1 /* Shared library add-on to iptables to add related packet matching support. */
2 #include <stdio.h>
3 #include <netdb.h>
4 #include <string.h>
5 #include <stdlib.h>
6 #include <getopt.h>
7
8 #include <iptables.h>
9 #include <linux/netfilter_ipv4/ipt_helper.h>
10
11 /* Function which prints out usage message. */
12 static void
help(void)13 help(void)
14 {
15 printf(
16 "helper match v%s options:\n"
17 "[!] --helper string Match helper identified by string\n"
18 "\n",
19 IPTABLES_VERSION);
20 }
21
22 static struct option opts[] = {
23 { "helper", 1, 0, '1' },
24 {0}
25 };
26
27 /* Function which parses command options; returns true if it
28 ate an option */
29 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)30 parse(int c, char **argv, int invert, unsigned int *flags,
31 const struct ipt_entry *entry,
32 unsigned int *nfcache,
33 struct ipt_entry_match **match)
34 {
35 struct ipt_helper_info *info = (struct ipt_helper_info *)(*match)->data;
36
37 switch (c) {
38 case '1':
39 if (*flags)
40 exit_error(PARAMETER_PROBLEM,
41 "helper match: Only use --helper ONCE!");
42 check_inverse(optarg, &invert, &invert, 0);
43 strncpy(info->name, optarg, 29);
44 info->name[29] = '\0';
45 if (invert)
46 info->invert = 1;
47 *flags = 1;
48 break;
49
50 default:
51 return 0;
52 }
53 return 1;
54 }
55
56 /* Final check; must have specified --helper. */
57 static void
final_check(unsigned int flags)58 final_check(unsigned int flags)
59 {
60 if (!flags)
61 exit_error(PARAMETER_PROBLEM,
62 "helper match: You must specify `--helper'");
63 }
64
65 /* Prints out the info. */
66 static void
print(const struct ipt_ip * ip,const struct ipt_entry_match * match,int numeric)67 print(const struct ipt_ip *ip,
68 const struct ipt_entry_match *match,
69 int numeric)
70 {
71 struct ipt_helper_info *info = (struct ipt_helper_info *)match->data;
72
73 printf("helper match %s\"%s\" ", info->invert ? "! " : "", info->name);
74 }
75
76 /* Saves the union ipt_info in parsable form to stdout. */
77 static void
save(const struct ipt_ip * ip,const struct ipt_entry_match * match)78 save(const struct ipt_ip *ip, const struct ipt_entry_match *match)
79 {
80 struct ipt_helper_info *info = (struct ipt_helper_info *)match->data;
81
82 printf("%s--helper \"%s\" ",info->invert ? "! " : "", info->name);
83 }
84
85 static struct iptables_match helper = {
86 .next = NULL,
87 .name = "helper",
88 .version = IPTABLES_VERSION,
89 .size = IPT_ALIGN(sizeof(struct ipt_helper_info)),
90 .help = &help,
91 .parse = &parse,
92 .final_check = &final_check,
93 .print = &print,
94 .save = &save,
95 .extra_opts = opts
96 };
97
ipt_helper_init(void)98 void ipt_helper_init(void)
99 {
100 register_match(&helper);
101 }
102