/* * lib/cache.c Caching Module * * 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) 2003-2008 Thomas Graf */ /** * @ingroup cache_mngt * @defgroup cache Cache * * @code * Cache Management | | Type Specific Cache Operations * * | | +----------------+ +------------+ * | request update | | msg_parser | * | | +----------------+ +------------+ * +- - - - -^- - - - - - - -^- -|- - - - * nl_cache_update: | | | | * 1) --------- co_request_update ------+ | | * | | | * 2) destroy old cache +----------- pp_cb ---------|---+ * | | | * 3) ---------- nl_recvmsgs ----------+ +- cb_valid -+ * +--------------+ | | | | * | nl_cache_add |<-----+ + - - -v- -|- - - - - - - - - - - * +--------------+ | | +-------------+ * | nl_recvmsgs | * | | +-----|-^-----+ * +---v-|---+ * | | | nl_recv | * +---------+ * | | Core Netlink * @endcode * * @{ */ #include #include #include #include #include /** * @name Cache Creation/Deletion * @{ */ /** * Allocate an empty cache * @arg ops cache operations to base the cache on * * @return A newly allocated and initialized cache. */ struct nl_cache *nl_cache_alloc(struct nl_cache_ops *ops) { struct nl_cache *cache; cache = calloc(1, sizeof(*cache)); if (!cache) return NULL; nl_init_list_head(&cache->c_items); cache->c_ops = ops; NL_DBG(2, "Allocated cache %p <%s>.\n", cache, nl_cache_name(cache)); return cache; } int nl_cache_alloc_and_fill(struct nl_cache_ops *ops, struct nl_sock *sock, struct nl_cache **result) { struct nl_cache *cache; int err; if (!(cache = nl_cache_alloc(ops))) return -NLE_NOMEM; if (sock && (err = nl_cache_refill(sock, cache)) < 0) { nl_cache_free(cache); return err; } *result = cache; return 0; } /** * Clear a cache. * @arg cache cache to clear * * Removes all elements of a cache. */ void nl_cache_clear(struct nl_cache *cache) { struct nl_object *obj, *tmp; NL_DBG(1, "Clearing cache %p <%s>...\n", cache, nl_cache_name(cache)); nl_list_for_each_entry_safe(obj, tmp, &cache->c_items, ce_list) nl_cache_remove(obj); } /** * Free a cache. * @arg cache Cache to free. * * Removes all elements of a cache and frees all memory. * * @note Use this function if you are working with allocated caches. */ void nl_cache_free(struct nl_cache *cache) { if (!cache) return; nl_cache_clear(cache); NL_DBG(1, "Freeing cache %p <%s>...\n", cache, nl_cache_name(cache)); free(cache); } /** @} */ /** * @name Cache Modifications * @{ */ static int __cache_add(struct nl_cache *cache, struct nl_object *obj) { obj->ce_cache = cache; nl_list_add_tail(&obj->ce_list, &cache->c_items); cache->c_nitems++; NL_DBG(1, "Added %p to cache %p <%s>.\n", obj, cache, nl_cache_name(cache)); return 0; } /** * Add object to a cache. * @arg cache Cache to add object to * @arg obj Object to be added to the cache * * Adds the given object to the specified cache. The object is cloned * if it has been added to another cache already. * * @return 0 or a negative error code. */ int nl_cache_add(struct nl_cache *cache, struct nl_object *obj) { struct nl_object *new; if (cache->c_ops->co_obj_ops != obj->ce_ops) return -NLE_OBJ_MISMATCH; if (!nl_list_empty(&obj->ce_list)) { new = nl_object_clone(obj); if (!new) return -NLE_NOMEM; } else { nl_object_get(obj); new = obj; } return __cache_add(cache, new); } /** * Removes an object from a cache. * @arg obj Object to remove from its cache * * Removes the object \c obj from the cache it is assigned to, since * an object can only be assigned to one cache at a time, the cache * must ne be passed along with it. */ void nl_cache_remove(struct nl_object *obj) { struct nl_cache *cache = obj->ce_cache; if (cache == NULL) return; nl_list_del(&obj->ce_list); obj->ce_cache = NULL; nl_object_put(obj); cache->c_nitems--; NL_DBG(1, "Deleted %p from cache %p <%s>.\n", obj, cache, nl_cache_name(cache)); } /** @} */ /** * @name Synchronization * @{ */ /** * Request a full dump from the kernel to fill a cache * @arg sk Netlink socket. * @arg cache Cache subjected to be filled. * * Send a dumping request to the kernel causing it to dump all objects * related to the specified cache to the netlink socket. * * Use nl_cache_pickup() to read the objects from the socket and fill them * into a cache. */ int nl_cache_request_full_dump(struct nl_sock *sk, struct nl_cache *cache) { NL_DBG(2, "Requesting dump from kernel for cache %p <%s>...\n", cache, nl_cache_name(cache)); if (cache->c_ops->co_request_update == NULL) return -NLE_OPNOTSUPP; return cache->c_ops->co_request_update(cache, sk); } /** @cond SKIP */ struct update_xdata { struct nl_cache_ops *ops; struct nl_parser_param *params; }; static int update_msg_parser(struct nl_msg *msg, void *arg) { struct update_xdata *x = arg; return nl_cache_parse(x->ops, &msg->nm_src, msg->nm_nlh, x->params); } /** @endcond */ int __cache_pickup(struct nl_sock *sk, struct nl_cache *cache, struct nl_parser_param *param) { int err; struct nl_cb *cb; struct update_xdata x = { .ops = cache->c_ops, .params = param, }; NL_DBG(1, "Picking up answer for cache %p <%s>...\n", cache, nl_cache_name(cache)); cb = nl_cb_clone(sk->s_cb); if (cb == NULL) return -NLE_NOMEM; nl_cb_set(cb, NL_CB_VALID, NL_CB_CUSTOM, update_msg_parser, &x); err = nl_recvmsgs(sk, cb); if (err < 0) NL_DBG(2, "While picking up for %p <%s>, recvmsgs() returned " \ "%d: %s", cache, nl_cache_name(cache), err, nl_geterror(err)); nl_cb_put(cb); return err; } static int pickup_cb(struct nl_object *c, struct nl_parser_param *p) { return nl_cache_add((struct nl_cache *) p->pp_arg, c); } /** * Pickup a netlink dump response and put it into a cache. * @arg sk Netlink socket. * @arg cache Cache to put items into. * * Waits for netlink messages to arrive, parses them and puts them into * the specified cache. * * @return 0 on success or a negative error code. */ int nl_cache_pickup(struct nl_sock *sk, struct nl_cache *cache) { struct nl_parser_param p = { .pp_cb = pickup_cb, .pp_arg = cache, }; return __cache_pickup(sk, cache, &p); } /** @} */ /** * @name Parsing * @{ */ /** @cond SKIP */ int nl_cache_parse(struct nl_cache_ops *ops, struct sockaddr_nl *who, struct nlmsghdr *nlh, struct nl_parser_param *params) { int i, err; if (!nlmsg_valid_hdr(nlh, ops->co_hdrsize)) return -NLE_MSG_TOOSHORT; for (i = 0; ops->co_msgtypes[i].mt_id >= 0; i++) { if (ops->co_msgtypes[i].mt_id == nlh->nlmsg_type) { err = ops->co_msg_parser(ops, who, nlh, params); if (err != -NLE_OPNOTSUPP) goto errout; } } err = -NLE_MSGTYPE_NOSUPPORT; errout: return err; } /** @endcond */ /** * Parse a netlink message and add it to the cache. * @arg cache cache to add element to * @arg msg netlink message * * Parses a netlink message by calling the cache specific message parser * and adds the new element to the cache. * * @return 0 or a negative error code. */ int nl_cache_parse_and_add(struct nl_cache *cache, struct nl_msg *msg) { struct nl_parser_param p = { .pp_cb = pickup_cb, .pp_arg = cache, }; return nl_cache_parse(cache->c_ops, NULL, nlmsg_hdr(msg), &p); } /** * (Re)fill a cache with the contents in the kernel. * @arg sk Netlink socket. * @arg cache cache to update * * Clears the specified cache and fills it with the current state in * the kernel. * * @return 0 or a negative error code. */ int nl_cache_refill(struct nl_sock *sk, struct nl_cache *cache) { int err; err = nl_cache_request_full_dump(sk, cache); if (err < 0) return err; NL_DBG(2, "Upading cache %p <%s>, request sent, waiting for dump...\n", cache, nl_cache_name(cache)); nl_cache_clear(cache); return nl_cache_pickup(sk, cache); } /** @} */