From 1fd56c0e333e1e800221581b6da4de79b381195e Mon Sep 17 00:00:00 2001
From: Simon Kelley <simon@thekelleys.org.uk>
Date: Wed, 30 Oct 2019 12:58:28 +0000
Subject: [PATCH] Tidy up CNAME representaion.

Use an explicit discriminator for the target union.
---
 src/cache.c   | 22 ++++++++++------------
 src/dnsmasq.h |  7 ++-----
 src/rfc1035.c |  7 +++----
 3 files changed, 15 insertions(+), 21 deletions(-)

diff --git a/src/cache.c b/src/cache.c
index 37f0a89..6168073 100644
--- a/src/cache.c
+++ b/src/cache.c
@@ -276,10 +276,10 @@ char *cache_get_name(struct crec *crecp)
 
 char *cache_get_cname_target(struct crec *crecp)
 {
-  if (crecp->addr.cname.uid != SRC_PTR)
+  if (crecp->addr.cname.is_name_ptr)
+     return crecp->addr.cname.target.name;
+  else
     return cache_get_name(crecp->addr.cname.target.cache);
-
-  return crecp->addr.cname.target.name;
 }
 
 
@@ -309,7 +309,7 @@ struct crec *cache_enumerate(int init)
 
 static int is_outdated_cname_pointer(struct crec *crecp)
 {
-  if (!(crecp->flags & F_CNAME) || crecp->addr.cname.uid == SRC_PTR)
+  if (!(crecp->flags & F_CNAME) || crecp->addr.cname.is_name_ptr)
     return 0;
   
   /* NB. record may be reused as DS or DNSKEY, where uid is 
@@ -776,13 +776,11 @@ int cache_recv_insert(time_t now, int fd)
 	     the order reversal on the new_chain. */
 	  if (newc)
 	    {
-	      if (!crecp)
-		{
-		  newc->addr.cname.target.cache = NULL;
-		  /* anything other than zero, to avoid being mistaken for CNAME to interface-name */ 
-		  newc->addr.cname.uid = 1; 
-		}
-	      else
+	       newc->addr.cname.is_name_ptr = 0;
+	       
+	       if (!crecp)
+		 newc->addr.cname.target.cache = NULL;
+	       else
 		{
 		  next_uid(crecp);
 		  newc->addr.cname.target.cache = crecp;
@@ -1226,7 +1224,7 @@ void cache_reload(void)
 	cache->ttd = a->ttl;
 	cache->name.namep = a->alias;
 	cache->addr.cname.target.name = a->target;
-	cache->addr.cname.uid = SRC_PTR;
+	cache->addr.cname.is_name_ptr = 1;
 	cache->uid = UID_NONE;
 	cache_hash(cache);
 	make_non_terminals(cache);
diff --git a/src/dnsmasq.h b/src/dnsmasq.h
index c81e00a..78f808d 100644
--- a/src/dnsmasq.h
+++ b/src/dnsmasq.h
@@ -289,7 +289,8 @@ union all_addr {
       struct crec *cache;
       char *name;
     } target;
-    unsigned int uid; /* 0 if union is char * */
+    unsigned int uid;
+    int is_name_ptr;  /* disciminates target union */
   } cname;
   struct {
     struct blockdata *keydata;
@@ -483,10 +484,6 @@ struct crec {
 
 #define UID_NONE      0
 /* Values of uid in crecs with F_CONFIG bit set. */
-/* cname to uid SRC_PTR are to locally-configured CNAME
-   so use UID_NONE for that to 
-   eliminate clashes with any other uid */
-#define SRC_PTR UID_NONE
 #define SRC_CONFIG    1
 #define SRC_HOSTS     2
 #define SRC_AH        3
diff --git a/src/rfc1035.c b/src/rfc1035.c
index 6c6f66d..502744b 100644
--- a/src/rfc1035.c
+++ b/src/rfc1035.c
@@ -784,12 +784,11 @@ int extract_addresses(struct dns_header *header, size_t qlen, char *name, time_t
 		    {
 		      if (!cname_count--)
 			return 0; /* looped CNAMES */
-		      newc = cache_insert(name, NULL, C_IN, now, attl, F_CNAME | F_FORWARD | secflag);
-		      if (newc)
+
+		      if ((newc = cache_insert(name, NULL, C_IN, now, attl, F_CNAME | F_FORWARD | secflag)))
 			{
 			  newc->addr.cname.target.cache = NULL;
-			  /* anything other than zero, to avoid being mistaken for a local CNAME */ 
-			  newc->addr.cname.uid = 1; 
+			  newc->addr.cname.is_name_ptr = 0; 
 			  if (cpp)
 			    {
 			      next_uid(newc);