Decode BGP Shutdown Communication messages (RFC 8203)

[Job Snijders]

bump? :-)

On Fri, Jul 28, 2017 at 12:26:59PM +0200, Job Snijders wrote:
> Spin #2
> 
> ---
>  proto/bgp/bgp.c     | 12 +++++++++
>  proto/bgp/bgp.h     |  2 ++
>  proto/bgp/packets.c | 73 ++++++++++++++++++++++++++++++++++-------------------
>  3 files changed, 61 insertions(+), 26 deletions(-)
> 
> diff --git a/proto/bgp/bgp.c b/proto/bgp/bgp.c
> index f706e76..2a89c00 100644
> --- a/proto/bgp/bgp.c
> +++ b/proto/bgp/bgp.c
> @@ -1487,6 +1487,15 @@ bgp_last_errmsg(struct bgp_proto *p)
>  }
>  
>  static const char *
> +bgp_last_shutmsg(struct bgp_proto *p)
> +{
> +    if (p->last_received_shutmsg)
> +      return(p->last_received_shutmsg);
> +    else
> +      return(NULL);
> +}
> +
> +static const char *
>  bgp_state_dsc(struct bgp_proto *p)
>  {
>    if (p->p.proto_state == PS_DOWN)
> @@ -1580,7 +1589,10 @@ bgp_show_proto_info(struct proto *P)
>      {
>        const char *err1 = bgp_err_classes[p->last_error_class];
>        const char *err2 = bgp_last_errmsg(p);
> +      const char *msg  = bgp_last_shutmsg(p);
>        cli_msg(-1006, "    Last error:       %s%s", err1, err2);
> +      if (msg)
> +        cli_msg(-1006, "    Message:          \"%s\"", msg);
>      }
>  }
>  
> diff --git a/proto/bgp/bgp.h b/proto/bgp/bgp.h
> index e47a0eb..d958716 100644
> --- a/proto/bgp/bgp.h
> +++ b/proto/bgp/bgp.h
> @@ -157,6 +157,8 @@ struct bgp_proto {
>    u8 last_error_class; 			/* Error class of last error */
>    u32 last_error_code;			/* Error code of last error. BGP protocol errors
>  					   are encoded as (bgp_err_code << 16 | bgp_err_subcode) */
> +  byte last_received_shutmsg[129];		/* RFC 8203 */
> +
>  #ifdef IPV6
>    byte *mp_reach_start, *mp_unreach_start; /* Multiprotocol BGP attribute notes */
>    unsigned mp_reach_len, mp_unreach_len;
> diff --git a/proto/bgp/packets.c b/proto/bgp/packets.c
> index ab87bdc..a44f264 100644
> --- a/proto/bgp/packets.c
> +++ b/proto/bgp/packets.c
> @@ -1460,9 +1460,9 @@ static struct {
>    { 5, 3, "Unexpected message in Established state" },
>    { 6, 0, "Cease" }, /* Subcodes are according to [RFC4486] */
>    { 6, 1, "Maximum number of prefixes reached" },
> -  { 6, 2, "Administrative shutdown" },
> +  { 6, 2, "Administrative shutdown" }, /* RFC 8203 can follow */
>    { 6, 3, "Peer de-configured" },
> -  { 6, 4, "Administrative reset" },
> +  { 6, 4, "Administrative reset" }, /* RFC 8203 can follow */
>    { 6, 5, "Connection rejected" },
>    { 6, 6, "Other configuration change" },
>    { 6, 7, "Connection collision resolution" },
> @@ -1497,35 +1497,56 @@ bgp_error_dsc(unsigned code, unsigned subcode)
>  void
>  bgp_log_error(struct bgp_proto *p, u8 class, char *msg, unsigned code, unsigned subcode, byte *data, unsigned len)
>  {
> -  const byte *name;
> -  byte *t, argbuf[36];
> -  unsigned i;
> +    const byte *name;
> +    byte *t, argbuf[256];
> +    unsigned i;
> +    unsigned shutdown_comm_length;
>  
> -  /* Don't report Cease messages generated by myself */
> -  if (code == 6 && class == BE_BGP_TX)
> -    return;
> +    /* Don't report Cease messages generated by myself */
> +    if (code == 6 && class == BE_BGP_TX)
> +        return;
> +
> +    name = bgp_error_dsc(code, subcode);
> +    t = argbuf;
> +    memset(p->last_received_shutmsg, 0, 128 + 1); // clear old RFC 8203 messages
>  
> -  name = bgp_error_dsc(code, subcode);
> -  t = argbuf;
> -  if (len)
> +    if (len)
>      {
> -      *t++ = ':';
> -      *t++ = ' ';
> +        *t++ = ':';
> +        *t++ = ' ';
>  
> -      if ((code == 2) && (subcode == 2) && ((len == 2) || (len == 4)))
> -	{
> -	  /* Bad peer AS - we would like to print the AS */
> -	  t += bsprintf(t, "%d", (len == 2) ? get_u16(data) : get_u32(data));
> -	  goto done;
> -	}
> -      if (len > 16)
> -	len = 16;
> -      for (i=0; i<len; i++)
> -	t += bsprintf(t, "%02x", data[i]);
> +        if ((code == 2) && (subcode == 2) && ((len == 2) || (len == 4)))
> +        {
> +            /* Bad peer AS - we would like to print the AS */
> +            t += bsprintf(t, "%d", (len == 2) ? get_u16(data) : get_u32(data));
> +            goto done;
> +        }
> +        /* RFC 8203 */
> +        if ((code == 6) && ((subcode == 2 || subcode == 4)) && (len <= 129))
> +        {
> +            shutdown_comm_length = data[0];
> +            if ((shutdown_comm_length <= 128) && (len == shutdown_comm_length + 1))
> +            {
> +                t += bsprintf(t, "\"");
> +                for (i=1; i<len; i++)
> +                    t += bsprintf(t, "%c", data[i]);
> +                t += bsprintf(t, "\"");
> +                memcpy(p->last_received_shutmsg, data + 1, shutdown_comm_length);
> +                goto done;
> +            }
> +        }
> +        else
> +        {
> +            if (len > 16)
> +                len = 16;
> +            for (i=0; i<len; i++)
> +                t += bsprintf(t, "%02x", data[i]);
> +        }
>      }
> - done:
> -  *t = 0;
> -  log(L_REMOTE "%s: %s: %s%s", p->p.name, msg, name, argbuf);
> +
> +  done:
> +    *t = 0;
> +    log(L_REMOTE "%s: %s: %s%s", p->p.name, msg, name, argbuf);
>  }
>  
>  static void