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  * Modified by Ted Felix (www.tedfelix.com) to fix warnings.
  12  *
  13  */
  14
  15 #include <stdio.h>
  16 #include <stdlib.h>
  17 #include <unistd.h>
  18 #include <fcntl.h>
  19 #include <net/if_arp.h>
  20 #include <sys/socket.h>
  21 #include <netinet/in.h>
  22 #include <string.h>
  23 #include <errno.h>
  24 #include <time.h>
  25 #include <sys/uio.h>
  26
  27 #include "libnetlink.h"
  28
  29 void rtnl_close(struct rtnl_handle *rth)
  30 {
  31         if (rth->fd >= 0) {
  32                 close(rth->fd);
  33                 rth->fd = -1;
  34         }
  35 }
  36
  37 int rtnl_open_byproto(struct rtnl_handle *rth, unsigned subscriptions,
  38                       int protocol)
  39 {
  40         socklen_t addr_len;
  41         int sndbuf = 32768;
  42         int rcvbuf = 32768;
  43
  44         memset(rth, 0, sizeof(rth));
  45
  46         rth->fd = socket(AF_NETLINK, SOCK_RAW, protocol);
  47         if (rth->fd < 0) {
  48                 perror("Cannot open netlink socket");
  49                 return -1;
  50         }
  51
  52         if (setsockopt(rth->fd,SOL_SOCKET,SO_SNDBUF,&sndbuf,sizeof(sndbuf)) < 0) {
  53                 perror("SO_SNDBUF");
  54                 return -1;
  55         }
  56
  57         if (setsockopt(rth->fd,SOL_SOCKET,SO_RCVBUF,&rcvbuf,sizeof(rcvbuf)) < 0) {
  58                 perror("SO_RCVBUF");
  59                 return -1;
  60         }
  61
  62         memset(&rth->local, 0, sizeof(rth->local));
  63         rth->local.nl_family = AF_NETLINK;
  64         rth->local.nl_groups = subscriptions;
  65
  66         if (bind(rth->fd, (struct sockaddr*)&rth->local, sizeof(rth->local)) < 0) {
  67                 perror("Cannot bind netlink socket");
  68                 return -1;
  69         }
  70         addr_len = sizeof(rth->local);
  71         if (getsockname(rth->fd, (struct sockaddr*)&rth->local, &addr_len) < 0) {
  72                 perror("Cannot getsockname");
  73                 return -1;
  74         }
  75         if (addr_len != sizeof(rth->local)) {
  76                 fprintf(stderr, "Wrong address length %d\n", addr_len);
  77                 return -1;
  78         }
  79         if (rth->local.nl_family != AF_NETLINK) {
  80                 fprintf(stderr, "Wrong address family %d\n", rth->local.nl_family);
  81                 return -1;
  82         }
  83         rth->seq = time(NULL);
  84         return 0;
  85 }
  86
  87 int rtnl_open(struct rtnl_handle *rth, unsigned subscriptions)
  88 {
  89         return rtnl_open_byproto(rth, subscriptions, NETLINK_ROUTE);
  90 }
  91
  92 int rtnl_wilddump_request(struct rtnl_handle *rth, int family, int type)
  93 {
  94         struct {
  95                 struct nlmsghdr nlh;
  96                 struct rtgenmsg g;
  97         } req;
  98         struct sockaddr_nl nladdr;
  99
 100         memset(&nladdr, 0, sizeof(nladdr));
 101         nladdr.nl_family = AF_NETLINK;
 102
 103         memset(&req, 0, sizeof(req));
 104         req.nlh.nlmsg_len = sizeof(req);
 105         req.nlh.nlmsg_type = type;
 106         req.nlh.nlmsg_flags = NLM_F_ROOT|NLM_F_MATCH|NLM_F_REQUEST;
 107         req.nlh.nlmsg_pid = 0;
 108         req.nlh.nlmsg_seq = rth->dump = ++rth->seq;
 109         req.g.rtgen_family = family;
 110
 111         return sendto(rth->fd, (void*)&req, sizeof(req), 0,
 112                       (struct sockaddr*)&nladdr, sizeof(nladdr));
 113 }
 114
 115 int rtnl_send(struct rtnl_handle *rth, const char *buf, int len)
 116 {
 117         struct sockaddr_nl nladdr;
 118
 119         memset(&nladdr, 0, sizeof(nladdr));
 120         nladdr.nl_family = AF_NETLINK;
 121
 122         return sendto(rth->fd, buf, len, 0, (struct sockaddr*)&nladdr, sizeof(nladdr));
 123 }
 124
 125 int rtnl_dump_request(struct rtnl_handle *rth, int type, void *req, int len)
 126 {
 127         struct nlmsghdr nlh;
 128         struct sockaddr_nl nladdr;
 129         struct iovec iov[2] = {
 130                 { .iov_base = &nlh, .iov_len = sizeof(nlh) },
 131                 { .iov_base = req, .iov_len = len }
 132         };
 133         struct msghdr msg = {
 134                 .msg_name = &nladdr,
 135                 .msg_namelen =  sizeof(nladdr),
 136                 .msg_iov = iov,
 137                 .msg_iovlen = 2,
 138         };
 139
 140         memset(&nladdr, 0, sizeof(nladdr));
 141         nladdr.nl_family = AF_NETLINK;
 142
 143         nlh.nlmsg_len = NLMSG_LENGTH(len);
 144         nlh.nlmsg_type = type;
 145         nlh.nlmsg_flags = NLM_F_ROOT|NLM_F_MATCH|NLM_F_REQUEST;
 146         nlh.nlmsg_pid = 0;
 147         nlh.nlmsg_seq = rth->dump = ++rth->seq;
 148
 149         return sendmsg(rth->fd, &msg, 0);
 150 }
 151
 152 int rtnl_dump_filter(struct rtnl_handle *rth,
 153                      rtnl_filter_t filter,
 154                      void *arg1,
 155                      rtnl_filter_t junk,
 156                      void *arg2)
 157 {
 158         struct sockaddr_nl nladdr;
 159         struct iovec iov;
 160         struct msghdr msg = {
 161                 .msg_name = &nladdr,
 162                 .msg_namelen = sizeof(nladdr),
 163                 .msg_iov = &iov,
 164                 .msg_iovlen = 1,
 165         };
 166         char buf[16384];
 167
 168         iov.iov_base = buf;
 169         while (1) {
 170                 int status;
 171                 struct nlmsghdr *h;
 172
 173                 iov.iov_len = sizeof(buf);
 174                 status = recvmsg(rth->fd, &msg, 0);
 175
 176                 if (status < 0) {
 177                         if (errno == EINTR)
 178                                 continue;
 179                         perror("OVERRUN");
 180                         continue;
 181                 }
 182
 183                 if (status == 0) {
 184                         fprintf(stderr, "EOF on netlink\n");
 185                         return -1;
 186                 }
 187
 188                 h = (struct nlmsghdr*)buf;
 189                 while (NLMSG_OK(h, (unsigned)status)) {
 190                         int err;
 191
 192                         if (nladdr.nl_pid != 0 ||
 193                             h->nlmsg_pid != rth->local.nl_pid ||
 194                             h->nlmsg_seq != rth->dump) {
 195                                 if (junk) {
 196                                         err = junk(&nladdr, h, arg2);
 197                                         if (err < 0)
 198                                                 return err;
 199                                 }
 200                                 goto skip_it;
 201                         }
 202
 203                         if (h->nlmsg_type == NLMSG_DONE)
 204                                 return 0;
 205                         if (h->nlmsg_type == NLMSG_ERROR) {
 206                                 struct nlmsgerr *msgerr = (struct nlmsgerr*)NLMSG_DATA(h);
 207                                 if (h->nlmsg_len < NLMSG_LENGTH(sizeof(struct nlmsgerr))) {
 208                                         fprintf(stderr, "ERROR truncated\n");
 209                                 } else {
 210                                         errno = -msgerr->error;
 211                                         perror("RTNETLINK answers");
 212                                 }
 213                                 return -1;
 214                         }
 215                         err = filter(&nladdr, h, arg1);
 216                         if (err < 0)
 217                                 return err;
 218
 219 skip_it:
 220                         h = NLMSG_NEXT(h, status);
 221                 }
 222                 if (msg.msg_flags & MSG_TRUNC) {
 223                         fprintf(stderr, "Message truncated\n");
 224                         continue;
 225                 }
 226                 if (status) {
 227                         fprintf(stderr, "!!!Remnant of size %d\n", status);
 228                         exit(1);
 229                 }
 230         }
 231 }
 232
 233 int rtnl_talk(struct rtnl_handle *rtnl, struct nlmsghdr *n, pid_t peer,
 234               unsigned groups, struct nlmsghdr *answer,
 235               rtnl_filter_t junk,
 236               void *jarg)
 237 {
 238         int status;
 239         unsigned seq;
 240         struct nlmsghdr *h;
 241         struct sockaddr_nl nladdr;
 242         struct iovec iov = {
 243                 .iov_base = (void*) n,
 244                 .iov_len = n->nlmsg_len
 245         };
 246         struct msghdr msg = {
 247                 .msg_name = &nladdr,
 248                 .msg_namelen = sizeof(nladdr),
 249                 .msg_iov = &iov,
 250                 .msg_iovlen = 1,
 251         };
 252         char   buf[16384];
 253
 254         memset(&nladdr, 0, sizeof(nladdr));
 255         nladdr.nl_family = AF_NETLINK;
 256         nladdr.nl_pid = peer;
 257         nladdr.nl_groups = groups;
 258
 259         n->nlmsg_seq = seq = ++rtnl->seq;
 260
 261         if (answer == NULL)
 262                 n->nlmsg_flags |= NLM_F_ACK;
 263
 264         status = sendmsg(rtnl->fd, &msg, 0);
 265
 266         if (status < 0) {
 267                 perror("Cannot talk to rtnetlink");
 268                 return -1;
 269         }
 270
 271         memset(buf,0,sizeof(buf));
 272
 273         iov.iov_base = buf;
 274
 275         while (1) {
 276                 iov.iov_len = sizeof(buf);
 277                 status = recvmsg(rtnl->fd, &msg, 0);
 278
 279                 if (status < 0) {
 280                         if (errno == EINTR)
 281                                 continue;
 282                         perror("OVERRUN");
 283                         continue;
 284                 }
 285                 if (status == 0) {
 286                         fprintf(stderr, "EOF on netlink\n");
 287                         return -1;
 288                 }
 289                 if (msg.msg_namelen != sizeof(nladdr)) {
 290                         fprintf(stderr, "sender address length == %d\n", msg.msg_namelen);
 291                         exit(1);
 292                 }
 293                 for (h = (struct nlmsghdr*)buf; (unsigned)status >= sizeof(*h); ) {
 294                         int err;
 295                         int len = h->nlmsg_len;
 296                         int l = len - sizeof(*h);
 297
 298                         if (l<0 || len>status) {
 299                                 if (msg.msg_flags & MSG_TRUNC) {
 300                                         fprintf(stderr, "Truncated message\n");
 301                                         return -1;
 302                                 }
 303                                 fprintf(stderr, "!!!malformed message: len=%d\n", len);
 304                                 exit(1);
 305                         }
 306
 307                         if (nladdr.nl_pid != (unsigned)peer ||
 308                             h->nlmsg_pid != rtnl->local.nl_pid ||
 309                             h->nlmsg_seq != seq) {
 310                                 if (junk) {
 311                                         err = junk(&nladdr, h, jarg);
 312                                         if (err < 0)
 313                                                 return err;
 314                                 }
 315                                 /* Don't forget to skip that message. */
 316                                 status -= NLMSG_ALIGN(len);
 317                                 h = (struct nlmsghdr*)((char*)h + NLMSG_ALIGN(len));
 318                                 continue;
 319                         }
 320
 321                         if (h->nlmsg_type == NLMSG_ERROR) {
 322                                 struct nlmsgerr *msgerr = (struct nlmsgerr*)NLMSG_DATA(h);
 323                                 if ((unsigned)l < sizeof(struct nlmsgerr)) {
 324                                         fprintf(stderr, "ERROR truncated\n");
 325                                 } else {
 326                                         errno = -msgerr->error;
 327                                         if (errno == 0) {
 328                                                 if (answer)
 329                                                         memcpy(answer, h, h->nlmsg_len);
 330                                                 return 0;
 331                                         }
 332                                         perror("RTNETLINK1 answers");
 333                                 }
 334                                 return -1;
 335                         }
 336                         if (answer) {
 337                                 memcpy(answer, h, h->nlmsg_len);
 338                                 return 0;
 339                         }
 340
 341                         fprintf(stderr, "Unexpected reply!!!\n");
 342
 343                         status -= NLMSG_ALIGN(len);
 344                         h = (struct nlmsghdr*)((char*)h + NLMSG_ALIGN(len));
 345                 }
 346                 if (msg.msg_flags & MSG_TRUNC) {
 347                         fprintf(stderr, "Message truncated\n");
 348                         continue;
 349                 }
 350                 if (status) {
 351                         fprintf(stderr, "!!!Remnant of size %d\n", status);
 352                         exit(1);
 353                 }
 354         }
 355 }
 356
 357 int rtnl_listen(struct rtnl_handle *rtnl,
 358                 rtnl_filter_t handler,
 359                 void *jarg)
 360 {
 361         int status;
 362         struct nlmsghdr *h;
 363         struct sockaddr_nl nladdr;
 364         struct iovec iov;
 365         struct msghdr msg = {
 366                 .msg_name = &nladdr,
 367                 .msg_namelen = sizeof(nladdr),
 368                 .msg_iov = &iov,
 369                 .msg_iovlen = 1,
 370         };
 371         char   buf[8192];
 372
 373         memset(&nladdr, 0, sizeof(nladdr));
 374         nladdr.nl_family = AF_NETLINK;
 375         nladdr.nl_pid = 0;
 376         nladdr.nl_groups = 0;
 377
 378         iov.iov_base = buf;
 379         while (1) {
 380                 iov.iov_len = sizeof(buf);
 381                 status = recvmsg(rtnl->fd, &msg, 0);
 382
 383                 if (status < 0) {
 384                         if (errno == EINTR)
 385                                 continue;
 386                         perror("OVERRUN");
 387                         continue;
 388                 }
 389                 if (status == 0) {
 390                         fprintf(stderr, "EOF on netlink\n");
 391                         return -1;
 392                 }
 393                 if (msg.msg_namelen != sizeof(nladdr)) {
 394                         fprintf(stderr, "Sender address length == %d\n", msg.msg_namelen);
 395                         exit(1);
 396                 }
 397                 for (h = (struct nlmsghdr*)buf; (unsigned)status >= sizeof(*h); ) {
 398                         int err;
 399                         int len = h->nlmsg_len;
 400                         int l = len - sizeof(*h);
 401
 402                         if (l<0 || len>status) {
 403                                 if (msg.msg_flags & MSG_TRUNC) {
 404                                         fprintf(stderr, "Truncated message\n");
 405                                         return -1;
 406                                 }
 407                                 fprintf(stderr, "!!!malformed message: len=%d\n", len);
 408                                 exit(1);
 409                         }
 410
 411                         err = handler(&nladdr, h, jarg);
 412                         if (err < 0)
 413                                 return err;
 414
 415                         status -= NLMSG_ALIGN(len);
 416                         h = (struct nlmsghdr*)((char*)h + NLMSG_ALIGN(len));
 417                 }
 418                 if (msg.msg_flags & MSG_TRUNC) {
 419                         fprintf(stderr, "Message truncated\n");
 420                         continue;
 421                 }
 422                 if (status) {
 423                         fprintf(stderr, "!!!Remnant of size %d\n", status);
 424                         exit(1);
 425                 }
 426         }
 427 }
 428
 429 int rtnl_from_file(FILE *rtnl, rtnl_filter_t handler,
 430                    void *jarg)
 431 {
 432         int status;
 433         struct sockaddr_nl nladdr;
 434         char   buf[8192];
 435         struct nlmsghdr *h = (void*)buf;
 436
 437         memset(&nladdr, 0, sizeof(nladdr));
 438         nladdr.nl_family = AF_NETLINK;
 439         nladdr.nl_pid = 0;
 440         nladdr.nl_groups = 0;
 441
 442         while (1) {
 443                 int err, len;
 444                 int l;
 445
 446                 status = fread(&buf, 1, sizeof(*h), rtnl);
 447
 448                 if (status < 0) {
 449                         if (errno == EINTR)
 450                                 continue;
 451                         perror("rtnl_from_file: fread");
 452                         return -1;
 453                 }
 454                 if (status == 0)
 455                         return 0;
 456
 457                 len = h->nlmsg_len;
 458                 l = len - sizeof(*h);
 459
 460                 if (l<0 || (unsigned)len>sizeof(buf)) {
 461                         fprintf(stderr, "!!!malformed message: len=%d @%lu\n",
 462                                 len, ftell(rtnl));
 463                         return -1;
 464                 }
 465
 466                 status = fread(NLMSG_DATA(h), 1, NLMSG_ALIGN(l), rtnl);
 467
 468                 if (status < 0) {
 469                         perror("rtnl_from_file: fread");
 470                         return -1;
 471                 }
 472                 if (status < l) {
 473                         fprintf(stderr, "rtnl-from_file: truncated message\n");
 474                         return -1;
 475                 }
 476
 477                 err = handler(&nladdr, h, jarg);
 478                 if (err < 0)
 479                         return err;
 480         }
 481 }
 482
 483 int addattr32(struct nlmsghdr *n, int maxlen, int type, __u32 data)
 484 {
 485         int len = RTA_LENGTH(4);
 486         struct rtattr *rta;
 487         if ((int)NLMSG_ALIGN(n->nlmsg_len) + len > maxlen) {
 488                 fprintf(stderr,"addattr32: Error! max allowed bound %d exceeded\n",maxlen);
 489                 return -1;
 490         }
 491         rta = NLMSG_TAIL(n);
 492         rta->rta_type = type;
 493         rta->rta_len = len;
 494         memcpy(RTA_DATA(rta), &data, 4);
 495         n->nlmsg_len = NLMSG_ALIGN(n->nlmsg_len) + len;
 496         return 0;
 497 }
 498
 499 int addattr_l(struct nlmsghdr *n, int maxlen, int type, const void *data,
 500               int alen)
 501 {
 502         int len = RTA_LENGTH(alen);
 503         struct rtattr *rta;
 504
 505         if ((int)NLMSG_ALIGN(n->nlmsg_len) + RTA_ALIGN(len) > maxlen) {
 506                 fprintf(stderr, "addattr_l ERROR: message exceeded bound of %d\n",maxlen);
 507                 return -1;
 508         }
 509         rta = NLMSG_TAIL(n);
 510         rta->rta_type = type;
 511         rta->rta_len = len;
 512         memcpy(RTA_DATA(rta), data, alen);
 513         n->nlmsg_len = NLMSG_ALIGN(n->nlmsg_len) + RTA_ALIGN(len);
 514         return 0;
 515 }
 516
 517 int addraw_l(struct nlmsghdr *n, int maxlen, const void *data, int len)
 518 {
 519         if ((int)NLMSG_ALIGN(n->nlmsg_len) + (int)NLMSG_ALIGN(len) > maxlen) {
 520                 fprintf(stderr, "addraw_l ERROR: message exceeded bound of %d\n",maxlen);
 521                 return -1;
 522         }
 523
 524         memcpy(NLMSG_TAIL(n), data, len);
 525         memset((void *) NLMSG_TAIL(n) + len, 0, NLMSG_ALIGN(len) - len);
 526         n->nlmsg_len = NLMSG_ALIGN(n->nlmsg_len) + NLMSG_ALIGN(len);
 527         return 0;
 528 }
 529
 530 int rta_addattr32(struct rtattr *rta, int maxlen, int type, __u32 data)
 531 {
 532         int len = RTA_LENGTH(4);
 533         struct rtattr *subrta;
 534
 535         if (RTA_ALIGN(rta->rta_len) + len > maxlen) {
 536                 fprintf(stderr,"rta_addattr32: Error! max allowed bound %d exceeded\n",maxlen);
 537                 return -1;
 538         }
 539         subrta = (struct rtattr*)(((char*)rta) + RTA_ALIGN(rta->rta_len));
 540         subrta->rta_type = type;
 541         subrta->rta_len = len;
 542         memcpy(RTA_DATA(subrta), &data, 4);
 543         rta->rta_len = NLMSG_ALIGN(rta->rta_len) + len;
 544         return 0;
 545 }
 546
 547 int rta_addattr_l(struct rtattr *rta, int maxlen, int type,
 548                   const void *data, int alen)
 549 {
 550         struct rtattr *subrta;
 551         int len = RTA_LENGTH(alen);
 552
 553         if (RTA_ALIGN(rta->rta_len) + RTA_ALIGN(len) > maxlen) {
 554                 fprintf(stderr,"rta_addattr_l: Error! max allowed bound %d exceeded\n",maxlen);
 555                 return -1;
 556         }
 557         subrta = (struct rtattr*)(((char*)rta) + RTA_ALIGN(rta->rta_len));
 558         subrta->rta_type = type;
 559         subrta->rta_len = len;
 560         memcpy(RTA_DATA(subrta), data, alen);
 561         rta->rta_len = NLMSG_ALIGN(rta->rta_len) + RTA_ALIGN(len);
 562         return 0;
 563 }
 564
 565 int parse_rtattr(struct rtattr *tb[], int max, struct rtattr *rta, int len)
 566 {
 567         memset(tb, 0, sizeof(struct rtattr *) * (max + 1));
 568         while (RTA_OK(rta, len)) {
 569                 if (rta->rta_type <= max)
 570                         tb[rta->rta_type] = rta;
 571                 rta = RTA_NEXT(rta,len);
 572         }
 573         if (len)
 574                 fprintf(stderr, "!!!Deficit %d, rta_len=%d\n", len, rta->rta_len);
 575         return 0;
 576 }
 577
 578 int parse_rtattr_byindex(struct rtattr *tb[], int max, struct rtattr *rta, int len)
 579 {
 580         int i = 0;
 581
 582         memset(tb, 0, sizeof(struct rtattr *) * max);
 583         while (RTA_OK(rta, len)) {
 584                 if (rta->rta_type <= max && i < max)
 585                         tb[i++] = rta;
 586                 rta = RTA_NEXT(rta,len);
 587         }
 588         if (len)
 589                 fprintf(stderr, "!!!Deficit %d, rta_len=%d\n", len, rta->rta_len);
 590         return i;
 591 }