dns_dfd.c

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#include "error.h"
#include "alloc.h"
#include "byte.h"
#include "dns.h"
 
int dns_domain_fromdot(char **out,const char *buf,unsigned int n)
{
  char label[63];
  unsigned int labellen = 0; /* <= sizeof label */
  char name[255];
  unsigned int namelen = 0; /* <= sizeof name */
  char ch;
  char *x;
 
  errno = EPROTO;
 
  for (;;) {
    if (!n) break;
    ch = *buf++; --n;
    if (ch == '.') {
      if (labellen) {
        if (namelen + labellen + 1 > sizeof(name)) return 0;
        name[namelen++] = labellen;
        byte_copy(name + namelen,labellen,label);
        namelen += labellen;
        labellen = 0;
      }
      continue;
    }
    if (ch == '\\') {                  // octal -> decimal
      if (!n) break;
      ch = *buf++; --n;
      if ((ch >= '0') && (ch <= '7')) {
        ch -= '0';
        if (n && (*buf >= '0') && (*buf <= '7')) {
          ch <<= 3;
          ch += *buf - '0';
          ++buf; --n;
          if (n && (*buf >= '0') && (*buf <= '7')) {
            ch <<= 3;
            ch += *buf - '0';
            ++buf; --n;
          }
        }
      }
    }
    if (labellen >= sizeof(label)) return 0;
    label[labellen++] = ch;
  }
 
  if (labellen) {
    if (namelen + labellen + 1 > sizeof(name)) return 0;
    name[namelen++] = labellen;
    byte_copy(name + namelen,labellen,label);
    namelen += labellen;
    labellen = 0;
  }
 
  if (namelen + 1 > sizeof(name)) return 0;
  name[namelen++] = 0;
 
  x = alloc(namelen);
  if (!x) return DNS_MEM;
  byte_copy(x,namelen,name);
 
  if (*out) alloc_free(*out);
  *out = x;
  return 1;
}