lib/netlink.c

   1 /*
   2  * Copyright (c) 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015 Nicira, Inc.
   3  *
   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:
   7  *
   8  *     http://www.apache.org/licenses/LICENSE-2.0
   9  *
  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.
  15  */
  16
  17 #include <config.h>
  18 #include "netlink.h"
  19 #include <errno.h>
  20 #include <inttypes.h>
  21 #include <sys/types.h>
  22 #include <unistd.h>
  23 #include "coverage.h"
  24 #include "flow.h"
  25 #include "netlink-protocol.h"
  26 #include "openvswitch/ofpbuf.h"
  27 #include "timeval.h"
  28 #include "unaligned.h"
  29 #include "openvswitch/vlog.h"
  30 #include "util.h"
  31
  32 VLOG_DEFINE_THIS_MODULE(netlink);
  33
  34 /* A single (bad) Netlink message can in theory dump out many, many log
  35  * messages, so the burst size is set quite high here to avoid missing useful
  36  * information.  Also, at high logging levels we log *all* Netlink messages. */
  37 static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(60, 600);
  38
  39 /* Returns the nlmsghdr at the head of 'msg'.
  40  *
  41  * 'msg' must be at least as large as a nlmsghdr. */
  42 struct nlmsghdr *
  43 nl_msg_nlmsghdr(const struct ofpbuf *msg)
  44 {
  45     return ofpbuf_at_assert(msg, 0, NLMSG_HDRLEN);
  46 }
  47
  48 /* Returns the genlmsghdr just past 'msg''s nlmsghdr.
  49  *
  50  * Returns a null pointer if 'msg' is not large enough to contain an nlmsghdr
  51  * and a genlmsghdr. */
  52 struct genlmsghdr *
  53 nl_msg_genlmsghdr(const struct ofpbuf *msg)
  54 {
  55     return ofpbuf_at(msg, NLMSG_HDRLEN, GENL_HDRLEN);
  56 }
  57
  58 /* If 'buffer' is a NLMSG_ERROR message, stores 0 in '*errorp' if it is an ACK
  59  * message, otherwise a positive errno value, and returns true.  If 'buffer' is
  60  * not an NLMSG_ERROR message, returns false.
  61  *
  62  * 'msg' must be at least as large as a nlmsghdr. */
  63 bool
  64 nl_msg_nlmsgerr(const struct ofpbuf *msg, int *errorp)
  65 {
  66     if (nl_msg_nlmsghdr(msg)->nlmsg_type == NLMSG_ERROR) {
  67         struct nlmsgerr *err = ofpbuf_at(msg, NLMSG_HDRLEN, sizeof *err);
  68         int code = EPROTO;
  69         if (!err) {
  70             VLOG_ERR_RL(&rl, "received invalid nlmsgerr (%"PRIu32" bytes < %"PRIuSIZE")",
  71                         msg->size, NLMSG_HDRLEN + sizeof *err);
  72         } else if (err->error <= 0 && err->error > INT_MIN) {
  73             code = -err->error;
  74         }
  75         if (errorp) {
  76             *errorp = code;
  77         }
  78         return true;
  79     } else {
  80         return false;
  81     }
  82 }
  83
  84 /* Ensures that 'b' has room for at least 'size' bytes plus netlink padding at
  85  * its tail end, reallocating and copying its data if necessary. */
  86 void
  87 nl_msg_reserve(struct ofpbuf *msg, size_t size)
  88 {
  89     ofpbuf_prealloc_tailroom(msg, NLMSG_ALIGN(size));
  90 }
  91
  92 /* Puts a nlmsghdr at the beginning of 'msg', which must be initially empty.
  93  * Uses the given 'type' and 'flags'.  'expected_payload' should be
  94  * an estimate of the number of payload bytes to be supplied; if the size of
  95  * the payload is unknown a value of 0 is acceptable.
  96  *
  97  * 'type' is ordinarily an enumerated value specific to the Netlink protocol
  98  * (e.g. RTM_NEWLINK, for NETLINK_ROUTE protocol).  For Generic Netlink, 'type'
  99  * is the family number obtained via nl_lookup_genl_family().
 100  *
 101  * 'flags' is a bit-mask that indicates what kind of request is being made.  It
 102  * is often NLM_F_REQUEST indicating that a request is being made, commonly
 103  * or'd with NLM_F_ACK to request an acknowledgement.
 104  *
 105  * Sets the new nlmsghdr's nlmsg_len, nlmsg_seq, and nlmsg_pid fields to 0 for
 106  * now.  Functions that send Netlink messages will fill these in just before
 107  * sending the message.
 108  *
 109  * nl_msg_put_genlmsghdr() is more convenient for composing a Generic Netlink
 110  * message. */
 111 void
 112 nl_msg_put_nlmsghdr(struct ofpbuf *msg,
 113                     size_t expected_payload, uint32_t type, uint32_t flags)
 114 {
 115     struct nlmsghdr *nlmsghdr;
 116
 117     ovs_assert(msg->size == 0);
 118
 119     nl_msg_reserve(msg, NLMSG_HDRLEN + expected_payload);
 120     nlmsghdr = nl_msg_put_uninit(msg, NLMSG_HDRLEN);
 121     nlmsghdr->nlmsg_len = 0;
 122     nlmsghdr->nlmsg_type = type;
 123     nlmsghdr->nlmsg_flags = flags;
 124     nlmsghdr->nlmsg_seq = 0;
 125     nlmsghdr->nlmsg_pid = 0;
 126 }
 127
 128 /* Puts a nlmsghdr and genlmsghdr at the beginning of 'msg', which must be
 129  * initially empty.  'expected_payload' should be an estimate of the number of
 130  * payload bytes to be supplied; if the size of the payload is unknown a value
 131  * of 0 is acceptable.
 132  *
 133  * 'family' is the family number obtained via nl_lookup_genl_family().
 134  *
 135  * 'flags' is a bit-mask that indicates what kind of request is being made.  It
 136  * is often NLM_F_REQUEST indicating that a request is being made, commonly
 137  * or'd with NLM_F_ACK to request an acknowledgement.
 138  *
 139  * 'cmd' is an enumerated value specific to the Generic Netlink family
 140  * (e.g. CTRL_CMD_NEWFAMILY for the GENL_ID_CTRL family).
 141  *
 142  * 'version' is a version number specific to the family and command (often 1).
 143  *
 144  * Sets the new nlmsghdr's nlmsg_pid field to 0 for now.  nl_sock_send() will
 145  * fill it in just before sending the message.
 146  *
 147  * nl_msg_put_nlmsghdr() should be used to compose Netlink messages that are
 148  * not Generic Netlink messages. */
 149 void
 150 nl_msg_put_genlmsghdr(struct ofpbuf *msg, size_t expected_payload,
 151                       int family, uint32_t flags, uint8_t cmd, uint8_t version)
 152 {
 153     struct genlmsghdr *genlmsghdr;
 154
 155     nl_msg_put_nlmsghdr(msg, GENL_HDRLEN + expected_payload, family, flags);
 156     ovs_assert(msg->size == NLMSG_HDRLEN);
 157     genlmsghdr = nl_msg_put_uninit(msg, GENL_HDRLEN);
 158     genlmsghdr->cmd = cmd;
 159     genlmsghdr->version = version;
 160     genlmsghdr->reserved = 0;
 161 }
 162
 163 /* Appends the 'size' bytes of data in 'p', plus Netlink padding if needed, to
 164  * the tail end of 'msg'.  Data in 'msg' is reallocated and copied if
 165  * necessary. */
 166 void
 167 nl_msg_put(struct ofpbuf *msg, const void *data, size_t size)
 168 {
 169     memcpy(nl_msg_put_uninit(msg, size), data, size);
 170 }
 171
 172 /* Appends 'size' bytes of data, plus Netlink padding if needed, to the tail
 173  * end of 'msg', reallocating and copying its data if necessary.  Returns a
 174  * pointer to the first byte of the new data, which is left uninitialized. */
 175 void *
 176 nl_msg_put_uninit(struct ofpbuf *msg, size_t size)
 177 {
 178     size_t pad = PAD_SIZE(size, NLMSG_ALIGNTO);
 179     char *p = ofpbuf_put_uninit(msg, size + pad);
 180     if (pad) {
 181         memset(p + size, 0, pad);
 182     }
 183     return p;
 184 }
 185
 186 /* Prepends the 'size' bytes of data in 'p', plus Netlink padding if needed, to
 187  * the head end of 'msg'.  Data in 'msg' is reallocated and copied if
 188  * necessary. */
 189 void
 190 nl_msg_push(struct ofpbuf *msg, const void *data, size_t size)
 191 {
 192     memcpy(nl_msg_push_uninit(msg, size), data, size);
 193 }
 194
 195 /* Prepends 'size' bytes of data, plus Netlink padding if needed, to the head
 196  * end of 'msg', reallocating and copying its data if necessary.  Returns a
 197  * pointer to the first byte of the new data, which is left uninitialized. */
 198 void *
 199 nl_msg_push_uninit(struct ofpbuf *msg, size_t size)
 200 {
 201     size_t pad = PAD_SIZE(size, NLMSG_ALIGNTO);
 202     char *p = ofpbuf_push_uninit(msg, size + pad);
 203     if (pad) {
 204         memset(p + size, 0, pad);
 205     }
 206     return p;
 207 }
 208
 209 /* Appends a Netlink attribute of the given 'type' and room for 'size' bytes of
 210  * data as its payload, plus Netlink padding if needed, to the tail end of
 211  * 'msg', reallocating and copying its data if necessary.  Returns a pointer to
 212  * the first byte of data in the attribute, which is left uninitialized. */
 213 void *
 214 nl_msg_put_unspec_uninit(struct ofpbuf *msg, uint16_t type, size_t size)
 215 {
 216     size_t total_size = NLA_HDRLEN + size;
 217     struct nlattr* nla = nl_msg_put_uninit(msg, total_size);
 218     ovs_assert(!nl_attr_oversized(size));
 219     nla->nla_len = total_size;
 220     nla->nla_type = type;
 221     return nla + 1;
 222 }
 223
 224 /* Appends a Netlink attribute of the given 'type' and room for 'size' bytes of
 225  * data as its payload, plus Netlink padding if needed, to the tail end of
 226  * 'msg', reallocating and copying its data if necessary.  Returns a pointer to
 227  * the first byte of data in the attribute, which is zeroed. */
 228 void *
 229 nl_msg_put_unspec_zero(struct ofpbuf *msg, uint16_t type, size_t size)
 230 {
 231     void *data = nl_msg_put_unspec_uninit(msg, type, size);
 232     memset(data, 0, size);
 233     return data;
 234 }
 235
 236 /* Appends a Netlink attribute of the given 'type' and the 'size' bytes of
 237  * 'data' as its payload, to the tail end of 'msg', reallocating and copying
 238  * its data if necessary.  Returns a pointer to the first byte of data in the
 239  * attribute, which is left uninitialized. */
 240 void
 241 nl_msg_put_unspec(struct ofpbuf *msg, uint16_t type,
 242                   const void *data, size_t size)
 243 {
 244     void *ptr;
 245
 246     ptr = nl_msg_put_unspec_uninit(msg, type, size);
 247     nullable_memcpy(ptr, data, size);
 248 }
 249
 250 /* Appends a Netlink attribute of the given 'type' and no payload to 'msg'.
 251  * (Some Netlink protocols use the presence or absence of an attribute as a
 252  * Boolean flag.) */
 253 void
 254 nl_msg_put_flag(struct ofpbuf *msg, uint16_t type)
 255 {
 256     nl_msg_put_unspec(msg, type, NULL, 0);
 257 }
 258
 259 /* Appends a Netlink attribute of the given 'type' and the given 8-bit 'value'
 260  * to 'msg'. */
 261 void
 262 nl_msg_put_u8(struct ofpbuf *msg, uint16_t type, uint8_t value)
 263 {
 264     nl_msg_put_unspec(msg, type, &value, sizeof value);
 265 }
 266
 267 /* Appends a Netlink attribute of the given 'type' and the given 16-bit host
 268  * byte order 'value' to 'msg'. */
 269 void
 270 nl_msg_put_u16(struct ofpbuf *msg, uint16_t type, uint16_t value)
 271 {
 272     nl_msg_put_unspec(msg, type, &value, sizeof value);
 273 }
 274
 275 /* Appends a Netlink attribute of the given 'type' and the given 32-bit host
 276  * byte order 'value' to 'msg'. */
 277 void
 278 nl_msg_put_u32(struct ofpbuf *msg, uint16_t type, uint32_t value)
 279 {
 280     nl_msg_put_unspec(msg, type, &value, sizeof value);
 281 }
 282
 283 /* Appends a Netlink attribute of the given 'type' and the given 64-bit host
 284  * byte order 'value' to 'msg'. */
 285 void
 286 nl_msg_put_u64(struct ofpbuf *msg, uint16_t type, uint64_t value)
 287 {
 288     nl_msg_put_unspec(msg, type, &value, sizeof value);
 289 }
 290
 291 /* Appends a Netlink attribute of the given 'type' and the given 16-bit network
 292  * byte order 'value' to 'msg'. */
 293 void
 294 nl_msg_put_be16(struct ofpbuf *msg, uint16_t type, ovs_be16 value)
 295 {
 296     nl_msg_put_unspec(msg, type, &value, sizeof value);
 297 }
 298
 299 /* Appends a Netlink attribute of the given 'type' and the given 32-bit network
 300  * byte order 'value' to 'msg'. */
 301 void
 302 nl_msg_put_be32(struct ofpbuf *msg, uint16_t type, ovs_be32 value)
 303 {
 304     nl_msg_put_unspec(msg, type, &value, sizeof value);
 305 }
 306
 307 /* Appends a Netlink attribute of the given 'type' and the given 64-bit network
 308  * byte order 'value' to 'msg'. */
 309 void
 310 nl_msg_put_be64(struct ofpbuf *msg, uint16_t type, ovs_be64 value)
 311 {
 312     nl_msg_put_unspec(msg, type, &value, sizeof value);
 313 }
 314
 315 /* Appends a Netlink attribute of the given 'type' and the given IPv6
 316  * address order 'value' to 'msg'. */
 317 void
 318 nl_msg_put_in6_addr(struct ofpbuf *msg, uint16_t type,
 319                     const struct in6_addr *value)
 320 {
 321     nl_msg_put_unspec(msg, type, value, sizeof *value);
 322 }
 323
 324 /* Appends a Netlink attribute of the given 'type' and the given odp_port_t
 325  * 'value' to 'msg'. */
 326 void
 327 nl_msg_put_odp_port(struct ofpbuf *msg, uint16_t type, odp_port_t value)
 328 {
 329     nl_msg_put_u32(msg, type, odp_to_u32(value));
 330 }
 331
 332 /* Appends a Netlink attribute of the given 'type' with the 'len' characters
 333  * of 'value', followed by the null byte to 'msg'. */
 334 void
 335 nl_msg_put_string__(struct ofpbuf *msg, uint16_t type, const char *value,
 336                     size_t len)
 337 {
 338     char *data = nl_msg_put_unspec_uninit(msg, type, len + 1);
 339
 340     memcpy(data, value, len);
 341     data[len] = '\0';
 342 }
 343
 344 /* Appends a Netlink attribute of the given 'type' and the given
 345  * null-terminated string 'value' to 'msg'. */
 346 void
 347 nl_msg_put_string(struct ofpbuf *msg, uint16_t type, const char *value)
 348 {
 349     nl_msg_put_unspec(msg, type, value, strlen(value) + 1);
 350 }
 351
 352 /* Prepends a Netlink attribute of the given 'type' and room for 'size' bytes
 353  * of data as its payload, plus Netlink padding if needed, to the head end of
 354  * 'msg', reallocating and copying its data if necessary.  Returns a pointer to
 355  * the first byte of data in the attribute, which is left uninitialized. */
 356 void *
 357 nl_msg_push_unspec_uninit(struct ofpbuf *msg, uint16_t type, size_t size)
 358 {
 359     size_t total_size = NLA_HDRLEN + size;
 360     struct nlattr* nla = nl_msg_push_uninit(msg, total_size);
 361     ovs_assert(!nl_attr_oversized(size));
 362     nla->nla_len = total_size;
 363     nla->nla_type = type;
 364     return nla + 1;
 365 }
 366
 367 /* Prepends a Netlink attribute of the given 'type' and the 'size' bytes of
 368  * 'data' as its payload, to the head end of 'msg', reallocating and copying
 369  * its data if necessary.  Returns a pointer to the first byte of data in the
 370  * attribute, which is left uninitialized. */
 371 void
 372 nl_msg_push_unspec(struct ofpbuf *msg, uint16_t type,
 373                   const void *data, size_t size)
 374 {
 375     memcpy(nl_msg_push_unspec_uninit(msg, type, size), data, size);
 376 }
 377
 378 /* Prepends a Netlink attribute of the given 'type' and no payload to 'msg'.
 379  * (Some Netlink protocols use the presence or absence of an attribute as a
 380  * Boolean flag.) */
 381 void
 382 nl_msg_push_flag(struct ofpbuf *msg, uint16_t type)
 383 {
 384     nl_msg_push_unspec_uninit(msg, type, 0);
 385 }
 386
 387 /* Prepends a Netlink attribute of the given 'type' and the given 8-bit 'value'
 388  * to 'msg'. */
 389 void
 390 nl_msg_push_u8(struct ofpbuf *msg, uint16_t type, uint8_t value)
 391 {
 392     nl_msg_push_unspec(msg, type, &value, sizeof value);
 393 }
 394
 395 /* Prepends a Netlink attribute of the given 'type' and the given 16-bit host
 396  * byte order 'value' to 'msg'. */
 397 void
 398 nl_msg_push_u16(struct ofpbuf *msg, uint16_t type, uint16_t value)
 399 {
 400     nl_msg_push_unspec(msg, type, &value, sizeof value);
 401 }
 402
 403 /* Prepends a Netlink attribute of the given 'type' and the given 32-bit host
 404  * byte order 'value' to 'msg'. */
 405 void
 406 nl_msg_push_u32(struct ofpbuf *msg, uint16_t type, uint32_t value)
 407 {
 408     nl_msg_push_unspec(msg, type, &value, sizeof value);
 409 }
 410
 411 /* Prepends a Netlink attribute of the given 'type' and the given 64-bit host
 412  * byte order 'value' to 'msg'. */
 413 void
 414 nl_msg_push_u64(struct ofpbuf *msg, uint16_t type, uint64_t value)
 415 {
 416     nl_msg_push_unspec(msg, type, &value, sizeof value);
 417 }
 418
 419 /* Prepends a Netlink attribute of the given 'type' and the given 16-bit
 420  * network byte order 'value' to 'msg'. */
 421 void
 422 nl_msg_push_be16(struct ofpbuf *msg, uint16_t type, ovs_be16 value)
 423 {
 424     nl_msg_push_unspec(msg, type, &value, sizeof value);
 425 }
 426
 427 /* Prepends a Netlink attribute of the given 'type' and the given 32-bit
 428  * network byte order 'value' to 'msg'. */
 429 void
 430 nl_msg_push_be32(struct ofpbuf *msg, uint16_t type, ovs_be32 value)
 431 {
 432     nl_msg_push_unspec(msg, type, &value, sizeof value);
 433 }
 434
 435 /* Prepends a Netlink attribute of the given 'type' and the given 64-bit
 436  * network byte order 'value' to 'msg'. */
 437 void
 438 nl_msg_push_be64(struct ofpbuf *msg, uint16_t type, ovs_be64 value)
 439 {
 440     nl_msg_push_unspec(msg, type, &value, sizeof value);
 441 }
 442
 443 /* Prepends a Netlink attribute of the given 'type' and the given
 444  * null-terminated string 'value' to 'msg'. */
 445 void
 446 nl_msg_push_string(struct ofpbuf *msg, uint16_t type, const char *value)
 447 {
 448     nl_msg_push_unspec(msg, type, value, strlen(value) + 1);
 449 }
 450
 451 /* Adds the header for nested Netlink attributes to 'msg', with the specified
 452  * 'type', and returns the header's offset within 'msg'.  The caller should add
 453  * the content for the nested Netlink attribute to 'msg' (e.g. using the other
 454  * nl_msg_*() functions), and then pass the returned offset to
 455  * nl_msg_end_nested() to finish up the nested attributes. */
 456 size_t
 457 nl_msg_start_nested(struct ofpbuf *msg, uint16_t type)
 458 {
 459     size_t offset = msg->size;
 460     nl_msg_put_unspec_uninit(msg, type, 0);
 461     return offset;
 462 }
 463
 464 /* Finalizes a nested Netlink attribute in 'msg'.  'offset' should be the value
 465  * returned by nl_msg_start_nested(). */
 466 void
 467 nl_msg_end_nested(struct ofpbuf *msg, size_t offset)
 468 {
 469     struct nlattr *attr = ofpbuf_at_assert(msg, offset, sizeof *attr);
 470     attr->nla_len = msg->size - offset;
 471 }
 472
 473 /* Cancel a nested Netlink attribute in 'msg'.  'offset' should be the value
 474  * returned by nl_msg_start_nested(). */
 475 void
 476 nl_msg_cancel_nested(struct ofpbuf *msg, size_t offset)
 477 {
 478     msg->size = offset;
 479 }
 480
 481 /* Same as nls_msg_end_nested() when the nested Netlink contains non empty
 482  * message. Otherwise, drop the nested message header from 'msg'.
 483  *
 484  * Return true if the nested message has been dropped.  */
 485 bool
 486 nl_msg_end_non_empty_nested(struct ofpbuf *msg, size_t offset)
 487 {
 488     nl_msg_end_nested(msg, offset);
 489
 490     struct nlattr *attr = ofpbuf_at_assert(msg, offset, sizeof *attr);
 491     if (!nl_attr_get_size(attr)) {
 492         nl_msg_cancel_nested(msg, offset);
 493         return true;
 494     } else {
 495         return false;
 496     }
 497 }
 498
 499 /* Appends a nested Netlink attribute of the given 'type', with the 'size'
 500  * bytes of content starting at 'data', to 'msg'. */
 501 void
 502 nl_msg_put_nested(struct ofpbuf *msg,
 503                   uint16_t type, const void *data, size_t size)
 504 {
 505     size_t offset = nl_msg_start_nested(msg, type);
 506     nl_msg_put(msg, data, size);
 507     nl_msg_end_nested(msg, offset);
 508 }
 509
 510 /* If 'buffer' begins with a valid "struct nlmsghdr", pulls the header and its
 511  * payload off 'buffer', stores header and payload in 'msg->data' and
 512  * 'msg->size', and returns a pointer to the header.
 513  *
 514  * If 'buffer' does not begin with a "struct nlmsghdr" or begins with one that
 515  * is invalid, returns NULL and clears 'buffer' and 'msg'. */
 516 struct nlmsghdr *
 517 nl_msg_next(struct ofpbuf *buffer, struct ofpbuf *msg)
 518 {
 519     if (buffer->size >= sizeof(struct nlmsghdr)) {
 520         struct nlmsghdr *nlmsghdr = nl_msg_nlmsghdr(buffer);
 521         size_t len = nlmsghdr->nlmsg_len;
 522         if (len >= sizeof *nlmsghdr && len <= buffer->size) {
 523             ofpbuf_use_const(msg, nlmsghdr, len);
 524             ofpbuf_pull(buffer, len);
 525             return nlmsghdr;
 526         }
 527     }
 528
 529     ofpbuf_clear(buffer);
 530     msg->data = NULL;
 531     msg->size = 0;
 532     return NULL;
 533 }
 534
 535 /* Returns true if a Netlink attribute with a payload that is 'payload_size'
 536  * bytes long would be oversized, that is, if it's not possible to create an
 537  * nlattr of that size because its size wouldn't fit in the 16-bit nla_len
 538  * field. */
 539 bool
 540 nl_attr_oversized(size_t payload_size)
 541 {
 542     return payload_size > UINT16_MAX - NLA_HDRLEN;
 543 }
 544 \f
 545 /* Attributes. */
 546
 547 /* Returns the bits of 'nla->nla_type' that are significant for determining its
 548  * type. */
 549 int
 550 nl_attr_type(const struct nlattr *nla)
 551 {
 552     return nla->nla_type & NLA_TYPE_MASK;
 553 }
 554
 555 /* Returns the first byte in the payload of attribute 'nla'. */
 556 const void *
 557 nl_attr_get(const struct nlattr *nla)
 558 {
 559     ovs_assert(nla->nla_len >= NLA_HDRLEN);
 560     return nla + 1;
 561 }
 562
 563 /* Returns the number of bytes in the payload of attribute 'nla'. */
 564 size_t
 565 nl_attr_get_size(const struct nlattr *nla)
 566 {
 567     ovs_assert(nla->nla_len >= NLA_HDRLEN);
 568     return nla->nla_len - NLA_HDRLEN;
 569 }
 570
 571 /* Asserts that 'nla''s payload is at least 'size' bytes long, and returns the
 572  * first byte of the payload. */
 573 const void *
 574 nl_attr_get_unspec(const struct nlattr *nla, size_t size)
 575 {
 576     ovs_assert(nla->nla_len >= NLA_HDRLEN + size);
 577     return nla + 1;
 578 }
 579
 580 /* Returns true if 'nla' is nonnull.  (Some Netlink protocols use the presence
 581  * or absence of an attribute as a Boolean flag.) */
 582 bool
 583 nl_attr_get_flag(const struct nlattr *nla)
 584 {
 585     return nla != NULL;
 586 }
 587
 588 #define NL_ATTR_GET_AS(NLA, TYPE) \
 589         (*(TYPE*) nl_attr_get_unspec(nla, sizeof(TYPE)))
 590
 591 /* Returns the 8-bit value in 'nla''s payload.
 592  *
 593  * Asserts that 'nla''s payload is at least 1 byte long. */
 594 uint8_t
 595 nl_attr_get_u8(const struct nlattr *nla)
 596 {
 597     return NL_ATTR_GET_AS(nla, uint8_t);
 598 }
 599
 600 /* Returns the 16-bit host byte order value in 'nla''s payload.
 601  *
 602  * Asserts that 'nla''s payload is at least 2 bytes long. */
 603 uint16_t
 604 nl_attr_get_u16(const struct nlattr *nla)
 605 {
 606     return NL_ATTR_GET_AS(nla, uint16_t);
 607 }
 608
 609 /* Returns the 32-bit host byte order value in 'nla''s payload.
 610  *
 611  * Asserts that 'nla''s payload is at least 4 bytes long. */
 612 uint32_t
 613 nl_attr_get_u32(const struct nlattr *nla)
 614 {
 615     return NL_ATTR_GET_AS(nla, uint32_t);
 616 }
 617
 618 /* Returns the 64-bit host byte order value in 'nla''s payload.
 619  *
 620  * Asserts that 'nla''s payload is at least 8 bytes long. */
 621 uint64_t
 622 nl_attr_get_u64(const struct nlattr *nla)
 623 {
 624     const ovs_32aligned_u64 *x = nl_attr_get_unspec(nla, sizeof *x);
 625     return get_32aligned_u64(x);
 626 }
 627
 628 /* Returns the 16-bit network byte order value in 'nla''s payload.
 629  *
 630  * Asserts that 'nla''s payload is at least 2 bytes long. */
 631 ovs_be16
 632 nl_attr_get_be16(const struct nlattr *nla)
 633 {
 634     return NL_ATTR_GET_AS(nla, ovs_be16);
 635 }
 636
 637 /* Returns the 32-bit network byte order value in 'nla''s payload.
 638  *
 639  * Asserts that 'nla''s payload is at least 4 bytes long. */
 640 ovs_be32
 641 nl_attr_get_be32(const struct nlattr *nla)
 642 {
 643     return NL_ATTR_GET_AS(nla, ovs_be32);
 644 }
 645
 646 /* Returns the 64-bit network byte order value in 'nla''s payload.
 647  *
 648  * Asserts that 'nla''s payload is at least 8 bytes long. */
 649 ovs_be64
 650 nl_attr_get_be64(const struct nlattr *nla)
 651 {
 652     const ovs_32aligned_be64 *x = nl_attr_get_unspec(nla, sizeof *x);
 653     return get_32aligned_be64(x);
 654 }
 655
 656 /* Returns the IPv6 address value in 'nla''s payload.
 657  *
 658  * Asserts that 'nla''s payload is at least 16 bytes long. */
 659 struct in6_addr
 660 nl_attr_get_in6_addr(const struct nlattr *nla)
 661 {
 662     return NL_ATTR_GET_AS(nla, struct in6_addr);
 663 }
 664
 665 /* Returns the 32-bit odp_port_t value in 'nla''s payload.
 666  *
 667  * Asserts that 'nla''s payload is at least 4 bytes long. */
 668 odp_port_t
 669 nl_attr_get_odp_port(const struct nlattr *nla)
 670 {
 671     return u32_to_odp(nl_attr_get_u32(nla));
 672 }
 673
 674 /* Returns the null-terminated string value in 'nla''s payload.
 675  *
 676  * Asserts that 'nla''s payload contains a null-terminated string. */
 677 const char *
 678 nl_attr_get_string(const struct nlattr *nla)
 679 {
 680     ovs_assert(nla->nla_len > NLA_HDRLEN);
 681     ovs_assert(memchr(nl_attr_get(nla), '\0', nla->nla_len - NLA_HDRLEN));
 682     return nl_attr_get(nla);
 683 }
 684
 685 /* Initializes 'nested' to the payload of 'nla'. */
 686 void
 687 nl_attr_get_nested(const struct nlattr *nla, struct ofpbuf *nested)
 688 {
 689     ofpbuf_use_const(nested, nl_attr_get(nla), nl_attr_get_size(nla));
 690 }
 691
 692 /* Default minimum payload size for each type of attribute. */
 693 static size_t
 694 min_attr_len(enum nl_attr_type type)
 695 {
 696     switch (type) {
 697     case NL_A_NO_ATTR: return 0;
 698     case NL_A_UNSPEC: return 0;
 699     case NL_A_U8: return 1;
 700     case NL_A_U16: return 2;
 701     case NL_A_U32: return 4;
 702     case NL_A_U64: return 8;
 703     case NL_A_STRING: return 1;
 704     case NL_A_FLAG: return 0;
 705     case NL_A_IPV6: return 16;
 706     case NL_A_NESTED: return 0;
 707     case N_NL_ATTR_TYPES: default: OVS_NOT_REACHED();
 708     }
 709 }
 710
 711 /* Default maximum payload size for each type of attribute. */
 712 static size_t
 713 max_attr_len(enum nl_attr_type type)
 714 {
 715     switch (type) {
 716     case NL_A_NO_ATTR: return SIZE_MAX;
 717     case NL_A_UNSPEC: return SIZE_MAX;
 718     case NL_A_U8: return 1;
 719     case NL_A_U16: return 2;
 720     case NL_A_U32: return 4;
 721     case NL_A_U64: return 8;
 722     case NL_A_STRING: return SIZE_MAX;
 723     case NL_A_FLAG: return SIZE_MAX;
 724     case NL_A_IPV6: return 16;
 725     case NL_A_NESTED: return SIZE_MAX;
 726     case N_NL_ATTR_TYPES: default: OVS_NOT_REACHED();
 727     }
 728 }
 729
 730 bool
 731 nl_attr_validate(const struct nlattr *nla, const struct nl_policy *policy)
 732 {
 733     uint16_t type = nl_attr_type(nla);
 734     size_t min_len;
 735     size_t max_len;
 736     size_t len;
 737
 738     if (policy->type == NL_A_NO_ATTR) {
 739         return true;
 740     }
 741
 742     /* Figure out min and max length. */
 743     min_len = policy->min_len;
 744     if (!min_len) {
 745         min_len = min_attr_len(policy->type);
 746     }
 747     max_len = policy->max_len;
 748     if (!max_len) {
 749         max_len = max_attr_len(policy->type);
 750     }
 751
 752     /* Verify length. */
 753     len = nl_attr_get_size(nla);
 754     if (len < min_len || len > max_len) {
 755         VLOG_DBG_RL(&rl, "attr %"PRIu16" length %"PRIuSIZE" not in "
 756                     "allowed range %"PRIuSIZE"...%"PRIuSIZE, type, len, min_len, max_len);
 757         return false;
 758     }
 759
 760     /* Strings must be null terminated and must not have embedded nulls. */
 761     if (policy->type == NL_A_STRING) {
 762         if (((char *) nla)[nla->nla_len - 1]) {
 763             VLOG_DBG_RL(&rl, "attr %"PRIu16" lacks null at end", type);
 764             return false;
 765         }
 766         if (memchr(nla + 1, '\0', len - 1) != NULL) {
 767             VLOG_DBG_RL(&rl, "attr %"PRIu16" has bad length", type);
 768             return false;
 769         }
 770     }
 771
 772     return true;
 773 }
 774
 775 /* Parses the 'msg' starting at the given 'nla_offset' as a sequence of Netlink
 776  * attributes.  'policy[i]', for 0 <= i < n_attrs, specifies how the attribute
 777  * with nla_type == i is parsed; a pointer to attribute i is stored in
 778  * attrs[i].  Returns true if successful, false on failure.
 779  *
 780  * If the Netlink attributes in 'msg' follow a Netlink header and a Generic
 781  * Netlink header, then 'nla_offset' should be NLMSG_HDRLEN + GENL_HDRLEN. */
 782 bool
 783 nl_policy_parse(const struct ofpbuf *msg, size_t nla_offset,
 784                 const struct nl_policy policy[],
 785                 struct nlattr *attrs[], size_t n_attrs)
 786 {
 787     struct nlattr *nla;
 788     size_t left;
 789     size_t i;
 790
 791     memset(attrs, 0, n_attrs * sizeof *attrs);
 792
 793     if (msg->size < nla_offset) {
 794         VLOG_DBG_RL(&rl, "missing headers in nl_policy_parse");
 795         return false;
 796     }
 797
 798     NL_ATTR_FOR_EACH (nla, left, ofpbuf_at(msg, nla_offset, 0),
 799                       msg->size - nla_offset)
 800     {
 801         uint16_t type = nl_attr_type(nla);
 802         if (type < n_attrs && policy[type].type != NL_A_NO_ATTR) {
 803             const struct nl_policy *e = &policy[type];
 804             if (!nl_attr_validate(nla, e)) {
 805                 return false;
 806             }
 807             if (attrs[type]) {
 808                 VLOG_DBG_RL(&rl, "duplicate attr %"PRIu16, type);
 809             }
 810             attrs[type] = nla;
 811         }
 812     }
 813     if (left) {
 814         VLOG_DBG_RL(&rl, "attributes followed by garbage");
 815         return false;
 816     }
 817
 818     for (i = 0; i < n_attrs; i++) {
 819         const struct nl_policy *e = &policy[i];
 820         if (!e->optional && e->type != NL_A_NO_ATTR && !attrs[i]) {
 821             VLOG_DBG_RL(&rl, "required attr %"PRIuSIZE" missing", i);
 822             return false;
 823         }
 824     }
 825     return true;
 826 }
 827
 828 /* Parses the Netlink attributes within 'nla'.  'policy[i]', for 0 <= i <
 829  * n_attrs, specifies how the attribute with nla_type == i is parsed; a pointer
 830  * to attribute i is stored in attrs[i].  Returns true if successful, false on
 831  * failure. */
 832 bool
 833 nl_parse_nested(const struct nlattr *nla, const struct nl_policy policy[],
 834                 struct nlattr *attrs[], size_t n_attrs)
 835 {
 836     struct ofpbuf buf;
 837
 838     nl_attr_get_nested(nla, &buf);
 839     return nl_policy_parse(&buf, 0, policy, attrs, n_attrs);
 840 }
 841
 842 const struct nlattr *
 843 nl_attr_find__(const struct nlattr *attrs, size_t size, uint16_t type)
 844 {
 845     const struct nlattr *nla;
 846     size_t left;
 847
 848     NL_ATTR_FOR_EACH (nla, left, attrs, size) {
 849         if (nl_attr_type(nla) == type) {
 850             return nla;
 851         }
 852     }
 853     return NULL;
 854 }
 855
 856 /* Returns the first Netlink attribute within 'buf' with the specified 'type',
 857  * skipping a header of 'hdr_len' bytes at the beginning of 'buf'.
 858  *
 859  * This function does not validate the attribute's length. */
 860 const struct nlattr *
 861 nl_attr_find(const struct ofpbuf *buf, size_t hdr_len, uint16_t type)
 862 {
 863     return nl_attr_find__(ofpbuf_at(buf, hdr_len, 0), buf->size - hdr_len,
 864                           type);
 865 }
 866
 867 /* Returns the first Netlink attribute within 'nla' with the specified
 868  * 'type'.
 869  *
 870  * This function does not validate the attribute's length. */
 871 const struct nlattr *
 872 nl_attr_find_nested(const struct nlattr *nla, uint16_t type)
 873 {
 874     return nl_attr_find__(nl_attr_get(nla), nl_attr_get_size(nla), type);
 875 }