libnl 2.0

/tmp/buildd/libnl2-2.0/lib/msg.c

00001 /*
00002  * lib/msg.c            Netlink Messages Interface
00003  *
00004  *      This library is free software; you can redistribute it and/or
00005  *      modify it under the terms of the GNU Lesser General Public
00006  *      License as published by the Free Software Foundation version 2.1
00007  *      of the License.
00008  *
00009  * Copyright (c) 2003-2008 Thomas Graf <tgraf@suug.ch>
00010  */
00011 
00012 /**
00013  * @ingroup core
00014  * @defgroup msg Messages
00015  * Netlink Message Construction/Parsing Interface
00016  * 
00017  * The following information is partly extracted from RFC3549
00018  * (ftp://ftp.rfc-editor.org/in-notes/rfc3549.txt)
00019  *
00020  * @par Message Format
00021  * Netlink messages consist of a byte stream with one or multiple
00022  * Netlink headers and an associated payload.  If the payload is too big
00023  * to fit into a single message it, can be split over multiple Netlink
00024  * messages, collectively called a multipart message.  For multipart
00025  * messages, the first and all following headers have the \c NLM_F_MULTI
00026  * Netlink header flag set, except for the last header which has the
00027  * Netlink header type \c NLMSG_DONE.
00028  *
00029  * @par
00030  * The Netlink message header (\link nlmsghdr struct nlmsghdr\endlink) is shown below.
00031  * @code   
00032  * 0                   1                   2                   3
00033  * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
00034  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
00035  * |                          Length                             |
00036  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
00037  * |            Type              |           Flags              |
00038  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
00039  * |                      Sequence Number                        |
00040  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
00041  * |                      Process ID (PID)                       |
00042  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
00043  * @endcode
00044  *
00045  * @par
00046  * The netlink message header and payload must be aligned properly:
00047  * @code
00048  *  <------- NLMSG_ALIGN(hlen) ------> <---- NLMSG_ALIGN(len) --->
00049  * +----------------------------+- - -+- - - - - - - - - - -+- - -+
00050  * |           Header           | Pad |       Payload       | Pad |
00051  * |      struct nlmsghdr       |     |                     |     |
00052  * +----------------------------+- - -+- - - - - - - - - - -+- - -+
00053  * @endcode
00054  * @par
00055  * Message Format:
00056  * @code
00057  *    <--- nlmsg_total_size(payload)  --->
00058  *    <-- nlmsg_msg_size(payload) ->
00059  *   +----------+- - -+-------------+- - -+-------- - -
00060  *   | nlmsghdr | Pad |   Payload   | Pad | nlmsghdr
00061  *   +----------+- - -+-------------+- - -+-------- - -
00062  *   nlmsg_data(nlh)---^                   ^
00063  *   nlmsg_next(nlh)-----------------------+
00064  * @endcode
00065  * @par
00066  * The payload may consist of arbitary data but may have strict
00067  * alignment and formatting rules depening on the specific netlink
00068  * families.
00069  * @par
00070  * @code
00071  *    <---------------------- nlmsg_len(nlh) --------------------->
00072  *    <------ hdrlen ------>       <- nlmsg_attrlen(nlh, hdrlen) ->
00073  *   +----------------------+- - -+--------------------------------+
00074  *   |     Family Header    | Pad |           Attributes           |
00075  *   +----------------------+- - -+--------------------------------+
00076  *   nlmsg_attrdata(nlh, hdrlen)---^
00077  * @endcode
00078  * @par The ACK Netlink Message
00079  * This message is actually used to denote both an ACK and a NACK.
00080  * Typically, the direction is from FEC to CPC (in response to an ACK
00081  * request message).  However, the CPC should be able to send ACKs back
00082  * to FEC when requested.
00083  * @code
00084  *  0                   1                   2                   3
00085  *  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
00086  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
00087  * |                       Netlink message header                  |
00088  * |                       type = NLMSG_ERROR                      |
00089  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
00090  * |                          Error code                           |
00091  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
00092  * |                       OLD Netlink message header              |
00093  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
00094  * @endcode
00095  *
00096  * @par Example
00097  * @code
00098  * // Various methods exist to create/allocate a new netlink
00099  * // message. 
00100  * //
00101  * // nlmsg_alloc() will allocate an empty netlink message with
00102  * // a maximum payload size which defaults to the page size of
00103  * // the system. This default size can be modified using the
00104  * // function nlmsg_set_default_size().
00105  * struct nl_msg *msg = nlmsg_alloc();
00106  *
00107  * // Very often, the message type and message flags are known
00108  * // at allocation time while the other fields are auto generated:
00109  * struct nl_msg *msg = nlmsg_alloc_simple(MY_TYPE, MY_FLAGS);
00110  *
00111  * // Alternatively an existing netlink message header can be used
00112  * // to inherit the header values:
00113  * struct nlmsghdr hdr = {
00114  *      .nlmsg_type = MY_TYPE,
00115  *      .nlmsg_flags = MY_FLAGS,
00116  * };
00117  * struct nl_msg *msg = nlmsg_inherit(&hdr);
00118  *
00119  * // Last but not least, netlink messages received from netlink sockets
00120  * // can be converted into nl_msg objects using nlmsg_convert(). This
00121  * // will create a message with a maximum payload size which equals the
00122  * // length of the existing netlink message, therefore no more data can
00123  * // be appened without calling nlmsg_expand() first.
00124  * struct nl_msg *msg = nlmsg_convert(nlh_from_nl_sock);
00125  *
00126  * // Payload may be added to the message via nlmsg_append(). The fourth
00127  * // parameter specifies the number of alignment bytes the data should
00128  * // be padding with at the end. Common values are 0 to disable it or
00129  * // NLMSG_ALIGNTO to ensure proper netlink message padding.
00130  * nlmsg_append(msg, &mydata, sizeof(mydata), 0);
00131  *
00132  * // Sometimes it may be necessary to reserve room for data but defer
00133  * // the actual copying to a later point, nlmsg_reserve() can be used
00134  * // for this purpose:
00135  * void *data = nlmsg_reserve(msg, sizeof(mydata), NLMSG_ALIGNTO);
00136  *
00137  * // Attributes may be added using the attributes interface.
00138  *
00139  * // After successful use of the message, the memory must be freed
00140  * // using nlmsg_free()
00141  * nlmsg_free(msg);
00142  * @endcode
00143  * 
00144  * @par 4) Parsing messages
00145  * @code
00146  * int n;
00147  * unsigned char *buf;
00148  * struct nlmsghdr *hdr;
00149  *
00150  * n = nl_recv(handle, NULL, &buf);
00151  * 
00152  * hdr = (struct nlmsghdr *) buf;
00153  * while (nlmsg_ok(hdr, n)) {
00154  *      // Process message here...
00155  *      hdr = nlmsg_next(hdr, &n);
00156  * }
00157  * @endcode
00158  * @{
00159  */
00160 
00161 #include <netlink-local.h>
00162 #include <netlink/netlink.h>
00163 #include <netlink/utils.h>
00164 #include <netlink/cache.h>
00165 #include <netlink/attr.h>
00166 #include <linux/socket.h>
00167 
00168 static size_t default_msg_size;
00169 
00170 static void __init init_msg_size(void)
00171 {
00172         default_msg_size = getpagesize();
00173 }
00174 
00175 /**
00176  * @name Size Calculations
00177  * @{
00178  */
00179 
00180 /**
00181  * length of netlink message not including padding
00182  * @arg payload         length of message payload
00183  */
00184 int nlmsg_msg_size(int payload)
00185 {
00186         return NLMSG_HDRLEN + payload;
00187 }
00188 
00189 /**
00190  * length of netlink message including padding
00191  * @arg payload         length of message payload
00192  */
00193 int nlmsg_total_size(int payload)
00194 {
00195         return NLMSG_ALIGN(nlmsg_msg_size(payload));
00196 }
00197 
00198 /**
00199  * length of padding at the message's tail
00200  * @arg payload         length of message payload
00201  */
00202 int nlmsg_padlen(int payload)
00203 {
00204         return nlmsg_total_size(payload) - nlmsg_msg_size(payload);
00205 }
00206 
00207 /** @} */
00208 
00209 /**
00210  * @name Payload Access
00211  * @{
00212  */
00213 
00214 /**
00215  * head of message payload
00216  * @arg nlh             netlink messsage header
00217  */
00218 void *nlmsg_data(const struct nlmsghdr *nlh)
00219 {
00220         return (unsigned char *) nlh + NLMSG_HDRLEN;
00221 }
00222 
00223 void *nlmsg_tail(const struct nlmsghdr *nlh)
00224 {
00225         return (unsigned char *) nlh + NLMSG_ALIGN(nlh->nlmsg_len);
00226 }
00227 
00228 /**
00229  * length of message payload
00230  * @arg nlh             netlink message header
00231  */
00232 int nlmsg_len(const struct nlmsghdr *nlh)
00233 {
00234         return nlh->nlmsg_len - NLMSG_HDRLEN;
00235 }
00236 
00237 /** @} */
00238 
00239 /**
00240  * @name Attribute Access
00241  * @{
00242  */
00243 
00244 /**
00245  * head of attributes data
00246  * @arg nlh             netlink message header
00247  * @arg hdrlen          length of family specific header
00248  */
00249 struct nlattr *nlmsg_attrdata(const struct nlmsghdr *nlh, int hdrlen)
00250 {
00251         unsigned char *data = nlmsg_data(nlh);
00252         return (struct nlattr *) (data + NLMSG_ALIGN(hdrlen));
00253 }
00254 
00255 /**
00256  * length of attributes data
00257  * @arg nlh             netlink message header
00258  * @arg hdrlen          length of family specific header
00259  */
00260 int nlmsg_attrlen(const struct nlmsghdr *nlh, int hdrlen)
00261 {
00262         return nlmsg_len(nlh) - NLMSG_ALIGN(hdrlen);
00263 }
00264 
00265 /** @} */
00266 
00267 /**
00268  * @name Message Parsing
00269  * @{
00270  */
00271 
00272 int nlmsg_valid_hdr(const struct nlmsghdr *nlh, int hdrlen)
00273 {
00274         if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
00275                 return 0;
00276 
00277         return 1;
00278 }
00279 
00280 /**
00281  * check if the netlink message fits into the remaining bytes
00282  * @arg nlh             netlink message header
00283  * @arg remaining       number of bytes remaining in message stream
00284  */
00285 int nlmsg_ok(const struct nlmsghdr *nlh, int remaining)
00286 {
00287         return (remaining >= (int)sizeof(struct nlmsghdr) &&
00288                 nlh->nlmsg_len >= sizeof(struct nlmsghdr) &&
00289                 nlh->nlmsg_len <= remaining);
00290 }
00291 
00292 /**
00293  * next netlink message in message stream
00294  * @arg nlh             netlink message header
00295  * @arg remaining       number of bytes remaining in message stream
00296  *
00297  * @returns the next netlink message in the message stream and
00298  * decrements remaining by the size of the current message.
00299  */
00300 struct nlmsghdr *nlmsg_next(struct nlmsghdr *nlh, int *remaining)
00301 {
00302         int totlen = NLMSG_ALIGN(nlh->nlmsg_len);
00303 
00304         *remaining -= totlen;
00305 
00306         return (struct nlmsghdr *) ((unsigned char *) nlh + totlen);
00307 }
00308 
00309 /**
00310  * parse attributes of a netlink message
00311  * @arg nlh             netlink message header
00312  * @arg hdrlen          length of family specific header
00313  * @arg tb              destination array with maxtype+1 elements
00314  * @arg maxtype         maximum attribute type to be expected
00315  * @arg policy          validation policy
00316  *
00317  * See nla_parse()
00318  */
00319 int nlmsg_parse(struct nlmsghdr *nlh, int hdrlen, struct nlattr *tb[],
00320                 int maxtype, struct nla_policy *policy)
00321 {
00322         if (!nlmsg_valid_hdr(nlh, hdrlen))
00323                 return -NLE_MSG_TOOSHORT;
00324 
00325         return nla_parse(tb, maxtype, nlmsg_attrdata(nlh, hdrlen),
00326                          nlmsg_attrlen(nlh, hdrlen), policy);
00327 }
00328 
00329 /**
00330  * nlmsg_find_attr - find a specific attribute in a netlink message
00331  * @arg nlh             netlink message header
00332  * @arg hdrlen          length of familiy specific header
00333  * @arg attrtype        type of attribute to look for
00334  *
00335  * Returns the first attribute which matches the specified type.
00336  */
00337 struct nlattr *nlmsg_find_attr(struct nlmsghdr *nlh, int hdrlen, int attrtype)
00338 {
00339         return nla_find(nlmsg_attrdata(nlh, hdrlen),
00340                         nlmsg_attrlen(nlh, hdrlen), attrtype);
00341 }
00342 
00343 /**
00344  * nlmsg_validate - validate a netlink message including attributes
00345  * @arg nlh             netlinket message header
00346  * @arg hdrlen          length of familiy specific header
00347  * @arg maxtype         maximum attribute type to be expected
00348  * @arg policy          validation policy
00349  */
00350 int nlmsg_validate(struct nlmsghdr *nlh, int hdrlen, int maxtype,
00351                    struct nla_policy *policy)
00352 {
00353         if (!nlmsg_valid_hdr(nlh, hdrlen))
00354                 return -NLE_MSG_TOOSHORT;
00355 
00356         return nla_validate(nlmsg_attrdata(nlh, hdrlen),
00357                             nlmsg_attrlen(nlh, hdrlen), maxtype, policy);
00358 }
00359 
00360 /** @} */
00361 
00362 /**
00363  * @name Message Building/Access
00364  * @{
00365  */
00366 
00367 static struct nl_msg *__nlmsg_alloc(size_t len)
00368 {
00369         struct nl_msg *nm;
00370 
00371         nm = calloc(1, sizeof(*nm));
00372         if (!nm)
00373                 goto errout;
00374 
00375         nm->nm_refcnt = 1;
00376 
00377         nm->nm_nlh = malloc(len);
00378         if (!nm->nm_nlh)
00379                 goto errout;
00380 
00381         memset(nm->nm_nlh, 0, sizeof(struct nlmsghdr));
00382 
00383         nm->nm_protocol = -1;
00384         nm->nm_size = len;
00385         nm->nm_nlh->nlmsg_len = nlmsg_total_size(0);
00386 
00387         NL_DBG(2, "msg %p: Allocated new message, maxlen=%zu\n", nm, len);
00388 
00389         return nm;
00390 errout:
00391         free(nm);
00392         return NULL;
00393 }
00394 
00395 /**
00396  * Allocate a new netlink message with the default maximum payload size.
00397  *
00398  * Allocates a new netlink message without any further payload. The
00399  * maximum payload size defaults to PAGESIZE or as otherwise specified
00400  * with nlmsg_set_default_size().
00401  *
00402  * @return Newly allocated netlink message or NULL.
00403  */
00404 struct nl_msg *nlmsg_alloc(void)
00405 {
00406         return __nlmsg_alloc(default_msg_size);
00407 }
00408 
00409 /**
00410  * Allocate a new netlink message with maximum payload size specified.
00411  */
00412 struct nl_msg *nlmsg_alloc_size(size_t max)
00413 {
00414         return __nlmsg_alloc(max);
00415 }
00416 
00417 /**
00418  * Allocate a new netlink message and inherit netlink message header
00419  * @arg hdr             Netlink message header template
00420  *
00421  * Allocates a new netlink message and inherits the original message
00422  * header. If \a hdr is not NULL it will be used as a template for
00423  * the netlink message header, otherwise the header is left blank.
00424  * 
00425  * @return Newly allocated netlink message or NULL
00426  */ 
00427 struct nl_msg *nlmsg_inherit(struct nlmsghdr *hdr)
00428 {
00429         struct nl_msg *nm;
00430 
00431         nm = nlmsg_alloc();
00432         if (nm && hdr) {
00433                 struct nlmsghdr *new = nm->nm_nlh;
00434 
00435                 new->nlmsg_type = hdr->nlmsg_type;
00436                 new->nlmsg_flags = hdr->nlmsg_flags;
00437                 new->nlmsg_seq = hdr->nlmsg_seq;
00438                 new->nlmsg_pid = hdr->nlmsg_pid;
00439         }
00440 
00441         return nm;
00442 }
00443 
00444 /**
00445  * Allocate a new netlink message
00446  * @arg nlmsgtype       Netlink message type
00447  * @arg flags           Message flags.
00448  *
00449  * @return Newly allocated netlink message or NULL.
00450  */
00451 struct nl_msg *nlmsg_alloc_simple(int nlmsgtype, int flags)
00452 {
00453         struct nl_msg *msg;
00454         struct nlmsghdr nlh = {
00455                 .nlmsg_type = nlmsgtype,
00456                 .nlmsg_flags = flags,
00457         };
00458 
00459         msg = nlmsg_inherit(&nlh);
00460         if (msg)
00461                 NL_DBG(2, "msg %p: Allocated new simple message\n", msg);
00462 
00463         return msg;
00464 }
00465 
00466 /**
00467  * Set the default maximum message payload size for allocated messages
00468  * @arg max             Size of payload in bytes.
00469  */
00470 void nlmsg_set_default_size(size_t max)
00471 {
00472         if (max < nlmsg_total_size(0))
00473                 max = nlmsg_total_size(0);
00474 
00475         default_msg_size = max;
00476 }
00477 
00478 /**
00479  * Convert a netlink message received from a netlink socket to a nl_msg
00480  * @arg hdr             Netlink message received from netlink socket.
00481  *
00482  * Allocates a new netlink message and copies all of the data pointed to
00483  * by \a hdr into the new message object.
00484  *
00485  * @return Newly allocated netlink message or NULL.
00486  */
00487 struct nl_msg *nlmsg_convert(struct nlmsghdr *hdr)
00488 {
00489         struct nl_msg *nm;
00490 
00491         nm = __nlmsg_alloc(NLMSG_ALIGN(hdr->nlmsg_len));
00492         if (!nm)
00493                 goto errout;
00494 
00495         memcpy(nm->nm_nlh, hdr, hdr->nlmsg_len);
00496 
00497         return nm;
00498 errout:
00499         nlmsg_free(nm);
00500         return NULL;
00501 }
00502 
00503 /**
00504  * Reserve room for additional data in a netlink message
00505  * @arg n               netlink message
00506  * @arg len             length of additional data to reserve room for
00507  * @arg pad             number of bytes to align data to
00508  *
00509  * Reserves room for additional data at the tail of the an
00510  * existing netlink message. Eventual padding required will
00511  * be zeroed out.
00512  *
00513  * @return Pointer to start of additional data tailroom or NULL.
00514  */
00515 void *nlmsg_reserve(struct nl_msg *n, size_t len, int pad)
00516 {
00517         void *buf = n->nm_nlh;
00518         size_t nlmsg_len = n->nm_nlh->nlmsg_len;
00519         size_t tlen;
00520 
00521         tlen = pad ? ((len + (pad - 1)) & ~(pad - 1)) : len;
00522 
00523         if ((tlen + nlmsg_len) > n->nm_size)
00524                 return NULL;
00525 
00526         buf += nlmsg_len;
00527         n->nm_nlh->nlmsg_len += tlen;
00528 
00529         if (tlen > len)
00530                 memset(buf + len, 0, tlen - len);
00531 
00532         NL_DBG(2, "msg %p: Reserved %zu bytes, pad=%d, nlmsg_len=%d\n",
00533                   n, len, pad, n->nm_nlh->nlmsg_len);
00534 
00535         return buf;
00536 }
00537 
00538 /**
00539  * Append data to tail of a netlink message
00540  * @arg n               netlink message
00541  * @arg data            data to add
00542  * @arg len             length of data
00543  * @arg pad             Number of bytes to align data to.
00544  *
00545  * Extends the netlink message as needed and appends the data of given
00546  * length to the message. 
00547  *
00548  * @return 0 on success or a negative error code
00549  */
00550 int nlmsg_append(struct nl_msg *n, void *data, size_t len, int pad)
00551 {
00552         void *tmp;
00553 
00554         tmp = nlmsg_reserve(n, len, pad);
00555         if (tmp == NULL)
00556                 return -NLE_NOMEM;
00557 
00558         memcpy(tmp, data, len);
00559         NL_DBG(2, "msg %p: Appended %zu bytes with padding %d\n", n, len, pad);
00560 
00561         return 0;
00562 }
00563 
00564 /**
00565  * Expand maximum payload size of a netlink message
00566  * @arg n               Netlink message.
00567  * @arg newlen          New maximum payload size.
00568  *
00569  * Reallocates the payload section of a netlink message and increases
00570  * the maximum payload size of the message.
00571  *
00572  * @note Any pointers pointing to old payload block will be stale and
00573  *       need to be refetched. Therfore, do not expand while constructing
00574  *       nested attributes or while reserved data blocks are held.
00575  *
00576  * @return 0 on success or a negative error code.
00577  */
00578 int nlmsg_expand(struct nl_msg *n, size_t newlen)
00579 {
00580         void *tmp;
00581 
00582         if (newlen <= n->nm_size)
00583                 return -NLE_INVAL;
00584 
00585         tmp = realloc(n->nm_nlh, newlen);
00586         if (tmp == NULL)
00587                 return -NLE_NOMEM;
00588 
00589         n->nm_nlh = tmp;
00590         n->nm_size = newlen;
00591 
00592         return 0;
00593 }
00594 
00595 /**
00596  * Add a netlink message header to a netlink message
00597  * @arg n               netlink message
00598  * @arg pid             netlink process id or NL_AUTO_PID
00599  * @arg seq             sequence number of message or NL_AUTO_SEQ
00600  * @arg type            message type
00601  * @arg payload         length of message payload
00602  * @arg flags           message flags
00603  *
00604  * Adds or overwrites the netlink message header in an existing message
00605  * object. If \a payload is greater-than zero additional room will be
00606  * reserved, f.e. for family specific headers. It can be accesed via
00607  * nlmsg_data().
00608  *
00609  * @return A pointer to the netlink message header or NULL.
00610  */
00611 struct nlmsghdr *nlmsg_put(struct nl_msg *n, uint32_t pid, uint32_t seq,
00612                            int type, int payload, int flags)
00613 {
00614         struct nlmsghdr *nlh;
00615 
00616         if (n->nm_nlh->nlmsg_len < NLMSG_HDRLEN)
00617                 BUG();
00618 
00619         nlh = (struct nlmsghdr *) n->nm_nlh;
00620         nlh->nlmsg_type = type;
00621         nlh->nlmsg_flags = flags;
00622         nlh->nlmsg_pid = pid;
00623         nlh->nlmsg_seq = seq;
00624 
00625         NL_DBG(2, "msg %p: Added netlink header type=%d, flags=%d, pid=%d, "
00626                   "seq=%d\n", n, type, flags, pid, seq);
00627 
00628         if (payload > 0 &&
00629             nlmsg_reserve(n, payload, NLMSG_ALIGNTO) == NULL)
00630                 return NULL;
00631 
00632         return nlh;
00633 }
00634 
00635 /**
00636  * Return actual netlink message
00637  * @arg n               netlink message
00638  * 
00639  * Returns the actual netlink message casted to the type of the netlink
00640  * message header.
00641  * 
00642  * @return A pointer to the netlink message.
00643  */
00644 struct nlmsghdr *nlmsg_hdr(struct nl_msg *n)
00645 {
00646         return n->nm_nlh;
00647 }
00648 
00649 /**
00650  * Acquire a reference on a netlink message
00651  * @arg msg             message to acquire reference from
00652  */
00653 void nlmsg_get(struct nl_msg *msg)
00654 {
00655         msg->nm_refcnt++;
00656         NL_DBG(4, "New reference to message %p, total %d\n",
00657                msg, msg->nm_refcnt);
00658 }
00659 
00660 /**
00661  * Release a reference from an netlink message
00662  * @arg msg             message to release reference from
00663  *
00664  * Frees memory after the last reference has been released.
00665  */
00666 void nlmsg_free(struct nl_msg *msg)
00667 {
00668         if (!msg)
00669                 return;
00670 
00671         msg->nm_refcnt--;
00672         NL_DBG(4, "Returned message reference %p, %d remaining\n",
00673                msg, msg->nm_refcnt);
00674 
00675         if (msg->nm_refcnt < 0)
00676                 BUG();
00677 
00678         if (msg->nm_refcnt <= 0) {
00679                 free(msg->nm_nlh);
00680                 free(msg);
00681                 NL_DBG(2, "msg %p: Freed\n", msg);
00682         }
00683 }
00684 
00685 /** @} */
00686 
00687 /**
00688  * @name Attributes
00689  * @{
00690  */
00691 
00692 void nlmsg_set_proto(struct nl_msg *msg, int protocol)
00693 {
00694         msg->nm_protocol = protocol;
00695 }
00696 
00697 int nlmsg_get_proto(struct nl_msg *msg)
00698 {
00699         return msg->nm_protocol;
00700 }
00701 
00702 size_t nlmsg_get_max_size(struct nl_msg *msg)
00703 {
00704         return msg->nm_size;
00705 }
00706 
00707 void nlmsg_set_src(struct nl_msg *msg, struct sockaddr_nl *addr)
00708 {
00709         memcpy(&msg->nm_src, addr, sizeof(*addr));
00710 }
00711 
00712 struct sockaddr_nl *nlmsg_get_src(struct nl_msg *msg)
00713 {
00714         return &msg->nm_src;
00715 }
00716 
00717 void nlmsg_set_dst(struct nl_msg *msg, struct sockaddr_nl *addr)
00718 {
00719         memcpy(&msg->nm_dst, addr, sizeof(*addr));
00720 }
00721 
00722 struct sockaddr_nl *nlmsg_get_dst(struct nl_msg *msg)
00723 {
00724         return &msg->nm_dst;
00725 }
00726 
00727 void nlmsg_set_creds(struct nl_msg *msg, struct ucred *creds)
00728 {
00729         memcpy(&msg->nm_creds, creds, sizeof(*creds));
00730         msg->nm_flags |= NL_MSG_CRED_PRESENT;
00731 }
00732 
00733 struct ucred *nlmsg_get_creds(struct nl_msg *msg)
00734 {
00735         if (msg->nm_flags & NL_MSG_CRED_PRESENT)
00736                 return &msg->nm_creds;
00737         return NULL;
00738 }
00739 
00740 /** @} */
00741 
00742 /**
00743  * @name Netlink Message Type Translations
00744  * @{
00745  */
00746 
00747 static struct trans_tbl nl_msgtypes[] = {
00748         __ADD(NLMSG_NOOP,NOOP)
00749         __ADD(NLMSG_ERROR,ERROR)
00750         __ADD(NLMSG_DONE,DONE)
00751         __ADD(NLMSG_OVERRUN,OVERRUN)
00752 };
00753 
00754 char *nl_nlmsgtype2str(int type, char *buf, size_t size)
00755 {
00756         return __type2str(type, buf, size, nl_msgtypes,
00757                           ARRAY_SIZE(nl_msgtypes));
00758 }
00759 
00760 int nl_str2nlmsgtype(const char *name)
00761 {
00762         return __str2type(name, nl_msgtypes, ARRAY_SIZE(nl_msgtypes));
00763 }
00764 
00765 /** @} */
00766 
00767 /**
00768  * @name Netlink Message Flags Translations
00769  * @{
00770  */
00771 
00772 char *nl_nlmsg_flags2str(int flags, char *buf, size_t len)
00773 {
00774         memset(buf, 0, len);
00775 
00776 #define PRINT_FLAG(f) \
00777         if (flags & NLM_F_##f) { \
00778                 flags &= ~NLM_F_##f; \
00779                 strncat(buf, #f, len - strlen(buf) - 1); \
00780                 if (flags) \
00781                         strncat(buf, ",", len - strlen(buf) - 1); \
00782         }
00783         
00784         PRINT_FLAG(REQUEST);
00785         PRINT_FLAG(MULTI);
00786         PRINT_FLAG(ACK);
00787         PRINT_FLAG(ECHO);
00788         PRINT_FLAG(ROOT);
00789         PRINT_FLAG(MATCH);
00790         PRINT_FLAG(ATOMIC);
00791         PRINT_FLAG(REPLACE);
00792         PRINT_FLAG(EXCL);
00793         PRINT_FLAG(CREATE);
00794         PRINT_FLAG(APPEND);
00795 
00796         if (flags) {
00797                 char s[32];
00798                 snprintf(s, sizeof(s), "0x%x", flags);
00799                 strncat(buf, s, len - strlen(buf) - 1);
00800         }
00801 #undef PRINT_FLAG
00802 
00803         return buf;
00804 }
00805 
00806 /** @} */
00807 
00808 /**
00809  * @name Direct Parsing
00810  * @{
00811  */
00812 
00813 /** @cond SKIP */
00814 struct dp_xdata {
00815         void (*cb)(struct nl_object *, void *);
00816         void *arg;
00817 };
00818 /** @endcond */
00819 
00820 static int parse_cb(struct nl_object *obj, struct nl_parser_param *p)
00821 {
00822         struct dp_xdata *x = p->pp_arg;
00823 
00824         x->cb(obj, x->arg);
00825         return 0;
00826 }
00827 
00828 int nl_msg_parse(struct nl_msg *msg, void (*cb)(struct nl_object *, void *),
00829                  void *arg)
00830 {
00831         struct nl_cache_ops *ops;
00832         struct nl_parser_param p = {
00833                 .pp_cb = parse_cb
00834         };
00835         struct dp_xdata x = {
00836                 .cb = cb,
00837                 .arg = arg,
00838         };
00839 
00840         ops = nl_cache_ops_associate(nlmsg_get_proto(msg),
00841                                      nlmsg_hdr(msg)->nlmsg_type);
00842         if (ops == NULL)
00843                 return -NLE_MSGTYPE_NOSUPPORT;
00844         p.pp_arg = &x;
00845 
00846         return nl_cache_parse(ops, NULL, nlmsg_hdr(msg), &p);
00847 }
00848 
00849 /** @} */
00850 
00851 /**
00852  * @name Dumping
00853  * @{
00854  */
00855 
00856 static void prefix_line(FILE *ofd, int prefix)
00857 {
00858         int i;
00859 
00860         for (i = 0; i < prefix; i++)
00861                 fprintf(ofd, "  ");
00862 }
00863 
00864 static inline void dump_hex(FILE *ofd, char *start, int len, int prefix)
00865 {
00866         int i, a, c, limit;
00867         char ascii[21] = {0};
00868 
00869         limit = 18 - (prefix * 2);
00870         prefix_line(ofd, prefix);
00871         fprintf(ofd, "    ");
00872 
00873         for (i = 0, a = 0, c = 0; i < len; i++) {
00874                 int v = *(uint8_t *) (start + i);
00875 
00876                 fprintf(ofd, "%02x ", v);
00877                 ascii[a++] = isprint(v) ? v : '.';
00878 
00879                 if (c == limit-1) {
00880                         fprintf(ofd, "%s\n", ascii);
00881                         if (i < (len - 1)) {
00882                                 prefix_line(ofd, prefix);
00883                                 fprintf(ofd, "    ");
00884                         }
00885                         a = c = 0;
00886                         memset(ascii, 0, sizeof(ascii));
00887                 } else
00888                         c++;
00889         }
00890 
00891         if (c != 0) {
00892                 for (i = 0; i < (limit - c); i++)
00893                         fprintf(ofd, "   ");
00894                 fprintf(ofd, "%s\n", ascii);
00895         }
00896 }
00897 
00898 static void print_hdr(FILE *ofd, struct nl_msg *msg)
00899 {
00900         struct nlmsghdr *nlh = nlmsg_hdr(msg);
00901         struct nl_cache_ops *ops;
00902         struct nl_msgtype *mt;
00903         char buf[128];
00904 
00905         fprintf(ofd, "    .nlmsg_len = %d\n", nlh->nlmsg_len);
00906 
00907         ops = nl_cache_ops_associate(nlmsg_get_proto(msg), nlh->nlmsg_type);
00908         if (ops) {
00909                 mt = nl_msgtype_lookup(ops, nlh->nlmsg_type);
00910                 if (!mt)
00911                         BUG();
00912 
00913                 snprintf(buf, sizeof(buf), "%s::%s", ops->co_name, mt->mt_name);
00914         } else
00915                 nl_nlmsgtype2str(nlh->nlmsg_type, buf, sizeof(buf));
00916 
00917         fprintf(ofd, "    .nlmsg_type = %d <%s>\n", nlh->nlmsg_type, buf);
00918         fprintf(ofd, "    .nlmsg_flags = %d <%s>\n", nlh->nlmsg_flags,
00919                 nl_nlmsg_flags2str(nlh->nlmsg_flags, buf, sizeof(buf)));
00920         fprintf(ofd, "    .nlmsg_seq = %d\n", nlh->nlmsg_seq);
00921         fprintf(ofd, "    .nlmsg_pid = %d\n", nlh->nlmsg_pid);
00922 
00923 }
00924 
00925 static void dump_attrs(FILE *ofd, struct nlattr *attrs, int attrlen,
00926                        int prefix)
00927 {
00928         int rem;
00929         struct nlattr *nla;
00930 
00931         nla_for_each_attr(nla, attrs, attrlen, rem) {
00932                 int padlen, alen = nla_len(nla);
00933 
00934                 prefix_line(ofd, prefix);
00935                 fprintf(ofd, "  [ATTR %02d%s] %d octets\n", nla_type(nla),
00936                         nla->nla_type & NLA_F_NESTED ? " NESTED" : "",
00937                         alen);
00938 
00939                 if (nla->nla_type & NLA_F_NESTED)
00940                         dump_attrs(ofd, nla_data(nla), alen, prefix+1);
00941                 else
00942                         dump_hex(ofd, nla_data(nla), alen, prefix);
00943 
00944                 padlen = nla_padlen(alen);
00945                 if (padlen > 0) {
00946                         prefix_line(ofd, prefix);
00947                         fprintf(ofd, "  [PADDING] %d octets\n",
00948                                 padlen);
00949                         dump_hex(ofd, nla_data(nla) + alen,
00950                                  padlen, prefix);
00951                 }
00952         }
00953 
00954         if (rem) {
00955                 prefix_line(ofd, prefix);
00956                 fprintf(ofd, "  [LEFTOVER] %d octets\n", rem);
00957         }
00958 }
00959 
00960 /**
00961  * Dump message in human readable format to file descriptor
00962  * @arg msg             Message to print
00963  * @arg ofd             File descriptor.
00964  */
00965 void nl_msg_dump(struct nl_msg *msg, FILE *ofd)
00966 {
00967         struct nlmsghdr *hdr = nlmsg_hdr(msg);
00968         
00969         fprintf(ofd, 
00970         "--------------------------   BEGIN NETLINK MESSAGE "
00971         "---------------------------\n");
00972 
00973         fprintf(ofd, "  [HEADER] %Zu octets\n", sizeof(struct nlmsghdr));
00974         print_hdr(ofd, msg);
00975 
00976         if (hdr->nlmsg_type == NLMSG_ERROR &&
00977             hdr->nlmsg_len >= nlmsg_msg_size(sizeof(struct nlmsgerr))) {
00978                 struct nl_msg *errmsg;
00979                 struct nlmsgerr *err = nlmsg_data(hdr);
00980 
00981                 fprintf(ofd, "  [ERRORMSG] %Zu octets\n", sizeof(*err));
00982                 fprintf(ofd, "    .error = %d \"%s\"\n", err->error,
00983                         strerror(-err->error));
00984                 fprintf(ofd, "  [ORIGINAL MESSAGE] %Zu octets\n", sizeof(*hdr));
00985 
00986                 errmsg = nlmsg_inherit(&err->msg);
00987                 print_hdr(ofd, errmsg);
00988                 nlmsg_free(errmsg);
00989         } else if (nlmsg_len(hdr) > 0) {
00990                 struct nl_cache_ops *ops;
00991                 int payloadlen = nlmsg_len(hdr);
00992                 int attrlen = 0;
00993 
00994                 ops = nl_cache_ops_associate(nlmsg_get_proto(msg),
00995                                              hdr->nlmsg_type);
00996                 if (ops) {
00997                         attrlen = nlmsg_attrlen(hdr, ops->co_hdrsize);
00998                         payloadlen -= attrlen;
00999                 }
01000 
01001                 fprintf(ofd, "  [PAYLOAD] %d octets\n", payloadlen);
01002                 dump_hex(ofd, nlmsg_data(hdr), payloadlen, 0);
01003 
01004                 if (attrlen) {
01005                         struct nlattr *attrs;
01006                         int attrlen;
01007                         
01008                         attrs = nlmsg_attrdata(hdr, ops->co_hdrsize);
01009                         attrlen = nlmsg_attrlen(hdr, ops->co_hdrsize);
01010                         dump_attrs(ofd, attrs, attrlen, 0);
01011                 }
01012         }
01013 
01014         fprintf(ofd, 
01015         "---------------------------  END NETLINK MESSAGE   "
01016         "---------------------------\n");
01017 }
01018 
01019 /** @} */
01020 
01021 /** @} */