xref: /aosp_15_r20/external/musl/src/network/res_mkquery.c (revision c9945492fdd68bbe62686c5b452b4dc1be3f8453)
1*c9945492SAndroid Build Coastguard Worker #include <resolv.h>
2*c9945492SAndroid Build Coastguard Worker #include <string.h>
3*c9945492SAndroid Build Coastguard Worker #include <time.h>
4*c9945492SAndroid Build Coastguard Worker 
__res_mkquery(int op,const char * dname,int class,int type,const unsigned char * data,int datalen,const unsigned char * newrr,unsigned char * buf,int buflen)5*c9945492SAndroid Build Coastguard Worker int __res_mkquery(int op, const char *dname, int class, int type,
6*c9945492SAndroid Build Coastguard Worker 	const unsigned char *data, int datalen,
7*c9945492SAndroid Build Coastguard Worker 	const unsigned char *newrr, unsigned char *buf, int buflen)
8*c9945492SAndroid Build Coastguard Worker {
9*c9945492SAndroid Build Coastguard Worker 	int id, i, j;
10*c9945492SAndroid Build Coastguard Worker 	unsigned char q[280];
11*c9945492SAndroid Build Coastguard Worker 	struct timespec ts;
12*c9945492SAndroid Build Coastguard Worker 	size_t l = strnlen(dname, 255);
13*c9945492SAndroid Build Coastguard Worker 	int n;
14*c9945492SAndroid Build Coastguard Worker 
15*c9945492SAndroid Build Coastguard Worker 	if (l && dname[l-1]=='.') l--;
16*c9945492SAndroid Build Coastguard Worker 	if (l && dname[l-1]=='.') return -1;
17*c9945492SAndroid Build Coastguard Worker 	n = 17+l+!!l;
18*c9945492SAndroid Build Coastguard Worker 	if (l>253 || buflen<n || op>15u || class>255u || type>255u)
19*c9945492SAndroid Build Coastguard Worker 		return -1;
20*c9945492SAndroid Build Coastguard Worker 
21*c9945492SAndroid Build Coastguard Worker 	/* Construct query template - ID will be filled later */
22*c9945492SAndroid Build Coastguard Worker 	memset(q, 0, n);
23*c9945492SAndroid Build Coastguard Worker 	q[2] = op*8 + 1;
24*c9945492SAndroid Build Coastguard Worker 	q[3] = 32; /* AD */
25*c9945492SAndroid Build Coastguard Worker 	q[5] = 1;
26*c9945492SAndroid Build Coastguard Worker 	memcpy((char *)q+13, dname, l);
27*c9945492SAndroid Build Coastguard Worker 	for (i=13; q[i]; i=j+1) {
28*c9945492SAndroid Build Coastguard Worker 		for (j=i; q[j] && q[j] != '.'; j++);
29*c9945492SAndroid Build Coastguard Worker 		if (j-i-1u > 62u) return -1;
30*c9945492SAndroid Build Coastguard Worker 		q[i-1] = j-i;
31*c9945492SAndroid Build Coastguard Worker 	}
32*c9945492SAndroid Build Coastguard Worker 	q[i+1] = type;
33*c9945492SAndroid Build Coastguard Worker 	q[i+3] = class;
34*c9945492SAndroid Build Coastguard Worker 
35*c9945492SAndroid Build Coastguard Worker 	/* Make a reasonably unpredictable id */
36*c9945492SAndroid Build Coastguard Worker 	clock_gettime(CLOCK_REALTIME, &ts);
37*c9945492SAndroid Build Coastguard Worker 	id = ts.tv_nsec + ts.tv_nsec/65536UL & 0xffff;
38*c9945492SAndroid Build Coastguard Worker 	q[0] = id/256;
39*c9945492SAndroid Build Coastguard Worker 	q[1] = id;
40*c9945492SAndroid Build Coastguard Worker 
41*c9945492SAndroid Build Coastguard Worker 	memcpy(buf, q, n);
42*c9945492SAndroid Build Coastguard Worker 	return n;
43*c9945492SAndroid Build Coastguard Worker }
44*c9945492SAndroid Build Coastguard Worker 
45*c9945492SAndroid Build Coastguard Worker weak_alias(__res_mkquery, res_mkquery);
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