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, const struct nla_policy *); 68 extern int nlmsg_validate(const struct nlmsghdr *, int, int, 69 const 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 309
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