dns_sortip.c

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#include "byte.h"
#include "ip.h"
#include "dns.h"
 
/* XXX: sort servers by configurable notion of closeness? */
/* XXX: pay attention to competence of each server? */
/* XXX: pay attention to qualification (DNSSec, DNSCurve) of each server? */
/* YYY: we use a randomly sorted list of NS; not depending on answer */
 
void dns_sortip4(char *s,unsigned int n)
{
  unsigned int i;
  char tmp[4];
 
  n >>= 2;      /* 4 byte per IPv4 address */
  while (n > 1) {
    i = dns_random(n);
    --n;
    byte_copy(tmp,4,s + (i << 2));
    byte_copy(s + (i << 2),4,s + (n << 2));
    byte_copy(s + (n << 2),4,tmp);
  }
}
 
void dns_sortip6(char *s,unsigned int n)
{
  unsigned int i;
  char tmp[16];
 
  n >>= 4;      /* 16 byte per IPv4 address */
  while (n > 1) {
    i = dns_random(n);
    --n;
    byte_copy(tmp,16,s + (i << 4));
    byte_copy(s + (i << 4),16,s + (n << 4));
    byte_copy(s + (n << 4),16,tmp);
  }
}
 
int dns_uniqip4(const char *in,unsigned int n,char *out)
{
  unsigned int i, j, k, dup;
  byte_zero(out,n);
 
  for (i = k = 0; i < n; i += 4) { // all results
    dup = 0;
    for (j = 0; j <= k; j += 4)   // saved results
      if (byte_equal(out + j,4,in + i)) dup = 1;
    if (!dup) { byte_copy(out + k,4,in + i); k += 4; }
  }
 
  return k;
} 
 
int dns_uniqip6(const char *in,unsigned int n,char *out)
{
  unsigned int i, j, k, dup;
  byte_zero(out,n);
 
  for (i = k = 0; i < n; i += 16) { // all results
    dup = 0;
    for (j = 0; j <= k; j += 16)   // saved results
      if (byte_equal(out + j,16,in + i)) dup = 1;
    if (!dup) { byte_copy(out + k,16,in + i); k += 16; }
  }
 
  return k;
}