src/network/dn_expand.c

   1 #include <resolv.h>
   2
   3 int __dn_expand(const unsigned char *base, const unsigned char *end, const unsigned char *src, char *dest, int space)
   4 {
   5         const unsigned char *p = src;
   6         char *dend, *dbegin = dest;
   7         int len = -1, i, j;
   8         if (p==end || space <= 0) return -1;
   9         dend = dest + (space > 254 ? 254 : space);
  10         /* detect reference loop using an iteration counter */
  11         for (i=0; i < end-base; i+=2) {
  12                 /* loop invariants: p<end, dest<dend */
  13                 if (*p & 0xc0) {
  14                         if (p+1==end) return -1;
  15                         j = ((p[0] & 0x3f) << 8) | p[1];
  16                         if (len < 0) len = p+2-src;
  17                         if (j >= end-base) return -1;
  18                         p = base+j;
  19                 } else if (*p) {
  20                         if (dest != dbegin) *dest++ = '.';
  21                         j = *p++;
  22                         if (j >= end-p || j >= dend-dest) return -1;
  23                         while (j--) *dest++ = *p++;
  24                 } else {
  25                         *dest = 0;
  26                         if (len < 0) len = p+1-src;
  27                         return len;
  28                 }
  29         }
  30         return -1;
  31 }
  32
  33 weak_alias(__dn_expand, dn_expand);