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36f1678d9e
This patch added a few netlink attribute parsing functions
and the netlink API functions to query networking links, tc classes,
tc qdiscs and tc filters. For example, the following API is
to get networking links:
int nl_get_link(int sock, unsigned int nl_pid,
dump_nlmsg_t dump_link_nlmsg,
void *cookie);
Note that when the API is called, the user also provided a
callback function with the following signature:
int (*dump_nlmsg_t)(void *cookie, void *msg, struct nlattr **tb);
The "cookie" is the parameter the user passed to the API and will
be available for the callback function.
The "msg" is the information about the result, e.g., ifinfomsg or
tcmsg. The "tb" is the parsed netlink attributes.
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
111 lines
2.6 KiB
C
111 lines
2.6 KiB
C
/* SPDX-License-Identifier: LGPL-2.1 */
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/*
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* NETLINK Netlink attributes
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation version 2.1
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* of the License.
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*
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* Copyright (c) 2003-2013 Thomas Graf <tgraf@suug.ch>
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*/
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#ifndef __NLATTR_H
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#define __NLATTR_H
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#include <stdint.h>
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#include <linux/netlink.h>
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/* avoid multiple definition of netlink features */
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#define __LINUX_NETLINK_H
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/**
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* Standard attribute types to specify validation policy
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*/
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enum {
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NLA_UNSPEC, /**< Unspecified type, binary data chunk */
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NLA_U8, /**< 8 bit integer */
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NLA_U16, /**< 16 bit integer */
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NLA_U32, /**< 32 bit integer */
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NLA_U64, /**< 64 bit integer */
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NLA_STRING, /**< NUL terminated character string */
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NLA_FLAG, /**< Flag */
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NLA_MSECS, /**< Micro seconds (64bit) */
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NLA_NESTED, /**< Nested attributes */
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__NLA_TYPE_MAX,
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};
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#define NLA_TYPE_MAX (__NLA_TYPE_MAX - 1)
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/**
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* @ingroup attr
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* Attribute validation policy.
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*
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* See section @core_doc{core_attr_parse,Attribute Parsing} for more details.
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*/
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struct nla_policy {
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/** Type of attribute or NLA_UNSPEC */
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uint16_t type;
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/** Minimal length of payload required */
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uint16_t minlen;
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/** Maximal length of payload allowed */
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uint16_t maxlen;
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};
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/**
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* @ingroup attr
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* Iterate over a stream of attributes
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* @arg pos loop counter, set to current attribute
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* @arg head head of attribute stream
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* @arg len length of attribute stream
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* @arg rem initialized to len, holds bytes currently remaining in stream
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*/
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#define nla_for_each_attr(pos, head, len, rem) \
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for (pos = head, rem = len; \
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nla_ok(pos, rem); \
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pos = nla_next(pos, &(rem)))
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/**
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* nla_data - head of payload
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* @nla: netlink attribute
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*/
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static inline void *nla_data(const struct nlattr *nla)
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{
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return (char *) nla + NLA_HDRLEN;
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}
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static inline uint8_t nla_getattr_u8(const struct nlattr *nla)
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{
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return *(uint8_t *)nla_data(nla);
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}
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static inline uint32_t nla_getattr_u32(const struct nlattr *nla)
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{
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return *(uint32_t *)nla_data(nla);
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}
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static inline const char *nla_getattr_str(const struct nlattr *nla)
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{
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return (const char *)nla_data(nla);
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}
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/**
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* nla_len - length of payload
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* @nla: netlink attribute
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*/
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static inline int nla_len(const struct nlattr *nla)
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{
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return nla->nla_len - NLA_HDRLEN;
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}
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int nla_parse(struct nlattr *tb[], int maxtype, struct nlattr *head, int len,
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struct nla_policy *policy);
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int nla_parse_nested(struct nlattr *tb[], int maxtype, struct nlattr *nla,
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struct nla_policy *policy);
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int nla_dump_errormsg(struct nlmsghdr *nlh);
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#endif /* __NLATTR_H */
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