2 * netlink/cache-api.h Caching API
4 * This library is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU Lesser General Public
6 * License as published by the Free Software Foundation version 2.1
9 * Copyright (c) 2003-2006 Thomas Graf <tgraf@suug.ch>
12 #ifndef NETLINK_CACHE_API_H_
13 #define NETLINK_CACHE_API_H_
15 #include <netlink/netlink.h>
23 * @defgroup cache_api Cache Implementation
26 * @par 1) Cache Definition
28 * struct nl_cache_ops my_cache_ops = {
29 * .co_name = "route/link",
30 * .co_protocol = NETLINK_ROUTE,
31 * .co_hdrsize = sizeof(struct ifinfomsg),
32 * .co_obj_ops = &my_obj_ops,
38 * // The simplest way to fill a cache is by providing a request-update
39 * // function which must trigger a complete dump on the kernel-side of
40 * // whatever the cache covers.
41 * static int my_request_update(struct nl_cache *cache,
42 * struct nl_sock *socket)
44 * // In this example, we request a full dump of the interface table
45 * return nl_rtgen_request(socket, RTM_GETLINK, AF_UNSPEC, NLM_F_DUMP);
48 * // The resulting netlink messages sent back will be fed into a message
49 * // parser one at a time. The message parser has to extract all relevant
50 * // information from the message and create an object reflecting the
51 * // contents of the message and pass it on to the parser callback function
52 * // provide which will add the object to the cache.
53 * static int my_msg_parser(struct nl_cache_ops *ops, struct sockaddr_nl *who,
54 * struct nlmsghdr *nlh, struct nl_parser_param *pp)
58 * obj = my_obj_alloc();
59 * obj->ce_msgtype = nlh->nlmsg_type;
61 * // Parse the netlink message and continue creating the object.
63 * err = pp->pp_cb((struct nl_object *) obj, pp);
68 * struct nl_cache_ops my_cache_ops = {
70 * .co_request_update = my_request_update,
71 * .co_msg_parser = my_msg_parser,
75 * @par 3) Notification based Updates
77 * // Caches can be kept up-to-date based on notifications if the kernel
78 * // sends out notifications whenever an object is added/removed/changed.
80 * // It is trivial to support this, first a list of groups needs to be
81 * // defined which are required to join in order to receive all necessary
82 * // notifications. The groups are separated by address family to support
83 * // the common situation where a separate group is used for each address
84 * // family. If there is only one group, simply specify AF_UNSPEC.
85 * static struct nl_af_group addr_groups[] = {
86 * { AF_INET, RTNLGRP_IPV4_IFADDR },
87 * { AF_INET6, RTNLGRP_IPV6_IFADDR },
88 * { END_OF_GROUP_LIST },
91 * // In order for the caching system to know the meaning of each message
92 * // type it requires a table which maps each supported message type to
93 * // a cache action, e.g. RTM_NEWADDR means address has been added or
94 * // updated, RTM_DELADDR means address has been removed.
95 * static struct nl_cache_ops rtnl_addr_ops = {
98 * { RTM_NEWADDR, NL_ACT_NEW, "new" },
99 * { RTM_DELADDR, NL_ACT_DEL, "del" },
100 * { RTM_GETADDR, NL_ACT_GET, "get" },
101 * END_OF_MSGTYPES_LIST,
103 * .co_groups = addr_groups,
106 * // It is now possible to keep the cache up-to-date using the cache manager.
121 #define NL_ACT_MAX (__NL_ACT_MAX - 1)
123 #define END_OF_MSGTYPES_LIST { -1, -1, NULL }
126 * Message type to cache action association
130 /** Netlink message type */
133 /** Cache action to take */
136 /** Name of operation for human-readable printing */
141 * Address family to netlink group association
145 /** Address family */
148 /** Netlink group identifier */
152 #define END_OF_GROUP_LIST AF_UNSPEC, 0
154 struct nl_parser_param
156 int (*pp_cb)(struct nl_object *, struct nl_parser_param *);
169 struct nl_af_group * co_groups;
172 * Called whenever an update of the cache is required. Must send
173 * a request message to the kernel requesting a complete dump.
175 int (*co_request_update)(struct nl_cache *, struct nl_sock *);
178 * Called whenever a message was received that needs to be parsed.
179 * Must parse the message and call the paser callback function
180 * (nl_parser_param) provided via the argument.
182 int (*co_msg_parser)(struct nl_cache_ops *, struct sockaddr_nl *,
183 struct nlmsghdr *, struct nl_parser_param *);
185 struct nl_object_ops * co_obj_ops;
187 struct nl_cache_ops *co_next;
188 struct nl_cache *co_major_cache;
189 struct genl_ops * co_genl;
190 struct nl_msgtype co_msgtypes[];