1 | #define _BSD_SOURCE
|
---|
2 | #include <errno.h>
|
---|
3 | #include <stddef.h>
|
---|
4 | #include <resolv.h>
|
---|
5 | #include <arpa/nameser.h>
|
---|
6 |
|
---|
7 | const 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 |
|
---|
26 | unsigned ns_get16(const unsigned char *cp)
|
---|
27 | {
|
---|
28 | return cp[0]<<8 | cp[1];
|
---|
29 | }
|
---|
30 |
|
---|
31 | unsigned long ns_get32(const unsigned char *cp)
|
---|
32 | {
|
---|
33 | return (unsigned)cp[0]<<24 | cp[1]<<16 | cp[2]<<8 | cp[3];
|
---|
34 | }
|
---|
35 |
|
---|
36 | void ns_put16(unsigned s, unsigned char *cp)
|
---|
37 | {
|
---|
38 | *cp++ = s>>8;
|
---|
39 | *cp++ = s;
|
---|
40 | }
|
---|
41 |
|
---|
42 | void 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 |
|
---|
50 | int 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;
|
---|
75 | bad:
|
---|
76 | errno = EMSGSIZE;
|
---|
77 | return -1;
|
---|
78 | }
|
---|
79 |
|
---|
80 | int 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;
|
---|
99 | bad:
|
---|
100 | errno = EMSGSIZE;
|
---|
101 | return -1;
|
---|
102 | }
|
---|
103 |
|
---|
104 | int 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;
|
---|
155 | bad:
|
---|
156 | errno = ENODEV;
|
---|
157 | return -1;
|
---|
158 | size:
|
---|
159 | errno = EMSGSIZE;
|
---|
160 | return -1;
|
---|
161 | }
|
---|
162 |
|
---|
163 | int 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 |
|
---|