libnl  3.2.3
/build/buildd/libnl3-3.2.3/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 (struct nlmsghdr) 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  * Calculates size of netlink message based on payload length.
00182  * @arg payload         Length of payload
00183  *
00184  * @return size of netlink message without padding.
00185  */
00186 int nlmsg_size(int payload)
00187 {
00188         return NLMSG_HDRLEN + payload;
00189 }
00190 
00191 static int nlmsg_msg_size(int payload)
00192 {
00193         return nlmsg_size(payload);
00194 }
00195 
00196 /**
00197  * Calculates size of netlink message including padding based on payload length
00198  * @arg payload         Length of payload
00199  *
00200  * This function is idential to nlmsg_size() + nlmsg_padlen().
00201  *
00202  * @return Size of netlink message including padding.
00203  */
00204 int nlmsg_total_size(int payload)
00205 {
00206         return NLMSG_ALIGN(nlmsg_msg_size(payload));
00207 }
00208 
00209 /**
00210  * Size of padding that needs to be added at end of message
00211  * @arg payload         Length of payload
00212  *
00213  * Calculates the number of bytes of padding which is required to be added to
00214  * the end of the message to ensure that the next netlink message header begins
00215  * properly aligned to NLMSG_ALIGNTO.
00216  *
00217  * @return Number of bytes of padding needed.
00218  */
00219 int nlmsg_padlen(int payload)
00220 {
00221         return nlmsg_total_size(payload) - nlmsg_msg_size(payload);
00222 }
00223 
00224 /** @} */
00225 
00226 /**
00227  * @name Access to Message Payload
00228  * @{
00229  */
00230 
00231 /**
00232  * Return pointer to message payload
00233  * @arg nlh             Netlink message header
00234  *
00235  * @return Pointer to start of message payload.
00236  */
00237 void *nlmsg_data(const struct nlmsghdr *nlh)
00238 {
00239         return (unsigned char *) nlh + NLMSG_HDRLEN;
00240 }
00241 
00242 void *nlmsg_tail(const struct nlmsghdr *nlh)
00243 {
00244         return (unsigned char *) nlh + NLMSG_ALIGN(nlh->nlmsg_len);
00245 }
00246 
00247 /**
00248  * Return length of message payload
00249  * @arg nlh             Netlink message header
00250  *
00251  * @return Length of message payload in bytes.
00252  */
00253 int nlmsg_datalen(const struct nlmsghdr *nlh)
00254 {
00255         return nlh->nlmsg_len - NLMSG_HDRLEN;
00256 }
00257 
00258 static int nlmsg_len(const struct nlmsghdr *nlh)
00259 {
00260         return nlmsg_datalen(nlh);
00261 }
00262 
00263 /** @} */
00264 
00265 /**
00266  * @name Attribute Access
00267  * @{
00268  */
00269 
00270 /**
00271  * head of attributes data
00272  * @arg nlh             netlink message header
00273  * @arg hdrlen          length of family specific header
00274  */
00275 struct nlattr *nlmsg_attrdata(const struct nlmsghdr *nlh, int hdrlen)
00276 {
00277         unsigned char *data = nlmsg_data(nlh);
00278         return (struct nlattr *) (data + NLMSG_ALIGN(hdrlen));
00279 }
00280 
00281 /**
00282  * length of attributes data
00283  * @arg nlh             netlink message header
00284  * @arg hdrlen          length of family specific header
00285  */
00286 int nlmsg_attrlen(const struct nlmsghdr *nlh, int hdrlen)
00287 {
00288         return nlmsg_len(nlh) - NLMSG_ALIGN(hdrlen);
00289 }
00290 
00291 /** @} */
00292 
00293 /**
00294  * @name Message Parsing
00295  * @{
00296  */
00297 
00298 int nlmsg_valid_hdr(const struct nlmsghdr *nlh, int hdrlen)
00299 {
00300         if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
00301                 return 0;
00302 
00303         return 1;
00304 }
00305 
00306 /**
00307  * check if the netlink message fits into the remaining bytes
00308  * @arg nlh             netlink message header
00309  * @arg remaining       number of bytes remaining in message stream
00310  */
00311 int nlmsg_ok(const struct nlmsghdr *nlh, int remaining)
00312 {
00313         return (remaining >= (int)sizeof(struct nlmsghdr) &&
00314                 nlh->nlmsg_len >= sizeof(struct nlmsghdr) &&
00315                 nlh->nlmsg_len <= remaining);
00316 }
00317 
00318 /**
00319  * next netlink message in message stream
00320  * @arg nlh             netlink message header
00321  * @arg remaining       number of bytes remaining in message stream
00322  *
00323  * @returns the next netlink message in the message stream and
00324  * decrements remaining by the size of the current message.
00325  */
00326 struct nlmsghdr *nlmsg_next(struct nlmsghdr *nlh, int *remaining)
00327 {
00328         int totlen = NLMSG_ALIGN(nlh->nlmsg_len);
00329 
00330         *remaining -= totlen;
00331 
00332         return (struct nlmsghdr *) ((unsigned char *) nlh + totlen);
00333 }
00334 
00335 /**
00336  * parse attributes of a netlink message
00337  * @arg nlh             netlink message header
00338  * @arg hdrlen          length of family specific header
00339  * @arg tb              destination array with maxtype+1 elements
00340  * @arg maxtype         maximum attribute type to be expected
00341  * @arg policy          validation policy
00342  *
00343  * See nla_parse()
00344  */
00345 int nlmsg_parse(struct nlmsghdr *nlh, int hdrlen, struct nlattr *tb[],
00346                 int maxtype, struct nla_policy *policy)
00347 {
00348         if (!nlmsg_valid_hdr(nlh, hdrlen))
00349                 return -NLE_MSG_TOOSHORT;
00350 
00351         return nla_parse(tb, maxtype, nlmsg_attrdata(nlh, hdrlen),
00352                          nlmsg_attrlen(nlh, hdrlen), policy);
00353 }
00354 
00355 /**
00356  * nlmsg_find_attr - find a specific attribute in a netlink message
00357  * @arg nlh             netlink message header
00358  * @arg hdrlen          length of familiy specific header
00359  * @arg attrtype        type of attribute to look for
00360  *
00361  * Returns the first attribute which matches the specified type.
00362  */
00363 struct nlattr *nlmsg_find_attr(struct nlmsghdr *nlh, int hdrlen, int attrtype)
00364 {
00365         return nla_find(nlmsg_attrdata(nlh, hdrlen),
00366                         nlmsg_attrlen(nlh, hdrlen), attrtype);
00367 }
00368 
00369 /**
00370  * nlmsg_validate - validate a netlink message including attributes
00371  * @arg nlh             netlinket message header
00372  * @arg hdrlen          length of familiy specific header
00373  * @arg maxtype         maximum attribute type to be expected
00374  * @arg policy          validation policy
00375  */
00376 int nlmsg_validate(struct nlmsghdr *nlh, int hdrlen, int maxtype,
00377                    struct nla_policy *policy)
00378 {
00379         if (!nlmsg_valid_hdr(nlh, hdrlen))
00380                 return -NLE_MSG_TOOSHORT;
00381 
00382         return nla_validate(nlmsg_attrdata(nlh, hdrlen),
00383                             nlmsg_attrlen(nlh, hdrlen), maxtype, policy);
00384 }
00385 
00386 /** @} */
00387 
00388 /**
00389  * @name Message Building/Access
00390  * @{
00391  */
00392 
00393 static struct nl_msg *__nlmsg_alloc(size_t len)
00394 {
00395         struct nl_msg *nm;
00396 
00397         if (len < sizeof(struct nlmsghdr))
00398                 len = sizeof(struct nlmsghdr);
00399 
00400         nm = calloc(1, sizeof(*nm));
00401         if (!nm)
00402                 goto errout;
00403 
00404         nm->nm_refcnt = 1;
00405 
00406         nm->nm_nlh = calloc(1, len);
00407         if (!nm->nm_nlh)
00408                 goto errout;
00409 
00410         memset(nm->nm_nlh, 0, sizeof(struct nlmsghdr));
00411 
00412         nm->nm_protocol = -1;
00413         nm->nm_size = len;
00414         nm->nm_nlh->nlmsg_len = nlmsg_total_size(0);
00415 
00416         NL_DBG(2, "msg %p: Allocated new message, maxlen=%zu\n", nm, len);
00417 
00418         return nm;
00419 errout:
00420         free(nm);
00421         return NULL;
00422 }
00423 
00424 /**
00425  * Allocate a new netlink message with the default maximum payload size.
00426  *
00427  * Allocates a new netlink message without any further payload. The
00428  * maximum payload size defaults to PAGESIZE or as otherwise specified
00429  * with nlmsg_set_default_size().
00430  *
00431  * @return Newly allocated netlink message or NULL.
00432  */
00433 struct nl_msg *nlmsg_alloc(void)
00434 {
00435         return __nlmsg_alloc(default_msg_size);
00436 }
00437 
00438 /**
00439  * Allocate a new netlink message with maximum payload size specified.
00440  */
00441 struct nl_msg *nlmsg_alloc_size(size_t max)
00442 {
00443         return __nlmsg_alloc(max);
00444 }
00445 
00446 /**
00447  * Allocate a new netlink message and inherit netlink message header
00448  * @arg hdr             Netlink message header template
00449  *
00450  * Allocates a new netlink message and inherits the original message
00451  * header. If \a hdr is not NULL it will be used as a template for
00452  * the netlink message header, otherwise the header is left blank.
00453  * 
00454  * @return Newly allocated netlink message or NULL
00455  */ 
00456 struct nl_msg *nlmsg_inherit(struct nlmsghdr *hdr)
00457 {
00458         struct nl_msg *nm;
00459 
00460         nm = nlmsg_alloc();
00461         if (nm && hdr) {
00462                 struct nlmsghdr *new = nm->nm_nlh;
00463 
00464                 new->nlmsg_type = hdr->nlmsg_type;
00465                 new->nlmsg_flags = hdr->nlmsg_flags;
00466                 new->nlmsg_seq = hdr->nlmsg_seq;
00467                 new->nlmsg_pid = hdr->nlmsg_pid;
00468         }
00469 
00470         return nm;
00471 }
00472 
00473 /**
00474  * Allocate a new netlink message
00475  * @arg nlmsgtype       Netlink message type
00476  * @arg flags           Message flags.
00477  *
00478  * @return Newly allocated netlink message or NULL.
00479  */
00480 struct nl_msg *nlmsg_alloc_simple(int nlmsgtype, int flags)
00481 {
00482         struct nl_msg *msg;
00483         struct nlmsghdr nlh = {
00484                 .nlmsg_type = nlmsgtype,
00485                 .nlmsg_flags = flags,
00486         };
00487 
00488         msg = nlmsg_inherit(&nlh);
00489         if (msg)
00490                 NL_DBG(2, "msg %p: Allocated new simple message\n", msg);
00491 
00492         return msg;
00493 }
00494 
00495 /**
00496  * Set the default maximum message payload size for allocated messages
00497  * @arg max             Size of payload in bytes.
00498  */
00499 void nlmsg_set_default_size(size_t max)
00500 {
00501         if (max < nlmsg_total_size(0))
00502                 max = nlmsg_total_size(0);
00503 
00504         default_msg_size = max;
00505 }
00506 
00507 /**
00508  * Convert a netlink message received from a netlink socket to a nl_msg
00509  * @arg hdr             Netlink message received from netlink socket.
00510  *
00511  * Allocates a new netlink message and copies all of the data pointed to
00512  * by \a hdr into the new message object.
00513  *
00514  * @return Newly allocated netlink message or NULL.
00515  */
00516 struct nl_msg *nlmsg_convert(struct nlmsghdr *hdr)
00517 {
00518         struct nl_msg *nm;
00519 
00520         nm = __nlmsg_alloc(NLMSG_ALIGN(hdr->nlmsg_len));
00521         if (!nm)
00522                 goto errout;
00523 
00524         memcpy(nm->nm_nlh, hdr, hdr->nlmsg_len);
00525 
00526         return nm;
00527 errout:
00528         nlmsg_free(nm);
00529         return NULL;
00530 }
00531 
00532 /**
00533  * Reserve room for additional data in a netlink message
00534  * @arg n               netlink message
00535  * @arg len             length of additional data to reserve room for
00536  * @arg pad             number of bytes to align data to
00537  *
00538  * Reserves room for additional data at the tail of the an
00539  * existing netlink message. Eventual padding required will
00540  * be zeroed out.
00541  *
00542  * @return Pointer to start of additional data tailroom or NULL.
00543  */
00544 void *nlmsg_reserve(struct nl_msg *n, size_t len, int pad)
00545 {
00546         void *buf = n->nm_nlh;
00547         size_t nlmsg_len = n->nm_nlh->nlmsg_len;
00548         size_t tlen;
00549 
00550         tlen = pad ? ((len + (pad - 1)) & ~(pad - 1)) : len;
00551 
00552         if ((tlen + nlmsg_len) > n->nm_size)
00553                 return NULL;
00554 
00555         buf += nlmsg_len;
00556         n->nm_nlh->nlmsg_len += tlen;
00557 
00558         if (tlen > len)
00559                 memset(buf + len, 0, tlen - len);
00560 
00561         NL_DBG(2, "msg %p: Reserved %zu (%zu) bytes, pad=%d, nlmsg_len=%d\n",
00562                   n, tlen, len, pad, n->nm_nlh->nlmsg_len);
00563 
00564         return buf;
00565 }
00566 
00567 /**
00568  * Append data to tail of a netlink message
00569  * @arg n               netlink message
00570  * @arg data            data to add
00571  * @arg len             length of data
00572  * @arg pad             Number of bytes to align data to.
00573  *
00574  * Extends the netlink message as needed and appends the data of given
00575  * length to the message. 
00576  *
00577  * @return 0 on success or a negative error code
00578  */
00579 int nlmsg_append(struct nl_msg *n, void *data, size_t len, int pad)
00580 {
00581         void *tmp;
00582 
00583         tmp = nlmsg_reserve(n, len, pad);
00584         if (tmp == NULL)
00585                 return -NLE_NOMEM;
00586 
00587         memcpy(tmp, data, len);
00588         NL_DBG(2, "msg %p: Appended %zu bytes with padding %d\n", n, len, pad);
00589 
00590         return 0;
00591 }
00592 
00593 /**
00594  * Expand maximum payload size of a netlink message
00595  * @arg n               Netlink message.
00596  * @arg newlen          New maximum payload size.
00597  *
00598  * Reallocates the payload section of a netlink message and increases
00599  * the maximum payload size of the message.
00600  *
00601  * @note Any pointers pointing to old payload block will be stale and
00602  *       need to be refetched. Therfore, do not expand while constructing
00603  *       nested attributes or while reserved data blocks are held.
00604  *
00605  * @return 0 on success or a negative error code.
00606  */
00607 int nlmsg_expand(struct nl_msg *n, size_t newlen)
00608 {
00609         void *tmp;
00610 
00611         if (newlen <= n->nm_size)
00612                 return -NLE_INVAL;
00613 
00614         tmp = realloc(n->nm_nlh, newlen);
00615         if (tmp == NULL)
00616                 return -NLE_NOMEM;
00617 
00618         n->nm_nlh = tmp;
00619         n->nm_size = newlen;
00620 
00621         return 0;
00622 }
00623 
00624 /**
00625  * Add a netlink message header to a netlink message
00626  * @arg n               netlink message
00627  * @arg pid             netlink process id or NL_AUTO_PID
00628  * @arg seq             sequence number of message or NL_AUTO_SEQ
00629  * @arg type            message type
00630  * @arg payload         length of message payload
00631  * @arg flags           message flags
00632  *
00633  * Adds or overwrites the netlink message header in an existing message
00634  * object. If \a payload is greater-than zero additional room will be
00635  * reserved, f.e. for family specific headers. It can be accesed via
00636  * nlmsg_data().
00637  *
00638  * @return A pointer to the netlink message header or NULL.
00639  */
00640 struct nlmsghdr *nlmsg_put(struct nl_msg *n, uint32_t pid, uint32_t seq,
00641                            int type, int payload, int flags)
00642 {
00643         struct nlmsghdr *nlh;
00644 
00645         if (n->nm_nlh->nlmsg_len < NLMSG_HDRLEN)
00646                 BUG();
00647 
00648         nlh = (struct nlmsghdr *) n->nm_nlh;
00649         nlh->nlmsg_type = type;
00650         nlh->nlmsg_flags = flags;
00651         nlh->nlmsg_pid = pid;
00652         nlh->nlmsg_seq = seq;
00653 
00654         NL_DBG(2, "msg %p: Added netlink header type=%d, flags=%d, pid=%d, "
00655                   "seq=%d\n", n, type, flags, pid, seq);
00656 
00657         if (payload > 0 &&
00658             nlmsg_reserve(n, payload, NLMSG_ALIGNTO) == NULL)
00659                 return NULL;
00660 
00661         return nlh;
00662 }
00663 
00664 /**
00665  * Return actual netlink message
00666  * @arg n               netlink message
00667  * 
00668  * Returns the actual netlink message casted to the type of the netlink
00669  * message header.
00670  * 
00671  * @return A pointer to the netlink message.
00672  */
00673 struct nlmsghdr *nlmsg_hdr(struct nl_msg *n)
00674 {
00675         return n->nm_nlh;
00676 }
00677 
00678 /**
00679  * Acquire a reference on a netlink message
00680  * @arg msg             message to acquire reference from
00681  */
00682 void nlmsg_get(struct nl_msg *msg)
00683 {
00684         msg->nm_refcnt++;
00685         NL_DBG(4, "New reference to message %p, total %d\n",
00686                msg, msg->nm_refcnt);
00687 }
00688 
00689 /**
00690  * Release a reference from an netlink message
00691  * @arg msg             message to release reference from
00692  *
00693  * Frees memory after the last reference has been released.
00694  */
00695 void nlmsg_free(struct nl_msg *msg)
00696 {
00697         if (!msg)
00698                 return;
00699 
00700         msg->nm_refcnt--;
00701         NL_DBG(4, "Returned message reference %p, %d remaining\n",
00702                msg, msg->nm_refcnt);
00703 
00704         if (msg->nm_refcnt < 0)
00705                 BUG();
00706 
00707         if (msg->nm_refcnt <= 0) {
00708                 free(msg->nm_nlh);
00709                 free(msg);
00710                 NL_DBG(2, "msg %p: Freed\n", msg);
00711         }
00712 }
00713 
00714 /** @} */
00715 
00716 /**
00717  * @name Attributes
00718  * @{
00719  */
00720 
00721 void nlmsg_set_proto(struct nl_msg *msg, int protocol)
00722 {
00723         msg->nm_protocol = protocol;
00724 }
00725 
00726 int nlmsg_get_proto(struct nl_msg *msg)
00727 {
00728         return msg->nm_protocol;
00729 }
00730 
00731 size_t nlmsg_get_max_size(struct nl_msg *msg)
00732 {
00733         return msg->nm_size;
00734 }
00735 
00736 void nlmsg_set_src(struct nl_msg *msg, struct sockaddr_nl *addr)
00737 {
00738         memcpy(&msg->nm_src, addr, sizeof(*addr));
00739 }
00740 
00741 struct sockaddr_nl *nlmsg_get_src(struct nl_msg *msg)
00742 {
00743         return &msg->nm_src;
00744 }
00745 
00746 void nlmsg_set_dst(struct nl_msg *msg, struct sockaddr_nl *addr)
00747 {
00748         memcpy(&msg->nm_dst, addr, sizeof(*addr));
00749 }
00750 
00751 struct sockaddr_nl *nlmsg_get_dst(struct nl_msg *msg)
00752 {
00753         return &msg->nm_dst;
00754 }
00755 
00756 void nlmsg_set_creds(struct nl_msg *msg, struct ucred *creds)
00757 {
00758         memcpy(&msg->nm_creds, creds, sizeof(*creds));
00759         msg->nm_flags |= NL_MSG_CRED_PRESENT;
00760 }
00761 
00762 struct ucred *nlmsg_get_creds(struct nl_msg *msg)
00763 {
00764         if (msg->nm_flags & NL_MSG_CRED_PRESENT)
00765                 return &msg->nm_creds;
00766         return NULL;
00767 }
00768 
00769 /** @} */
00770 
00771 /**
00772  * @name Netlink Message Type Translations
00773  * @{
00774  */
00775 
00776 static const struct trans_tbl nl_msgtypes[] = {
00777         __ADD(NLMSG_NOOP,NOOP)
00778         __ADD(NLMSG_ERROR,ERROR)
00779         __ADD(NLMSG_DONE,DONE)
00780         __ADD(NLMSG_OVERRUN,OVERRUN)
00781 };
00782 
00783 char *nl_nlmsgtype2str(int type, char *buf, size_t size)
00784 {
00785         return __type2str(type, buf, size, nl_msgtypes,
00786                           ARRAY_SIZE(nl_msgtypes));
00787 }
00788 
00789 int nl_str2nlmsgtype(const char *name)
00790 {
00791         return __str2type(name, nl_msgtypes, ARRAY_SIZE(nl_msgtypes));
00792 }
00793 
00794 /** @} */
00795 
00796 /**
00797  * @name Netlink Message Flags Translations
00798  * @{
00799  */
00800 
00801 char *nl_nlmsg_flags2str(int flags, char *buf, size_t len)
00802 {
00803         memset(buf, 0, len);
00804 
00805 #define PRINT_FLAG(f) \
00806         if (flags & NLM_F_##f) { \
00807                 flags &= ~NLM_F_##f; \
00808                 strncat(buf, #f, len - strlen(buf) - 1); \
00809                 if (flags) \
00810                         strncat(buf, ",", len - strlen(buf) - 1); \
00811         }
00812         
00813         PRINT_FLAG(REQUEST);
00814         PRINT_FLAG(MULTI);
00815         PRINT_FLAG(ACK);
00816         PRINT_FLAG(ECHO);
00817         PRINT_FLAG(ROOT);
00818         PRINT_FLAG(MATCH);
00819         PRINT_FLAG(ATOMIC);
00820         PRINT_FLAG(REPLACE);
00821         PRINT_FLAG(EXCL);
00822         PRINT_FLAG(CREATE);
00823         PRINT_FLAG(APPEND);
00824 
00825         if (flags) {
00826                 char s[32];
00827                 snprintf(s, sizeof(s), "0x%x", flags);
00828                 strncat(buf, s, len - strlen(buf) - 1);
00829         }
00830 #undef PRINT_FLAG
00831 
00832         return buf;
00833 }
00834 
00835 /** @} */
00836 
00837 /**
00838  * @name Direct Parsing
00839  * @{
00840  */
00841 
00842 /** @cond SKIP */
00843 struct dp_xdata {
00844         void (*cb)(struct nl_object *, void *);
00845         void *arg;
00846 };
00847 /** @endcond */
00848 
00849 static int parse_cb(struct nl_object *obj, struct nl_parser_param *p)
00850 {
00851         struct dp_xdata *x = p->pp_arg;
00852 
00853         x->cb(obj, x->arg);
00854         return 0;
00855 }
00856 
00857 int nl_msg_parse(struct nl_msg *msg, void (*cb)(struct nl_object *, void *),
00858                  void *arg)
00859 {
00860         struct nl_cache_ops *ops;
00861         struct nl_parser_param p = {
00862                 .pp_cb = parse_cb
00863         };
00864         struct dp_xdata x = {
00865                 .cb = cb,
00866                 .arg = arg,
00867         };
00868 
00869         ops = nl_cache_ops_associate(nlmsg_get_proto(msg),
00870                                      nlmsg_hdr(msg)->nlmsg_type);
00871         if (ops == NULL)
00872                 return -NLE_MSGTYPE_NOSUPPORT;
00873         p.pp_arg = &x;
00874 
00875         return nl_cache_parse(ops, NULL, nlmsg_hdr(msg), &p);
00876 }
00877 
00878 /** @} */
00879 
00880 /**
00881  * @name Dumping
00882  * @{
00883  */
00884 
00885 static void prefix_line(FILE *ofd, int prefix)
00886 {
00887         int i;
00888 
00889         for (i = 0; i < prefix; i++)
00890                 fprintf(ofd, "  ");
00891 }
00892 
00893 static inline void dump_hex(FILE *ofd, char *start, int len, int prefix)
00894 {
00895         int i, a, c, limit;
00896         char ascii[21] = {0};
00897 
00898         limit = 18 - (prefix * 2);
00899         prefix_line(ofd, prefix);
00900         fprintf(ofd, "    ");
00901 
00902         for (i = 0, a = 0, c = 0; i < len; i++) {
00903                 int v = *(uint8_t *) (start + i);
00904 
00905                 fprintf(ofd, "%02x ", v);
00906                 ascii[a++] = isprint(v) ? v : '.';
00907 
00908                 if (c == limit-1) {
00909                         fprintf(ofd, "%s\n", ascii);
00910                         if (i < (len - 1)) {
00911                                 prefix_line(ofd, prefix);
00912                                 fprintf(ofd, "    ");
00913                         }
00914                         a = c = 0;
00915                         memset(ascii, 0, sizeof(ascii));
00916                 } else
00917                         c++;
00918         }
00919 
00920         if (c != 0) {
00921                 for (i = 0; i < (limit - c); i++)
00922                         fprintf(ofd, "   ");
00923                 fprintf(ofd, "%s\n", ascii);
00924         }
00925 }
00926 
00927 static void print_hdr(FILE *ofd, struct nl_msg *msg)
00928 {
00929         struct nlmsghdr *nlh = nlmsg_hdr(msg);
00930         struct nl_cache_ops *ops;
00931         struct nl_msgtype *mt;
00932         char buf[128];
00933 
00934         fprintf(ofd, "    .nlmsg_len = %d\n", nlh->nlmsg_len);
00935 
00936         ops = nl_cache_ops_associate(nlmsg_get_proto(msg), nlh->nlmsg_type);
00937         if (ops) {
00938                 mt = nl_msgtype_lookup(ops, nlh->nlmsg_type);
00939                 if (!mt)
00940                         BUG();
00941 
00942                 snprintf(buf, sizeof(buf), "%s::%s", ops->co_name, mt->mt_name);
00943         } else
00944                 nl_nlmsgtype2str(nlh->nlmsg_type, buf, sizeof(buf));
00945 
00946         fprintf(ofd, "    .nlmsg_type = %d <%s>\n", nlh->nlmsg_type, buf);
00947         fprintf(ofd, "    .nlmsg_flags = %d <%s>\n", nlh->nlmsg_flags,
00948                 nl_nlmsg_flags2str(nlh->nlmsg_flags, buf, sizeof(buf)));
00949         fprintf(ofd, "    .nlmsg_seq = %d\n", nlh->nlmsg_seq);
00950         fprintf(ofd, "    .nlmsg_pid = %d\n", nlh->nlmsg_pid);
00951 
00952 }
00953 
00954 static void dump_attrs(FILE *ofd, struct nlattr *attrs, int attrlen,
00955                        int prefix)
00956 {
00957         int rem;
00958         struct nlattr *nla;
00959 
00960         nla_for_each_attr(nla, attrs, attrlen, rem) {
00961                 int padlen, alen = nla_len(nla);
00962 
00963                 prefix_line(ofd, prefix);
00964                 fprintf(ofd, "  [ATTR %02d%s] %d octets\n", nla_type(nla),
00965                         nla->nla_type & NLA_F_NESTED ? " NESTED" : "",
00966                         alen);
00967 
00968                 if (nla->nla_type & NLA_F_NESTED)
00969                         dump_attrs(ofd, nla_data(nla), alen, prefix+1);
00970                 else
00971                         dump_hex(ofd, nla_data(nla), alen, prefix);
00972 
00973                 padlen = nla_padlen(alen);
00974                 if (padlen > 0) {
00975                         prefix_line(ofd, prefix);
00976                         fprintf(ofd, "  [PADDING] %d octets\n",
00977                                 padlen);
00978                         dump_hex(ofd, nla_data(nla) + alen,
00979                                  padlen, prefix);
00980                 }
00981         }
00982 
00983         if (rem) {
00984                 prefix_line(ofd, prefix);
00985                 fprintf(ofd, "  [LEFTOVER] %d octets\n", rem);
00986         }
00987 }
00988 
00989 /**
00990  * Dump message in human readable format to file descriptor
00991  * @arg msg             Message to print
00992  * @arg ofd             File descriptor.
00993  */
00994 void nl_msg_dump(struct nl_msg *msg, FILE *ofd)
00995 {
00996         struct nlmsghdr *hdr = nlmsg_hdr(msg);
00997         
00998         fprintf(ofd, 
00999         "--------------------------   BEGIN NETLINK MESSAGE "
01000         "---------------------------\n");
01001 
01002         fprintf(ofd, "  [HEADER] %Zu octets\n", sizeof(struct nlmsghdr));
01003         print_hdr(ofd, msg);
01004 
01005         if (hdr->nlmsg_type == NLMSG_ERROR &&
01006             hdr->nlmsg_len >= nlmsg_msg_size(sizeof(struct nlmsgerr))) {
01007                 struct nl_msg *errmsg;
01008                 struct nlmsgerr *err = nlmsg_data(hdr);
01009 
01010                 fprintf(ofd, "  [ERRORMSG] %Zu octets\n", sizeof(*err));
01011                 fprintf(ofd, "    .error = %d \"%s\"\n", err->error,
01012                         strerror(-err->error));
01013                 fprintf(ofd, "  [ORIGINAL MESSAGE] %Zu octets\n", sizeof(*hdr));
01014 
01015                 errmsg = nlmsg_inherit(&err->msg);
01016                 print_hdr(ofd, errmsg);
01017                 nlmsg_free(errmsg);
01018         } else if (nlmsg_len(hdr) > 0) {
01019                 struct nl_cache_ops *ops;
01020                 int payloadlen = nlmsg_len(hdr);
01021                 int attrlen = 0;
01022 
01023                 ops = nl_cache_ops_associate(nlmsg_get_proto(msg),
01024                                              hdr->nlmsg_type);
01025                 if (ops) {
01026                         attrlen = nlmsg_attrlen(hdr, ops->co_hdrsize);
01027                         payloadlen -= attrlen;
01028                 }
01029 
01030                 fprintf(ofd, "  [PAYLOAD] %d octets\n", payloadlen);
01031                 dump_hex(ofd, nlmsg_data(hdr), payloadlen, 0);
01032 
01033                 if (attrlen) {
01034                         struct nlattr *attrs;
01035                         int attrlen;
01036                         
01037                         attrs = nlmsg_attrdata(hdr, ops->co_hdrsize);
01038                         attrlen = nlmsg_attrlen(hdr, ops->co_hdrsize);
01039                         dump_attrs(ofd, attrs, attrlen, 0);
01040                 }
01041         }
01042 
01043         fprintf(ofd, 
01044         "---------------------------  END NETLINK MESSAGE   "
01045         "---------------------------\n");
01046 }
01047 
01048 /** @} */
01049 
01050 /** @} */