lib/netlink.c

   1 /*
   2  * Copyright (c) 2008, 2009, 2010, 2011, 2012 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 <assert.h>
  20 #include <errno.h>
  21 #include <inttypes.h>
  22 #include <sys/types.h>
  23 #include <unistd.h>
  24 #include "coverage.h"
  25 #include "netlink-protocol.h"
  26 #include "ofpbuf.h"
  27 #include "timeval.h"
  28 #include "unaligned.h"
  29 #include "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 (%zd bytes < %zd)",
  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     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     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 = NLMSG_ALIGN(size) - size;
 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 = NLMSG_ALIGN(size) - size;
 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     assert(NLA_ALIGN(total_size) <= UINT16_MAX);
 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 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. */
 227 void
 228 nl_msg_put_unspec(struct ofpbuf *msg, uint16_t type,
 229                   const void *data, size_t size)
 230 {
 231     memcpy(nl_msg_put_unspec_uninit(msg, type, size), data, size);
 232 }
 233
 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
 236  * Boolean flag.) */
 237 void
 238 nl_msg_put_flag(struct ofpbuf *msg, uint16_t type)
 239 {
 240     nl_msg_put_unspec(msg, type, NULL, 0);
 241 }
 242
 243 /* Appends a Netlink attribute of the given 'type' and the given 8-bit 'value'
 244  * to 'msg'. */
 245 void
 246 nl_msg_put_u8(struct ofpbuf *msg, uint16_t type, uint8_t value)
 247 {
 248     nl_msg_put_unspec(msg, type, &value, sizeof value);
 249 }
 250
 251 /* Appends a Netlink attribute of the given 'type' and the given 16-bit host
 252  * byte order 'value' to 'msg'. */
 253 void
 254 nl_msg_put_u16(struct ofpbuf *msg, uint16_t type, uint16_t value)
 255 {
 256     nl_msg_put_unspec(msg, type, &value, sizeof value);
 257 }
 258
 259 /* Appends a Netlink attribute of the given 'type' and the given 32-bit host
 260  * byte order 'value' to 'msg'. */
 261 void
 262 nl_msg_put_u32(struct ofpbuf *msg, uint16_t type, uint32_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 64-bit host
 268  * byte order 'value' to 'msg'. */
 269 void
 270 nl_msg_put_u64(struct ofpbuf *msg, uint16_t type, uint64_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 16-bit network
 276  * byte order 'value' to 'msg'. */
 277 void
 278 nl_msg_put_be16(struct ofpbuf *msg, uint16_t type, ovs_be16 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 32-bit network
 284  * byte order 'value' to 'msg'. */
 285 void
 286 nl_msg_put_be32(struct ofpbuf *msg, uint16_t type, ovs_be32 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 64-bit network
 292  * byte order 'value' to 'msg'. */
 293 void
 294 nl_msg_put_be64(struct ofpbuf *msg, uint16_t type, ovs_be64 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
 300  * null-terminated string 'value' to 'msg'. */
 301 void
 302 nl_msg_put_string(struct ofpbuf *msg, uint16_t type, const char *value)
 303 {
 304     nl_msg_put_unspec(msg, type, value, strlen(value) + 1);
 305 }
 306
 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. */
 311 void *
 312 nl_msg_push_unspec_uninit(struct ofpbuf *msg, uint16_t type, size_t size)
 313 {
 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;
 319     return nla + 1;
 320 }
 321
 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. */
 326 void
 327 nl_msg_push_unspec(struct ofpbuf *msg, uint16_t type,
 328                   const void *data, size_t size)
 329 {
 330     memcpy(nl_msg_push_unspec_uninit(msg, type, size), data, size);
 331 }
 332
 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
 335  * Boolean flag.) */
 336 void
 337 nl_msg_push_flag(struct ofpbuf *msg, uint16_t type)
 338 {
 339     nl_msg_push_unspec(msg, type, NULL, 0);
 340 }
 341
 342 /* Prepends a Netlink attribute of the given 'type' and the given 8-bit 'value'
 343  * to 'msg'. */
 344 void
 345 nl_msg_push_u8(struct ofpbuf *msg, uint16_t type, uint8_t value)
 346 {
 347     nl_msg_push_unspec(msg, type, &value, sizeof value);
 348 }
 349
 350 /* Prepends a Netlink attribute of the given 'type' and the given 16-bit host
 351  * byte order 'value' to 'msg'. */
 352 void
 353 nl_msg_push_u16(struct ofpbuf *msg, uint16_t type, uint16_t value)
 354 {
 355     nl_msg_push_unspec(msg, type, &value, sizeof value);
 356 }
 357
 358 /* Prepends a Netlink attribute of the given 'type' and the given 32-bit host
 359  * byte order 'value' to 'msg'. */
 360 void
 361 nl_msg_push_u32(struct ofpbuf *msg, uint16_t type, uint32_t value)
 362 {
 363     nl_msg_push_unspec(msg, type, &value, sizeof value);
 364 }
 365
 366 /* Prepends a Netlink attribute of the given 'type' and the given 64-bit host
 367  * byte order 'value' to 'msg'. */
 368 void
 369 nl_msg_push_u64(struct ofpbuf *msg, uint16_t type, uint64_t value)
 370 {
 371     nl_msg_push_unspec(msg, type, &value, sizeof value);
 372 }
 373
 374 /* Prepends a Netlink attribute of the given 'type' and the given 16-bit
 375  * network byte order 'value' to 'msg'. */
 376 void
 377 nl_msg_push_be16(struct ofpbuf *msg, uint16_t type, ovs_be16 value)
 378 {
 379     nl_msg_push_unspec(msg, type, &value, sizeof value);
 380 }
 381
 382 /* Prepends a Netlink attribute of the given 'type' and the given 32-bit
 383  * network byte order 'value' to 'msg'. */
 384 void
 385 nl_msg_push_be32(struct ofpbuf *msg, uint16_t type, ovs_be32 value)
 386 {
 387     nl_msg_push_unspec(msg, type, &value, sizeof value);
 388 }
 389
 390 /* Prepends a Netlink attribute of the given 'type' and the given 64-bit
 391  * network byte order 'value' to 'msg'. */
 392 void
 393 nl_msg_push_be64(struct ofpbuf *msg, uint16_t type, ovs_be64 value)
 394 {
 395     nl_msg_push_unspec(msg, type, &value, sizeof value);
 396 }
 397
 398 /* Prepends a Netlink attribute of the given 'type' and the given
 399  * null-terminated string 'value' to 'msg'. */
 400 void
 401 nl_msg_push_string(struct ofpbuf *msg, uint16_t type, const char *value)
 402 {
 403     nl_msg_push_unspec(msg, type, value, strlen(value) + 1);
 404 }
 405
 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. */
 411 size_t
 412 nl_msg_start_nested(struct ofpbuf *msg, uint16_t type)
 413 {
 414     size_t offset = msg->size;
 415     nl_msg_put_unspec(msg, type, NULL, 0);
 416     return offset;
 417 }
 418
 419 /* Finalizes a nested Netlink attribute in 'msg'.  'offset' should be the value
 420  * returned by nl_msg_start_nested(). */
 421 void
 422 nl_msg_end_nested(struct ofpbuf *msg, size_t offset)
 423 {
 424     struct nlattr *attr = ofpbuf_at_assert(msg, offset, sizeof *attr);
 425     attr->nla_len = msg->size - offset;
 426 }
 427
 428 /* Appends a nested Netlink attribute of the given 'type', with the 'size'
 429  * bytes of content starting at 'data', to 'msg'. */
 430 void
 431 nl_msg_put_nested(struct ofpbuf *msg,
 432                   uint16_t type, const void *data, size_t size)
 433 {
 434     size_t offset = nl_msg_start_nested(msg, type);
 435     nl_msg_put(msg, data, size);
 436     nl_msg_end_nested(msg, offset);
 437 }
 438
 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.
 442  *
 443  * If 'buffer' does not begin with a "struct nlmsghdr" or begins with one that
 444  * is invalid, returns NULL without modifying 'buffer'. */
 445 struct nlmsghdr *
 446 nl_msg_next(struct ofpbuf *buffer, struct ofpbuf *msg)
 447 {
 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);
 454             return nlmsghdr;
 455         }
 456     }
 457
 458     msg->data = NULL;
 459     msg->size = 0;
 460     return NULL;
 461 }
 462 \f
 463 /* Attributes. */
 464
 465 /* Returns the bits of 'nla->nla_type' that are significant for determining its
 466  * type. */
 467 int
 468 nl_attr_type(const struct nlattr *nla)
 469 {
 470     return nla->nla_type & NLA_TYPE_MASK;
 471 }
 472
 473 /* Returns the first byte in the payload of attribute 'nla'. */
 474 const void *
 475 nl_attr_get(const struct nlattr *nla)
 476 {
 477     assert(nla->nla_len >= NLA_HDRLEN);
 478     return nla + 1;
 479 }
 480
 481 /* Returns the number of bytes in the payload of attribute 'nla'. */
 482 size_t
 483 nl_attr_get_size(const struct nlattr *nla)
 484 {
 485     assert(nla->nla_len >= NLA_HDRLEN);
 486     return nla->nla_len - NLA_HDRLEN;
 487 }
 488
 489 /* Asserts that 'nla''s payload is at least 'size' bytes long, and returns the
 490  * first byte of the payload. */
 491 const void *
 492 nl_attr_get_unspec(const struct nlattr *nla, size_t size)
 493 {
 494     assert(nla->nla_len >= NLA_HDRLEN + size);
 495     return nla + 1;
 496 }
 497
 498 /* Returns true if 'nla' is nonnull.  (Some Netlink protocols use the presence
 499  * or absence of an attribute as a Boolean flag.) */
 500 bool
 501 nl_attr_get_flag(const struct nlattr *nla)
 502 {
 503     return nla != NULL;
 504 }
 505
 506 #define NL_ATTR_GET_AS(NLA, TYPE) \
 507         (*(TYPE*) nl_attr_get_unspec(nla, sizeof(TYPE)))
 508
 509 /* Returns the 8-bit value in 'nla''s payload.
 510  *
 511  * Asserts that 'nla''s payload is at least 1 byte long. */
 512 uint8_t
 513 nl_attr_get_u8(const struct nlattr *nla)
 514 {
 515     return NL_ATTR_GET_AS(nla, uint8_t);
 516 }
 517
 518 /* Returns the 16-bit host byte order value in 'nla''s payload.
 519  *
 520  * Asserts that 'nla''s payload is at least 2 bytes long. */
 521 uint16_t
 522 nl_attr_get_u16(const struct nlattr *nla)
 523 {
 524     return NL_ATTR_GET_AS(nla, uint16_t);
 525 }
 526
 527 /* Returns the 32-bit host byte order value in 'nla''s payload.
 528  *
 529  * Asserts that 'nla''s payload is at least 4 bytes long. */
 530 uint32_t
 531 nl_attr_get_u32(const struct nlattr *nla)
 532 {
 533     return NL_ATTR_GET_AS(nla, uint32_t);
 534 }
 535
 536 /* Returns the 64-bit host byte order value in 'nla''s payload.
 537  *
 538  * Asserts that 'nla''s payload is at least 8 bytes long. */
 539 uint64_t
 540 nl_attr_get_u64(const struct nlattr *nla)
 541 {
 542     const ovs_32aligned_u64 *x = nl_attr_get_unspec(nla, sizeof *x);
 543     return get_32aligned_u64(x);
 544 }
 545
 546 /* Returns the 16-bit network byte order value in 'nla''s payload.
 547  *
 548  * Asserts that 'nla''s payload is at least 2 bytes long. */
 549 ovs_be16
 550 nl_attr_get_be16(const struct nlattr *nla)
 551 {
 552     return NL_ATTR_GET_AS(nla, ovs_be16);
 553 }
 554
 555 /* Returns the 32-bit network byte order value in 'nla''s payload.
 556  *
 557  * Asserts that 'nla''s payload is at least 4 bytes long. */
 558 ovs_be32
 559 nl_attr_get_be32(const struct nlattr *nla)
 560 {
 561     return NL_ATTR_GET_AS(nla, ovs_be32);
 562 }
 563
 564 /* Returns the 64-bit network byte order value in 'nla''s payload.
 565  *
 566  * Asserts that 'nla''s payload is at least 8 bytes long. */
 567 ovs_be64
 568 nl_attr_get_be64(const struct nlattr *nla)
 569 {
 570     const ovs_32aligned_be64 *x = nl_attr_get_unspec(nla, sizeof *x);
 571     return get_32aligned_be64(x);
 572 }
 573
 574 /* Returns the null-terminated string value in 'nla''s payload.
 575  *
 576  * Asserts that 'nla''s payload contains a null-terminated string. */
 577 const char *
 578 nl_attr_get_string(const struct nlattr *nla)
 579 {
 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);
 583 }
 584
 585 /* Initializes 'nested' to the payload of 'nla'. */
 586 void
 587 nl_attr_get_nested(const struct nlattr *nla, struct ofpbuf *nested)
 588 {
 589     ofpbuf_use_const(nested, nl_attr_get(nla), nl_attr_get_size(nla));
 590 }
 591
 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 },
 602 };
 603
 604 bool
 605 nl_attr_validate(const struct nlattr *nla, const struct nl_policy *policy)
 606 {
 607     uint16_t type = nl_attr_type(nla);
 608     size_t min_len;
 609     size_t max_len;
 610     size_t len;
 611
 612     if (policy->type == NL_A_NO_ATTR) {
 613         return true;
 614     }
 615
 616     /* Figure out min and max length. */
 617     min_len = policy->min_len;
 618     if (!min_len) {
 619         min_len = attr_len_range[policy->type][0];
 620     }
 621     max_len = policy->max_len;
 622     if (!max_len) {
 623         max_len = attr_len_range[policy->type][1];
 624     }
 625
 626     /* Verify length. */
 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);
 631         return false;
 632     }
 633
 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);
 638             return false;
 639         }
 640         if (memchr(nla + 1, '\0', len - 1) != NULL) {
 641             VLOG_DBG_RL(&rl, "attr %"PRIu16" has bad length", type);
 642             return false;
 643         }
 644     }
 645
 646     return true;
 647 }
 648
 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.
 653  *
 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. */
 656 bool
 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)
 660 {
 661     struct nlattr *nla;
 662     size_t left;
 663     size_t i;
 664
 665     memset(attrs, 0, n_attrs * sizeof *attrs);
 666
 667     if (msg->size < nla_offset) {
 668         VLOG_DBG_RL(&rl, "missing headers in nl_policy_parse");
 669         return false;
 670     }
 671
 672     NL_ATTR_FOR_EACH (nla, left,
 673                       (struct nlattr *) ((char *) msg->data + nla_offset),
 674                       msg->size - nla_offset)
 675     {
 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)) {
 680                 return false;
 681             }
 682             if (attrs[type]) {
 683                 VLOG_DBG_RL(&rl, "duplicate attr %"PRIu16, type);
 684             }
 685             attrs[type] = nla;
 686         }
 687     }
 688     if (left) {
 689         VLOG_DBG_RL(&rl, "attributes followed by garbage");
 690         return false;
 691     }
 692
 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);
 697             return false;
 698         }
 699     }
 700     return true;
 701 }
 702
 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
 706  * failure. */
 707 bool
 708 nl_parse_nested(const struct nlattr *nla, const struct nl_policy policy[],
 709                 struct nlattr *attrs[], size_t n_attrs)
 710 {
 711     struct ofpbuf buf;
 712
 713     nl_attr_get_nested(nla, &buf);
 714     return nl_policy_parse(&buf, 0, policy, attrs, n_attrs);
 715 }
 716
 717 const struct nlattr *
 718 nl_attr_find__(const struct nlattr *attrs, size_t size, uint16_t type)
 719 {
 720     const struct nlattr *nla;
 721     size_t left;
 722
 723     NL_ATTR_FOR_EACH (nla, left, attrs, size) {
 724         if (nl_attr_type(nla) == type) {
 725             return nla;
 726         }
 727     }
 728     return NULL;
 729 }
 730
 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'.
 733  *
 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)
 737 {
 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,
 740                           type);
 741 }
 742
 743 /* Returns the first Netlink attribute within 'nla' with the specified
 744  * 'type'.
 745  *
 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)
 749 {
 750     return nl_attr_find__(nl_attr_get(nla), nl_attr_get_size(nla), type);
 751 }