lib/libnetlink.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 #include <stdio.h>
  14 #include <stdlib.h>
  15 #include <unistd.h>
  16 #include <syslog.h>
  17 #include <fcntl.h>
  18 #include <net/if_arp.h>
  19 #include <sys/socket.h>
  20 #include <netinet/in.h>
  21 #include <string.h>
  22 #include <errno.h>
  23 #include <time.h>
  24 #include <sys/uio.h>
  25
  26 #include "libnetlink.h"
  27
  28 void rtnl_close(struct rtnl_handle *rth)
  29 {
  30         close(rth->fd);
  31 }
  32
  33 int rtnl_open_byproto(struct rtnl_handle *rth, unsigned subscriptions, int protocol)
  34 {
  35         int addr_len;
  36         int sndbuf = 32768;
  37         int rcvbuf = 32768;
  38
  39         memset(rth, 0, sizeof(rth));
  40
  41         rth->fd = socket(AF_NETLINK, SOCK_RAW, protocol);
  42         if (rth->fd < 0) {
  43                 perror("Cannot open netlink socket");
  44                 return -1;
  45         }
  46
  47         if (setsockopt(rth->fd,SOL_SOCKET,SO_SNDBUF,&sndbuf,sizeof(sndbuf)) < 0) {
  48                 perror("SO_SNDBUF");
  49                 return -1;
  50         }
  51
  52         if (setsockopt(rth->fd,SOL_SOCKET,SO_RCVBUF,&rcvbuf,sizeof(rcvbuf)) < 0) {
  53                 perror("SO_RCVBUF");
  54                 return -1;
  55         }
  56
  57         memset(&rth->local, 0, sizeof(rth->local));
  58         rth->local.nl_family = AF_NETLINK;
  59         rth->local.nl_groups = subscriptions;
  60
  61         if (bind(rth->fd, (struct sockaddr*)&rth->local, sizeof(rth->local)) < 0) {
  62                 perror("Cannot bind netlink socket");
  63                 return -1;
  64         }
  65         addr_len = sizeof(rth->local);
  66         if (getsockname(rth->fd, (struct sockaddr*)&rth->local, &addr_len) < 0) {
  67                 perror("Cannot getsockname");
  68                 return -1;
  69         }
  70         if (addr_len != sizeof(rth->local)) {
  71                 fprintf(stderr, "Wrong address length %d\n", addr_len);
  72                 return -1;
  73         }
  74         if (rth->local.nl_family != AF_NETLINK) {
  75                 fprintf(stderr, "Wrong address family %d\n", rth->local.nl_family);
  76                 return -1;
  77         }
  78         rth->seq = time(NULL);
  79         return 0;
  80 }
  81
  82 int rtnl_open(struct rtnl_handle *rth, unsigned subscriptions)
  83 {
  84         return rtnl_open_byproto(rth, subscriptions, NETLINK_ROUTE);
  85 }
  86
  87 int rtnl_wilddump_request(struct rtnl_handle *rth, int family, int type)
  88 {
  89         struct {
  90                 struct nlmsghdr nlh;
  91                 struct rtgenmsg g;
  92         } req;
  93         struct sockaddr_nl nladdr;
  94
  95         memset(&nladdr, 0, sizeof(nladdr));
  96         nladdr.nl_family = AF_NETLINK;
  97
  98         req.nlh.nlmsg_len = sizeof(req);
  99         req.nlh.nlmsg_type = type;
 100         req.nlh.nlmsg_flags = NLM_F_ROOT|NLM_F_MATCH|NLM_F_REQUEST;
 101         req.nlh.nlmsg_pid = 0;
 102         req.nlh.nlmsg_seq = rth->dump = ++rth->seq;
 103         req.g.rtgen_family = family;
 104
 105         return sendto(rth->fd, (void*)&req, sizeof(req), 0, (struct sockaddr*)&nladdr, sizeof(nladdr));
 106 }
 107
 108 int rtnl_send(struct rtnl_handle *rth, const char *buf, int len)
 109 {
 110         struct sockaddr_nl nladdr;
 111
 112         memset(&nladdr, 0, sizeof(nladdr));
 113         nladdr.nl_family = AF_NETLINK;
 114
 115         return sendto(rth->fd, buf, len, 0, (struct sockaddr*)&nladdr, sizeof(nladdr));
 116 }
 117
 118 int rtnl_dump_request(struct rtnl_handle *rth, int type, void *req, int len)
 119 {
 120         struct nlmsghdr nlh;
 121         struct sockaddr_nl nladdr;
 122         struct iovec iov[2] = { { &nlh, sizeof(nlh) }, { req, len } };
 123         struct msghdr msg = {
 124                 (void*)&nladdr, sizeof(nladdr),
 125                 iov,    2,
 126                 NULL,   0,
 127                 0
 128         };
 129
 130         memset(&nladdr, 0, sizeof(nladdr));
 131         nladdr.nl_family = AF_NETLINK;
 132
 133         nlh.nlmsg_len = NLMSG_LENGTH(len);
 134         nlh.nlmsg_type = type;
 135         nlh.nlmsg_flags = NLM_F_ROOT|NLM_F_MATCH|NLM_F_REQUEST;
 136         nlh.nlmsg_pid = 0;
 137         nlh.nlmsg_seq = rth->dump = ++rth->seq;
 138
 139         return sendmsg(rth->fd, &msg, 0);
 140 }
 141
 142 int rtnl_dump_filter(struct rtnl_handle *rth,
 143                      rtnl_filter_t filter,
 144                      void *arg1,
 145                      rtnl_filter_t junk,
 146                      void *arg2)
 147 {
 148         char    buf[16384];
 149         struct sockaddr_nl nladdr;
 150         struct iovec iov = { buf, sizeof(buf) };
 151
 152         while (1) {
 153                 int status;
 154                 struct nlmsghdr *h;
 155
 156                 struct msghdr msg = {
 157                         (void*)&nladdr, sizeof(nladdr),
 158                         &iov,   1,
 159                         NULL,   0,
 160                         0
 161                 };
 162
 163                 status = recvmsg(rth->fd, &msg, 0);
 164
 165                 if (status < 0) {
 166                         if (errno == EINTR)
 167                                 continue;
 168                         perror("OVERRUN");
 169                         continue;
 170                 }
 171                 if (status == 0) {
 172                         fprintf(stderr, "EOF on netlink\n");
 173                         return -1;
 174                 }
 175                 if (msg.msg_namelen != sizeof(nladdr)) {
 176                         fprintf(stderr, "sender address length == %d\n", msg.msg_namelen);
 177                         exit(1);
 178                 }
 179
 180                 h = (struct nlmsghdr*)buf;
 181                 while (NLMSG_OK(h, status)) {
 182                         int err;
 183
 184                         if (nladdr.nl_pid != 0 ||
 185                             h->nlmsg_pid != rth->local.nl_pid ||
 186                             h->nlmsg_seq != rth->dump) {
 187                                 if (junk) {
 188                                         err = junk(&nladdr, h, arg2);
 189                                         if (err < 0)
 190                                                 return err;
 191                                 }
 192                                 goto skip_it;
 193                         }
 194
 195                         if (h->nlmsg_type == NLMSG_DONE)
 196                                 return 0;
 197                         if (h->nlmsg_type == NLMSG_ERROR) {
 198                                 struct nlmsgerr *err = (struct nlmsgerr*)NLMSG_DATA(h);
 199                                 if (h->nlmsg_len < NLMSG_LENGTH(sizeof(struct nlmsgerr))) {
 200                                         fprintf(stderr, "ERROR truncated\n");
 201                                 } else {
 202                                         errno = -err->error;
 203                                         perror("RTNETLINK answers");
 204                                 }
 205                                 return -1;
 206                         }
 207                         err = filter(&nladdr, h, arg1);
 208                         if (err < 0)
 209                                 return err;
 210
 211 skip_it:
 212                         h = NLMSG_NEXT(h, status);
 213                 }
 214                 if (msg.msg_flags & MSG_TRUNC) {
 215                         fprintf(stderr, "Message truncated\n");
 216                         continue;
 217                 }
 218                 if (status) {
 219                         fprintf(stderr, "!!!Remnant of size %d\n", status);
 220                         exit(1);
 221                 }
 222         }
 223 }
 224
 225 int rtnl_talk(struct rtnl_handle *rtnl, struct nlmsghdr *n, pid_t peer,
 226               unsigned groups, struct nlmsghdr *answer,
 227               rtnl_filter_t junk,
 228               void *jarg)
 229 {
 230         int status;
 231         unsigned seq;
 232         struct nlmsghdr *h;
 233         struct sockaddr_nl nladdr;
 234         struct iovec iov = { (void*)n, n->nlmsg_len };
 235         char   buf[16384];
 236         struct msghdr msg = {
 237                 (void*)&nladdr, sizeof(nladdr),
 238                 &iov,   1,
 239                 NULL,   0,
 240                 0
 241         };
 242
 243         memset(&nladdr, 0, sizeof(nladdr));
 244         nladdr.nl_family = AF_NETLINK;
 245         nladdr.nl_pid = peer;
 246         nladdr.nl_groups = groups;
 247
 248         n->nlmsg_seq = seq = ++rtnl->seq;
 249
 250         if (answer == NULL)
 251                 n->nlmsg_flags |= NLM_F_ACK;
 252
 253         status = sendmsg(rtnl->fd, &msg, 0);
 254
 255         if (status < 0) {
 256                 perror("Cannot talk to rtnetlink");
 257                 return -1;
 258         }
 259
 260         memset(buf,0,sizeof(buf));
 261
 262         iov.iov_base = buf;
 263
 264         while (1) {
 265                 iov.iov_len = sizeof(buf);
 266                 status = recvmsg(rtnl->fd, &msg, 0);
 267
 268                 if (status < 0) {
 269                         if (errno == EINTR)
 270                                 continue;
 271                         perror("OVERRUN");
 272                         continue;
 273                 }
 274                 if (status == 0) {
 275                         fprintf(stderr, "EOF on netlink\n");
 276                         return -1;
 277                 }
 278                 if (msg.msg_namelen != sizeof(nladdr)) {
 279                         fprintf(stderr, "sender address length == %d\n", msg.msg_namelen);
 280                         exit(1);
 281                 }
 282                 for (h = (struct nlmsghdr*)buf; status >= sizeof(*h); ) {
 283                         int err;
 284                         int len = h->nlmsg_len;
 285                         int l = len - sizeof(*h);
 286
 287                         if (l<0 || len>status) {
 288                                 if (msg.msg_flags & MSG_TRUNC) {
 289                                         fprintf(stderr, "Truncated message\n");
 290                                         return -1;
 291                                 }
 292                                 fprintf(stderr, "!!!malformed message: len=%d\n", len);
 293                                 exit(1);
 294                         }
 295
 296                         if (nladdr.nl_pid != peer ||
 297                             h->nlmsg_pid != rtnl->local.nl_pid ||
 298                             h->nlmsg_seq != seq) {
 299                                 if (junk) {
 300                                         err = junk(&nladdr, h, jarg);
 301                                         if (err < 0)
 302                                                 return err;
 303                                 }
 304                                 continue;
 305                         }
 306
 307                         if (h->nlmsg_type == NLMSG_ERROR) {
 308                                 struct nlmsgerr *err = (struct nlmsgerr*)NLMSG_DATA(h);
 309                                 if (l < sizeof(struct nlmsgerr)) {
 310                                         fprintf(stderr, "ERROR truncated\n");
 311                                 } else {
 312                                         errno = -err->error;
 313                                         if (errno == 0) {
 314                                                 if (answer)
 315                                                         memcpy(answer, h, h->nlmsg_len);
 316                                                 return 0;
 317                                         }
 318                                         perror("RTNETLINK answers");
 319                                 }
 320                                 return -1;
 321                         }
 322                         if (answer) {
 323                                 memcpy(answer, h, h->nlmsg_len);
 324                                 return 0;
 325                         }
 326
 327                         fprintf(stderr, "Unexpected reply!!!\n");
 328
 329                         status -= NLMSG_ALIGN(len);
 330                         h = (struct nlmsghdr*)((char*)h + NLMSG_ALIGN(len));
 331                 }
 332                 if (msg.msg_flags & MSG_TRUNC) {
 333                         fprintf(stderr, "Message truncated\n");
 334                         continue;
 335                 }
 336                 if (status) {
 337                         fprintf(stderr, "!!!Remnant of size %d\n", status);
 338                         exit(1);
 339                 }
 340         }
 341 }
 342
 343 int rtnl_listen(struct rtnl_handle *rtnl,
 344                 rtnl_filter_t handler,
 345                 void *jarg)
 346 {
 347         int status;
 348         struct nlmsghdr *h;
 349         struct sockaddr_nl nladdr;
 350         struct iovec iov;
 351         char   buf[8192];
 352         struct msghdr msg = {
 353                 (void*)&nladdr, sizeof(nladdr),
 354                 &iov,   1,
 355                 NULL,   0,
 356                 0
 357         };
 358
 359         memset(&nladdr, 0, sizeof(nladdr));
 360         nladdr.nl_family = AF_NETLINK;
 361         nladdr.nl_pid = 0;
 362         nladdr.nl_groups = 0;
 363
 364
 365         iov.iov_base = buf;
 366
 367         while (1) {
 368                 iov.iov_len = sizeof(buf);
 369                 status = recvmsg(rtnl->fd, &msg, 0);
 370
 371                 if (status < 0) {
 372                         if (errno == EINTR)
 373                                 continue;
 374                         perror("OVERRUN");
 375                         continue;
 376                 }
 377                 if (status == 0) {
 378                         fprintf(stderr, "EOF on netlink\n");
 379                         return -1;
 380                 }
 381                 if (msg.msg_namelen != sizeof(nladdr)) {
 382                         fprintf(stderr, "Sender address length == %d\n", msg.msg_namelen);
 383                         exit(1);
 384                 }
 385                 for (h = (struct nlmsghdr*)buf; status >= sizeof(*h); ) {
 386                         int err;
 387                         int len = h->nlmsg_len;
 388                         int l = len - sizeof(*h);
 389
 390                         if (l<0 || len>status) {
 391                                 if (msg.msg_flags & MSG_TRUNC) {
 392                                         fprintf(stderr, "Truncated message\n");
 393                                         return -1;
 394                                 }
 395                                 fprintf(stderr, "!!!malformed message: len=%d\n", len);
 396                                 exit(1);
 397                         }
 398
 399                         err = handler(&nladdr, h, jarg);
 400                         if (err < 0)
 401                                 return err;
 402
 403                         status -= NLMSG_ALIGN(len);
 404                         h = (struct nlmsghdr*)((char*)h + NLMSG_ALIGN(len));
 405                 }
 406                 if (msg.msg_flags & MSG_TRUNC) {
 407                         fprintf(stderr, "Message truncated\n");
 408                         continue;
 409                 }
 410                 if (status) {
 411                         fprintf(stderr, "!!!Remnant of size %d\n", status);
 412                         exit(1);
 413                 }
 414         }
 415 }
 416
 417 int rtnl_from_file(FILE *rtnl, rtnl_filter_t handler,
 418                    void *jarg)
 419 {
 420         int status;
 421         struct sockaddr_nl nladdr;
 422         char   buf[8192];
 423         struct nlmsghdr *h = (void*)buf;
 424
 425         memset(&nladdr, 0, sizeof(nladdr));
 426         nladdr.nl_family = AF_NETLINK;
 427         nladdr.nl_pid = 0;
 428         nladdr.nl_groups = 0;
 429
 430         while (1) {
 431                 int err, len, type;
 432                 int l;
 433
 434                 status = fread(&buf, 1, sizeof(*h), rtnl);
 435
 436                 if (status < 0) {
 437                         if (errno == EINTR)
 438                                 continue;
 439                         perror("rtnl_from_file: fread");
 440                         return -1;
 441                 }
 442                 if (status == 0)
 443                         return 0;
 444
 445                 len = h->nlmsg_len;
 446                 type= h->nlmsg_type;
 447                 l = len - sizeof(*h);
 448
 449                 if (l<0 || len>sizeof(buf)) {
 450                         fprintf(stderr, "!!!malformed message: len=%d @%lu\n",
 451                                 len, ftell(rtnl));
 452                         return -1;
 453                 }
 454
 455                 status = fread(NLMSG_DATA(h), 1, NLMSG_ALIGN(l), rtnl);
 456
 457                 if (status < 0) {
 458                         perror("rtnl_from_file: fread");
 459                         return -1;
 460                 }
 461                 if (status < l) {
 462                         fprintf(stderr, "rtnl-from_file: truncated message\n");
 463                         return -1;
 464                 }
 465
 466                 err = handler(&nladdr, h, jarg);
 467                 if (err < 0)
 468                         return err;
 469         }
 470 }
 471
 472 int addattr32(struct nlmsghdr *n, int maxlen, int type, __u32 data)
 473 {
 474         int len = RTA_LENGTH(4);
 475         struct rtattr *rta;
 476         if (NLMSG_ALIGN(n->nlmsg_len) + len > maxlen) {
 477                 fprintf(stderr,"addattr32: Error! max allowed bound %d exceeded\n",maxlen);
 478                 return -1;
 479         }
 480         rta = NLMSG_TAIL(n);
 481         rta->rta_type = type;
 482         rta->rta_len = len;
 483         memcpy(RTA_DATA(rta), &data, 4);
 484         n->nlmsg_len = NLMSG_ALIGN(n->nlmsg_len) + len;
 485         return 0;
 486 }
 487
 488 int addattr_l(struct nlmsghdr *n, int maxlen, int type, const void *data,
 489               int alen)
 490 {
 491         int len = RTA_LENGTH(alen);
 492         struct rtattr *rta;
 493
 494         if (NLMSG_ALIGN(n->nlmsg_len) + len > maxlen) {
 495                 fprintf(stderr, "addattr_l ERROR: message exceeded bound of %d\n",maxlen);
 496                 return -1;
 497         }
 498         rta = NLMSG_TAIL(n);
 499         rta->rta_type = type;
 500         rta->rta_len = len;
 501         memcpy(RTA_DATA(rta), data, alen);
 502         n->nlmsg_len = NLMSG_ALIGN(n->nlmsg_len) + len;
 503         return 0;
 504 }
 505
 506 int addraw_l(struct nlmsghdr *n, int maxlen, const void *data, int len)
 507 {
 508         if (NLMSG_ALIGN(n->nlmsg_len) + NLMSG_ALIGN(len) > maxlen) {
 509                 fprintf(stderr, "addraw_l ERROR: message exceeded bound of %d\n",maxlen);
 510                 return -1;
 511         }
 512
 513         memcpy(NLMSG_TAIL(n), data, len);
 514         memset((void *) NLMSG_TAIL(n) + len, 0, NLMSG_ALIGN(len) - len);
 515         n->nlmsg_len = NLMSG_ALIGN(n->nlmsg_len) + NLMSG_ALIGN(len);
 516         return 0;
 517 }
 518
 519 int rta_addattr32(struct rtattr *rta, int maxlen, int type, __u32 data)
 520 {
 521         int len = RTA_LENGTH(4);
 522         struct rtattr *subrta;
 523
 524         if (RTA_ALIGN(rta->rta_len) + len > maxlen) {
 525                 fprintf(stderr,"rta_addattr32: Error! max allowed bound %d exceeded\n",maxlen);
 526                 return -1;
 527         }
 528         subrta = (struct rtattr*)(((char*)rta) + RTA_ALIGN(rta->rta_len));
 529         subrta->rta_type = type;
 530         subrta->rta_len = len;
 531         memcpy(RTA_DATA(subrta), &data, 4);
 532         rta->rta_len = NLMSG_ALIGN(rta->rta_len) + len;
 533         return 0;
 534 }
 535
 536 int rta_addattr_l(struct rtattr *rta, int maxlen, int type,
 537                   const void *data, int alen)
 538 {
 539         struct rtattr *subrta;
 540         int len = RTA_LENGTH(alen);
 541
 542         if (RTA_ALIGN(rta->rta_len) + len > maxlen) {
 543                 fprintf(stderr,"rta_addattr_l: Error! max allowed bound %d exceeded\n",maxlen);
 544                 return -1;
 545         }
 546         subrta = (struct rtattr*)(((char*)rta) + RTA_ALIGN(rta->rta_len));
 547         subrta->rta_type = type;
 548         subrta->rta_len = len;
 549         memcpy(RTA_DATA(subrta), data, alen);
 550         rta->rta_len = NLMSG_ALIGN(rta->rta_len) + len;
 551         return 0;
 552 }
 553
 554 int parse_rtattr(struct rtattr *tb[], int max, struct rtattr *rta, int len)
 555 {
 556         memset(tb, 0, sizeof(struct rtattr *) * (max + 1));
 557         while (RTA_OK(rta, len)) {
 558                 if (rta->rta_type <= max)
 559                         tb[rta->rta_type] = rta;
 560                 rta = RTA_NEXT(rta,len);
 561         }
 562         if (len)
 563                 fprintf(stderr, "!!!Deficit %d, rta_len=%d\n", len, rta->rta_len);
 564         return 0;
 565 }
 566
 567 int parse_rtattr_byindex(struct rtattr *tb[], int max, struct rtattr *rta, int len)
 568 {
 569         int i = 0;
 570
 571         memset(tb, 0, sizeof(struct rtattr *) * max);
 572         while (RTA_OK(rta, len)) {
 573                 if (rta->rta_type <= max && i < max)
 574                         tb[i++] = rta;
 575                 rta = RTA_NEXT(rta,len);
 576         }
 577         if (len)
 578                 fprintf(stderr, "!!!Deficit %d, rta_len=%d\n", len, rta->rta_len);
 579         return i;
 580 }