daxi20/smartdns
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code enhancement

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This commit is contained in:
Nick Peng
2019-02-02 19:28:31 +08:00
parent 05a24264aa
commit 7add2b82ae
2 changed files with 31 additions and 9 deletions
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24
src/dns.c
View File

@@ -144,8 +144,8 @@ unsigned char *_dns_add_rrs_start(struct dns_packet *packet, int *maxlen)
unsigned char *end = packet->data + packet->len; unsigned char *end = packet->data + packet->len;
rrs = (struct dns_rrs *)end; rrs = (struct dns_rrs *)end;
*maxlen = packet->size - packet->len - sizeof(*packet); *maxlen = packet->size - packet->len - sizeof(*packet) - sizeof(*rrs);
if (packet->len >= packet->size - sizeof(*packet)) { if (*maxlen <= 0) {
/* if size exceeds max packet size, return NULL */ /* if size exceeds max packet size, return NULL */
return NULL; return NULL;
} }
@@ -163,7 +163,7 @@ int dns_rr_add_end(struct dns_packet *packet, int type, dns_type_t rtype, int le
unsigned short *start; unsigned short *start;
rrs = (struct dns_rrs *)end; rrs = (struct dns_rrs *)end;
if (packet->len + len > packet->size - sizeof(*packet)) { if (packet->len + len > packet->size - sizeof(*packet) - sizeof(*rrs)) {
return -1; return -1;
} }
@@ -227,7 +227,7 @@ int _dns_add_qr_head(struct dns_data_context *data_context, char *domain, int qt
* |qtype | qclass | * |qtype | qclass |
*/ */
while (1) { while (1) {
if (_dns_data_left_len(data_context) < 1) { if (_dns_data_left_len(data_context) < 4) {
return -1; return -1;
} }
*data_context->ptr = *domain; *data_context->ptr = *domain;
@@ -259,8 +259,8 @@ int _dns_get_qr_head(struct dns_data_context *data_context, char *domain, int ma
/* |domain | /* |domain |
* |qtype | qclass | * |qtype | qclass |
*/ */
for (i = 0; i < maxsize; i++) { for (i = 0; i < maxsize - 1; i++) {
if (_dns_data_left_len(data_context) < 1) { if (_dns_data_left_len(data_context) < 4) {
return -1; return -1;
} }
*domain = *data_context->ptr; *domain = *data_context->ptr;
@@ -275,6 +275,8 @@ int _dns_get_qr_head(struct dns_data_context *data_context, char *domain, int ma
data_context->ptr++; data_context->ptr++;
} }
*domain = '\0';
if (_dns_data_left_len(data_context) < 4) { if (_dns_data_left_len(data_context) < 4) {
return -1; return -1;
} }
@@ -1775,6 +1777,10 @@ static int _dns_encode_body(struct dns_context *context)
int dns_packet_init(struct dns_packet *packet, int size, struct dns_head *head) int dns_packet_init(struct dns_packet *packet, int size, struct dns_head *head)
{ {
struct dns_head *init_head = &packet->head; struct dns_head *init_head = &packet->head;
if (size < sizeof(*packet)) {
return -1;
}
memset(packet, 0, size); memset(packet, 0, size);
packet->size = size; packet->size = size;
init_head->id = head->id; init_head->id = head->id;
@@ -1810,7 +1816,11 @@ int dns_decode(struct dns_packet *packet, int maxsize, unsigned char *data, int
context.ptr = data; context.ptr = data;
context.maxsize = size; context.maxsize = size;
dns_packet_init(packet, maxsize, head); ret = dns_packet_init(packet, maxsize, head);
if (ret != 0) {
return -1;
}
ret = _dns_decode_head(&context); ret = _dns_decode_head(&context);
if (ret < 0) { if (ret < 0) {
return -1; return -1;

16
src/dns_client.c
View File

@@ -1650,10 +1650,16 @@ static int _dns_client_send_query(struct dns_query_struct *query, char *doamin)
head.ra = 0; head.ra = 0;
head.rcode = 0; head.rcode = 0;
dns_packet_init(packet, DNS_PACKSIZE, &head); if(dns_packet_init(packet, DNS_PACKSIZE, &head) != 0) {
tlog(TLOG_ERROR, "init packet failed.");
return -1;
}
/* add question */ /* add question */
dns_add_domain(packet, doamin, query->qtype, DNS_C_IN); if (dns_add_domain(packet, doamin, query->qtype, DNS_C_IN) != 0) {
tlog(TLOG_ERROR, "add domain to packet failed.");
return -1;
}
dns_set_OPT_payload_size(packet, DNS_IN_PACKSIZE); dns_set_OPT_payload_size(packet, DNS_IN_PACKSIZE);
@@ -1669,6 +1675,12 @@ static int _dns_client_send_query(struct dns_query_struct *query, char *doamin)
return -1; return -1;
} }
if (encode_len > DNS_IN_PACKSIZE) {
tlog(TLOG_ERROR, "size is invalid.");
abort();
return -1;
}
/* send query packet */ /* send query packet */
return _dns_client_send_packet(query, inpacket, encode_len); return _dns_client_send_packet(query, inpacket, encode_len);
} }