package/libnl-tiny/src/include/netlink/cache-api.h

   1 /*
   2  * netlink/cache-api.h          Caching API
   3  *
   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
   7  *      of the License.
   8  *
   9  * Copyright (c) 2003-2006 Thomas Graf <tgraf@suug.ch>
  10  */
  11
  12 #ifndef NETLINK_CACHE_API_H_
  13 #define NETLINK_CACHE_API_H_
  14
  15 #include <netlink/netlink.h>
  16
  17 #ifdef __cplusplus
  18 extern "C" {
  19 #endif
  20
  21 /**
  22  * @ingroup cache
  23  * @defgroup cache_api Cache Implementation
  24  * @brief
  25  *
  26  * @par 1) Cache Definition
  27  * @code
  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,
  33  * };
  34  * @endcode
  35  *
  36  * @par 2)
  37  * @code
  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)
  43  * {
  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);
  46  * }
  47  *
  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)
  55  * {
  56  *      struct my_obj *obj;
  57  *
  58  *      obj = my_obj_alloc();
  59  *      obj->ce_msgtype = nlh->nlmsg_type;
  60  *
  61  *      // Parse the netlink message and continue creating the object.
  62  *
  63  *      err = pp->pp_cb((struct nl_object *) obj, pp);
  64  *      if (err < 0)
  65  *              goto errout;
  66  * }
  67  *
  68  * struct nl_cache_ops my_cache_ops = {
  69  *      ...
  70  *      .co_request_update      = my_request_update,
  71  *      .co_msg_parser          = my_msg_parser,
  72  * };
  73  * @endcode
  74  *
  75  * @par 3) Notification based Updates
  76  * @code
  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.
  79  * //
  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 },
  89  * };
  90  *
  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 = {
  96  *      ...
  97  *      .co_msgtypes            = {
  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,
 102  *                              },
 103  *      .co_groups              = addr_groups,
 104  * };
 105  *
 106  * // It is now possible to keep the cache up-to-date using the cache manager.
 107  * @endcode
 108  * @{
 109  */
 110
 111 enum {
 112         NL_ACT_UNSPEC,
 113         NL_ACT_NEW,
 114         NL_ACT_DEL,
 115         NL_ACT_GET,
 116         NL_ACT_SET,
 117         NL_ACT_CHANGE,
 118         __NL_ACT_MAX,
 119 };
 120
 121 #define NL_ACT_MAX (__NL_ACT_MAX - 1)
 122
 123 #define END_OF_MSGTYPES_LIST    { -1, -1, NULL }
 124
 125 /**
 126  * Message type to cache action association
 127  */
 128 struct nl_msgtype
 129 {
 130         /** Netlink message type */
 131         int                     mt_id;
 132
 133         /** Cache action to take */
 134         int                     mt_act;
 135
 136         /** Name of operation for human-readable printing */
 137         char *                  mt_name;
 138 };
 139
 140 /**
 141  * Address family to netlink group association
 142  */
 143 struct nl_af_group
 144 {
 145         /** Address family */
 146         int                     ag_family;
 147
 148         /** Netlink group identifier */
 149         int                     ag_group;
 150 };
 151
 152 #define END_OF_GROUP_LIST AF_UNSPEC, 0
 153
 154 struct nl_parser_param
 155 {
 156         int             (*pp_cb)(struct nl_object *, struct nl_parser_param *);
 157         void *            pp_arg;
 158 };
 159
 160 /**
 161  * Cache Operations
 162  */
 163 struct nl_cache_ops
 164 {
 165         char  *                 co_name;
 166
 167         int                     co_hdrsize;
 168         int                     co_protocol;
 169         struct nl_af_group *    co_groups;
 170
 171         /**
 172          * Called whenever an update of the cache is required. Must send
 173          * a request message to the kernel requesting a complete dump.
 174          */
 175         int   (*co_request_update)(struct nl_cache *, struct nl_sock *);
 176
 177         /**
 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.
 181          */
 182         int   (*co_msg_parser)(struct nl_cache_ops *, struct sockaddr_nl *,
 183                                struct nlmsghdr *, struct nl_parser_param *);
 184
 185         struct nl_object_ops *  co_obj_ops;
 186
 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[];
 191 };
 192
 193 /** @} */
 194
 195 #ifdef __cplusplus
 196 }
 197 #endif
 198
 199 #endif