1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
|
From 2f267b57ef0e145e397be571a000a11dc8188af2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Timo=20Ter=C3=A4s?= <timo.teras@iki.fi>
Date: Mon, 14 Oct 2013 10:01:01 +0300
Subject: [PATCH] add basic dns record parsing functions
---
include/arpa/nameser.h | 24 ++++++-
src/network/ns_parse.c | 172 +++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 195 insertions(+), 1 deletion(-)
create mode 100644 src/network/ns_parse.c
diff --git a/include/arpa/nameser.h b/include/arpa/nameser.h
index b9ee665..9c5f990 100644
--- a/include/arpa/nameser.h
+++ b/include/arpa/nameser.h
@@ -1,6 +1,11 @@
#ifndef _ARPA_NAMESER_H
#define _ARPA_NAMESER_H
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <sys/types.h>
#include <stdint.h>
#define __NAMESER 19991006
@@ -48,6 +53,8 @@ extern const struct _ns_flagdata _ns_flagdata[];
#define ns_msg_end(handle) ((handle)._eom + 0)
#define ns_msg_size(handle) ((handle)._eom - (handle)._msg)
#define ns_msg_count(handle, section) ((handle)._counts[section] + 0)
+#define ns_msg_getflag(handle, flag) \
+ (((handle)._flags & _ns_flagdata[flag].mask) >> _ns_flagdata[flag].shift)
typedef struct __ns_rr {
char name[NS_MAXDNAME];
@@ -332,7 +339,18 @@ typedef enum __ns_cert_types {
(cp) += NS_INT32SZ; \
} while (0)
-
+#if defined(_GNU_SOURCE) || defined(_BSD_SOURCE)
+u_int ns_get16(const unsigned char *cp);
+u_long ns_get32(const unsigned char *cp);
+void ns_put16(u_int s, unsigned char *cp);
+void ns_put32(u_long l, unsigned char *cp);
+
+int ns_initparse(const u_char *msg, int msglen, ns_msg *handle);
+int ns_parserr(ns_msg *handle, ns_sect section, int rrnum, ns_rr *rr);
+int ns_skiprr(const u_char *msg, const u_char *eom, ns_sect section, int count);
+int ns_name_uncompress(const u_char *msg, const u_char *eom,
+ const u_char *comp_dn, char *exp_dn, size_t length);
+#endif
#define __BIND 19950621
@@ -464,4 +482,8 @@ typedef struct {
#define PUTSHORT NS_PUT16
#define PUTLONG NS_PUT32
+#ifdef __cplusplus
+}
+#endif
+
#endif
diff --git a/src/network/ns_parse.c b/src/network/ns_parse.c
new file mode 100644
index 0000000..7e40237
--- /dev/null
+++ b/src/network/ns_parse.c
@@ -0,0 +1,172 @@
+#define _BSD_SOURCE
+#include <errno.h>
+#include <stddef.h>
+#include <resolv.h>
+#include <arpa/nameser.h>
+
+const struct _ns_flagdata _ns_flagdata[16] = {
+ { 0x8000, 15 },
+ { 0x7800, 11 },
+ { 0x0400, 10 },
+ { 0x0200, 9 },
+ { 0x0100, 8 },
+ { 0x0080, 7 },
+ { 0x0040, 6 },
+ { 0x0020, 5 },
+ { 0x0010, 4 },
+ { 0x000f, 0 },
+ { 0x0000, 0 },
+ { 0x0000, 0 },
+ { 0x0000, 0 },
+ { 0x0000, 0 },
+ { 0x0000, 0 },
+ { 0x0000, 0 },
+};
+
+u_int ns_get16(const unsigned char *cp)
+{
+ u_short s;
+ NS_GET16(s, cp);
+ return s;
+}
+
+u_long ns_get32(const unsigned char *cp)
+{
+ u_long l;
+ NS_GET32(l, cp);
+ return l;
+}
+
+void ns_put16(u_int s, unsigned char *cp)
+{
+ NS_PUT16(s, cp);
+}
+
+void ns_put32(u_long l, unsigned char *cp)
+{
+ NS_PUT32(l, cp);
+}
+
+int ns_initparse(const unsigned char *msg, int msglen, ns_msg *handle)
+{
+ int i, r;
+
+ handle->_msg = msg;
+ handle->_eom = msg + msglen;
+ if (msglen < (2 + ns_s_max) * NS_INT16SZ) goto bad;
+ NS_GET16(handle->_id, msg);
+ NS_GET16(handle->_flags, msg);
+ for (i = 0; i < ns_s_max; i++) NS_GET16(handle->_counts[i], msg);
+ for (i = 0; i < ns_s_max; i++) {
+ if (handle->_counts[i]) {
+ handle->_sections[i] = msg;
+ r = ns_skiprr(msg, handle->_eom, i, handle->_counts[i]);
+ if (r < 0) return -1;
+ msg += r;
+ } else {
+ handle->_sections[i] = NULL;
+ }
+ }
+ if (msg != handle->_eom) goto bad;
+ handle->_sect = ns_s_max;
+ handle->_rrnum = -1;
+ handle->_msg_ptr = NULL;
+ return 0;
+bad:
+ errno = EMSGSIZE;
+ return -1;
+}
+
+int ns_skiprr(const u_char *ptr, const u_char *eom, ns_sect section, int count)
+{
+ const u_char *p = ptr;
+ int r;
+
+ while (count--) {
+ r = dn_skipname(p, eom);
+ if (r < 0) goto bad;
+ p += r + 2 * NS_INT16SZ;
+ if (section != ns_s_qd) {
+ if (p + NS_INT32SZ + NS_INT16SZ > eom) goto bad;
+ p += NS_INT32SZ;
+ NS_GET16(r, p);
+ p += r;
+ }
+ }
+ if (p > eom) goto bad;
+ return ptr - p;
+bad:
+ errno = EMSGSIZE;
+ return -1;
+}
+
+int ns_parserr(ns_msg *handle, ns_sect section, int rrnum, ns_rr *rr)
+{
+ int r;
+
+ if (section < 0 || section >= ns_s_max) goto bad;
+ if (section != handle->_sect) {
+ handle->_sect = section;
+ handle->_rrnum = 0;
+ handle->_msg_ptr = handle->_sections[section];
+ }
+ if (rrnum == -1) rrnum = handle->_rrnum;
+ if (rrnum < 0 || rrnum >= handle->_counts[section]) goto bad;
+ if (rrnum < handle->_rrnum) {
+ handle->_rrnum = 0;
+ handle->_msg_ptr = handle->_sections[section];
+ }
+ if (rrnum > handle->_rrnum) {
+ r = ns_skiprr(handle->_msg_ptr, handle->_eom, section, rrnum - handle->_rrnum);
+ if (r < 0) return -1;
+ handle->_msg_ptr += r;
+ handle->_rrnum = rrnum;
+ }
+ r = dn_expand(handle->_msg, handle->_eom, handle->_msg_ptr, rr->name, NS_MAXDNAME);
+ if (r < 0) return -1;
+ handle->_msg_ptr += r;
+ if (handle->_msg_ptr + 2 * NS_INT16SZ > handle->_eom) goto size;
+ NS_GET16(rr->type, handle->_msg_ptr);
+ NS_GET16(rr->rr_class, handle->_msg_ptr);
+ if (section != ns_s_qd) {
+ if (handle->_msg_ptr + NS_INT32SZ + NS_INT16SZ > handle->_eom) goto size;
+ NS_GET32(rr->ttl, handle->_msg_ptr);
+ NS_GET16(rr->rdlength, handle->_msg_ptr);
+ if (handle->_msg_ptr + rr->rdlength > handle->_eom) goto size;
+ rr->rdata = handle->_msg_ptr;
+ handle->_msg_ptr += rr->rdlength;
+ } else {
+ rr->ttl = 0;
+ rr->rdlength = 0;
+ rr->rdata = NULL;
+ }
+ handle->_rrnum++;
+ if (handle->_rrnum > handle->_counts[section]) {
+ handle->_sect = section + 1;
+ if (handle->_sect == ns_s_max) {
+ handle->_rrnum = -1;
+ handle->_msg_ptr = NULL;
+ } else {
+ handle->_rrnum = 0;
+ }
+ }
+ return 0;
+bad:
+ errno = ENODEV;
+ return -1;
+size:
+ errno = EMSGSIZE;
+ return -1;
+}
+
+int __dn_expand(const unsigned char *, const unsigned char *, const unsigned char *, char *, int);
+
+int ns_name_uncompress(const u_char *msg, const u_char *eom,
+ const u_char *src, char *dst, size_t dstsiz)
+{
+ int r;
+ r = __dn_expand(msg, eom, src, dst, dstsiz);
+ if (r < 0) errno = EMSGSIZE;
+ return r;
+}
+
--
2.0.2
|
