@@ -60,6 +60,7 @@

 #  2007-05-26  changed darwin module link flags (instead of -bundle_loader ser

 #               -flat_namespace -undefined suppress) (andrei)

 #  2007-07-07  added HAVE_SCHED_SETSCHEDULER for linux (andrei)

+#  2007-07-18  added DNS_WATCHDOG_SUPPORT (Miklos)

 # check if already included/exported

@@ -403,6 +404,11 @@ endif

 #         unsafe)

 # -DUSE_NAPTR

 #		 turns on naptr support (but must be also enabled from the config)

+# -DDNS_WATCHDOG_SUPPORT

+#		turns on DNS watchdog support which can be used to inform the

+#		core that the DNS servers are down. No DNS query is performed

+#		when the servers are unreachable, and even expired resource

+#		records are used from the cache. (requires external watchdog)

 # Sometimes is needes correct non-quoted $OS. HACK: gcc translates known OS to number ('linux'), so there is added underscore

@@ -423,6 +429,7 @@ DEFS+= $(extra_defs) \

 	 -DUSE_DNS_FAILOVER \

 	 -DUSE_DST_BLACKLIST \

 	 -DUSE_NAPTR \

+	 #-DDNS_WATCHDOG_SUPPORT \

 	 #-DLL_MALLOC \

 	 #-DSF_MALLOC \

 	 #-DDL_MALLOC \

@@ -57,7 +57,17 @@ static const char* dns_cache_debug_all_doc[] = {

 	"complete dns debug  dump",    /* Documentation string */

 	0                              /* Method signature(s) */

 };

-#endif

+

+#ifdef DNS_WATCHDOG_SUPPORT

+void dns_set_server_state_rpc(rpc_t* rpc, void* ctx);

+

+static const char* dns_set_server_state_doc[] = {

+	"sets the state of the DNS servers " \

+	"(0: all the servers are down, 1: at least one server is up)",    /* Documentation string */

+	0                              /* Method signature(s) */

+};

+#endif /* DNS_WATCHDOG_SUPPORT */

+#endif /* USE_DNS_CACHE */

 #ifdef USE_DST_BLACKLIST

 void dst_blst_debug(rpc_t* rpc, void* ctx);

 void dst_blst_mem_info(rpc_t* rpc, void* ctx);

@@ -469,6 +479,9 @@ rpc_export_t core_rpc_methods[] = {

 	{"dns.mem_info",          dns_cache_mem_info,     dns_cache_mem_info_doc,     0	},

 	{"dns.debug",          dns_cache_debug,           dns_cache_debug_doc,        0	},

 	{"dns.debug_all",      dns_cache_debug_all,       dns_cache_debug_all_doc,        0	},

+#ifdef DNS_WATCHDOG_SUPPORT

+	{"dns.set_server_state",   dns_set_server_state_rpc, dns_set_server_state_doc, 0 },

+#endif

 #endif

 #ifdef USE_DST_BLACKLIST

 	{"dst_blacklist.mem_info",  dst_blst_mem_info,     dst_blst_mem_info_doc,     0	},

@@ -33,6 +33,8 @@

  *  2007-06-14  dns iterate through A & AAAA records fix (andrei)

  *  2007-06-15  srv rr weight based load balancing support (andrei)

  *  2007-06-16  naptr support (andrei)

+ *  2008-07-18  DNS watchdog support -- can be used to inform the core

+ *              that the DNS servers are down (Miklos)

  */

 #ifdef USE_DNS_CACHE

@@ -112,6 +114,10 @@ static struct dns_hash_head* dns_hash=0;

 static struct timer_ln* dns_timer_h=0;

+#ifdef DNS_WATCHDOG_SUPPORT

+static atomic_t *dns_servers_up = NULL;

+#endif

+

 static const char* dns_str_errors[]={

@@ -192,6 +198,11 @@ inline static int dns_cache_free_mem(unsigned int target, int expired_only);

 static ticks_t dns_timer(ticks_t ticks, struct timer_ln* tl, void* data)

 {

+#ifdef DNS_WATCHDOG_SUPPORT

+	/* do not clean the hash table if the servers are down */

+	if (atomic_get(dns_servers_up) == 0)

+		return (ticks_t)(-1);

+#endif

 	if (*dns_cache_mem_used>12*(dns_cache_max_mem/16)){ /* ~ 75% used */

 		dns_cache_free_mem(dns_cache_max_mem/2, 1); 

 	}else{

@@ -210,6 +221,12 @@ void destroy_dns_cache()

 		timer_free(dns_timer_h);

 		dns_timer_h=0;

 	}

+#ifdef DNS_WATCHDOG_SUPPORT

+	if (dns_servers_up){

+		shm_free(dns_servers_up);

+		dns_servers_up=0;

+	}

+#endif

 	if (dns_hash_lock){

 		lock_destroy(dns_hash_lock);

 		lock_dealloc(dns_hash_lock);

@@ -277,6 +294,15 @@ int init_dns_cache()

 		ret=-1;

 		goto error;

 	}

+

+#ifdef DNS_WATCHDOG_SUPPORT

+	dns_servers_up=shm_malloc(sizeof(atomic_t));

+	if (dns_servers_up==0){

+		ret=E_OUT_OF_MEM;

+		goto error;

+	}

+	atomic_set(dns_servers_up, 1);

+#endif

 	/* fix options */

 	dns_cache_max_mem<<=10; /* Kb */ /* TODO: test with 0 */

@@ -413,6 +439,11 @@ inline static struct dns_hash_entry* _dns_hash_find(str* name, int type,

 	ticks_t now;

 	int cname_chain;

 	str cname;

+#ifdef DNS_WATCHDOG_SUPPORT

+	int servers_up;

+

+	servers_up = atomic_get(dns_servers_up);

+#endif

 	cname_chain=0;

 	ret=0;

@@ -425,8 +456,14 @@ again:

 												name->len, type, *h);

 #endif

 	clist_foreach_safe(&dns_hash[*h], e, tmp, next){

-		/* automatically remove expired elements */

-		if ((s_ticks_t)(now-e->expire)>=0){

+		if (

+#ifdef DNS_WATCHDOG_SUPPORT

+			/* remove expired elements only when the dns servers are up */

+			servers_up &&

+#endif

+			/* automatically remove expired elements */

+			((s_ticks_t)(now-e->expire)>=0)

+		) {

 				_dns_hash_remove(e);

 		}else if ((e->type==type) && (e->name_len==name->len) &&

 			(strncasecmp(e->name, name->s, e->name_len)==0)){

@@ -1476,6 +1513,10 @@ inline static struct dns_hash_entry* dns_cache_do_request(str* name, int type)

 				goto end;/* we do not cache obvious stuff */

 		}

 	}

+#ifdef DNS_WATCHDOG_SUPPORT

+	if (atomic_get(dns_servers_up)==0)

+		goto end; /* the servers are down, needless to perform the query */

+#endif

 	if (name->len>=MAX_DNS_NAME){

 		LOG(L_ERR, "ERROR: dns_cache_do_request: name too long (%d chars)\n",

 					name->len);

@@ -1660,11 +1701,22 @@ inline static struct dns_rr* dns_entry_get_rr(	struct dns_hash_entry* e,

 	struct dns_rr* rr;

 	int n;

 	int flags;

+#ifdef DNS_WATCHDOG_SUPPORT

+	int servers_up;

+

+	servers_up = atomic_get(dns_servers_up);

+#endif

 	flags=0;

 	for(rr=e->rr_lst, n=0;rr && (n<*no);rr=rr->next, n++);/* skip *no records*/

 	for(;rr;rr=rr->next){

-		if ((s_ticks_t)(now-e->expire)>=0) /* expired entry */

+		if (

+#ifdef DNS_WATCHDOG_SUPPORT

+			/* check the expiration time only when the servers are up */

+			servers_up &&

+#endif

+			((s_ticks_t)(now-rr->expire)>=0) /* expired rr */

+		)

 			continue;

 		if (rr->err_flags){ /* bad rr */

 			continue;

@@ -1741,6 +1793,11 @@ inline static struct dns_rr* dns_srv_get_nxt_rr(struct dns_hash_entry* e,

 			unsigned r_sum;

 			struct dns_rr* rr;

 			}r_sums[MAX_SRV_GRP_IDX];

+#ifdef DNS_WATCHDOG_SUPPORT

+	int servers_up;

+

+	servers_up = atomic_get(dns_servers_up);

+#endif

 	rand_w=0;

 	for(rr=e->rr_lst, n=0;rr && (n<*no);rr=rr->next, n++);/* skip *no records*/

@@ -1755,7 +1812,12 @@ retry:

 	found=0;

 	for (idx=0;rr && (prio==((struct srv_rdata*)rr->rdata)->priority) &&

 						(idx < MAX_SRV_GRP_IDX); idx++, rr=rr->next){

-		if ( ((s_ticks_t)(now-rr->expire)>=0) /* expired entry */ ||

+		if ((

+#ifdef DNS_WATCHDOG_SUPPORT

+			/* check the expiration time only when the servers are up */

+			servers_up &&

+#endif

+			((s_ticks_t)(now-rr->expire)>=0) /* expired entry */) ||

 				(rr->err_flags) /* bad rr */ ||

 				(srv_marked(tried, idx)) ) /* already tried */{

 			r_sums[idx].r_sum=0; /* 0 sum, to skip over it */

@@ -2939,6 +3001,16 @@ int dns_srv_get_ip(str* name, struct ip_addr* ip, unsigned short* port,

 }

+#ifdef DNS_WATCHDOG_SUPPORT

+/* sets the state of the DNS servers:

+ * 1: at least one server is up

+ * 0: all the servers are down

+ */

+void dns_set_server_state(int state)

+{

+	atomic_set(dns_servers_up, state);

+}

+#endif /* DNS_WATCHDOG_SUPPORT */

 /* rpc functions */

 void dns_cache_mem_info(rpc_t* rpc, void* ctx)

@@ -3026,5 +3098,16 @@ void dns_cache_debug_all(rpc_t* rpc, void* ctx)

 	UNLOCK_DNS_HASH();

 }

+#ifdef DNS_WATCHDOG_SUPPORT

+/* sets the DNS server states */

+void dns_set_server_state_rpc(rpc_t* rpc, void* ctx)

+{

+	int	state;

+

+	if (rpc->scan(ctx, "d", &state) < 1)

+		return;

+	dns_set_server_state(state);

+}

+#endif /* DNS_WATCHDOG_SUPPORT */

 #endif

@@ -48,6 +48,10 @@

 #error "DNS FAILOVER requires DNS CACHE support (define USE_DNS_CACHE)"

 #endif

+#if defined(DNS_WATCHDOG_SUPPORT) && !defined(USE_DNS_CACHE)

+#error "DNS WATCHDOG requires DNS CACHE support (define USE_DNS_CACHE)"

+#endif

+

 /* uncomment the define below for SRV weight based load balancing */

 #define DNS_SRV_LB

@@ -308,4 +312,13 @@ inline static int dns_sip_resolve2su(struct dns_srv_handle* h,

 		init_su(su, &ip, port);

 	return ret;

 }

+

+#ifdef DNS_WATCHDOG_SUPPORT

+/* sets the state of the DNS servers:

+ * 1: at least one server is up

+ * 0: all the servers are down

+ */

+void dns_set_server_state(int state);

+#endif /* DNS_WATCHDOG_SUPPORT */

+

 #endif

@@ -260,6 +260,12 @@

 #define USE_DNS_FAILOVER_STR ""

 #endif

+#ifdef DNS_WATCHDOG_SUPPORT

+#define DNS_WATCHDOG_SUPPORT_STR ", DNS_WATCHDOG_SUPPORT"

+#else

+#define DNS_WATCHDOG_SUPPORT_STR ""

+#endif

+

 #ifdef USE_NAPTR

 #define USE_NAPTR_STR ", USE_NAPTR"

 #else

@@ -297,7 +303,7 @@

 	USE_FUTEX_STR \

 	FAST_LOCK_STR NOSMP_STR USE_PTHREAD_MUTEX_STR USE_POSIX_SEM_STR \

 	USE_SYSV_SEM_STR USE_COMP_STR USE_DNS_CACHE_STR USE_DNS_FAILOVER_STR \

-	USE_NAPTR_STR USE_DST_BLACKLIST_STR

+	DNS_WATCHDOG_SUPPORT_STR USE_NAPTR_STR USE_DST_BLACKLIST_STR

 #endif