errno != ENOBUFS)
>                                 tap_handler(c, c->fd_tap, EPOLLERR, NULL);
>                         i--;
>                 }
>
> but I'm not sure it's correct. You could probably try that as a
> workaround meanwhile.
>
>> PS: let me know if you'd like the full file!
>
> No no, thank you, that was enough!
>
> About issue number 2. (the fact that we can't actually close and reopen
> the tap file descriptor after this failure), I'll check if I can easily
> reproduce that in a Podman setting.
>
> -- 
> Stefano