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#include "byte.h"
#include "dnsresolv.h"
#include "stralloc.h"
#include "uint_t.h"
/**
@file dns_txt.c
@authors djb, fefe, feh
@ref ucspi-tcp
@brief DNS text query (txt)
*/
int dns_txt_packet(stralloc *out, const char *buf, unsigned int len)
{
unsigned int pos;
char header[12];
uint16 numanswers;
uint16 datalen;
char ch;
unsigned int txtlen;
int i;
int ranswers = 0;
if (!stralloc_copys(out, "")) return DNS_MEM;
pos = dns_packet_copy(buf, len, 0, header, 12);
if (!pos) return DNS_ERR;
uint16_unpack_big(header + 6, &numanswers);
pos = dns_packet_skipname(buf, len, pos);
if (!pos) return DNS_ERR;
pos += 4;
while (numanswers--) {
pos = dns_packet_skipname(buf, len, pos);
if (!pos) return DNS_ERR;
pos = dns_packet_copy(buf, len, pos, header, 10);
if (!pos) return DNS_ERR;
uint16_unpack_big(header + 8, &datalen);
if (byte_equal(header, 2, DNS_T_TXT)) {
if (byte_equal(header + 2, 2, DNS_C_IN)) {
if (pos + datalen > len) return DNS_ERR;
txtlen = (unsigned char)buf[pos];
for (i = 1; i < datalen; ++i) {
ch = buf[pos + i];
if (i == txtlen + 1) // next label
txtlen += (unsigned char)ch + 1;
else {
if (ch < 32) ch = '?';
if (ch > 126) ch = '?';
if (!stralloc_append(out, &ch)) return DNS_MEM;
}
}
}
}
pos += datalen;
++ranswers;
if (numanswers)
if (!stralloc_append(out, "\n")) return DNS_MEM;
}
return ranswers;
}
static char *q = 0;
int dns_txt(stralloc *out, const stralloc *fqdn)
{
int rc;
if (dns_domain_fromdot(&q, fqdn->s, fqdn->len) <= 0) return DNS_ERR;
if (dns_resolve(q, DNS_T_TXT) < 0) return DNS_ERR;
if ((rc = dns_txt_packet(out, dns_resolve_tx.packet, dns_resolve_tx.packetlen)) < 0) return DNS_ERR;
dns_transmit_free(&dns_resolve_tx);
dns_domain_free(&q);
return rc;
}
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