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dns_proto.h

/* ----------------------------------------------------------------------------
 *
    VDE_OVER_NS 
      (C) 2007 Daniele Lacamera

    Derived from:
    NSTX -- tunneling network-packets over DNS

     (C) 2000 by Florian Heinz and Julien Oster

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License version 2, as 
    published by the Free Software Foundation.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

  -------------------------------------------------------------------------- */

#ifndef NSTX_DNS_H
#define NSTX_DNS_H
struct dnsqueryhdr {
  unsigned short id;

/* be careful with that!
 * this version is documented as the LITTLE endian version, however our
 * processors are having a BIG endian byte order!
 *
 * The solution is simple (but did take as some stressy hours to find):
 * this is NOT the byte order, it is the BIT order!
 *
 * And as most processors (except some very rare ones including the DEC
 * PDP machines) we are having a little endian bit order.
 *
 * So if you are reading something about endianess in this context,
 * be careful if it says BYTE order or BIT order! On Intel processors, for
 * example, byte order is big endian, while bit order is little endian.
 *
 * For additional confusion: RFC1035 really shows the headers in the very
 * uncommon big endian bit order.
 *
 * In the only intention to drive you completely mad: at least in Linux the
 * header-file <arpa/nameser.h> talks about a little endian BYTE order for
 * our working version. Ugh. Anyway, it clearly works this way, and that
 * proves the correctness of my assumption.
 *
 * -- frodo
 */

  unsigned char rd:1;
  unsigned char tc:1;
  unsigned char aa:1;
  unsigned char opcode:4;
  unsigned char qr:1;
  unsigned char rcode:4;
  unsigned char z:3;
  unsigned char ra:1;

  unsigned short qdcount;
  unsigned short ancount;
  unsigned short nscount;
  unsigned short arcount;
#define DNSOP_QUERY 0
#define DNSOP_IQUERY 1
#define DNSOP_STATUS 2
};

struct dnsquestion {
  unsigned char qname[48];
  unsigned short qtype;
  unsigned short qclass;
};

struct dnsanswer {
  unsigned short type;
  unsigned short class;
  unsigned int ttl;
  // unsigned short rdlength;
};


struct dnstxtanswer {
  unsigned char name[256];
};


#define NSTYPE_TXT 0x0010

struct ns_answer_header {
      u_int16_t type;
      u_int16_t clas;
      u_int32_t ttl;
      u_int16_t datalen;
}
 __attribute__((packed));

struct ns_transaction_header {
      u_int16_t tid;
      u_int16_t flags;
      u_int16_t questions;
      u_int16_t answers;
      u_int16_t authority;
      u_int16_t additional;
      
}
 __attribute__((packed));


/* overall functions */


/* client functions */

int nstxc_dns_init (struct sockaddr *, socklen_t,
                struct sockaddr *, socklen_t);
int nstxc_dns_query (char *, unsigned short);


#endif /*NSTX_DNS_H*/

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