osf.c

#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>

#define OSF_GENRE_SIZE  32

struct nftnl_expr_osf {
        enum nft_registers      dreg;
        uint8_t                 ttl;
        uint32_t                flags;
};

static int
nftnl_expr_osf_set(struct nftnl_expr *e, uint16_t type,
                   const void *data, uint32_t data_len, uint32_t byteorder)
{
        struct nftnl_expr_osf *osf = nftnl_expr_data(e);

        switch(type) {
        case NFTNL_EXPR_OSF_DREG:
                memcpy(&osf->dreg, data, data_len);
                break;
        case NFTNL_EXPR_OSF_TTL:
                memcpy(&osf->ttl, data, data_len);
                break;
        case NFTNL_EXPR_OSF_FLAGS:
                memcpy(&osf->flags, data, data_len);
                break;
        }
        return 0;
}

static const void *
nftnl_expr_osf_get(const struct nftnl_expr *e, uint16_t type,
                   uint32_t *data_len)
{
        struct nftnl_expr_osf *osf = nftnl_expr_data(e);

        switch(type) {
        case NFTNL_EXPR_OSF_DREG:
                *data_len = sizeof(osf->dreg);
                return &osf->dreg;
        case NFTNL_EXPR_OSF_TTL:
                *data_len = sizeof(osf->ttl);
                return &osf->ttl;
        case NFTNL_EXPR_OSF_FLAGS:
                *data_len = sizeof(osf->flags);
                return &osf->flags;
        }
        return NULL;
}

static int nftnl_expr_osf_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_OSF_MAX) < 0)
                return MNL_CB_OK;

        switch(type) {
        case NFTNL_EXPR_OSF_DREG:
        case NFTNL_EXPR_OSF_FLAGS:
                if (mnl_attr_validate(attr, MNL_TYPE_U32) < 0)
                        abi_breakage();
                break;

        case NFTNL_EXPR_OSF_TTL:
                if (mnl_attr_validate(attr, MNL_TYPE_U8) < 0)
                        abi_breakage();
                break;

        }

        tb[type] = attr;
        return MNL_CB_OK;
}

static void
nftnl_expr_osf_build(struct nlmsghdr *nlh, const struct nftnl_expr *e)
{
        struct nftnl_expr_osf *osf = nftnl_expr_data(e);

        if (e->flags & (1 << NFTNL_EXPR_OSF_DREG))
                mnl_attr_put_u32(nlh, NFTA_OSF_DREG, htonl(osf->dreg));
        if (e->flags & (1 << NFTNL_EXPR_OSF_TTL))
                mnl_attr_put_u8(nlh, NFTA_OSF_TTL, osf->ttl);
        if (e->flags & (1 << NFTNL_EXPR_OSF_FLAGS))
                if (osf->flags)
                        mnl_attr_put_u32(nlh, NFTA_OSF_FLAGS, htonl(osf->flags));
}

static int
nftnl_expr_osf_parse(struct nftnl_expr *e, struct nlattr *attr)
{
        struct nftnl_expr_osf *osf = nftnl_expr_data(e);
        struct nlattr *tb[NFTA_OSF_MAX + 1] = {};

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

        if (tb[NFTA_OSF_DREG]) {
                osf->dreg = ntohl(mnl_attr_get_u32(tb[NFTA_OSF_DREG]));
                e->flags |= (1 << NFTNL_EXPR_OSF_DREG);
        }

        if (tb[NFTA_OSF_TTL]) {
                osf->ttl = mnl_attr_get_u8(tb[NFTA_OSF_TTL]);
                e->flags |= (1 << NFTNL_EXPR_OSF_TTL);
        }

        if (tb[NFTA_OSF_FLAGS]) {
                osf->flags = ntohl(mnl_attr_get_u32(tb[NFTA_OSF_FLAGS]));
                e->flags |= (1 << NFTNL_EXPR_OSF_FLAGS);
        }

        return 0;
}

static int
nftnl_expr_osf_snprintf(char *buf, size_t len,
                        uint32_t flags, const struct nftnl_expr *e)
{
        struct nftnl_expr_osf *osf = nftnl_expr_data(e);
        int ret, offset = 0;

        if (e->flags & (1 << NFTNL_EXPR_OSF_DREG)) {
                ret = snprintf(buf, len, "dreg %u ", osf->dreg);
                SNPRINTF_BUFFER_SIZE(ret, len, offset);
        }

        return offset;
}

static struct attr_policy osf_attr_policy[__NFTNL_EXPR_OSF_MAX] = {
        [NFTNL_EXPR_OSF_DREG]  = { .maxlen = sizeof(uint32_t) },
        [NFTNL_EXPR_OSF_TTL]   = { .maxlen = sizeof(uint8_t) },
        [NFTNL_EXPR_OSF_FLAGS] = { .maxlen = sizeof(uint32_t) },
};

struct expr_ops expr_ops_osf = {
        .name           = "osf",
        .alloc_len      = sizeof(struct nftnl_expr_osf),
        .nftnl_max_attr = __NFTNL_EXPR_OSF_MAX - 1,
        .attr_policy    = osf_attr_policy,
        .set            = nftnl_expr_osf_set,
        .get            = nftnl_expr_osf_get,
        .parse          = nftnl_expr_osf_parse,
        .build          = nftnl_expr_osf_build,
        .output         = nftnl_expr_osf_snprintf,
};