libnl  3.6.0
msg.c
1 /* SPDX-License-Identifier: LGPL-2.1-only */
2 /*
3  * Copyright (c) 2003-2012 Thomas Graf <tgraf@suug.ch>
4  */
5 
6 /**
7  * @ingroup core
8  * @defgroup msg Message Construction & Parsing
9  * Netlink Message Construction/Parsing Interface
10  *
11  * Related sections in the development guide:
12  * - @core_doc{_message_parsing_amp_construction,Message Parsing & Construction}
13  *
14  * @{
15  *
16  * Header
17  * ------
18  * ~~~~{.c}
19  * #include <netlink/msg.h>
20  * ~~~~
21  */
22 
23 #include <netlink-private/netlink.h>
24 #include <netlink-private/utils.h>
25 #include <netlink/netlink.h>
26 #include <netlink/utils.h>
27 #include <netlink/cache.h>
28 #include <netlink/attr.h>
29 #include <linux/socket.h>
30 
31 static size_t default_msg_size;
32 
33 static void __init init_msg_size(void)
34 {
35  default_msg_size = getpagesize();
36 }
37 
38 /**
39  * @name Size Calculations
40  * @{
41  */
42 
43 /**
44  * Calculates size of netlink message based on payload length.
45  * @arg payload Length of payload
46  *
47  * @return size of netlink message without padding.
48  */
49 int nlmsg_size(int payload)
50 {
51  return NLMSG_HDRLEN + payload;
52 }
53 
54 static int nlmsg_msg_size(int payload)
55 {
56  return nlmsg_size(payload);
57 }
58 
59 /**
60  * Calculates size of netlink message including padding based on payload length
61  * @arg payload Length of payload
62  *
63  * This function is idential to nlmsg_size() + nlmsg_padlen().
64  *
65  * @return Size of netlink message including padding.
66  */
67 int nlmsg_total_size(int payload)
68 {
69  return NLMSG_ALIGN(nlmsg_msg_size(payload));
70 }
71 
72 /**
73  * Size of padding that needs to be added at end of message
74  * @arg payload Length of payload
75  *
76  * Calculates the number of bytes of padding which is required to be added to
77  * the end of the message to ensure that the next netlink message header begins
78  * properly aligned to NLMSG_ALIGNTO.
79  *
80  * @return Number of bytes of padding needed.
81  */
82 int nlmsg_padlen(int payload)
83 {
84  return nlmsg_total_size(payload) - nlmsg_msg_size(payload);
85 }
86 
87 /** @} */
88 
89 /**
90  * @name Access to Message Payload
91  * @{
92  */
93 
94 /**
95  * Return pointer to message payload
96  * @arg nlh Netlink message header
97  *
98  * @return Pointer to start of message payload.
99  */
100 void *nlmsg_data(const struct nlmsghdr *nlh)
101 {
102  return (unsigned char *) nlh + NLMSG_HDRLEN;
103 }
104 
105 void *nlmsg_tail(const struct nlmsghdr *nlh)
106 {
107  return (unsigned char *) nlh + NLMSG_ALIGN(nlh->nlmsg_len);
108 }
109 
110 /**
111  * Return length of message payload
112  * @arg nlh Netlink message header
113  *
114  * @return Length of message payload in bytes.
115  */
116 int nlmsg_datalen(const struct nlmsghdr *nlh)
117 {
118  return nlh->nlmsg_len - NLMSG_HDRLEN;
119 }
120 
121 static int nlmsg_len(const struct nlmsghdr *nlh)
122 {
123  return nlmsg_datalen(nlh);
124 }
125 
126 /** @} */
127 
128 /**
129  * @name Attribute Access
130  * @{
131  */
132 
133 /**
134  * head of attributes data
135  * @arg nlh netlink message header
136  * @arg hdrlen length of family specific header
137  */
138 struct nlattr *nlmsg_attrdata(const struct nlmsghdr *nlh, int hdrlen)
139 {
140  unsigned char *data = nlmsg_data(nlh);
141  return (struct nlattr *) (data + NLMSG_ALIGN(hdrlen));
142 }
143 
144 /**
145  * length of attributes data
146  * @arg nlh netlink message header
147  * @arg hdrlen length of family specific header
148  */
149 int nlmsg_attrlen(const struct nlmsghdr *nlh, int hdrlen)
150 {
151  return max_t(int, nlmsg_len(nlh) - NLMSG_ALIGN(hdrlen), 0);
152 }
153 
154 /** @} */
155 
156 /**
157  * @name Message Parsing
158  * @{
159  */
160 
161 int nlmsg_valid_hdr(const struct nlmsghdr *nlh, int hdrlen)
162 {
163  if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
164  return 0;
165 
166  return 1;
167 }
168 
169 /**
170  * check if the netlink message fits into the remaining bytes
171  * @arg nlh netlink message header
172  * @arg remaining number of bytes remaining in message stream
173  */
174 int nlmsg_ok(const struct nlmsghdr *nlh, int remaining)
175 {
176  return (remaining >= (int)sizeof(struct nlmsghdr) &&
177  nlh->nlmsg_len >= sizeof(struct nlmsghdr) &&
178  nlh->nlmsg_len <= remaining);
179 }
180 
181 /**
182  * next netlink message in message stream
183  * @arg nlh netlink message header
184  * @arg remaining number of bytes remaining in message stream
185  *
186  * @returns the next netlink message in the message stream and
187  * decrements remaining by the size of the current message.
188  */
189 struct nlmsghdr *nlmsg_next(struct nlmsghdr *nlh, int *remaining)
190 {
191  int totlen = NLMSG_ALIGN(nlh->nlmsg_len);
192 
193  *remaining -= totlen;
194 
195  return (struct nlmsghdr *) ((unsigned char *) nlh + totlen);
196 }
197 
198 /**
199  * parse attributes of a netlink message
200  * @arg nlh netlink message header
201  * @arg hdrlen length of family specific header
202  * @arg tb destination array with maxtype+1 elements
203  * @arg maxtype maximum attribute type to be expected
204  * @arg policy validation policy
205  *
206  * See nla_parse()
207  */
208 int nlmsg_parse(struct nlmsghdr *nlh, int hdrlen, struct nlattr *tb[],
209  int maxtype, const struct nla_policy *policy)
210 {
211  if (!nlmsg_valid_hdr(nlh, hdrlen))
212  return -NLE_MSG_TOOSHORT;
213 
214  return nla_parse(tb, maxtype, nlmsg_attrdata(nlh, hdrlen),
215  nlmsg_attrlen(nlh, hdrlen), policy);
216 }
217 
218 /**
219  * nlmsg_find_attr - find a specific attribute in a netlink message
220  * @arg nlh netlink message header
221  * @arg hdrlen length of familiy specific header
222  * @arg attrtype type of attribute to look for
223  *
224  * Returns the first attribute which matches the specified type.
225  */
226 struct nlattr *nlmsg_find_attr(struct nlmsghdr *nlh, int hdrlen, int attrtype)
227 {
228  return nla_find(nlmsg_attrdata(nlh, hdrlen),
229  nlmsg_attrlen(nlh, hdrlen), attrtype);
230 }
231 
232 /**
233  * nlmsg_validate - validate a netlink message including attributes
234  * @arg nlh netlinket message header
235  * @arg hdrlen length of familiy specific header
236  * @arg maxtype maximum attribute type to be expected
237  * @arg policy validation policy
238  */
239 int nlmsg_validate(struct nlmsghdr *nlh, int hdrlen, int maxtype,
240  const struct nla_policy *policy)
241 {
242  if (!nlmsg_valid_hdr(nlh, hdrlen))
243  return -NLE_MSG_TOOSHORT;
244 
245  return nla_validate(nlmsg_attrdata(nlh, hdrlen),
246  nlmsg_attrlen(nlh, hdrlen), maxtype, policy);
247 }
248 
249 /** @} */
250 
251 /**
252  * @name Message Building/Access
253  * @{
254  */
255 
256 static struct nl_msg *__nlmsg_alloc(size_t len)
257 {
258  struct nl_msg *nm;
259 
260  if (len < sizeof(struct nlmsghdr))
261  len = sizeof(struct nlmsghdr);
262 
263  nm = calloc(1, sizeof(*nm));
264  if (!nm)
265  goto errout;
266 
267  nm->nm_refcnt = 1;
268 
269  nm->nm_nlh = calloc(1, len);
270  if (!nm->nm_nlh)
271  goto errout;
272 
273  nm->nm_protocol = -1;
274  nm->nm_size = len;
275  nm->nm_nlh->nlmsg_len = nlmsg_total_size(0);
276 
277  NL_DBG(2, "msg %p: Allocated new message, maxlen=%zu\n", nm, len);
278 
279  return nm;
280 errout:
281  free(nm);
282  return NULL;
283 }
284 
285 /**
286  * Allocate a new netlink message with the default maximum payload size.
287  *
288  * Allocates a new netlink message without any further payload. The
289  * maximum payload size defaults to PAGESIZE or as otherwise specified
290  * with nlmsg_set_default_size().
291  *
292  * @return Newly allocated netlink message or NULL.
293  */
294 struct nl_msg *nlmsg_alloc(void)
295 {
296  return __nlmsg_alloc(default_msg_size);
297 }
298 
299 /**
300  * Allocate a new netlink message with maximum payload size specified.
301  */
302 struct nl_msg *nlmsg_alloc_size(size_t max)
303 {
304  return __nlmsg_alloc(max);
305 }
306 
307 /**
308  * Allocate a new netlink message and inherit netlink message header
309  * @arg hdr Netlink message header template
310  *
311  * Allocates a new netlink message and inherits the original message
312  * header. If \a hdr is not NULL it will be used as a template for
313  * the netlink message header, otherwise the header is left blank.
314  *
315  * @return Newly allocated netlink message or NULL
316  */
317 struct nl_msg *nlmsg_inherit(struct nlmsghdr *hdr)
318 {
319  struct nl_msg *nm;
320 
321  nm = nlmsg_alloc();
322  if (nm && hdr) {
323  struct nlmsghdr *new = nm->nm_nlh;
324 
325  new->nlmsg_type = hdr->nlmsg_type;
326  new->nlmsg_flags = hdr->nlmsg_flags;
327  new->nlmsg_seq = hdr->nlmsg_seq;
328  new->nlmsg_pid = hdr->nlmsg_pid;
329  }
330 
331  return nm;
332 }
333 
334 /**
335  * Allocate a new netlink message
336  * @arg nlmsgtype Netlink message type
337  * @arg flags Message flags.
338  *
339  * @return Newly allocated netlink message or NULL.
340  */
341 struct nl_msg *nlmsg_alloc_simple(int nlmsgtype, int flags)
342 {
343  struct nl_msg *msg;
344  struct nlmsghdr nlh = {
345  .nlmsg_type = nlmsgtype,
346  .nlmsg_flags = flags,
347  .nlmsg_seq = NL_AUTO_SEQ,
348  .nlmsg_pid = NL_AUTO_PID,
349  };
350 
351  msg = nlmsg_inherit(&nlh);
352  if (msg)
353  NL_DBG(2, "msg %p: Allocated new simple message\n", msg);
354 
355  return msg;
356 }
357 
358 /**
359  * Set the default maximum message payload size for allocated messages
360  * @arg max Size of payload in bytes.
361  */
362 void nlmsg_set_default_size(size_t max)
363 {
364  if (max < nlmsg_total_size(0))
365  max = nlmsg_total_size(0);
366 
367  default_msg_size = max;
368 }
369 
370 /**
371  * Convert a netlink message received from a netlink socket to a nl_msg
372  * @arg hdr Netlink message received from netlink socket.
373  *
374  * Allocates a new netlink message and copies all of the data pointed to
375  * by \a hdr into the new message object.
376  *
377  * @return Newly allocated netlink message or NULL.
378  */
379 struct nl_msg *nlmsg_convert(struct nlmsghdr *hdr)
380 {
381  struct nl_msg *nm;
382 
383  nm = __nlmsg_alloc(NLMSG_ALIGN(hdr->nlmsg_len));
384  if (!nm)
385  return NULL;
386 
387  memcpy(nm->nm_nlh, hdr, hdr->nlmsg_len);
388 
389  return nm;
390 }
391 
392 /**
393  * Reserve room for additional data in a netlink message
394  * @arg n netlink message
395  * @arg len length of additional data to reserve room for
396  * @arg pad number of bytes to align data to
397  *
398  * Reserves room for additional data at the tail of the an
399  * existing netlink message. Eventual padding required will
400  * be zeroed out.
401  *
402  * @return Pointer to start of additional data tailroom or NULL.
403  */
404 void *nlmsg_reserve(struct nl_msg *n, size_t len, int pad)
405 {
406  char *buf = (char *) n->nm_nlh;
407  size_t nlmsg_len = n->nm_nlh->nlmsg_len;
408  size_t tlen;
409 
410  if (len > n->nm_size)
411  return NULL;
412 
413  tlen = pad ? ((len + (pad - 1)) & ~(pad - 1)) : len;
414 
415  if ((tlen + nlmsg_len) > n->nm_size)
416  return NULL;
417 
418  buf += nlmsg_len;
419  n->nm_nlh->nlmsg_len += tlen;
420 
421  if (tlen > len)
422  memset(buf + len, 0, tlen - len);
423 
424  NL_DBG(2, "msg %p: Reserved %zu (%zu) bytes, pad=%d, nlmsg_len=%d\n",
425  n, tlen, len, pad, n->nm_nlh->nlmsg_len);
426 
427  return buf;
428 }
429 
430 /**
431  * Append data to tail of a netlink message
432  * @arg n netlink message
433  * @arg data data to add
434  * @arg len length of data
435  * @arg pad Number of bytes to align data to.
436  *
437  * Extends the netlink message as needed and appends the data of given
438  * length to the message.
439  *
440  * @return 0 on success or a negative error code
441  */
442 int nlmsg_append(struct nl_msg *n, void *data, size_t len, int pad)
443 {
444  void *tmp;
445 
446  tmp = nlmsg_reserve(n, len, pad);
447  if (tmp == NULL)
448  return -NLE_NOMEM;
449 
450  memcpy(tmp, data, len);
451  NL_DBG(2, "msg %p: Appended %zu bytes with padding %d\n", n, len, pad);
452 
453  return 0;
454 }
455 
456 /**
457  * Expand maximum payload size of a netlink message
458  * @arg n Netlink message.
459  * @arg newlen New maximum payload size.
460  *
461  * Reallocates the payload section of a netlink message and increases
462  * the maximum payload size of the message.
463  *
464  * @note Any pointers pointing to old payload block will be stale and
465  * need to be refetched. Therfore, do not expand while constructing
466  * nested attributes or while reserved data blocks are held.
467  *
468  * @return 0 on success or a negative error code.
469  */
470 int nlmsg_expand(struct nl_msg *n, size_t newlen)
471 {
472  void *tmp;
473 
474  if (newlen <= n->nm_size)
475  return -NLE_INVAL;
476 
477  tmp = realloc(n->nm_nlh, newlen);
478  if (tmp == NULL)
479  return -NLE_NOMEM;
480 
481  n->nm_nlh = tmp;
482  n->nm_size = newlen;
483 
484  return 0;
485 }
486 
487 /**
488  * Add a netlink message header to a netlink message
489  * @arg n netlink message
490  * @arg pid netlink process id or NL_AUTO_PID
491  * @arg seq sequence number of message or NL_AUTO_SEQ
492  * @arg type message type
493  * @arg payload length of message payload
494  * @arg flags message flags
495  *
496  * Adds or overwrites the netlink message header in an existing message
497  * object. If \a payload is greater-than zero additional room will be
498  * reserved, f.e. for family specific headers. It can be accesed via
499  * nlmsg_data().
500  *
501  * @return A pointer to the netlink message header or NULL.
502  */
503 struct nlmsghdr *nlmsg_put(struct nl_msg *n, uint32_t pid, uint32_t seq,
504  int type, int payload, int flags)
505 {
506  struct nlmsghdr *nlh;
507 
508  if (n->nm_nlh->nlmsg_len < NLMSG_HDRLEN)
509  BUG();
510 
511  nlh = (struct nlmsghdr *) n->nm_nlh;
512  nlh->nlmsg_type = type;
513  nlh->nlmsg_flags = flags;
514  nlh->nlmsg_pid = pid;
515  nlh->nlmsg_seq = seq;
516 
517  NL_DBG(2, "msg %p: Added netlink header type=%d, flags=%d, pid=%d, "
518  "seq=%d\n", n, type, flags, pid, seq);
519 
520  if (payload > 0 &&
521  nlmsg_reserve(n, payload, NLMSG_ALIGNTO) == NULL)
522  return NULL;
523 
524  return nlh;
525 }
526 
527 /**
528  * Return actual netlink message
529  * @arg n netlink message
530  *
531  * Returns the actual netlink message casted to the type of the netlink
532  * message header.
533  *
534  * @return A pointer to the netlink message.
535  */
536 struct nlmsghdr *nlmsg_hdr(struct nl_msg *n)
537 {
538  return n->nm_nlh;
539 }
540 
541 /**
542  * Acquire a reference on a netlink message
543  * @arg msg message to acquire reference from
544  */
545 void nlmsg_get(struct nl_msg *msg)
546 {
547  msg->nm_refcnt++;
548  NL_DBG(4, "New reference to message %p, total %d\n",
549  msg, msg->nm_refcnt);
550 }
551 
552 /**
553  * Release a reference from an netlink message
554  * @arg msg message to release reference from
555  *
556  * Frees memory after the last reference has been released.
557  */
558 void nlmsg_free(struct nl_msg *msg)
559 {
560  if (!msg)
561  return;
562 
563  msg->nm_refcnt--;
564  NL_DBG(4, "Returned message reference %p, %d remaining\n",
565  msg, msg->nm_refcnt);
566 
567  if (msg->nm_refcnt < 0)
568  BUG();
569 
570  if (msg->nm_refcnt <= 0) {
571  free(msg->nm_nlh);
572  NL_DBG(2, "msg %p: Freed\n", msg);
573  free(msg);
574  }
575 }
576 
577 /** @} */
578 
579 /**
580  * @name Attributes
581  * @{
582  */
583 
584 void nlmsg_set_proto(struct nl_msg *msg, int protocol)
585 {
586  msg->nm_protocol = protocol;
587 }
588 
589 int nlmsg_get_proto(struct nl_msg *msg)
590 {
591  return msg->nm_protocol;
592 }
593 
594 size_t nlmsg_get_max_size(struct nl_msg *msg)
595 {
596  return msg->nm_size;
597 }
598 
599 void nlmsg_set_src(struct nl_msg *msg, struct sockaddr_nl *addr)
600 {
601  memcpy(&msg->nm_src, addr, sizeof(*addr));
602 }
603 
604 struct sockaddr_nl *nlmsg_get_src(struct nl_msg *msg)
605 {
606  return &msg->nm_src;
607 }
608 
609 void nlmsg_set_dst(struct nl_msg *msg, struct sockaddr_nl *addr)
610 {
611  memcpy(&msg->nm_dst, addr, sizeof(*addr));
612 }
613 
614 struct sockaddr_nl *nlmsg_get_dst(struct nl_msg *msg)
615 {
616  return &msg->nm_dst;
617 }
618 
619 void nlmsg_set_creds(struct nl_msg *msg, struct ucred *creds)
620 {
621  memcpy(&msg->nm_creds, creds, sizeof(*creds));
622  msg->nm_flags |= NL_MSG_CRED_PRESENT;
623 }
624 
625 struct ucred *nlmsg_get_creds(struct nl_msg *msg)
626 {
627  if (msg->nm_flags & NL_MSG_CRED_PRESENT)
628  return &msg->nm_creds;
629  return NULL;
630 }
631 
632 /** @} */
633 
634 /**
635  * @name Netlink Message Type Translations
636  * @{
637  */
638 
639 static const struct trans_tbl nl_msgtypes[] = {
640  __ADD(NLMSG_NOOP,NOOP),
641  __ADD(NLMSG_ERROR,ERROR),
642  __ADD(NLMSG_DONE,DONE),
643  __ADD(NLMSG_OVERRUN,OVERRUN),
644 };
645 
646 char *nl_nlmsgtype2str(int type, char *buf, size_t size)
647 {
648  return __type2str(type, buf, size, nl_msgtypes,
649  ARRAY_SIZE(nl_msgtypes));
650 }
651 
652 int nl_str2nlmsgtype(const char *name)
653 {
654  return __str2type(name, nl_msgtypes, ARRAY_SIZE(nl_msgtypes));
655 }
656 
657 /** @} */
658 
659 /**
660  * @name Netlink Message Flags Translations
661  * @{
662  */
663 
664 char *nl_nlmsg_flags2str(int flags, char *buf, size_t len)
665 {
666  memset(buf, 0, len);
667 
668 #define PRINT_FLAG(f) \
669  if (flags & NLM_F_##f) { \
670  flags &= ~NLM_F_##f; \
671  strncat(buf, #f, len - strlen(buf) - 1); \
672  if (flags) \
673  strncat(buf, ",", len - strlen(buf) - 1); \
674  }
675 
676  PRINT_FLAG(REQUEST);
677  PRINT_FLAG(MULTI);
678  PRINT_FLAG(ACK);
679  PRINT_FLAG(ECHO);
680  PRINT_FLAG(ROOT);
681  PRINT_FLAG(MATCH);
682  PRINT_FLAG(ATOMIC);
683  PRINT_FLAG(REPLACE);
684  PRINT_FLAG(EXCL);
685  PRINT_FLAG(CREATE);
686  PRINT_FLAG(APPEND);
687 
688  if (flags) {
689  char s[32];
690  snprintf(s, sizeof(s), "0x%x", flags);
691  strncat(buf, s, len - strlen(buf) - 1);
692  }
693 #undef PRINT_FLAG
694 
695  return buf;
696 }
697 
698 /** @} */
699 
700 /**
701  * @name Direct Parsing
702  * @{
703  */
704 
705 /** @cond SKIP */
706 struct dp_xdata {
707  void (*cb)(struct nl_object *, void *);
708  void *arg;
709 };
710 /** @endcond */
711 
712 static int parse_cb(struct nl_object *obj, struct nl_parser_param *p)
713 {
714  struct dp_xdata *x = p->pp_arg;
715 
716  x->cb(obj, x->arg);
717  return 0;
718 }
719 
720 int nl_msg_parse(struct nl_msg *msg, void (*cb)(struct nl_object *, void *),
721  void *arg)
722 {
723  struct nl_cache_ops *ops;
724  struct nl_parser_param p = {
725  .pp_cb = parse_cb
726  };
727  struct dp_xdata x = {
728  .cb = cb,
729  .arg = arg,
730  };
731  int err;
732 
733  ops = nl_cache_ops_associate_safe(nlmsg_get_proto(msg),
734  nlmsg_hdr(msg)->nlmsg_type);
735  if (ops == NULL)
736  return -NLE_MSGTYPE_NOSUPPORT;
737  p.pp_arg = &x;
738 
739  err = nl_cache_parse(ops, NULL, nlmsg_hdr(msg), &p);
740  nl_cache_ops_put(ops);
741 
742  return err;
743 }
744 
745 /** @} */
746 
747 /**
748  * @name Dumping
749  * @{
750  */
751 
752 static void prefix_line(FILE *ofd, int prefix)
753 {
754  int i;
755 
756  for (i = 0; i < prefix; i++)
757  fprintf(ofd, " ");
758 }
759 
760 static inline void dump_hex(FILE *ofd, char *start, int len, int prefix)
761 {
762  int i, a, c, limit;
763  char ascii[21] = {0};
764 
765  limit = 16 - (prefix * 2);
766  prefix_line(ofd, prefix);
767  fprintf(ofd, " ");
768 
769  for (i = 0, a = 0, c = 0; i < len; i++) {
770  int v = *(uint8_t *) (start + i);
771 
772  fprintf(ofd, "%02x ", v);
773  ascii[a++] = isprint(v) ? v : '.';
774 
775  if (++c >= limit) {
776  fprintf(ofd, "%s\n", ascii);
777  if (i < (len - 1)) {
778  prefix_line(ofd, prefix);
779  fprintf(ofd, " ");
780  }
781  a = c = 0;
782  memset(ascii, 0, sizeof(ascii));
783  }
784  }
785 
786  if (c != 0) {
787  for (i = 0; i < (limit - c); i++)
788  fprintf(ofd, " ");
789  fprintf(ofd, "%s\n", ascii);
790  }
791 }
792 
793 static void print_hdr(FILE *ofd, struct nl_msg *msg)
794 {
795  struct nlmsghdr *nlh = nlmsg_hdr(msg);
796  struct nl_cache_ops *ops;
797  struct nl_msgtype *mt;
798  char buf[128];
799 
800  fprintf(ofd, " .nlmsg_len = %d\n", nlh->nlmsg_len);
801 
802  ops = nl_cache_ops_associate_safe(nlmsg_get_proto(msg), nlh->nlmsg_type);
803  if (ops) {
804  mt = nl_msgtype_lookup(ops, nlh->nlmsg_type);
805  if (!mt)
806  BUG();
807 
808  snprintf(buf, sizeof(buf), "%s::%s", ops->co_name, mt->mt_name);
809  nl_cache_ops_put(ops);
810  } else
811  nl_nlmsgtype2str(nlh->nlmsg_type, buf, sizeof(buf));
812 
813  fprintf(ofd, " .type = %d <%s>\n", nlh->nlmsg_type, buf);
814  fprintf(ofd, " .flags = %d <%s>\n", nlh->nlmsg_flags,
815  nl_nlmsg_flags2str(nlh->nlmsg_flags, buf, sizeof(buf)));
816  fprintf(ofd, " .seq = %d\n", nlh->nlmsg_seq);
817  fprintf(ofd, " .port = %d\n", nlh->nlmsg_pid);
818 
819 }
820 
821 static void print_genl_hdr(FILE *ofd, void *start)
822 {
823  struct genlmsghdr *ghdr = start;
824 
825  fprintf(ofd, " [GENERIC NETLINK HEADER] %zu octets\n", GENL_HDRLEN);
826  fprintf(ofd, " .cmd = %u\n", ghdr->cmd);
827  fprintf(ofd, " .version = %u\n", ghdr->version);
828  fprintf(ofd, " .unused = %#x\n", ghdr->reserved);
829 }
830 
831 static void *print_genl_msg(struct nl_msg *msg, FILE *ofd, struct nlmsghdr *hdr,
832  struct nl_cache_ops *ops, int *payloadlen)
833 {
834  char *data = nlmsg_data(hdr);
835 
836  if (*payloadlen < GENL_HDRLEN)
837  return data;
838 
839  print_genl_hdr(ofd, data);
840 
841  *payloadlen -= GENL_HDRLEN;
842  data += GENL_HDRLEN;
843 
844  if (ops) {
845  int hdrsize = ops->co_hdrsize - GENL_HDRLEN;
846 
847  if (hdrsize > 0) {
848  if (*payloadlen < hdrsize)
849  return data;
850 
851  fprintf(ofd, " [HEADER] %d octets\n", hdrsize);
852  dump_hex(ofd, data, hdrsize, 0);
853 
854  *payloadlen -= hdrsize;
855  data += hdrsize;
856  }
857  }
858 
859  return data;
860 }
861 
862 static void dump_attr(FILE *ofd, struct nlattr *attr, int prefix)
863 {
864  int len = nla_len(attr);
865 
866  dump_hex(ofd, nla_data(attr), len, prefix);
867 }
868 
869 static void dump_attrs(FILE *ofd, struct nlattr *attrs, int attrlen,
870  int prefix)
871 {
872  int rem;
873  struct nlattr *nla;
874 
875  nla_for_each_attr(nla, attrs, attrlen, rem) {
876  int padlen, alen = nla_len(nla);
877 
878  prefix_line(ofd, prefix);
879 
880  if (nla->nla_type == 0)
881  fprintf(ofd, " [ATTR PADDING] %d octets\n", alen);
882  else
883  fprintf(ofd, " [ATTR %02d%s] %d octets\n", nla_type(nla),
884  nla_is_nested(nla) ? " NESTED" : "",
885  alen);
886 
887  if (nla_is_nested(nla))
888  dump_attrs(ofd, nla_data(nla), alen, prefix+1);
889  else
890  dump_attr(ofd, nla, prefix);
891 
892  padlen = nla_padlen(alen);
893  if (padlen > 0) {
894  prefix_line(ofd, prefix);
895  fprintf(ofd, " [PADDING] %d octets\n",
896  padlen);
897  dump_hex(ofd, (char *) nla_data(nla) + alen,
898  padlen, prefix);
899  }
900  }
901 
902  if (rem) {
903  prefix_line(ofd, prefix);
904  fprintf(ofd, " [LEFTOVER] %d octets\n", rem);
905  }
906 }
907 
908 static void dump_error_msg(struct nl_msg *msg, FILE *ofd)
909 {
910  struct nlmsghdr *hdr = nlmsg_hdr(msg);
911  struct nlmsgerr *err = nlmsg_data(hdr);
912 
913  fprintf(ofd, " [ERRORMSG] %zu octets\n", sizeof(*err));
914 
915  if (nlmsg_len(hdr) >= sizeof(*err)) {
916  struct nl_msg *errmsg;
917 
918  fprintf(ofd, " .error = %d \"%s\"\n", err->error,
919  nl_strerror_l(-err->error));
920  fprintf(ofd, " [ORIGINAL MESSAGE] %zu octets\n", sizeof(*hdr));
921 
922  errmsg = nlmsg_inherit(&err->msg);
923  print_hdr(ofd, errmsg);
924  nlmsg_free(errmsg);
925  }
926 }
927 
928 static void print_msg(struct nl_msg *msg, FILE *ofd, struct nlmsghdr *hdr)
929 {
930  struct nl_cache_ops *ops;
931  int payloadlen = nlmsg_len(hdr);
932  int attrlen = 0;
933  void *data;
934 
935  data = nlmsg_data(hdr);
936  ops = nl_cache_ops_associate_safe(nlmsg_get_proto(msg),
937  hdr->nlmsg_type);
938  if (ops) {
939  attrlen = nlmsg_attrlen(hdr, ops->co_hdrsize);
940  payloadlen -= attrlen;
941  }
942 
943  if (msg->nm_protocol == NETLINK_GENERIC)
944  data = print_genl_msg(msg, ofd, hdr, ops, &payloadlen);
945 
946  if (payloadlen) {
947  fprintf(ofd, " [PAYLOAD] %d octets\n", payloadlen);
948  dump_hex(ofd, data, payloadlen, 0);
949  }
950 
951  if (attrlen) {
952  struct nlattr *attrs;
953  int attrlen;
954 
955  attrs = nlmsg_attrdata(hdr, ops->co_hdrsize);
956  attrlen = nlmsg_attrlen(hdr, ops->co_hdrsize);
957  dump_attrs(ofd, attrs, attrlen, 0);
958  }
959 
960  if (ops)
961  nl_cache_ops_put(ops);
962 }
963 
964 /**
965  * Dump message in human readable format to file descriptor
966  * @arg msg Message to print
967  * @arg ofd File descriptor.
968  */
969 void nl_msg_dump(struct nl_msg *msg, FILE *ofd)
970 {
971  struct nlmsghdr *hdr = nlmsg_hdr(msg);
972 
973  fprintf(ofd,
974  "-------------------------- BEGIN NETLINK MESSAGE ---------------------------\n");
975 
976  fprintf(ofd, " [NETLINK HEADER] %zu octets\n", sizeof(struct nlmsghdr));
977  print_hdr(ofd, msg);
978 
979  if (hdr->nlmsg_type == NLMSG_ERROR)
980  dump_error_msg(msg, ofd);
981  else if (nlmsg_len(hdr) > 0)
982  print_msg(msg, ofd, hdr);
983 
984  fprintf(ofd,
985  "--------------------------- END NETLINK MESSAGE ---------------------------\n");
986 }
987 
988 /** @} */
989 
990 /** @} */
int nla_validate(const struct nlattr *head, int len, int maxtype, const struct nla_policy *policy)
Validate a stream of attributes.
Definition: attr.c:287
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:236
int nla_type(const struct nlattr *nla)
Return type of the attribute.
Definition: attr.c:103
struct nlattr * nla_find(const struct nlattr *head, int len, int attrtype)
Find a single attribute in a stream of attributes.
Definition: attr.c:316
int nla_is_nested(const struct nlattr *attr)
Return true if attribute has NLA_F_NESTED flag set.
Definition: attr.c:1025
#define nla_for_each_attr(pos, head, len, rem)
Iterate over a stream of attributes.
Definition: attr.h:312
int nla_len(const struct nlattr *nla)
Return length of the payload .
Definition: attr.c:125
int nla_padlen(int payload)
Return length of padding at the tail of the attribute.
Definition: attr.c:85
void * nla_data(const struct nlattr *nla)
Return pointer to the payload section.
Definition: attr.c:114
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:158
struct nl_msgtype * nl_msgtype_lookup(struct nl_cache_ops *ops, int msgtype)
Lookup message type cache association.
Definition: cache_mngt.c:183
void nl_cache_ops_put(struct nl_cache_ops *ops)
Decrement reference counter.
Definition: cache_mngt.c:59
int nlmsg_ok(const struct nlmsghdr *nlh, int remaining)
check if the netlink message fits into the remaining bytes
Definition: msg.c:174
void nl_msg_dump(struct nl_msg *msg, FILE *ofd)
Dump message in human readable format to file descriptor.
Definition: msg.c:969
int nlmsg_total_size(int payload)
Calculates size of netlink message including padding based on payload length.
Definition: msg.c:67
struct nl_msg * nlmsg_alloc_size(size_t max)
Allocate a new netlink message with maximum payload size specified.
Definition: msg.c:302
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:503
struct nlattr * nlmsg_attrdata(const struct nlmsghdr *nlh, int hdrlen)
head of attributes data
Definition: msg.c:138
void * nlmsg_reserve(struct nl_msg *n, size_t len, int pad)
Reserve room for additional data in a netlink message.
Definition: msg.c:404
struct nl_msg * nlmsg_convert(struct nlmsghdr *hdr)
Convert a netlink message received from a netlink socket to a nl_msg.
Definition: msg.c:379
void nlmsg_get(struct nl_msg *msg)
Acquire a reference on a netlink message.
Definition: msg.c:545
struct nl_msg * nlmsg_alloc_simple(int nlmsgtype, int flags)
Allocate a new netlink message.
Definition: msg.c:341
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:239
void nlmsg_free(struct nl_msg *msg)
Release a reference from an netlink message.
Definition: msg.c:558
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:208
int nlmsg_expand(struct nl_msg *n, size_t newlen)
Expand maximum payload size of a netlink message.
Definition: msg.c:470
struct nl_msg * nlmsg_alloc(void)
Allocate a new netlink message with the default maximum payload size.
Definition: msg.c:294
struct nlmsghdr * nlmsg_hdr(struct nl_msg *n)
Return actual netlink message.
Definition: msg.c:536
int nlmsg_datalen(const struct nlmsghdr *nlh)
Return length of message payload.
Definition: msg.c:116
struct nl_msg * nlmsg_inherit(struct nlmsghdr *hdr)
Allocate a new netlink message and inherit netlink message header.
Definition: msg.c:317
int nlmsg_attrlen(const struct nlmsghdr *nlh, int hdrlen)
length of attributes data
Definition: msg.c:149
void nlmsg_set_default_size(size_t max)
Set the default maximum message payload size for allocated messages.
Definition: msg.c:362
#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:40
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:442
int nlmsg_padlen(int payload)
Size of padding that needs to be added at end of message.
Definition: msg.c:82
void * nlmsg_data(const struct nlmsghdr *nlh)
Return pointer to message payload.
Definition: msg.c:100
int nlmsg_size(int payload)
Calculates size of netlink message based on payload length.
Definition: msg.c:49
struct nlmsghdr * nlmsg_next(struct nlmsghdr *nlh, int *remaining)
next netlink message in message stream
Definition: msg.c:189
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:226
Attribute validation policy.
Definition: attr.h:63