1/* Shared library add-on to iptables to add recent 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_recent.h>
10
11/* Need these in order to not fail when compiling against an older kernel. */
12#ifndef RECENT_NAME
13#define RECENT_NAME	"ipt_recent"
14#endif /* RECENT_NAME */
15
16#ifndef RECENT_VER
17#define RECENT_VER	"unknown"
18#endif /* RECENT_VER */
19
20#ifndef IPT_RECENT_NAME_LEN
21#define IPT_RECENT_NAME_LEN	200
22#endif /* IPT_RECENT_NAME_LEN */
23
24/* Options for this module */
25static struct option opts[] = {
26	{ .name = "set",      .has_arg = 0, .flag = 0, .val = 201 },
27	{ .name = "rcheck",   .has_arg = 0, .flag = 0, .val = 202 },
28	{ .name = "update",   .has_arg = 0, .flag = 0, .val = 203 },
29	{ .name = "seconds",  .has_arg = 1, .flag = 0, .val = 204 },
30	{ .name = "hitcount", .has_arg = 1, .flag = 0, .val = 205 },
31	{ .name = "remove",   .has_arg = 0, .flag = 0, .val = 206 },
32	{ .name = "rttl",     .has_arg = 0, .flag = 0, .val = 207 },
33	{ .name = "name",     .has_arg = 1, .flag = 0, .val = 208 },
34	{ .name = "rsource",  .has_arg = 0, .flag = 0, .val = 209 },
35	{ .name = "rdest",    .has_arg = 0, .flag = 0, .val = 210 },
36	{ .name = 0,          .has_arg = 0, .flag = 0, .val = 0   }
37};
38
39/* Function which prints out usage message. */
40static void
41help(void)
42{
43	printf(
44"recent v%s options:\n"
45"[!] --set                       Add source address to list, always matches.\n"
46"[!] --rcheck                    Match if source address in list.\n"
47"[!] --update                    Match if source address in list, also update last-seen time.\n"
48"[!] --remove                    Match if source address in list, also removes that address from list.\n"
49"    --seconds seconds           For check and update commands above.\n"
50"                                Specifies that the match will only occur if source address last seen within\n"
51"                                the last 'seconds' seconds.\n"
52"    --hitcount hits             For check and update commands above.\n"
53"                                Specifies that the match will only occur if source address seen hits times.\n"
54"                                May be used in conjunction with the seconds option.\n"
55"    --rttl                      For check and update commands above.\n"
56"                                Specifies that the match will only occur if the source address and the TTL\n"
57"                                match between this packet and the one which was set.\n"
58"                                Useful if you have problems with people spoofing their source address in order\n"
59"                                to DoS you via this module.\n"
60"    --name name                 Name of the recent list to be used.  DEFAULT used if none given.\n"
61"    --rsource                   Match/Save the source address of each packet in the recent list table (default).\n"
62"    --rdest                     Match/Save the destination address of each packet in the recent list table.\n"
63RECENT_NAME " " RECENT_VER ": Stephen Frost <sfrost@snowman.net>.  http://snowman.net/projects/ipt_recent/\n"
64,
65IPTABLES_VERSION);
66
67}
68
69/* Initialize the match. */
70static void
71init(struct ipt_entry_match *match, unsigned int *nfcache)
72{
73	struct ipt_recent_info *info = (struct ipt_recent_info *)(match)->data;
74
75
76	strncpy(info->name,"DEFAULT",IPT_RECENT_NAME_LEN);
77	/* eventhough IPT_RECENT_NAME_LEN is currently defined as 200,
78	 * better be safe, than sorry */
79	info->name[IPT_RECENT_NAME_LEN-1] = '\0';
80	info->side = IPT_RECENT_SOURCE;
81}
82
83/* Function which parses command options; returns true if it
84   ate an option */
85static int
86parse(int c, char **argv, int invert, unsigned int *flags,
87      const struct ipt_entry *entry,
88      unsigned int *nfcache,
89      struct ipt_entry_match **match)
90{
91	struct ipt_recent_info *info = (struct ipt_recent_info *)(*match)->data;
92	switch (c) {
93		case 201:
94			if (*flags) exit_error(PARAMETER_PROBLEM,
95					"recent: only one of `--set', `--rcheck' "
96					"`--update' or `--remove' may be set");
97			check_inverse(optarg, &invert, &optind, 0);
98			info->check_set |= IPT_RECENT_SET;
99			if (invert) info->invert = 1;
100			*flags = 1;
101			break;
102
103		case 202:
104			if (*flags) exit_error(PARAMETER_PROBLEM,
105					"recent: only one of `--set', `--rcheck' "
106					"`--update' or `--remove' may be set");
107			check_inverse(optarg, &invert, &optind, 0);
108			info->check_set |= IPT_RECENT_CHECK;
109			if(invert) info->invert = 1;
110			*flags = 1;
111			break;
112
113		case 203:
114			if (*flags) exit_error(PARAMETER_PROBLEM,
115					"recent: only one of `--set', `--rcheck' "
116					"`--update' or `--remove' may be set");
117			check_inverse(optarg, &invert, &optind, 0);
118			info->check_set |= IPT_RECENT_UPDATE;
119			if (invert) info->invert = 1;
120			*flags = 1;
121			break;
122
123		case 206:
124			if (*flags) exit_error(PARAMETER_PROBLEM,
125					"recent: only one of `--set', `--rcheck' "
126					"`--update' or `--remove' may be set");
127			check_inverse(optarg, &invert, &optind, 0);
128			info->check_set |= IPT_RECENT_REMOVE;
129			if (invert) info->invert = 1;
130			*flags = 1;
131			break;
132
133		case 204:
134			info->seconds = atoi(optarg);
135			break;
136
137		case 205:
138			info->hit_count = atoi(optarg);
139			break;
140
141		case 207:
142			info->check_set |= IPT_RECENT_TTL;
143			break;
144
145		case 208:
146			strncpy(info->name,optarg,IPT_RECENT_NAME_LEN);
147			info->name[IPT_RECENT_NAME_LEN-1] = '\0';
148			break;
149
150		case 209:
151			info->side = IPT_RECENT_SOURCE;
152			break;
153
154		case 210:
155			info->side = IPT_RECENT_DEST;
156			break;
157
158		default:
159			return 0;
160	}
161
162	return 1;
163}
164
165/* Final check; must have specified a specific option. */
166static void
167final_check(unsigned int flags)
168{
169
170	if (!flags)
171		exit_error(PARAMETER_PROBLEM,
172			"recent: you must specify one of `--set', `--rcheck' "
173			"`--update' or `--remove'");
174}
175
176/* Prints out the matchinfo. */
177static void
178print(const struct ipt_ip *ip,
179      const struct ipt_entry_match *match,
180      int numeric)
181{
182	struct ipt_recent_info *info = (struct ipt_recent_info *)match->data;
183
184	if (info->invert)
185		fputc('!', stdout);
186
187	printf("recent: ");
188	if(info->check_set & IPT_RECENT_SET) printf("SET ");
189	if(info->check_set & IPT_RECENT_CHECK) printf("CHECK ");
190	if(info->check_set & IPT_RECENT_UPDATE) printf("UPDATE ");
191	if(info->check_set & IPT_RECENT_REMOVE) printf("REMOVE ");
192	if(info->seconds) printf("seconds: %d ",info->seconds);
193	if(info->hit_count) printf("hit_count: %d ",info->hit_count);
194	if(info->check_set & IPT_RECENT_TTL) printf("TTL-Match ");
195	if(info->name) printf("name: %s ",info->name);
196	if(info->side == IPT_RECENT_SOURCE) printf("side: source ");
197	if(info->side == IPT_RECENT_DEST) printf("side: dest");
198}
199
200/* Saves the union ipt_matchinfo in parsable form to stdout. */
201static void
202save(const struct ipt_ip *ip, const struct ipt_entry_match *match)
203{
204	struct ipt_recent_info *info = (struct ipt_recent_info *)match->data;
205
206	if (info->invert)
207		printf("! ");
208
209	if(info->check_set & IPT_RECENT_SET) printf("--set ");
210	if(info->check_set & IPT_RECENT_CHECK) printf("--rcheck ");
211	if(info->check_set & IPT_RECENT_UPDATE) printf("--update ");
212	if(info->check_set & IPT_RECENT_REMOVE) printf("--remove ");
213	if(info->seconds) printf("--seconds %d ",info->seconds);
214	if(info->hit_count) printf("--hitcount %d ",info->hit_count);
215	if(info->check_set & IPT_RECENT_TTL) printf("--rttl ");
216	if(info->name) printf("--name %s ",info->name);
217	if(info->side == IPT_RECENT_SOURCE) printf("--rsource ");
218	if(info->side == IPT_RECENT_DEST) printf("--rdest ");
219}
220
221/* Structure for iptables to use to communicate with module */
222static struct iptables_match recent = {
223    .next          = NULL,
224    .name          = "recent",
225    .version       = IPTABLES_VERSION,
226    .size          = IPT_ALIGN(sizeof(struct ipt_recent_info)),
227    .userspacesize = IPT_ALIGN(sizeof(struct ipt_recent_info)),
228    .help          = &help,
229    .init          = &init,
230    .parse         = &parse,
231    .final_check   = &final_check,
232    .print         = &print,
233    .save          = &save,
234    .extra_opts    = opts
235};
236
237void _init(void)
238{
239	register_match(&recent);
240}
241