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1 office 1 /*
2 * netlink/msg.c Netlink Messages Interface
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_MSG_H_
13 #define NETLINK_MSG_H_
14  
15 #include <netlink/netlink.h>
16 #include <netlink/object.h>
17  
18 #ifdef __cplusplus
19 extern "C" {
20 #endif
21  
22 struct nla_policy;
23  
24 #define NL_DONTPAD 0
25  
26 /**
27 * @ingroup msg
28 * @brief
29 * Will cause the netlink pid to be set to the pid assigned to
30 * the netlink handle (socket) just before sending the message off.
31 * @note Requires the use of nl_send_auto_complete()!
32 */
33 #define NL_AUTO_PID 0
34  
35 /**
36 * @ingroup msg
37 * @brief
38 * May be used to refer to a sequence number which should be
39 * automatically set just before sending the message off.
40 * @note Requires the use of nl_send_auto_complete()!
41 */
42 #define NL_AUTO_SEQ 0
43  
44 #define NL_MSG_CRED_PRESENT 1
45  
46 struct nl_msg
47 {
48 int nm_protocol;
49 int nm_flags;
50 struct sockaddr_nl nm_src;
51 struct sockaddr_nl nm_dst;
52 struct ucred nm_creds;
53 struct nlmsghdr * nm_nlh;
54 size_t nm_size;
55 int nm_refcnt;
56 };
57  
58  
59 struct nl_msg;
60 struct nl_tree;
61 struct ucred;
62  
63 /* message parsing */
64 extern int nlmsg_ok(const struct nlmsghdr *, int);
65 extern struct nlmsghdr * nlmsg_next(struct nlmsghdr *, int *);
66 extern int nlmsg_parse(struct nlmsghdr *, int, struct nlattr **,
67 int, struct nla_policy *);
68 extern int nlmsg_validate(struct nlmsghdr *, int, int,
69 struct nla_policy *);
70  
71 extern struct nl_msg * nlmsg_alloc(void);
72 extern struct nl_msg * nlmsg_alloc_size(size_t);
73 extern struct nl_msg * nlmsg_alloc_simple(int, int);
74 extern void nlmsg_set_default_size(size_t);
75 extern struct nl_msg * nlmsg_inherit(struct nlmsghdr *);
76 extern struct nl_msg * nlmsg_convert(struct nlmsghdr *);
77 extern void * nlmsg_reserve(struct nl_msg *, size_t, int);
78 extern int nlmsg_append(struct nl_msg *, void *, size_t, int);
79  
80 extern struct nlmsghdr * nlmsg_put(struct nl_msg *, uint32_t, uint32_t,
81 int, int, int);
82 extern void nlmsg_free(struct nl_msg *);
83  
84 extern int nl_msg_parse(struct nl_msg *,
85 void (*cb)(struct nl_object *, void *),
86 void *);
87  
88 extern void nl_msg_dump(struct nl_msg *, FILE *);
89  
90 /**
91 * length of netlink message not including padding
92 * @arg payload length of message payload
93 */
94 static inline int nlmsg_msg_size(int payload)
95 {
96 return NLMSG_HDRLEN + payload;
97 }
98  
99 /**
100 * length of netlink message including padding
101 * @arg payload length of message payload
102 */
103 static inline int nlmsg_total_size(int payload)
104 {
105 return NLMSG_ALIGN(nlmsg_msg_size(payload));
106 }
107  
108 /**
109 * length of padding at the message's tail
110 * @arg payload length of message payload
111 */
112 static inline int nlmsg_padlen(int payload)
113 {
114 return nlmsg_total_size(payload) - nlmsg_msg_size(payload);
115 }
116  
117 /**
118 * head of message payload
119 * @arg nlh netlink messsage header
120 */
121 static inline void *nlmsg_data(const struct nlmsghdr *nlh)
122 {
123 return (unsigned char *) nlh + NLMSG_HDRLEN;
124 }
125  
126 static inline void *nlmsg_tail(const struct nlmsghdr *nlh)
127 {
128 return (unsigned char *) nlh + NLMSG_ALIGN(nlh->nlmsg_len);
129 }
130  
131 /**
132 * length of message payload
133 * @arg nlh netlink message header
134 */
135 static inline int nlmsg_len(const struct nlmsghdr *nlh)
136 {
137 return nlh->nlmsg_len - NLMSG_HDRLEN;
138 }
139  
140 /**
141 * head of attributes data
142 * @arg nlh netlink message header
143 * @arg hdrlen length of family specific header
144 */
145 static inline struct nlattr *nlmsg_attrdata(const struct nlmsghdr *nlh, int hdrlen)
146 {
147 unsigned char *data = (unsigned char*)nlmsg_data(nlh);
148 return (struct nlattr *) (data + NLMSG_ALIGN(hdrlen));
149 }
150  
151 /**
152 * length of attributes data
153 * @arg nlh netlink message header
154 * @arg hdrlen length of family specific header
155 */
156 static inline int nlmsg_attrlen(const struct nlmsghdr *nlh, int hdrlen)
157 {
158 return nlmsg_len(nlh) - NLMSG_ALIGN(hdrlen);
159 }
160  
161 static inline int nlmsg_valid_hdr(const struct nlmsghdr *nlh, int hdrlen)
162 {
163 if (nlh->nlmsg_len < (uint)nlmsg_msg_size(hdrlen))
164 return 0;
165  
166 return 1;
167 }
168  
169  
170 static inline void nlmsg_set_proto(struct nl_msg *msg, int protocol)
171 {
172 msg->nm_protocol = protocol;
173 }
174  
175 static inline int nlmsg_get_proto(struct nl_msg *msg)
176 {
177 return msg->nm_protocol;
178 }
179  
180 static inline size_t nlmsg_get_max_size(struct nl_msg *msg)
181 {
182 return msg->nm_size;
183 }
184  
185 static inline void nlmsg_set_src(struct nl_msg *msg, struct sockaddr_nl *addr)
186 {
187 memcpy(&msg->nm_src, addr, sizeof(*addr));
188 }
189  
190 static inline struct sockaddr_nl *nlmsg_get_src(struct nl_msg *msg)
191 {
192 return &msg->nm_src;
193 }
194  
195 static inline void nlmsg_set_dst(struct nl_msg *msg, struct sockaddr_nl *addr)
196 {
197 memcpy(&msg->nm_dst, addr, sizeof(*addr));
198 }
199  
200 static inline struct sockaddr_nl *nlmsg_get_dst(struct nl_msg *msg)
201 {
202 return &msg->nm_dst;
203 }
204  
205 static inline void nlmsg_set_creds(struct nl_msg *msg, struct ucred *creds)
206 {
207 memcpy(&msg->nm_creds, creds, sizeof(*creds));
208 msg->nm_flags |= NL_MSG_CRED_PRESENT;
209 }
210  
211 static inline struct ucred *nlmsg_get_creds(struct nl_msg *msg)
212 {
213 if (msg->nm_flags & NL_MSG_CRED_PRESENT)
214 return &msg->nm_creds;
215 return NULL;
216 }
217  
218 /**
219 * Return actual netlink message
220 * @arg n netlink message
221 *
222 * Returns the actual netlink message casted to the type of the netlink
223 * message header.
224 *
225 * @return A pointer to the netlink message.
226 */
227 static inline struct nlmsghdr *nlmsg_hdr(struct nl_msg *n)
228 {
229 return n->nm_nlh;
230 }
231  
232 /**
233 * Acquire a reference on a netlink message
234 * @arg msg message to acquire reference from
235 */
236 static inline void nlmsg_get(struct nl_msg *msg)
237 {
238 msg->nm_refcnt++;
239 }
240  
241 /**
242 * Expand maximum payload size of a netlink message
243 * @arg n Netlink message.
244 * @arg newlen New maximum payload size.
245 *
246 * Reallocates the payload section of a netlink message and increases
247 * the maximum payload size of the message.
248 *
249 * @note Any pointers pointing to old payload block will be stale and
250 * need to be refetched. Therfore, do not expand while constructing
251 * nested attributes or while reserved data blocks are held.
252 *
253 * @return 0 on success or a negative error code.
254 */
255 static inline int nlmsg_expand(struct nl_msg *n, size_t newlen)
256 {
257 void *tmp;
258  
259 if (newlen <= n->nm_size)
260 return -NLE_INVAL;
261  
262 tmp = realloc(n->nm_nlh, newlen);
263 if (tmp == NULL)
264 return -NLE_NOMEM;
265  
266 n->nm_nlh = (struct nlmsghdr*)tmp;
267 n->nm_size = newlen;
268  
269 return 0;
270 }
271  
272  
273 /**
274 * @name Iterators
275 * @{
276 */
277  
278 /**
279 * @ingroup msg
280 * Iterate over a stream of attributes in a message
281 * @arg pos loop counter, set to current attribute
282 * @arg nlh netlink message header
283 * @arg hdrlen length of family header
284 * @arg rem initialized to len, holds bytes currently remaining in stream
285 */
286 #define nlmsg_for_each_attr(pos, nlh, hdrlen, rem) \
287 nla_for_each_attr(pos, nlmsg_attrdata(nlh, hdrlen), \
288 nlmsg_attrlen(nlh, hdrlen), rem)
289  
290 /**
291 * Iterate over a stream of messages
292 * @arg pos loop counter, set to current message
293 * @arg head head of message stream
294 * @arg len length of message stream
295 * @arg rem initialized to len, holds bytes currently remaining in stream
296 */
297 #define nlmsg_for_each_msg(pos, head, len, rem) \
298 for (pos = head, rem = len; \
299 nlmsg_ok(pos, rem); \
300 pos = nlmsg_next(pos, &(rem)))
301  
302 /** @} */
303  
304 #ifdef __cplusplus
305 }
306 #endif
307  
308 #endif