attr.c

/*
 * (C) 2008-2010 by Pablo Neira Ayuso <pablo@netfilter.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published
 * by the Free Software Foundation; either version 2.1 of the License, or
 * (at your option) any later version.
 */

#include <libmnl/libmnl.h>
#include <string.h>
#include <values.h>     /* for INT_MAX */
#include <errno.h>
#include "internal.h"

EXPORT_SYMBOL uint16_t mnl_attr_get_type(const struct nlattr *attr)
{
        return attr->nla_type & NLA_TYPE_MASK;
}

EXPORT_SYMBOL uint16_t mnl_attr_get_len(const struct nlattr *attr)
{
        return attr->nla_len;
}

EXPORT_SYMBOL uint16_t mnl_attr_get_payload_len(const struct nlattr *attr)
{
        return attr->nla_len - MNL_ATTR_HDRLEN;
}

EXPORT_SYMBOL void *mnl_attr_get_payload(const struct nlattr *attr)
{
        return (void *)attr + MNL_ATTR_HDRLEN;
}

EXPORT_SYMBOL bool mnl_attr_ok(const struct nlattr *attr, int len)
{
        return len >= (int)sizeof(struct nlattr) &&
               attr->nla_len >= sizeof(struct nlattr) &&
               (int)attr->nla_len <= len;
}

EXPORT_SYMBOL struct nlattr *mnl_attr_next(const struct nlattr *attr)
{
        return (struct nlattr *)((void *)attr + MNL_ALIGN(attr->nla_len));
}

EXPORT_SYMBOL int mnl_attr_type_valid(const struct nlattr *attr, uint16_t max)
{
        if (mnl_attr_get_type(attr) > max) {
                errno = EOPNOTSUPP;
                return -1;
        }
        return 1;
}

static int __mnl_attr_validate(const struct nlattr *attr,
                               enum mnl_attr_data_type type, size_t exp_len)
{
        uint16_t attr_len = mnl_attr_get_payload_len(attr);
        const char *attr_data = mnl_attr_get_payload(attr);

        if (attr_len < exp_len) {
                errno = ERANGE;
                return -1;
        }
        switch(type) {
        case MNL_TYPE_FLAG:
                if (attr_len > 0) {
                        errno = ERANGE;
                        return -1;
                }
                break;
        case MNL_TYPE_NUL_STRING:
                if (attr_len == 0) {
                        errno = ERANGE;
                        return -1;
                }
                if (attr_data[attr_len-1] != '\0') {
                        errno = EINVAL;
                        return -1;
                }
                break;
        case MNL_TYPE_STRING:
                if (attr_len == 0) {
                        errno = ERANGE;
                        return -1;
                }
                break;
        case MNL_TYPE_NESTED:
                /* empty nested attributes are OK. */
                if (attr_len == 0)
                        break;
                /* if not empty, they must contain one header, eg. flag */
                if (attr_len < MNL_ATTR_HDRLEN) {
                        errno = ERANGE;
                        return -1;
                }
                break;
        default:
                /* make gcc happy. */
                break;
        }
        if (exp_len && attr_len > exp_len) {
                errno = ERANGE;
                return -1;
        }
        return 0;
}

static const size_t mnl_attr_data_type_len[MNL_TYPE_MAX] = {
        [MNL_TYPE_U8]           = sizeof(uint8_t),
        [MNL_TYPE_U16]          = sizeof(uint16_t),
        [MNL_TYPE_U32]          = sizeof(uint32_t),
        [MNL_TYPE_U64]          = sizeof(uint64_t),
};

EXPORT_SYMBOL int
mnl_attr_validate(const struct nlattr *attr, enum mnl_attr_data_type type)
{
        int exp_len;

        if (type >= MNL_TYPE_MAX) {
                errno = EINVAL;
                return -1;
        }
        exp_len = mnl_attr_data_type_len[type];
        return __mnl_attr_validate(attr, type, exp_len);
}

EXPORT_SYMBOL int
mnl_attr_validate2(const struct nlattr *attr, enum mnl_attr_data_type type,
                   size_t exp_len)
{
        if (type >= MNL_TYPE_MAX) {
                errno = EINVAL;
                return -1;
        }
        return __mnl_attr_validate(attr, type, exp_len);
}

EXPORT_SYMBOL int
mnl_attr_parse(const struct nlmsghdr *nlh, unsigned int offset,
               mnl_attr_cb_t cb, void *data)
{
        int ret = MNL_CB_OK;
        const struct nlattr *attr;

        mnl_attr_for_each(attr, nlh, offset)
                if ((ret = cb(attr, data)) <= MNL_CB_STOP)
                        return ret;
        return ret;
}

EXPORT_SYMBOL int
mnl_attr_parse_nested(const struct nlattr *nested, mnl_attr_cb_t cb,
                      void *data)
{
        int ret = MNL_CB_OK;
        const struct nlattr *attr;

        mnl_attr_for_each_nested(attr, nested)
                if ((ret = cb(attr, data)) <= MNL_CB_STOP)
                        return ret;
        return ret;
}

EXPORT_SYMBOL uint8_t mnl_attr_get_u8(const struct nlattr *attr)
{
        return *((uint8_t *)mnl_attr_get_payload(attr));
}

EXPORT_SYMBOL uint16_t mnl_attr_get_u16(const struct nlattr *attr)
{
        return *((uint16_t *)mnl_attr_get_payload(attr));
}

EXPORT_SYMBOL uint32_t mnl_attr_get_u32(const struct nlattr *attr)
{
        return *((uint32_t *)mnl_attr_get_payload(attr));
}

EXPORT_SYMBOL uint64_t mnl_attr_get_u64(const struct nlattr *attr)
{
        uint64_t tmp;
        memcpy(&tmp, mnl_attr_get_payload(attr), sizeof(tmp));
        return tmp;
}

EXPORT_SYMBOL const char *mnl_attr_get_str(const struct nlattr *attr)
{
        return mnl_attr_get_payload(attr);
}

EXPORT_SYMBOL void
mnl_attr_put(struct nlmsghdr *nlh, uint16_t type, size_t len, const void *data)
{
        struct nlattr *attr = mnl_nlmsg_get_payload_tail(nlh);
        uint16_t payload_len = MNL_ALIGN(sizeof(struct nlattr)) + len;

        attr->nla_type = type;
        attr->nla_len = payload_len;
        memcpy(mnl_attr_get_payload(attr), data, len);
        nlh->nlmsg_len += MNL_ALIGN(payload_len);
}

EXPORT_SYMBOL void
mnl_attr_put_u8(struct nlmsghdr *nlh, uint16_t type, uint8_t data)
{
        mnl_attr_put(nlh, type, sizeof(uint8_t), &data);
}

EXPORT_SYMBOL void
mnl_attr_put_u16(struct nlmsghdr *nlh, uint16_t type, uint16_t data)
{
        mnl_attr_put(nlh, type, sizeof(uint16_t), &data);
}

EXPORT_SYMBOL void
mnl_attr_put_u32(struct nlmsghdr *nlh, uint16_t type, uint32_t data)
{
        mnl_attr_put(nlh, type, sizeof(uint32_t), &data);
}

EXPORT_SYMBOL void
mnl_attr_put_u64(struct nlmsghdr *nlh, uint16_t type, uint64_t data)
{
        mnl_attr_put(nlh, type, sizeof(uint64_t), &data);
}

EXPORT_SYMBOL void
mnl_attr_put_str(struct nlmsghdr *nlh, uint16_t type, const char *data)
{
        mnl_attr_put(nlh, type, strlen(data), data);
}

EXPORT_SYMBOL void
mnl_attr_put_strz(struct nlmsghdr *nlh, uint16_t type, const char *data)
{
        mnl_attr_put(nlh, type, strlen(data)+1, data);
}

EXPORT_SYMBOL struct nlattr *
mnl_attr_nest_start(struct nlmsghdr *nlh, uint16_t type)
{
        struct nlattr *start = mnl_nlmsg_get_payload_tail(nlh);

        /* set start->nla_len in mnl_attr_nest_end() */
        start->nla_type = NLA_F_NESTED | type;
        nlh->nlmsg_len += MNL_ALIGN(sizeof(struct nlattr));

        return start;
}

EXPORT_SYMBOL bool
mnl_attr_put_check(struct nlmsghdr *nlh, size_t buflen,
                   uint16_t type, size_t len, const void *data)
{
        if (nlh->nlmsg_len + MNL_ATTR_HDRLEN + MNL_ALIGN(len) > buflen)
                return false;
        mnl_attr_put(nlh, type, len, data);
        return true;
}

EXPORT_SYMBOL bool
mnl_attr_put_u8_check(struct nlmsghdr *nlh, size_t buflen,
                      uint16_t type, uint8_t data)
{
        return mnl_attr_put_check(nlh, buflen, type, sizeof(uint8_t), &data);
}

EXPORT_SYMBOL bool
mnl_attr_put_u16_check(struct nlmsghdr *nlh, size_t buflen,
                       uint16_t type, uint16_t data)
{
        return mnl_attr_put_check(nlh, buflen, type, sizeof(uint16_t), &data);
}

EXPORT_SYMBOL bool
mnl_attr_put_u32_check(struct nlmsghdr *nlh, size_t buflen,
                       uint16_t type, uint32_t data)
{
        return mnl_attr_put_check(nlh, buflen, type, sizeof(uint32_t), &data);
}

EXPORT_SYMBOL bool
mnl_attr_put_u64_check(struct nlmsghdr *nlh, size_t buflen,
                       uint16_t type, uint64_t data)
{
        return mnl_attr_put_check(nlh, buflen, type, sizeof(uint64_t), &data);
}

EXPORT_SYMBOL bool
mnl_attr_put_str_check(struct nlmsghdr *nlh, size_t buflen,
                       uint16_t type, const char *data)
{
        return mnl_attr_put_check(nlh, buflen, type, strlen(data), data);
}

EXPORT_SYMBOL bool
mnl_attr_put_strz_check(struct nlmsghdr *nlh, size_t buflen,
                        uint16_t type, const char *data)
{
        return mnl_attr_put_check(nlh, buflen, type, strlen(data)+1, data);
}

EXPORT_SYMBOL struct nlattr *
mnl_attr_nest_start_check(struct nlmsghdr *nlh, size_t buflen, uint16_t type)
{
        if (nlh->nlmsg_len + MNL_ATTR_HDRLEN > buflen)
                return NULL;
        return mnl_attr_nest_start(nlh, type);
}

EXPORT_SYMBOL void
mnl_attr_nest_end(struct nlmsghdr *nlh, struct nlattr *start)
{
        start->nla_len = mnl_nlmsg_get_payload_tail(nlh) - (void *)start;
}

EXPORT_SYMBOL void
mnl_attr_nest_cancel(struct nlmsghdr *nlh, struct nlattr *start)
{
        nlh->nlmsg_len -= mnl_nlmsg_get_payload_tail(nlh) - (void *)start;
}