src/network/res_mkquery.c

   1 #include <resolv.h>
   2 #include <string.h>
   3 #include <time.h>
   4
   5 int __res_mkquery(int op, const char *dname, int class, int type,
   6         const unsigned char *data, int datalen,
   7         const unsigned char *newrr, unsigned char *buf, int buflen)
   8 {
   9         int id, i, j;
  10         unsigned char q[280];
  11         struct timespec ts;
  12         size_t l = strnlen(dname, 255);
  13         int n;
  14
  15         if (l && dname[l-1]=='.') l--;
  16         n = 17+l+!!l;
  17         if (l>253 || buflen<n || op>15u || class>255u || type>255u)
  18                 return -1;
  19
  20         /* Construct query template - ID will be filled later */
  21         memset(q, 0, n);
  22         q[2] = op*8 + 1;
  23         q[5] = 1;
  24         memcpy((char *)q+13, dname, l);
  25         for (i=13; q[i]; i=j+1) {
  26                 for (j=i; q[j] && q[j] != '.'; j++);
  27                 if (j-i-1u > 62u) return -1;
  28                 q[i-1] = j-i;
  29         }
  30         q[i+1] = type;
  31         q[i+3] = class;
  32
  33         /* Make a reasonably unpredictable id */
  34         clock_gettime(CLOCK_REALTIME, &ts);
  35         id = ts.tv_nsec + ts.tv_nsec/65536UL & 0xffff;
  36         q[0] = id/256;
  37         q[1] = id;
  38
  39         memcpy(buf, q, n);
  40         return n;
  41 }
  42
  43 weak_alias(__res_mkquery, res_mkquery);