Handle caching SOA for negative PTR queries.

Also deal with the fact that a root SOA is a thing.

src/cache.c

@@ -802,9 +802,6 @@ void cache_end_insert(void)
 	      read_write(daemon->pipe_to_parent, (unsigned char *)name, m, 0);
 	      read_write(daemon->pipe_to_parent, (unsigned char *)&new_chain->ttd, sizeof(new_chain->ttd), 0);
 	      read_write(daemon->pipe_to_parent, (unsigned  char *)&flags, sizeof(flags), 0);
-
-	      if (flags & (F_IPV4 | F_IPV6 | F_DNSKEY | F_DS | F_RR))
-		{
 	      read_write(daemon->pipe_to_parent, (unsigned char *)&new_chain->addr, sizeof(new_chain->addr), 0);
 	      
 	      if (flags & F_RR)
@@ -829,7 +826,6 @@ void cache_end_insert(void)
 #endif
 	    }
 	}
-	}
       
       new_chain = tmp;
     }
@@ -871,7 +867,8 @@ int cache_recv_insert(time_t now, int fd)
 
       if (!read_write(fd, (unsigned char *)daemon->namebuff, m, 1) ||
 	  !read_write(fd, (unsigned char *)&ttd, sizeof(ttd), 1) ||
-	  !read_write(fd, (unsigned char *)&flags, sizeof(flags), 1))
+	  !read_write(fd, (unsigned char *)&flags, sizeof(flags), 1) ||
+	  !read_write(fd, (unsigned char *)&addr, sizeof(addr), 1))
 	return 0;
 
       daemon->namebuff[m] = 0;
@@ -902,11 +899,6 @@ int cache_recv_insert(time_t now, int fd)
 	{
 	  unsigned short class = C_IN;
 
-	  if (flags & (F_IPV4 | F_IPV6 | F_DNSKEY | F_DS | F_RR))
-	    {
-	      if (!read_write(fd, (unsigned char *)&addr, sizeof(addr), 1))
-		return 0;
-	      
 	  if ((flags & F_RR) && !(flags & F_NEG) && (flags & F_KEYTAG)
 	      && !(addr.rrblock.rrdata = blockdata_read(fd, addr.rrblock.datalen)))
 	    return 0;
@@ -924,8 +916,6 @@ int cache_recv_insert(time_t now, int fd)
 		return 0;
 	    }
 #endif
-	    }
-	  
 	  crecp = really_insert(daemon->namebuff, &addr, class, now, ttl, flags);
 	}
     }
@@ -1809,8 +1799,18 @@ static void dump_cache_entry(struct crec *cache, time_t now)
   p = buff;
   
   *a = 0;
-  if (strlen(n) == 0 && !(cache->flags & F_REVERSE))
+
+  if (cache->flags & F_REVERSE)
+    {
+      if ((cache->flags & F_NEG))
+	n = "";
+    }
+  else
+    {
+      if (strlen(n) == 0)
 	n = "<Root>";
+    }
+  
   p += sprintf(p, "%-30.30s ", sanitise(n));
   if ((cache->flags & F_CNAME) && !is_outdated_cname_pointer(cache))
     a = sanitise(cache_get_cname_target(cache));

src/rfc1035.c

@@ -454,7 +454,7 @@ int do_doctor(struct dns_header *header, size_t qlen)
    Cache said SOA and return the difference in length between name and the name of the 
    SOA RR so we can look it up again.
 */
-static int find_soa(struct dns_header *header, size_t qlen, char *name, int *substring, int no_cache, time_t now)
+static int find_soa(struct dns_header *header, size_t qlen, char *name, int *substring, unsigned long *ttlp, int no_cache, time_t now)
 {
   unsigned char *p, *psave;
   int qtype, qclass, rdlen;
@@ -473,6 +473,9 @@ static int find_soa(struct dns_header *header, size_t qlen, char *name, int *sub
   if (substring)
     *substring = name_len;
 
+  if (ttlp)
+    *ttlp = daemon->neg_ttl;
+  
   for (i = 0; i < ntohs(header->nscount); i++)
     {
       if (!extract_name(header, qlen, &p, daemon->workspacename, 1, 0))
@@ -571,7 +574,10 @@ static int find_soa(struct dns_header *header, size_t qlen, char *name, int *sub
 	      if (substring)
 		*substring = prefix;
 	      
-	      return minttl;
+	      if (ttlp)
+		*ttlp = minttl;
+
+	      return 1;
 	    }
 	}
 
@@ -581,7 +587,7 @@ static int find_soa(struct dns_header *header, size_t qlen, char *name, int *sub
 	return 0; /* bad packet */
     }
   
-  return daemon->neg_ttl;
+  return 0;
 }
 
 /* Print TXT reply to log */
@@ -747,14 +753,16 @@ int extract_addresses(struct dns_header *header, size_t qlen, char *name, time_t
       
       if (!found && !option_bool(OPT_NO_NEG))
 	{
-	  /* don't cache SOAs for negative PTR records */
+	  /* For reverse records, we use the name field to store the SOA name. */
-	  ttl = find_soa(header, qlen, name, NULL, 1, now);
+	  int substring, have_soa = find_soa(header, qlen, name, &substring, &ttl, no_cache_dnssec, now);
 	  
 	  flags |= F_NEG | (secure ?  F_DNSSECOK : 0);
 	  if (name_encoding && ttl)
 	    {
 	      flags |= F_REVERSE | name_encoding;
-	      cache_insert(NULL, &addr, C_IN, now, ttl, flags);
+	      if (!have_soa)
+		flags |= F_NO_RR; /* Marks no SOA found. */
+	      cache_insert(name + substring, &addr, C_IN, now, ttl, flags);
 	    }
 	  
 	  log_query(flags | F_UPSTREAM, name, &addr, NULL, 0);
@@ -1038,7 +1046,7 @@ int extract_addresses(struct dns_header *header, size_t qlen, char *name, time_t
       
       if (!found && (qtype != T_ANY || (flags & F_NXDOMAIN)))
 	{
-	  int substring;
+	  int substring, have_soa;
 
 	  if (flags & F_NXDOMAIN)
 	    {
@@ -1050,15 +1058,23 @@ int extract_addresses(struct dns_header *header, size_t qlen, char *name, time_t
 	  
 	  log_query(F_UPSTREAM | F_FORWARD | F_NEG | flags | (secure ? F_DNSSECOK : 0), name, NULL, NULL, 0);
 	  
+	  if (insert && !option_bool(OPT_NO_NEG))
+	    {
+	      int have_soa = find_soa(header, qlen, name, &substring, &ttl, no_cache_dnssec, now);
+	      
 	      /* If there's no SOA to get the TTL from, but there is a CNAME 
 		 pointing at this, inherit its TTL */
-	  if (insert && !option_bool(OPT_NO_NEG) && ((ttl = find_soa(header, qlen, name, &substring, no_cache_dnssec, now)) || cpp))
+	      if (ttl || cpp)
 		{
+		  if (!ttl)
+		    ttl = cttl;
+		  
 		  addr.rrdata.datalen = substring;
 		  addr.rrdata.rrtype = qtype;
 		  
-	      if (ttl == 0)
+		  if (!have_soa)
-		ttl = cttl;
+		    flags |= F_NO_RR; /* Marks no SOA found. */
+		}
 	      
 	      newc = cache_insert(name, &addr, C_IN, now, ttl, F_FORWARD | F_NEG | flags | (secure ? F_DNSSECOK : 0));	
 	      if (newc && cpp)
@@ -1627,6 +1643,9 @@ size_t answer_request(struct dns_header *header, char *limit, size_t qlen,
 	    stale_flag = F_STALE;
 	  }
 	
+	if (crecp->flags & F_NEG)
+	  soa_lookup = crecp;
+	  
 	if (crecp->flags & F_NXDOMAIN)
 	  {
 	    if (qtype == T_CNAME)
@@ -1831,6 +1850,7 @@ size_t answer_request(struct dns_header *header, char *limit, size_t qlen,
 			  if (crecp->flags & F_NXDOMAIN)
 			    nxdomain = 1;
 			  log_query(stale_flag | (crecp->flags & ~F_FORWARD), name, &addr, NULL, 0);
+			  soa_lookup = crecp;
 			}
 		      else
 			{
@@ -2236,21 +2256,31 @@ size_t answer_request(struct dns_header *header, char *limit, size_t qlen,
   if (!ans)
     return 0; /* failed to answer a question */
 
-  if (soa_lookup)
-    {
   /* We found a negative record. See if we have an SOA record to 
-	 return in the AUTH section. */
+     return in the AUTH section. 
-      char *rrdata;
+     
-      int substring = soa_lookup->addr.rrdata.datalen;
+     For FORWARD NEG records, the addr.rrdata.datalen field of the othewise
+     empty addr is used to held an offset in to the name which yields the SOA
+     name. For REVERSE NEG records, the otherwise empty name field holds the
+     SOA name. If soa_name has zero length, then no SOA is known. soa_lookup
+     MUST be a neg record here.
+     
+     If the F_NO_RR flag is set, there was no SOA record supplied with the RR.  */
+  if (soa_lookup && !(soa_lookup->flags & F_NO_RR))
+    {
+      char *soa_name = soa_lookup->flags & F_REVERSE ? cache_get_name(soa_lookup) : name + soa_lookup->addr.rrdata.datalen;
+      
       crecp = NULL;
-      while ((crecp = cache_find_by_name(crecp, name + substring, now, F_RR)))
+      while ((crecp = cache_find_by_name(crecp, soa_name, now, F_RR)))
 	if (crecp->addr.rrblock.rrtype == T_SOA)
 	  {
+	    char *rrdata;
+	    
 	    if (!(crecp->flags & F_NEG) &&
 		(rrdata = blockdata_retrieve(crecp->addr.rrblock.rrdata, crecp->addr.rrblock.datalen, NULL)) &&
 		add_resource_record(header, limit, &trunc, 0, &ansp, 
 				    crec_ttl(crecp, now), NULL, T_SOA, C_IN, "t",
-				    name + substring, crecp->addr.rrblock.datalen, rrdata))
+				    soa_name, crecp->addr.rrblock.datalen, rrdata))
 	      {
 		nscount++;