| 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 |
| 200 | |
