/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */

/*
 * NETLINK      Netlink attributes
 *
 * Copyright (c) 2003-2013 Thomas Graf <tgraf@suug.ch>
 */

#ifndef __LIBBPF_NLATTR_H
#define __LIBBPF_NLATTR_H

#include <stdint.h>
#include <string.h>
#include <errno.h>
#include <linux/netlink.h>
#include <linux/rtnetlink.h>
#include <linux/genetlink.h>

/* avoid multiple definition of netlink features */
#define __LINUX_NETLINK_H

/**
 * Standard attribute types to specify validation policy
 */
enum {
        LIBBPF_NLA_UNSPEC,      /**< Unspecified type, binary data chunk */
        LIBBPF_NLA_U8,          /**< 8 bit integer */
        LIBBPF_NLA_U16,         /**< 16 bit integer */
        LIBBPF_NLA_U32,         /**< 32 bit integer */
        LIBBPF_NLA_U64,         /**< 64 bit integer */
        LIBBPF_NLA_STRING,      /**< NUL terminated character string */
        LIBBPF_NLA_FLAG,        /**< Flag */
        LIBBPF_NLA_MSECS,       /**< Micro seconds (64bit) */
        LIBBPF_NLA_NESTED,      /**< Nested attributes */
        __LIBBPF_NLA_TYPE_MAX,
};

#define LIBBPF_NLA_TYPE_MAX (__LIBBPF_NLA_TYPE_MAX - 1)

/**
 * @ingroup attr
 * Attribute validation policy.
 *
 * See section @core_doc{core_attr_parse,Attribute Parsing} for more details.
 */
struct libbpf_nla_policy {
        /** Type of attribute or LIBBPF_NLA_UNSPEC */
        uint16_t        type;

        /** Minimal length of payload required */
        uint16_t        minlen;

        /** Maximal length of payload allowed */
        uint16_t        maxlen;
};

struct libbpf_nla_req {
        struct nlmsghdr nh;
        union {
                struct ifinfomsg ifinfo;
                struct tcmsg tc;
                struct genlmsghdr gnl;
        };
        char buf[128];
};

/**
 * @ingroup attr
 * Iterate over a stream of attributes
 * @arg pos     loop counter, set to current attribute
 * @arg head    head of attribute stream
 * @arg len     length of attribute stream
 * @arg rem     initialized to len, holds bytes currently remaining in stream
 */
#define libbpf_nla_for_each_attr(pos, head, len, rem) \
        for (pos = head, rem = len; \
             nla_ok(pos, rem); \
             pos = nla_next(pos, &(rem)))

/**
 * libbpf_nla_data - head of payload
 * @nla: netlink attribute
 */
static inline void *libbpf_nla_data(const struct nlattr *nla)
{
        return (void *)nla + NLA_HDRLEN;
}

static inline uint8_t libbpf_nla_getattr_u8(const struct nlattr *nla)
{
        return *(uint8_t *)libbpf_nla_data(nla);
}

static inline uint16_t libbpf_nla_getattr_u16(const struct nlattr *nla)
{
        return *(uint16_t *)libbpf_nla_data(nla);
}

static inline uint32_t libbpf_nla_getattr_u32(const struct nlattr *nla)
{
        return *(uint32_t *)libbpf_nla_data(nla);
}

static inline uint64_t libbpf_nla_getattr_u64(const struct nlattr *nla)
{
        return *(uint64_t *)libbpf_nla_data(nla);
}

static inline const char *libbpf_nla_getattr_str(const struct nlattr *nla)
{
        return (const char *)libbpf_nla_data(nla);
}

/**
 * libbpf_nla_len - length of payload
 * @nla: netlink attribute
 */
static inline int libbpf_nla_len(const struct nlattr *nla)
{
        return nla->nla_len - NLA_HDRLEN;
}

int libbpf_nla_parse(struct nlattr *tb[], int maxtype, struct nlattr *head,
                     int len, struct libbpf_nla_policy *policy);
int libbpf_nla_parse_nested(struct nlattr *tb[], int maxtype,
                            struct nlattr *nla,
                            struct libbpf_nla_policy *policy);

int libbpf_nla_dump_errormsg(struct nlmsghdr *nlh);

static inline struct nlattr *nla_data(struct nlattr *nla)
{
        return (struct nlattr *)((void *)nla + NLA_HDRLEN);
}

static inline struct nlattr *req_tail(struct libbpf_nla_req *req)
{
        return (struct nlattr *)((void *)req + NLMSG_ALIGN(req->nh.nlmsg_len));
}

static inline int nlattr_add(struct libbpf_nla_req *req, int type,
                             const void *data, int len)
{
        struct nlattr *nla;

        if (NLMSG_ALIGN(req->nh.nlmsg_len) + NLA_ALIGN(NLA_HDRLEN + len) > sizeof(*req))
                return -EMSGSIZE;
        if (!!data != !!len)
                return -EINVAL;

        nla = req_tail(req);
        nla->nla_type = type;
        nla->nla_len = NLA_HDRLEN + len;
        if (data)
                memcpy(nla_data(nla), data, len);
        req->nh.nlmsg_len = NLMSG_ALIGN(req->nh.nlmsg_len) + NLA_ALIGN(nla->nla_len);
        return 0;
}

static inline struct nlattr *nlattr_begin_nested(struct libbpf_nla_req *req, int type)
{
        struct nlattr *tail;

        tail = req_tail(req);
        if (nlattr_add(req, type | NLA_F_NESTED, NULL, 0))
                return NULL;
        return tail;
}

static inline void nlattr_end_nested(struct libbpf_nla_req *req,
                                     struct nlattr *tail)
{
        tail->nla_len = (void *)req_tail(req) - (void *)tail;
}

#endif /* __LIBBPF_NLATTR_H */