libnl  3.2.24-rc1
msg.c
1 /*
2  * lib/msg.c Netlink Messages Interface
3  *
4  * This library is free software; you can redistribute it and/or
5  * modify it under the terms of the GNU Lesser General Public
6  * License as published by the Free Software Foundation version 2.1
7  * of the License.
8  *
9  * Copyright (c) 2003-2012 Thomas Graf <tgraf@suug.ch>
10  */
11 
12 /**
13  * @ingroup core
14  * @defgroup msg Message Construction & Parsing
15  * Netlink Message Construction/Parsing Interface
16  *
17  * Related sections in the development guide:
18  * - @core_doc{_message_parsing_amp_construction,Message Parsing & Construction}
19  *
20  * @{
21  *
22  * Header
23  * ------
24  * ~~~~{.c}
25  * #include <netlink/msg.h>
26  * ~~~~
27  */
28 
29 #include <netlink-private/netlink.h>
30 #include <netlink/netlink.h>
31 #include <netlink/utils.h>
32 #include <netlink/cache.h>
33 #include <netlink/attr.h>
34 #include <linux/socket.h>
35 
36 static size_t default_msg_size;
37 
38 static void __init init_msg_size(void)
39 {
40  default_msg_size = getpagesize();
41 }
42 
43 /**
44  * @name Size Calculations
45  * @{
46  */
47 
48 /**
49  * Calculates size of netlink message based on payload length.
50  * @arg payload Length of payload
51  *
52  * @return size of netlink message without padding.
53  */
54 int nlmsg_size(int payload)
55 {
56  return NLMSG_HDRLEN + payload;
57 }
58 
59 static int nlmsg_msg_size(int payload)
60 {
61  return nlmsg_size(payload);
62 }
63 
64 /**
65  * Calculates size of netlink message including padding based on payload length
66  * @arg payload Length of payload
67  *
68  * This function is idential to nlmsg_size() + nlmsg_padlen().
69  *
70  * @return Size of netlink message including padding.
71  */
72 int nlmsg_total_size(int payload)
73 {
74  return NLMSG_ALIGN(nlmsg_msg_size(payload));
75 }
76 
77 /**
78  * Size of padding that needs to be added at end of message
79  * @arg payload Length of payload
80  *
81  * Calculates the number of bytes of padding which is required to be added to
82  * the end of the message to ensure that the next netlink message header begins
83  * properly aligned to NLMSG_ALIGNTO.
84  *
85  * @return Number of bytes of padding needed.
86  */
87 int nlmsg_padlen(int payload)
88 {
89  return nlmsg_total_size(payload) - nlmsg_msg_size(payload);
90 }
91 
92 /** @} */
93 
94 /**
95  * @name Access to Message Payload
96  * @{
97  */
98 
99 /**
100  * Return pointer to message payload
101  * @arg nlh Netlink message header
102  *
103  * @return Pointer to start of message payload.
104  */
105 void *nlmsg_data(const struct nlmsghdr *nlh)
106 {
107  return (unsigned char *) nlh + NLMSG_HDRLEN;
108 }
109 
110 void *nlmsg_tail(const struct nlmsghdr *nlh)
111 {
112  return (unsigned char *) nlh + NLMSG_ALIGN(nlh->nlmsg_len);
113 }
114 
115 /**
116  * Return length of message payload
117  * @arg nlh Netlink message header
118  *
119  * @return Length of message payload in bytes.
120  */
121 int nlmsg_datalen(const struct nlmsghdr *nlh)
122 {
123  return nlh->nlmsg_len - NLMSG_HDRLEN;
124 }
125 
126 static int nlmsg_len(const struct nlmsghdr *nlh)
127 {
128  return nlmsg_datalen(nlh);
129 }
130 
131 /** @} */
132 
133 /**
134  * @name Attribute Access
135  * @{
136  */
137 
138 /**
139  * head of attributes data
140  * @arg nlh netlink message header
141  * @arg hdrlen length of family specific header
142  */
143 struct nlattr *nlmsg_attrdata(const struct nlmsghdr *nlh, int hdrlen)
144 {
145  unsigned char *data = nlmsg_data(nlh);
146  return (struct nlattr *) (data + NLMSG_ALIGN(hdrlen));
147 }
148 
149 /**
150  * length of attributes data
151  * @arg nlh netlink message header
152  * @arg hdrlen length of family specific header
153  */
154 int nlmsg_attrlen(const struct nlmsghdr *nlh, int hdrlen)
155 {
156  return max_t(int, nlmsg_len(nlh) - NLMSG_ALIGN(hdrlen), 0);
157 }
158 
159 /** @} */
160 
161 /**
162  * @name Message Parsing
163  * @{
164  */
165 
166 int nlmsg_valid_hdr(const struct nlmsghdr *nlh, int hdrlen)
167 {
168  if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
169  return 0;
170 
171  return 1;
172 }
173 
174 /**
175  * check if the netlink message fits into the remaining bytes
176  * @arg nlh netlink message header
177  * @arg remaining number of bytes remaining in message stream
178  */
179 int nlmsg_ok(const struct nlmsghdr *nlh, int remaining)
180 {
181  return (remaining >= (int)sizeof(struct nlmsghdr) &&
182  nlh->nlmsg_len >= sizeof(struct nlmsghdr) &&
183  nlh->nlmsg_len <= remaining);
184 }
185 
186 /**
187  * next netlink message in message stream
188  * @arg nlh netlink message header
189  * @arg remaining number of bytes remaining in message stream
190  *
191  * @returns the next netlink message in the message stream and
192  * decrements remaining by the size of the current message.
193  */
194 struct nlmsghdr *nlmsg_next(struct nlmsghdr *nlh, int *remaining)
195 {
196  int totlen = NLMSG_ALIGN(nlh->nlmsg_len);
197 
198  *remaining -= totlen;
199 
200  return (struct nlmsghdr *) ((unsigned char *) nlh + totlen);
201 }
202 
203 /**
204  * parse attributes of a netlink message
205  * @arg nlh netlink message header
206  * @arg hdrlen length of family specific header
207  * @arg tb destination array with maxtype+1 elements
208  * @arg maxtype maximum attribute type to be expected
209  * @arg policy validation policy
210  *
211  * See nla_parse()
212  */
213 int nlmsg_parse(struct nlmsghdr *nlh, int hdrlen, struct nlattr *tb[],
214  int maxtype, struct nla_policy *policy)
215 {
216  if (!nlmsg_valid_hdr(nlh, hdrlen))
217  return -NLE_MSG_TOOSHORT;
218 
219  return nla_parse(tb, maxtype, nlmsg_attrdata(nlh, hdrlen),
220  nlmsg_attrlen(nlh, hdrlen), policy);
221 }
222 
223 /**
224  * nlmsg_find_attr - find a specific attribute in a netlink message
225  * @arg nlh netlink message header
226  * @arg hdrlen length of familiy specific header
227  * @arg attrtype type of attribute to look for
228  *
229  * Returns the first attribute which matches the specified type.
230  */
231 struct nlattr *nlmsg_find_attr(struct nlmsghdr *nlh, int hdrlen, int attrtype)
232 {
233  return nla_find(nlmsg_attrdata(nlh, hdrlen),
234  nlmsg_attrlen(nlh, hdrlen), attrtype);
235 }
236 
237 /**
238  * nlmsg_validate - validate a netlink message including attributes
239  * @arg nlh netlinket message header
240  * @arg hdrlen length of familiy specific header
241  * @arg maxtype maximum attribute type to be expected
242  * @arg policy validation policy
243  */
244 int nlmsg_validate(struct nlmsghdr *nlh, int hdrlen, int maxtype,
245  struct nla_policy *policy)
246 {
247  if (!nlmsg_valid_hdr(nlh, hdrlen))
248  return -NLE_MSG_TOOSHORT;
249 
250  return nla_validate(nlmsg_attrdata(nlh, hdrlen),
251  nlmsg_attrlen(nlh, hdrlen), maxtype, policy);
252 }
253 
254 /** @} */
255 
256 /**
257  * @name Message Building/Access
258  * @{
259  */
260 
261 static struct nl_msg *__nlmsg_alloc(size_t len)
262 {
263  struct nl_msg *nm;
264 
265  if (len < sizeof(struct nlmsghdr))
266  len = sizeof(struct nlmsghdr);
267 
268  nm = calloc(1, sizeof(*nm));
269  if (!nm)
270  goto errout;
271 
272  nm->nm_refcnt = 1;
273 
274  nm->nm_nlh = calloc(1, len);
275  if (!nm->nm_nlh)
276  goto errout;
277 
278  nm->nm_protocol = -1;
279  nm->nm_size = len;
280  nm->nm_nlh->nlmsg_len = nlmsg_total_size(0);
281 
282  NL_DBG(2, "msg %p: Allocated new message, maxlen=%zu\n", nm, len);
283 
284  return nm;
285 errout:
286  free(nm);
287  return NULL;
288 }
289 
290 /**
291  * Allocate a new netlink message with the default maximum payload size.
292  *
293  * Allocates a new netlink message without any further payload. The
294  * maximum payload size defaults to PAGESIZE or as otherwise specified
295  * with nlmsg_set_default_size().
296  *
297  * @return Newly allocated netlink message or NULL.
298  */
299 struct nl_msg *nlmsg_alloc(void)
300 {
301  return __nlmsg_alloc(default_msg_size);
302 }
303 
304 /**
305  * Allocate a new netlink message with maximum payload size specified.
306  */
307 struct nl_msg *nlmsg_alloc_size(size_t max)
308 {
309  return __nlmsg_alloc(max);
310 }
311 
312 /**
313  * Allocate a new netlink message and inherit netlink message header
314  * @arg hdr Netlink message header template
315  *
316  * Allocates a new netlink message and inherits the original message
317  * header. If \a hdr is not NULL it will be used as a template for
318  * the netlink message header, otherwise the header is left blank.
319  *
320  * @return Newly allocated netlink message or NULL
321  */
322 struct nl_msg *nlmsg_inherit(struct nlmsghdr *hdr)
323 {
324  struct nl_msg *nm;
325 
326  nm = nlmsg_alloc();
327  if (nm && hdr) {
328  struct nlmsghdr *new = nm->nm_nlh;
329 
330  new->nlmsg_type = hdr->nlmsg_type;
331  new->nlmsg_flags = hdr->nlmsg_flags;
332  new->nlmsg_seq = hdr->nlmsg_seq;
333  new->nlmsg_pid = hdr->nlmsg_pid;
334  }
335 
336  return nm;
337 }
338 
339 /**
340  * Allocate a new netlink message
341  * @arg nlmsgtype Netlink message type
342  * @arg flags Message flags.
343  *
344  * @return Newly allocated netlink message or NULL.
345  */
346 struct nl_msg *nlmsg_alloc_simple(int nlmsgtype, int flags)
347 {
348  struct nl_msg *msg;
349  struct nlmsghdr nlh = {
350  .nlmsg_type = nlmsgtype,
351  .nlmsg_flags = flags,
352  };
353 
354  msg = nlmsg_inherit(&nlh);
355  if (msg)
356  NL_DBG(2, "msg %p: Allocated new simple message\n", msg);
357 
358  return msg;
359 }
360 
361 /**
362  * Set the default maximum message payload size for allocated messages
363  * @arg max Size of payload in bytes.
364  */
365 void nlmsg_set_default_size(size_t max)
366 {
367  if (max < nlmsg_total_size(0))
368  max = nlmsg_total_size(0);
369 
370  default_msg_size = max;
371 }
372 
373 /**
374  * Convert a netlink message received from a netlink socket to a nl_msg
375  * @arg hdr Netlink message received from netlink socket.
376  *
377  * Allocates a new netlink message and copies all of the data pointed to
378  * by \a hdr into the new message object.
379  *
380  * @return Newly allocated netlink message or NULL.
381  */
382 struct nl_msg *nlmsg_convert(struct nlmsghdr *hdr)
383 {
384  struct nl_msg *nm;
385 
386  nm = __nlmsg_alloc(NLMSG_ALIGN(hdr->nlmsg_len));
387  if (!nm)
388  goto errout;
389 
390  memcpy(nm->nm_nlh, hdr, hdr->nlmsg_len);
391 
392  return nm;
393 errout:
394  nlmsg_free(nm);
395  return NULL;
396 }
397 
398 /**
399  * Reserve room for additional data in a netlink message
400  * @arg n netlink message
401  * @arg len length of additional data to reserve room for
402  * @arg pad number of bytes to align data to
403  *
404  * Reserves room for additional data at the tail of the an
405  * existing netlink message. Eventual padding required will
406  * be zeroed out.
407  *
408  * @return Pointer to start of additional data tailroom or NULL.
409  */
410 void *nlmsg_reserve(struct nl_msg *n, size_t len, int pad)
411 {
412  void *buf = n->nm_nlh;
413  size_t nlmsg_len = n->nm_nlh->nlmsg_len;
414  size_t tlen;
415 
416  tlen = pad ? ((len + (pad - 1)) & ~(pad - 1)) : len;
417 
418  if ((tlen + nlmsg_len) > n->nm_size)
419  return NULL;
420 
421  buf += nlmsg_len;
422  n->nm_nlh->nlmsg_len += tlen;
423 
424  if (tlen > len)
425  memset(buf + len, 0, tlen - len);
426 
427  NL_DBG(2, "msg %p: Reserved %zu (%zu) bytes, pad=%d, nlmsg_len=%d\n",
428  n, tlen, len, pad, n->nm_nlh->nlmsg_len);
429 
430  return buf;
431 }
432 
433 /**
434  * Append data to tail of a netlink message
435  * @arg n netlink message
436  * @arg data data to add
437  * @arg len length of data
438  * @arg pad Number of bytes to align data to.
439  *
440  * Extends the netlink message as needed and appends the data of given
441  * length to the message.
442  *
443  * @return 0 on success or a negative error code
444  */
445 int nlmsg_append(struct nl_msg *n, void *data, size_t len, int pad)
446 {
447  void *tmp;
448 
449  tmp = nlmsg_reserve(n, len, pad);
450  if (tmp == NULL)
451  return -NLE_NOMEM;
452 
453  memcpy(tmp, data, len);
454  NL_DBG(2, "msg %p: Appended %zu bytes with padding %d\n", n, len, pad);
455 
456  return 0;
457 }
458 
459 /**
460  * Expand maximum payload size of a netlink message
461  * @arg n Netlink message.
462  * @arg newlen New maximum payload size.
463  *
464  * Reallocates the payload section of a netlink message and increases
465  * the maximum payload size of the message.
466  *
467  * @note Any pointers pointing to old payload block will be stale and
468  * need to be refetched. Therfore, do not expand while constructing
469  * nested attributes or while reserved data blocks are held.
470  *
471  * @return 0 on success or a negative error code.
472  */
473 int nlmsg_expand(struct nl_msg *n, size_t newlen)
474 {
475  void *tmp;
476 
477  if (newlen <= n->nm_size)
478  return -NLE_INVAL;
479 
480  tmp = realloc(n->nm_nlh, newlen);
481  if (tmp == NULL)
482  return -NLE_NOMEM;
483 
484  n->nm_nlh = tmp;
485  n->nm_size = newlen;
486 
487  return 0;
488 }
489 
490 /**
491  * Add a netlink message header to a netlink message
492  * @arg n netlink message
493  * @arg pid netlink process id or NL_AUTO_PID
494  * @arg seq sequence number of message or NL_AUTO_SEQ
495  * @arg type message type
496  * @arg payload length of message payload
497  * @arg flags message flags
498  *
499  * Adds or overwrites the netlink message header in an existing message
500  * object. If \a payload is greater-than zero additional room will be
501  * reserved, f.e. for family specific headers. It can be accesed via
502  * nlmsg_data().
503  *
504  * @return A pointer to the netlink message header or NULL.
505  */
506 struct nlmsghdr *nlmsg_put(struct nl_msg *n, uint32_t pid, uint32_t seq,
507  int type, int payload, int flags)
508 {
509  struct nlmsghdr *nlh;
510 
511  if (n->nm_nlh->nlmsg_len < NLMSG_HDRLEN)
512  BUG();
513 
514  nlh = (struct nlmsghdr *) n->nm_nlh;
515  nlh->nlmsg_type = type;
516  nlh->nlmsg_flags = flags;
517  nlh->nlmsg_pid = pid;
518  nlh->nlmsg_seq = seq;
519 
520  NL_DBG(2, "msg %p: Added netlink header type=%d, flags=%d, pid=%d, "
521  "seq=%d\n", n, type, flags, pid, seq);
522 
523  if (payload > 0 &&
524  nlmsg_reserve(n, payload, NLMSG_ALIGNTO) == NULL)
525  return NULL;
526 
527  return nlh;
528 }
529 
530 /**
531  * Return actual netlink message
532  * @arg n netlink message
533  *
534  * Returns the actual netlink message casted to the type of the netlink
535  * message header.
536  *
537  * @return A pointer to the netlink message.
538  */
539 struct nlmsghdr *nlmsg_hdr(struct nl_msg *n)
540 {
541  return n->nm_nlh;
542 }
543 
544 /**
545  * Acquire a reference on a netlink message
546  * @arg msg message to acquire reference from
547  */
548 void nlmsg_get(struct nl_msg *msg)
549 {
550  msg->nm_refcnt++;
551  NL_DBG(4, "New reference to message %p, total %d\n",
552  msg, msg->nm_refcnt);
553 }
554 
555 /**
556  * Release a reference from an netlink message
557  * @arg msg message to release reference from
558  *
559  * Frees memory after the last reference has been released.
560  */
561 void nlmsg_free(struct nl_msg *msg)
562 {
563  if (!msg)
564  return;
565 
566  msg->nm_refcnt--;
567  NL_DBG(4, "Returned message reference %p, %d remaining\n",
568  msg, msg->nm_refcnt);
569 
570  if (msg->nm_refcnt < 0)
571  BUG();
572 
573  if (msg->nm_refcnt <= 0) {
574  free(msg->nm_nlh);
575  free(msg);
576  NL_DBG(2, "msg %p: Freed\n", msg);
577  }
578 }
579 
580 /** @} */
581 
582 /**
583  * @name Attributes
584  * @{
585  */
586 
587 void nlmsg_set_proto(struct nl_msg *msg, int protocol)
588 {
589  msg->nm_protocol = protocol;
590 }
591 
592 int nlmsg_get_proto(struct nl_msg *msg)
593 {
594  return msg->nm_protocol;
595 }
596 
597 size_t nlmsg_get_max_size(struct nl_msg *msg)
598 {
599  return msg->nm_size;
600 }
601 
602 void nlmsg_set_src(struct nl_msg *msg, struct sockaddr_nl *addr)
603 {
604  memcpy(&msg->nm_src, addr, sizeof(*addr));
605 }
606 
607 struct sockaddr_nl *nlmsg_get_src(struct nl_msg *msg)
608 {
609  return &msg->nm_src;
610 }
611 
612 void nlmsg_set_dst(struct nl_msg *msg, struct sockaddr_nl *addr)
613 {
614  memcpy(&msg->nm_dst, addr, sizeof(*addr));
615 }
616 
617 struct sockaddr_nl *nlmsg_get_dst(struct nl_msg *msg)
618 {
619  return &msg->nm_dst;
620 }
621 
622 void nlmsg_set_creds(struct nl_msg *msg, struct ucred *creds)
623 {
624  memcpy(&msg->nm_creds, creds, sizeof(*creds));
625  msg->nm_flags |= NL_MSG_CRED_PRESENT;
626 }
627 
628 struct ucred *nlmsg_get_creds(struct nl_msg *msg)
629 {
630  if (msg->nm_flags & NL_MSG_CRED_PRESENT)
631  return &msg->nm_creds;
632  return NULL;
633 }
634 
635 /** @} */
636 
637 /**
638  * @name Netlink Message Type Translations
639  * @{
640  */
641 
642 static const struct trans_tbl nl_msgtypes[] = {
643  __ADD(NLMSG_NOOP,NOOP)
644  __ADD(NLMSG_ERROR,ERROR)
645  __ADD(NLMSG_DONE,DONE)
646  __ADD(NLMSG_OVERRUN,OVERRUN)
647 };
648 
649 char *nl_nlmsgtype2str(int type, char *buf, size_t size)
650 {
651  return __type2str(type, buf, size, nl_msgtypes,
652  ARRAY_SIZE(nl_msgtypes));
653 }
654 
655 int nl_str2nlmsgtype(const char *name)
656 {
657  return __str2type(name, nl_msgtypes, ARRAY_SIZE(nl_msgtypes));
658 }
659 
660 /** @} */
661 
662 /**
663  * @name Netlink Message Flags Translations
664  * @{
665  */
666 
667 char *nl_nlmsg_flags2str(int flags, char *buf, size_t len)
668 {
669  memset(buf, 0, len);
670 
671 #define PRINT_FLAG(f) \
672  if (flags & NLM_F_##f) { \
673  flags &= ~NLM_F_##f; \
674  strncat(buf, #f, len - strlen(buf) - 1); \
675  if (flags) \
676  strncat(buf, ",", len - strlen(buf) - 1); \
677  }
678 
679  PRINT_FLAG(REQUEST);
680  PRINT_FLAG(MULTI);
681  PRINT_FLAG(ACK);
682  PRINT_FLAG(ECHO);
683  PRINT_FLAG(ROOT);
684  PRINT_FLAG(MATCH);
685  PRINT_FLAG(ATOMIC);
686  PRINT_FLAG(REPLACE);
687  PRINT_FLAG(EXCL);
688  PRINT_FLAG(CREATE);
689  PRINT_FLAG(APPEND);
690 
691  if (flags) {
692  char s[32];
693  snprintf(s, sizeof(s), "0x%x", flags);
694  strncat(buf, s, len - strlen(buf) - 1);
695  }
696 #undef PRINT_FLAG
697 
698  return buf;
699 }
700 
701 /** @} */
702 
703 /**
704  * @name Direct Parsing
705  * @{
706  */
707 
708 /** @cond SKIP */
709 struct dp_xdata {
710  void (*cb)(struct nl_object *, void *);
711  void *arg;
712 };
713 /** @endcond */
714 
715 static int parse_cb(struct nl_object *obj, struct nl_parser_param *p)
716 {
717  struct dp_xdata *x = p->pp_arg;
718 
719  x->cb(obj, x->arg);
720  return 0;
721 }
722 
723 int nl_msg_parse(struct nl_msg *msg, void (*cb)(struct nl_object *, void *),
724  void *arg)
725 {
726  struct nl_cache_ops *ops;
727  struct nl_parser_param p = {
728  .pp_cb = parse_cb
729  };
730  struct dp_xdata x = {
731  .cb = cb,
732  .arg = arg,
733  };
734  int err;
735 
736  ops = nl_cache_ops_associate_safe(nlmsg_get_proto(msg),
737  nlmsg_hdr(msg)->nlmsg_type);
738  if (ops == NULL)
739  return -NLE_MSGTYPE_NOSUPPORT;
740  p.pp_arg = &x;
741 
742  err = nl_cache_parse(ops, NULL, nlmsg_hdr(msg), &p);
743  nl_cache_ops_put(ops);
744 
745  return err;
746 }
747 
748 /** @} */
749 
750 /**
751  * @name Dumping
752  * @{
753  */
754 
755 static void prefix_line(FILE *ofd, int prefix)
756 {
757  int i;
758 
759  for (i = 0; i < prefix; i++)
760  fprintf(ofd, " ");
761 }
762 
763 static inline void dump_hex(FILE *ofd, char *start, int len, int prefix)
764 {
765  int i, a, c, limit;
766  char ascii[21] = {0};
767 
768  limit = 16 - (prefix * 2);
769  prefix_line(ofd, prefix);
770  fprintf(ofd, " ");
771 
772  for (i = 0, a = 0, c = 0; i < len; i++) {
773  int v = *(uint8_t *) (start + i);
774 
775  fprintf(ofd, "%02x ", v);
776  ascii[a++] = isprint(v) ? v : '.';
777 
778  if (++c >= limit) {
779  fprintf(ofd, "%s\n", ascii);
780  if (i < (len - 1)) {
781  prefix_line(ofd, prefix);
782  fprintf(ofd, " ");
783  }
784  a = c = 0;
785  memset(ascii, 0, sizeof(ascii));
786  }
787  }
788 
789  if (c != 0) {
790  for (i = 0; i < (limit - c); i++)
791  fprintf(ofd, " ");
792  fprintf(ofd, "%s\n", ascii);
793  }
794 }
795 
796 static void print_hdr(FILE *ofd, struct nl_msg *msg)
797 {
798  struct nlmsghdr *nlh = nlmsg_hdr(msg);
799  struct nl_cache_ops *ops;
800  struct nl_msgtype *mt;
801  char buf[128];
802 
803  fprintf(ofd, " .nlmsg_len = %d\n", nlh->nlmsg_len);
804 
805  ops = nl_cache_ops_associate_safe(nlmsg_get_proto(msg), nlh->nlmsg_type);
806  if (ops) {
807  mt = nl_msgtype_lookup(ops, nlh->nlmsg_type);
808  if (!mt)
809  BUG();
810 
811  snprintf(buf, sizeof(buf), "%s::%s", ops->co_name, mt->mt_name);
812  nl_cache_ops_put(ops);
813  } else
814  nl_nlmsgtype2str(nlh->nlmsg_type, buf, sizeof(buf));
815 
816  fprintf(ofd, " .type = %d <%s>\n", nlh->nlmsg_type, buf);
817  fprintf(ofd, " .flags = %d <%s>\n", nlh->nlmsg_flags,
818  nl_nlmsg_flags2str(nlh->nlmsg_flags, buf, sizeof(buf)));
819  fprintf(ofd, " .seq = %d\n", nlh->nlmsg_seq);
820  fprintf(ofd, " .port = %d\n", nlh->nlmsg_pid);
821 
822 }
823 
824 static void print_genl_hdr(FILE *ofd, void *start)
825 {
826  struct genlmsghdr *ghdr = start;
827 
828  fprintf(ofd, " [GENERIC NETLINK HEADER] %zu octets\n", GENL_HDRLEN);
829  fprintf(ofd, " .cmd = %u\n", ghdr->cmd);
830  fprintf(ofd, " .version = %u\n", ghdr->version);
831  fprintf(ofd, " .unused = %#x\n", ghdr->reserved);
832 }
833 
834 static void *print_genl_msg(struct nl_msg *msg, FILE *ofd, struct nlmsghdr *hdr,
835  struct nl_cache_ops *ops, int *payloadlen)
836 {
837  void *data = nlmsg_data(hdr);
838 
839  if (*payloadlen < GENL_HDRLEN)
840  return data;
841 
842  print_genl_hdr(ofd, data);
843 
844  *payloadlen -= GENL_HDRLEN;
845  data += GENL_HDRLEN;
846 
847  if (ops) {
848  int hdrsize = ops->co_hdrsize - GENL_HDRLEN;
849 
850  if (hdrsize > 0) {
851  if (*payloadlen < hdrsize)
852  return data;
853 
854  fprintf(ofd, " [HEADER] %d octets\n", hdrsize);
855  dump_hex(ofd, data, hdrsize, 0);
856 
857  *payloadlen -= hdrsize;
858  data += hdrsize;
859  }
860  }
861 
862  return data;
863 }
864 
865 static void dump_attr(FILE *ofd, struct nlattr *attr, int prefix)
866 {
867  int len = nla_len(attr);
868 
869  dump_hex(ofd, nla_data(attr), len, prefix);
870 }
871 
872 static void dump_attrs(FILE *ofd, struct nlattr *attrs, int attrlen,
873  int prefix)
874 {
875  int rem;
876  struct nlattr *nla;
877 
878  nla_for_each_attr(nla, attrs, attrlen, rem) {
879  int padlen, alen = nla_len(nla);
880 
881  prefix_line(ofd, prefix);
882 
883  if (nla->nla_type == 0)
884  fprintf(ofd, " [ATTR PADDING] %d octets\n", alen);
885  else
886  fprintf(ofd, " [ATTR %02d%s] %d octets\n", nla_type(nla),
887  nla_is_nested(nla) ? " NESTED" : "",
888  alen);
889 
890  if (nla_is_nested(nla))
891  dump_attrs(ofd, nla_data(nla), alen, prefix+1);
892  else
893  dump_attr(ofd, nla, prefix);
894 
895  padlen = nla_padlen(alen);
896  if (padlen > 0) {
897  prefix_line(ofd, prefix);
898  fprintf(ofd, " [PADDING] %d octets\n",
899  padlen);
900  dump_hex(ofd, nla_data(nla) + alen,
901  padlen, prefix);
902  }
903  }
904 
905  if (rem) {
906  prefix_line(ofd, prefix);
907  fprintf(ofd, " [LEFTOVER] %d octets\n", rem);
908  }
909 }
910 
911 static void dump_error_msg(struct nl_msg *msg, FILE *ofd)
912 {
913  struct nlmsghdr *hdr = nlmsg_hdr(msg);
914  struct nlmsgerr *err = nlmsg_data(hdr);
915 
916  fprintf(ofd, " [ERRORMSG] %zu octets\n", sizeof(*err));
917 
918  if (nlmsg_len(hdr) >= sizeof(*err)) {
919  char buf[256];
920  struct nl_msg *errmsg;
921 
922  fprintf(ofd, " .error = %d \"%s\"\n", err->error,
923  strerror_r(-err->error, buf, sizeof(buf)));
924  fprintf(ofd, " [ORIGINAL MESSAGE] %zu octets\n", sizeof(*hdr));
925 
926  errmsg = nlmsg_inherit(&err->msg);
927  print_hdr(ofd, errmsg);
928  nlmsg_free(errmsg);
929  }
930 }
931 
932 static void print_msg(struct nl_msg *msg, FILE *ofd, struct nlmsghdr *hdr)
933 {
934  struct nl_cache_ops *ops;
935  int payloadlen = nlmsg_len(hdr);
936  int attrlen = 0;
937  void *data;
938 
939  data = nlmsg_data(hdr);
940  ops = nl_cache_ops_associate_safe(nlmsg_get_proto(msg),
941  hdr->nlmsg_type);
942  if (ops) {
943  attrlen = nlmsg_attrlen(hdr, ops->co_hdrsize);
944  payloadlen -= attrlen;
945  }
946 
947  if (msg->nm_protocol == NETLINK_GENERIC)
948  data = print_genl_msg(msg, ofd, hdr, ops, &payloadlen);
949 
950  if (payloadlen) {
951  fprintf(ofd, " [PAYLOAD] %d octets\n", payloadlen);
952  dump_hex(ofd, data, payloadlen, 0);
953  }
954 
955  if (attrlen) {
956  struct nlattr *attrs;
957  int attrlen;
958 
959  attrs = nlmsg_attrdata(hdr, ops->co_hdrsize);
960  attrlen = nlmsg_attrlen(hdr, ops->co_hdrsize);
961  dump_attrs(ofd, attrs, attrlen, 0);
962  }
963 
964  if (ops)
965  nl_cache_ops_put(ops);
966 }
967 
968 /**
969  * Dump message in human readable format to file descriptor
970  * @arg msg Message to print
971  * @arg ofd File descriptor.
972  */
973 void nl_msg_dump(struct nl_msg *msg, FILE *ofd)
974 {
975  struct nlmsghdr *hdr = nlmsg_hdr(msg);
976 
977  fprintf(ofd,
978  "-------------------------- BEGIN NETLINK MESSAGE ---------------------------\n");
979 
980  fprintf(ofd, " [NETLINK HEADER] %zu octets\n", sizeof(struct nlmsghdr));
981  print_hdr(ofd, msg);
982 
983  if (hdr->nlmsg_type == NLMSG_ERROR)
984  dump_error_msg(msg, ofd);
985  else if (nlmsg_len(hdr) > 0)
986  print_msg(msg, ofd, hdr);
987 
988  fprintf(ofd,
989  "--------------------------- END NETLINK MESSAGE ---------------------------\n");
990 }
991 
992 /** @} */
993 
994 /** @} */