numgen.c
/*
* (C) 2016 by Laura Garcia <nevola@gmail.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published
* by the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
*/
#include <stdio.h>
#include <stdint.h>
#include <string.h>
#include <arpa/inet.h>
#include <errno.h>
#include <linux/netfilter/nf_tables.h>
#include "internal.h"
#include <libmnl/libmnl.h>
#include <libnftnl/expr.h>
#include <libnftnl/rule.h>
struct nftnl_expr_ng {
enum nft_registers dreg;
unsigned int modulus;
enum nft_ng_types type;
unsigned int offset;
};
static int
nftnl_expr_ng_set(struct nftnl_expr *e, uint16_t type,
const void *data, uint32_t data_len)
{
struct nftnl_expr_ng *ng = nftnl_expr_data(e);
switch (type) {
case NFTNL_EXPR_NG_DREG:
memcpy(&ng->dreg, data, sizeof(ng->dreg));
break;
case NFTNL_EXPR_NG_MODULUS:
memcpy(&ng->modulus, data, sizeof(ng->modulus));
break;
case NFTNL_EXPR_NG_TYPE:
memcpy(&ng->type, data, sizeof(ng->type));
break;
case NFTNL_EXPR_NG_OFFSET:
memcpy(&ng->offset, data, sizeof(ng->offset));
break;
default:
return -1;
}
return 0;
}
static const void *
nftnl_expr_ng_get(const struct nftnl_expr *e, uint16_t type,
uint32_t *data_len)
{
struct nftnl_expr_ng *ng = nftnl_expr_data(e);
switch (type) {
case NFTNL_EXPR_NG_DREG:
*data_len = sizeof(ng->dreg);
return &ng->dreg;
case NFTNL_EXPR_NG_MODULUS:
*data_len = sizeof(ng->modulus);
return &ng->modulus;
case NFTNL_EXPR_NG_TYPE:
*data_len = sizeof(ng->type);
return &ng->type;
case NFTNL_EXPR_NG_OFFSET:
*data_len = sizeof(ng->offset);
return &ng->offset;
}
return NULL;
}
static int nftnl_expr_ng_cb(const struct nlattr *attr, void *data)
{
const struct nlattr **tb = data;
int type = mnl_attr_get_type(attr);
if (mnl_attr_type_valid(attr, NFTA_NG_MAX) < 0)
return MNL_CB_OK;
switch (type) {
case NFTA_NG_DREG:
case NFTA_NG_MODULUS:
case NFTA_NG_TYPE:
case NFTA_NG_OFFSET:
if (mnl_attr_validate(attr, MNL_TYPE_U32) < 0)
abi_breakage();
break;
}
tb[type] = attr;
return MNL_CB_OK;
}
static void
nftnl_expr_ng_build(struct nlmsghdr *nlh, const struct nftnl_expr *e)
{
struct nftnl_expr_ng *ng = nftnl_expr_data(e);
if (e->flags & (1 << NFTNL_EXPR_NG_DREG))
mnl_attr_put_u32(nlh, NFTA_NG_DREG, htonl(ng->dreg));
if (e->flags & (1 << NFTNL_EXPR_NG_MODULUS))
mnl_attr_put_u32(nlh, NFTA_NG_MODULUS, htonl(ng->modulus));
if (e->flags & (1 << NFTNL_EXPR_NG_TYPE))
mnl_attr_put_u32(nlh, NFTA_NG_TYPE, htonl(ng->type));
if (e->flags & (1 << NFTNL_EXPR_NG_OFFSET))
mnl_attr_put_u32(nlh, NFTA_NG_OFFSET, htonl(ng->offset));
}
static int
nftnl_expr_ng_parse(struct nftnl_expr *e, struct nlattr *attr)
{
struct nftnl_expr_ng *ng = nftnl_expr_data(e);
struct nlattr *tb[NFTA_NG_MAX+1] = {};
int ret = 0;
if (mnl_attr_parse_nested(attr, nftnl_expr_ng_cb, tb) < 0)
return -1;
if (tb[NFTA_NG_DREG]) {
ng->dreg = ntohl(mnl_attr_get_u32(tb[NFTA_NG_DREG]));
e->flags |= (1 << NFTNL_EXPR_NG_DREG);
}
if (tb[NFTA_NG_MODULUS]) {
ng->modulus = ntohl(mnl_attr_get_u32(tb[NFTA_NG_MODULUS]));
e->flags |= (1 << NFTNL_EXPR_NG_MODULUS);
}
if (tb[NFTA_NG_TYPE]) {
ng->type = ntohl(mnl_attr_get_u32(tb[NFTA_NG_TYPE]));
e->flags |= (1 << NFTNL_EXPR_NG_TYPE);
}
if (tb[NFTA_NG_OFFSET]) {
ng->offset = ntohl(mnl_attr_get_u32(tb[NFTA_NG_OFFSET]));
e->flags |= (1 << NFTNL_EXPR_NG_OFFSET);
}
return ret;
}
static int
nftnl_expr_ng_snprintf_default(char *buf, size_t size,
const struct nftnl_expr *e)
{
struct nftnl_expr_ng *ng = nftnl_expr_data(e);
int remain = size, offset = 0, ret;
switch (ng->type) {
case NFT_NG_INCREMENTAL:
ret = snprintf(buf, remain, "reg %u = inc mod %u ",
ng->dreg, ng->modulus);
SNPRINTF_BUFFER_SIZE(ret, remain, offset);
break;
case NFT_NG_RANDOM:
ret = snprintf(buf, remain, "reg %u = random mod %u ",
ng->dreg, ng->modulus);
SNPRINTF_BUFFER_SIZE(ret, remain, offset);
break;
default:
return 0;
}
if (ng->offset) {
ret = snprintf(buf + offset, remain, "offset %u ", ng->offset);
SNPRINTF_BUFFER_SIZE(ret, remain, offset);
}
return offset;
}
static int
nftnl_expr_ng_snprintf(char *buf, size_t len, uint32_t type,
uint32_t flags, const struct nftnl_expr *e)
{
switch (type) {
case NFTNL_OUTPUT_DEFAULT:
return nftnl_expr_ng_snprintf_default(buf, len, e);
case NFTNL_OUTPUT_XML:
case NFTNL_OUTPUT_JSON:
default:
break;
}
return -1;
}
struct expr_ops expr_ops_ng = {
.name = "numgen",
.alloc_len = sizeof(struct nftnl_expr_ng),
.max_attr = NFTA_NG_MAX,
.set = nftnl_expr_ng_set,
.get = nftnl_expr_ng_get,
.parse = nftnl_expr_ng_parse,
.build = nftnl_expr_ng_build,
.snprintf = nftnl_expr_ng_snprintf,
};
nftnl_expr_ng
Definition: numgen.c:23