From bc68d5979ccf4beb2721e1e466539da550236f68 Mon Sep 17 00:00:00 2001
From: Nick Peng <pymumu@gmail.com>
Date: Sun, 22 May 2022 10:09:58 +0800
Subject: [PATCH] Support force not CNAME records

---
 src/dns_conf.c   |  3 ++-
 src/dns_conf.h   |  2 ++
 src/dns_server.c | 14 +++++++++++---
 3 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/src/dns_conf.c b/src/dns_conf.c
index bb548ed..c936f80 100644
--- a/src/dns_conf.c
+++ b/src/dns_conf.c
@@ -111,7 +111,7 @@ int dns_conf_rr_ttl_reply_max;
 int dns_conf_rr_ttl_min = 600;
 int dns_conf_rr_ttl_max;
 int dns_conf_force_AAAA_SOA;
-
+int dns_conf_force_no_cname;
 int dns_conf_ipset_timeout_enable;
 
 /* ECS */
@@ -1872,6 +1872,7 @@ static struct config_item _config_item[] = {
 	CONF_INT("rr-ttl-reply-max", &dns_conf_rr_ttl_reply_max, 0, CONF_INT_MAX),
 	CONF_INT("max-reply-ip-num", &dns_conf_max_reply_ip_num, 1, CONF_INT_MAX),
 	CONF_YESNO("force-AAAA-SOA", &dns_conf_force_AAAA_SOA),
+	CONF_YESNO("force-no-CNAME", &dns_conf_force_no_cname),
 	CONF_CUSTOM("force-qtype-SOA", _config_qtype_soa, NULL),
 	CONF_CUSTOM("blacklist-ip", _config_blacklist_ip, NULL),
 	CONF_CUSTOM("whitelist-ip", _conf_whitelist_ip, NULL),
diff --git a/src/dns_conf.h b/src/dns_conf.h
index 8224bc9..9ff8bc9 100644
--- a/src/dns_conf.h
+++ b/src/dns_conf.h
@@ -299,6 +299,8 @@ extern int dns_conf_rr_ttl_max;
 extern int dns_conf_force_AAAA_SOA;
 extern int dns_conf_ipset_timeout_enable;
 
+extern int dns_conf_force_no_cname;
+
 extern struct dns_edns_client_subnet dns_conf_ipv4_ecs;
 extern struct dns_edns_client_subnet dns_conf_ipv6_ecs;
 
diff --git a/src/dns_server.c b/src/dns_server.c
index 607d9d3..d3ec5a6 100644
--- a/src/dns_server.c
+++ b/src/dns_server.c
@@ -1372,13 +1372,17 @@ static int _dns_ip_address_check_add(struct dns_request *request, char *cname, u
 		tlog(TLOG_ERROR, "malloc failed");
 		return -1;
 	}
+	memset(addr_map, 0, sizeof(*addr_map));
 
 	addr_map->addr_type = addr_type;
 	addr_map->hitnum = 1;
 	addr_map->recv_tick = get_tick_count();
 	addr_map->ping_ttl = -1;
 	memcpy(addr_map->addr, addr, addr_len);
-	safe_strncpy(addr_map->cname, cname, DNS_MAX_CNAME_LEN);
+	if (dns_conf_force_no_cname == 0) {
+		safe_strncpy(addr_map->cname, cname, DNS_MAX_CNAME_LEN);
+	}
+
 	hash_add(request->ip_map, &addr_map->node, key);
 	pthread_mutex_unlock(&request->ip_map_lock);
 
@@ -1969,7 +1973,7 @@ static int _dns_server_process_answer_A(struct dns_rrs *rrs, struct dns_request
 		request->has_ipv4 = 1;
 		memcpy(request->ipv4_addr, addr, DNS_RR_A_LEN);
 		request->ttl_v4 = _dns_server_get_conf_ttl(ttl);
-		if (cname[0] != 0 && request->has_cname == 0) {
+		if (cname[0] != 0 && request->has_cname == 0 && dns_conf_force_no_cname == 0) {
 			request->has_cname = 1;
 			safe_strncpy(request->cname, cname, DNS_MAX_CNAME_LEN);
 		}
@@ -2045,7 +2049,7 @@ static int _dns_server_process_answer_AAAA(struct dns_rrs *rrs, struct dns_reque
 		request->has_ipv6 = 1;
 		memcpy(request->ipv6_addr, addr, DNS_RR_AAAA_LEN);
 		request->ttl_v6 = _dns_server_get_conf_ttl(ttl);
-		if (cname[0] != 0 && request->has_cname == 0) {
+		if (cname[0] != 0 && request->has_cname == 0 && dns_conf_force_no_cname == 0) {
 			request->has_cname = 1;
 			safe_strncpy(request->cname, cname, DNS_MAX_CNAME_LEN);
 		}
@@ -2317,6 +2321,10 @@ static int _dns_server_get_answer(struct dns_server_post_context *context)
 			} break;
 			case DNS_T_CNAME: {
 				char cname[DNS_MAX_CNAME_LEN];
+				if (dns_conf_force_no_cname) {
+					continue;
+				}
+
 				dns_get_CNAME(rrs, name, DNS_MAX_CNAME_LEN, &ttl, cname, DNS_MAX_CNAME_LEN);
 				tlog(TLOG_DEBUG, "name:%s ttl: %d cname: %s\n", name, ttl, cname);
 				safe_strncpy(request->cname, cname, DNS_MAX_CNAME_LEN);