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#include "dns.h"
#include "byte.h"
#include "crypto_uint16.h"
#include "crypto_uint32.h"
#include "response.h"
unsigned char response[65535];
long long response_len = 0; /* <= 65535 */
static long long tctarget;
#define NAMES 100
static unsigned char name[NAMES][255];
static long long name_ptr[NAMES]; /* each < 16384 */
static long long name_num;
int response_addbytes(const unsigned char *buf, long long len) {
if (len < 0) return 0;
if (len > 65535 - response_len) return 0;
byte_copy(response + response_len, len, buf);
response_len += len;
return 1;
}
int response_addname(const unsigned char *d) {
long long dlen;
long long i;
unsigned char buf[2];
dlen = dns_domain_length(d);
while (*d) {
for (i = 0; i < name_num; ++i)
if (dns_domain_equal(d, name[i])) {
crypto_uint16_store_bigendian(buf, 49152 + name_ptr[i]);
return response_addbytes(buf, 2);
}
if ((dlen <= 255) && (response_len < 16384))
if (name_num < NAMES) {
byte_copy(name[name_num], dlen, d);
name_ptr[name_num] = response_len;
++name_num;
}
i = *d;
++i;
if (!response_addbytes(d, i)) return 0;
d += i;
dlen -= i;
}
return response_addbytes(d, 1);
}
int response_query(const unsigned char *q, const unsigned char qtype[2], const unsigned char qclass[2]) {
response_len = 0;
name_num = 0;
if (!response_addbytes((unsigned char *)"\0\0\201\200\0\1\0\0\0\0\0\0", 12)) return 0;
if (!response_addname(q)) return 0;
if (!response_addbytes(qtype, 2)) return 0;
if (!response_addbytes(qclass, 2)) return 0;
tctarget = response_len;
return 1;
}
static long long dpos;
static int flaghidettl = 0;
void response_hidettl(void) {
flaghidettl = 1;
}
int response_rstart(const unsigned char *d, const unsigned char type[2], crypto_uint32 ttl) {
unsigned char ttlstr[4];
if (!response_addname(d)) return 0;
if (!response_addbytes(type, 2)) return 0;
if (!response_addbytes(DNS_C_IN, 2)) return 0;
if (flaghidettl) ttl = 0;
crypto_uint32_store_bigendian(ttlstr, ttl);
if (!response_addbytes(ttlstr, 4)) return 0;
if (!response_addbytes((unsigned char *)"\0\0", 2)) return 0;
dpos = response_len;
return 1;
}
void response_rfinish(int x) {
crypto_uint16_store_bigendian(response + dpos - 2, response_len - dpos);
if (!++response[x + 1]) ++response[x];
}
int response_cname(const unsigned char *c, const unsigned char *d, crypto_uint32 ttl) {
if (!response_rstart(c, DNS_T_CNAME, ttl)) return 0;
if (!response_addname(d)) return 0;
response_rfinish(RESPONSE_ANSWER);
return 1;
}
void response_nxdomain(void) {
response[3] |= 3;
response[2] |= 4;
}
void response_servfail(void) {
response[3] |= 2;
}
void response_id(const unsigned char id[2]) {
byte_copy(response, 2, id);
}
void response_tc(void) {
response[2] |= 2;
response_len = tctarget;
byte_zero(response + 6, 6);
}
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