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+/*
+ * netlink/cache-api.h Caching API
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation version 2.1
+ * of the License.
+ *
+ * Copyright (c) 2003-2006 Thomas Graf <tgraf@suug.ch>
+ */
+
+#ifndef NETLINK_CACHE_API_H_
+#define NETLINK_CACHE_API_H_
+
+#include <netlink/netlink.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @ingroup cache
+ * @defgroup cache_api Cache Implementation
+ * @brief
+ *
+ * @par 1) Cache Definition
+ * @code
+ * struct nl_cache_ops my_cache_ops = {
+ * .co_name = "route/link",
+ * .co_protocol = NETLINK_ROUTE,
+ * .co_hdrsize = sizeof(struct ifinfomsg),
+ * .co_obj_ops = &my_obj_ops,
+ * };
+ * @endcode
+ *
+ * @par 2)
+ * @code
+ * // The simplest way to fill a cache is by providing a request-update
+ * // function which must trigger a complete dump on the kernel-side of
+ * // whatever the cache covers.
+ * static int my_request_update(struct nl_cache *cache,
+ * struct nl_sock *socket)
+ * {
+ * // In this example, we request a full dump of the interface table
+ * return nl_rtgen_request(socket, RTM_GETLINK, AF_UNSPEC, NLM_F_DUMP);
+ * }
+ *
+ * // The resulting netlink messages sent back will be fed into a message
+ * // parser one at a time. The message parser has to extract all relevant
+ * // information from the message and create an object reflecting the
+ * // contents of the message and pass it on to the parser callback function
+ * // provide which will add the object to the cache.
+ * static int my_msg_parser(struct nl_cache_ops *ops, struct sockaddr_nl *who,
+ * struct nlmsghdr *nlh, struct nl_parser_param *pp)
+ * {
+ * struct my_obj *obj;
+ *
+ * obj = my_obj_alloc();
+ * obj->ce_msgtype = nlh->nlmsg_type;
+ *
+ * // Parse the netlink message and continue creating the object.
+ *
+ * err = pp->pp_cb((struct nl_object *) obj, pp);
+ * if (err < 0)
+ * goto errout;
+ * }
+ *
+ * struct nl_cache_ops my_cache_ops = {
+ * ...
+ * .co_request_update = my_request_update,
+ * .co_msg_parser = my_msg_parser,
+ * };
+ * @endcode
+ *
+ * @par 3) Notification based Updates
+ * @code
+ * // Caches can be kept up-to-date based on notifications if the kernel
+ * // sends out notifications whenever an object is added/removed/changed.
+ * //
+ * // It is trivial to support this, first a list of groups needs to be
+ * // defined which are required to join in order to receive all necessary
+ * // notifications. The groups are separated by address family to support
+ * // the common situation where a separate group is used for each address
+ * // family. If there is only one group, simply specify AF_UNSPEC.
+ * static struct nl_af_group addr_groups[] = {
+ * { AF_INET, RTNLGRP_IPV4_IFADDR },
+ * { AF_INET6, RTNLGRP_IPV6_IFADDR },
+ * { END_OF_GROUP_LIST },
+ * };
+ *
+ * // In order for the caching system to know the meaning of each message
+ * // type it requires a table which maps each supported message type to
+ * // a cache action, e.g. RTM_NEWADDR means address has been added or
+ * // updated, RTM_DELADDR means address has been removed.
+ * static struct nl_cache_ops rtnl_addr_ops = {
+ * ...
+ * .co_msgtypes = {
+ * { RTM_NEWADDR, NL_ACT_NEW, "new" },
+ * { RTM_DELADDR, NL_ACT_DEL, "del" },
+ * { RTM_GETADDR, NL_ACT_GET, "get" },
+ * END_OF_MSGTYPES_LIST,
+ * },
+ * .co_groups = addr_groups,
+ * };
+ *
+ * // It is now possible to keep the cache up-to-date using the cache manager.
+ * @endcode
+ * @{
+ */
+
+enum {
+ NL_ACT_UNSPEC,
+ NL_ACT_NEW,
+ NL_ACT_DEL,
+ NL_ACT_GET,
+ NL_ACT_SET,
+ NL_ACT_CHANGE,
+ __NL_ACT_MAX,
+};
+
+#define NL_ACT_MAX (__NL_ACT_MAX - 1)
+
+#define END_OF_MSGTYPES_LIST { -1, -1, NULL }
+
+/**
+ * Message type to cache action association
+ */
+struct nl_msgtype
+{
+ /** Netlink message type */
+ int mt_id;
+
+ /** Cache action to take */
+ int mt_act;
+
+ /** Name of operation for human-readable printing */
+ char * mt_name;
+};
+
+/**
+ * Address family to netlink group association
+ */
+struct nl_af_group
+{
+ /** Address family */
+ int ag_family;
+
+ /** Netlink group identifier */
+ int ag_group;
+};
+
+#define END_OF_GROUP_LIST AF_UNSPEC, 0
+
+struct nl_parser_param
+{
+ int (*pp_cb)(struct nl_object *, struct nl_parser_param *);
+ void * pp_arg;
+};
+
+/**
+ * Cache Operations
+ */
+struct nl_cache_ops
+{
+ char * co_name;
+
+ int co_hdrsize;
+ int co_protocol;
+ struct nl_af_group * co_groups;
+
+ /**
+ * Called whenever an update of the cache is required. Must send
+ * a request message to the kernel requesting a complete dump.
+ */
+ int (*co_request_update)(struct nl_cache *, struct nl_sock *);
+
+ /**
+ * Called whenever a message was received that needs to be parsed.
+ * Must parse the message and call the paser callback function
+ * (nl_parser_param) provided via the argument.
+ */
+ int (*co_msg_parser)(struct nl_cache_ops *, struct sockaddr_nl *,
+ struct nlmsghdr *, struct nl_parser_param *);
+
+ struct nl_object_ops * co_obj_ops;
+
+ struct nl_cache_ops *co_next;
+ struct nl_cache *co_major_cache;
+ struct genl_ops * co_genl;
+ struct nl_msgtype co_msgtypes[];
+};
+
+/** @} */
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif