ip4_bit.c

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/***
  @file ip4_bit.c
  @author Jens Wehrenbrecht, feh
  @funcs ip4_bitstring, bitstring_ip4
*/
#include "ip.h"
#include "byte.h"
#include "scan.h"
#include "str.h"
#include "fmt.h"
#include "ip_bit.h"
 
#define BITSUBSTITUTION
 
static char strnum[FMT_ULONG];
 
/***
  /fn ip4_bitstring
  /brief This function converts a IPv4 address into its binary representation with given prefix len
  /param out: ip4string    0-terminated destination address.
  /param in:  ip4address   The source address.
  /param in:  prefix       The net prefix bits (maximum 32 bits for IPv4).
  /return -1: lack of memory;  1: non valid IP address; 0: successful converted.
*/
 
int ip4_bitstring(stralloc *ip4string, char *ip, unsigned int prefix)
{
  int i, j;
  char ip4[4];
  int count = 0;
  unsigned char number;
#ifdef BITSUBSTITUTION
  const char *letterarray = "abcdefghijklmnopqrstuvwxyz123456";
#endif
 
  if (!stralloc_copys(ip4string,"")) return -1;
  if (!stralloc_readyplus(ip4string,32)) return -1;
  ip4_scan(ip,ip4);
 
  for (i = 0; i < 4; i++) {
    number = (unsigned char) ip4[i];
    for (j = 7; j >= 0; j--) {
      if (number & (1<<j)) {
#ifdef BITSUBSTITUTION
        if (!stralloc_catb(ip4string,letterarray + count,1)) return -1;
#else
        if (!stralloc_cats(ip4string,"1")) return -1;
#endif
      } else {
        if (!stralloc_cats(ip4string,"0")) return -1;
      }
      count++;
      prefix--;
      if (prefix == 0) return 0;
    }
  }
 
  return 1;
}
 
/***
  /fn bitstring_ip4
  /brief This function takes an IPv4 bitstring and translates it to an IPv4 address + prefix
  /param in:  ip4string    The source address  (with '_' start token).
  /param out: ip4addr      0-terminated estination IPv4 address + net prefix (eg. 127.0.0.0/16).
  /return -1: lack of memory;  1: non valid IPv4 address; 0: successful converted.
*/
 
int bitstring_ip4(stralloc *ip4addr, stralloc *ip4string)
{
  int j;
  int num = 0;
  int value = 256;
  int prefix; 
 
  if (!stralloc_copys(ip4addr,"")) return -1;
  prefix = ip4string->len - 1;
 
  if (prefix <= 0) return 1;
  if (prefix <= 1 || prefix > 32) return 1;
 
  for (j = 1; j <= prefix; j++) {
   if (ip4string->s[j] != '0') {
      num += (value/2); 
      value /= 2;
    } else 
      value /= 2; 
    if (j % 8 == 0 || j == prefix) {
      if (!stralloc_catb(ip4addr,strnum,fmt_ulong(strnum,num))) return -1;
      if (j < 32) if (!stralloc_cats(ip4addr,".")) return -1;
      num = 0;
      value = 256;
    }
  }
  
  if (!stralloc_cats(ip4addr,"/")) return -1;
  if (!stralloc_catb(ip4addr,strnum,fmt_ulong(strnum,prefix))) return -1;
  if (!stralloc_0(ip4addr)) return -1;
 
  return 0;
}