libnl  3.5.0
msg.c
1 /* SPDX-License-Identifier: LGPL-2.1-only */
2 /*
3  * lib/msg.c Netlink Messages Interface
4  *
5  * This library is free software; you can redistribute it and/or
6  * modify it under the terms of the GNU Lesser General Public
7  * License as published by the Free Software Foundation version 2.1
8  * of the License.
9  *
10  * Copyright (c) 2003-2012 Thomas Graf <tgraf@suug.ch>
11  */
12 
13 /**
14  * @ingroup core
15  * @defgroup msg Message Construction & Parsing
16  * Netlink Message Construction/Parsing Interface
17  *
18  * Related sections in the development guide:
19  * - @core_doc{_message_parsing_amp_construction,Message Parsing & Construction}
20  *
21  * @{
22  *
23  * Header
24  * ------
25  * ~~~~{.c}
26  * #include <netlink/msg.h>
27  * ~~~~
28  */
29 
30 #include <netlink-private/netlink.h>
31 #include <netlink-private/utils.h>
32 #include <netlink/netlink.h>
33 #include <netlink/utils.h>
34 #include <netlink/cache.h>
35 #include <netlink/attr.h>
36 #include <linux/socket.h>
37 
38 static size_t default_msg_size;
39 
40 static void __init init_msg_size(void)
41 {
42  default_msg_size = getpagesize();
43 }
44 
45 /**
46  * @name Size Calculations
47  * @{
48  */
49 
50 /**
51  * Calculates size of netlink message based on payload length.
52  * @arg payload Length of payload
53  *
54  * @return size of netlink message without padding.
55  */
56 int nlmsg_size(int payload)
57 {
58  return NLMSG_HDRLEN + payload;
59 }
60 
61 static int nlmsg_msg_size(int payload)
62 {
63  return nlmsg_size(payload);
64 }
65 
66 /**
67  * Calculates size of netlink message including padding based on payload length
68  * @arg payload Length of payload
69  *
70  * This function is idential to nlmsg_size() + nlmsg_padlen().
71  *
72  * @return Size of netlink message including padding.
73  */
74 int nlmsg_total_size(int payload)
75 {
76  return NLMSG_ALIGN(nlmsg_msg_size(payload));
77 }
78 
79 /**
80  * Size of padding that needs to be added at end of message
81  * @arg payload Length of payload
82  *
83  * Calculates the number of bytes of padding which is required to be added to
84  * the end of the message to ensure that the next netlink message header begins
85  * properly aligned to NLMSG_ALIGNTO.
86  *
87  * @return Number of bytes of padding needed.
88  */
89 int nlmsg_padlen(int payload)
90 {
91  return nlmsg_total_size(payload) - nlmsg_msg_size(payload);
92 }
93 
94 /** @} */
95 
96 /**
97  * @name Access to Message Payload
98  * @{
99  */
100 
101 /**
102  * Return pointer to message payload
103  * @arg nlh Netlink message header
104  *
105  * @return Pointer to start of message payload.
106  */
107 void *nlmsg_data(const struct nlmsghdr *nlh)
108 {
109  return (unsigned char *) nlh + NLMSG_HDRLEN;
110 }
111 
112 void *nlmsg_tail(const struct nlmsghdr *nlh)
113 {
114  return (unsigned char *) nlh + NLMSG_ALIGN(nlh->nlmsg_len);
115 }
116 
117 /**
118  * Return length of message payload
119  * @arg nlh Netlink message header
120  *
121  * @return Length of message payload in bytes.
122  */
123 int nlmsg_datalen(const struct nlmsghdr *nlh)
124 {
125  return nlh->nlmsg_len - NLMSG_HDRLEN;
126 }
127 
128 static int nlmsg_len(const struct nlmsghdr *nlh)
129 {
130  return nlmsg_datalen(nlh);
131 }
132 
133 /** @} */
134 
135 /**
136  * @name Attribute Access
137  * @{
138  */
139 
140 /**
141  * head of attributes data
142  * @arg nlh netlink message header
143  * @arg hdrlen length of family specific header
144  */
145 struct nlattr *nlmsg_attrdata(const struct nlmsghdr *nlh, int hdrlen)
146 {
147  unsigned char *data = nlmsg_data(nlh);
148  return (struct nlattr *) (data + NLMSG_ALIGN(hdrlen));
149 }
150 
151 /**
152  * length of attributes data
153  * @arg nlh netlink message header
154  * @arg hdrlen length of family specific header
155  */
156 int nlmsg_attrlen(const struct nlmsghdr *nlh, int hdrlen)
157 {
158  return max_t(int, nlmsg_len(nlh) - NLMSG_ALIGN(hdrlen), 0);
159 }
160 
161 /** @} */
162 
163 /**
164  * @name Message Parsing
165  * @{
166  */
167 
168 int nlmsg_valid_hdr(const struct nlmsghdr *nlh, int hdrlen)
169 {
170  if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
171  return 0;
172 
173  return 1;
174 }
175 
176 /**
177  * check if the netlink message fits into the remaining bytes
178  * @arg nlh netlink message header
179  * @arg remaining number of bytes remaining in message stream
180  */
181 int nlmsg_ok(const struct nlmsghdr *nlh, int remaining)
182 {
183  return (remaining >= (int)sizeof(struct nlmsghdr) &&
184  nlh->nlmsg_len >= sizeof(struct nlmsghdr) &&
185  nlh->nlmsg_len <= remaining);
186 }
187 
188 /**
189  * next netlink message in message stream
190  * @arg nlh netlink message header
191  * @arg remaining number of bytes remaining in message stream
192  *
193  * @returns the next netlink message in the message stream and
194  * decrements remaining by the size of the current message.
195  */
196 struct nlmsghdr *nlmsg_next(struct nlmsghdr *nlh, int *remaining)
197 {
198  int totlen = NLMSG_ALIGN(nlh->nlmsg_len);
199 
200  *remaining -= totlen;
201 
202  return (struct nlmsghdr *) ((unsigned char *) nlh + totlen);
203 }
204 
205 /**
206  * parse attributes of a netlink message
207  * @arg nlh netlink message header
208  * @arg hdrlen length of family specific header
209  * @arg tb destination array with maxtype+1 elements
210  * @arg maxtype maximum attribute type to be expected
211  * @arg policy validation policy
212  *
213  * See nla_parse()
214  */
215 int nlmsg_parse(struct nlmsghdr *nlh, int hdrlen, struct nlattr *tb[],
216  int maxtype, const struct nla_policy *policy)
217 {
218  if (!nlmsg_valid_hdr(nlh, hdrlen))
219  return -NLE_MSG_TOOSHORT;
220 
221  return nla_parse(tb, maxtype, nlmsg_attrdata(nlh, hdrlen),
222  nlmsg_attrlen(nlh, hdrlen), policy);
223 }
224 
225 /**
226  * nlmsg_find_attr - find a specific attribute in a netlink message
227  * @arg nlh netlink message header
228  * @arg hdrlen length of familiy specific header
229  * @arg attrtype type of attribute to look for
230  *
231  * Returns the first attribute which matches the specified type.
232  */
233 struct nlattr *nlmsg_find_attr(struct nlmsghdr *nlh, int hdrlen, int attrtype)
234 {
235  return nla_find(nlmsg_attrdata(nlh, hdrlen),
236  nlmsg_attrlen(nlh, hdrlen), attrtype);
237 }
238 
239 /**
240  * nlmsg_validate - validate a netlink message including attributes
241  * @arg nlh netlinket message header
242  * @arg hdrlen length of familiy specific header
243  * @arg maxtype maximum attribute type to be expected
244  * @arg policy validation policy
245  */
246 int nlmsg_validate(struct nlmsghdr *nlh, int hdrlen, int maxtype,
247  const struct nla_policy *policy)
248 {
249  if (!nlmsg_valid_hdr(nlh, hdrlen))
250  return -NLE_MSG_TOOSHORT;
251 
252  return nla_validate(nlmsg_attrdata(nlh, hdrlen),
253  nlmsg_attrlen(nlh, hdrlen), maxtype, policy);
254 }
255 
256 /** @} */
257 
258 /**
259  * @name Message Building/Access
260  * @{
261  */
262 
263 static struct nl_msg *__nlmsg_alloc(size_t len)
264 {
265  struct nl_msg *nm;
266 
267  if (len < sizeof(struct nlmsghdr))
268  len = sizeof(struct nlmsghdr);
269 
270  nm = calloc(1, sizeof(*nm));
271  if (!nm)
272  goto errout;
273 
274  nm->nm_refcnt = 1;
275 
276  nm->nm_nlh = calloc(1, len);
277  if (!nm->nm_nlh)
278  goto errout;
279 
280  nm->nm_protocol = -1;
281  nm->nm_size = len;
282  nm->nm_nlh->nlmsg_len = nlmsg_total_size(0);
283 
284  NL_DBG(2, "msg %p: Allocated new message, maxlen=%zu\n", nm, len);
285 
286  return nm;
287 errout:
288  free(nm);
289  return NULL;
290 }
291 
292 /**
293  * Allocate a new netlink message with the default maximum payload size.
294  *
295  * Allocates a new netlink message without any further payload. The
296  * maximum payload size defaults to PAGESIZE or as otherwise specified
297  * with nlmsg_set_default_size().
298  *
299  * @return Newly allocated netlink message or NULL.
300  */
301 struct nl_msg *nlmsg_alloc(void)
302 {
303  return __nlmsg_alloc(default_msg_size);
304 }
305 
306 /**
307  * Allocate a new netlink message with maximum payload size specified.
308  */
309 struct nl_msg *nlmsg_alloc_size(size_t max)
310 {
311  return __nlmsg_alloc(max);
312 }
313 
314 /**
315  * Allocate a new netlink message and inherit netlink message header
316  * @arg hdr Netlink message header template
317  *
318  * Allocates a new netlink message and inherits the original message
319  * header. If \a hdr is not NULL it will be used as a template for
320  * the netlink message header, otherwise the header is left blank.
321  *
322  * @return Newly allocated netlink message or NULL
323  */
324 struct nl_msg *nlmsg_inherit(struct nlmsghdr *hdr)
325 {
326  struct nl_msg *nm;
327 
328  nm = nlmsg_alloc();
329  if (nm && hdr) {
330  struct nlmsghdr *new = nm->nm_nlh;
331 
332  new->nlmsg_type = hdr->nlmsg_type;
333  new->nlmsg_flags = hdr->nlmsg_flags;
334  new->nlmsg_seq = hdr->nlmsg_seq;
335  new->nlmsg_pid = hdr->nlmsg_pid;
336  }
337 
338  return nm;
339 }
340 
341 /**
342  * Allocate a new netlink message
343  * @arg nlmsgtype Netlink message type
344  * @arg flags Message flags.
345  *
346  * @return Newly allocated netlink message or NULL.
347  */
348 struct nl_msg *nlmsg_alloc_simple(int nlmsgtype, int flags)
349 {
350  struct nl_msg *msg;
351  struct nlmsghdr nlh = {
352  .nlmsg_type = nlmsgtype,
353  .nlmsg_flags = flags,
354  .nlmsg_seq = NL_AUTO_SEQ,
355  .nlmsg_pid = NL_AUTO_PID,
356  };
357 
358  msg = nlmsg_inherit(&nlh);
359  if (msg)
360  NL_DBG(2, "msg %p: Allocated new simple message\n", msg);
361 
362  return msg;
363 }
364 
365 /**
366  * Set the default maximum message payload size for allocated messages
367  * @arg max Size of payload in bytes.
368  */
369 void nlmsg_set_default_size(size_t max)
370 {
371  if (max < nlmsg_total_size(0))
372  max = nlmsg_total_size(0);
373 
374  default_msg_size = max;
375 }
376 
377 /**
378  * Convert a netlink message received from a netlink socket to a nl_msg
379  * @arg hdr Netlink message received from netlink socket.
380  *
381  * Allocates a new netlink message and copies all of the data pointed to
382  * by \a hdr into the new message object.
383  *
384  * @return Newly allocated netlink message or NULL.
385  */
386 struct nl_msg *nlmsg_convert(struct nlmsghdr *hdr)
387 {
388  struct nl_msg *nm;
389 
390  nm = __nlmsg_alloc(NLMSG_ALIGN(hdr->nlmsg_len));
391  if (!nm)
392  return NULL;
393 
394  memcpy(nm->nm_nlh, hdr, hdr->nlmsg_len);
395 
396  return nm;
397 }
398 
399 /**
400  * Reserve room for additional data in a netlink message
401  * @arg n netlink message
402  * @arg len length of additional data to reserve room for
403  * @arg pad number of bytes to align data to
404  *
405  * Reserves room for additional data at the tail of the an
406  * existing netlink message. Eventual padding required will
407  * be zeroed out.
408  *
409  * @return Pointer to start of additional data tailroom or NULL.
410  */
411 void *nlmsg_reserve(struct nl_msg *n, size_t len, int pad)
412 {
413  char *buf = (char *) n->nm_nlh;
414  size_t nlmsg_len = n->nm_nlh->nlmsg_len;
415  size_t tlen;
416 
417  if (len > n->nm_size)
418  return NULL;
419 
420  tlen = pad ? ((len + (pad - 1)) & ~(pad - 1)) : len;
421 
422  if ((tlen + nlmsg_len) > n->nm_size)
423  return NULL;
424 
425  buf += nlmsg_len;
426  n->nm_nlh->nlmsg_len += tlen;
427 
428  if (tlen > len)
429  memset(buf + len, 0, tlen - len);
430 
431  NL_DBG(2, "msg %p: Reserved %zu (%zu) bytes, pad=%d, nlmsg_len=%d\n",
432  n, tlen, len, pad, n->nm_nlh->nlmsg_len);
433 
434  return buf;
435 }
436 
437 /**
438  * Append data to tail of a netlink message
439  * @arg n netlink message
440  * @arg data data to add
441  * @arg len length of data
442  * @arg pad Number of bytes to align data to.
443  *
444  * Extends the netlink message as needed and appends the data of given
445  * length to the message.
446  *
447  * @return 0 on success or a negative error code
448  */
449 int nlmsg_append(struct nl_msg *n, void *data, size_t len, int pad)
450 {
451  void *tmp;
452 
453  tmp = nlmsg_reserve(n, len, pad);
454  if (tmp == NULL)
455  return -NLE_NOMEM;
456 
457  memcpy(tmp, data, len);
458  NL_DBG(2, "msg %p: Appended %zu bytes with padding %d\n", n, len, pad);
459 
460  return 0;
461 }
462 
463 /**
464  * Expand maximum payload size of a netlink message
465  * @arg n Netlink message.
466  * @arg newlen New maximum payload size.
467  *
468  * Reallocates the payload section of a netlink message and increases
469  * the maximum payload size of the message.
470  *
471  * @note Any pointers pointing to old payload block will be stale and
472  * need to be refetched. Therfore, do not expand while constructing
473  * nested attributes or while reserved data blocks are held.
474  *
475  * @return 0 on success or a negative error code.
476  */
477 int nlmsg_expand(struct nl_msg *n, size_t newlen)
478 {
479  void *tmp;
480 
481  if (newlen <= n->nm_size)
482  return -NLE_INVAL;
483 
484  tmp = realloc(n->nm_nlh, newlen);
485  if (tmp == NULL)
486  return -NLE_NOMEM;
487 
488  n->nm_nlh = tmp;
489  n->nm_size = newlen;
490 
491  return 0;
492 }
493 
494 /**
495  * Add a netlink message header to a netlink message
496  * @arg n netlink message
497  * @arg pid netlink process id or NL_AUTO_PID
498  * @arg seq sequence number of message or NL_AUTO_SEQ
499  * @arg type message type
500  * @arg payload length of message payload
501  * @arg flags message flags
502  *
503  * Adds or overwrites the netlink message header in an existing message
504  * object. If \a payload is greater-than zero additional room will be
505  * reserved, f.e. for family specific headers. It can be accesed via
506  * nlmsg_data().
507  *
508  * @return A pointer to the netlink message header or NULL.
509  */
510 struct nlmsghdr *nlmsg_put(struct nl_msg *n, uint32_t pid, uint32_t seq,
511  int type, int payload, int flags)
512 {
513  struct nlmsghdr *nlh;
514 
515  if (n->nm_nlh->nlmsg_len < NLMSG_HDRLEN)
516  BUG();
517 
518  nlh = (struct nlmsghdr *) n->nm_nlh;
519  nlh->nlmsg_type = type;
520  nlh->nlmsg_flags = flags;
521  nlh->nlmsg_pid = pid;
522  nlh->nlmsg_seq = seq;
523 
524  NL_DBG(2, "msg %p: Added netlink header type=%d, flags=%d, pid=%d, "
525  "seq=%d\n", n, type, flags, pid, seq);
526 
527  if (payload > 0 &&
528  nlmsg_reserve(n, payload, NLMSG_ALIGNTO) == NULL)
529  return NULL;
530 
531  return nlh;
532 }
533 
534 /**
535  * Return actual netlink message
536  * @arg n netlink message
537  *
538  * Returns the actual netlink message casted to the type of the netlink
539  * message header.
540  *
541  * @return A pointer to the netlink message.
542  */
543 struct nlmsghdr *nlmsg_hdr(struct nl_msg *n)
544 {
545  return n->nm_nlh;
546 }
547 
548 /**
549  * Acquire a reference on a netlink message
550  * @arg msg message to acquire reference from
551  */
552 void nlmsg_get(struct nl_msg *msg)
553 {
554  msg->nm_refcnt++;
555  NL_DBG(4, "New reference to message %p, total %d\n",
556  msg, msg->nm_refcnt);
557 }
558 
559 /**
560  * Release a reference from an netlink message
561  * @arg msg message to release reference from
562  *
563  * Frees memory after the last reference has been released.
564  */
565 void nlmsg_free(struct nl_msg *msg)
566 {
567  if (!msg)
568  return;
569 
570  msg->nm_refcnt--;
571  NL_DBG(4, "Returned message reference %p, %d remaining\n",
572  msg, msg->nm_refcnt);
573 
574  if (msg->nm_refcnt < 0)
575  BUG();
576 
577  if (msg->nm_refcnt <= 0) {
578  free(msg->nm_nlh);
579  NL_DBG(2, "msg %p: Freed\n", msg);
580  free(msg);
581  }
582 }
583 
584 /** @} */
585 
586 /**
587  * @name Attributes
588  * @{
589  */
590 
591 void nlmsg_set_proto(struct nl_msg *msg, int protocol)
592 {
593  msg->nm_protocol = protocol;
594 }
595 
596 int nlmsg_get_proto(struct nl_msg *msg)
597 {
598  return msg->nm_protocol;
599 }
600 
601 size_t nlmsg_get_max_size(struct nl_msg *msg)
602 {
603  return msg->nm_size;
604 }
605 
606 void nlmsg_set_src(struct nl_msg *msg, struct sockaddr_nl *addr)
607 {
608  memcpy(&msg->nm_src, addr, sizeof(*addr));
609 }
610 
611 struct sockaddr_nl *nlmsg_get_src(struct nl_msg *msg)
612 {
613  return &msg->nm_src;
614 }
615 
616 void nlmsg_set_dst(struct nl_msg *msg, struct sockaddr_nl *addr)
617 {
618  memcpy(&msg->nm_dst, addr, sizeof(*addr));
619 }
620 
621 struct sockaddr_nl *nlmsg_get_dst(struct nl_msg *msg)
622 {
623  return &msg->nm_dst;
624 }
625 
626 void nlmsg_set_creds(struct nl_msg *msg, struct ucred *creds)
627 {
628  memcpy(&msg->nm_creds, creds, sizeof(*creds));
629  msg->nm_flags |= NL_MSG_CRED_PRESENT;
630 }
631 
632 struct ucred *nlmsg_get_creds(struct nl_msg *msg)
633 {
634  if (msg->nm_flags & NL_MSG_CRED_PRESENT)
635  return &msg->nm_creds;
636  return NULL;
637 }
638 
639 /** @} */
640 
641 /**
642  * @name Netlink Message Type Translations
643  * @{
644  */
645 
646 static const struct trans_tbl nl_msgtypes[] = {
647  __ADD(NLMSG_NOOP,NOOP),
648  __ADD(NLMSG_ERROR,ERROR),
649  __ADD(NLMSG_DONE,DONE),
650  __ADD(NLMSG_OVERRUN,OVERRUN),
651 };
652 
653 char *nl_nlmsgtype2str(int type, char *buf, size_t size)
654 {
655  return __type2str(type, buf, size, nl_msgtypes,
656  ARRAY_SIZE(nl_msgtypes));
657 }
658 
659 int nl_str2nlmsgtype(const char *name)
660 {
661  return __str2type(name, nl_msgtypes, ARRAY_SIZE(nl_msgtypes));
662 }
663 
664 /** @} */
665 
666 /**
667  * @name Netlink Message Flags Translations
668  * @{
669  */
670 
671 char *nl_nlmsg_flags2str(int flags, char *buf, size_t len)
672 {
673  memset(buf, 0, len);
674 
675 #define PRINT_FLAG(f) \
676  if (flags & NLM_F_##f) { \
677  flags &= ~NLM_F_##f; \
678  strncat(buf, #f, len - strlen(buf) - 1); \
679  if (flags) \
680  strncat(buf, ",", len - strlen(buf) - 1); \
681  }
682 
683  PRINT_FLAG(REQUEST);
684  PRINT_FLAG(MULTI);
685  PRINT_FLAG(ACK);
686  PRINT_FLAG(ECHO);
687  PRINT_FLAG(ROOT);
688  PRINT_FLAG(MATCH);
689  PRINT_FLAG(ATOMIC);
690  PRINT_FLAG(REPLACE);
691  PRINT_FLAG(EXCL);
692  PRINT_FLAG(CREATE);
693  PRINT_FLAG(APPEND);
694 
695  if (flags) {
696  char s[32];
697  snprintf(s, sizeof(s), "0x%x", flags);
698  strncat(buf, s, len - strlen(buf) - 1);
699  }
700 #undef PRINT_FLAG
701 
702  return buf;
703 }
704 
705 /** @} */
706 
707 /**
708  * @name Direct Parsing
709  * @{
710  */
711 
712 /** @cond SKIP */
713 struct dp_xdata {
714  void (*cb)(struct nl_object *, void *);
715  void *arg;
716 };
717 /** @endcond */
718 
719 static int parse_cb(struct nl_object *obj, struct nl_parser_param *p)
720 {
721  struct dp_xdata *x = p->pp_arg;
722 
723  x->cb(obj, x->arg);
724  return 0;
725 }
726 
727 int nl_msg_parse(struct nl_msg *msg, void (*cb)(struct nl_object *, void *),
728  void *arg)
729 {
730  struct nl_cache_ops *ops;
731  struct nl_parser_param p = {
732  .pp_cb = parse_cb
733  };
734  struct dp_xdata x = {
735  .cb = cb,
736  .arg = arg,
737  };
738  int err;
739 
740  ops = nl_cache_ops_associate_safe(nlmsg_get_proto(msg),
741  nlmsg_hdr(msg)->nlmsg_type);
742  if (ops == NULL)
743  return -NLE_MSGTYPE_NOSUPPORT;
744  p.pp_arg = &x;
745 
746  err = nl_cache_parse(ops, NULL, nlmsg_hdr(msg), &p);
747  nl_cache_ops_put(ops);
748 
749  return err;
750 }
751 
752 /** @} */
753 
754 /**
755  * @name Dumping
756  * @{
757  */
758 
759 static void prefix_line(FILE *ofd, int prefix)
760 {
761  int i;
762 
763  for (i = 0; i < prefix; i++)
764  fprintf(ofd, " ");
765 }
766 
767 static inline void dump_hex(FILE *ofd, char *start, int len, int prefix)
768 {
769  int i, a, c, limit;
770  char ascii[21] = {0};
771 
772  limit = 16 - (prefix * 2);
773  prefix_line(ofd, prefix);
774  fprintf(ofd, " ");
775 
776  for (i = 0, a = 0, c = 0; i < len; i++) {
777  int v = *(uint8_t *) (start + i);
778 
779  fprintf(ofd, "%02x ", v);
780  ascii[a++] = isprint(v) ? v : '.';
781 
782  if (++c >= limit) {
783  fprintf(ofd, "%s\n", ascii);
784  if (i < (len - 1)) {
785  prefix_line(ofd, prefix);
786  fprintf(ofd, " ");
787  }
788  a = c = 0;
789  memset(ascii, 0, sizeof(ascii));
790  }
791  }
792 
793  if (c != 0) {
794  for (i = 0; i < (limit - c); i++)
795  fprintf(ofd, " ");
796  fprintf(ofd, "%s\n", ascii);
797  }
798 }
799 
800 static void print_hdr(FILE *ofd, struct nl_msg *msg)
801 {
802  struct nlmsghdr *nlh = nlmsg_hdr(msg);
803  struct nl_cache_ops *ops;
804  struct nl_msgtype *mt;
805  char buf[128];
806 
807  fprintf(ofd, " .nlmsg_len = %d\n", nlh->nlmsg_len);
808 
809  ops = nl_cache_ops_associate_safe(nlmsg_get_proto(msg), nlh->nlmsg_type);
810  if (ops) {
811  mt = nl_msgtype_lookup(ops, nlh->nlmsg_type);
812  if (!mt)
813  BUG();
814 
815  snprintf(buf, sizeof(buf), "%s::%s", ops->co_name, mt->mt_name);
816  nl_cache_ops_put(ops);
817  } else
818  nl_nlmsgtype2str(nlh->nlmsg_type, buf, sizeof(buf));
819 
820  fprintf(ofd, " .type = %d <%s>\n", nlh->nlmsg_type, buf);
821  fprintf(ofd, " .flags = %d <%s>\n", nlh->nlmsg_flags,
822  nl_nlmsg_flags2str(nlh->nlmsg_flags, buf, sizeof(buf)));
823  fprintf(ofd, " .seq = %d\n", nlh->nlmsg_seq);
824  fprintf(ofd, " .port = %d\n", nlh->nlmsg_pid);
825 
826 }
827 
828 static void print_genl_hdr(FILE *ofd, void *start)
829 {
830  struct genlmsghdr *ghdr = start;
831 
832  fprintf(ofd, " [GENERIC NETLINK HEADER] %zu octets\n", GENL_HDRLEN);
833  fprintf(ofd, " .cmd = %u\n", ghdr->cmd);
834  fprintf(ofd, " .version = %u\n", ghdr->version);
835  fprintf(ofd, " .unused = %#x\n", ghdr->reserved);
836 }
837 
838 static void *print_genl_msg(struct nl_msg *msg, FILE *ofd, struct nlmsghdr *hdr,
839  struct nl_cache_ops *ops, int *payloadlen)
840 {
841  char *data = nlmsg_data(hdr);
842 
843  if (*payloadlen < GENL_HDRLEN)
844  return data;
845 
846  print_genl_hdr(ofd, data);
847 
848  *payloadlen -= GENL_HDRLEN;
849  data += GENL_HDRLEN;
850 
851  if (ops) {
852  int hdrsize = ops->co_hdrsize - GENL_HDRLEN;
853 
854  if (hdrsize > 0) {
855  if (*payloadlen < hdrsize)
856  return data;
857 
858  fprintf(ofd, " [HEADER] %d octets\n", hdrsize);
859  dump_hex(ofd, data, hdrsize, 0);
860 
861  *payloadlen -= hdrsize;
862  data += hdrsize;
863  }
864  }
865 
866  return data;
867 }
868 
869 static void dump_attr(FILE *ofd, struct nlattr *attr, int prefix)
870 {
871  int len = nla_len(attr);
872 
873  dump_hex(ofd, nla_data(attr), len, prefix);
874 }
875 
876 static void dump_attrs(FILE *ofd, struct nlattr *attrs, int attrlen,
877  int prefix)
878 {
879  int rem;
880  struct nlattr *nla;
881 
882  nla_for_each_attr(nla, attrs, attrlen, rem) {
883  int padlen, alen = nla_len(nla);
884 
885  prefix_line(ofd, prefix);
886 
887  if (nla->nla_type == 0)
888  fprintf(ofd, " [ATTR PADDING] %d octets\n", alen);
889  else
890  fprintf(ofd, " [ATTR %02d%s] %d octets\n", nla_type(nla),
891  nla_is_nested(nla) ? " NESTED" : "",
892  alen);
893 
894  if (nla_is_nested(nla))
895  dump_attrs(ofd, nla_data(nla), alen, prefix+1);
896  else
897  dump_attr(ofd, nla, prefix);
898 
899  padlen = nla_padlen(alen);
900  if (padlen > 0) {
901  prefix_line(ofd, prefix);
902  fprintf(ofd, " [PADDING] %d octets\n",
903  padlen);
904  dump_hex(ofd, (char *) nla_data(nla) + alen,
905  padlen, prefix);
906  }
907  }
908 
909  if (rem) {
910  prefix_line(ofd, prefix);
911  fprintf(ofd, " [LEFTOVER] %d octets\n", rem);
912  }
913 }
914 
915 static void dump_error_msg(struct nl_msg *msg, FILE *ofd)
916 {
917  struct nlmsghdr *hdr = nlmsg_hdr(msg);
918  struct nlmsgerr *err = nlmsg_data(hdr);
919 
920  fprintf(ofd, " [ERRORMSG] %zu octets\n", sizeof(*err));
921 
922  if (nlmsg_len(hdr) >= sizeof(*err)) {
923  struct nl_msg *errmsg;
924 
925  fprintf(ofd, " .error = %d \"%s\"\n", err->error,
926  nl_strerror_l(-err->error));
927  fprintf(ofd, " [ORIGINAL MESSAGE] %zu octets\n", sizeof(*hdr));
928 
929  errmsg = nlmsg_inherit(&err->msg);
930  print_hdr(ofd, errmsg);
931  nlmsg_free(errmsg);
932  }
933 }
934 
935 static void print_msg(struct nl_msg *msg, FILE *ofd, struct nlmsghdr *hdr)
936 {
937  struct nl_cache_ops *ops;
938  int payloadlen = nlmsg_len(hdr);
939  int attrlen = 0;
940  void *data;
941 
942  data = nlmsg_data(hdr);
943  ops = nl_cache_ops_associate_safe(nlmsg_get_proto(msg),
944  hdr->nlmsg_type);
945  if (ops) {
946  attrlen = nlmsg_attrlen(hdr, ops->co_hdrsize);
947  payloadlen -= attrlen;
948  }
949 
950  if (msg->nm_protocol == NETLINK_GENERIC)
951  data = print_genl_msg(msg, ofd, hdr, ops, &payloadlen);
952 
953  if (payloadlen) {
954  fprintf(ofd, " [PAYLOAD] %d octets\n", payloadlen);
955  dump_hex(ofd, data, payloadlen, 0);
956  }
957 
958  if (attrlen) {
959  struct nlattr *attrs;
960  int attrlen;
961 
962  attrs = nlmsg_attrdata(hdr, ops->co_hdrsize);
963  attrlen = nlmsg_attrlen(hdr, ops->co_hdrsize);
964  dump_attrs(ofd, attrs, attrlen, 0);
965  }
966 
967  if (ops)
968  nl_cache_ops_put(ops);
969 }
970 
971 /**
972  * Dump message in human readable format to file descriptor
973  * @arg msg Message to print
974  * @arg ofd File descriptor.
975  */
976 void nl_msg_dump(struct nl_msg *msg, FILE *ofd)
977 {
978  struct nlmsghdr *hdr = nlmsg_hdr(msg);
979 
980  fprintf(ofd,
981  "-------------------------- BEGIN NETLINK MESSAGE ---------------------------\n");
982 
983  fprintf(ofd, " [NETLINK HEADER] %zu octets\n", sizeof(struct nlmsghdr));
984  print_hdr(ofd, msg);
985 
986  if (hdr->nlmsg_type == NLMSG_ERROR)
987  dump_error_msg(msg, ofd);
988  else if (nlmsg_len(hdr) > 0)
989  print_msg(msg, ofd, hdr);
990 
991  fprintf(ofd,
992  "--------------------------- END NETLINK MESSAGE ---------------------------\n");
993 }
994 
995 /** @} */
996 
997 /** @} */
struct nl_msg * nlmsg_alloc_size(size_t max)
Allocate a new netlink message with maximum payload size specified.
Definition: msg.c:309
int nla_parse(struct nlattr *tb[], int maxtype, struct nlattr *head, int len, const struct nla_policy *policy)
Create attribute index based on a stream of attributes.
Definition: attr.c:243
int nla_padlen(int payload)
Return length of padding at the tail of the attribute.
Definition: attr.c:92
void nl_cache_ops_put(struct nl_cache_ops *ops)
Decrement reference counter.
Definition: cache_mngt.c:66
void nlmsg_free(struct nl_msg *msg)
Release a reference from an netlink message.
Definition: msg.c:565
int nlmsg_parse(struct nlmsghdr *nlh, int hdrlen, struct nlattr *tb[], int maxtype, const struct nla_policy *policy)
parse attributes of a netlink message
Definition: msg.c:215
int nlmsg_attrlen(const struct nlmsghdr *nlh, int hdrlen)
length of attributes data
Definition: msg.c:156
struct nlattr * nla_find(const struct nlattr *head, int len, int attrtype)
Find a single attribute in a stream of attributes.
Definition: attr.c:324
void * nlmsg_data(const struct nlmsghdr *nlh)
Return pointer to message payload.
Definition: msg.c:107
int nlmsg_size(int payload)
Calculates size of netlink message based on payload length.
Definition: msg.c:56
struct nl_msg * nlmsg_inherit(struct nlmsghdr *hdr)
Allocate a new netlink message and inherit netlink message header.
Definition: msg.c:324
void * nlmsg_reserve(struct nl_msg *n, size_t len, int pad)
Reserve room for additional data in a netlink message.
Definition: msg.c:411
Attribute validation policy.
Definition: attr.h:69
#define NL_AUTO_SEQ
May be used to refer to a sequence number which should be automatically set just before sending the m...
Definition: msg.h:46
struct nl_msg * nlmsg_alloc(void)
Allocate a new netlink message with the default maximum payload size.
Definition: msg.c:301
void nlmsg_set_default_size(size_t max)
Set the default maximum message payload size for allocated messages.
Definition: msg.c:369
int nlmsg_ok(const struct nlmsghdr *nlh, int remaining)
check if the netlink message fits into the remaining bytes
Definition: msg.c:181
struct nlattr * nlmsg_find_attr(struct nlmsghdr *nlh, int hdrlen, int attrtype)
nlmsg_find_attr - find a specific attribute in a netlink message
Definition: msg.c:233
int nla_is_nested(const struct nlattr *attr)
Return true if attribute has NLA_F_NESTED flag set.
Definition: attr.c:1033
int nlmsg_total_size(int payload)
Calculates size of netlink message including padding based on payload length.
Definition: msg.c:74
struct nlattr * nlmsg_attrdata(const struct nlmsghdr *nlh, int hdrlen)
head of attributes data
Definition: msg.c:145
struct nlmsghdr * nlmsg_next(struct nlmsghdr *nlh, int *remaining)
next netlink message in message stream
Definition: msg.c:196
struct nlmsghdr * nlmsg_put(struct nl_msg *n, uint32_t pid, uint32_t seq, int type, int payload, int flags)
Add a netlink message header to a netlink message.
Definition: msg.c:510
int nlmsg_datalen(const struct nlmsghdr *nlh)
Return length of message payload.
Definition: msg.c:123
void nl_msg_dump(struct nl_msg *msg, FILE *ofd)
Dump message in human readable format to file descriptor.
Definition: msg.c:976
int nla_type(const struct nlattr *nla)
Return type of the attribute.
Definition: attr.c:110
struct nlmsghdr * nlmsg_hdr(struct nl_msg *n)
Return actual netlink message.
Definition: msg.c:543
void * nla_data(const struct nlattr *nla)
Return pointer to the payload section.
Definition: attr.c:121
int nlmsg_expand(struct nl_msg *n, size_t newlen)
Expand maximum payload size of a netlink message.
Definition: msg.c:477
int nla_len(const struct nlattr *nla)
Return length of the payload .
Definition: attr.c:132
int nlmsg_validate(struct nlmsghdr *nlh, int hdrlen, int maxtype, const struct nla_policy *policy)
nlmsg_validate - validate a netlink message including attributes
Definition: msg.c:246
int nlmsg_padlen(int payload)
Size of padding that needs to be added at end of message.
Definition: msg.c:89
void nlmsg_get(struct nl_msg *msg)
Acquire a reference on a netlink message.
Definition: msg.c:552
int nlmsg_append(struct nl_msg *n, void *data, size_t len, int pad)
Append data to tail of a netlink message.
Definition: msg.c:449
struct nl_msg * nlmsg_alloc_simple(int nlmsgtype, int flags)
Allocate a new netlink message.
Definition: msg.c:348
struct nl_msg * nlmsg_convert(struct nlmsghdr *hdr)
Convert a netlink message received from a netlink socket to a nl_msg.
Definition: msg.c:386
struct nl_msgtype * nl_msgtype_lookup(struct nl_cache_ops *ops, int msgtype)
Lookup message type cache association.
Definition: cache_mngt.c:190
struct nl_cache_ops * nl_cache_ops_associate_safe(int protocol, int msgtype)
Associate protocol and message type to cache operations.
Definition: cache_mngt.c:165
#define nla_for_each_attr(pos, head, len, rem)
Iterate over a stream of attributes.
Definition: attr.h:318
int nla_validate(const struct nlattr *head, int len, int maxtype, const struct nla_policy *policy)
Validate a stream of attributes.
Definition: attr.c:295