[Dnsmasq-discuss] [PATCH] dnsmasq: compile time option NO_ID

[Kevin Darbyshire-Bryant]

Some consider it good practice to obscure software version numbers to
clients.  Compiling with -DNO_ID removes the *.bind info structure.
This includes: version, author, copyright, cachesize, cache insertions,
evictions, misses & hits, auth & servers.

Signed-off-by: Kevin Darbyshire-Bryant <kevin at darbyshire-bryant.me.uk>
---
 src/cache.c   | 2 ++
 src/config.h  | 5 +++++
 src/dnsmasq.h | 4 ++++
 src/option.c  | 8 ++++++--
 src/rfc1035.c | 3 ++-
 5 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/src/cache.c b/src/cache.c
index 4ecd535..eca56c8 100644
--- a/src/cache.c
+++ b/src/cache.c
@@ -1290,6 +1290,7 @@ void cache_add_dhcp_entry(char *host_name, int prot,
 }
 #endif
 
+#ifndef NO_ID
 int cache_make_stat(struct txt_record *t)
 { 
   static char *buff = NULL;
@@ -1385,6 +1386,7 @@ int cache_make_stat(struct txt_record *t)
   *buff = len;
   return 1;
 }
+#endif
 
 /* There can be names in the cache containing control chars, don't 
    mess up logging or open security holes. */
diff --git a/src/config.h b/src/config.h
index 80a50e1..7ca7d7f 100644
--- a/src/config.h
+++ b/src/config.h
@@ -120,6 +120,8 @@ HAVE_LOOP
 HAVE_INOTIFY
    use the Linux inotify facility to efficiently re-read configuration files.
 
+NO_ID
+   Don't report *.bind CHAOS info to clients.
 NO_IPV6
 NO_TFTP
 NO_DHCP
@@ -434,6 +436,9 @@ static char *compile_opts =
 "no-"
 #endif
 "DNSSEC "
+#ifdef NO_ID
+"no-ID "
+#endif
 #ifndef HAVE_LOOP
 "no-"
 #endif
diff --git a/src/dnsmasq.h b/src/dnsmasq.h
index f239ce5..4b55bb5 100644
--- a/src/dnsmasq.h
+++ b/src/dnsmasq.h
@@ -286,6 +286,7 @@ struct naptr {
   struct naptr *next;
 };
 
+#ifndef NO_ID
 #define TXT_STAT_CACHESIZE     1
 #define TXT_STAT_INSERTS       2
 #define TXT_STAT_EVICTIONS     3
@@ -293,6 +294,7 @@ struct naptr {
 #define TXT_STAT_HITS          5
 #define TXT_STAT_AUTH          6
 #define TXT_STAT_SERVERS       7
+#endif
 
 struct txt_record {
   char *name;
@@ -1081,7 +1083,9 @@ void cache_add_dhcp_entry(char *host_name, int prot, struct all_addr *host_addre
 struct in_addr a_record_from_hosts(char *name, time_t now);
 void cache_unhash_dhcp(void);
 void dump_cache(time_t now);
+#ifndef NO_ID
 int cache_make_stat(struct txt_record *t);
+#endif
 char *cache_get_name(struct crec *crecp);
 char *cache_get_cname_target(struct crec *crecp);
 struct crec *cache_enumerate(int init);
diff --git a/src/option.c b/src/option.c
index d811ed3..d0d9509 100644
--- a/src/option.c
+++ b/src/option.c
@@ -657,7 +657,8 @@ static int atoi_check8(char *a, int *res)
   return 1;
 }
 #endif
-	
+
+#ifndef NO_ID
 static void add_txt(char *name, char *txt, int stat)
 {
   struct txt_record *r = opt_malloc(sizeof(struct txt_record));
@@ -670,13 +671,14 @@ static void add_txt(char *name, char *txt, int stat)
       *(r->txt) = len;
       memcpy((r->txt)+1, txt, len);
     }
-  
+
   r->stat = stat;
   r->name = opt_string_alloc(name);
   r->next = daemon->txt;
   daemon->txt = r;
   r->class = C_CHAOS;
 }
+#endif
 
 static void do_usage(void)
 {
@@ -4532,6 +4534,7 @@ void read_opts(int argc, char **argv, char *compile_opts)
   daemon->soa_expiry = SOA_EXPIRY;
   daemon->max_port = MAX_PORT;
 
+#ifndef NO_ID
   add_txt("version.bind", "dnsmasq-" VERSION, 0 );
   add_txt("authors.bind", "Simon Kelley", 0);
   add_txt("copyright.bind", COPYRIGHT, 0);
@@ -4544,6 +4547,7 @@ void read_opts(int argc, char **argv, char *compile_opts)
   add_txt("auth.bind", NULL, TXT_STAT_AUTH);
 #endif
   add_txt("servers.bind", NULL, TXT_STAT_SERVERS);
+#endif
 
   while (1) 
     {
diff --git a/src/rfc1035.c b/src/rfc1035.c
index 9e730a9..fbcb564 100644
--- a/src/rfc1035.c
+++ b/src/rfc1035.c
@@ -1269,6 +1269,7 @@ size_t answer_request(struct dns_header *header, char *limit, size_t qlen,
 		      unsigned long ttl = daemon->local_ttl;
 		      int ok = 1;
 		      log_query(F_CONFIG | F_RRNAME, name, NULL, "<TXT>");
+#ifndef NO_ID
 		      /* Dynamically generate stat record */
 		      if (t->stat != 0)
 			{
@@ -1276,7 +1277,7 @@ size_t answer_request(struct dns_header *header, char *limit, size_t qlen,
 			  if (!cache_make_stat(t))
 			    ok = 0;
 			}
-		      
+#endif
 		      if (ok && add_resource_record(header, limit, &trunc, nameoffset, &ansp, 
 						    ttl, NULL,
 						    T_TXT, t->class, "t", t->len, t->txt))
-- 
2.7.4