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dns: support parser SRV record.

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This commit is contained in:
Nick Peng
2023-12-07 22:27:29 +08:00
parent 9f32e01971
commit 61a6e676bc
4 changed files with 170 additions and 1 deletions
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146
src/dns.c
View File

@@ -1104,6 +1104,60 @@ int dns_get_OPT_TCP_KEEPALIVE(struct dns_rrs *rrs, unsigned short *timeout)
return 0;
}
int dns_add_SRV(struct dns_packet *packet, dns_rr_type type, const char *domain, int ttl, int priority, int weight,
int port, const char *target)
{
unsigned char data[DNS_MAX_CNAME_LEN];
unsigned char *data_ptr = data;
int target_len = 0;
if (target == NULL) {
target = "";
}
target_len = strnlen(target, DNS_MAX_CNAME_LEN) + 1;
memcpy(data_ptr, &priority, sizeof(unsigned short));
data_ptr += sizeof(unsigned short);
memcpy(data_ptr, &weight, sizeof(unsigned short));
data_ptr += sizeof(unsigned short);
memcpy(data_ptr, &port, sizeof(unsigned short));
data_ptr += sizeof(unsigned short);
if (data_ptr - data + target_len >= DNS_MAX_CNAME_LEN) {
return -1;
}
safe_strncpy((char *)data_ptr, target, target_len);
data_ptr += target_len;
return _dns_add_RAW(packet, type, DNS_T_SRV, domain, ttl, data, data_ptr - data);
}
int dns_get_SRV(struct dns_rrs *rrs, char *domain, int maxsize, int *ttl, unsigned short *priority,
unsigned short *weight, unsigned short *port, char *target, int target_size)
{
unsigned char data[DNS_MAX_CNAME_LEN];
unsigned char *ptr = data;
int len = sizeof(data);
if (_dns_get_RAW(rrs, domain, maxsize, ttl, data, &len) != 0) {
return -1;
}
if (len < 6) {
return -1;
}
memcpy(priority, ptr, sizeof(unsigned short));
ptr += sizeof(unsigned short);
memcpy(weight, ptr, sizeof(unsigned short));
ptr += sizeof(unsigned short);
memcpy(port, ptr, sizeof(unsigned short));
ptr += sizeof(unsigned short);
safe_strncpy(target, (char *)ptr, target_size);
return 0;
}
int dns_add_HTTPS_start(struct dns_rr_nested *svcparam_buffer, struct dns_packet *packet, dns_rr_type type,
const char *domain, int ttl, int priority, const char *target)
{
@@ -1613,6 +1667,26 @@ static int _dns_encode_CNAME(struct dns_context *context, struct dns_rrs *rrs)
return 0;
}
static int _dns_decode_SRV(struct dns_context *context, unsigned short *priority, unsigned short *weight,
unsigned short *port, char *target, int target_size)
{
int ret = 0;
if (_dns_left_len(context) < 6) {
return -1;
}
*priority = _dns_read_short(&context->ptr);
*weight = _dns_read_short(&context->ptr);
*port = _dns_read_short(&context->ptr);
ret = _dns_decode_domain(context, target, target_size);
if (ret < 0) {
return -1;
}
return 0;
}
static int _dns_decode_SOA(struct dns_context *context, struct dns_soa *soa)
{
int ret = 0;
@@ -1702,6 +1776,54 @@ static int _dns_encode_SOA(struct dns_context *context, struct dns_rrs *rrs)
return 0;
}
static int _dns_encode_SRV(struct dns_context *context, struct dns_rrs *rrs)
{
int ret = 0;
int qtype = 0;
int qclass = 0;
int ttl = 0;
char domain[DNS_MAX_CNAME_LEN];
int rr_len = 0;
unsigned char *rr_len_ptr = NULL;
struct dns_context data_context;
_dns_init_context_by_rrs(rrs, &data_context);
ret = _dns_get_rr_head(&data_context, domain, DNS_MAX_CNAME_LEN, &qtype, &qclass, &ttl, &rr_len);
if (ret < 0) {
return -1;
}
ret = _dns_encode_rr_head(context, domain, qtype, qclass, ttl, rr_len, &rr_len_ptr);
if (ret < 0) {
return -1;
}
rr_len = 0;
if (_dns_left_len(context) < 6) {
return -1;
}
_dns_write_short(&context->ptr, *(unsigned short *)data_context.ptr);
data_context.ptr += 2;
_dns_write_short(&context->ptr, *(unsigned short *)data_context.ptr);
data_context.ptr += 2;
_dns_write_short(&context->ptr, *(unsigned short *)data_context.ptr);
data_context.ptr += 2;
rr_len += 6;
ret = _dns_encode_domain(context, (char *)data_context.ptr);
if (ret < 0) {
return -1;
}
rr_len += ret;
data_context.ptr += strnlen((char *)(data_context.ptr), DNS_MAX_CNAME_LEN) + 1;
_dns_write_short(&rr_len_ptr, rr_len);
return 0;
}
static int _dns_decode_opt_ecs(struct dns_context *context, struct dns_opt_ecs *ecs, int opt_len)
{
int len = 0;
@@ -2277,6 +2399,24 @@ static int _dns_decode_an(struct dns_context *context, dns_rr_type type)
return -1;
}
} break;
case DNS_T_SRV: {
unsigned short priority = 0;
unsigned short weight = 0;
unsigned short port = 0;
char target[DNS_MAX_CNAME_LEN];
ret = _dns_decode_SRV(context, &priority, &weight, &port, target, DNS_MAX_CNAME_LEN);
if (ret < 0) {
tlog(TLOG_DEBUG, "decode SRV failed, %s", domain);
return -1;
}
ret = dns_add_SRV(packet, type, domain, ttl, priority, weight, port, target);
if (ret < 0) {
tlog(TLOG_DEBUG, "add SRV failed, %s", domain);
return -1;
}
} break;
case DNS_T_OPT: {
unsigned char *opt_start = context->ptr;
ret = _dns_decode_opt(context, type, ttl, rr_len);
@@ -2393,6 +2533,12 @@ static int _dns_encode_an(struct dns_context *context, struct dns_rrs *rrs)
return -1;
}
break;
case DNS_T_SRV:
ret = _dns_encode_SRV(context, rrs);
if (ret < 0) {
return -1;
}
break;
case DNS_T_HTTPS:
ret = _dns_encode_HTTPS(context, rrs);
if (ret < 0) {

5
src/dns.h
View File

@@ -285,6 +285,11 @@ int dns_get_OPT_ECS(struct dns_rrs *rrs, struct dns_opt_ecs *ecs);
int dns_add_OPT_TCP_KEEPALIVE(struct dns_packet *packet, unsigned short timeout);
int dns_get_OPT_TCP_KEEPALIVE(struct dns_rrs *rrs, unsigned short *timeout);
int dns_add_SRV(struct dns_packet *packet, dns_rr_type type, const char *domain, int ttl, int priority, int weight,
int port, const char *target);
int dns_get_SRV(struct dns_rrs *rrs, char *domain, int maxsize, int *ttl, unsigned short *priority,
unsigned short *weight, unsigned short *port, char *target, int target_size);
/* the key must be added in orders, or dig will report FORMERR */
int dns_add_HTTPS_start(struct dns_rr_nested *svcparam_buffer, struct dns_packet *packet, dns_rr_type type,
const char *domain, int ttl, int priority, const char *target);

2
src/dns_client.c
View File

@@ -3494,7 +3494,7 @@ static int _dns_client_send_packet(struct dns_query_struct *query, void *packet,
}
}
total_server++;
tlog(TLOG_DEBUG, "send query to server %s", server_info->ip);
tlog(TLOG_DEBUG, "send query to server %s:%d", server_info->ip, server_info->port);
if (server_info->fd <= 0) {
ret = _dns_client_create_socket(server_info);
if (ret != 0) {

18
src/util.c
View File

@@ -1913,6 +1913,24 @@ static int _dns_debug_display(struct dns_packet *packet)
inet_ntop(AF_INET6, addr, req_host, sizeof(req_host));
printf("domain: %s AAAA: %s TTL:%d\n", name, req_host, ttl);
} break;
case DNS_T_SRV: {
unsigned short priority = 0;
unsigned short weight = 0;
unsigned short port = 0;
int ret = 0;
char name[DNS_MAX_CNAME_LEN] = {0};
char target[DNS_MAX_CNAME_LEN];
ret = dns_get_SRV(rrs, name, DNS_MAX_CNAME_LEN, &ttl, &priority, &weight, &port, target, DNS_MAX_CNAME_LEN);
if (ret < 0) {
tlog(TLOG_DEBUG, "decode SRV failed, %s", name);
return -1;
}
printf("domain: %s SRV: %s TTL: %d priority: %d weight: %d port: %d\n", name, target, ttl, priority,
weight, port);
} break;
case DNS_T_HTTPS: {
char name[DNS_MAX_CNAME_LEN] = {0};
char target[DNS_MAX_CNAME_LEN] = {0};