serve-expired: support config reply ttl

ReadMe.md

@@ -537,6 +537,7 @@ https://github.com/pymumu/smartdns/releases
 |prefetch-domain|域名预先获取功能|no|[yes\|no]|prefetch-domain yes
 |serve-expired|过期缓存服务功能|no|[yes\|no]，开启此功能后，如果有请求时尝试回应TTL为0的过期记录，并并发查询记录，以避免查询等待|serve-expired yes
 |serve-expired-ttl|过期缓存服务最长超时时间|0|秒，0：表示停用超时，> 0表示指定的超时的秒数|serve-expired-ttl 0
+|serve-expired-reply-ttl|回应的过期缓存TTL|5|秒，0：表示停用超时，> 0表示指定的超时的秒数|serve-expired-reply-ttl 30
 |dualstack-ip-selection|双栈IP优选|no|[yes\|no]|dualstack-ip-selection yes
 |dualstack-ip-selection-threshold|双栈IP优选阈值|30ms|毫秒|dualstack-ip-selection-threshold [0-1000]
 |ca-file|证书文件|/etc/ssl/certs/ca-certificates.crt|路径|ca-file /etc/ssl/certs/ca-certificates.crt

ReadMe_en.md

@@ -531,6 +531,7 @@ Note: Merlin firmware is derived from ASUS firmware and can theoretically be use
 |prefetch-domain|domain prefetch feature|no|[yes\|no]|prefetch-domain yes
 |serve-expired|Cache serve expired feature|no|[yes\|no], Attempts to serve old responses from cache with a TTL of 0 in the response without waiting for the actual resolution to finish.|serve-expired yes
 |serve-expired-ttl|Cache serve expired limite TTL|0|second，0：disable，> 0  seconds after expiration|serve-expired-ttl 0
+|serve-expired-reply-ttl|TTL value to use when replying with expired data|5|second，0：disable，> 0  seconds after expiration|serve-expired-reply-ttl 30
 |dualstack-ip-selection|Dualstack ip selection|no|[yes\|no]|dualstack-ip-selection yes
 |dualstack-ip-selection-threshold|Dualstack ip select threadhold|30ms|millisecond|dualstack-ip-selection-threshold [0-1000]
 |ca-file|certificate file|/etc/ssl/certs/ca-certificates.crt|path|ca-file /etc/ssl/certs/ca-certificates.crt

etc/smartdns/smartdns.conf

@@ -58,6 +58,10 @@ cache-size 4096
 # serve-expired-ttl [num]
 # serve-expired-ttl 0
 
+# reply TTL value to use when replying with expired data
+# serve-expired-reply-ttl [num]
+# serve-expired-reply-ttl 30
+
 # List of hosts that supply bogus NX domain results 
 # bogus-nxdomain [ip/subnet]
 

src/dns_conf.c

@@ -50,6 +50,7 @@ int dns_conf_cachesize = DEFAULT_DNS_CACHE_SIZE;
 int dns_conf_prefetch = 0;
 int dns_conf_serve_expired = 0;
 int dns_conf_serve_expired_ttl = 0;
+int dns_conf_serve_expired_reply_ttl = 5;
 
 /* upstream servers */
 struct dns_servers dns_conf_servers[DNS_MAX_SERVERS];
@@ -1366,6 +1367,7 @@ static struct config_item _config_item[] = {
 	CONF_YESNO("prefetch-domain", &dns_conf_prefetch),
 	CONF_YESNO("serve-expired", &dns_conf_serve_expired),
 	CONF_INT("serve-expired-ttl", &dns_conf_serve_expired_ttl, 0, CONF_INT_MAX),
+	CONF_INT("serve-expired-reply-ttl", &dns_conf_serve_expired_reply_ttl, 0, CONF_INT_MAX),
 	CONF_YESNO("dualstack-ip-selection", &dns_conf_dualstack_ip_selection),
 	CONF_INT("dualstack-ip-selection-threshold", &dns_conf_dualstack_ip_selection_threshold, 0, 1000),
 	CONF_CUSTOM("log-level", _config_log_level, NULL),

src/dns_conf.h

@@ -205,6 +205,7 @@ extern int dns_conf_cachesize;
 extern int dns_conf_prefetch;
 extern int dns_conf_serve_expired;
 extern int dns_conf_serve_expired_ttl;
+extern int dns_conf_serve_expired_reply_ttl;
 extern struct dns_servers dns_conf_servers[DNS_MAX_SERVERS];
 extern int dns_conf_server_num;
 

src/dns_server.c

@@ -2264,6 +2264,16 @@ static void _dns_server_process_speed_check_rule(struct dns_request *request)
 	request->check_order_list = check_order;
 }
 
+static int _dns_server_get_expired_ttl_reply(struct dns_cache *dns_cache)
+{
+	int ttl = dns_cache_get_ttl(dns_cache);
+	if (ttl > 0) {
+		return ttl;
+	}
+
+	return dns_conf_serve_expired_reply_ttl;
+}
+
 static int _dns_server_process_cache_addr(struct dns_request *request, struct dns_cache *dns_cache)
 {
 	struct dns_cache_addr *cache_addr = (struct dns_cache_addr *)dns_cache_get_data(dns_cache);
@@ -2275,12 +2285,12 @@ static int _dns_server_process_cache_addr(struct dns_request *request, struct dn
 	switch (request->qtype) {
 	case DNS_T_A:
 		memcpy(request->ipv4_addr, cache_addr->addr_data.ipv4_addr, DNS_RR_A_LEN);
-		request->ttl_v4 = dns_cache_get_ttl(dns_cache);
+		request->ttl_v4 = _dns_server_get_expired_ttl_reply(dns_cache);
 		request->has_ipv4 = 1;
 		break;
 	case DNS_T_AAAA:
 		memcpy(request->ipv6_addr, cache_addr->addr_data.ipv6_addr, DNS_RR_AAAA_LEN);
-		request->ttl_v6 = dns_cache_get_ttl(dns_cache);
+		request->ttl_v6 = _dns_server_get_expired_ttl_reply(dns_cache);
 		request->has_ipv6 = 1;
 		break;
 	default: