summaryrefslogtreecommitdiffstats
path: root/iptables/xshared.c
blob: 79da507d74c0bed0c84599a373cc598540d2188a (plain)
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
#include <getopt.h>
#include <libgen.h>
#include <netdb.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <xtables.h>
#include "xshared.h"

/*
 * Print out any special helps. A user might like to be able to add a --help
 * to the commandline, and see expected results. So we call help for all
 * specified matches and targets.
 */
void print_extension_helps(const struct xtables_target *t,
    const struct xtables_rule_match *m)
{
	for (; t != NULL; t = t->next) {
		if (t->used) {
			printf("\n");
			if (t->help == NULL)
				printf("%s does not take any options\n",
				       t->name);
			else
				t->help();
		}
	}
	for (; m != NULL; m = m->next) {
		printf("\n");
		if (m->match->help == NULL)
			printf("%s does not take any options\n",
			       m->match->name);
		else
			m->match->help();
	}
}

const char *
proto_to_name(uint8_t proto, int nolookup)
{
	unsigned int i;

	if (proto && !nolookup) {
		struct protoent *pent = getprotobynumber(proto);
		if (pent)
			return pent->p_name;
	}

	for (i = 0; xtables_chain_protos[i].name != NULL; ++i)
		if (xtables_chain_protos[i].num == proto)
			return xtables_chain_protos[i].name;

	return NULL;
}

static struct xtables_match *
find_proto(const char *pname, enum xtables_tryload tryload,
	   int nolookup, struct xtables_rule_match **matches)
{
	unsigned int proto;

	if (xtables_strtoui(pname, NULL, &proto, 0, UINT8_MAX)) {
		const char *protoname = proto_to_name(proto, nolookup);

		if (protoname)
			return xtables_find_match(protoname, tryload, matches);
	} else
		return xtables_find_match(pname, tryload, matches);

	return NULL;
}

/*
 * Some explanations (after four different bugs in 3 different releases): If
 * we encounter a parameter, that has not been parsed yet, it's not an option
 * of an explicitly loaded match or a target. However, we support implicit
 * loading of the protocol match extension. '-p tcp' means 'l4 proto 6' and at
 * the same time 'load tcp protocol match on demand if we specify --dport'.
 *
 * To make this work, we need to make sure:
 * - the parameter has not been parsed by a match (m above)
 * - a protocol has been specified
 * - the protocol extension has not been loaded yet, or is loaded and unused
 *   [think of ip6tables-restore!]
 * - the protocol extension can be successively loaded
 */
static bool should_load_proto(struct iptables_command_state *cs)
{
	if (cs->protocol == NULL)
		return false;
	if (find_proto(cs->protocol, XTF_DONT_LOAD,
	    cs->options & OPT_NUMERIC, NULL) == NULL)
		return true;
	return !cs->proto_used;
}

struct xtables_match *load_proto(struct iptables_command_state *cs)
{
	if (!should_load_proto(cs))
		return NULL;
	return find_proto(cs->protocol, XTF_TRY_LOAD,
			  cs->options & OPT_NUMERIC, &cs->matches);
}

int command_default(struct iptables_command_state *cs,
		    struct xtables_globals *gl)
{
	struct xtables_rule_match *matchp;
	struct xtables_match *m;

	if (cs->target != NULL &&
	    (cs->target->parse != NULL || cs->target->x6_parse != NULL) &&
	    cs->c >= cs->target->option_offset &&
	    cs->c < cs->target->option_offset + XT_OPTION_OFFSET_SCALE) {
		xtables_option_tpcall(cs->c, cs->argv, cs->invert,
				      cs->target, &cs->fw);
		return 0;
	}

	for (matchp = cs->matches; matchp; matchp = matchp->next) {
		m = matchp->match;

		if (matchp->completed ||
		    (m->x6_parse == NULL && m->parse == NULL))
			continue;
		if (cs->c < matchp->match->option_offset ||
		    cs->c >= matchp->match->option_offset + XT_OPTION_OFFSET_SCALE)
			continue;
		xtables_option_mpcall(cs->c, cs->argv, cs->invert, m, &cs->fw);
		return 0;
	}

	/* Try loading protocol */
	m = load_proto(cs);
	if (m != NULL) {
		size_t size;

		cs->proto_used = 1;

		size = XT_ALIGN(sizeof(struct ip6t_entry_match)) + m->size;

		m->m = xtables_calloc(1, size);
		m->m->u.match_size = size;
		strcpy(m->m->u.user.name, m->name);
		m->m->u.user.revision = m->revision;
		xs_init_match(m);

		if (m->x6_options != NULL)
			gl->opts = xtables_options_xfrm(gl->orig_opts,
							gl->opts,
							m->x6_options,
							&m->option_offset);
		else
			gl->opts = xtables_merge_options(gl->orig_opts,
							 gl->opts,
							 m->extra_opts,
							 &m->option_offset);
		if (gl->opts == NULL)
			xtables_error(OTHER_PROBLEM, "can't alloc memory!");
		optind--;
		/* Indicate to rerun getopt *immediately* */
 		return 1;
	}

	if (cs->c == ':')
		xtables_error(PARAMETER_PROBLEM, "option \"%s\" "
		              "requires an argument", cs->argv[optind-1]);
	if (cs->c == '?')
		xtables_error(PARAMETER_PROBLEM, "unknown option "
			      "\"%s\"", cs->argv[optind-1]);
	xtables_error(PARAMETER_PROBLEM, "Unknown arg \"%s\"", optarg);
	return 0;
}

static mainfunc_t subcmd_get(const char *cmd, const struct subcommand *cb)
{
	for (; cb->name != NULL; ++cb)
		if (strcmp(cb->name, cmd) == 0)
			return cb->main;
	return NULL;
}

int subcmd_main(int argc, char **argv, const struct subcommand *cb)
{
	const char *cmd = basename(*argv);
	mainfunc_t f = subcmd_get(cmd, cb);

	if (f == NULL && argc > 1) {
		/*
		 * Unable to find a main method for our command name?
		 * Let's try again with the first argument!
		 */
		++argv;
		--argc;
		f = subcmd_get(*argv, cb);
	}

	/* now we should have a valid function pointer */
	if (f != NULL)
		return f(argc, argv);

	fprintf(stderr, "ERROR: No valid subcommand given.\nValid subcommands:\n");
	for (; cb->name != NULL; ++cb)
		fprintf(stderr, " * %s\n", cb->name);
	exit(EXIT_FAILURE);
}

void xs_init_target(struct xtables_target *target)
{
	if (target->udata_size != 0) {
		free(target->udata);
		target->udata = calloc(1, target->udata_size);
		if (target->udata == NULL)
			xtables_error(RESOURCE_PROBLEM, "malloc");
	}
	if (target->init != NULL)
		target->init(target->t);
}

void xs_init_match(struct xtables_match *match)
{
	if (match->udata_size != 0) {
		/*
		 * As soon as a subsequent instance of the same match
		 * is used, e.g. "-m time -m time", the first instance
		 * is no longer reachable anyway, so we can free udata.
		 * Same goes for target.
		 */
		free(match->udata);
		match->udata = calloc(1, match->udata_size);
		if (match->udata == NULL)
			xtables_error(RESOURCE_PROBLEM, "malloc");
	}
	if (match->init != NULL)
		match->init(match->m);
}