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  * Calculates size of netlink message based on payload length.
00182  * @arg payload         Length of payload
00183  *
00184  * See \ref core_msg_fmt_align for more information on alignment.
00185  *
00186  * @return size of netlink message without padding.
00187  */
00188 int nlmsg_size(int payload)
00189 {
00190         return NLMSG_HDRLEN + payload;
00191 }
00192 
00193 int nlmsg_msg_size(int payload)
00194 {
00195         return nlmsg_size(payload);
00196 }
00197 
00198 /**
00199  * Calculates size of netlink message including padding based on payload length
00200  * @arg payload         Length of payload
00201  *
00202  * This function is idential to nlmsg_size() + nlmsg_padlen().
00203  *
00204  * See \ref core_msg_fmt_align for more information on alignment.
00205  *
00206  * @return Size of netlink message including padding.
00207  */
00208 int nlmsg_total_size(int payload)
00209 {
00210         return NLMSG_ALIGN(nlmsg_msg_size(payload));
00211 }
00212 
00213 /**
00214  * Size of padding that needs to be added at end of message
00215  * @arg payload         Length of payload
00216  *
00217  * Calculates the number of bytes of padding which is required to be added to
00218  * the end of the message to ensure that the next netlink message header begins
00219  * properly aligned to NLMSG_ALIGNTO.
00220  *
00221  * See \ref core_msg_fmt_align for more information on alignment.
00222  *
00223  * @return Number of bytes of padding needed.
00224  */
00225 int nlmsg_padlen(int payload)
00226 {
00227         return nlmsg_total_size(payload) - nlmsg_msg_size(payload);
00228 }
00229 
00230 /** @} */
00231 
00232 /**
00233  * @name Access to Message Payload
00234  * @{
00235  */
00236 
00237 /**
00238  * Return pointer to message payload
00239  * @arg nlh             Netlink message header
00240  *
00241  * @return Pointer to start of message payload.
00242  */
00243 void *nlmsg_data(const struct nlmsghdr *nlh)
00244 {
00245         return (unsigned char *) nlh + NLMSG_HDRLEN;
00246 }
00247 
00248 void *nlmsg_tail(const struct nlmsghdr *nlh)
00249 {
00250         return (unsigned char *) nlh + NLMSG_ALIGN(nlh->nlmsg_len);
00251 }
00252 
00253 /**
00254  * Return length of message payload
00255  * @arg nlh             Netlink message header
00256  *
00257  * @return Length of message payload in bytes.
00258  */
00259 int nlmsg_datalen(const struct nlmsghdr *nlh)
00260 {
00261         return nlh->nlmsg_len - NLMSG_HDRLEN;
00262 }
00263 
00264 int nlmsg_len(const struct nlmsghdr *nlh)
00265 {
00266         return nlmsg_datalen(nlh);
00267 }
00268 
00269 /** @} */
00270 
00271 /**
00272  * @name Attribute Access
00273  * @{
00274  */
00275 
00276 /**
00277  * head of attributes data
00278  * @arg nlh             netlink message header
00279  * @arg hdrlen          length of family specific header
00280  */
00281 struct nlattr *nlmsg_attrdata(const struct nlmsghdr *nlh, int hdrlen)
00282 {
00283         unsigned char *data = nlmsg_data(nlh);
00284         return (struct nlattr *) (data + NLMSG_ALIGN(hdrlen));
00285 }
00286 
00287 /**
00288  * length of attributes data
00289  * @arg nlh             netlink message header
00290  * @arg hdrlen          length of family specific header
00291  */
00292 int nlmsg_attrlen(const struct nlmsghdr *nlh, int hdrlen)
00293 {
00294         return nlmsg_len(nlh) - NLMSG_ALIGN(hdrlen);
00295 }
00296 
00297 /** @} */
00298 
00299 /**
00300  * @name Message Parsing
00301  * @{
00302  */
00303 
00304 int nlmsg_valid_hdr(const struct nlmsghdr *nlh, int hdrlen)
00305 {
00306         if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
00307                 return 0;
00308 
00309         return 1;
00310 }
00311 
00312 /**
00313  * check if the netlink message fits into the remaining bytes
00314  * @arg nlh             netlink message header
00315  * @arg remaining       number of bytes remaining in message stream
00316  */
00317 int nlmsg_ok(const struct nlmsghdr *nlh, int remaining)
00318 {
00319         return (remaining >= (int)sizeof(struct nlmsghdr) &&
00320                 nlh->nlmsg_len >= sizeof(struct nlmsghdr) &&
00321                 nlh->nlmsg_len <= remaining);
00322 }
00323 
00324 /**
00325  * next netlink message in message stream
00326  * @arg nlh             netlink message header
00327  * @arg remaining       number of bytes remaining in message stream
00328  *
00329  * @returns the next netlink message in the message stream and
00330  * decrements remaining by the size of the current message.
00331  */
00332 struct nlmsghdr *nlmsg_next(struct nlmsghdr *nlh, int *remaining)
00333 {
00334         int totlen = NLMSG_ALIGN(nlh->nlmsg_len);
00335 
00336         *remaining -= totlen;
00337 
00338         return (struct nlmsghdr *) ((unsigned char *) nlh + totlen);
00339 }
00340 
00341 /**
00342  * parse attributes of a netlink message
00343  * @arg nlh             netlink message header
00344  * @arg hdrlen          length of family specific header
00345  * @arg tb              destination array with maxtype+1 elements
00346  * @arg maxtype         maximum attribute type to be expected
00347  * @arg policy          validation policy
00348  *
00349  * See nla_parse()
00350  */
00351 int nlmsg_parse(struct nlmsghdr *nlh, int hdrlen, struct nlattr *tb[],
00352                 int maxtype, struct nla_policy *policy)
00353 {
00354         if (!nlmsg_valid_hdr(nlh, hdrlen))
00355                 return -NLE_MSG_TOOSHORT;
00356 
00357         return nla_parse(tb, maxtype, nlmsg_attrdata(nlh, hdrlen),
00358                          nlmsg_attrlen(nlh, hdrlen), policy);
00359 }
00360 
00361 /**
00362  * nlmsg_find_attr - find a specific attribute in a netlink message
00363  * @arg nlh             netlink message header
00364  * @arg hdrlen          length of familiy specific header
00365  * @arg attrtype        type of attribute to look for
00366  *
00367  * Returns the first attribute which matches the specified type.
00368  */
00369 struct nlattr *nlmsg_find_attr(struct nlmsghdr *nlh, int hdrlen, int attrtype)
00370 {
00371         return nla_find(nlmsg_attrdata(nlh, hdrlen),
00372                         nlmsg_attrlen(nlh, hdrlen), attrtype);
00373 }
00374 
00375 /**
00376  * nlmsg_validate - validate a netlink message including attributes
00377  * @arg nlh             netlinket message header
00378  * @arg hdrlen          length of familiy specific header
00379  * @arg maxtype         maximum attribute type to be expected
00380  * @arg policy          validation policy
00381  */
00382 int nlmsg_validate(struct nlmsghdr *nlh, int hdrlen, int maxtype,
00383                    struct nla_policy *policy)
00384 {
00385         if (!nlmsg_valid_hdr(nlh, hdrlen))
00386                 return -NLE_MSG_TOOSHORT;
00387 
00388         return nla_validate(nlmsg_attrdata(nlh, hdrlen),
00389                             nlmsg_attrlen(nlh, hdrlen), maxtype, policy);
00390 }
00391 
00392 /** @} */
00393 
00394 /**
00395  * @name Message Building/Access
00396  * @{
00397  */
00398 
00399 static struct nl_msg *__nlmsg_alloc(size_t len)
00400 {
00401         struct nl_msg *nm;
00402 
00403         if (len < sizeof(struct nlmsghdr))
00404                 len = sizeof(struct nlmsghdr);
00405 
00406         nm = calloc(1, sizeof(*nm));
00407         if (!nm)
00408                 goto errout;
00409 
00410         nm->nm_refcnt = 1;
00411 
00412         nm->nm_nlh = calloc(1, len);
00413         if (!nm->nm_nlh)
00414                 goto errout;
00415 
00416         memset(nm->nm_nlh, 0, sizeof(struct nlmsghdr));
00417 
00418         nm->nm_protocol = -1;
00419         nm->nm_size = len;
00420         nm->nm_nlh->nlmsg_len = nlmsg_total_size(0);
00421 
00422         NL_DBG(2, "msg %p: Allocated new message, maxlen=%zu\n", nm, len);
00423 
00424         return nm;
00425 errout:
00426         free(nm);
00427         return NULL;
00428 }
00429 
00430 /**
00431  * Allocate a new netlink message with the default maximum payload size.
00432  *
00433  * Allocates a new netlink message without any further payload. The
00434  * maximum payload size defaults to PAGESIZE or as otherwise specified
00435  * with nlmsg_set_default_size().
00436  *
00437  * @return Newly allocated netlink message or NULL.
00438  */
00439 struct nl_msg *nlmsg_alloc(void)
00440 {
00441         return __nlmsg_alloc(default_msg_size);
00442 }
00443 
00444 /**
00445  * Allocate a new netlink message with maximum payload size specified.
00446  */
00447 struct nl_msg *nlmsg_alloc_size(size_t max)
00448 {
00449         return __nlmsg_alloc(max);
00450 }
00451 
00452 /**
00453  * Allocate a new netlink message and inherit netlink message header
00454  * @arg hdr             Netlink message header template
00455  *
00456  * Allocates a new netlink message and inherits the original message
00457  * header. If \a hdr is not NULL it will be used as a template for
00458  * the netlink message header, otherwise the header is left blank.
00459  * 
00460  * @return Newly allocated netlink message or NULL
00461  */ 
00462 struct nl_msg *nlmsg_inherit(struct nlmsghdr *hdr)
00463 {
00464         struct nl_msg *nm;
00465 
00466         nm = nlmsg_alloc();
00467         if (nm && hdr) {
00468                 struct nlmsghdr *new = nm->nm_nlh;
00469 
00470                 new->nlmsg_type = hdr->nlmsg_type;
00471                 new->nlmsg_flags = hdr->nlmsg_flags;
00472                 new->nlmsg_seq = hdr->nlmsg_seq;
00473                 new->nlmsg_pid = hdr->nlmsg_pid;
00474         }
00475 
00476         return nm;
00477 }
00478 
00479 /**
00480  * Allocate a new netlink message
00481  * @arg nlmsgtype       Netlink message type
00482  * @arg flags           Message flags.
00483  *
00484  * @return Newly allocated netlink message or NULL.
00485  */
00486 struct nl_msg *nlmsg_alloc_simple(int nlmsgtype, int flags)
00487 {
00488         struct nl_msg *msg;
00489         struct nlmsghdr nlh = {
00490                 .nlmsg_type = nlmsgtype,
00491                 .nlmsg_flags = flags,
00492         };
00493 
00494         msg = nlmsg_inherit(&nlh);
00495         if (msg)
00496                 NL_DBG(2, "msg %p: Allocated new simple message\n", msg);
00497 
00498         return msg;
00499 }
00500 
00501 /**
00502  * Set the default maximum message payload size for allocated messages
00503  * @arg max             Size of payload in bytes.
00504  */
00505 void nlmsg_set_default_size(size_t max)
00506 {
00507         if (max < nlmsg_total_size(0))
00508                 max = nlmsg_total_size(0);
00509 
00510         default_msg_size = max;
00511 }
00512 
00513 /**
00514  * Convert a netlink message received from a netlink socket to a nl_msg
00515  * @arg hdr             Netlink message received from netlink socket.
00516  *
00517  * Allocates a new netlink message and copies all of the data pointed to
00518  * by \a hdr into the new message object.
00519  *
00520  * @return Newly allocated netlink message or NULL.
00521  */
00522 struct nl_msg *nlmsg_convert(struct nlmsghdr *hdr)
00523 {
00524         struct nl_msg *nm;
00525 
00526         nm = __nlmsg_alloc(NLMSG_ALIGN(hdr->nlmsg_len));
00527         if (!nm)
00528                 goto errout;
00529 
00530         memcpy(nm->nm_nlh, hdr, hdr->nlmsg_len);
00531 
00532         return nm;
00533 errout:
00534         nlmsg_free(nm);
00535         return NULL;
00536 }
00537 
00538 /**
00539  * Reserve room for additional data in a netlink message
00540  * @arg n               netlink message
00541  * @arg len             length of additional data to reserve room for
00542  * @arg pad             number of bytes to align data to
00543  *
00544  * Reserves room for additional data at the tail of the an
00545  * existing netlink message. Eventual padding required will
00546  * be zeroed out.
00547  *
00548  * @return Pointer to start of additional data tailroom or NULL.
00549  */
00550 void *nlmsg_reserve(struct nl_msg *n, size_t len, int pad)
00551 {
00552         void *buf = n->nm_nlh;
00553         size_t nlmsg_len = n->nm_nlh->nlmsg_len;
00554         size_t tlen;
00555 
00556         tlen = pad ? ((len + (pad - 1)) & ~(pad - 1)) : len;
00557 
00558         if ((tlen + nlmsg_len) > n->nm_size)
00559                 return NULL;
00560 
00561         buf += nlmsg_len;
00562         n->nm_nlh->nlmsg_len += tlen;
00563 
00564         if (tlen > len)
00565                 memset(buf + len, 0, tlen - len);
00566 
00567         NL_DBG(2, "msg %p: Reserved %zu (%zu) bytes, pad=%d, nlmsg_len=%d\n",
00568                   n, tlen, len, pad, n->nm_nlh->nlmsg_len);
00569 
00570         return buf;
00571 }
00572 
00573 /**
00574  * Append data to tail of a netlink message
00575  * @arg n               netlink message
00576  * @arg data            data to add
00577  * @arg len             length of data
00578  * @arg pad             Number of bytes to align data to.
00579  *
00580  * Extends the netlink message as needed and appends the data of given
00581  * length to the message. 
00582  *
00583  * @return 0 on success or a negative error code
00584  */
00585 int nlmsg_append(struct nl_msg *n, void *data, size_t len, int pad)
00586 {
00587         void *tmp;
00588 
00589         tmp = nlmsg_reserve(n, len, pad);
00590         if (tmp == NULL)
00591                 return -NLE_NOMEM;
00592 
00593         memcpy(tmp, data, len);
00594         NL_DBG(2, "msg %p: Appended %zu bytes with padding %d\n", n, len, pad);
00595 
00596         return 0;
00597 }
00598 
00599 /**
00600  * Expand maximum payload size of a netlink message
00601  * @arg n               Netlink message.
00602  * @arg newlen          New maximum payload size.
00603  *
00604  * Reallocates the payload section of a netlink message and increases
00605  * the maximum payload size of the message.
00606  *
00607  * @note Any pointers pointing to old payload block will be stale and
00608  *       need to be refetched. Therfore, do not expand while constructing
00609  *       nested attributes or while reserved data blocks are held.
00610  *
00611  * @return 0 on success or a negative error code.
00612  */
00613 int nlmsg_expand(struct nl_msg *n, size_t newlen)
00614 {
00615         void *tmp;
00616 
00617         if (newlen <= n->nm_size)
00618                 return -NLE_INVAL;
00619 
00620         tmp = realloc(n->nm_nlh, newlen);
00621         if (tmp == NULL)
00622                 return -NLE_NOMEM;
00623 
00624         n->nm_nlh = tmp;
00625         n->nm_size = newlen;
00626 
00627         return 0;
00628 }
00629 
00630 /**
00631  * Add a netlink message header to a netlink message
00632  * @arg n               netlink message
00633  * @arg pid             netlink process id or NL_AUTO_PID
00634  * @arg seq             sequence number of message or NL_AUTO_SEQ
00635  * @arg type            message type
00636  * @arg payload         length of message payload
00637  * @arg flags           message flags
00638  *
00639  * Adds or overwrites the netlink message header in an existing message
00640  * object. If \a payload is greater-than zero additional room will be
00641  * reserved, f.e. for family specific headers. It can be accesed via
00642  * nlmsg_data().
00643  *
00644  * @return A pointer to the netlink message header or NULL.
00645  */
00646 struct nlmsghdr *nlmsg_put(struct nl_msg *n, uint32_t pid, uint32_t seq,
00647                            int type, int payload, int flags)
00648 {
00649         struct nlmsghdr *nlh;
00650 
00651         if (n->nm_nlh->nlmsg_len < NLMSG_HDRLEN)
00652                 BUG();
00653 
00654         nlh = (struct nlmsghdr *) n->nm_nlh;
00655         nlh->nlmsg_type = type;
00656         nlh->nlmsg_flags = flags;
00657         nlh->nlmsg_pid = pid;
00658         nlh->nlmsg_seq = seq;
00659 
00660         NL_DBG(2, "msg %p: Added netlink header type=%d, flags=%d, pid=%d, "
00661                   "seq=%d\n", n, type, flags, pid, seq);
00662 
00663         if (payload > 0 &&
00664             nlmsg_reserve(n, payload, NLMSG_ALIGNTO) == NULL)
00665                 return NULL;
00666 
00667         return nlh;
00668 }
00669 
00670 /**
00671  * Return actual netlink message
00672  * @arg n               netlink message
00673  * 
00674  * Returns the actual netlink message casted to the type of the netlink
00675  * message header.
00676  * 
00677  * @return A pointer to the netlink message.
00678  */
00679 struct nlmsghdr *nlmsg_hdr(struct nl_msg *n)
00680 {
00681         return n->nm_nlh;
00682 }
00683 
00684 /**
00685  * Acquire a reference on a netlink message
00686  * @arg msg             message to acquire reference from
00687  */
00688 void nlmsg_get(struct nl_msg *msg)
00689 {
00690         msg->nm_refcnt++;
00691         NL_DBG(4, "New reference to message %p, total %d\n",
00692                msg, msg->nm_refcnt);
00693 }
00694 
00695 /**
00696  * Release a reference from an netlink message
00697  * @arg msg             message to release reference from
00698  *
00699  * Frees memory after the last reference has been released.
00700  */
00701 void nlmsg_free(struct nl_msg *msg)
00702 {
00703         if (!msg)
00704                 return;
00705 
00706         msg->nm_refcnt--;
00707         NL_DBG(4, "Returned message reference %p, %d remaining\n",
00708                msg, msg->nm_refcnt);
00709 
00710         if (msg->nm_refcnt < 0)
00711                 BUG();
00712 
00713         if (msg->nm_refcnt <= 0) {
00714                 free(msg->nm_nlh);
00715                 free(msg);
00716                 NL_DBG(2, "msg %p: Freed\n", msg);
00717         }
00718 }
00719 
00720 /** @} */
00721 
00722 /**
00723  * @name Attributes
00724  * @{
00725  */
00726 
00727 void nlmsg_set_proto(struct nl_msg *msg, int protocol)
00728 {
00729         msg->nm_protocol = protocol;
00730 }
00731 
00732 int nlmsg_get_proto(struct nl_msg *msg)
00733 {
00734         return msg->nm_protocol;
00735 }
00736 
00737 size_t nlmsg_get_max_size(struct nl_msg *msg)
00738 {
00739         return msg->nm_size;
00740 }
00741 
00742 void nlmsg_set_src(struct nl_msg *msg, struct sockaddr_nl *addr)
00743 {
00744         memcpy(&msg->nm_src, addr, sizeof(*addr));
00745 }
00746 
00747 struct sockaddr_nl *nlmsg_get_src(struct nl_msg *msg)
00748 {
00749         return &msg->nm_src;
00750 }
00751 
00752 void nlmsg_set_dst(struct nl_msg *msg, struct sockaddr_nl *addr)
00753 {
00754         memcpy(&msg->nm_dst, addr, sizeof(*addr));
00755 }
00756 
00757 struct sockaddr_nl *nlmsg_get_dst(struct nl_msg *msg)
00758 {
00759         return &msg->nm_dst;
00760 }
00761 
00762 void nlmsg_set_creds(struct nl_msg *msg, struct ucred *creds)
00763 {
00764         memcpy(&msg->nm_creds, creds, sizeof(*creds));
00765         msg->nm_flags |= NL_MSG_CRED_PRESENT;
00766 }
00767 
00768 struct ucred *nlmsg_get_creds(struct nl_msg *msg)
00769 {
00770         if (msg->nm_flags & NL_MSG_CRED_PRESENT)
00771                 return &msg->nm_creds;
00772         return NULL;
00773 }
00774 
00775 /** @} */
00776 
00777 /**
00778  * @name Netlink Message Type Translations
00779  * @{
00780  */
00781 
00782 static const struct trans_tbl nl_msgtypes[] = {
00783         __ADD(NLMSG_NOOP,NOOP)
00784         __ADD(NLMSG_ERROR,ERROR)
00785         __ADD(NLMSG_DONE,DONE)
00786         __ADD(NLMSG_OVERRUN,OVERRUN)
00787 };
00788 
00789 char *nl_nlmsgtype2str(int type, char *buf, size_t size)
00790 {
00791         return __type2str(type, buf, size, nl_msgtypes,
00792                           ARRAY_SIZE(nl_msgtypes));
00793 }
00794 
00795 int nl_str2nlmsgtype(const char *name)
00796 {
00797         return __str2type(name, nl_msgtypes, ARRAY_SIZE(nl_msgtypes));
00798 }
00799 
00800 /** @} */
00801 
00802 /**
00803  * @name Netlink Message Flags Translations
00804  * @{
00805  */
00806 
00807 char *nl_nlmsg_flags2str(int flags, char *buf, size_t len)
00808 {
00809         memset(buf, 0, len);
00810 
00811 #define PRINT_FLAG(f) \
00812         if (flags & NLM_F_##f) { \
00813                 flags &= ~NLM_F_##f; \
00814                 strncat(buf, #f, len - strlen(buf) - 1); \
00815                 if (flags) \
00816                         strncat(buf, ",", len - strlen(buf) - 1); \
00817         }
00818         
00819         PRINT_FLAG(REQUEST);
00820         PRINT_FLAG(MULTI);
00821         PRINT_FLAG(ACK);
00822         PRINT_FLAG(ECHO);
00823         PRINT_FLAG(ROOT);
00824         PRINT_FLAG(MATCH);
00825         PRINT_FLAG(ATOMIC);
00826         PRINT_FLAG(REPLACE);
00827         PRINT_FLAG(EXCL);
00828         PRINT_FLAG(CREATE);
00829         PRINT_FLAG(APPEND);
00830 
00831         if (flags) {
00832                 char s[32];
00833                 snprintf(s, sizeof(s), "0x%x", flags);
00834                 strncat(buf, s, len - strlen(buf) - 1);
00835         }
00836 #undef PRINT_FLAG
00837 
00838         return buf;
00839 }
00840 
00841 /** @} */
00842 
00843 /**
00844  * @name Direct Parsing
00845  * @{
00846  */
00847 
00848 /** @cond SKIP */
00849 struct dp_xdata {
00850         void (*cb)(struct nl_object *, void *);
00851         void *arg;
00852 };
00853 /** @endcond */
00854 
00855 static int parse_cb(struct nl_object *obj, struct nl_parser_param *p)
00856 {
00857         struct dp_xdata *x = p->pp_arg;
00858 
00859         x->cb(obj, x->arg);
00860         return 0;
00861 }
00862 
00863 int nl_msg_parse(struct nl_msg *msg, void (*cb)(struct nl_object *, void *),
00864                  void *arg)
00865 {
00866         struct nl_cache_ops *ops;
00867         struct nl_parser_param p = {
00868                 .pp_cb = parse_cb
00869         };
00870         struct dp_xdata x = {
00871                 .cb = cb,
00872                 .arg = arg,
00873         };
00874 
00875         ops = nl_cache_ops_associate(nlmsg_get_proto(msg),
00876                                      nlmsg_hdr(msg)->nlmsg_type);
00877         if (ops == NULL)
00878                 return -NLE_MSGTYPE_NOSUPPORT;
00879         p.pp_arg = &x;
00880 
00881         return nl_cache_parse(ops, NULL, nlmsg_hdr(msg), &p);
00882 }
00883 
00884 /** @} */
00885 
00886 /**
00887  * @name Dumping
00888  * @{
00889  */
00890 
00891 static void prefix_line(FILE *ofd, int prefix)
00892 {
00893         int i;
00894 
00895         for (i = 0; i < prefix; i++)
00896                 fprintf(ofd, "  ");
00897 }
00898 
00899 static inline void dump_hex(FILE *ofd, char *start, int len, int prefix)
00900 {
00901         int i, a, c, limit;
00902         char ascii[21] = {0};
00903 
00904         limit = 18 - (prefix * 2);
00905         prefix_line(ofd, prefix);
00906         fprintf(ofd, "    ");
00907 
00908         for (i = 0, a = 0, c = 0; i < len; i++) {
00909                 int v = *(uint8_t *) (start + i);
00910 
00911                 fprintf(ofd, "%02x ", v);
00912                 ascii[a++] = isprint(v) ? v : '.';
00913 
00914                 if (c == limit-1) {
00915                         fprintf(ofd, "%s\n", ascii);
00916                         if (i < (len - 1)) {
00917                                 prefix_line(ofd, prefix);
00918                                 fprintf(ofd, "    ");
00919                         }
00920                         a = c = 0;
00921                         memset(ascii, 0, sizeof(ascii));
00922                 } else
00923                         c++;
00924         }
00925 
00926         if (c != 0) {
00927                 for (i = 0; i < (limit - c); i++)
00928                         fprintf(ofd, "   ");
00929                 fprintf(ofd, "%s\n", ascii);
00930         }
00931 }
00932 
00933 static void print_hdr(FILE *ofd, struct nl_msg *msg)
00934 {
00935         struct nlmsghdr *nlh = nlmsg_hdr(msg);
00936         struct nl_cache_ops *ops;
00937         struct nl_msgtype *mt;
00938         char buf[128];
00939 
00940         fprintf(ofd, "    .nlmsg_len = %d\n", nlh->nlmsg_len);
00941 
00942         ops = nl_cache_ops_associate(nlmsg_get_proto(msg), nlh->nlmsg_type);
00943         if (ops) {
00944                 mt = nl_msgtype_lookup(ops, nlh->nlmsg_type);
00945                 if (!mt)
00946                         BUG();
00947 
00948                 snprintf(buf, sizeof(buf), "%s::%s", ops->co_name, mt->mt_name);
00949         } else
00950                 nl_nlmsgtype2str(nlh->nlmsg_type, buf, sizeof(buf));
00951 
00952         fprintf(ofd, "    .nlmsg_type = %d <%s>\n", nlh->nlmsg_type, buf);
00953         fprintf(ofd, "    .nlmsg_flags = %d <%s>\n", nlh->nlmsg_flags,
00954                 nl_nlmsg_flags2str(nlh->nlmsg_flags, buf, sizeof(buf)));
00955         fprintf(ofd, "    .nlmsg_seq = %d\n", nlh->nlmsg_seq);
00956         fprintf(ofd, "    .nlmsg_pid = %d\n", nlh->nlmsg_pid);
00957 
00958 }
00959 
00960 static void dump_attrs(FILE *ofd, struct nlattr *attrs, int attrlen,
00961                        int prefix)
00962 {
00963         int rem;
00964         struct nlattr *nla;
00965 
00966         nla_for_each_attr(nla, attrs, attrlen, rem) {
00967                 int padlen, alen = nla_len(nla);
00968 
00969                 prefix_line(ofd, prefix);
00970                 fprintf(ofd, "  [ATTR %02d%s] %d octets\n", nla_type(nla),
00971                         nla->nla_type & NLA_F_NESTED ? " NESTED" : "",
00972                         alen);
00973 
00974                 if (nla->nla_type & NLA_F_NESTED)
00975                         dump_attrs(ofd, nla_data(nla), alen, prefix+1);
00976                 else
00977                         dump_hex(ofd, nla_data(nla), alen, prefix);
00978 
00979                 padlen = nla_padlen(alen);
00980                 if (padlen > 0) {
00981                         prefix_line(ofd, prefix);
00982                         fprintf(ofd, "  [PADDING] %d octets\n",
00983                                 padlen);
00984                         dump_hex(ofd, nla_data(nla) + alen,
00985                                  padlen, prefix);
00986                 }
00987         }
00988 
00989         if (rem) {
00990                 prefix_line(ofd, prefix);
00991                 fprintf(ofd, "  [LEFTOVER] %d octets\n", rem);
00992         }
00993 }
00994 
00995 /**
00996  * Dump message in human readable format to file descriptor
00997  * @arg msg             Message to print
00998  * @arg ofd             File descriptor.
00999  */
01000 void nl_msg_dump(struct nl_msg *msg, FILE *ofd)
01001 {
01002         struct nlmsghdr *hdr = nlmsg_hdr(msg);
01003         
01004         fprintf(ofd, 
01005         "--------------------------   BEGIN NETLINK MESSAGE "
01006         "---------------------------\n");
01007 
01008         fprintf(ofd, "  [HEADER] %Zu octets\n", sizeof(struct nlmsghdr));
01009         print_hdr(ofd, msg);
01010 
01011         if (hdr->nlmsg_type == NLMSG_ERROR &&
01012             hdr->nlmsg_len >= nlmsg_msg_size(sizeof(struct nlmsgerr))) {
01013                 struct nl_msg *errmsg;
01014                 struct nlmsgerr *err = nlmsg_data(hdr);
01015 
01016                 fprintf(ofd, "  [ERRORMSG] %Zu octets\n", sizeof(*err));
01017                 fprintf(ofd, "    .error = %d \"%s\"\n", err->error,
01018                         strerror(-err->error));
01019                 fprintf(ofd, "  [ORIGINAL MESSAGE] %Zu octets\n", sizeof(*hdr));
01020 
01021                 errmsg = nlmsg_inherit(&err->msg);
01022                 print_hdr(ofd, errmsg);
01023                 nlmsg_free(errmsg);
01024         } else if (nlmsg_len(hdr) > 0) {
01025                 struct nl_cache_ops *ops;
01026                 int payloadlen = nlmsg_len(hdr);
01027                 int attrlen = 0;
01028 
01029                 ops = nl_cache_ops_associate(nlmsg_get_proto(msg),
01030                                              hdr->nlmsg_type);
01031                 if (ops) {
01032                         attrlen = nlmsg_attrlen(hdr, ops->co_hdrsize);
01033                         payloadlen -= attrlen;
01034                 }
01035 
01036                 fprintf(ofd, "  [PAYLOAD] %d octets\n", payloadlen);
01037                 dump_hex(ofd, nlmsg_data(hdr), payloadlen, 0);
01038 
01039                 if (attrlen) {
01040                         struct nlattr *attrs;
01041                         int attrlen;
01042                         
01043                         attrs = nlmsg_attrdata(hdr, ops->co_hdrsize);
01044                         attrlen = nlmsg_attrlen(hdr, ops->co_hdrsize);
01045                         dump_attrs(ofd, attrs, attrlen, 0);
01046                 }
01047         }
01048 
01049         fprintf(ofd, 
01050         "---------------------------  END NETLINK MESSAGE   "
01051         "---------------------------\n");
01052 }
01053 
01054 /** @} */
01055 
01056 /** @} */