range.c

/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
 * (C) 2016 by Pablo Neira Ayuso <pablo@netfilter.org>
 */

#include "internal.h"

#include <stdio.h>
#include <stdint.h>
#include <string.h>
#include <arpa/inet.h>
#include <errno.h>

#include <libmnl/libmnl.h>
#include <linux/netfilter/nf_tables.h>
#include <libnftnl/expr.h>
#include <libnftnl/rule.h>

struct nftnl_expr_range {
        union nftnl_data_reg    data_from;
        union nftnl_data_reg    data_to;
        enum nft_registers      sreg;
        enum nft_range_ops      op;
};

static int
nftnl_expr_range_set(struct nftnl_expr *e, uint16_t type,
                     const void *data, uint32_t data_len, uint32_t byteorder)
{
        struct nftnl_expr_range *range = nftnl_expr_data(e);

        switch(type) {
        case NFTNL_EXPR_RANGE_SREG:
                memcpy(&range->sreg, data, data_len);
                break;
        case NFTNL_EXPR_RANGE_OP:
                memcpy(&range->op, data, data_len);
                break;
        case NFTNL_EXPR_RANGE_FROM_DATA:
                return nftnl_data_cpy(&range->data_from, data,
                                      data_len, byteorder, NULL);
        case NFTNL_EXPR_RANGE_TO_DATA:
                return nftnl_data_cpy(&range->data_to, data,
                                      data_len, byteorder, NULL);
        }
        return 0;
}

static const void *nftnl_expr_range_get(const struct nftnl_expr *e,
                                        uint16_t type, uint32_t *data_len)
{
        struct nftnl_expr_range *range = nftnl_expr_data(e);

        switch(type) {
        case NFTNL_EXPR_RANGE_SREG:
                *data_len = sizeof(range->sreg);
                return &range->sreg;
        case NFTNL_EXPR_RANGE_OP:
                *data_len = sizeof(range->op);
                return &range->op;
        case NFTNL_EXPR_RANGE_FROM_DATA:
                *data_len = range->data_from.len;
                return &range->data_from.val;
        case NFTNL_EXPR_RANGE_TO_DATA:
                *data_len = range->data_to.len;
                return &range->data_to.val;
        }
        return NULL;
}

static int nftnl_expr_range_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_RANGE_MAX) < 0)
                return MNL_CB_OK;

        switch(type) {
        case NFTA_RANGE_SREG:
        case NFTA_RANGE_OP:
                if (mnl_attr_validate(attr, MNL_TYPE_U32) < 0)
                        abi_breakage();
                break;
        case NFTA_RANGE_FROM_DATA:
        case NFTA_RANGE_TO_DATA:
                if (mnl_attr_validate(attr, MNL_TYPE_BINARY) < 0)
                        abi_breakage();
                break;
        }

        tb[type] = attr;
        return MNL_CB_OK;
}

static void
nftnl_expr_range_build(struct nlmsghdr *nlh, const struct nftnl_expr *e)
{
        struct nftnl_expr_range *range = nftnl_expr_data(e);

        if (e->flags & (1 << NFTNL_EXPR_RANGE_SREG))
                mnl_attr_put_u32(nlh, NFTA_RANGE_SREG, htonl(range->sreg));
        if (e->flags & (1 << NFTNL_EXPR_RANGE_OP))
                mnl_attr_put_u32(nlh, NFTA_RANGE_OP, htonl(range->op));
        if (e->flags & (1 << NFTNL_EXPR_RANGE_FROM_DATA)) {
                struct nlattr *nest;

                nest = mnl_attr_nest_start(nlh, NFTA_RANGE_FROM_DATA);
                mnl_attr_put(nlh, NFTA_DATA_VALUE, range->data_from.len,
                             range->data_from.val);
                mnl_attr_nest_end(nlh, nest);
        }
        if (e->flags & (1 << NFTNL_EXPR_RANGE_TO_DATA)) {
                struct nlattr *nest;

                nest = mnl_attr_nest_start(nlh, NFTA_RANGE_TO_DATA);
                mnl_attr_put(nlh, NFTA_DATA_VALUE, range->data_to.len,
                             range->data_to.val);
                mnl_attr_nest_end(nlh, nest);
        }
}

static int
nftnl_expr_range_parse(struct nftnl_expr *e, struct nlattr *attr)
{
        struct nftnl_expr_range *range = nftnl_expr_data(e);
        struct nlattr *tb[NFTA_RANGE_MAX+1] = {};
        int ret = 0;

        if (mnl_attr_parse_nested(attr, nftnl_expr_range_cb, tb) < 0)
                return -1;

        if (tb[NFTA_RANGE_SREG]) {
                range->sreg = ntohl(mnl_attr_get_u32(tb[NFTA_RANGE_SREG]));
                e->flags |= (1 << NFTA_RANGE_SREG);
        }
        if (tb[NFTA_RANGE_OP]) {
                range->op = ntohl(mnl_attr_get_u32(tb[NFTA_RANGE_OP]));
                e->flags |= (1 << NFTA_RANGE_OP);
        }
        if (tb[NFTA_RANGE_FROM_DATA]) {
                ret = nftnl_parse_data(&range->data_from,
                                       tb[NFTA_RANGE_FROM_DATA], NULL);
                e->flags |= (1 << NFTA_RANGE_FROM_DATA);
        }
        if (tb[NFTA_RANGE_TO_DATA]) {
                ret = nftnl_parse_data(&range->data_to,
                                       tb[NFTA_RANGE_TO_DATA], NULL);
                e->flags |= (1 << NFTA_RANGE_TO_DATA);
        }

        return ret;
}

static const char *expr_range_str[] = {
        [NFT_RANGE_EQ]  = "eq",
        [NFT_RANGE_NEQ] = "neq",
};

static const char *range2str(uint32_t op)
{
        if (op > NFT_RANGE_NEQ)
                return "unknown";

        return expr_range_str[op];
}

static int nftnl_expr_range_snprintf(char *buf, size_t remain,
                                     uint32_t flags, const struct nftnl_expr *e)
{
        struct nftnl_expr_range *range = nftnl_expr_data(e);
        int offset = 0, ret;

        ret = snprintf(buf, remain, "%s reg %u ",
                       range2str(range->op), range->sreg);
        SNPRINTF_BUFFER_SIZE(ret, remain, offset);

        ret = nftnl_data_reg_snprintf(buf + offset, remain, &range->data_from,
                                      0, DATA_VALUE);
        SNPRINTF_BUFFER_SIZE(ret, remain, offset);

        ret = snprintf(buf + offset, remain, " ");
        SNPRINTF_BUFFER_SIZE(ret, remain, offset);

        ret = nftnl_data_reg_snprintf(buf + offset, remain, &range->data_to,
                                      0, DATA_VALUE);
        SNPRINTF_BUFFER_SIZE(ret, remain, offset);

        ret = snprintf(buf + offset, remain, " ");
        SNPRINTF_BUFFER_SIZE(ret, remain, offset);

        return offset;
}

static struct attr_policy range_attr_policy[__NFTNL_EXPR_RANGE_MAX] = {
        [NFTNL_EXPR_RANGE_SREG]      = { .maxlen = sizeof(uint32_t) },
        [NFTNL_EXPR_RANGE_OP]        = { .maxlen = sizeof(uint32_t) },
        [NFTNL_EXPR_RANGE_FROM_DATA] = { .maxlen = NFT_DATA_VALUE_MAXLEN },
        [NFTNL_EXPR_RANGE_TO_DATA]   = { .maxlen = NFT_DATA_VALUE_MAXLEN },
};

struct expr_ops expr_ops_range = {
        .name           = "range",
        .alloc_len      = sizeof(struct nftnl_expr_range),
        .nftnl_max_attr = __NFTNL_EXPR_RANGE_MAX - 1,
        .attr_policy    = range_attr_policy,
        .set            = nftnl_expr_range_set,
        .get            = nftnl_expr_range_get,
        .parse          = nftnl_expr_range_parse,
        .build          = nftnl_expr_range_build,
        .output         = nftnl_expr_range_snprintf,
};