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,
  34                       int protocol)
  35 {
  36         socklen_t addr_len;
  37         int sndbuf = 32768;
  38         int rcvbuf = 32768;
  39
  40         memset(rth, 0, sizeof(rth));
  41
  42         rth->fd = socket(AF_NETLINK, SOCK_RAW, protocol);
  43         if (rth->fd < 0) {
  44                 perror("Cannot open netlink socket");
  45                 return -1;
  46         }
  47
  48         if (setsockopt(rth->fd,SOL_SOCKET,SO_SNDBUF,&sndbuf,sizeof(sndbuf)) < 0) {
  49                 perror("SO_SNDBUF");
  50                 return -1;
  51         }
  52
  53         if (setsockopt(rth->fd,SOL_SOCKET,SO_RCVBUF,&rcvbuf,sizeof(rcvbuf)) < 0) {
  54                 perror("SO_RCVBUF");
  55                 return -1;
  56         }
  57
  58         memset(&rth->local, 0, sizeof(rth->local));
  59         rth->local.nl_family = AF_NETLINK;
  60         rth->local.nl_groups = subscriptions;
  61
  62         if (bind(rth->fd, (struct sockaddr*)&rth->local, sizeof(rth->local)) < 0) {
  63                 perror("Cannot bind netlink socket");
  64                 return -1;
  65         }
  66         addr_len = sizeof(rth->local);
  67         if (getsockname(rth->fd, (struct sockaddr*)&rth->local, &addr_len) < 0) {
  68                 perror("Cannot getsockname");
  69                 return -1;
  70         }
  71         if (addr_len != sizeof(rth->local)) {
  72                 fprintf(stderr, "Wrong address length %d\n", addr_len);
  73                 return -1;
  74         }
  75         if (rth->local.nl_family != AF_NETLINK) {
  76                 fprintf(stderr, "Wrong address family %d\n", rth->local.nl_family);
  77                 return -1;
  78         }
  79         rth->seq = time(NULL);
  80         return 0;
  81 }
  82
  83 int rtnl_open(struct rtnl_handle *rth, unsigned subscriptions)
  84 {
  85         return rtnl_open_byproto(rth, subscriptions, NETLINK_ROUTE);
  86 }
  87
  88 int rtnl_wilddump_request(struct rtnl_handle *rth, int family, int type)
  89 {
  90         struct {
  91                 struct nlmsghdr nlh;
  92                 struct rtgenmsg g;
  93         } req;
  94         struct sockaddr_nl nladdr;
  95
  96         memset(&nladdr, 0, sizeof(nladdr));
  97         nladdr.nl_family = AF_NETLINK;
  98
  99         memset(&req, 0, sizeof(req));
 100         req.nlh.nlmsg_len = sizeof(req);
 101         req.nlh.nlmsg_type = type;
 102         req.nlh.nlmsg_flags = NLM_F_ROOT|NLM_F_MATCH|NLM_F_REQUEST;
 103         req.nlh.nlmsg_pid = 0;
 104         req.nlh.nlmsg_seq = rth->dump = ++rth->seq;
 105         req.g.rtgen_family = family;
 106
 107         return sendto(rth->fd, (void*)&req, sizeof(req), 0,
 108                       (struct sockaddr*)&nladdr, sizeof(nladdr));
 109 }
 110
 111 int rtnl_send(struct rtnl_handle *rth, const char *buf, int len)
 112 {
 113         struct sockaddr_nl nladdr;
 114
 115         memset(&nladdr, 0, sizeof(nladdr));
 116         nladdr.nl_family = AF_NETLINK;
 117
 118         return sendto(rth->fd, buf, len, 0, (struct sockaddr*)&nladdr, sizeof(nladdr));
 119 }
 120
 121 int rtnl_dump_request(struct rtnl_handle *rth, int type, void *req, int len)
 122 {
 123         struct nlmsghdr nlh;
 124         struct sockaddr_nl nladdr;
 125         struct iovec iov[2] = {
 126                 { .iov_base = &nlh, .iov_len = sizeof(nlh) },
 127                 { .iov_base = req, .iov_len = len }
 128         };
 129         struct msghdr msg = {
 130                 .msg_name = &nladdr,
 131                 .msg_namelen =  sizeof(nladdr),
 132                 .msg_iov = iov,
 133                 .msg_iovlen = 2,
 134         };
 135
 136         memset(&nladdr, 0, sizeof(nladdr));
 137         nladdr.nl_family = AF_NETLINK;
 138
 139         nlh.nlmsg_len = NLMSG_LENGTH(len);
 140         nlh.nlmsg_type = type;
 141         nlh.nlmsg_flags = NLM_F_ROOT|NLM_F_MATCH|NLM_F_REQUEST;
 142         nlh.nlmsg_pid = 0;
 143         nlh.nlmsg_seq = rth->dump = ++rth->seq;
 144
 145         return sendmsg(rth->fd, &msg, 0);
 146 }
 147
 148 int rtnl_dump_filter(struct rtnl_handle *rth,
 149                      rtnl_filter_t filter,
 150                      void *arg1,
 151                      rtnl_filter_t junk,
 152                      void *arg2)
 153 {
 154         struct sockaddr_nl nladdr;
 155         struct iovec iov;
 156         struct msghdr msg = {
 157                 .msg_name = &nladdr,
 158                 .msg_namelen = sizeof(nladdr),
 159                 .msg_iov = &iov,
 160                 .msg_iovlen = 1,
 161         };
 162         char buf[16384];
 163
 164         iov.iov_base = buf;
 165         while (1) {
 166                 int status;
 167                 struct nlmsghdr *h;
 168
 169                 iov.iov_len = sizeof(buf);
 170                 status = recvmsg(rth->fd, &msg, 0);
 171
 172                 if (status < 0) {
 173                         if (errno == EINTR)
 174                                 continue;
 175                         perror("OVERRUN");
 176                         continue;
 177                 }
 178
 179                 if (status == 0) {
 180                         fprintf(stderr, "EOF on netlink\n");
 181                         return -1;
 182                 }
 183
 184                 h = (struct nlmsghdr*)buf;
 185                 while (NLMSG_OK(h, status)) {
 186                         int err;
 187
 188                         if (nladdr.nl_pid != 0 ||
 189                             h->nlmsg_pid != rth->local.nl_pid ||
 190                             h->nlmsg_seq != rth->dump) {
 191                                 if (junk) {
 192                                         err = junk(&nladdr, h, arg2);
 193                                         if (err < 0)
 194                                                 return err;
 195                                 }
 196                                 goto skip_it;
 197                         }
 198
 199                         if (h->nlmsg_type == NLMSG_DONE)
 200                                 return 0;
 201                         if (h->nlmsg_type == NLMSG_ERROR) {
 202                                 struct nlmsgerr *err = (struct nlmsgerr*)NLMSG_DATA(h);
 203                                 if (h->nlmsg_len < NLMSG_LENGTH(sizeof(struct nlmsgerr))) {
 204                                         fprintf(stderr, "ERROR truncated\n");
 205                                 } else {
 206                                         errno = -err->error;
 207                                         perror("RTNETLINK answers");
 208                                 }
 209                                 return -1;
 210                         }
 211                         err = filter(&nladdr, h, arg1);
 212                         if (err < 0)
 213                                 return err;
 214
 215 skip_it:
 216                         h = NLMSG_NEXT(h, status);
 217                 }
 218                 if (msg.msg_flags & MSG_TRUNC) {
 219                         fprintf(stderr, "Message truncated\n");
 220                         continue;
 221                 }
 222                 if (status) {
 223                         fprintf(stderr, "!!!Remnant of size %d\n", status);
 224                         exit(1);
 225                 }
 226         }
 227 }
 228
 229 int rtnl_talk(struct rtnl_handle *rtnl, struct nlmsghdr *n, pid_t peer,
 230               unsigned groups, struct nlmsghdr *answer,
 231               rtnl_filter_t junk,
 232               void *jarg)
 233 {
 234         int status;
 235         unsigned seq;
 236         struct nlmsghdr *h;
 237         struct sockaddr_nl nladdr;
 238         struct iovec iov = {
 239                 .iov_base = (void*) n,
 240                 .iov_len = n->nlmsg_len
 241         };
 242         struct msghdr msg = {
 243                 .msg_name = &nladdr,
 244                 .msg_namelen = sizeof(nladdr),
 245                 .msg_iov = &iov,
 246                 .msg_iovlen = 1,
 247         };
 248         char   buf[16384];
 249
 250         memset(&nladdr, 0, sizeof(nladdr));
 251         nladdr.nl_family = AF_NETLINK;
 252         nladdr.nl_pid = peer;
 253         nladdr.nl_groups = groups;
 254
 255         n->nlmsg_seq = seq = ++rtnl->seq;
 256
 257         if (answer == NULL)
 258                 n->nlmsg_flags |= NLM_F_ACK;
 259
 260         status = sendmsg(rtnl->fd, &msg, 0);
 261
 262         if (status < 0) {
 263                 perror("Cannot talk to rtnetlink");
 264                 return -1;
 265         }
 266
 267         memset(buf,0,sizeof(buf));
 268
 269         iov.iov_base = buf;
 270
 271         while (1) {
 272                 iov.iov_len = sizeof(buf);
 273                 status = recvmsg(rtnl->fd, &msg, 0);
 274
 275                 if (status < 0) {
 276                         if (errno == EINTR)
 277                                 continue;
 278                         perror("OVERRUN");
 279                         continue;
 280                 }
 281                 if (status == 0) {
 282                         fprintf(stderr, "EOF on netlink\n");
 283                         return -1;
 284                 }
 285                 if (msg.msg_namelen != sizeof(nladdr)) {
 286                         fprintf(stderr, "sender address length == %d\n", msg.msg_namelen);
 287                         exit(1);
 288                 }
 289                 for (h = (struct nlmsghdr*)buf; status >= sizeof(*h); ) {
 290                         int err;
 291                         int len = h->nlmsg_len;
 292                         int l = len - sizeof(*h);
 293
 294                         if (l<0 || len>status) {
 295                                 if (msg.msg_flags & MSG_TRUNC) {
 296                                         fprintf(stderr, "Truncated message\n");
 297                                         return -1;
 298                                 }
 299                                 fprintf(stderr, "!!!malformed message: len=%d\n", len);
 300                                 exit(1);
 301                         }
 302
 303                         if (nladdr.nl_pid != peer ||
 304                             h->nlmsg_pid != rtnl->local.nl_pid ||
 305                             h->nlmsg_seq != seq) {
 306                                 if (junk) {
 307                                         err = junk(&nladdr, h, jarg);
 308                                         if (err < 0)
 309                                                 return err;
 310                                 }
 311                                 /* Don't forget to skip that message. */
 312                                 status -= NLMSG_ALIGN(len);
 313                                 h = (struct nlmsghdr*)((char*)h + NLMSG_ALIGN(len));
 314                                 continue;
 315                         }
 316
 317                         if (h->nlmsg_type == NLMSG_ERROR) {
 318                                 struct nlmsgerr *err = (struct nlmsgerr*)NLMSG_DATA(h);
 319                                 if (l < sizeof(struct nlmsgerr)) {
 320                                         fprintf(stderr, "ERROR truncated\n");
 321                                 } else {
 322                                         errno = -err->error;
 323                                         if (errno == 0) {
 324                                                 if (answer)
 325                                                         memcpy(answer, h, h->nlmsg_len);
 326                                                 return 0;
 327                                         }
 328                                         perror("RTNETLINK answers");
 329                                 }
 330                                 return -1;
 331                         }
 332                         if (answer) {
 333                                 memcpy(answer, h, h->nlmsg_len);
 334                                 return 0;
 335                         }
 336
 337                         fprintf(stderr, "Unexpected reply!!!\n");
 338
 339                         status -= NLMSG_ALIGN(len);
 340                         h = (struct nlmsghdr*)((char*)h + NLMSG_ALIGN(len));
 341                 }
 342                 if (msg.msg_flags & MSG_TRUNC) {
 343                         fprintf(stderr, "Message truncated\n");
 344                         continue;
 345                 }
 346                 if (status) {
 347                         fprintf(stderr, "!!!Remnant of size %d\n", status);
 348                         exit(1);
 349                 }
 350         }
 351 }
 352
 353 int rtnl_listen(struct rtnl_handle *rtnl,
 354                 rtnl_filter_t handler,
 355                 void *jarg)
 356 {
 357         int status;
 358         struct nlmsghdr *h;
 359         struct sockaddr_nl nladdr;
 360         struct iovec iov;
 361         struct msghdr msg = {
 362                 .msg_name = &nladdr,
 363                 .msg_namelen = sizeof(nladdr),
 364                 .msg_iov = &iov,
 365                 .msg_iovlen = 1,
 366         };
 367         char   buf[8192];
 368
 369         memset(&nladdr, 0, sizeof(nladdr));
 370         nladdr.nl_family = AF_NETLINK;
 371         nladdr.nl_pid = 0;
 372         nladdr.nl_groups = 0;
 373
 374         iov.iov_base = buf;
 375         while (1) {
 376                 iov.iov_len = sizeof(buf);
 377                 status = recvmsg(rtnl->fd, &msg, 0);
 378
 379                 if (status < 0) {
 380                         if (errno == EINTR)
 381                                 continue;
 382                         if (errno == EAGAIN)
 383                           return 0;
 384                         perror("OVERRUN");
 385                         return -1;
 386                 }
 387                 if (status == 0) {
 388                         fprintf(stderr, "EOF on netlink\n");
 389                         return -1;
 390                 }
 391                 if (msg.msg_namelen != sizeof(nladdr)) {
 392                         fprintf(stderr, "Sender address length == %d\n", msg.msg_namelen);
 393                         exit(1);
 394                 }
 395                 for (h = (struct nlmsghdr*)buf; status >= sizeof(*h); ) {
 396                         int err;
 397                         int len = h->nlmsg_len;
 398                         int l = len - sizeof(*h);
 399
 400                         if (l<0 || len>status) {
 401                                 if (msg.msg_flags & MSG_TRUNC) {
 402                                         fprintf(stderr, "Truncated message\n");
 403                                         return -1;
 404                                 }
 405                                 fprintf(stderr, "!!!malformed message: len=%d\n", len);
 406                                 exit(1);
 407                         }
 408
 409                         err = handler(&nladdr, h, jarg);
 410                         if (err < 0) {
 411                           fprintf(stderr, "Handler returned %d\n", err);
 412                           return err;
 413                         }
 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, type;
 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                 type= h->nlmsg_type;
 459                 l = len - sizeof(*h);
 460
 461                 if (l<0 || len>sizeof(buf)) {
 462                         fprintf(stderr, "!!!malformed message: len=%d @%lu\n",
 463                                 len, ftell(rtnl));
 464                         return -1;
 465                 }
 466
 467                 status = fread(NLMSG_DATA(h), 1, NLMSG_ALIGN(l), rtnl);
 468
 469                 if (status < 0) {
 470                         perror("rtnl_from_file: fread");
 471                         return -1;
 472                 }
 473                 if (status < l) {
 474                         fprintf(stderr, "rtnl-from_file: truncated message\n");
 475                         return -1;
 476                 }
 477
 478                 err = handler(&nladdr, h, jarg);
 479                 if (err < 0)
 480                         return err;
 481         }
 482 }
 483
 484 int addattr32(struct nlmsghdr *n, int maxlen, int type, __u32 data)
 485 {
 486         int len = RTA_LENGTH(4);
 487         struct rtattr *rta;
 488         if (NLMSG_ALIGN(n->nlmsg_len) + len > maxlen) {
 489                 fprintf(stderr,"addattr32: Error! max allowed bound %d exceeded\n",maxlen);
 490                 return -1;
 491         }
 492         rta = NLMSG_TAIL(n);
 493         rta->rta_type = type;
 494         rta->rta_len = len;
 495         memcpy(RTA_DATA(rta), &data, 4);
 496         n->nlmsg_len = NLMSG_ALIGN(n->nlmsg_len) + len;
 497         return 0;
 498 }
 499
 500 int addattr_l(struct nlmsghdr *n, int maxlen, int type, const void *data,
 501               int alen)
 502 {
 503         int len = RTA_LENGTH(alen);
 504         struct rtattr *rta;
 505
 506         if (NLMSG_ALIGN(n->nlmsg_len) + RTA_ALIGN(len) > maxlen) {
 507                 fprintf(stderr, "addattr_l ERROR: message exceeded bound of %d\n",maxlen);
 508                 return -1;
 509         }
 510         rta = NLMSG_TAIL(n);
 511         rta->rta_type = type;
 512         rta->rta_len = len;
 513         memcpy(RTA_DATA(rta), data, alen);
 514         n->nlmsg_len = NLMSG_ALIGN(n->nlmsg_len) + RTA_ALIGN(len);
 515         return 0;
 516 }
 517
 518 int addraw_l(struct nlmsghdr *n, int maxlen, const void *data, int len)
 519 {
 520         if (NLMSG_ALIGN(n->nlmsg_len) + NLMSG_ALIGN(len) > maxlen) {
 521                 fprintf(stderr, "addraw_l ERROR: message exceeded bound of %d\n",maxlen);
 522                 return -1;
 523         }
 524
 525         memcpy(NLMSG_TAIL(n), data, len);
 526         memset((void *) NLMSG_TAIL(n) + len, 0, NLMSG_ALIGN(len) - len);
 527         n->nlmsg_len = NLMSG_ALIGN(n->nlmsg_len) + NLMSG_ALIGN(len);
 528         return 0;
 529 }
 530
 531 int rta_addattr32(struct rtattr *rta, int maxlen, int type, __u32 data)
 532 {
 533         int len = RTA_LENGTH(4);
 534         struct rtattr *subrta;
 535
 536         if (RTA_ALIGN(rta->rta_len) + len > maxlen) {
 537                 fprintf(stderr,"rta_addattr32: Error! max allowed bound %d exceeded\n",maxlen);
 538                 return -1;
 539         }
 540         subrta = (struct rtattr*)(((char*)rta) + RTA_ALIGN(rta->rta_len));
 541         subrta->rta_type = type;
 542         subrta->rta_len = len;
 543         memcpy(RTA_DATA(subrta), &data, 4);
 544         rta->rta_len = NLMSG_ALIGN(rta->rta_len) + len;
 545         return 0;
 546 }
 547
 548 int rta_addattr_l(struct rtattr *rta, int maxlen, int type,
 549                   const void *data, int alen)
 550 {
 551         struct rtattr *subrta;
 552         int len = RTA_LENGTH(alen);
 553
 554         if (RTA_ALIGN(rta->rta_len) + RTA_ALIGN(len) > maxlen) {
 555                 fprintf(stderr,"rta_addattr_l: Error! max allowed bound %d exceeded\n",maxlen);
 556                 return -1;
 557         }
 558         subrta = (struct rtattr*)(((char*)rta) + RTA_ALIGN(rta->rta_len));
 559         subrta->rta_type = type;
 560         subrta->rta_len = len;
 561         memcpy(RTA_DATA(subrta), data, alen);
 562         rta->rta_len = NLMSG_ALIGN(rta->rta_len) + RTA_ALIGN(len);
 563         return 0;
 564 }
 565
 566 int parse_rtattr(struct rtattr *tb[], int max, struct rtattr *rta, int len)
 567 {
 568         memset(tb, 0, sizeof(struct rtattr *) * (max + 1));
 569         while (RTA_OK(rta, len)) {
 570                 if (rta->rta_type <= max)
 571                         tb[rta->rta_type] = rta;
 572                 rta = RTA_NEXT(rta,len);
 573         }
 574         if (len)
 575                 fprintf(stderr, "!!!Deficit %d, rta_len=%d\n", len, rta->rta_len);
 576         return 0;
 577 }
 578
 579 int parse_rtattr_byindex(struct rtattr *tb[], int max, struct rtattr *rta, int len)
 580 {
 581         int i = 0;
 582
 583         memset(tb, 0, sizeof(struct rtattr *) * max);
 584         while (RTA_OK(rta, len)) {
 585                 if (rta->rta_type <= max && i < max)
 586                         tb[i++] = rta;
 587                 rta = RTA_NEXT(rta,len);
 588         }
 589         if (len)
 590                 fprintf(stderr, "!!!Deficit %d, rta_len=%d\n", len, rta->rta_len);
 591         return i;
 592 }