Add --max-cache-ttl option.

CHANGELOG

@@ -25,6 +25,9 @@ version 2.64
 	    Fix build with later Lua libraries. Thansk to Cristian
 	    Rodriguez for the patch.
 
+	    Add --max-cache-ttl option. Thanks to Dennis Kaarsemaker
+	    for the patch.
+
 	    
 version 2.63
             Do duplicate dhcp-host address check in --test mode.

man/dnsmasq.8

@@ -71,6 +71,9 @@ maximum TTL will be given to clients instead of the true TTL value if it is
 lower. The true TTL value is however kept in the cache to avoid flooding 
 the upstream DNS servers.
 .TP
+.B --max-cache-ttl=<time>
+Set a maximum TTL value for entries in the cache.
+.TP
 .B \-k, --keep-in-foreground
 Do not go into the background at startup but otherwise run as
 normal. This is intended for use when dnsmasq is run under daemontools

src/cache.c

@@ -371,6 +371,9 @@ struct crec *cache_insert(char *name, struct all_addr *addr,
   int freed_all = flags & F_REVERSE;
   int free_avail = 0;
 
+  if(daemon->max_cache_ttl < ttl)
+    ttl = daemon->max_cache_ttl;
+
   /* Don't log keys */
   if (flags & (F_IPV4 | F_IPV6))
     log_query(flags | F_UPSTREAM, name, addr, NULL);

src/dnsmasq.h

@@ -751,7 +751,7 @@ extern struct daemon {
   int max_logs;  /* queue limit */
   int cachesize, ftabsize;
   int port, query_port, min_port;
-  unsigned long local_ttl, neg_ttl, max_ttl;
+  unsigned long local_ttl, neg_ttl, max_ttl, max_cache_ttl;
   struct hostsfile *addn_hosts;
   struct dhcp_context *dhcp, *dhcp6, *ra_contexts;
   struct dhcp_config *dhcp_conf;

src/option.c

@@ -120,6 +120,7 @@ struct myoption {
 #define LOPT_TFTP_LC   309
 #define LOPT_RR        310
 #define LOPT_CLVERBIND 311
+#define LOPT_MAXCTTL   312
 
 #ifdef HAVE_GETOPT_LONG
 static const struct option opts[] =  
@@ -223,6 +224,7 @@ static const struct myoption opts[] =
     { "dhcp-broadcast", 2, 0, LOPT_BROADCAST },
     { "neg-ttl", 1, 0, LOPT_NEGTTL },
     { "max-ttl", 1, 0, LOPT_MAXTTL },
+    { "max-cache-ttl", 1, 0, LOPT_MAXCTTL },
     { "dhcp-alternate-port", 2, 0, LOPT_ALTPORT },
     { "dhcp-scriptuser", 1, 0, LOPT_SCRIPTUSR },
     { "min-port", 1, 0, LOPT_MINPORT },
@@ -1930,6 +1932,7 @@ static int one_opt(int option, char *arg, char *errstr, char *gen_err, int comma
     case 'T':         /* --local-ttl */
     case LOPT_NEGTTL: /* --neg-ttl */
     case LOPT_MAXTTL: /* --max-ttl */
+    case LOPT_MAXCTTL: /* --max-cache-ttl */
       {
 	int ttl;
 	if (!atoi_check(arg, &ttl))
@@ -1938,6 +1941,8 @@ static int one_opt(int option, char *arg, char *errstr, char *gen_err, int comma
 	  daemon->neg_ttl = (unsigned long)ttl;
 	else if (option == LOPT_MAXTTL)
 	  daemon->max_ttl = (unsigned long)ttl;
+	else if (option == LOPT_MAXCTTL)
+	  daemon->max_cache_ttl = (unsigned long)ttl;
 	else
 	  daemon->local_ttl = (unsigned long)ttl;
 	break;