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61 lines
1.5 KiB
C
61 lines
1.5 KiB
C
#include <errno.h>
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#include "stralloc.h"
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#include "uint16.h"
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#include "byte.h"
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#include "dns.h"
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int dns_txt_packet(stralloc *out,const char *buf,unsigned int len)
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{
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unsigned int pos;
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char header[12];
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uint16 numanswers;
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uint16 datalen;
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char ch;
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unsigned int txtlen;
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int i;
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if (!stralloc_copys(out,"")) return -1;
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pos = dns_packet_copy(buf,len,0,header,12); if (!pos) return -1;
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uint16_unpack_big(header + 6,&numanswers);
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pos = dns_packet_skipname(buf,len,pos); if (!pos) return -1;
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pos += 4;
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while (numanswers--) {
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pos = dns_packet_skipname(buf,len,pos); if (!pos) return -1;
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pos = dns_packet_copy(buf,len,pos,header,10); if (!pos) return -1;
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uint16_unpack_big(header + 8,&datalen);
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if (byte_equal(header,2,DNS_T_TXT))
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if (byte_equal(header + 2,2,DNS_C_IN)) {
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if (pos + datalen > len) { errno = EINVAL; return -1; }
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txtlen = 0;
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for (i = 0;i < datalen;++i) {
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ch = buf[pos + i];
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if (!txtlen)
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txtlen = (unsigned char) ch;
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else {
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--txtlen;
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if (ch < 32) ch = '?';
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if (ch > 126) ch = '?';
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if (!stralloc_append(out,&ch)) return -1;
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}
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}
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}
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pos += datalen;
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}
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return 0;
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}
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static char *q = 0;
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int dns_txt(stralloc *out,const stralloc *fqdn)
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{
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if (!dns_domain_fromdot(&q,fqdn->s,fqdn->len)) return -1;
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if (dns_resolve(q,DNS_T_TXT) == -1) return -1;
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if (dns_txt_packet(out,dns_resolve_tx.packet,dns_resolve_tx.packetlen) == -1) return -1;
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dns_transmit_free(&dns_resolve_tx);
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dns_domain_free(&q);
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return 0;
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}
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