2 * Copyright (c) 2008, 2009, 2010, 2011, 2012 Nicira, Inc.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at:
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
22 #include <sys/types.h>
25 #include "netlink-protocol.h"
28 #include "unaligned.h"
31 VLOG_DEFINE_THIS_MODULE(netlink);
33 /* A single (bad) Netlink message can in theory dump out many, many log
34 * messages, so the burst size is set quite high here to avoid missing useful
35 * information. Also, at high logging levels we log *all* Netlink messages. */
36 static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(60, 600);
38 /* Returns the nlmsghdr at the head of 'msg'.
40 * 'msg' must be at least as large as a nlmsghdr. */
42 nl_msg_nlmsghdr(const struct ofpbuf *msg)
44 return ofpbuf_at_assert(msg, 0, NLMSG_HDRLEN);
47 /* Returns the genlmsghdr just past 'msg''s nlmsghdr.
49 * Returns a null pointer if 'msg' is not large enough to contain an nlmsghdr
50 * and a genlmsghdr. */
52 nl_msg_genlmsghdr(const struct ofpbuf *msg)
54 return ofpbuf_at(msg, NLMSG_HDRLEN, GENL_HDRLEN);
57 /* If 'buffer' is a NLMSG_ERROR message, stores 0 in '*errorp' if it is an ACK
58 * message, otherwise a positive errno value, and returns true. If 'buffer' is
59 * not an NLMSG_ERROR message, returns false.
61 * 'msg' must be at least as large as a nlmsghdr. */
63 nl_msg_nlmsgerr(const struct ofpbuf *msg, int *errorp)
65 if (nl_msg_nlmsghdr(msg)->nlmsg_type == NLMSG_ERROR) {
66 struct nlmsgerr *err = ofpbuf_at(msg, NLMSG_HDRLEN, sizeof *err);
69 VLOG_ERR_RL(&rl, "received invalid nlmsgerr (%zd bytes < %zd)",
70 msg->size, NLMSG_HDRLEN + sizeof *err);
71 } else if (err->error <= 0 && err->error > INT_MIN) {
83 /* Ensures that 'b' has room for at least 'size' bytes plus netlink padding at
84 * its tail end, reallocating and copying its data if necessary. */
86 nl_msg_reserve(struct ofpbuf *msg, size_t size)
88 ofpbuf_prealloc_tailroom(msg, NLMSG_ALIGN(size));
91 /* Puts a nlmsghdr at the beginning of 'msg', which must be initially empty.
92 * Uses the given 'type' and 'flags'. 'expected_payload' should be
93 * an estimate of the number of payload bytes to be supplied; if the size of
94 * the payload is unknown a value of 0 is acceptable.
96 * 'type' is ordinarily an enumerated value specific to the Netlink protocol
97 * (e.g. RTM_NEWLINK, for NETLINK_ROUTE protocol). For Generic Netlink, 'type'
98 * is the family number obtained via nl_lookup_genl_family().
100 * 'flags' is a bit-mask that indicates what kind of request is being made. It
101 * is often NLM_F_REQUEST indicating that a request is being made, commonly
102 * or'd with NLM_F_ACK to request an acknowledgement.
104 * Sets the new nlmsghdr's nlmsg_len, nlmsg_seq, and nlmsg_pid fields to 0 for
105 * now. Functions that send Netlink messages will fill these in just before
106 * sending the message.
108 * nl_msg_put_genlmsghdr() is more convenient for composing a Generic Netlink
111 nl_msg_put_nlmsghdr(struct ofpbuf *msg,
112 size_t expected_payload, uint32_t type, uint32_t flags)
114 struct nlmsghdr *nlmsghdr;
116 assert(msg->size == 0);
118 nl_msg_reserve(msg, NLMSG_HDRLEN + expected_payload);
119 nlmsghdr = nl_msg_put_uninit(msg, NLMSG_HDRLEN);
120 nlmsghdr->nlmsg_len = 0;
121 nlmsghdr->nlmsg_type = type;
122 nlmsghdr->nlmsg_flags = flags;
123 nlmsghdr->nlmsg_seq = 0;
124 nlmsghdr->nlmsg_pid = 0;
127 /* Puts a nlmsghdr and genlmsghdr at the beginning of 'msg', which must be
128 * initially empty. 'expected_payload' should be an estimate of the number of
129 * payload bytes to be supplied; if the size of the payload is unknown a value
130 * of 0 is acceptable.
132 * 'family' is the family number obtained via nl_lookup_genl_family().
134 * 'flags' is a bit-mask that indicates what kind of request is being made. It
135 * is often NLM_F_REQUEST indicating that a request is being made, commonly
136 * or'd with NLM_F_ACK to request an acknowledgement.
138 * 'cmd' is an enumerated value specific to the Generic Netlink family
139 * (e.g. CTRL_CMD_NEWFAMILY for the GENL_ID_CTRL family).
141 * 'version' is a version number specific to the family and command (often 1).
143 * Sets the new nlmsghdr's nlmsg_pid field to 0 for now. nl_sock_send() will
144 * fill it in just before sending the message.
146 * nl_msg_put_nlmsghdr() should be used to compose Netlink messages that are
147 * not Generic Netlink messages. */
149 nl_msg_put_genlmsghdr(struct ofpbuf *msg, size_t expected_payload,
150 int family, uint32_t flags, uint8_t cmd, uint8_t version)
152 struct genlmsghdr *genlmsghdr;
154 nl_msg_put_nlmsghdr(msg, GENL_HDRLEN + expected_payload, family, flags);
155 assert(msg->size == NLMSG_HDRLEN);
156 genlmsghdr = nl_msg_put_uninit(msg, GENL_HDRLEN);
157 genlmsghdr->cmd = cmd;
158 genlmsghdr->version = version;
159 genlmsghdr->reserved = 0;
162 /* Appends the 'size' bytes of data in 'p', plus Netlink padding if needed, to
163 * the tail end of 'msg'. Data in 'msg' is reallocated and copied if
166 nl_msg_put(struct ofpbuf *msg, const void *data, size_t size)
168 memcpy(nl_msg_put_uninit(msg, size), data, size);
171 /* Appends 'size' bytes of data, plus Netlink padding if needed, to the tail
172 * end of 'msg', reallocating and copying its data if necessary. Returns a
173 * pointer to the first byte of the new data, which is left uninitialized. */
175 nl_msg_put_uninit(struct ofpbuf *msg, size_t size)
177 size_t pad = NLMSG_ALIGN(size) - size;
178 char *p = ofpbuf_put_uninit(msg, size + pad);
180 memset(p + size, 0, pad);
185 /* Prepends the 'size' bytes of data in 'p', plus Netlink padding if needed, to
186 * the head end of 'msg'. Data in 'msg' is reallocated and copied if
189 nl_msg_push(struct ofpbuf *msg, const void *data, size_t size)
191 memcpy(nl_msg_push_uninit(msg, size), data, size);
194 /* Prepends 'size' bytes of data, plus Netlink padding if needed, to the head
195 * end of 'msg', reallocating and copying its data if necessary. Returns a
196 * pointer to the first byte of the new data, which is left uninitialized. */
198 nl_msg_push_uninit(struct ofpbuf *msg, size_t size)
200 size_t pad = NLMSG_ALIGN(size) - size;
201 char *p = ofpbuf_push_uninit(msg, size + pad);
203 memset(p + size, 0, pad);
208 /* Appends a Netlink attribute of the given 'type' and room for 'size' bytes of
209 * data as its payload, plus Netlink padding if needed, to the tail end of
210 * 'msg', reallocating and copying its data if necessary. Returns a pointer to
211 * the first byte of data in the attribute, which is left uninitialized. */
213 nl_msg_put_unspec_uninit(struct ofpbuf *msg, uint16_t type, size_t size)
215 size_t total_size = NLA_HDRLEN + size;
216 struct nlattr* nla = nl_msg_put_uninit(msg, total_size);
217 assert(NLA_ALIGN(total_size) <= UINT16_MAX);
218 nla->nla_len = total_size;
219 nla->nla_type = type;
223 /* Appends a Netlink attribute of the given 'type' and the 'size' bytes of
224 * 'data' as its payload, to the tail end of 'msg', reallocating and copying
225 * its data if necessary. Returns a pointer to the first byte of data in the
226 * attribute, which is left uninitialized. */
228 nl_msg_put_unspec(struct ofpbuf *msg, uint16_t type,
229 const void *data, size_t size)
231 memcpy(nl_msg_put_unspec_uninit(msg, type, size), data, size);
234 /* Appends a Netlink attribute of the given 'type' and no payload to 'msg'.
235 * (Some Netlink protocols use the presence or absence of an attribute as a
238 nl_msg_put_flag(struct ofpbuf *msg, uint16_t type)
240 nl_msg_put_unspec(msg, type, NULL, 0);
243 /* Appends a Netlink attribute of the given 'type' and the given 8-bit 'value'
246 nl_msg_put_u8(struct ofpbuf *msg, uint16_t type, uint8_t value)
248 nl_msg_put_unspec(msg, type, &value, sizeof value);
251 /* Appends a Netlink attribute of the given 'type' and the given 16-bit host
252 * byte order 'value' to 'msg'. */
254 nl_msg_put_u16(struct ofpbuf *msg, uint16_t type, uint16_t value)
256 nl_msg_put_unspec(msg, type, &value, sizeof value);
259 /* Appends a Netlink attribute of the given 'type' and the given 32-bit host
260 * byte order 'value' to 'msg'. */
262 nl_msg_put_u32(struct ofpbuf *msg, uint16_t type, uint32_t value)
264 nl_msg_put_unspec(msg, type, &value, sizeof value);
267 /* Appends a Netlink attribute of the given 'type' and the given 64-bit host
268 * byte order 'value' to 'msg'. */
270 nl_msg_put_u64(struct ofpbuf *msg, uint16_t type, uint64_t value)
272 nl_msg_put_unspec(msg, type, &value, sizeof value);
275 /* Appends a Netlink attribute of the given 'type' and the given 16-bit network
276 * byte order 'value' to 'msg'. */
278 nl_msg_put_be16(struct ofpbuf *msg, uint16_t type, ovs_be16 value)
280 nl_msg_put_unspec(msg, type, &value, sizeof value);
283 /* Appends a Netlink attribute of the given 'type' and the given 32-bit network
284 * byte order 'value' to 'msg'. */
286 nl_msg_put_be32(struct ofpbuf *msg, uint16_t type, ovs_be32 value)
288 nl_msg_put_unspec(msg, type, &value, sizeof value);
291 /* Appends a Netlink attribute of the given 'type' and the given 64-bit network
292 * byte order 'value' to 'msg'. */
294 nl_msg_put_be64(struct ofpbuf *msg, uint16_t type, ovs_be64 value)
296 nl_msg_put_unspec(msg, type, &value, sizeof value);
299 /* Appends a Netlink attribute of the given 'type' and the given
300 * null-terminated string 'value' to 'msg'. */
302 nl_msg_put_string(struct ofpbuf *msg, uint16_t type, const char *value)
304 nl_msg_put_unspec(msg, type, value, strlen(value) + 1);
307 /* Prepends a Netlink attribute of the given 'type' and room for 'size' bytes
308 * of data as its payload, plus Netlink padding if needed, to the head end of
309 * 'msg', reallocating and copying its data if necessary. Returns a pointer to
310 * the first byte of data in the attribute, which is left uninitialized. */
312 nl_msg_push_unspec_uninit(struct ofpbuf *msg, uint16_t type, size_t size)
314 size_t total_size = NLA_HDRLEN + size;
315 struct nlattr* nla = nl_msg_push_uninit(msg, total_size);
316 assert(NLA_ALIGN(total_size) <= UINT16_MAX);
317 nla->nla_len = total_size;
318 nla->nla_type = type;
322 /* Prepends a Netlink attribute of the given 'type' and the 'size' bytes of
323 * 'data' as its payload, to the head end of 'msg', reallocating and copying
324 * its data if necessary. Returns a pointer to the first byte of data in the
325 * attribute, which is left uninitialized. */
327 nl_msg_push_unspec(struct ofpbuf *msg, uint16_t type,
328 const void *data, size_t size)
330 memcpy(nl_msg_push_unspec_uninit(msg, type, size), data, size);
333 /* Prepends a Netlink attribute of the given 'type' and no payload to 'msg'.
334 * (Some Netlink protocols use the presence or absence of an attribute as a
337 nl_msg_push_flag(struct ofpbuf *msg, uint16_t type)
339 nl_msg_push_unspec(msg, type, NULL, 0);
342 /* Prepends a Netlink attribute of the given 'type' and the given 8-bit 'value'
345 nl_msg_push_u8(struct ofpbuf *msg, uint16_t type, uint8_t value)
347 nl_msg_push_unspec(msg, type, &value, sizeof value);
350 /* Prepends a Netlink attribute of the given 'type' and the given 16-bit host
351 * byte order 'value' to 'msg'. */
353 nl_msg_push_u16(struct ofpbuf *msg, uint16_t type, uint16_t value)
355 nl_msg_push_unspec(msg, type, &value, sizeof value);
358 /* Prepends a Netlink attribute of the given 'type' and the given 32-bit host
359 * byte order 'value' to 'msg'. */
361 nl_msg_push_u32(struct ofpbuf *msg, uint16_t type, uint32_t value)
363 nl_msg_push_unspec(msg, type, &value, sizeof value);
366 /* Prepends a Netlink attribute of the given 'type' and the given 64-bit host
367 * byte order 'value' to 'msg'. */
369 nl_msg_push_u64(struct ofpbuf *msg, uint16_t type, uint64_t value)
371 nl_msg_push_unspec(msg, type, &value, sizeof value);
374 /* Prepends a Netlink attribute of the given 'type' and the given 16-bit
375 * network byte order 'value' to 'msg'. */
377 nl_msg_push_be16(struct ofpbuf *msg, uint16_t type, ovs_be16 value)
379 nl_msg_push_unspec(msg, type, &value, sizeof value);
382 /* Prepends a Netlink attribute of the given 'type' and the given 32-bit
383 * network byte order 'value' to 'msg'. */
385 nl_msg_push_be32(struct ofpbuf *msg, uint16_t type, ovs_be32 value)
387 nl_msg_push_unspec(msg, type, &value, sizeof value);
390 /* Prepends a Netlink attribute of the given 'type' and the given 64-bit
391 * network byte order 'value' to 'msg'. */
393 nl_msg_push_be64(struct ofpbuf *msg, uint16_t type, ovs_be64 value)
395 nl_msg_push_unspec(msg, type, &value, sizeof value);
398 /* Prepends a Netlink attribute of the given 'type' and the given
399 * null-terminated string 'value' to 'msg'. */
401 nl_msg_push_string(struct ofpbuf *msg, uint16_t type, const char *value)
403 nl_msg_push_unspec(msg, type, value, strlen(value) + 1);
406 /* Adds the header for nested Netlink attributes to 'msg', with the specified
407 * 'type', and returns the header's offset within 'msg'. The caller should add
408 * the content for the nested Netlink attribute to 'msg' (e.g. using the other
409 * nl_msg_*() functions), and then pass the returned offset to
410 * nl_msg_end_nested() to finish up the nested attributes. */
412 nl_msg_start_nested(struct ofpbuf *msg, uint16_t type)
414 size_t offset = msg->size;
415 nl_msg_put_unspec(msg, type, NULL, 0);
419 /* Finalizes a nested Netlink attribute in 'msg'. 'offset' should be the value
420 * returned by nl_msg_start_nested(). */
422 nl_msg_end_nested(struct ofpbuf *msg, size_t offset)
424 struct nlattr *attr = ofpbuf_at_assert(msg, offset, sizeof *attr);
425 attr->nla_len = msg->size - offset;
428 /* Appends a nested Netlink attribute of the given 'type', with the 'size'
429 * bytes of content starting at 'data', to 'msg'. */
431 nl_msg_put_nested(struct ofpbuf *msg,
432 uint16_t type, const void *data, size_t size)
434 size_t offset = nl_msg_start_nested(msg, type);
435 nl_msg_put(msg, data, size);
436 nl_msg_end_nested(msg, offset);
439 /* If 'buffer' begins with a valid "struct nlmsghdr", pulls the header and its
440 * payload off 'buffer', stores header and payload in 'msg->data' and
441 * 'msg->size', and returns a pointer to the header.
443 * If 'buffer' does not begin with a "struct nlmsghdr" or begins with one that
444 * is invalid, returns NULL without modifying 'buffer'. */
446 nl_msg_next(struct ofpbuf *buffer, struct ofpbuf *msg)
448 if (buffer->size >= sizeof(struct nlmsghdr)) {
449 struct nlmsghdr *nlmsghdr = nl_msg_nlmsghdr(buffer);
450 size_t len = nlmsghdr->nlmsg_len;
451 if (len >= sizeof *nlmsghdr && len <= buffer->size) {
452 ofpbuf_use_const(msg, nlmsghdr, len);
453 ofpbuf_pull(buffer, len);
465 /* Returns the bits of 'nla->nla_type' that are significant for determining its
468 nl_attr_type(const struct nlattr *nla)
470 return nla->nla_type & NLA_TYPE_MASK;
473 /* Returns the first byte in the payload of attribute 'nla'. */
475 nl_attr_get(const struct nlattr *nla)
477 assert(nla->nla_len >= NLA_HDRLEN);
481 /* Returns the number of bytes in the payload of attribute 'nla'. */
483 nl_attr_get_size(const struct nlattr *nla)
485 assert(nla->nla_len >= NLA_HDRLEN);
486 return nla->nla_len - NLA_HDRLEN;
489 /* Asserts that 'nla''s payload is at least 'size' bytes long, and returns the
490 * first byte of the payload. */
492 nl_attr_get_unspec(const struct nlattr *nla, size_t size)
494 assert(nla->nla_len >= NLA_HDRLEN + size);
498 /* Returns true if 'nla' is nonnull. (Some Netlink protocols use the presence
499 * or absence of an attribute as a Boolean flag.) */
501 nl_attr_get_flag(const struct nlattr *nla)
506 #define NL_ATTR_GET_AS(NLA, TYPE) \
507 (*(TYPE*) nl_attr_get_unspec(nla, sizeof(TYPE)))
509 /* Returns the 8-bit value in 'nla''s payload.
511 * Asserts that 'nla''s payload is at least 1 byte long. */
513 nl_attr_get_u8(const struct nlattr *nla)
515 return NL_ATTR_GET_AS(nla, uint8_t);
518 /* Returns the 16-bit host byte order value in 'nla''s payload.
520 * Asserts that 'nla''s payload is at least 2 bytes long. */
522 nl_attr_get_u16(const struct nlattr *nla)
524 return NL_ATTR_GET_AS(nla, uint16_t);
527 /* Returns the 32-bit host byte order value in 'nla''s payload.
529 * Asserts that 'nla''s payload is at least 4 bytes long. */
531 nl_attr_get_u32(const struct nlattr *nla)
533 return NL_ATTR_GET_AS(nla, uint32_t);
536 /* Returns the 64-bit host byte order value in 'nla''s payload.
538 * Asserts that 'nla''s payload is at least 8 bytes long. */
540 nl_attr_get_u64(const struct nlattr *nla)
542 const ovs_32aligned_u64 *x = nl_attr_get_unspec(nla, sizeof *x);
543 return get_32aligned_u64(x);
546 /* Returns the 16-bit network byte order value in 'nla''s payload.
548 * Asserts that 'nla''s payload is at least 2 bytes long. */
550 nl_attr_get_be16(const struct nlattr *nla)
552 return NL_ATTR_GET_AS(nla, ovs_be16);
555 /* Returns the 32-bit network byte order value in 'nla''s payload.
557 * Asserts that 'nla''s payload is at least 4 bytes long. */
559 nl_attr_get_be32(const struct nlattr *nla)
561 return NL_ATTR_GET_AS(nla, ovs_be32);
564 /* Returns the 64-bit network byte order value in 'nla''s payload.
566 * Asserts that 'nla''s payload is at least 8 bytes long. */
568 nl_attr_get_be64(const struct nlattr *nla)
570 const ovs_32aligned_be64 *x = nl_attr_get_unspec(nla, sizeof *x);
571 return get_32aligned_be64(x);
574 /* Returns the null-terminated string value in 'nla''s payload.
576 * Asserts that 'nla''s payload contains a null-terminated string. */
578 nl_attr_get_string(const struct nlattr *nla)
580 assert(nla->nla_len > NLA_HDRLEN);
581 assert(memchr(nl_attr_get(nla), '\0', nla->nla_len - NLA_HDRLEN) != NULL);
582 return nl_attr_get(nla);
585 /* Initializes 'nested' to the payload of 'nla'. */
587 nl_attr_get_nested(const struct nlattr *nla, struct ofpbuf *nested)
589 ofpbuf_use_const(nested, nl_attr_get(nla), nl_attr_get_size(nla));
592 /* Default minimum and maximum payload sizes for each type of attribute. */
593 static const size_t attr_len_range[][2] = {
594 [0 ... N_NL_ATTR_TYPES - 1] = { 0, SIZE_MAX },
595 [NL_A_U8] = { 1, 1 },
596 [NL_A_U16] = { 2, 2 },
597 [NL_A_U32] = { 4, 4 },
598 [NL_A_U64] = { 8, 8 },
599 [NL_A_STRING] = { 1, SIZE_MAX },
600 [NL_A_FLAG] = { 0, SIZE_MAX },
601 [NL_A_NESTED] = { 0, SIZE_MAX },
605 nl_attr_validate(const struct nlattr *nla, const struct nl_policy *policy)
607 uint16_t type = nl_attr_type(nla);
612 if (policy->type == NL_A_NO_ATTR) {
616 /* Figure out min and max length. */
617 min_len = policy->min_len;
619 min_len = attr_len_range[policy->type][0];
621 max_len = policy->max_len;
623 max_len = attr_len_range[policy->type][1];
627 len = nl_attr_get_size(nla);
628 if (len < min_len || len > max_len) {
629 VLOG_DBG_RL(&rl, "attr %"PRIu16" length %zu not in "
630 "allowed range %zu...%zu", type, len, min_len, max_len);
634 /* Strings must be null terminated and must not have embedded nulls. */
635 if (policy->type == NL_A_STRING) {
636 if (((char *) nla)[nla->nla_len - 1]) {
637 VLOG_DBG_RL(&rl, "attr %"PRIu16" lacks null at end", type);
640 if (memchr(nla + 1, '\0', len - 1) != NULL) {
641 VLOG_DBG_RL(&rl, "attr %"PRIu16" has bad length", type);
649 /* Parses the 'msg' starting at the given 'nla_offset' as a sequence of Netlink
650 * attributes. 'policy[i]', for 0 <= i < n_attrs, specifies how the attribute
651 * with nla_type == i is parsed; a pointer to attribute i is stored in
652 * attrs[i]. Returns true if successful, false on failure.
654 * If the Netlink attributes in 'msg' follow a Netlink header and a Generic
655 * Netlink header, then 'nla_offset' should be NLMSG_HDRLEN + GENL_HDRLEN. */
657 nl_policy_parse(const struct ofpbuf *msg, size_t nla_offset,
658 const struct nl_policy policy[],
659 struct nlattr *attrs[], size_t n_attrs)
665 memset(attrs, 0, n_attrs * sizeof *attrs);
667 if (msg->size < nla_offset) {
668 VLOG_DBG_RL(&rl, "missing headers in nl_policy_parse");
672 NL_ATTR_FOR_EACH (nla, left,
673 (struct nlattr *) ((char *) msg->data + nla_offset),
674 msg->size - nla_offset)
676 uint16_t type = nl_attr_type(nla);
677 if (type < n_attrs && policy[type].type != NL_A_NO_ATTR) {
678 const struct nl_policy *e = &policy[type];
679 if (!nl_attr_validate(nla, e)) {
683 VLOG_DBG_RL(&rl, "duplicate attr %"PRIu16, type);
689 VLOG_DBG_RL(&rl, "attributes followed by garbage");
693 for (i = 0; i < n_attrs; i++) {
694 const struct nl_policy *e = &policy[i];
695 if (!e->optional && e->type != NL_A_NO_ATTR && !attrs[i]) {
696 VLOG_DBG_RL(&rl, "required attr %zu missing", i);
703 /* Parses the Netlink attributes within 'nla'. 'policy[i]', for 0 <= i <
704 * n_attrs, specifies how the attribute with nla_type == i is parsed; a pointer
705 * to attribute i is stored in attrs[i]. Returns true if successful, false on
708 nl_parse_nested(const struct nlattr *nla, const struct nl_policy policy[],
709 struct nlattr *attrs[], size_t n_attrs)
713 nl_attr_get_nested(nla, &buf);
714 return nl_policy_parse(&buf, 0, policy, attrs, n_attrs);
717 const struct nlattr *
718 nl_attr_find__(const struct nlattr *attrs, size_t size, uint16_t type)
720 const struct nlattr *nla;
723 NL_ATTR_FOR_EACH (nla, left, attrs, size) {
724 if (nl_attr_type(nla) == type) {
731 /* Returns the first Netlink attribute within 'buf' with the specified 'type',
732 * skipping a header of 'hdr_len' bytes at the beginning of 'buf'.
734 * This function does not validate the attribute's length. */
735 const struct nlattr *
736 nl_attr_find(const struct ofpbuf *buf, size_t hdr_len, uint16_t type)
738 const uint8_t *start = (const uint8_t *) buf->data + hdr_len;
739 return nl_attr_find__((const struct nlattr *) start, buf->size - hdr_len,
743 /* Returns the first Netlink attribute within 'nla' with the specified
746 * This function does not validate the attribute's length. */
747 const struct nlattr *
748 nl_attr_find_nested(const struct nlattr *nla, uint16_t type)
750 return nl_attr_find__(nl_attr_get(nla), nl_attr_get_size(nla), type);