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1 office 1 /*
2 * lib/genl/mngt.c Generic Netlink Management
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) 2003-2008 Thomas Graf <tgraf@suug.ch>
10 */
11  
12 /**
13 * @ingroup genl
14 * @defgroup genl_mngt Management
15 *
16 * @par 1) Registering a generic netlink module
17 * @code
18 * #include <netlink/genl/mngt.h>
19 *
20 * // First step is to define all the commands being used in
21 * // particular generic netlink family. The ID and name are
22 * // mandatory to be filled out. A callback function and
23 * // most the attribute policy that comes with it must be
24 * // defined for commands expected to be issued towards
25 * // userspace.
26 * static struct genl_cmd foo_cmds[] = {
27 * {
28 * .c_id = FOO_CMD_NEW,
29 * .c_name = "NEWFOO" ,
30 * .c_maxattr = FOO_ATTR_MAX,
31 * .c_attr_policy = foo_policy,
32 * .c_msg_parser = foo_msg_parser,
33 * },
34 * {
35 * .c_id = FOO_CMD_DEL,
36 * .c_name = "DELFOO" ,
37 * },
38 * };
39 *
40 * // The list of commands must then be integrated into a
41 * // struct genl_ops serving as handle for this particular
42 * // family.
43 * static struct genl_ops my_genl_ops = {
44 * .o_cmds = foo_cmds,
45 * .o_ncmds = ARRAY_SIZE(foo_cmds),
46 * };
47 *
48 * // Using the above struct genl_ops an arbitary number of
49 * // cache handles can be associated to it.
50 * //
51 * // The macro GENL_HDRSIZE() must be used to specify the
52 * // length of the header to automatically take headers on
53 * // generic layers into account.
54 * //
55 * // The macro GENL_FAMILY() is used to represent the generic
56 * // netlink family id.
57 * static struct nl_cache_ops genl_foo_ops = {
58 * .co_name = "genl/foo",
59 * .co_hdrsize = GENL_HDRSIZE(sizeof(struct my_hdr)),
60 * .co_msgtypes = GENL_FAMILY(GENL_ID_GENERATE, "foo"),
61 * .co_genl = &my_genl_ops,
62 * .co_protocol = NETLINK_GENERIC,
63 * .co_request_update = foo_request_update,
64 * .co_obj_ops = &genl_foo_ops,
65 * };
66 *
67 * // Finally each cache handle for a generic netlink family
68 * // must be registered using genl_register().
69 * static void __init foo_init(void)
70 * {
71 * genl_register(&genl_foo_ops);
72 * }
73 *
74 * // ... respectively unregsted again.
75 * static void __exit foo_exit(void)
76 * {
77 * genl_unregister(&genl_foo_ops);
78 * }
79 * @endcode
80 * @{
81 */
82  
83 #include <netlink-generic.h>
84 #include <netlink/netlink.h>
85 #include <netlink/genl/genl.h>
86 #include <netlink/genl/mngt.h>
87 #include <netlink/genl/family.h>
88 #include <netlink/genl/ctrl.h>
89 #include <netlink/utils.h>
90  
91 static NL_LIST_HEAD(genl_ops_list);
92  
93 static int genl_msg_parser(struct nl_cache_ops *ops, struct sockaddr_nl *who,
94 struct nlmsghdr *nlh, struct nl_parser_param *pp)
95 {
96 int i, err;
97 struct genlmsghdr *ghdr;
98 struct genl_cmd *cmd;
99  
100 ghdr = nlmsg_data(nlh);
101  
102 if (ops->co_genl == NULL)
103 BUG();
104  
105 for (i = 0; i < ops->co_genl->o_ncmds; i++) {
106 cmd = &ops->co_genl->o_cmds[i];
107 if (cmd->c_id == ghdr->cmd)
108 goto found;
109 }
110  
111 err = -NLE_MSGTYPE_NOSUPPORT;
112 goto errout;
113  
114 found:
115 if (cmd->c_msg_parser == NULL)
116 err = -NLE_OPNOTSUPP;
117 else {
118 struct nlattr *tb[cmd->c_maxattr + 1];
119 struct genl_info info = {
120 .who = who,
121 .nlh = nlh,
122 .genlhdr = ghdr,
123 .userhdr = genlmsg_data(ghdr),
124 .attrs = tb,
125 };
126  
127 err = nlmsg_parse(nlh, ops->co_hdrsize, tb, cmd->c_maxattr,
128 cmd->c_attr_policy);
129 if (err < 0)
130 goto errout;
131  
132 err = cmd->c_msg_parser(ops, cmd, &info, pp);
133 }
134 errout:
135 return err;
136  
137 }
138  
139 /**
140 * @name Register/Unregister
141 * @{
142 */
143  
144 /**
145 * Register generic netlink operations
146 * @arg ops cache operations
147 */
148 int genl_register(struct nl_cache_ops *ops)
149 {
150 int err;
151  
152 if (ops->co_protocol != NETLINK_GENERIC) {
153 err = -NLE_PROTO_MISMATCH;
154 goto errout;
155 }
156  
157 if (ops->co_hdrsize < GENL_HDRSIZE(0)) {
158 err = -NLE_INVAL;
159 goto errout;
160 }
161  
162 if (ops->co_genl == NULL) {
163 err = -NLE_INVAL;
164 goto errout;
165 }
166  
167 ops->co_genl->o_cache_ops = ops;
168 ops->co_genl->o_name = ops->co_msgtypes[0].mt_name;
169 ops->co_genl->o_family = ops->co_msgtypes[0].mt_id;
170 ops->co_msg_parser = genl_msg_parser;
171  
172 /* FIXME: check for dup */
173  
174 nl_list_add_tail(&ops->co_genl->o_list, &genl_ops_list);
175  
176 err = nl_cache_mngt_register(ops);
177 errout:
178 return err;
179 }
180  
181 /**
182 * Unregister generic netlink operations
183 * @arg ops cache operations
184 */
185 void genl_unregister(struct nl_cache_ops *ops)
186 {
187 nl_cache_mngt_unregister(ops);
188 nl_list_del(&ops->co_genl->o_list);
189 }
190  
191 /** @} */
192  
193 /** @} */