diff --git a/dns.c b/dns.c
index 7a2921b..576f478 100644
--- a/dns.c
+++ b/dns.c
@@ -78,6 +78,10 @@ struct dns_rrs *dns_get_rrs_start(struct dns_packet *packet, int type, int *coun
 		break;
 	}
 
+	if (start == DNS_RR_END) {
+		return NULL;
+	}
+
 	return (struct dns_rrs *)(packet->data + start);
 }
 
@@ -111,7 +115,6 @@ int dns_rr_add_end(struct dns_packet *packet, int type, dns_type_t rrtype, int l
 	unsigned short *count;
 	unsigned short *start;
 
-	len += sizeof(*rrs);
 	if (packet->len + len > packet->size - sizeof(*packet)) {
 		return -1;
 	}
@@ -143,7 +146,7 @@ int dns_rr_add_end(struct dns_packet *packet, int type, dns_type_t rrtype, int l
 	rrs->len = len;
 	rrs->type = rrtype;
 	*start = packet->len;
-	packet->len += len;
+	packet->len += len + sizeof(*rrs);
 	return 0;
 }
 
@@ -254,6 +257,71 @@ int _dns_get_rr_head(struct dns_data_context *data_context, char *domain, int ma
 	return len;
 }
 
+int dns_add_CNAME(struct dns_packet *packet, char *domain, int ttl, char *cname)
+{
+	int maxlen = 0;
+	int len = 0;
+	struct dns_data_context data_context;
+	int rr_len = 0;
+
+	rr_len = strnlen(cname, maxlen - 1) + 1;
+	unsigned char *data = _dns_add_rrs_start(packet, &maxlen);
+	if (data == NULL) {
+		return -1;
+	}
+
+	if (rr_len >= maxlen) {
+		return -1;
+	}
+
+	data_context.data = data;
+	data_context.ptr = data;
+	data_context.maxsize = maxlen;
+
+	len = _dns_add_rr_head(&data_context, domain, DNS_T_CNAME, DNS_C_IN, ttl, rr_len);
+	if (len < 0) {
+		return -1;
+	}
+
+	memcpy(data_context.ptr, cname, rr_len);
+	data_context.ptr += rr_len;
+	len = data_context.ptr - data_context.data;
+
+	return dns_rr_add_end(packet, DNS_RRS_AN, DNS_T_CNAME, len);
+}
+
+int dns_get_CNAME(struct dns_rrs *rrs, char *domain, int maxsize, int *ttl, char *cname, int cname_size)
+{
+	int qtype = 0;
+	int qclass = 0;
+	int rr_len = 0;
+	int ret = 0;
+	struct dns_data_context data_context;
+
+	unsigned char *data = rrs->data;
+
+	if (rrs->type != DNS_T_CNAME) {
+		return -1;
+	}
+
+	data_context.data = data;
+	data_context.ptr = data;
+	data_context.maxsize = rrs->len;
+
+	ret = _dns_get_rr_head(&data_context, domain, maxsize, &qtype, &qclass, ttl, &rr_len);
+	if (ret < 0) {
+		return -1;
+	}
+
+	if (qtype != DNS_T_CNAME || rr_len > cname_size) {
+		return -1;
+	}
+
+	memcpy(cname, data_context.ptr, rr_len);
+
+	return 0;
+}
+
 int dns_add_A(struct dns_packet *packet, char *domain, int ttl, unsigned char addr[4])
 {
 	int maxlen = 0;
@@ -308,7 +376,7 @@ int dns_get_A(struct dns_rrs *rrs, char *domain, int maxsize, int *ttl, unsigned
 		return -1;
 	}
 
-	memcpy(addr, rrs->data, DNS_RR_A_LEN);
+	memcpy(addr, data_context.ptr, DNS_RR_A_LEN);
 
 	return 0;
 }
@@ -371,7 +439,7 @@ int dns_get_AAAA(struct dns_rrs *rrs, char *domain, int maxsize, int *ttl, unsig
 		return -1;
 	}
 
-	memcpy(addr, rrs->data, DNS_RR_AAAA_LEN);
+	memcpy(addr, data_context.ptr, DNS_RR_AAAA_LEN);
 
 	return 0;
 }
@@ -476,41 +544,108 @@ int _dns_encode_head(struct dns_context *context)
 	return len;
 }
 
+int dns_parse_domain(char *dns, int offset, char *domain, int *space)
+{
+	unsigned char val, *pval;
+	unsigned short len;
+
+	int sp = 0;
+	int domain_len = 0;
+	int org = 1;
+
+	while (1) {
+		pval = (unsigned char *)(dns + offset);
+		val = *pval;
+
+		if (val == 0) {
+			domain[domain_len - 1] = 0;
+			domain_len--;
+			if (org)
+				sp++;
+			break;
+		} else if (val <= 63) {
+			memcpy(domain + domain_len, dns + offset + 1, val);
+			domain_len += val;
+			domain[domain_len] = '.';
+			domain_len++;
+
+			offset += (val + 1);
+
+			if (org)
+				sp += (val + 1);
+		} else {
+			len = *(unsigned short *)(dns + offset);
+			len = ntohs(len);
+			len = len & (~0xc000);
+
+			if (org)
+				sp += 2;
+
+			org = 0;
+			offset = len;
+		}
+	}
+
+	*space = sp;
+
+	return 0;
+}
+
 int _dns_decode_domain(struct dns_context *context, char *output, int size)
 {
 	int output_len = 0;
 	int copy_len = 0;
 	int len = *(context->ptr);
+	unsigned char *ptr = context->ptr;
+	int is_compressed = 0;
 
-	while (*(context->ptr)) {
-		if (_dns_left_len(context) < 1) {
+	
+	int sp = 0;
+	dns_parse_domain(context->data, context->ptr - context->data, output, &sp);
+	context->ptr += sp;
+	return 0;
+	
+
+	while (1) {
+		len = *ptr;
+		if (len == 0) {
+			*output = 0;
+			ptr++;
+			break;
+		}
+
+		if (len >= 0xC0) {
+			ptr = context->data + (dns_read_short(&ptr) & 0x3FFF);
+			is_compressed = 1;
+			context->ptr += 2;
+			continue;
+		}
+
+		if (context->maxsize - (ptr - context->data) < 1) {
 			return -1;
 		}
 
-		context->ptr++;
+		ptr++;
 		if (output_len < size - 1) {
 			copy_len = (len < size - output_len) ? len : size - 1 - output_len;
-			if (_dns_left_len(context) < copy_len) {
+			if (context->maxsize - (ptr - context->data) < 1) {
 				return -1;
 			}
-			memcpy(output, context->ptr, copy_len);
+			memcpy(output, ptr, copy_len);
 		}
 
-		context->ptr += len;
+		ptr += len;
 		output += len;
 		output_len += len;
-
-		len = *(context->ptr);
-		if (len == 0) {
-			break;
-		}
 		*output = '.';
 		output++;
-
 	}
 
-	*output = 0;
-	context->ptr++;
+	if (is_compressed == 0) {
+		context->ptr = ptr;
+	}
+
+	printf("--%p\n", context->ptr);
 
 	return 0;
 }
@@ -536,13 +671,15 @@ int _dns_encode_domain(struct dns_context *context, char *domain)
 	}
 
 	*ptr_num = num;
-	*context->ptr = 0;
+	*(context->ptr) = 0;
+	context->ptr++;
 	return 0;
 }
 
 int _dns_decode_qr_head(struct dns_context *context, char *domain, int domain_size, int *qtype, int *qclass)
 {
 	int ret = 0;
+
 	ret = _dns_decode_domain(context, domain, domain_size);
 	if (ret < 0) {
 		return -1;
@@ -613,6 +750,53 @@ int _dns_encode_rr_head(struct dns_context *context, char *domain, int qtype, in
 	return 0;
 }
 
+int _dns_decode_CNAME(struct dns_context *context, char *cname, int cname_size)
+{
+	int ret = 0;
+	ret = _dns_decode_domain(context, cname, cname_size);
+	if (ret < 0) {
+		return -1;
+	}
+
+	return 0;
+}
+
+int _dns_encode_CNAME(struct dns_context *context, struct dns_rrs *rrs)
+{
+	int ret;
+	int qtype = 0;
+	int qclass = 0;
+	int ttl = 0;
+	char domain[DNS_MAX_CNAME_LEN];
+	int rr_len;
+	struct dns_data_context data_context;
+
+	data_context.data = rrs->data;
+	data_context.ptr = rrs->data;
+	data_context.maxsize = rrs->len;
+
+	ret = _dns_get_rr_head(&data_context, domain, DNS_MAX_CNAME_LEN, &qtype, &qclass, &ttl, &rr_len);
+	if (ret < 0) {
+		return -1;
+	}
+
+	if (rr_len > rrs->len) {
+		return -1;
+	}
+
+	ret = _dns_encode_rr_head(context, domain, qtype, qclass, ttl, rr_len);
+	if (ret < 0) {
+		return -1;
+	}
+
+	ret = _dns_encode_domain(context, (char *)rrs->data);
+	if (ret < 0) {
+		return -1;
+	}
+
+	return 0;
+}
+
 int _dns_decode_A(struct dns_context *context, unsigned char addr[4])
 {
 	if (_dns_left_len(context) < DNS_RR_A_LEN) {
@@ -748,6 +932,18 @@ int _dns_decode_an(struct dns_context *context)
 	}
 
 	switch (qtype) {
+	case DNS_T_CNAME: {
+		char cname[DNS_MAX_CNAME_LEN];
+		ret = _dns_decode_CNAME(context, cname, DNS_MAX_CNAME_LEN);
+		if (ret < 0) {
+			return -1;
+		}
+
+		ret = dns_add_CNAME(packet, domain, ttl, cname);
+		if (ret < 0) {
+			return -1;
+		}
+	} break;
 	case DNS_T_A: {
 		unsigned char addr[DNS_RR_A_LEN];
 		ret = _dns_decode_A(context, addr);
@@ -773,6 +969,7 @@ int _dns_decode_an(struct dns_context *context)
 		}
 	} break;
 	default:
+		context->ptr += rr_len;
 		break;
 	}
 
diff --git a/dns.h b/dns.h
index b1de1ea..64662e3 100644
--- a/dns.h
+++ b/dns.h
@@ -22,7 +22,7 @@
 #define DNS_RRS_NS 2
 #define DNS_RRS_NR 3
 
-#define DNS_RR_END (-1)
+#define DNS_RR_END (0XFFFF)
 
 typedef enum dns_class { DNS_C_IN = 1, DNS_C_ANY = 255 } dns_class_t;
 
@@ -118,6 +118,10 @@ struct dns_rrs *dns_get_rrs_next(struct dns_packet *packet, struct dns_rrs *rrs)
 
 struct dns_rrs *dns_get_rrs_start(struct dns_packet *packet, int type, int *count);
 
+int dns_add_CNAME(struct dns_packet *packet, char *domain, int ttl, char *cname);
+
+int dns_get_CNAME(struct dns_rrs *rrs, char *domain, int maxsize, int *ttl, char *cname, int cname_size);
+
 int dns_add_A(struct dns_packet *packet, char *domain, int ttl, unsigned char addr[4]);
 
 int dns_get_A(struct dns_rrs *rrs, char *domain, int maxsize, int *ttl, unsigned char addr[4]);
diff --git a/dns_server.c b/dns_server.c
index 8e4e6d4..245938f 100644
--- a/dns_server.c
+++ b/dns_server.c
@@ -46,7 +46,7 @@ static void tv_sub(struct timeval *out, struct timeval *in)
 
 void _dns_server_period_run()
 {
-	return;
+	
 	unsigned char packet_data[DNS_INPACKET_SIZE];
 	unsigned char data[DNS_INPACKET_SIZE];
 
@@ -64,7 +64,7 @@ void _dns_server_period_run()
 	socklen_t to_len = sizeof(to);
 
 	dns_packet_init(packet, DNS_INPACKET_SIZE, &head);
-	dns_add_domain(packet, "www.baidu.com", 1, 1);
+	dns_add_domain(packet, "www.huawei.com", 1, 1);
 	len = dns_encode(data, DNS_INPACKET_SIZE, packet);
 
 	memset(&to, 0, sizeof(to));
@@ -75,8 +75,6 @@ void _dns_server_period_run()
 	if (len < 0) {
 		printf("send failed.");
 	}
-
-	printf("send %d\n", len);
 }
 
 static int _dns_server_process(struct timeval *now)
@@ -97,6 +95,7 @@ static int _dns_server_process(struct timeval *now)
 	len = dns_decode(packet, DNS_INPACKET_SIZE, inpacket, len);
 	if (len) {
 		printf("decode failed.\n");
+		return 0;
 		goto errout;
 	}
 
@@ -116,6 +115,11 @@ static int _dns_server_process(struct timeval *now)
 			dns_get_A(rrs, name, 128, &ttl, addr);
 			printf("%s %d : %d.%d.%d.%d\n", name, ttl, addr[0], addr[1], addr[2], addr[3]);
 		} break;
+		case DNS_T_CNAME: {
+			char cname[128];
+			dns_get_CNAME(rrs, name, 128, &ttl, cname, 128);
+			printf("%s %d : %s\n", name, ttl, cname);
+		} break;
 		default:
 			break;
 		}
@@ -133,6 +137,7 @@ static int _dns_server_process(struct timeval *now)
 		}
 	}
 
+	printf("\n");
 	return 0;
 errout:
 	return -1;
@@ -157,7 +162,7 @@ int dns_server_run(void)
 			last = now;
 		}
 
-		num = epoll_wait(server.epoll_fd, events, DNS_MAX_EVENTS, 100);
+		num = epoll_wait(server.epoll_fd, events, DNS_MAX_EVENTS, 1000);
 		if (num < 0) {
 			gettimeofday(&now, 0);
 			usleep(100000);