[PATCH v2 3/8] resolv: Fix ns_sprintrrf formatting of class, type values (bug 34289)

[Carlos O'Donell]

On 6/16/26 12:31 PM, Florian Weimer wrote:
> The p_class and p_type results could overwrite each other if both
> were unknown.  Format unknown values with CLASS and TYPE prefixes,
> as in RFC 3597.  Handle A6 separately because it cannot be added
> to __p_type_syms for ABI reasons.

LGTM.

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

> ---
>   resolv/ns_print.c | 38 +++++++++++++++++++++++++++++++++-----
>   1 file changed, 33 insertions(+), 5 deletions(-)
> 
> diff --git a/resolv/ns_print.c b/resolv/ns_print.c
> index cef2212fd2..e75c39eaa8 100644
> --- a/resolv/ns_print.c
> +++ b/resolv/ns_print.c
> @@ -78,6 +78,24 @@ ns_sprintrr(const ns_msg *handle, const ns_rr *rr,
>   }
>   libresolv_hidden_def (ns_sprintrr)
>   
> +/* Writes the class/type symbol NUMBER to *BUF, using the name from
> +   *SYMS if possible.  If NUMBER is not found in *SYMS, print the
> +   number with PREFIX.  */
> +static int
> +addsym (const struct res_sym *syms, int number, const char *prefix,
> +	char **buf, size_t *buflen)
> +{
> +  for (; syms->name != NULL; syms++)
> +    if (number == syms->number)
> +      {
> +	T (addstr (" ", 1, buf, buflen));
> +	return addstr (syms->name, strlen (syms->name), buf, buflen);
> +      }
> +  char tmp[20];
> +  int len = snprintf (tmp, sizeof (tmp), " %s%d", prefix, number);
> +  return addstr (tmp, len, buf, buflen);

OK.

> +}
> +
>   /*%
>    *	Convert the fields of an RR into presentation format.
>    *
> @@ -128,11 +146,21 @@ ns_sprintrrf(const u_char *msg, size_t msglen,
>   	/*
>   	 * TTL, Class, Type.
>   	 */
> -	T(x = ns_format_ttl(ttl, buf, buflen));
> -	addlen(x, &buf, &buflen);
> -	len = SPRINTF((tmp, " %s %s", p_class(class), p_type(type)));
> -	T(addstr(tmp, len, &buf, &buflen));
> -	T(spaced = addtab(x + len, 16, spaced, &buf, &buflen));
> +	{
> +	  char *start = buf;
> +
> +	  T (x = ns_format_ttl (ttl, buf, buflen));
> +	  addlen (x, &buf, &buflen);
> +	  T (addsym (__p_class_syms, class, "CLASS", &buf, &buflen));

OK. Use __p_class_syms directly.

> +	  if (type == ns_t_a6)
> +	    /* A6 is not part of __p_type_syms, which is exported.
> +	       Adding A6 there would change its size.  Handle it here.  */
> +	    T (addstr (" A6", 3, &buf, &buflen));
> +	  else
> +	    T (addsym (__p_type_syms, type, "TYPE", &buf, &buflen));

OK. Use __p_type_syms directly.

> +
> +	  T (spaced = addtab(buf - start, 16, spaced, &buf, &buflen));
> +	}
>   
>   	/*
>   	 * RData.


-- 
Cheers,
Carlos.