1#define _BSD_SOURCE
2#include <errno.h>
3#include <stddef.h>
4#include <resolv.h>
5#include <arpa/nameser.h>
6
7const struct _ns_flagdata _ns_flagdata[16] = {
8	{ 0x8000, 15 },
9	{ 0x7800, 11 },
10	{ 0x0400, 10 },
11	{ 0x0200, 9 },
12	{ 0x0100, 8 },
13	{ 0x0080, 7 },
14	{ 0x0040, 6 },
15	{ 0x0020, 5 },
16	{ 0x0010, 4 },
17	{ 0x000f, 0 },
18	{ 0x0000, 0 },
19	{ 0x0000, 0 },
20	{ 0x0000, 0 },
21	{ 0x0000, 0 },
22	{ 0x0000, 0 },
23	{ 0x0000, 0 },
24};
25
26unsigned ns_get16(const unsigned char *cp)
27{
28	return cp[0]<<8 | cp[1];
29}
30
31unsigned long ns_get32(const unsigned char *cp)
32{
33	return (unsigned)cp[0]<<24 | cp[1]<<16 | cp[2]<<8 | cp[3];
34}
35
36void ns_put16(unsigned s, unsigned char *cp)
37{
38	*cp++ = s>>8;
39	*cp++ = s;
40}
41
42void ns_put32(unsigned long l, unsigned char *cp)
43{
44	*cp++ = l>>24;
45	*cp++ = l>>16;
46	*cp++ = l>>8;
47	*cp++ = l;
48}
49
50int ns_initparse(const unsigned char *msg, int msglen, ns_msg *handle)
51{
52	int i, r;
53
54	handle->_msg = msg;
55	handle->_eom = msg + msglen;
56	if (msglen < (2 + ns_s_max) * NS_INT16SZ) goto bad;
57	NS_GET16(handle->_id, msg);
58	NS_GET16(handle->_flags, msg);
59	for (i = 0; i < ns_s_max; i++) NS_GET16(handle->_counts[i], msg);
60	for (i = 0; i < ns_s_max; i++) {
61		if (handle->_counts[i]) {
62			handle->_sections[i] = msg;
63			r = ns_skiprr(msg, handle->_eom, i, handle->_counts[i]);
64			if (r < 0) return -1;
65			msg += r;
66		} else {
67			handle->_sections[i] = NULL;
68		}
69	}
70	if (msg != handle->_eom) goto bad;
71	handle->_sect = ns_s_max;
72	handle->_rrnum = -1;
73	handle->_msg_ptr = NULL;
74	return 0;
75bad:
76	errno = EMSGSIZE;
77	return -1;
78}
79
80int ns_skiprr(const unsigned char *ptr, const unsigned char *eom, ns_sect section, int count)
81{
82	const unsigned char *p = ptr;
83	int r;
84
85	while (count--) {
86		r = dn_skipname(p, eom);
87		if (r < 0) goto bad;
88		if (r + 2 * NS_INT16SZ > eom - p) goto bad;
89		p += r + 2 * NS_INT16SZ;
90		if (section != ns_s_qd) {
91			if (NS_INT32SZ + NS_INT16SZ > eom - p) goto bad;
92			p += NS_INT32SZ;
93			NS_GET16(r, p);
94			if (r > eom - p) goto bad;
95			p += r;
96		}
97	}
98	return p - ptr;
99bad:
100	errno = EMSGSIZE;
101	return -1;
102}
103
104int ns_parserr(ns_msg *handle, ns_sect section, int rrnum, ns_rr *rr)
105{
106	int r;
107
108	if (section < 0 || section >= ns_s_max) goto bad;
109	if (section != handle->_sect) {
110		handle->_sect = section;
111		handle->_rrnum = 0;
112		handle->_msg_ptr = handle->_sections[section];
113	}
114	if (rrnum == -1) rrnum = handle->_rrnum;
115	if (rrnum < 0 || rrnum >= handle->_counts[section]) goto bad;
116	if (rrnum < handle->_rrnum) {
117		handle->_rrnum = 0;
118		handle->_msg_ptr = handle->_sections[section];
119	}
120	if (rrnum > handle->_rrnum) {
121		r = ns_skiprr(handle->_msg_ptr, handle->_eom, section, rrnum - handle->_rrnum);
122		if (r < 0) return -1;
123		handle->_msg_ptr += r;
124		handle->_rrnum = rrnum;
125	}
126	r = ns_name_uncompress(handle->_msg, handle->_eom, handle->_msg_ptr, rr->name, NS_MAXDNAME);
127	if (r < 0) return -1;
128	handle->_msg_ptr += r;
129	if (2 * NS_INT16SZ > handle->_eom - handle->_msg_ptr) goto size;
130	NS_GET16(rr->type, handle->_msg_ptr);
131	NS_GET16(rr->rr_class, handle->_msg_ptr);
132	if (section != ns_s_qd) {
133		if (NS_INT32SZ + NS_INT16SZ > handle->_eom - handle->_msg_ptr) goto size;
134		NS_GET32(rr->ttl, handle->_msg_ptr);
135		NS_GET16(rr->rdlength, handle->_msg_ptr);
136		if (rr->rdlength > handle->_eom - handle->_msg_ptr) goto size;
137		rr->rdata = handle->_msg_ptr;
138		handle->_msg_ptr += rr->rdlength;
139	} else {
140		rr->ttl = 0;
141		rr->rdlength = 0;
142		rr->rdata = NULL;
143	}
144	handle->_rrnum++;
145	if (handle->_rrnum > handle->_counts[section]) {
146		handle->_sect = section + 1;
147		if (handle->_sect == ns_s_max) {
148			handle->_rrnum = -1;
149			handle->_msg_ptr = NULL;
150		} else {
151			handle->_rrnum = 0;
152		}
153	}
154	return 0;
155bad:
156	errno = ENODEV;
157	return -1;
158size:
159	errno = EMSGSIZE;
160	return -1;
161}
162
163int ns_name_uncompress(const unsigned char *msg, const unsigned char *eom,
164                       const unsigned char *src, char *dst, size_t dstsiz)
165{
166	int r;
167	r = dn_expand(msg, eom, src, dst, dstsiz);
168	if (r < 0) errno = EMSGSIZE;
169	return r;
170}
171
172