serverok.c

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#include <sys/types.h>
#include <sys/stat.h>
#include "byte.h"
#include "stralloc.h"
#include "serverok.h"
#include "ip.h"
#include "query.h"
 
static char fnserver[4 + IPFMT];
static char fncurve[4 + IPFMT];
static char fnedns0[4 + IPFMT];
static char fnctxtq[4 + IPFMT];
 
/*  To invoke 'serverok' $FLAGSERVER has to be set!
 
   -1 no curve server
   -2 toggle DNSCurve native/txt format (flagusetxtformat)
    1 omitt server
    2 toggle EDNS0 option (flagedns0)
*/
 
int serverok(char ip[16])
{
  struct stat st;
 
  fnserver[0] = fncurve[0] = fnctxtq[0] = fnedns0[0] = 'i';
  fnserver[1] = fncurve[1] = fnctxtq[1] = fnedns0[1] = 'p';
  fnserver[2] = fncurve[2] = fnctxtq[2] = fnedns0[2] = '/';
 
  fnserver[3] = '%'; // ommit NS (commented out)
  fncurve[3]  = '-'; // no DNSCurve NS, + => DNSCurve, - => std 
  fnctxtq[3]  = '*'; // toggle $USETXTFORMAT (DNSCurve only)
  fnedns0[3]  = '~'; // toggle $DNSOPTRR (EDNS0)
 
  if (byte_equal(ip,12,V4mappedprefix)) {
    fnserver[4 + ip4_fmt(fnserver + 4,ip + 12)] = 0;
    fncurve[4 + ip4_fmt(fncurve + 4,ip + 12)] = 0;
    fnedns0[4 + ip4_fmt(fnedns0 + 4,ip + 12)] = 0;
    fnctxtq[4 + ip4_fmt(fnctxtq + 4,ip + 12)] = 0;
  } else {
    fnserver[4 + ip6_fmt(fnserver + 4,ip)] = 0;
    fncurve[4 + ip6_fmt(fncurve + 4,ip)] = 0;
    fnedns0[4 + ip6_fmt(fnedns0 + 4,ip)] = 0;
    fnctxtq[4 + ip6_fmt(fnctxtq + 4,ip)] = 0;
  }
  
  if (stat(fnedns0,&st) == 0) return 2;
  if (stat(fnserver,&st) == 0) return 1;
  if (stat(fncurve,&st) == 0) return -1;
  if (stat(fnctxtq,&st) == 0) return -2;
 
  return 0;
}