github.com/afumu/libc@v0.0.6/musl/src/network/res_mkquery.c (about) 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[3] = 32; /* AD */ 24 q[5] = 1; 25 memcpy((char *)q+13, dname, l); 26 for (i=13; q[i]; i=j+1) { 27 for (j=i; q[j] && q[j] != '.'; j++); 28 if (j-i-1u > 62u) return -1; 29 q[i-1] = j-i; 30 } 31 q[i+1] = type; 32 q[i+3] = class; 33 34 /* Make a reasonably unpredictable id */ 35 clock_gettime(CLOCK_REALTIME, &ts); 36 id = ts.tv_nsec + ts.tv_nsec/65536UL & 0xffff; 37 q[0] = id/256; 38 q[1] = id; 39 40 memcpy(buf, q, n); 41 return n; 42 } 43 44 weak_alias(__res_mkquery, res_mkquery);