libowfat/socket/scan_ip6.c

#include "scan.h"
#include "ip4.h"
#include "ip6.h"

/*
 * IPv6 addresses are really ugly to parse.
 * Syntax: (h = hex digit)
 *   1. hhhh:hhhh:hhhh:hhhh:hhhh:hhhh:hhhh:hhhh
 *   2. any number of 0000 may be abbreviated as "::", but only once
 *   3. The last two words may be written as IPv4 address
 */

unsigned int scan_ip6(const char *s,char ip[16])
{
  unsigned int i;
  unsigned int len=0;
  unsigned long u;

  char suffix[16];
  int prefixlen=0;
  int suffixlen=0;

  for (i=0; i<16; i++) ip[i]=0;

  for (;;) {
    if (*s == ':') {
      len++;
      if (s[1] == ':') {	/* Found "::", skip to part 2 */
	s+=2;
	len++;
	break;
      }
      s++;
    }
    i = scan_xlong(s,&u);
    if (!i) return 0;
    if (prefixlen==12 && s[i]=='.') {
      /* the last 4 bytes may be written as IPv4 address */
      i=ip4_scan(s,ip+12);
      if (i)
	return i+len;
      else
	return 0;
    }
    ip[prefixlen++] = (u >> 8);
    ip[prefixlen++] = (u & 255);
    s += i; len += i;
    if (prefixlen==16)
      return len;
  }

/* part 2, after "::" */
  for (;;) {
    if (*s == ':') {
      if (suffixlen==0)
	break;
      s++;
      len++;
    } else if (suffixlen!=0)
      break;
    i = scan_xlong(s,&u);
    if (!i) {
      len--;
      break;
    }
    if (suffixlen+prefixlen<=12 && s[i]=='.') {
      int j=ip4_scan(s,suffix+suffixlen);
      if (j) {
	suffixlen+=4;
	len+=j;
	break;
      } else
	prefixlen=12-suffixlen;	/* make end-of-loop test true */
    }
    suffix[suffixlen++] = (u >> 8);
    suffix[suffixlen++] = (u & 255);
    s += i; len += i;
    if (prefixlen+suffixlen==16)
      break;
  }
  for (i=0; i<suffixlen; i++)
    ip[16-suffixlen+i] = suffix[i];
  return len;
}

static long int fromhex(unsigned char c) {
  if (c>='0' && c<='9')
    return c-'0';
  else if (c>='A' && c<='F')
    return c-'A'+10;
  else if (c>='a' && c<='f')
    return c-'a'+10;
  return -1;
}

unsigned int scan_ip6_flat(const char *s,char ip[16])
{
  int i;
  for (i=0; i<16; i++) {
    int tmp;
    tmp=fromhex(*s++);
    if (tmp<0) return 0;
    ip[i]=tmp << 4;
    tmp=fromhex(*s++);
    if (tmp<0) return 0;
    ip[i]+=tmp;
  }
  return 32;
}