[PATCH v2 1/2] support: Change non-address output format of support_format_dns_packet

[Carlos O'Donell]

On 6/7/22 16:29, Florian Weimer via Libc-alpha wrote:
> It makes sense to include the owner name (LHS) and record type in the
> output, so that they can be checked for correctness.

LGTM.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>

> ---
> v2: New patch.
>  support/support_format_dns_packet.c     | 22 +++++++++++++++-------
>  support/tst-support_format_dns_packet.c |  4 ++--
>  2 files changed, 17 insertions(+), 9 deletions(-)
> 
> diff --git a/support/support_format_dns_packet.c b/support/support_format_dns_packet.c
> index e8b3c125e3..14344bc1bf 100644
> --- a/support/support_format_dns_packet.c
> +++ b/support/support_format_dns_packet.c
> @@ -90,6 +90,17 @@ extract_name (struct in_buffer full, struct in_buffer *in, struct dname *value)
>    return true;
>  }
>  
> +static void
> +extract_name_data (struct in_buffer full, struct in_buffer *rdata,
> +                   const struct dname *owner, const char *typename, FILE *out)
> +{
> +  struct dname name;
> +  if (extract_name (full, rdata, &name))

OK. extract_name() is just above which uses dn_expand() API.

> +    fprintf (out, "data: %s %s %s\n", owner->name, typename, name.name);
> +  else
> +    fprintf (out, "error: malformed CNAME/PTR record\n");
> +}
> +
>  char *
>  support_format_dns_packet (const unsigned char *buffer, size_t length)
>  {
> @@ -195,14 +206,11 @@ support_format_dns_packet (const unsigned char *buffer, size_t length)
>            }
>            break;
>          case T_CNAME:
> +          extract_name_data (full, &rdata, &rname, "CNAME", mem.out);
> +          break;

OK. The split here allows you to distinguish in the logs if it was a CNAME or PTR that failed.
This allows checking for exact CNAME or PTR message in the logs.

>          case T_PTR:
> -          {
> -            struct dname name;
> -            if (extract_name (full, &rdata, &name))
> -              fprintf (mem.out, "name: %s\n", name.name);
> -            else
> -              fprintf (mem.out, "error: malformed CNAME/PTR record\n");
> -          }
> +          extract_name_data (full, &rdata, &rname, "PTR", mem.out);
> +          break;
>          }
>      }
>  
> diff --git a/support/tst-support_format_dns_packet.c b/support/tst-support_format_dns_packet.c
> index cb7ff53b87..9839aa767e 100644
> --- a/support/tst-support_format_dns_packet.c
> +++ b/support/tst-support_format_dns_packet.c
> @@ -85,8 +85,8 @@ test_multiple_cnames (void)
>      "\xc0\x00\x02\x01";
>    check_packet (packet, sizeof (packet) - 1, __func__,
>                  "name: www.example\n"
> -                "name: www1.example\n"
> -                "name: www2.example\n"
> +                "data: www.example CNAME www1.example\n"
> +                "data: www1.example CNAME www2.example\n"

OK. Data adjusted.

>                  "address: 192.0.2.1\n");
>  }
>  
> 
> base-commit: 5082a287d5e9a1f9cb98b7c982a708a3684f1d5c


-- 
Cheers,
Carlos.