pimd/mtracebis_netlink.c

   1 /*
   2  * libnetlink.c RTnetlink service routines.
   3  *
   4  *              This program is free software; you can redistribute it and/or
   5  *              modify it under the terms of the GNU General Public License
   6  *              as published by the Free Software Foundation; either version
   7  *              2 of the License, or (at your option) any later version.
   8  *
   9  * Authors:     Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
  10  *
  11  */
  12
  13 #ifdef __linux__
  14
  15 #include <stdio.h>
  16 #include <stdlib.h>
  17 #include <unistd.h>
  18 #include <syslog.h>
  19 #include <fcntl.h>
  20 #include <net/if_arp.h>
  21 #include <sys/socket.h>
  22 #include <netinet/in.h>
  23 #include <string.h>
  24 #include <errno.h>
  25 #include <time.h>
  26 #include <sys/uio.h>
  27 #include <assert.h>
  28
  29 #include "mtracebis_netlink.h"
  30
  31 int rcvbuf = 1024 * 1024;
  32
  33 void rtnl_close(struct rtnl_handle *rth)
  34 {
  35         if (rth->fd >= 0) {
  36                 close(rth->fd);
  37                 rth->fd = -1;
  38         }
  39 }
  40
  41 int rtnl_open_byproto(struct rtnl_handle *rth, unsigned subscriptions,
  42                       int protocol)
  43 {
  44         socklen_t addr_len;
  45         int sndbuf = 32768;
  46
  47         memset(rth, 0, sizeof(*rth));
  48
  49         rth->fd = socket(AF_NETLINK, SOCK_RAW, protocol);
  50         if (rth->fd < 0) {
  51                 perror("Cannot open netlink socket");
  52                 return -1;
  53         }
  54
  55         if (setsockopt(rth->fd, SOL_SOCKET, SO_SNDBUF, &sndbuf, sizeof(sndbuf))
  56             < 0) {
  57                 perror("SO_SNDBUF");
  58                 return -1;
  59         }
  60
  61         if (setsockopt(rth->fd, SOL_SOCKET, SO_RCVBUF, &rcvbuf, sizeof(rcvbuf))
  62             < 0) {
  63                 perror("SO_RCVBUF");
  64                 return -1;
  65         }
  66
  67         memset(&rth->local, 0, sizeof(rth->local));
  68         rth->local.nl_family = AF_NETLINK;
  69         rth->local.nl_groups = subscriptions;
  70
  71         if (bind(rth->fd, (struct sockaddr *)&rth->local, sizeof(rth->local))
  72             < 0) {
  73                 perror("Cannot bind netlink socket");
  74                 return -1;
  75         }
  76         addr_len = sizeof(rth->local);
  77         if (getsockname(rth->fd, (struct sockaddr *)&rth->local, &addr_len)
  78             < 0) {
  79                 perror("Cannot getsockname");
  80                 return -1;
  81         }
  82         if (addr_len != sizeof(rth->local)) {
  83                 fprintf(stderr, "Wrong address length %d\n", addr_len);
  84                 return -1;
  85         }
  86         if (rth->local.nl_family != AF_NETLINK) {
  87                 fprintf(stderr, "Wrong address family %d\n",
  88                         rth->local.nl_family);
  89                 return -1;
  90         }
  91         rth->seq = time(NULL);
  92         return 0;
  93 }
  94
  95 int rtnl_open(struct rtnl_handle *rth, unsigned subscriptions)
  96 {
  97         return rtnl_open_byproto(rth, subscriptions, NETLINK_ROUTE);
  98 }
  99
 100 int rtnl_wilddump_request(struct rtnl_handle *rth, int family, int type)
 101 {
 102         struct {
 103                 struct nlmsghdr nlh;
 104                 struct rtgenmsg g;
 105         } req;
 106
 107         memset(&req, 0, sizeof(req));
 108         req.nlh.nlmsg_len = sizeof(req);
 109         req.nlh.nlmsg_type = type;
 110         req.nlh.nlmsg_flags = NLM_F_ROOT | NLM_F_MATCH | NLM_F_REQUEST;
 111         req.nlh.nlmsg_pid = 0;
 112         req.nlh.nlmsg_seq = rth->dump = ++rth->seq;
 113         req.g.rtgen_family = family;
 114
 115         return send(rth->fd, (void *)&req, sizeof(req), 0);
 116 }
 117
 118 int rtnl_send(struct rtnl_handle *rth, const char *buf, int len)
 119 {
 120         return send(rth->fd, buf, len, 0);
 121 }
 122
 123 int rtnl_send_check(struct rtnl_handle *rth, const char *buf, int len)
 124 {
 125         struct nlmsghdr *h;
 126         int status;
 127         char resp[1024];
 128
 129         status = send(rth->fd, buf, len, 0);
 130         if (status < 0)
 131                 return status;
 132
 133         /* Check for immediate errors */
 134         status = recv(rth->fd, resp, sizeof(resp), MSG_DONTWAIT | MSG_PEEK);
 135         if (status < 0) {
 136                 if (errno == EAGAIN)
 137                         return 0;
 138                 return -1;
 139         }
 140
 141         for (h = (struct nlmsghdr *)resp; NLMSG_OK(h, (uint32_t)status);
 142              h = NLMSG_NEXT(h, status)) {
 143                 if (h->nlmsg_type == NLMSG_ERROR) {
 144                         struct nlmsgerr *err = (struct nlmsgerr *)NLMSG_DATA(h);
 145                         if (h->nlmsg_len
 146                             < NLMSG_LENGTH(sizeof(struct nlmsgerr)))
 147                                 fprintf(stderr, "ERROR truncated\n");
 148                         else
 149                                 errno = -err->error;
 150                         return -1;
 151                 }
 152         }
 153
 154         return 0;
 155 }
 156
 157 int rtnl_dump_request(struct rtnl_handle *rth, int type, void *req, int len)
 158 {
 159         struct nlmsghdr nlh;
 160         struct sockaddr_nl nladdr;
 161         struct iovec iov[2] = {{.iov_base = &nlh, .iov_len = sizeof(nlh)},
 162                                {.iov_base = req, .iov_len = len}};
 163         struct msghdr msg = {
 164                 .msg_name = &nladdr,
 165                 .msg_namelen = sizeof(nladdr),
 166                 .msg_iov = iov,
 167                 .msg_iovlen = 2,
 168         };
 169
 170         memset(&nladdr, 0, sizeof(nladdr));
 171         nladdr.nl_family = AF_NETLINK;
 172
 173         nlh.nlmsg_len = NLMSG_LENGTH(len);
 174         nlh.nlmsg_type = type;
 175         nlh.nlmsg_flags = NLM_F_ROOT | NLM_F_MATCH | NLM_F_REQUEST;
 176         nlh.nlmsg_pid = 0;
 177         nlh.nlmsg_seq = rth->dump = ++rth->seq;
 178
 179         return sendmsg(rth->fd, &msg, 0);
 180 }
 181
 182 int rtnl_dump_filter_l(struct rtnl_handle *rth,
 183                        const struct rtnl_dump_filter_arg *arg)
 184 {
 185         struct sockaddr_nl nladdr;
 186         struct iovec iov;
 187         struct msghdr msg = {
 188                 .msg_name = &nladdr,
 189                 .msg_namelen = sizeof(nladdr),
 190                 .msg_iov = &iov,
 191                 .msg_iovlen = 1,
 192         };
 193         char buf[16384];
 194
 195         iov.iov_base = buf;
 196         while (1) {
 197                 int status;
 198                 const struct rtnl_dump_filter_arg *a;
 199                 int found_done = 0;
 200                 int msglen = 0;
 201
 202                 iov.iov_len = sizeof(buf);
 203                 status = recvmsg(rth->fd, &msg, 0);
 204
 205                 if (status < 0) {
 206                         if (errno == EINTR || errno == EAGAIN)
 207                                 continue;
 208                         fprintf(stderr, "netlink receive error %s (%d)\n",
 209                                 strerror(errno), errno);
 210                         return -1;
 211                 }
 212
 213                 if (status == 0) {
 214                         fprintf(stderr, "EOF on netlink\n");
 215                         return -1;
 216                 }
 217
 218                 for (a = arg; a->filter; a++) {
 219                         struct nlmsghdr *h = (struct nlmsghdr *)buf;
 220                         msglen = status;
 221
 222                         while (NLMSG_OK(h, (uint32_t)msglen)) {
 223                                 int err;
 224
 225                                 if (nladdr.nl_pid != 0
 226                                     || h->nlmsg_pid != rth->local.nl_pid
 227                                     || h->nlmsg_seq != rth->dump) {
 228                                         if (a->junk) {
 229                                                 err = a->junk(&nladdr, h,
 230                                                               a->arg2);
 231                                                 if (err < 0)
 232                                                         return err;
 233                                         }
 234                                         goto skip_it;
 235                                 }
 236
 237                                 if (h->nlmsg_type == NLMSG_DONE) {
 238                                         found_done = 1;
 239                                         break; /* process next filter */
 240                                 }
 241                                 if (h->nlmsg_type == NLMSG_ERROR) {
 242                                         struct nlmsgerr *err =
 243                                                 (struct nlmsgerr *)NLMSG_DATA(
 244                                                         h);
 245                                         if (h->nlmsg_len
 246                                             < NLMSG_LENGTH(sizeof(
 247                                                       struct nlmsgerr))) {
 248                                                 fprintf(stderr,
 249                                                         "ERROR truncated\n");
 250                                         } else {
 251                                                 errno = -err->error;
 252                                                 perror("RTNETLINK answers");
 253                                         }
 254                                         return -1;
 255                                 }
 256                                 err = a->filter(&nladdr, h, a->arg1);
 257                                 if (err < 0)
 258                                         return err;
 259
 260                         skip_it:
 261                                 h = NLMSG_NEXT(h, msglen);
 262                         }
 263                 }
 264
 265                 if (found_done)
 266                         return 0;
 267
 268                 if (msg.msg_flags & MSG_TRUNC) {
 269                         fprintf(stderr, "Message truncated\n");
 270                         continue;
 271                 }
 272                 if (msglen) {
 273                         fprintf(stderr, "!!!Remnant of size %d\n", msglen);
 274                         exit(1);
 275                 }
 276         }
 277 }
 278
 279 int rtnl_dump_filter(struct rtnl_handle *rth, rtnl_filter_t filter, void *arg1,
 280                      rtnl_filter_t junk, void *arg2)
 281 {
 282         const struct rtnl_dump_filter_arg a[2] = {
 283                 {.filter = filter, .arg1 = arg1, .junk = junk, .arg2 = arg2},
 284                 {.filter = NULL, .arg1 = NULL, .junk = NULL, .arg2 = NULL}};
 285
 286         return rtnl_dump_filter_l(rth, a);
 287 }
 288
 289 int rtnl_talk(struct rtnl_handle *rtnl, struct nlmsghdr *n, pid_t peer,
 290               unsigned groups, struct nlmsghdr *answer, rtnl_filter_t junk,
 291               void *jarg)
 292 {
 293         int status;
 294         unsigned seq;
 295         struct nlmsghdr *h;
 296         struct sockaddr_nl nladdr;
 297         struct iovec iov = {.iov_base = (void *)n, .iov_len = n->nlmsg_len};
 298         struct msghdr msg = {
 299                 .msg_name = &nladdr,
 300                 .msg_namelen = sizeof(nladdr),
 301                 .msg_iov = &iov,
 302                 .msg_iovlen = 1,
 303         };
 304         char buf[16384];
 305
 306         memset(&nladdr, 0, sizeof(nladdr));
 307         nladdr.nl_family = AF_NETLINK;
 308         nladdr.nl_pid = peer;
 309         nladdr.nl_groups = groups;
 310
 311         n->nlmsg_seq = seq = ++rtnl->seq;
 312
 313         if (answer == NULL)
 314                 n->nlmsg_flags |= NLM_F_ACK;
 315
 316         status = sendmsg(rtnl->fd, &msg, 0);
 317
 318         if (status < 0) {
 319                 perror("Cannot talk to rtnetlink");
 320                 return -1;
 321         }
 322
 323         memset(buf, 0, sizeof(buf));
 324
 325         iov.iov_base = buf;
 326
 327         while (1) {
 328                 iov.iov_len = sizeof(buf);
 329                 status = recvmsg(rtnl->fd, &msg, 0);
 330
 331                 if (status < 0) {
 332                         if (errno == EINTR || errno == EAGAIN)
 333                                 continue;
 334                         fprintf(stderr, "netlink receive error %s (%d)\n",
 335                                 strerror(errno), errno);
 336                         return -1;
 337                 }
 338                 if (status == 0) {
 339                         fprintf(stderr, "EOF on netlink\n");
 340                         return -1;
 341                 }
 342                 if (msg.msg_namelen != sizeof(nladdr)) {
 343                         fprintf(stderr, "sender address length == %d\n",
 344                                 msg.msg_namelen);
 345                         exit(1);
 346                 }
 347                 for (h = (struct nlmsghdr *)buf; status >= (int)sizeof(*h);) {
 348                         int err;
 349                         int len = h->nlmsg_len;
 350                         int l = len - sizeof(*h);
 351
 352                         if (l < 0 || len > status) {
 353                                 if (msg.msg_flags & MSG_TRUNC) {
 354                                         fprintf(stderr, "Truncated message\n");
 355                                         return -1;
 356                                 }
 357                                 fprintf(stderr,
 358                                         "!!!malformed message: len=%d\n", len);
 359                                 exit(1);
 360                         }
 361
 362                         if ((int)nladdr.nl_pid != peer
 363                             || h->nlmsg_pid != rtnl->local.nl_pid
 364                             || h->nlmsg_seq != seq) {
 365                                 if (junk) {
 366                                         err = junk(&nladdr, h, jarg);
 367                                         if (err < 0)
 368                                                 return err;
 369                                 }
 370                                 /* Don't forget to skip that message. */
 371                                 status -= NLMSG_ALIGN(len);
 372                                 h = (struct nlmsghdr *)((char *)h
 373                                                         + NLMSG_ALIGN(len));
 374                                 continue;
 375                         }
 376
 377                         if (h->nlmsg_type == NLMSG_ERROR) {
 378                                 struct nlmsgerr *err =
 379                                         (struct nlmsgerr *)NLMSG_DATA(h);
 380                                 if (l < (int)sizeof(struct nlmsgerr)) {
 381                                         fprintf(stderr, "ERROR truncated\n");
 382                                 } else {
 383                                         errno = -err->error;
 384                                         if (errno == 0) {
 385                                                 if (answer)
 386                                                         memcpy(answer, h,
 387                                                                h->nlmsg_len);
 388                                                 return 0;
 389                                         }
 390                                         perror("RTNETLINK answers");
 391                                 }
 392                                 return -1;
 393                         }
 394                         if (answer) {
 395                                 memcpy(answer, h, h->nlmsg_len);
 396                                 return 0;
 397                         }
 398
 399                         fprintf(stderr, "Unexpected reply!!!\n");
 400
 401                         status -= NLMSG_ALIGN(len);
 402                         h = (struct nlmsghdr *)((char *)h + NLMSG_ALIGN(len));
 403                 }
 404                 if (msg.msg_flags & MSG_TRUNC) {
 405                         fprintf(stderr, "Message truncated\n");
 406                         continue;
 407                 }
 408                 if (status) {
 409                         fprintf(stderr, "!!!Remnant of size %d\n", status);
 410                         exit(1);
 411                 }
 412         }
 413 }
 414
 415 int rtnl_listen(struct rtnl_handle *rtnl, rtnl_filter_t handler, void *jarg)
 416 {
 417         int status;
 418         struct nlmsghdr *h;
 419         struct sockaddr_nl nladdr;
 420         struct iovec iov;
 421         struct msghdr msg = {
 422                 .msg_name = &nladdr,
 423                 .msg_namelen = sizeof(nladdr),
 424                 .msg_iov = &iov,
 425                 .msg_iovlen = 1,
 426         };
 427         char buf[8192];
 428
 429         memset(&nladdr, 0, sizeof(nladdr));
 430         nladdr.nl_family = AF_NETLINK;
 431         nladdr.nl_pid = 0;
 432         nladdr.nl_groups = 0;
 433
 434         iov.iov_base = buf;
 435         while (1) {
 436                 iov.iov_len = sizeof(buf);
 437                 status = recvmsg(rtnl->fd, &msg, 0);
 438
 439                 if (status < 0) {
 440                         if (errno == EINTR || errno == EAGAIN)
 441                                 continue;
 442                         fprintf(stderr, "netlink receive error %s (%d)\n",
 443                                 strerror(errno), errno);
 444                         if (errno == ENOBUFS)
 445                                 continue;
 446                         return -1;
 447                 }
 448                 if (status == 0) {
 449                         fprintf(stderr, "EOF on netlink\n");
 450                         return -1;
 451                 }
 452                 if (msg.msg_namelen != sizeof(nladdr)) {
 453                         fprintf(stderr, "Sender address length == %d\n",
 454                                 msg.msg_namelen);
 455                         exit(1);
 456                 }
 457                 for (h = (struct nlmsghdr *)buf; status >= (int)sizeof(*h);) {
 458                         int err;
 459                         int len = h->nlmsg_len;
 460                         int l = len - sizeof(*h);
 461
 462                         if (l < 0 || len > status) {
 463                                 if (msg.msg_flags & MSG_TRUNC) {
 464                                         fprintf(stderr, "Truncated message\n");
 465                                         return -1;
 466                                 }
 467                                 fprintf(stderr,
 468                                         "!!!malformed message: len=%d\n", len);
 469                                 exit(1);
 470                         }
 471
 472                         err = handler(&nladdr, h, jarg);
 473                         if (err < 0)
 474                                 return err;
 475
 476                         status -= NLMSG_ALIGN(len);
 477                         h = (struct nlmsghdr *)((char *)h + NLMSG_ALIGN(len));
 478                 }
 479                 if (msg.msg_flags & MSG_TRUNC) {
 480                         fprintf(stderr, "Message truncated\n");
 481                         continue;
 482                 }
 483                 if (status) {
 484                         fprintf(stderr, "!!!Remnant of size %d\n", status);
 485                         exit(1);
 486                 }
 487         }
 488 }
 489
 490 int rtnl_from_file(FILE *rtnl, rtnl_filter_t handler, void *jarg)
 491 {
 492         struct sockaddr_nl nladdr;
 493         char buf[8192];
 494         struct nlmsghdr *h = (void *)buf;
 495
 496         memset(&nladdr, 0, sizeof(nladdr));
 497         nladdr.nl_family = AF_NETLINK;
 498         nladdr.nl_pid = 0;
 499         nladdr.nl_groups = 0;
 500
 501         while (1) {
 502                 int err;
 503                 size_t l, rl, arl;
 504
 505                 rl = sizeof(*h);
 506                 arl = fread(&buf, 1, rl, rtnl);
 507
 508                 if (arl != rl) {
 509                         if (arl == 0)
 510                                 return 0;
 511
 512                         if (ferror(rtnl))
 513                                 fprintf(stderr, "%s: header read failed\n",
 514                                         __func__);
 515                         else
 516                                 fprintf(stderr, "%s: truncated header\n",
 517                                         __func__);
 518                         return -1;
 519                 }
 520
 521                 l = h->nlmsg_len > rl ? h->nlmsg_len - rl : 0;
 522
 523                 if (l == 0 || (l + (size_t)NLMSG_HDRLEN) > sizeof(buf)) {
 524                         fprintf(stderr, "%s: malformed message: len=%zu @%lu\n",
 525                                 __func__, (size_t)h->nlmsg_len, ftell(rtnl));
 526                         return -1;
 527                 }
 528
 529                 rl = NLMSG_ALIGN(l);
 530                 arl = fread(NLMSG_DATA(h), 1, rl, rtnl);
 531
 532                 if (arl != rl) {
 533                         if (ferror(rtnl))
 534                                 fprintf(stderr, "%s: msg read failed\n",
 535                                         __func__);
 536                         else
 537                                 fprintf(stderr, "%s: truncated message\n",
 538                                         __func__);
 539                         return -1;
 540                 }
 541
 542                 err = handler(&nladdr, h, jarg);
 543                 if (err < 0)
 544                         return err;
 545         }
 546 }
 547
 548 int addattr32(struct nlmsghdr *n, int maxlen, int type, __u32 data)
 549 {
 550         int len = RTA_LENGTH(4);
 551         struct rtattr *rta;
 552         if ((int)(NLMSG_ALIGN(n->nlmsg_len) + len) > maxlen) {
 553                 fprintf(stderr,
 554                         "addattr32: Error! max allowed bound %d exceeded\n",
 555                         maxlen);
 556                 return -1;
 557         }
 558         rta = NLMSG_TAIL(n);
 559         rta->rta_type = type;
 560         rta->rta_len = len;
 561         memcpy(RTA_DATA(rta), &data, 4);
 562         n->nlmsg_len = NLMSG_ALIGN(n->nlmsg_len) + len;
 563         return 0;
 564 }
 565
 566 int addattr_l(struct nlmsghdr *n, int maxlen, int type, const void *data,
 567               int alen)
 568 {
 569         int len = RTA_LENGTH(alen);
 570         struct rtattr *rta;
 571
 572         if ((int)(NLMSG_ALIGN(n->nlmsg_len) + RTA_ALIGN(len)) > maxlen) {
 573                 fprintf(stderr,
 574                         "addattr_l ERROR: message exceeded bound of %d\n",
 575                         maxlen);
 576                 return -1;
 577         }
 578         rta = NLMSG_TAIL(n);
 579         rta->rta_type = type;
 580         rta->rta_len = len;
 581
 582         if (data)
 583                 memcpy(RTA_DATA(rta), data, alen);
 584         else
 585                 assert(alen == 0);
 586
 587         n->nlmsg_len = NLMSG_ALIGN(n->nlmsg_len) + RTA_ALIGN(len);
 588         return 0;
 589 }
 590
 591 int addraw_l(struct nlmsghdr *n, int maxlen, const void *data, int len)
 592 {
 593         if ((int)(NLMSG_ALIGN(n->nlmsg_len) + NLMSG_ALIGN(len)) > maxlen) {
 594                 fprintf(stderr,
 595                         "addraw_l ERROR: message exceeded bound of %d\n",
 596                         maxlen);
 597                 return -1;
 598         }
 599
 600         memcpy(NLMSG_TAIL(n), data, len);
 601         memset((uint8_t *)NLMSG_TAIL(n) + len, 0, NLMSG_ALIGN(len) - len);
 602         n->nlmsg_len = NLMSG_ALIGN(n->nlmsg_len) + NLMSG_ALIGN(len);
 603         return 0;
 604 }
 605
 606 struct rtattr *addattr_nest(struct nlmsghdr *n, int maxlen, int type)
 607 {
 608         struct rtattr *nest = NLMSG_TAIL(n);
 609
 610         addattr_l(n, maxlen, type, NULL, 0);
 611         return nest;
 612 }
 613
 614 int addattr_nest_end(struct nlmsghdr *n, struct rtattr *nest)
 615 {
 616         nest->rta_len = (uint8_t *)NLMSG_TAIL(n) - (uint8_t *)nest;
 617         return n->nlmsg_len;
 618 }
 619
 620 struct rtattr *addattr_nest_compat(struct nlmsghdr *n, int maxlen, int type,
 621                                    const void *data, int len)
 622 {
 623         struct rtattr *start = NLMSG_TAIL(n);
 624
 625         addattr_l(n, maxlen, type, data, len);
 626         addattr_nest(n, maxlen, type);
 627         return start;
 628 }
 629
 630 int addattr_nest_compat_end(struct nlmsghdr *n, struct rtattr *start)
 631 {
 632         struct rtattr *nest = start + NLMSG_ALIGN(start->rta_len);
 633
 634         start->rta_len = (uint8_t *)NLMSG_TAIL(n) - (uint8_t *)start;
 635         addattr_nest_end(n, nest);
 636         return n->nlmsg_len;
 637 }
 638
 639 int rta_addattr32(struct rtattr *rta, int maxlen, int type, __u32 data)
 640 {
 641         int len = RTA_LENGTH(4);
 642         struct rtattr *subrta;
 643
 644         if ((int)(RTA_ALIGN(rta->rta_len) + len) > maxlen) {
 645                 fprintf(stderr,
 646                         "rta_addattr32: Error! max allowed bound %d exceeded\n",
 647                         maxlen);
 648                 return -1;
 649         }
 650         subrta = (struct rtattr *)(((char *)rta) + RTA_ALIGN(rta->rta_len));
 651         subrta->rta_type = type;
 652         subrta->rta_len = len;
 653         memcpy(RTA_DATA(subrta), &data, 4);
 654         rta->rta_len = NLMSG_ALIGN(rta->rta_len) + len;
 655         return 0;
 656 }
 657
 658 int rta_addattr_l(struct rtattr *rta, int maxlen, int type, const void *data,
 659                   int alen)
 660 {
 661         struct rtattr *subrta;
 662         int len = RTA_LENGTH(alen);
 663
 664         if ((int)(RTA_ALIGN(rta->rta_len) + RTA_ALIGN(len)) > maxlen) {
 665                 fprintf(stderr,
 666                         "rta_addattr_l: Error! max allowed bound %d exceeded\n",
 667                         maxlen);
 668                 return -1;
 669         }
 670         subrta = (struct rtattr *)(((char *)rta) + RTA_ALIGN(rta->rta_len));
 671         subrta->rta_type = type;
 672         subrta->rta_len = len;
 673         memcpy(RTA_DATA(subrta), data, alen);
 674         rta->rta_len = NLMSG_ALIGN(rta->rta_len) + RTA_ALIGN(len);
 675         return 0;
 676 }
 677
 678 int parse_rtattr(struct rtattr *tb[], int max, struct rtattr *rta, int len)
 679 {
 680         memset(tb, 0, sizeof(struct rtattr *) * (max + 1));
 681         while (RTA_OK(rta, len)) {
 682                 if ((rta->rta_type <= max) && (!tb[rta->rta_type]))
 683                         tb[rta->rta_type] = rta;
 684                 rta = RTA_NEXT(rta, len);
 685         }
 686         if (len)
 687                 fprintf(stderr, "!!!Deficit %d, rta_len=%d\n", len,
 688                         rta->rta_len);
 689         return 0;
 690 }
 691
 692 int parse_rtattr_byindex(struct rtattr *tb[], int max, struct rtattr *rta,
 693                          int len)
 694 {
 695         int i = 0;
 696
 697         memset(tb, 0, sizeof(struct rtattr *) * max);
 698         while (RTA_OK(rta, len)) {
 699                 if (rta->rta_type <= max && i < max)
 700                         tb[i++] = rta;
 701                 rta = RTA_NEXT(rta, len);
 702         }
 703         if (len)
 704                 fprintf(stderr, "!!!Deficit %d, rta_len=%d\n", len,
 705                         rta->rta_len);
 706         return i;
 707 }
 708
 709 int __parse_rtattr_nested_compat(struct rtattr *tb[], int max,
 710                                  struct rtattr *rta, int len)
 711 {
 712         if ((int)RTA_PAYLOAD(rta) < len)
 713                 return -1;
 714         if (RTA_PAYLOAD(rta) >= RTA_ALIGN(len) + sizeof(struct rtattr)) {
 715                 rta = (struct rtattr *)(uint8_t *)RTA_DATA(rta)
 716                       + RTA_ALIGN(len);
 717                 return parse_rtattr_nested(tb, max, rta);
 718         }
 719         memset(tb, 0, sizeof(struct rtattr *) * (max + 1));
 720         return 0;
 721 }
 722
 723 #endif /* __linux__ */