lib/ipv4.c

   1 /*
   2  *      BIRD Library -- IPv4 Address Manipulation Functions
   3  *
   4  *      (c) 1998 Martin Mares <mj@ucw.cz>
   5  *
   6  *      Can be freely distributed and used under the terms of the GNU GPL.
   7  */
   8
   9 #include <stdlib.h>
  10
  11 #include "nest/bird.h"
  12 #include "lib/ip.h"
  13 #include "lib/string.h"
  14
  15 int
  16 ipv4_classify(u32 a)
  17 {
  18   u32 b = a >> 24U;
  19
  20   if (b && b <= 0xdf)
  21     {
  22       if (b == 0x7f)
  23         return IADDR_HOST | SCOPE_HOST;
  24       else if (b == 0x0a ||
  25                (a & 0xffff0000) == 0xc0a80000 ||
  26                (a & 0xfff00000) == 0xac100000)
  27         return IADDR_HOST | SCOPE_SITE;
  28       else
  29         return IADDR_HOST | SCOPE_UNIVERSE;
  30     }
  31   if (b >= 0xe0 && b <= 0xef)
  32     return IADDR_MULTICAST | SCOPE_UNIVERSE;
  33   if (a == 0xffffffff)
  34     return IADDR_BROADCAST | SCOPE_LINK;
  35   return IADDR_INVALID;
  36 }
  37
  38 char *
  39 ip_ntop(ip_addr a, char *b)
  40 {
  41   u32 x = _I(a);
  42
  43   return b + bsprintf(b, "%d.%d.%d.%d",
  44                       ((x >> 24) & 0xff),
  45                       ((x >> 16) & 0xff),
  46                       ((x >> 8) & 0xff),
  47                       (x & 0xff));
  48 }
  49
  50 char *
  51 ip_ntox(ip_addr a, char *b)
  52 {
  53   return b + bsprintf(b, "%08x", _I(a));
  54 }
  55
  56 u32
  57 ipv4_class_mask(u32 a)
  58 {
  59         u32 m;
  60
  61         if (a < 0x80000000)
  62                 m = 0xff000000;
  63         else if (a < 0xc0000000)
  64                 m = 0xffff0000;
  65         else
  66                 m = 0xffffff00;
  67         while (a & ~m)
  68                 m |= m >> 1;
  69         return m;
  70 }
  71
  72 int
  73 ip_pton(char *a, ip_addr *o)
  74 {
  75   int i;
  76   unsigned long int l;
  77   u32 ia = 0;
  78
  79   i=4;
  80   while (i--)
  81     {
  82       char *d, *c = strchr(a, '.');
  83       if (!c != !i)
  84         return 0;
  85       l = strtoul(a, &d, 10);
  86       if (d != c && *d || l > 255)
  87         return 0;
  88       ia = (ia << 8) | l;
  89       if (c)
  90         c++;
  91       a = c;
  92     }
  93   *o = ipa_from_u32(ia);
  94   return 1;
  95 }
  96
  97 byte *
  98 ipv4_skip_header(byte *pkt, int *len)
  99 {
 100   int l = *len;
 101   int q;
 102
 103   if (l < 20 || (*pkt & 0xf0) != 0x40)
 104     return NULL;
 105   q = (*pkt & 0x0f) * 4;
 106   if (q > l)
 107     return NULL;
 108   *len -= q;
 109   return pkt + q;
 110 }