Optimise sort_rrset for the case where the RR type no canonicalisation.

src/dnssec.c

@@ -335,6 +335,33 @@ static int sort_rrset(struct dns_header *header, size_t plen, u16 *rr_desc, int
 	    return rrsetidx; /* short packet */
 	  state2.end = state2.ip + rdlen2; 
 
+	  /* If the RR has no names in it then canonicalisation
+	     is the identity function and we can compare
+	     the RRs directly. If not we compare the 
+	     canonicalised RRs one byte at a time. */
+	  if (*rr_desc == (u16)-1)	  
+	    {
+	      int rdmin = rdlen1 > rdlen2 ? rdlen2 : rdlen1;
+	      int cmp = memcmp(state1.ip, state2.ip, rdmin);
+	      
+	      if (cmp > 0 || (cmp == 0 && rdlen1 > rdmin))
+		{
+		  unsigned char *tmp = rrset[i+1];
+		  rrset[i+1] = rrset[i];
+		  rrset[i] = tmp;
+		  swap = 1;
+		}
+	      else if (cmp == 0 && (rdlen1 == rdlen2))
+		{
+		  /* Two RRs are equal, remove one copy. RFC 4034, para 6.3 */
+		  for (j = i+1; j < rrsetidx-1; j++)
+		    rrset[j] = rrset[j+1];
+		  rrsetidx--;
+		  i--;
+		}
+	    }
+	  else
+	    /* Comparing canonicalised RRs, byte-at-a-time. */
 	    while (1)
 	      {
 		int ok1, ok2;