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