[PATCH] Skip logging for additional DNSSEC records from RFC4034 [BZ 14841]

[Siddhesh Poyarekar]

RFC 4034 specifies 3 more record types (RRSIG, NSEC, DNSKEY) that the
glibc resolver does not identify.  The resolver would log a message in
syslog if debugging is enabled in resolv.conf and RES_USE_DNSSEC is
set in the _res struct.  This was fine before since we did not set the
DO bit, but we do so now, so skip logging the message when we have
requested DNSSEC.

I have not added the identifiers to res_debug.c on purpose - it serves
no value other than adding an ABI event for libresolv since we're just
ignoring these records.

Tested on x86_64.

	[BZ #14841]
	* resolv/arpa/nameser.h (__ns_type): Add ns_t_rrsig, ns_t_nsec
	and ns_t_dnskey.
	* resolv/arpa/nameser_compat.h (T_RRSIG, T_NSEC, T_DNSKEY):
	Define.
	* resolv/gethnamaddr.c (getanswer): Use them to ignore DNSSEC
	records.  Skip logging if RES_USE_DNSSEC is set.
	* resolv/nss_dns/dns-host.c (getanswer_r): Likewise.
---
 resolv/arpa/nameser.h        |  3 +++
 resolv/arpa/nameser_compat.h |  3 +++
 resolv/gethnamaddr.c         | 21 +++++++++++++--------
 resolv/nss_dns/dns-host.c    | 19 +++++++++++++------
 4 files changed, 32 insertions(+), 14 deletions(-)

diff --git a/resolv/arpa/nameser.h b/resolv/arpa/nameser.h
index fb8513b..372d5cd 100644
--- a/resolv/arpa/nameser.h
+++ b/resolv/arpa/nameser.h
@@ -293,6 +293,9 @@ typedef enum __ns_type {
 	ns_t_sink = 40,		/*%< Kitchen sink (experimentatl) */
 	ns_t_opt = 41,		/*%< EDNS0 option (meta-RR) */
 	ns_t_apl = 42,		/*%< Address prefix list (RFC3123) */
+	ns_t_rrsig = 46,	/*%< DNSSEC RRset Signature (RFC4034) */
+	ns_t_nsec = 47,		/*%< DNSSEC Next-Secure Record (RFC4034)*/
+	ns_t_dnskey = 48,	/*%< DNSSEC key record (RFC4034) */
 	ns_t_tkey = 249,	/*%< Transaction key */
 	ns_t_tsig = 250,	/*%< Transaction signature. */
 	ns_t_ixfr = 251,	/*%< Incremental zone transfer. */
diff --git a/resolv/arpa/nameser_compat.h b/resolv/arpa/nameser_compat.h
index d59c9e4..284bff7 100644
--- a/resolv/arpa/nameser_compat.h
+++ b/resolv/arpa/nameser_compat.h
@@ -164,6 +164,9 @@ typedef struct {
 #define T_NAPTR		ns_t_naptr
 #define T_A6		ns_t_a6
 #define T_DNAME		ns_t_dname
+#define T_RRSIG		ns_t_rrsig
+#define T_NSEC		ns_t_nsec
+#define T_DNSKEY	ns_t_dnskey
 #define	T_TSIG		ns_t_tsig
 #define	T_IXFR		ns_t_ixfr
 #define T_AXFR		ns_t_axfr
diff --git a/resolv/gethnamaddr.c b/resolv/gethnamaddr.c
index a861a84..9e0c498 100644
--- a/resolv/gethnamaddr.c
+++ b/resolv/gethnamaddr.c
@@ -331,15 +331,20 @@ getanswer (const querybuf *answer, int anslen, const char *qname, int qtype)
 			buflen -= n;
 			continue;
 		}
-		if ((type == T_SIG) || (type == T_KEY) || (type == T_NXT)) {
-			/* We don't support DNSSEC yet.  For now, ignore
-			 * the record and send a low priority message
-			 * to syslog.
-			 */
-			syslog(LOG_DEBUG|LOG_AUTH,
+		if ((type == T_SIG) || (type == T_KEY) || (type == T_NXT)
+		    || (type == T_RRSIG) || (type == T_NSEC)
+		    || (type == T_DNSKEY)) {
+		        /* We don't support DNSSEC responses yet, but we do
+			 * allow setting the DO bit.  If the DNS server sent us
+			 * these records without us asking for it, ignore the
+			 * record and send a low priority message to syslog.
+		         */
+			if ((_res.options & RES_USE_DNSSEC) == 0) {
+				syslog(LOG_DEBUG|LOG_AUTH,
 	       "gethostby*.getanswer: asked for \"%s %s %s\", got type \"%s\"",
-			       qname, p_class(C_IN), p_type(qtype),
-			       p_type(type));
+					qname, p_class(C_IN), p_type(qtype),
+					p_type(type));
+			}
 			cp += n;
 			continue;
 		}
diff --git a/resolv/nss_dns/dns-host.c b/resolv/nss_dns/dns-host.c
index f715ab0..b10c94e 100644
--- a/resolv/nss_dns/dns-host.c
+++ b/resolv/nss_dns/dns-host.c
@@ -822,13 +822,20 @@ getanswer_r (const querybuf *answer, int anslen, const char *qname, int qtype,
 	}
       if (__builtin_expect (type == T_SIG, 0)
 	  || __builtin_expect (type == T_KEY, 0)
-	  || __builtin_expect (type == T_NXT, 0))
+	  || __builtin_expect (type == T_NXT, 0)
+	  || __builtin_expect (type == T_RRSIG, 0)
+	  || __builtin_expect (type == T_NSEC, 0)
+	  || __builtin_expect (type == T_DNSKEY, 0))
 	{
-	  /* We don't support DNSSEC yet.  For now, ignore the record
-	     and send a low priority message to syslog.  */
-	  syslog (LOG_DEBUG | LOG_AUTH,
-	       "gethostby*.getanswer: asked for \"%s %s %s\", got type \"%s\"",
-		  qname, p_class (C_IN), p_type(qtype), p_type (type));
+	  /* We don't support DNSSEC responses yet, but we do allow setting the
+	     DO bit.  If the DNS server sent us these records without us asking
+	     for it, ignore the record and send a low priority message to
+	     syslog.  */
+	  if ((_res.options & RES_USE_DNSSEC) == 0)
+	    syslog (LOG_DEBUG | LOG_AUTH,
+		    "gethostby*.getanswer: asked for \"%s %s %s\", "
+		    "got type \"%s\"",
+		    qname, p_class (C_IN), p_type(qtype), p_type (type));
 	  cp += n;
 	  continue;
 	}
-- 
2.1.0

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