libnftnl 1.2.6
numgen.c
1/*
2 * (C) 2016 by Laura Garcia <nevola@gmail.com>
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published
6 * by the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
8 *
9 */
10
11#include <stdio.h>
12#include <stdint.h>
13#include <string.h>
14#include <arpa/inet.h>
15#include <errno.h>
16#include <linux/netfilter/nf_tables.h>
17
18#include "internal.h"
19#include <libmnl/libmnl.h>
20#include <libnftnl/expr.h>
21#include <libnftnl/rule.h>
22
24 enum nft_registers dreg;
25 unsigned int modulus;
26 enum nft_ng_types type;
27 unsigned int offset;
28};
29
30static int
31nftnl_expr_ng_set(struct nftnl_expr *e, uint16_t type,
32 const void *data, uint32_t data_len)
33{
34 struct nftnl_expr_ng *ng = nftnl_expr_data(e);
35
36 switch (type) {
37 case NFTNL_EXPR_NG_DREG:
38 memcpy(&ng->dreg, data, sizeof(ng->dreg));
39 break;
40 case NFTNL_EXPR_NG_MODULUS:
41 memcpy(&ng->modulus, data, sizeof(ng->modulus));
42 break;
43 case NFTNL_EXPR_NG_TYPE:
44 memcpy(&ng->type, data, sizeof(ng->type));
45 break;
46 case NFTNL_EXPR_NG_OFFSET:
47 memcpy(&ng->offset, data, sizeof(ng->offset));
48 break;
49 default:
50 return -1;
51 }
52 return 0;
53}
54
55static const void *
56nftnl_expr_ng_get(const struct nftnl_expr *e, uint16_t type,
57 uint32_t *data_len)
58{
59 struct nftnl_expr_ng *ng = nftnl_expr_data(e);
60
61 switch (type) {
62 case NFTNL_EXPR_NG_DREG:
63 *data_len = sizeof(ng->dreg);
64 return &ng->dreg;
65 case NFTNL_EXPR_NG_MODULUS:
66 *data_len = sizeof(ng->modulus);
67 return &ng->modulus;
68 case NFTNL_EXPR_NG_TYPE:
69 *data_len = sizeof(ng->type);
70 return &ng->type;
71 case NFTNL_EXPR_NG_OFFSET:
72 *data_len = sizeof(ng->offset);
73 return &ng->offset;
74 }
75 return NULL;
76}
77
78static int nftnl_expr_ng_cb(const struct nlattr *attr, void *data)
79{
80 const struct nlattr **tb = data;
81 int type = mnl_attr_get_type(attr);
82
83 if (mnl_attr_type_valid(attr, NFTA_NG_MAX) < 0)
84 return MNL_CB_OK;
85
86 switch (type) {
87 case NFTA_NG_DREG:
88 case NFTA_NG_MODULUS:
89 case NFTA_NG_TYPE:
90 case NFTA_NG_OFFSET:
91 if (mnl_attr_validate(attr, MNL_TYPE_U32) < 0)
92 abi_breakage();
93 break;
94 }
95
96 tb[type] = attr;
97 return MNL_CB_OK;
98}
99
100static void
101nftnl_expr_ng_build(struct nlmsghdr *nlh, const struct nftnl_expr *e)
102{
103 struct nftnl_expr_ng *ng = nftnl_expr_data(e);
104
105 if (e->flags & (1 << NFTNL_EXPR_NG_DREG))
106 mnl_attr_put_u32(nlh, NFTA_NG_DREG, htonl(ng->dreg));
107 if (e->flags & (1 << NFTNL_EXPR_NG_MODULUS))
108 mnl_attr_put_u32(nlh, NFTA_NG_MODULUS, htonl(ng->modulus));
109 if (e->flags & (1 << NFTNL_EXPR_NG_TYPE))
110 mnl_attr_put_u32(nlh, NFTA_NG_TYPE, htonl(ng->type));
111 if (e->flags & (1 << NFTNL_EXPR_NG_OFFSET))
112 mnl_attr_put_u32(nlh, NFTA_NG_OFFSET, htonl(ng->offset));
113}
114
115static int
116nftnl_expr_ng_parse(struct nftnl_expr *e, struct nlattr *attr)
117{
118 struct nftnl_expr_ng *ng = nftnl_expr_data(e);
119 struct nlattr *tb[NFTA_NG_MAX+1] = {};
120 int ret = 0;
121
122 if (mnl_attr_parse_nested(attr, nftnl_expr_ng_cb, tb) < 0)
123 return -1;
124
125 if (tb[NFTA_NG_DREG]) {
126 ng->dreg = ntohl(mnl_attr_get_u32(tb[NFTA_NG_DREG]));
127 e->flags |= (1 << NFTNL_EXPR_NG_DREG);
128 }
129 if (tb[NFTA_NG_MODULUS]) {
130 ng->modulus = ntohl(mnl_attr_get_u32(tb[NFTA_NG_MODULUS]));
131 e->flags |= (1 << NFTNL_EXPR_NG_MODULUS);
132 }
133 if (tb[NFTA_NG_TYPE]) {
134 ng->type = ntohl(mnl_attr_get_u32(tb[NFTA_NG_TYPE]));
135 e->flags |= (1 << NFTNL_EXPR_NG_TYPE);
136 }
137 if (tb[NFTA_NG_OFFSET]) {
138 ng->offset = ntohl(mnl_attr_get_u32(tb[NFTA_NG_OFFSET]));
139 e->flags |= (1 << NFTNL_EXPR_NG_OFFSET);
140 }
141
142 return ret;
143}
144
145static int
146nftnl_expr_ng_snprintf(char *buf, size_t remain,
147 uint32_t flags, const struct nftnl_expr *e)
148{
149 struct nftnl_expr_ng *ng = nftnl_expr_data(e);
150 int offset = 0, ret;
151
152 switch (ng->type) {
153 case NFT_NG_INCREMENTAL:
154 ret = snprintf(buf, remain, "reg %u = inc mod %u ",
155 ng->dreg, ng->modulus);
156 SNPRINTF_BUFFER_SIZE(ret, remain, offset);
157 break;
158 case NFT_NG_RANDOM:
159 ret = snprintf(buf, remain, "reg %u = random mod %u ",
160 ng->dreg, ng->modulus);
161 SNPRINTF_BUFFER_SIZE(ret, remain, offset);
162 break;
163 default:
164 return 0;
165 }
166
167 if (ng->offset) {
168 ret = snprintf(buf + offset, remain, "offset %u ", ng->offset);
169 SNPRINTF_BUFFER_SIZE(ret, remain, offset);
170 }
171
172 return offset;
173}
174
175struct expr_ops expr_ops_ng = {
176 .name = "numgen",
177 .alloc_len = sizeof(struct nftnl_expr_ng),
178 .max_attr = NFTA_NG_MAX,
179 .set = nftnl_expr_ng_set,
180 .get = nftnl_expr_ng_get,
181 .parse = nftnl_expr_ng_parse,
182 .build = nftnl_expr_ng_build,
183 .output = nftnl_expr_ng_snprintf,
184};