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Update code

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This commit is contained in:
Nick Peng
2018-05-12 00:24:18 +08:00
parent bbb8742283
commit b8cb84fc4a
3 changed files with 364 additions and 149 deletions
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482
dns.c
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@@ -6,217 +6,425 @@
short dns_read_short(unsigned char **buffer)
{
unsigned short value;
unsigned short value;
value = *((unsigned short *)(*buffer));
*buffer += 2;
value = *((unsigned short *)(*buffer));
*buffer += 2;
return ntohs(value);
return ntohs(value);
}
void dns_write_char(unsigned char **buffer, unsigned char value)
{
**buffer = value;
*buffer += 1;
**buffer = value;
*buffer += 1;
}
unsigned char dns_read_char(unsigned char **buffer)
{
unsigned char value = **buffer;
*buffer += 1;
return value;
unsigned char value = **buffer;
*buffer += 1;
return value;
}
void dns_write_short(unsigned char **buffer, unsigned short value)
{
value = htons(value);
*((unsigned short *)(*buffer)) = value;
*buffer += 2;
value = htons(value);
*((unsigned short *)(*buffer)) = value;
*buffer += 2;
}
void dns_write_int(unsigned char **buffer, unsigned int value)
{
value = htons(value);
*((unsigned int *)(*buffer)) = value;
*buffer += 4;
value = htons(value);
*((unsigned int *)(*buffer)) = value;
*buffer += 4;
}
unsigned int dns_read_int(unsigned char **buffer)
{
unsigned int value;
unsigned int value;
value = *((unsigned int *)(*buffer));
*buffer += 4;
value = *((unsigned int *)(*buffer));
*buffer += 4;
return ntohs(value);
return ntohs(value);
}
struct dns_rrs *dns_rr_get_start(struct dns_packet *packet, int type, int *count)
{
unsigned short start;
struct dns_head *head = &packet->head;
switch (type) {
case DNS_RR_QD:
*count = head->qdcount;
start = packet->questions;
break;
case DNS_RR_AN:
*count = head->ancount;
start = packet->answers;
break;
case DNS_RR_NS:
*count = head->nscount;
start = packet->nameservers;
break;
case DNS_RR_NR:
*count = head->nrcount;
start = packet->additional;
break;
default:
return NULL;
break;
}
return (struct dns_rrs *)(packet->data + start);
}
struct dns_rrs *dns_rr_get_next(struct dns_packet *packet, struct dns_rrs *rrs)
{
if (rrs->next == 0) {
return NULL;
}
return (struct dns_rrs *)(packet->data + rrs->next);
}
unsigned char *dns_rr_add_start(struct dns_packet *packet, int *maxlen)
{
struct dns_rrs *rrs;
unsigned char *end = packet->data + packet->len;
rrs = (struct dns_rrs *)end;
*maxlen = packet->size - packet->len - sizeof(*packet);
if (packet->len >= packet->size - sizeof(*packet)) {
return NULL;
}
return rrs->data;
}
int dns_rr_add_end(struct dns_packet *packet, int type, int len)
{
struct dns_rrs *rrs;
struct dns_head *head = &packet->head;
unsigned char *end = packet->data + packet->len;
rrs = (struct dns_rrs *)end;
unsigned short *count;
unsigned short *start;
if (packet->len + len > packet->size - sizeof(*packet)) {
return -1;
}
switch (type) {
case DNS_RR_QD:
count = &head->qdcount;
start = &packet->questions;
break;
case DNS_RR_AN:
count = &head->ancount;
start = &packet->answers;
break;
case DNS_RR_NS:
count = &head->nscount;
start = &packet->nameservers;
break;
case DNS_RR_NR:
count = &head->nrcount;
start = &packet->additional;
break;
default:
return -1;
break;
}
*count += 1;
rrs->next = *start;
rrs->len = len;
*start = packet->len;
packet->len += len;
return 0;
}
int dns_decode_head(struct dns_head *head, unsigned char **data)
{
unsigned int fields;
unsigned char *start = *data;
unsigned char *end = start;
unsigned int fields;
unsigned char *start = *data;
unsigned char *end = start;
head->id = dns_read_short(data);
fields = dns_read_short(data);
head->qr = (fields & QR_MASK) >> 15;
head->opcode = (fields & OPCODE_MASK) >> 11;
head->aa = (fields & AA_MASK) >> 10;
head->tc = (fields & TC_MASK) >> 9;
head->rd = (fields & RD_MASK) >> 8;
head->ra = (fields & RA_MASK) >> 7;
head->rcode = (fields & RCODE_MASK) >> 0;
head->qdcount = dns_read_short(data);
head->ancount = dns_read_short(data);
head->nscount = dns_read_short(data);
head->nrcount = dns_read_short(data);
head->id = dns_read_short(data);
fields = dns_read_short(data);
head->qr = (fields & QR_MASK) >> 15;
head->opcode = (fields & OPCODE_MASK) >> 11;
head->aa = (fields & AA_MASK) >> 10;
head->tc = (fields & TC_MASK) >> 9;
head->rd = (fields & RD_MASK) >> 8;
head->ra = (fields & RA_MASK) >> 7;
head->rcode = (fields & RCODE_MASK) >> 0;
head->qdcount = dns_read_short(data);
head->ancount = dns_read_short(data);
head->nscount = dns_read_short(data);
head->nrcount = dns_read_short(data);
end = *data;
return start - end;
end = *data;
return start - end;
}
int dns_encode_head(unsigned char **data, struct dns_head *head)
{
dns_write_short(data, head->id);
dns_write_short(data, head->id);
int fields = 0;
fields |= (head->qr << 15) & QR_MASK;
fields |= (head->rcode << 0) & RCODE_MASK;
dns_write_short(data, fields);
int fields = 0;
fields |= (head->qr << 15) & QR_MASK;
fields |= (head->rcode << 0) & RCODE_MASK;
dns_write_short(data, fields);
dns_write_short(data, head->qdcount);
dns_write_short(data, head->ancount);
dns_write_short(data, head->nscount);
dns_write_short(data, head->nrcount);
return 0;
dns_write_short(data, head->qdcount);
dns_write_short(data, head->ancount);
dns_write_short(data, head->nscount);
dns_write_short(data, head->nrcount);
return 0;
}
int dns_get_domain(char *output, int size, unsigned char *data)
int dns_decode_domain(char *output, int size, unsigned char *data)
{
int i = 0;
int output_len = 0;
int copy_len = 0;
int total_len = 0;
int i = 0;
int output_len = 0;
int copy_len = 0;
int total_len = 0;
while (data[i]) {
int len = data[i];
while (data[i]) {
int len = data[i];
if (i != 0) {
*output = '.';
output++;
}
if (i != 0) {
*output = '.';
output++;
}
i++;
total_len++;
if (output_len < size - 1) {
copy_len = (len < size - output_len) ? len : size - 1 - output_len;
memcpy(output, data + i, copy_len);
}
i += len;
output += len;
output_len += len;
total_len += len;
}
i++;
total_len++;
if (output_len < size - 1) {
copy_len = (len < size - output_len) ? len : size - 1 - output_len;
memcpy(output, data + i, copy_len);
}
i += len;
output += len;
output_len += len;
total_len += len;
}
*output = 0;
total_len++;
return total_len;
*output = 0;
total_len++;
return total_len;
}
int dns_encode_domain(unsigned char *output, int size, char *domain)
{
int i = 0;
int num = 0;
int total_len = 0;
unsigned char *ptr_num = output++;
total_len++;
while (i < size && *domain != 0) {
if (*domain == '.') {
*ptr_num = num;
num = 0;
ptr_num = output;
domain++;
output++;
total_len++;
continue;
}
*output = *domain;
num++;
output++;
domain++;
total_len++;
}
*ptr_num = num;
*output = 0;
total_len++;
return total_len;
int i = 0;
int num = 0;
int total_len = 0;
unsigned char *ptr_num = output++;
total_len++;
while (i < size && *domain != 0) {
if (*domain == '.') {
*ptr_num = num;
num = 0;
ptr_num = output;
domain++;
output++;
total_len++;
continue;
}
*output = *domain;
num++;
output++;
domain++;
total_len++;
}
*ptr_num = num;
*output = 0;
total_len++;
return total_len;
}
int dns_decode_qd(unsigned char *data, int size, char *domain, int domain_size, int *qtype, int *qclass)
{
int len = 0;
len = dns_get_domain(domain, domain_size, data);
data += len;
*qtype = dns_read_short(&data);
*qclass = dns_read_short(&data);
int len = 0;
len = dns_decode_domain(domain, domain_size, data);
data += len;
*qtype = dns_read_short(&data);
*qclass = dns_read_short(&data);
return len;
return len;
}
int dns_add_domain(struct dns_packet *packet, char *domain, int qtype, int qclass)
{
int maxlen = 0;
int i;
int len = 0;
unsigned char *data = dns_rr_add_start(packet, &maxlen);
unsigned char *data_ptr = data;
if (data == NULL) {
return -1;
}
for (i = 0; i < maxlen - 4; i++) {
*data = *domain;
if (*domain == '\0') {
data++;
i++;
break;
}
data++;
domain++;
}
len += i;
*((unsigned short *)(data)) = qtype;
data += 2;
len += 2;
*((unsigned short *)(data)) = qclass;
data += 2;
len += 2;
return dns_rr_add_end(packet, DNS_RR_QD, len);
}
int dns_add_A(struct dns_packet *packet, char *domain, int qtype, int qclass)
{
int maxlen = 0;
int i;
int len = 0;
unsigned char *data = dns_rr_add_start(packet, &maxlen);
unsigned char *data_ptr = data;
if (data == NULL) {
return -1;
}
return dns_rr_add_end(packet, DNS_RR_AN, len);
}
int dns_add_AAAA(struct dns_packet *packet, char *domain, int qtype, int qclass)
{
int maxlen = 0;
int i;
int len = 0;
unsigned char *data = dns_rr_add_start(packet, &maxlen);
unsigned char *data_ptr = data;
if (data == NULL) {
return -1;
}
return dns_rr_add_end(packet, DNS_RR_AN, len);
}
int dns_get_domain(struct dns_rrs *rrs, char *domain, int maxsize, int *qtype, int *qclass)
{
int i = 0;
unsigned char *data = rrs->data;
for (i = 0; i < maxsize; i++) {
*domain = *data;
if (*data == '\0') {
domain++;
data++;
break;
}
*domain = *data;
domain++;
data++;
}
*qtype = *((unsigned short *)(data));
data += 2;
*qclass = *((unsigned short *)(data));
data += 2;
return 0;
}
int dns_decode_body(struct dns_packet *packet, unsigned char *data, int size)
{
struct dns_head *head = &packet->head;
int i = 0;
int len = 0;
int decode_len = 0;
int qtype = 0;
int qclass = 0;
char name[DNS_MAX_CNAME_LEN];
struct dns_head *head = &packet->head;
int i = 0;
int len = 0;
int decode_len = 0;
int qtype = 0;
int qclass = 0;
char name[DNS_MAX_CNAME_LEN];
if (head->nrcount || head->nscount || head->ancount) {
return -1;
}
if (head->nrcount || head->nscount || head->ancount) {
return -1;
}
for (i = 0; i < head->qdcount; i++) {
len = dns_decode_qd(data, size - decode_len, name, DNS_MAX_CNAME_LEN, &qtype, &qclass);
printf("QR: %d, domain: %s, qtype = %d, qclass = %d\n", head->qr, name, qtype, qclass);
decode_len += len;
data += len;
}
for (i = 0; i < head->qdcount; i++) {
len = dns_decode_qd(data, size - decode_len, name, DNS_MAX_CNAME_LEN, &qtype, &qclass);
if (dns_add_domain(packet, name, qtype, qclass) != 0) {
return -1;
}
head->qdcount--;
decode_len += len;
data += len;
}
return 0;
return 0;
}
int dns_decode(struct dns_packet *packet, unsigned char *data, int size)
{
struct dns_head *head = &packet->head;
int decode_len = 0;
int ret = 0;
struct dns_head *head = &packet->head;
int decode_len = 0;
int ret = 0;
decode_len = dns_decode_head(head, &data);
ret = dns_decode_body(packet, data, size - decode_len);
return ret;
decode_len = dns_decode_head(head, &data);
ret = dns_decode_body(packet, data, size - decode_len);
struct dns_rrs *rrs;
int count = 0;
int i = 0;
rrs = dns_rr_get_start(packet, DNS_RR_QD, &count);
for (i = 0; i < count && rrs; i++, rrs = dns_rr_get_next(packet, rrs)) {
char name[128];
int qclass = 0;
int qtype = 0;
dns_get_domain(rrs, name, 128, &qtype, &qclass);
printf("QR: %d, domain: %s, qtype = %d, qclass = %d\n", head->qr, name, qtype, qclass);
}
return ret;
}
int dns_packet_init(struct dns_packet *packet, int size)
{
memset(packet, 0, size);
packet->size = size;
return 0;
}
int dns_encode(unsigned char *data, int size, struct dns_packet *packet)
{
int rc;
int len = 0;
int rc;
int len = 0;
len = dns_encode_head(&data, &packet->head);
len = dns_encode_head(&data, &packet->head);
while (1) {
len = dns_encode_domain(data, size, "www.baidu.com");
data += len;
dns_write_short(&data, /*qType*/12);
dns_write_short(&data, /*qClass*/ 1);
}
while (1) {
len = dns_encode_domain(data, size, "www.baidu.com");
data += len;
dns_write_short(&data, /*qType*/ 12);
dns_write_short(&data, /*qClass*/ 1);
}
/*
/*
rc |= dns_encode_resource_records(packet->answers, data);
rc |= dns_encode_resource_records(packet->nameservers, data);
rc |= dns_encode_resource_records(packet->additional, data);
*/
return rc;
return rc;
}