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update

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This commit is contained in:
Nick Peng
2018-05-14 00:44:54 +08:00
parent 83d0d5cf6f
commit 07a114666f
3 changed files with 231 additions and 25 deletions
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235
dns.c
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@@ -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;
}