Listing 1.7
Reading/Writing Question Records

/* Query Type */
#define QTYPE_NB      0x0020  /* Name Query     */
#define QTYPE_NBSTAT  0x0021  /* Adapter Status */

/* Query Class */
#define QCLASS_IN     0x0001  /* Internet Class */

#include <string.h>     /* For memcpy() */
#include <netinet/in.h> /* htons(), ntohs(), etc. */

#include "NS_Qrec.h"


int Put_Qrec( uchar       *dst,
              const uchar *name,
              const uchar  pad,
              const uchar  sfx,
              const uchar *scope,
              const ushort qtype )
  /* ---------------------------------------------------- **
   * Store the fully encoded NBT name in the destination
   * buffer.  Also write the QUERY_TYPE and QUERY_CLASS
   * values.
   * ---------------------------------------------------- **
   */
  {
  int    len;
  ushort tmp;
  ushort qclass_in;

  qclass_in = htons( QCLASS_IN );

  /* Validate the qtype. */
  if( (QTYPE_NB != qtype)
   && (QTYPE_NBSTAT != qtype ) )
    return( -1 );

  len = L2_Encode( dst, name, pad, sfx, scope );
  if( len < 0 )
    return( len );

  tmp = htons( qtype );
  (void)memcpy( &(dst[len]), &tmp, 2 );
  len += 2;

  (void)memcpy( &(dst[len]), &qclass_in, 2 );
  return( len + 2 );
  } /* Put_Qrec */

ushort Get_Qtype( const uchar *qrec, int offset )
  /* ---------------------------------------------------- **
   * Read the QUERY_TYPE field from a query record.
   * Note that the offset parameter can be derived using
   * L2_Decode() function in listing 1.4.  Either that,
   * or use 1+strlen( qrec ).
   * ---------------------------------------------------- **
   */
  {
  ushort tmp;

  /* Read the two bytes from the packet.
   */
  tmp  = (ushort)(qrec[offset]) * 256;
  tmp |= qrec[1+offset];

  /* Convert to host byte order and return. */
  return( ntohs( tmp ) );
  } /* Get_Qtype */

$Revision: 1.10 $ $Date: 2003/02/18 21:43:58 $

Copyright © 1999-2003 Christopher R. Hertel  Released under the terms of the LGPL