#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include "dns_construct.h"

#if 0	//CMC for alignment 8/3/2001
#define SET_UINT16_TO_N(buf, val, count) *(uint16*)buf = htons(val);count += 2; buf += 2
#define SET_UINT32_TO_N(buf, val, count) *(uint32*)buf = htonl(val);count += 4; buf += 4
#else
#define SET_UINT16_TO_N(buf, val, count)		\
{	unsigned char	tmp[2], i;			\
	*(uint16*)&tmp = htons(val);			\
	for ( i = 0; i < 2; i++ )			\
		*((unsigned char *)buf+i) = tmp[i];	\
	count += 2; 					\
	buf += 2;					\
}
#define SET_UINT32_TO_N(buf, val, count)		\
{	unsigned char	tmp[4], i;			\
	*(uint32*)&tmp = htonl(val);			\
	for ( i = 0; i < 4; i++ )			\
		*((unsigned char *)buf+i) = tmp[i];	\
	count += 4; 					\
	buf += 4;					\
}
#endif
/*****************************************************************************/
/* this function encode the plain string in name to the domain name encoding
 * see decode_domain_name for more details on what this function does. */
int dns_construct_name(char *name, char *encoded_name)
{
  int i,j,k,n;

  k = 0; /* k is the index to temp */
  i = 0; /* i is the index to name */
  while( name[i] ){

	 /* find the dist to the next '.' or the end of the string and add it*/
	 for( j = 0; name[i+j] && name[i+j] != '.'; j++);
	 encoded_name[k++] = j;

	 /* now copy the text till the next dot */
	 for( n = 0; n < j; n++)
		encoded_name[k++] = name[i+n];

	 /* now move to the next dot */
	 i += j + 1;

	 /* check to see if last dot was not the end of the string */
	 if(!name[i-1])break;
  }
  encoded_name[k++] = 0;
  return k;
}
/*****************************************************************************/
int dns_construct_header(dns_request_t *m)
{
  char *ptr = m->original_buf;
  int dummy;

  SET_UINT16_TO_N( ptr, m->message.header.id, dummy );
  SET_UINT16_TO_N( ptr, m->message.header.flags.flags, dummy );
  SET_UINT16_TO_N( ptr, m->message.header.qdcount, dummy );
  SET_UINT16_TO_N( ptr, m->message.header.ancount, dummy );
  SET_UINT16_TO_N( ptr, m->message.header.nscount, dummy );
  SET_UINT16_TO_N( ptr, m->message.header.arcount, dummy );

  return 0;
}
/*****************************************************************************/
void dns_construct_reply( dns_request_t *m )
{
  int len;

  /* point to end of orginal packet */
  m->here = &m->original_buf[m->numread];

  m->message.header.ancount = 1;
  m->message.header.flags.f.question = 1;
//-----JYWeng: 20030530* modified this bit for palm
  m->message.header.flags.f.recursion_avail = 1;
//-----
  dns_construct_header( m );

  if( m->message.question[0].type == A ){
    /* standard lookup so return and IP */
    struct in_addr in;

    inet_aton( m->ip, &in );
    SET_UINT16_TO_N( m->here, 0xc00c, m->numread ); /* pointer to name */
    SET_UINT16_TO_N( m->here, A, m->numread );      /* type */
    SET_UINT16_TO_N( m->here, IN, m->numread );     /* class */
    SET_UINT32_TO_N( m->here, 10000, m->numread );  /* ttl */
    SET_UINT16_TO_N( m->here, 4, m->numread );      /* datalen */
    memcpy( m->here, &in.s_addr, sizeof(in.s_addr) ); /* data */
    m->numread += sizeof( in.s_addr);
  }else if ( m->message.question[0].type == PTR ){
    /* reverse look up so we are returning a name */
    SET_UINT16_TO_N( m->here, 0xc00c, m->numread ); /* pointer to name */
    SET_UINT16_TO_N( m->here, PTR, m->numread );    /* type */
    SET_UINT16_TO_N( m->here, IN, m->numread );     /* class */
    SET_UINT32_TO_N( m->here, 10000, m->numread );  /* ttl */
    len = dns_construct_name( m->cname, m->here + 2 );
    SET_UINT16_TO_N( m->here, len, m->numread );      /* datalen */
    m->numread += len;
  }
}
/*****************************************************************************/
void dns_construct_error_reply(dns_request_t *m)
{
  /* point to end of orginal packet */
  m->here = m->original_buf;

  m->message.header.flags.f.question = 1;
  m->message.header.flags.f.rcode = 2;
  dns_construct_header( m );
}