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/**********************************************************
SixXS - Automatic IPv6 Connectivity Configuration Utility
***********************************************************
Copyright 2003-2005 SixXS - http://www.sixxs.net
***********************************************************
common/resolver.c - Simple DNS RR lookup function
***********************************************************
$Author: jeroen $
$Id: resolver.c,v 1.3 2006-07-23 14:13:57 jeroen Exp $
$Date: 2006-07-23 14:13:57 $
**********************************************************/
#include <stdlib.h>
#include <errno.h>
#include <stdio.h>
#include <string.h>
#include "resolver.h"
#ifndef _WIN32
#include <unistd.h>
#include <netinet/in.h>
#include <arpa/nameser.h>
#include <resolv.h>
#include <netdb.h>
int getrrs(const char *label, int rrtype, void gotrec(unsigned int num, int type, const char *record))
{
#ifdef _LINUX
struct __res_state res;
#endif
unsigned char answer[8192];
HEADER *header = (HEADER *)answer;
char buf[2048];
int ret, count;
unsigned int i,j,k,rrnum = 0;
unsigned char *startptr, *endptr, *ptr;
uint16_t type = 0, class = 0;
uint32_t ttl = 0;
#ifdef _LINUX
memset(&res, 0, sizeof(res));
res.options = RES_DEBUG;
res_ninit(&res);
#else
res_init();
#endif
memset(answer, 0, sizeof(answer));
#ifdef _LINUX
ret = res_nquery(&res, label, C_IN, rrtype, answer, sizeof(answer));
#else
ret = res_query(label, C_IN, rrtype, answer, sizeof(answer));
#endif
if (ret < 0) return -1;
/* Our start and end */
startptr = &answer[0];
endptr = &answer[ret];
/* Skip the header */
ptr = startptr + HFIXEDSZ;
/* Skip Query part */
for (count = ntohs(header->qdcount); count--; ptr += ret + QFIXEDSZ)
{
if ((ret = dn_skipname(ptr, endptr)) < 0) return -1;
}
/* Only look at the Answer section */
count = ntohs(header->ancount);
/* Go through all the Answer records */
while (ptr < endptr && count > 0)
{
rrnum++;
memset(buf, 0, sizeof(buf));
ret = dn_expand (startptr, endptr, ptr, buf, sizeof(buf));
if (ret < 0) break;
ptr += ret;
if (ptr + INT16SZ + INT16SZ + INT32SZ >= endptr) break;
/* Get the type */
NS_GET16(type, ptr);
/* Get the class */
NS_GET16(class, ptr);
/* Get the TTL */
NS_GET32(ttl, ptr);
/* Get the RDLength */
NS_GET16(ret, ptr);
memset(buf, 0, sizeof(buf));
switch (type)
{
case T_TXT:
for (k = ret, j = 0; j < k && &ptr[j] < endptr; j += (i+1))
{
i = ptr[j];
memcpy(buf, &ptr[j+1], i > sizeof(buf) ? sizeof(buf) : i);
buf[i > sizeof(buf) ? sizeof(buf) : i] = '\0';
if (rrtype == type || rrtype == T_ANY) gotrec(rrnum, type, buf);
}
break;
case T_A:
inet_ntop(AF_INET, ptr, buf, sizeof(buf));
if (rrtype == type || rrtype == T_ANY) gotrec(rrnum, type, buf);
break;
case T_AAAA:
inet_ntop(AF_INET6, ptr, buf, sizeof(buf));
if (rrtype == type || rrtype == T_ANY) gotrec(rrnum, type, buf);
break;
case T_MX:
/* Get the MX preference */
NS_GET16(ttl, ptr);
ret = dn_expand(startptr, endptr, ptr, buf, sizeof(buf));
if (rrtype == type || rrtype == T_ANY) gotrec(rrnum, type, buf);
break;
case T_NS:
ret = dn_expand(startptr, endptr, ptr, buf, sizeof(buf));
if (rrtype == type || rrtype == T_ANY) gotrec(rrnum, type, buf);
break;
default:
/* Unhandled */
break;
}
ptr += ret;
count--;
}
return 0;
}
#else
/*
* Windows Resolver Code, as per:
* http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dns/dns/dnsquery.asp
* http://support.microsoft.com/default.aspx?scid=kb%3Ben-us%3B831226
*/
#include <windns.h>
int getrrs(const char *label, int rrtype, void gotrec(unsigned int num, int type, const char *record))
{
DNS_STATUS status; /* Return value of DnsQuery_A() function */
PDNS_RECORD pResult, pRec; /* Pointer to DNS_RECORD structure */
unsigned int rrnum = 0, i;
uint16_t type;
status = DnsQuery(label, /* Pointer to OwnerName */
rrtype, /* Type of the record to be queried */
DNS_QUERY_STANDARD, /* Standard Query */
NULL, /* Contains DNS server IP address */
&pResult, /* Resource record that contains the response */
NULL); /* Reserved for future use */
if (status) return -1;
else
{
for (pRec = pResult; pRec; pRec = pRec->pNext)
{
rrnum++;
type = pRec->wType;
if (rrtype != type && rrtype != ns_t_any) continue;
switch (type)
{
case ns_t_txt:
for (i=0; i < pRec->Data.TXT.dwStringCount; i++)
{
gotrec(rrnum, type, pRec->Data.TXT.pStringArray[i]);
}
break;
case ns_t_a:
gotrec(rrnum, type, (const char *)&pRec->Data.A.IpAddress);
break;
case ns_t_aaaa:
gotrec(rrnum, type, (const char *)&pRec->Data.AAAA.Ip6Address);
break;
case ns_t_mx:
gotrec(rrnum, type, pRec->Data.MX.pNameExchange);
break;
case ns_t_ns:
gotrec(rrnum, type, pRec->Data.NS.pNameHost);
break;
}
}
}
/* Free memory allocated for DNS records. */
DnsRecordListFree(pResult, DnsFreeRecordListDeep);
return 0;
}
#endif
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