update code
This commit is contained in:
Nick Peng
234
dns.c
234
dns.c
@@ -1,102 +1,222 @@
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#include "dns.h"
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#include <stdio.h>
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#include <string.h>
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#define DNS_MAX_CNAME_LEN 128
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int dns_decode_head(struct dns_head *head, struct idns_head *ihead)
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short dns_read_short(unsigned char **buffer)
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{
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head->id = ntohs(ihead->id);
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head->opcode = (ihead->opcode >> 3) & 0x0F;
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head->query = (ihead->opcode & 0x80) != 0x80;
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head->aa = (ihead->opcode & 0x04) == 0x04;
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head->tc = (ihead->opcode & 0x02) == 0x02;
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head->rd = (ihead->opcode & 0x01) == 0x01;
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head->ra = (ihead->rcode & 0x80) == 0x80;
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head->z = (ihead->rcode & 0x40) == 0x40;
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head->ad = (ihead->rcode & 0x20) == 0x20;
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head->cd = (ihead->rcode & 0x10) == 0x10;
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head->rcode = (ihead->rcode & 0x0F);
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head->qdcount = ntohs(ihead->qdcount);
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head->ancount = ntohs(ihead->ancount);
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head->nscount = ntohs(ihead->nscount);
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head->nrcount = ntohs(ihead->arcount);
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unsigned short value;
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value = *((unsigned short *)(*buffer));
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*buffer += 2;
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return ntohs(value);
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}
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void dns_write_char(unsigned char **buffer, unsigned char value)
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{
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**buffer = value;
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*buffer += 1;
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}
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unsigned char dns_read_char(unsigned char **buffer)
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{
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unsigned char value = **buffer;
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*buffer += 1;
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return value;
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}
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void dns_write_short(unsigned char **buffer, unsigned short value)
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{
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value = htons(value);
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*((unsigned short *)(*buffer)) = value;
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*buffer += 2;
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}
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void dns_write_int(unsigned char **buffer, unsigned int value)
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{
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value = htons(value);
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*((unsigned int *)(*buffer)) = value;
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*buffer += 4;
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}
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unsigned int dns_read_int(unsigned char **buffer)
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{
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unsigned int value;
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value = *((unsigned int *)(*buffer));
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*buffer += 4;
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return ntohs(value);
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}
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int dns_decode_head(struct dns_head *head, unsigned char **data)
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{
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unsigned int fields;
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unsigned char *start = *data;
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unsigned char *end = start;
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head->id = dns_read_short(data);
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fields = dns_read_short(data);
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head->qr = (fields & QR_MASK) >> 15;
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head->opcode = (fields & OPCODE_MASK) >> 11;
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head->aa = (fields & AA_MASK) >> 10;
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head->tc = (fields & TC_MASK) >> 9;
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head->rd = (fields & RD_MASK) >> 8;
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head->ra = (fields & RA_MASK) >> 7;
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head->rcode = (fields & RCODE_MASK) >> 0;
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head->qdcount = dns_read_short(data);
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head->ancount = dns_read_short(data);
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head->nscount = dns_read_short(data);
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head->nrcount = dns_read_short(data);
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end = *data;
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return start - end;
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}
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int dns_encode_head(unsigned char **data, struct dns_head *head)
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{
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dns_write_short(data, head->id);
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int fields = 0;
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fields |= (head->qr << 15) & QR_MASK;
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fields |= (head->rcode << 0) & RCODE_MASK;
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dns_write_short(data, fields);
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dns_write_short(data, head->qdcount);
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dns_write_short(data, head->ancount);
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dns_write_short(data, head->nscount);
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dns_write_short(data, head->nrcount);
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return 0;
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}
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int dns_decode_rr(char *data, int size)
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int dns_get_domain(char *output, int size, unsigned char *data)
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{
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int ret;
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int len = 0;
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int i = 0;
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int output_len = 0;
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int copy_len = 0;
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int total_len = 0;
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return len;
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}
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while (data[i]) {
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int len = data[i];
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int dns_get_domain(char *data, int size, char *output)
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{
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int i = 0;
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if (i != 0) {
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*output = '.';
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output++;
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}
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while (data[i]) {
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int len = data[i];
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*output = '.';
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output++;
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i++;
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memcpy(output, data + i, len);
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total_len++;
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if (output_len < size - 1) {
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copy_len = (len < size - output_len) ? len : size - 1 - output_len;
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memcpy(output, data + i, copy_len);
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}
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i += len;
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output += len;
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output_len += len;
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total_len += len;
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}
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int qtype = (unsigned short) data[i+1];
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int qclass = (unsigned short) data[i+3];
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return 0;
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*output = 0;
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total_len++;
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return total_len;
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}
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int dns_decode_qd(char *data, int size)
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int dns_encode_domain(unsigned char *output, int size, char *domain)
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{
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int i = 0;
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int num = 0;
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int total_len = 0;
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unsigned char *ptr_num = output++;
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total_len++;
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while (i < size && *domain != 0) {
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if (*domain == '.') {
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*ptr_num = num;
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num = 0;
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ptr_num = output;
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domain++;
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output++;
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total_len++;
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continue;
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}
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*output = *domain;
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num++;
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output++;
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domain++;
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total_len++;
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}
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*ptr_num = num;
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*output = 0;
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total_len++;
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return total_len;
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}
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int dns_decode_qd(unsigned char *data, int size, char *domain, int domain_size, int *qtype, int *qclass)
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{
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int ret;
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int len = 0;
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char name[DNS_MAX_CNAME_LEN];
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len = dns_get_domain(data, size, name);
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printf("%s\n", name);
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len = dns_get_domain(domain, domain_size, data);
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data += len;
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*qtype = dns_read_short(&data);
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*qclass = dns_read_short(&data);
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return len;
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}
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int dns_decode_body(struct dns_packet *packet, char *data, int size)
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int dns_decode_body(struct dns_packet *packet, unsigned char *data, int size)
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{
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struct dns_head *head = &packet->head;
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int i = 0;
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int len = 0;
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int decode_len = 0;
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int qtype = 0;
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int qclass = 0;
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char name[DNS_MAX_CNAME_LEN];
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if (head->nrcount || head->nscount || head->ancount) {
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return -1;
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}
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for (i = 0; i < head->qdcount; i++) {
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len = dns_decode_qd(data, size - decode_len);
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len = dns_decode_qd(data, size - decode_len, name, DNS_MAX_CNAME_LEN, &qtype, &qclass);
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printf("QR: %d, domain: %s, qtype = %d, qclass = %d\n", head->qr, name, qtype, qclass);
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decode_len += len;
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data += len;
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}
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for (i = 0; i < head->qdcount; i++) {
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}
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for (i = 0; i < head->qdcount; i++) {
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}
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for (i = 0; i < head->qdcount; i++) {
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}
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return 0;
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}
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int dns_decode(struct dns_packet *packet, char *data, int size)
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int dns_decode(struct dns_packet *packet, unsigned char *data, int size)
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{
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struct idns_head *ihead = (struct idns_head *)data;
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struct dns_head *head = &packet->head;
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int decode_len = 0;
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int ret = 0;
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dns_decode_head(head, ihead);
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decode_len += sizeof(struct idns_head);
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data += sizeof(struct idns_head);
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dns_decode_body(packet, data, size - decode_len);
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return -1;
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decode_len = dns_decode_head(head, &data);
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ret = dns_decode_body(packet, data, size - decode_len);
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return ret;
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}
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int dns_encode(unsigned char *data, int size, struct dns_packet *packet)
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{
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int rc;
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int len = 0;
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len = dns_encode_head(&data, &packet->head);
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while (1) {
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len = dns_encode_domain(data, size, "www.baidu.com");
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data += len;
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dns_write_short(&data, /*qType*/12);
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dns_write_short(&data, /*qClass*/ 1);
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}
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/*
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rc |= dns_encode_resource_records(packet->answers, data);
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rc |= dns_encode_resource_records(packet->nameservers, data);
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rc |= dns_encode_resource_records(packet->additional, data);
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*/
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return rc;
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}
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