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