Re: [Qemu-devel] [PATCH] [tftp] Handle TFTP ERROR from client

[Anthony Liguori]

On 01/07/2010 11:01 AM, Thomas Horsten wrote:
> If a PXE client only wants to find out the size of a file, it will
> open the file and then abort the transfer by sending a TFTP ERROR packet.
>
> The ERROR packet should cause qemu to terminate the session. If not,
> the sessions will soon run out and cause timeouts in the client.
>
> Also, if a TFTP session already exists with same IP/UDP port, it
> should be terminated when a new RRQ is received, instead of creating a
> duplicate (which will never be used).
>
> A patch for gPXE to send the ERROR packet is also being submitted to
> gPXE. Together they resolve slowness/hanging when booting pxegrub from
> qemu's internal TFTP server. The patch from Milan Plzik to return
> after sending OACK is also required for a complete fix.
>
> Signed-off-by: Thomas Horsten<address@hidden>
> Signed-off-by: Milan Plzik<address@hidden>
>    

Applied.  Thanks.

Regards,

Anthony Liguori
> ---
>   slirp/tftp.c |   23 +++++++++++++++++++++++
>   1 files changed, 23 insertions(+), 0 deletions(-)
>
> diff --git a/slirp/tftp.c b/slirp/tftp.c
> index db869fc..96c0e0c 100644
> --- a/slirp/tftp.c
> +++ b/slirp/tftp.c
> @@ -264,6 +264,12 @@ static void tftp_handle_rrq(Slirp *slirp, struct tftp_t 
> *tp, int pktlen)
>     size_t prefix_len;
>     char *req_fname;
>
> +  /* check if a session already exists and if so terminate it */
> +  s = tftp_session_find(slirp, tp);
> +  if (s>= 0) {
> +    tftp_session_terminate(&slirp->tftp_sessions[s]);
> +  }
> +
>     s = tftp_session_allocate(slirp, tp);
>
>     if (s<  0) {
> @@ -386,6 +392,19 @@ static void tftp_handle_ack(Slirp *slirp, struct tftp_t 
> *tp, int pktlen)
>     }
>   }
>
> +static void tftp_handle_error(Slirp *slirp, struct tftp_t *tp, int pktlen)
> +{
> +  int s;
> +
> +  s = tftp_session_find(slirp, tp);
> +
> +  if (s<  0) {
> +    return;
> +  }
> +
> +  tftp_session_terminate(&slirp->tftp_sessions[s]);
> +}
> +
>   void tftp_input(struct mbuf *m)
>   {
>     struct tftp_t *tp = (struct tftp_t *)m->m_data;
> @@ -398,5 +417,9 @@ void tftp_input(struct mbuf *m)
>     case TFTP_ACK:
>       tftp_handle_ack(m->slirp, tp, m->m_len);
>       break;
> +
> +  case TFTP_ERROR:
> +    tftp_handle_error(m->slirp, tp, m->m_len);
> +    break;
>     }
>   }
>