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#include "dns.h"
#include "byte.h"
#include "uint16.h"
#include "response.h"
char response[65535];
unsigned int response_len = 0; /* <= 65535 */
static unsigned int tctarget;
#define NAMES 100
static char name[NAMES][128];
static unsigned int name_ptr[NAMES]; /* each < 16384 */
static unsigned int name_num;
int response_addbytes(const char *buf,unsigned int len)
{
if (len > 65535 - response_len) return 0;
byte_copy(response + response_len,len,buf);
response_len += len;
return 1;
}
int response_addname(const char *d)
{
unsigned int dlen;
unsigned int i;
char buf[2];
dlen = dns_domain_length(d);
while (*d) {
for (i = 0;i < name_num;++i)
if (dns_domain_equal(d,name[i])) {
uint16_pack_big(buf,49152 + name_ptr[i]);
return response_addbytes(buf,2);
}
if (dlen <= 128)
if (name_num < NAMES) {
byte_copy(name[name_num],dlen,d);
name_ptr[name_num] = response_len;
++name_num;
}
i = (unsigned char) *d;
++i;
if (!response_addbytes(d,i)) return 0;
d += i;
dlen -= i;
}
return response_addbytes(d,1);
}
int response_query(const char *q,const char qtype[2],const char qclass[2])
{
response_len = 0;
name_num = 0;
if (!response_addbytes("\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 unsigned int dpos;
static int flaghidettl = 0;
void response_hidettl(void)
{
flaghidettl = 1;
}
int response_rstart(const char *d,const char type[2],uint32 ttl)
{
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;
uint32_pack_big(ttlstr,ttl);
if (!response_addbytes(ttlstr,4)) return 0;
if (!response_addbytes("\0\0",2)) return 0;
dpos = response_len;
return 1;
}
void response_rfinish(int x)
{
uint16_pack_big(response + dpos - 2,response_len - dpos);
if (!++response[x + 1]) ++response[x];
}
int response_cname(const char *c,const char *d,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 char id[2])
{
byte_copy(response,2,id);
}
void response_tc(void)
{
response[2] |= 2;
response_len = tctarget;
}
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