libip6t_ah.c revision bbe83862a5e1baf15f7c923352d4afdf59bc70e2 
1/* Shared library add-on to ip6tables to add AH support. */
2#include <stdio.h>
3#include <netdb.h>
4#include <string.h>
5#include <stdlib.h>
6#include <getopt.h>
7#include <errno.h>
8#include <xtables.h>
9#include <linux/netfilter_ipv6/ip6t_ah.h>
10
11static void ah_help(void)
12{
13	printf(
14"ah match options:\n"
15"[!] --ahspi spi[:spi]          match spi (range)\n"
16"[!] --ahlen length             total length of this header\n"
17" --ahres                       check the reserved filed, too\n");
18}
19
20static const struct option ah_opts[] = {
21	{ .name = "ahspi", .has_arg = 1, .val = '1' },
22	{ .name = "ahlen", .has_arg = 1, .val = '2' },
23	{ .name = "ahres", .has_arg = 0, .val = '3' },
24	{ .name = NULL }
25};
26
27static u_int32_t
28parse_ah_spi(const char *spistr, const char *typestr)
29{
30	unsigned long int spi;
31	char* ep;
32
33	spi = strtoul(spistr, &ep, 0);
34
35	if ( spistr == ep )
36		xtables_error(PARAMETER_PROBLEM,
37			   "AH no valid digits in %s `%s'", typestr, spistr);
38
39	if ( spi == ULONG_MAX  && errno == ERANGE )
40		xtables_error(PARAMETER_PROBLEM,
41			   "%s `%s' specified too big: would overflow",
42			   typestr, spistr);
43
44	if ( *spistr != '\0'  && *ep != '\0' )
45		xtables_error(PARAMETER_PROBLEM,
46			   "AH error parsing %s `%s'", typestr, spistr);
47
48	return spi;
49}
50
51static void
52parse_ah_spis(const char *spistring, u_int32_t *spis)
53{
54	char *buffer;
55	char *cp;
56
57	buffer = strdup(spistring);
58	if ((cp = strchr(buffer, ':')) == NULL)
59		spis[0] = spis[1] = parse_ah_spi(buffer, "spi");
60	else {
61		*cp = '\0';
62		cp++;
63
64		spis[0] = buffer[0] ? parse_ah_spi(buffer, "spi") : 0;
65		spis[1] = cp[0] ? parse_ah_spi(cp, "spi") : 0xFFFFFFFF;
66	}
67	free(buffer);
68}
69
70static void ah_init(struct xt_entry_match *m)
71{
72	struct ip6t_ah *ahinfo = (struct ip6t_ah *)m->data;
73
74	ahinfo->spis[1] = 0xFFFFFFFF;
75	ahinfo->hdrlen = 0;
76	ahinfo->hdrres = 0;
77}
78
79static int ah_parse(int c, char **argv, int invert, unsigned int *flags,
80                    const void *entry, struct xt_entry_match **match)
81{
82	struct ip6t_ah *ahinfo = (struct ip6t_ah *)(*match)->data;
83
84	switch (c) {
85	case '1':
86		if (*flags & IP6T_AH_SPI)
87			xtables_error(PARAMETER_PROBLEM,
88				   "Only one `--ahspi' allowed");
89		xtables_check_inverse(optarg, &invert, &optind, 0, argv);
90		parse_ah_spis(optarg, ahinfo->spis);
91		if (invert)
92			ahinfo->invflags |= IP6T_AH_INV_SPI;
93		*flags |= IP6T_AH_SPI;
94		break;
95	case '2':
96		if (*flags & IP6T_AH_LEN)
97			xtables_error(PARAMETER_PROBLEM,
98				   "Only one `--ahlen' allowed");
99		xtables_check_inverse(optarg, &invert, &optind, 0, argv);
100		ahinfo->hdrlen = parse_ah_spi(optarg, "length");
101		if (invert)
102			ahinfo->invflags |= IP6T_AH_INV_LEN;
103		*flags |= IP6T_AH_LEN;
104		break;
105	case '3':
106		if (*flags & IP6T_AH_RES)
107			xtables_error(PARAMETER_PROBLEM,
108				   "Only one `--ahres' allowed");
109		ahinfo->hdrres = 1;
110		*flags |= IP6T_AH_RES;
111		break;
112	default:
113		return 0;
114	}
115
116	return 1;
117}
118
119static void
120print_spis(const char *name, u_int32_t min, u_int32_t max,
121	    int invert)
122{
123	const char *inv = invert ? "!" : "";
124
125	if (min != 0 || max != 0xFFFFFFFF || invert) {
126		if (min == max)
127			printf("%s:%s%u ", name, inv, min);
128		else
129			printf("%ss:%s%u:%u ", name, inv, min, max);
130	}
131}
132
133static void
134print_len(const char *name, u_int32_t len, int invert)
135{
136	const char *inv = invert ? "!" : "";
137
138	if (len != 0 || invert)
139		printf("%s:%s%u ", name, inv, len);
140}
141
142static void ah_print(const void *ip, const struct xt_entry_match *match,
143                     int numeric)
144{
145	const struct ip6t_ah *ah = (struct ip6t_ah *)match->data;
146
147	printf("ah ");
148	print_spis("spi", ah->spis[0], ah->spis[1],
149		    ah->invflags & IP6T_AH_INV_SPI);
150	print_len("length", ah->hdrlen,
151		    ah->invflags & IP6T_AH_INV_LEN);
152
153	if (ah->hdrres)
154		printf("reserved ");
155
156	if (ah->invflags & ~IP6T_AH_INV_MASK)
157		printf("Unknown invflags: 0x%X ",
158		       ah->invflags & ~IP6T_AH_INV_MASK);
159}
160
161static void ah_save(const void *ip, const struct xt_entry_match *match)
162{
163	const struct ip6t_ah *ahinfo = (struct ip6t_ah *)match->data;
164
165	if (!(ahinfo->spis[0] == 0
166	    && ahinfo->spis[1] == 0xFFFFFFFF)) {
167		printf("%s--ahspi ",
168			(ahinfo->invflags & IP6T_AH_INV_SPI) ? "! " : "");
169		if (ahinfo->spis[0]
170		    != ahinfo->spis[1])
171			printf("%u:%u ",
172			       ahinfo->spis[0],
173			       ahinfo->spis[1]);
174		else
175			printf("%u ",
176			       ahinfo->spis[0]);
177	}
178
179	if (ahinfo->hdrlen != 0 || (ahinfo->invflags & IP6T_AH_INV_LEN) ) {
180		printf("%s--ahlen %u ",
181			(ahinfo->invflags & IP6T_AH_INV_LEN) ? "! " : "",
182			ahinfo->hdrlen);
183	}
184
185	if (ahinfo->hdrres != 0 )
186		printf("--ahres ");
187}
188
189static struct xtables_match ah_mt6_reg = {
190	.name          = "ah",
191	.version       = XTABLES_VERSION,
192	.family        = NFPROTO_IPV6,
193	.size          = XT_ALIGN(sizeof(struct ip6t_ah)),
194	.userspacesize = XT_ALIGN(sizeof(struct ip6t_ah)),
195	.help          = ah_help,
196	.init          = ah_init,
197	.parse         = ah_parse,
198	.print         = ah_print,
199	.save          = ah_save,
200	.extra_opts    = ah_opts,
201};
202
203void
204_init(void)
205{
206	xtables_register_match(&ah_mt6_reg);
207}
208