Re: [Qemu-devel] [v2] tftp: fake support for netascii protocol

[Stefan Hajnoczi]

On Sun, Nov 20, 2016 at 09:41:36AM +0100, Vincent Bernat wrote:
> From: Vincent Bernat <address@hidden>
> 
> Some network equipments are requesting a file using the netascii
> protocol and this is not configurable. Currently, qemu's tftpd only
> supports the octet protocol. This commit makes it accept the netascii
> protocol as well but do not perform the requested transformation (LF ->
> CR,LF) as it would be far more complex. The current implementation is
> good enough. A user has always the choice to preencode the served file
> correctly.
> 
> Signed-off-by: Vincent Bernat <address@hidden>
> ---
>  slirp/tftp.c | 11 ++++++++---
>  1 file changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/slirp/tftp.c b/slirp/tftp.c
> index c1859066ccb2..6907d5b92074 100644
> --- a/slirp/tftp.c
> +++ b/slirp/tftp.c
> @@ -26,6 +26,7 @@
>  #include "slirp.h"
>  #include "qemu-common.h"
>  #include "qemu/cutils.h"
> +#include "qemu/log.h"
>  
>  static inline int tftp_session_in_use(struct tftp_session *spt)
>  {
> @@ -326,13 +327,17 @@ static void tftp_handle_rrq(Slirp *slirp, struct 
> sockaddr_storage *srcsas,
>      return;
>    }
>  
> -  if (strcasecmp(&tp->x.tp_buf[k], "octet") != 0) {
> +  if (strcasecmp(&tp->x.tp_buf[k], "octet") == 0) {
> +      k += 6;
> +  } else if (strcasecmp(&tp->x.tp_buf[k], "netascii") == 0) {
> +      qemu_log_mask(LOG_UNIMP, "tftp: netascii protocol not implemented, "
> +                    "no CR-LF conversion\n");
> +      k += 9;
> +  } else {

This is an RFC violation.  I don't think it's suitable for upstream QEMU.

The commit description says it would be "far more complex" to implement
netascii.  Is the LF -> CR LF and CR -> CR NUL transformation so hard?

CCing H. Peter Anvin who has TFTP expertise in case I'm missing
something.

Stefan

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