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sys/netlink/netlink_message_writer.h

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/*-
* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
*
* Copyright (c) 2021 Ng Peng Nam Sean
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* Copyright (c) 2022 Alexander V. Chernikov <melifaro@FreeBSD.org>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#ifndef _NETLINK_NETLINK_MESSAGE_WRITER_H_
#define _NETLINK_NETLINK_MESSAGE_WRITER_H_
/*
* It is not meant to be included directly
*/
struct mbuf;
struct nl_writer;
typedef bool nl_writer_cb(struct nl_writer *nw, void *buf, int buflen, int cnt);
struct nl_writer {
int alloc_len; /* allocated buffer length */
int offset; /* offset from the start of the buffer */
struct nlmsghdr *hdr; /* Pointer to the currently-filled msg */
char *data; /* pointer to the contiguous storage */
void *_storage; /* Underlying storage pointer */
nl_writer_cb *cb; /* Callback to flush data */
union {
void *arg_ptr; /* Callback argument as pointer */
uint64_t arg_uint; /* Callback argument as int */
};
int num_messages; /* Number of messages in the buffer */
int malloc_flag; /* M_WAITOK or M_NOWAIT */
uint8_t writer_type; /* NS_WRITER_TYPE_* */
uint8_t writer_target; /* NS_WRITER_TARGET_* */
bool ignore_limit; /* If true, ignores RCVBUF limit */
bool enomem; /* True if ENOMEM occured */
};
#define NS_WRITER_TARGET_SOCKET 0
#define NS_WRITER_TARGET_GROUP 1
#define NS_WRITER_TARGET_CHAIN 2
#define NS_WRITER_TYPE_MBUF 0
#define NS_WRITER_TYPE_BUF 1
#define NS_WRITER_TYPE_LBUF 2
#define NS_WRITER_TYPE_MBUFC 3
#define NLMSG_SMALL 128
#define NLMSG_LARGE 2048
/* Message and attribute writing */
struct nlpcb;
bool nlmsg_get_unicast_writer(struct nl_writer *nw, int expected_size, struct nlpcb *nlp);
bool nlmsg_get_group_writer(struct nl_writer *nw, int expected_size, int proto, int group_id);
bool nlmsg_get_chain_writer(struct nl_writer *nw, int expected_size, struct mbuf **pm);
bool nlmsg_flush(struct nl_writer *nw);
void nlmsg_ignore_limit(struct nl_writer *nw);
bool nlmsg_refill_buffer(struct nl_writer *nw, int required_size);
bool nlmsg_add(struct nl_writer *nw, uint32_t portid, uint32_t seq, uint16_t type,
uint16_t flags, uint32_t len);
bool nlmsg_end(struct nl_writer *nw);
void nlmsg_abort(struct nl_writer *nw);
bool nlmsg_end_dump(struct nl_writer *nw, int error, struct nlmsghdr *hdr);
static inline bool
nlmsg_reply(struct nl_writer *nw, const struct nlmsghdr *hdr, int payload_len)
{
return (nlmsg_add(nw, hdr->nlmsg_pid, hdr->nlmsg_seq, hdr->nlmsg_type,
hdr->nlmsg_flags, payload_len));
}
#define nlmsg_data(_hdr) ((void *)((_hdr) + 1))
/*
* KPI similar to mtodo():
* current (uncompleted) header is guaranteed to be contiguous,
* but can be reallocated, thus pointers may need to be readjusted.
*/
static inline int
nlattr_save_offset(const struct nl_writer *nw)
{
return (nw->offset - ((char *)nw->hdr - nw->data));
}
static inline void *
_nlattr_restore_offset(const struct nl_writer *nw, int off)
{
return ((void *)((char *)nw->hdr + off));
}
#define nlattr_restore_offset(_ns, _off, _t) ((_t *)_nlattr_restore_offset(_ns, _off))
static inline void
nlattr_set_len(const struct nl_writer *nw, int off)
{
struct nlattr *nla = nlattr_restore_offset(nw, off, struct nlattr);
nla->nla_len = nlattr_save_offset(nw) - off;
}
static inline void *
nlmsg_reserve_data_raw(struct nl_writer *nw, size_t sz)
{
if (__predict_false(nw->offset + NETLINK_ALIGN(sz) > nw->alloc_len)) {
if (!nlmsg_refill_buffer(nw, NETLINK_ALIGN(sz)))
return (NULL);
}
void *data_ptr = &nw->data[nw->offset];
nw->offset += NLMSG_ALIGN(sz);
return (data_ptr);
}
#define nlmsg_reserve_object(_ns, _t) ((_t *)nlmsg_reserve_data_raw(_ns, NLA_ALIGN(sizeof(_t))))
#define nlmsg_reserve_data(_ns, _sz, _t) ((_t *)nlmsg_reserve_data_raw(_ns, _sz))
static inline int
nlattr_add_nested(struct nl_writer *nw, uint16_t nla_type)
{
int off = nlattr_save_offset(nw);
struct nlattr *nla = nlmsg_reserve_data(nw, sizeof(struct nlattr), struct nlattr);
if (__predict_false(nla == NULL))
return (0);
nla->nla_type = nla_type;
return (off);
}
static inline void *
_nlmsg_reserve_attr(struct nl_writer *nw, uint16_t nla_type, uint16_t sz)
{
sz += sizeof(struct nlattr);
struct nlattr *nla = nlmsg_reserve_data(nw, sz, struct nlattr);
if (__predict_false(nla == NULL))
return (NULL);
nla->nla_type = nla_type;
nla->nla_len = sz;
return ((void *)(nla + 1));
}
#define nlmsg_reserve_attr(_ns, _at, _t) ((_t *)_nlmsg_reserve_attr(_ns, _at, NLA_ALIGN(sizeof(_t))))
static inline bool
nlattr_add(struct nl_writer *nw, int attr_type, int attr_len, const void *data)
{
int required_len = NLA_ALIGN(attr_len + sizeof(struct nlattr));
if (__predict_false(nw->offset + required_len > nw->alloc_len)) {
if (!nlmsg_refill_buffer(nw, required_len))
return (false);
}
struct nlattr *nla = (struct nlattr *)(&nw->data[nw->offset]);
nla->nla_len = attr_len + sizeof(struct nlattr);
nla->nla_type = attr_type;
if (attr_len > 0) {
if ((attr_len % 4) != 0) {
/* clear padding bytes */
bzero((char *)nla + required_len - 4, 4);
}
memcpy((nla + 1), data, attr_len);
}
nw->offset += required_len;
return (true);
}
static inline bool
nlattr_add_u8(struct nl_writer *nw, int attrtype, uint8_t value)
{
return (nlattr_add(nw, attrtype, sizeof(uint8_t), &value));
}
static inline bool
nlattr_add_u16(struct nl_writer *nw, int attrtype, uint16_t value)
{
return (nlattr_add(nw, attrtype, sizeof(uint16_t), &value));
}
static inline bool
nlattr_add_u32(struct nl_writer *nw, int attrtype, uint32_t value)
{
return (nlattr_add(nw, attrtype, sizeof(uint32_t), &value));
}
static inline bool
nlattr_add_u64(struct nl_writer *nw, int attrtype, uint64_t value)
{
return (nlattr_add(nw, attrtype, sizeof(uint64_t), &value));
}
static inline bool
nlattr_add_s8(struct nl_writer *nw, int attrtype, int8_t value)
{
return (nlattr_add(nw, attrtype, sizeof(int8_t), &value));
}
static inline bool
nlattr_add_s16(struct nl_writer *nw, int attrtype, int16_t value)
{
return (nlattr_add(nw, attrtype, sizeof(int16_t), &value));
}
static inline bool
nlattr_add_s32(struct nl_writer *nw, int attrtype, int32_t value)
{
return (nlattr_add(nw, attrtype, sizeof(int32_t), &value));
}
static inline bool
nlattr_add_s64(struct nl_writer *nw, int attrtype, int64_t value)
{
return (nlattr_add(nw, attrtype, sizeof(int64_t), &value));
}
static inline bool
nlattr_add_flag(struct nl_writer *nw, int attrtype)
{
return (nlattr_add(nw, attrtype, 0, NULL));
}
static inline bool
nlattr_add_string(struct nl_writer *nw, int attrtype, const char *str)
{
return (nlattr_add(nw, attrtype, strlen(str) + 1, str));
}
#endif