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
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
|
/* Shared library add-on to iptables to add u32 matching,
* generalized matching on values found at packet offsets
*
* Detailed doc is in the kernel module source
* net/ipv4/netfilter/ipt_u32.c
*
* (C) 2002 by Don Cohen <don-netf@isis.cs3-inc.com>
* Released under the terms of GNU GPL v2
*/
#include <stdio.h>
#include <netdb.h>
#include <string.h>
#include <stdlib.h>
#include <getopt.h>
#include <iptables.h>
#include <linux/netfilter_ipv4/ipt_u32.h>
#include <errno.h>
#include <ctype.h>
/* Function which prints out usage message. */
static void
help(void)
{
printf( "u32 v%s options:\n"
" --u32 tests\n"
" tests := location = value | tests && location = value\n"
" value := range | value , range\n"
" range := number | number : number\n"
" location := number | location operator number\n"
" operator := & | << | >> | @\n"
,IPTABLES_VERSION);
}
/* defined in /usr/include/getopt.h maybe in man getopt */
static struct option opts[] = {
{ "u32", 1, 0, '1' },
{ 0 }
};
/* shared printing code */
static void print_u32(struct ipt_u32 *data)
{
unsigned int testind;
for (testind=0; testind < data->ntests; testind++) {
if (testind) printf("&&");
{
unsigned int i;
printf("0x%x", data->tests[testind].location[0].number);
for (i = 1; i < data->tests[testind].nnums; i++) {
switch (data->tests[testind].location[i].nextop) {
case IPT_U32_AND: printf("&"); break;
case IPT_U32_LEFTSH: printf("<<"); break;
case IPT_U32_RIGHTSH: printf(">>"); break;
case IPT_U32_AT: printf("@"); break;
}
printf("0x%x", data->tests[testind].location[i].number);
}
printf("=");
for (i = 0; i < data->tests[testind].nvalues; i++) {
if (i) printf(",");
if (data->tests[testind].value[i].min
== data->tests[testind].value[i].max)
printf("0x%x", data->tests[testind].value[i].min);
else printf("0x%x:0x%x", data->tests[testind].value[i].min,
data->tests[testind].value[i].max);
}
}
}
printf(" ");
}
/* string_to_number is not quite what we need here ... */
u_int32_t parse_number(char **s, int pos)
{
u_int32_t number;
char *end;
errno = 0;
number = strtoul(*s, &end, 0);
if (end == *s)
exit_error(PARAMETER_PROBLEM,
"u32: at char %d expected number", pos);
if (errno)
exit_error(PARAMETER_PROBLEM,
"u32: at char %d error reading number", pos);
*s = end;
return number;
}
/* Function which parses command options; returns true if it ate an option */
static int
parse(int c, char **argv, int invert, unsigned int *flags,
const struct ipt_entry *entry,
unsigned int *nfcache,
struct ipt_entry_match **match)
{
struct ipt_u32 *data = (struct ipt_u32 *)(*match)->data;
char *arg = argv[optind-1]; /* the argument string */
char *start = arg;
int state=0, testind=0, locind=0, valind=0;
if (c != '1') return 0;
/* states: 0 = looking for numbers and operations, 1 = looking for ranges */
while (1) { /* read next operand/number or range */
while (isspace(*arg))
arg++; /* skip white space */
if (! *arg) { /* end of argument found */
if (state == 0)
exit_error(PARAMETER_PROBLEM,
"u32: input ended in location spec");
if (valind == 0)
exit_error(PARAMETER_PROBLEM,
"u32: test ended with no value spec");
data->tests[testind].nnums = locind;
data->tests[testind].nvalues = valind;
testind++;
data->ntests=testind;
if (testind > U32MAXSIZE)
exit_error(PARAMETER_PROBLEM,
"u32: at char %d too many &&'s",
arg-start);
/* debugging
print_u32(data);printf("\n");
exit_error(PARAMETER_PROBLEM, "debugging output done"); */
return 1;
}
if (state == 0) {
/* reading location: read a number if nothing read yet,
otherwise either op number or = to end location spec */
if (*arg == '=') {
if (locind == 0)
exit_error(PARAMETER_PROBLEM,
"u32: at char %d location spec missing", arg-start);
else {
arg++;
state=1;
}
}
else {
if (locind) { /* need op before number */
if (*arg == '&') {
data->tests[testind].location[locind].nextop = IPT_U32_AND;
}
else if (*arg == '<') {
arg++;
if (*arg != '<')
exit_error(PARAMETER_PROBLEM,
"u32: at char %d a second < expected", arg-start);
data->tests[testind].location[locind].nextop = IPT_U32_LEFTSH;
}
else if (*arg == '>') {
arg++;
if (*arg != '>')
exit_error(PARAMETER_PROBLEM,
"u32: at char %d a second > expected", arg-start);
data->tests[testind].location[locind].nextop = IPT_U32_RIGHTSH;
}
else if (*arg == '@') {
data->tests[testind].location[locind].nextop = IPT_U32_AT;
}
else exit_error(PARAMETER_PROBLEM,
"u32: at char %d operator expected", arg-start);
arg++;
}
/* now a number; string_to_number skips white space? */
data->tests[testind].location[locind].number =
parse_number(&arg, arg-start);
locind++;
if (locind > U32MAXSIZE)
exit_error(PARAMETER_PROBLEM,
"u32: at char %d too many operators", arg-start);
}
}
else {
/* state 1 - reading values: read a range if nothing read yet,
otherwise either ,range or && to end test spec */
if (*arg == '&') {
arg++;
if (*arg != '&')
exit_error(PARAMETER_PROBLEM,
"u32: at char %d a second & expected", arg-start);
if (valind == 0)
exit_error(PARAMETER_PROBLEM,
"u32: at char %d value spec missing", arg-start);
else {
data->tests[testind].nnums = locind;
data->tests[testind].nvalues = valind;
testind++;
if (testind > U32MAXSIZE)
exit_error(PARAMETER_PROBLEM,
"u32: at char %d too many &&'s", arg-start);
arg++; state=0; locind=0; valind=0;
}
}
else { /* read value range */
if (valind) { /* need , before number */
if (*arg != ',')
exit_error(PARAMETER_PROBLEM,
"u32: at char %d expected , or &&", arg-start);
arg++;
}
data->tests[testind].value[valind].min = parse_number(&arg, arg-start);
while (isspace(*arg))
arg++; /* another place white space could be */
if (*arg==':') {
arg++;
data->tests[testind].value[valind].max
= parse_number(&arg, arg-start);
}
else data->tests[testind].value[valind].max
= data->tests[testind].value[valind].min;
valind++;
if (valind > U32MAXSIZE)
exit_error(PARAMETER_PROBLEM,
"u32: at char %d too many ,'s", arg-start);
}
}
}
}
/* Final check; must specify something. */
static void
final_check(unsigned int flags)
{
}
/* Prints out the matchinfo. */
static void
print(const struct ipt_ip *ip,
const struct ipt_entry_match *match,
int numeric)
{
printf("u32 ");
print_u32((struct ipt_u32 *)match->data);
}
/* Saves the union ipt_matchinfo in parsable form to stdout. */
static void save(const struct ipt_ip *ip, const struct ipt_entry_match *match)
{
printf("--u32 ");
print_u32((struct ipt_u32 *)match->data);
}
struct iptables_match u32 = {
.next = NULL,
.name = "u32",
.version = IPTABLES_VERSION,
.size = IPT_ALIGN(sizeof(struct ipt_u32)),
.userspacesize = IPT_ALIGN(sizeof(struct ipt_u32)),
.help = &help,
.parse = &parse,
.final_check = &final_check,
.print = &print,
.save = &save,
.extra_opts = opts
};
void
_init(void)
{
register_match(&u32);
}
|
