/* -*- Mode: C; tab-width: 4; indent-tabs-mode: t; c-basic-offset: 4 -*- */
/* nm-platform.c - Handle runtime kernel networking configuration
 *
 * 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, or (at your option)
 * any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Copyright (C) 2018 Red Hat, Inc.
 */

#ifndef __NM_NETLINK_H__
#define __NM_NETLINK_H__

#include <linux/netlink.h>
#include <linux/rtnetlink.h>
#include <linux/genetlink.h>

/*****************************************************************************/
#define _NLE_BASE               100000
#define NLE_UNSPEC              (_NLE_BASE +  0)
#define NLE_BUG                 (_NLE_BASE +  1)
#define NLE_NATIVE_ERRNO        (_NLE_BASE +  2)
#define NLE_SEQ_MISMATCH        (_NLE_BASE +  3)
#define NLE_MSG_TRUNC           (_NLE_BASE +  4)
#define NLE_MSG_TOOSHORT        (_NLE_BASE +  5)
#define NLE_DUMP_INTR           (_NLE_BASE +  6)
#define NLE_ATTRSIZE            (_NLE_BASE +  7)
#define NLE_BAD_SOCK            (_NLE_BASE +  8)
#define NLE_NOADDR              (_NLE_BASE +  9)
#define NLE_MSG_OVERFLOW        (_NLE_BASE + 10)

#define _NLE_BASE_END           (_NLE_BASE + 11)

#define NLMSGERR_ATTR_UNUSED            0
#define NLMSGERR_ATTR_MSG               1
#define NLMSGERR_ATTR_OFFS              2
#define NLMSGERR_ATTR_COOKIE            3
#define NLMSGERR_ATTR_MAX               3

#ifndef NLM_F_ACK_TLVS
#define NLM_F_ACK_TLVS                  0x200
#endif

static inline int
nl_errno (int err)
{
	/* the error codes from our netlink implementation are plain errno
	 * extended with our own error in a particular range starting from
	 * _NLE_BASE.
	 *
	 * However, often we encode errors as negative values. This function
	 * normalizes the error and returns it's positive value. */
	return err >= 0
	       ? err
	       : ((err == G_MININT) ? NLE_BUG : -errno);
}

static inline int
nl_syserr2nlerr (int err)
{
	if (err == G_MININT)
		return NLE_NATIVE_ERRNO;
	if (err < 0)
		err = -err;
	return (err >= _NLE_BASE && err < _NLE_BASE_END)
	       ? NLE_NATIVE_ERRNO
	       : err;
}

const char *nl_geterror (int err);

/*****************************************************************************/

/* Basic attribute data types */
enum {
	NLA_UNSPEC,     /* Unspecified type, binary data chunk */
	NLA_U8,         /* 8 bit integer */
	NLA_U16,        /* 16 bit integer */
	NLA_U32,        /* 32 bit integer */
	NLA_U64,        /* 64 bit integer */
	NLA_STRING,     /* NUL terminated character string */
	NLA_FLAG,       /* Flag */
	NLA_MSECS,      /* Micro seconds (64bit) */
	NLA_NESTED,     /* Nested attributes */
	NLA_NESTED_COMPAT,
	NLA_NUL_STRING,
	NLA_BINARY,
	NLA_S8,
	NLA_S16,
	NLA_S32,
	NLA_S64,
	__NLA_TYPE_MAX,
};

#define NLA_TYPE_MAX (__NLA_TYPE_MAX - 1)

struct nl_msg;

/*****************************************************************************/

const char *nl_nlmsgtype2str (int type, char *buf, size_t size);

const char *nl_nlmsg_flags2str (int flags, char *buf, size_t len);

const char *nl_nlmsghdr_to_str (const struct nlmsghdr *hdr, char *buf, gsize len);

/*****************************************************************************/

struct nla_policy {
	/* Type of attribute or NLA_UNSPEC */
	uint16_t type;

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

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

/*****************************************************************************/

static inline int
nla_attr_size(int payload)
{
	nm_assert (payload >= 0);

	return NLA_HDRLEN + payload;
}

static inline int
nla_total_size (int payload)
{
	return NLA_ALIGN (nla_attr_size (payload));
}

static inline int
nla_padlen (int payload)
{
	return nla_total_size(payload) - nla_attr_size(payload);
}

struct nlattr *nla_reserve (struct nl_msg *msg, int attrtype, int attrlen);

static inline int
nla_len (const struct nlattr *nla)
{
	return nla->nla_len - NLA_HDRLEN;
}

static inline int
nla_type (const struct nlattr *nla)
{
	return nla->nla_type & NLA_TYPE_MASK;
}

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

static inline uint8_t
nla_get_u8 (const struct nlattr *nla)
{
	return *(const uint8_t *) nla_data (nla);
}

static inline uint16_t
nla_get_u16 (const struct nlattr *nla)
{
	return *(const uint16_t *) nla_data (nla);
}

static inline uint32_t
nla_get_u32(const struct nlattr *nla)
{
	return *(const uint32_t *) nla_data (nla);
}

uint64_t nla_get_u64 (const struct nlattr *nla);

static inline char *
nla_get_string (const struct nlattr *nla)
{
	return (char *) nla_data (nla);
}

size_t nla_strlcpy (char *dst, const struct nlattr *nla, size_t dstsize);

int nla_memcpy (void *dest, const struct nlattr *src, int count);

int nla_put (struct nl_msg *msg, int attrtype, int datalen, const void *data);

static inline int
nla_put_string (struct nl_msg *msg, int attrtype, const char *str)
{
	return nla_put(msg, attrtype, strlen(str) + 1, str);
}

#define NLA_PUT(msg, attrtype, attrlen, data) \
	do { \
		if (nla_put(msg, attrtype, attrlen, data) < 0) \
			goto nla_put_failure; \
	} while(0)

#define NLA_PUT_TYPE(msg, type, attrtype, value) \
	do { \
		type __tmp = value; \
		NLA_PUT(msg, attrtype, sizeof(type), &__tmp); \
	} while(0)

#define NLA_PUT_U8(msg, attrtype, value) \
	NLA_PUT_TYPE(msg, uint8_t, attrtype, value)

#define NLA_PUT_U16(msg, attrtype, value) \
	NLA_PUT_TYPE(msg, uint16_t, attrtype, value)

#define NLA_PUT_U32(msg, attrtype, value) \
	NLA_PUT_TYPE(msg, uint32_t, attrtype, value)

#define NLA_PUT_U64(msg, attrtype, value) \
	NLA_PUT_TYPE(msg, uint64_t, attrtype, value)

#define NLA_PUT_STRING(msg, attrtype, value) \
	NLA_PUT(msg, attrtype, (int) strlen(value) + 1, value)

struct nlattr *nla_find (const struct nlattr *head, int len, int attrtype);

static inline int
nla_ok (const struct nlattr *nla, int remaining)
{
	return remaining >= sizeof(*nla) &&
	       nla->nla_len >= sizeof(*nla) &&
	       nla->nla_len <= remaining;
}

static inline struct nlattr *
nla_next(const struct nlattr *nla, int *remaining)
{
	int totlen = NLA_ALIGN(nla->nla_len);

	*remaining -= totlen;
	return (struct nlattr *) ((char *) nla + totlen);
}

#define nla_for_each_attr(pos, head, len, rem) \
	for (pos = head, rem = len; \
	     nla_ok(pos, rem); \
	     pos = nla_next(pos, &(rem)))

#define nla_for_each_nested(pos, nla, rem) \
	for (pos = (struct nlattr *) nla_data(nla), rem = nla_len(nla); \
	     nla_ok(pos, rem); \
	     pos = nla_next(pos, &(rem)))

void nla_nest_cancel (struct nl_msg *msg, const struct nlattr *attr);
struct nlattr *nla_nest_start (struct nl_msg *msg, int attrtype);
int nla_nest_end (struct nl_msg *msg, struct nlattr *start);

int nla_parse (struct nlattr *tb[], int maxtype, struct nlattr *head, int len,
               const struct nla_policy *policy);

static inline int
nla_parse_nested (struct nlattr *tb[], int maxtype, struct nlattr *nla,
                  const struct nla_policy *policy)
{
	return nla_parse (tb, maxtype, nla_data(nla), nla_len(nla), policy);
}

/*****************************************************************************/

struct nl_msg *nlmsg_alloc (void);

struct nl_msg *nlmsg_alloc_size (size_t max);

struct nl_msg *nlmsg_alloc_inherit (struct nlmsghdr *hdr);

struct nl_msg *nlmsg_alloc_convert (struct nlmsghdr *hdr);

struct nl_msg *nlmsg_alloc_simple (int nlmsgtype, int flags);

void *nlmsg_reserve (struct nl_msg *n, size_t len, int pad);

int nlmsg_append (struct nl_msg *n, void *data, size_t len, int pad);

void nlmsg_free (struct nl_msg *msg);

static inline int
nlmsg_size (int payload)
{
	nm_assert (payload >= 0 && payload < G_MAXINT - NLMSG_HDRLEN - 4);
	return NLMSG_HDRLEN + payload;
}

static inline int
nlmsg_total_size (int payload)
{
	return NLMSG_ALIGN (nlmsg_size (payload));
}

static inline int
nlmsg_ok (const struct nlmsghdr *nlh, int remaining)
{
	return (remaining >= (int)sizeof(struct nlmsghdr) &&
	       nlh->nlmsg_len >= sizeof(struct nlmsghdr) &&
	       nlh->nlmsg_len <= remaining);
}

static inline struct nlmsghdr *
nlmsg_next (struct nlmsghdr *nlh, int *remaining)
{
	int totlen = NLMSG_ALIGN(nlh->nlmsg_len);

	*remaining -= totlen;

	return (struct nlmsghdr *) ((unsigned char *) nlh + totlen);
}

int nlmsg_get_proto (struct nl_msg *msg);
void nlmsg_set_proto (struct nl_msg *msg, int protocol);

void nlmsg_set_src (struct nl_msg *msg, struct sockaddr_nl *addr);

struct ucred *nlmsg_get_creds (struct nl_msg *msg);
void nlmsg_set_creds (struct nl_msg *msg, struct ucred *creds);

static inline void
_nm_auto_nl_msg_cleanup (struct nl_msg **ptr)
{
	nlmsg_free (*ptr);
}
#define nm_auto_nlmsg nm_auto(_nm_auto_nl_msg_cleanup)

static inline void *
nlmsg_data (const struct nlmsghdr *nlh)
{
	return (unsigned char *) nlh + NLMSG_HDRLEN;
}

static inline void *
nlmsg_tail (const struct nlmsghdr *nlh)
{
	return (unsigned char *) nlh + NLMSG_ALIGN(nlh->nlmsg_len);
}

struct nlmsghdr *nlmsg_hdr (struct nl_msg *n);

static inline int
nlmsg_valid_hdr(const struct nlmsghdr *nlh, int hdrlen)
{
	if (nlh->nlmsg_len < nlmsg_size (hdrlen))
		return 0;

	return 1;
}

static inline int
nlmsg_datalen (const struct nlmsghdr *nlh)
{
	return nlh->nlmsg_len - NLMSG_HDRLEN;
}

static inline int
nlmsg_attrlen (const struct nlmsghdr *nlh, int hdrlen)
{
	return NM_MAX ((int) (nlmsg_datalen (nlh) - NLMSG_ALIGN (hdrlen)), 0);
}

static inline struct nlattr *
nlmsg_attrdata (const struct nlmsghdr *nlh, int hdrlen)
{
	unsigned char *data = nlmsg_data(nlh);
	return (struct nlattr *) (data + NLMSG_ALIGN(hdrlen));
}

static inline struct nlattr *
nlmsg_find_attr (struct nlmsghdr *nlh, int hdrlen, int attrtype)
{
	return nla_find (nlmsg_attrdata (nlh, hdrlen),
	                 nlmsg_attrlen (nlh, hdrlen),
	                 attrtype);
}

int nlmsg_parse (struct nlmsghdr *nlh, int hdrlen, struct nlattr *tb[],
                 int maxtype, const struct nla_policy *policy);

struct nlmsghdr *nlmsg_put (struct nl_msg *n, uint32_t pid, uint32_t seq,
                            int type, int payload, int flags);

/*****************************************************************************/

void *genlmsg_put (struct nl_msg *msg, uint32_t port, uint32_t seq, int family,
                   int hdrlen, int flags, uint8_t cmd, uint8_t version);
void *genlmsg_data (const struct genlmsghdr *gnlh);
void *genlmsg_user_hdr (const struct genlmsghdr *gnlh);
struct genlmsghdr *genlmsg_hdr (struct nlmsghdr *nlh);
void *genlmsg_user_data (const struct genlmsghdr *gnlh, const int hdrlen);
struct nlattr *genlmsg_attrdata (const struct genlmsghdr *gnlh, int hdrlen);
int genlmsg_len (const struct genlmsghdr *gnlh);
int genlmsg_attrlen (const struct genlmsghdr *gnlh, int hdrlen);
int genlmsg_valid_hdr (struct nlmsghdr *nlh, int hdrlen);
int genlmsg_parse (struct nlmsghdr *nlh, int hdrlen, struct nlattr *tb[],
                   int maxtype, const struct nla_policy *policy);

/*****************************************************************************/

#define NL_AUTO_PORT 0
#define NL_AUTO_SEQ  0

struct nl_sock;

struct nl_sock *nl_socket_alloc (void);

void nl_socket_free (struct nl_sock *sk);

int nl_socket_get_fd (const struct nl_sock *sk);

struct sockaddr_nl *nlmsg_get_dst (struct nl_msg *msg);

size_t nl_socket_get_msg_buf_size (struct nl_sock *sk);
int nl_socket_set_msg_buf_size (struct nl_sock *sk, size_t bufsize);

int nl_socket_set_buffer_size (struct nl_sock *sk, int rxbuf, int txbuf);

int nl_socket_set_passcred (struct nl_sock *sk, int state);

int nl_socket_set_nonblocking (const struct nl_sock *sk);

void nl_socket_disable_msg_peek (struct nl_sock *sk);

uint32_t nl_socket_get_local_port (const struct nl_sock *sk);

int nl_socket_add_memberships (struct nl_sock *sk, int group, ...);

int nl_connect (struct nl_sock *sk, int protocol);

int nl_recv (struct nl_sock *sk, struct sockaddr_nl *nla,
             unsigned char **buf, struct ucred **creds);

int nl_send (struct nl_sock *sk, struct nl_msg *msg);

int nl_send_auto (struct nl_sock *sk, struct nl_msg *msg);

/*****************************************************************************/

enum nl_cb_action {
	/* Proceed with wathever would come next */
	NL_OK,
	/* Skip this message */
	NL_SKIP,
	/* Stop parsing altogether and discard remaining messages */
	NL_STOP,
};

typedef int (*nl_recvmsg_msg_cb_t) (struct nl_msg *msg, void *arg);

typedef int (*nl_recvmsg_err_cb_t) (struct sockaddr_nl *nla,
                                    struct nlmsgerr *nlerr, void *arg);

struct nl_cb {
	nl_recvmsg_msg_cb_t     valid_cb;
	void *                  valid_arg;

	nl_recvmsg_msg_cb_t     finish_cb;
	void *                  finish_arg;

	nl_recvmsg_msg_cb_t     ack_cb;
	void *                  ack_arg;

	nl_recvmsg_err_cb_t     err_cb;
	void *                  err_arg;
};

int nl_sendmsg (struct nl_sock *sk, struct nl_msg *msg, struct msghdr *hdr);

int nl_send_iovec (struct nl_sock *sk, struct nl_msg *msg, struct iovec *iov, unsigned iovlen);

void nl_complete_msg (struct nl_sock *sk, struct nl_msg *msg);

int nl_recvmsgs (struct nl_sock *sk, const struct nl_cb *cb);

int nl_wait_for_ack (struct nl_sock *sk,
                     const struct nl_cb *cb);

int nl_socket_set_ext_ack (struct nl_sock *sk, gboolean enable);

/*****************************************************************************/

#endif /* __NM_NETLINK_H__ */