zebra/zebra_fpm_netlink.c

   1 /*
   2  * Code for encoding/decoding FPM messages that are in netlink format.
   3  *
   4  * Copyright (C) 1997, 98, 99 Kunihiro Ishiguro
   5  * Copyright (C) 2012 by Open Source Routing.
   6  * Copyright (C) 2012 by Internet Systems Consortium, Inc. ("ISC")
   7  *
   8  * This file is part of GNU Zebra.
   9  *
  10  * GNU Zebra is free software; you can redistribute it and/or modify it
  11  * under the terms of the GNU General Public License as published by the
  12  * Free Software Foundation; either version 2, or (at your option) any
  13  * later version.
  14  *
  15  * GNU Zebra is distributed in the hope that it will be useful, but
  16  * WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  18  * General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU General Public License
  21  * along with GNU Zebra; see the file COPYING.  If not, write to the Free
  22  * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
  23  * 02111-1307, USA.
  24  */
  25
  26 #include <zebra.h>
  27
  28 #include "log.h"
  29 #include "rib.h"
  30 #include "vty.h"
  31
  32 #include "zebra/zserv.h"
  33 #include "zebra/zebra_ns.h"
  34 #include "zebra/zebra_vrf.h"
  35 #include "zebra/kernel_netlink.h"
  36 #include "zebra/rt_netlink.h"
  37 #include "nexthop.h"
  38
  39 #include "zebra/zebra_fpm_private.h"
  40
  41 /*
  42  * addr_to_a
  43  *
  44  * Returns string representation of an address of the given AF.
  45  */
  46 static inline const char *
  47 addr_to_a (u_char af, void *addr)
  48 {
  49   if (!addr)
  50     return "<No address>";
  51
  52   switch (af)
  53     {
  54
  55     case AF_INET:
  56       return inet_ntoa (*((struct in_addr *) addr));
  57       break;
  58     case AF_INET6:
  59       return inet6_ntoa (*((struct in6_addr *) addr));
  60       break;
  61     default:
  62       return "<Addr in unknown AF>";
  63       break;
  64     }
  65 }
  66
  67 /*
  68  * prefix_addr_to_a
  69  *
  70  * Convience wrapper that returns a human-readable string for the
  71  * address in a prefix.
  72  */
  73 static const char *
  74 prefix_addr_to_a (struct prefix *prefix)
  75 {
  76   if (!prefix)
  77     return "<No address>";
  78
  79   return addr_to_a (prefix->family, &prefix->u.prefix);
  80 }
  81
  82 /*
  83  * af_addr_size
  84  *
  85  * The size of an address in a given address family.
  86  */
  87 static size_t
  88 af_addr_size (u_char af)
  89 {
  90   switch (af)
  91     {
  92
  93     case AF_INET:
  94       return 4;
  95       break;
  96     case AF_INET6:
  97       return 16;
  98       break;
  99     default:
 100       assert(0);
 101       return 16;
 102     }
 103 }
 104
 105 /*
 106  * netlink_nh_info_t
 107  *
 108  * Holds information about a single nexthop for netlink. These info
 109  * structures are transient and may contain pointers into rib
 110  * data structures for convenience.
 111  */
 112 typedef struct netlink_nh_info_t_
 113 {
 114   uint32_t if_index;
 115   union g_addr *gateway;
 116
 117   /*
 118    * Information from the struct nexthop from which this nh was
 119    * derived. For debug purposes only.
 120    */
 121   int recursive;
 122   enum nexthop_types_t type;
 123 } netlink_nh_info_t;
 124
 125 /*
 126  * netlink_route_info_t
 127  *
 128  * A structure for holding information for a netlink route message.
 129  */
 130 typedef struct netlink_route_info_t_
 131 {
 132   uint16_t nlmsg_type;
 133   u_char rtm_type;
 134   uint32_t rtm_table;
 135   u_char rtm_protocol;
 136   u_char af;
 137   struct prefix *prefix;
 138   uint32_t *metric;
 139   int num_nhs;
 140
 141   /*
 142    * Nexthop structures
 143    */
 144   netlink_nh_info_t nhs[MULTIPATH_NUM];
 145   union g_addr *pref_src;
 146 } netlink_route_info_t;
 147
 148 /*
 149  * netlink_route_info_add_nh
 150  *
 151  * Add information about the given nexthop to the given route info
 152  * structure.
 153  *
 154  * Returns TRUE if a nexthop was added, FALSE otherwise.
 155  */
 156 static int
 157 netlink_route_info_add_nh (netlink_route_info_t *ri, struct nexthop *nexthop,
 158                            int recursive)
 159 {
 160   netlink_nh_info_t nhi;
 161   union g_addr *src;
 162
 163   memset (&nhi, 0, sizeof (nhi));
 164   src = NULL;
 165
 166   if (ri->num_nhs >= (int) ZEBRA_NUM_OF (ri->nhs))
 167     return 0;
 168
 169   nhi.recursive = recursive;
 170   nhi.type = nexthop->type;
 171   nhi.if_index = nexthop->ifindex;
 172
 173   if (nexthop->type == NEXTHOP_TYPE_IPV4
 174       || nexthop->type == NEXTHOP_TYPE_IPV4_IFINDEX)
 175     {
 176       nhi.gateway = &nexthop->gate;
 177       if (nexthop->src.ipv4.s_addr)
 178         src = &nexthop->src;
 179     }
 180
 181   if (nexthop->type == NEXTHOP_TYPE_IPV6
 182       || nexthop->type == NEXTHOP_TYPE_IPV6_IFINDEX)
 183     {
 184       nhi.gateway = &nexthop->gate;
 185     }
 186
 187   if (nexthop->type == NEXTHOP_TYPE_IFINDEX)
 188     {
 189       if (nexthop->src.ipv4.s_addr)
 190         src = &nexthop->src;
 191     }
 192
 193   if (!nhi.gateway && nhi.if_index == 0)
 194     return 0;
 195
 196   /*
 197    * We have a valid nhi. Copy the structure over to the route_info.
 198    */
 199   ri->nhs[ri->num_nhs] = nhi;
 200   ri->num_nhs++;
 201
 202   if (src && !ri->pref_src)
 203     ri->pref_src = src;
 204
 205   return 1;
 206 }
 207
 208 /*
 209  * netlink_proto_from_route_type
 210  */
 211 static u_char
 212 netlink_proto_from_route_type (int type)
 213 {
 214   switch (type)
 215     {
 216     case ZEBRA_ROUTE_KERNEL:
 217     case ZEBRA_ROUTE_CONNECT:
 218       return RTPROT_KERNEL;
 219
 220     default:
 221       return RTPROT_ZEBRA;
 222     }
 223 }
 224
 225 /*
 226  * netlink_route_info_fill
 227  *
 228  * Fill out the route information object from the given route.
 229  *
 230  * Returns TRUE on success and FALSE on failure.
 231  */
 232 static int
 233 netlink_route_info_fill (netlink_route_info_t *ri, int cmd,
 234                          rib_dest_t *dest, struct rib *rib)
 235 {
 236   struct nexthop *nexthop, *tnexthop;
 237   int recursing;
 238   int discard;
 239
 240   memset (ri, 0, sizeof (*ri));
 241
 242   ri->prefix = rib_dest_prefix (dest);
 243   ri->af = rib_dest_af (dest);
 244
 245   ri->nlmsg_type = cmd;
 246   ri->rtm_table = zvrf_id (rib_dest_vrf (dest));
 247   ri->rtm_protocol = RTPROT_UNSPEC;
 248
 249   /*
 250    * An RTM_DELROUTE need not be accompanied by any nexthops,
 251    * particularly in our communication with the FPM.
 252    */
 253   if (cmd == RTM_DELROUTE && !rib)
 254     goto skip;
 255
 256   if (rib)
 257     ri->rtm_protocol = netlink_proto_from_route_type (rib->type);
 258
 259   if ((rib->flags & ZEBRA_FLAG_BLACKHOLE) || (rib->flags & ZEBRA_FLAG_REJECT))
 260     discard = 1;
 261   else
 262     discard = 0;
 263
 264   if (cmd == RTM_NEWROUTE)
 265     {
 266       if (discard)
 267         {
 268           if (rib->flags & ZEBRA_FLAG_BLACKHOLE)
 269             ri->rtm_type = RTN_BLACKHOLE;
 270           else if (rib->flags & ZEBRA_FLAG_REJECT)
 271             ri->rtm_type = RTN_UNREACHABLE;
 272           else
 273             assert (0);
 274         }
 275       else
 276         ri->rtm_type = RTN_UNICAST;
 277     }
 278
 279   ri->metric = &rib->metric;
 280
 281   if (discard)
 282     {
 283       goto skip;
 284     }
 285
 286   for (ALL_NEXTHOPS_RO(rib->nexthop, nexthop, tnexthop, recursing))
 287     {
 288       if (ri->num_nhs >= MULTIPATH_NUM)
 289         break;
 290
 291       if (CHECK_FLAG(nexthop->flags, NEXTHOP_FLAG_RECURSIVE))
 292         continue;
 293
 294       if ((cmd == RTM_NEWROUTE
 295            && CHECK_FLAG (nexthop->flags, NEXTHOP_FLAG_ACTIVE))
 296           || (cmd == RTM_DELROUTE
 297               && CHECK_FLAG (nexthop->flags, NEXTHOP_FLAG_FIB)))
 298         {
 299           netlink_route_info_add_nh (ri, nexthop, recursing);
 300         }
 301     }
 302
 303   /* If there is no useful nexthop then return. */
 304   if (ri->num_nhs == 0)
 305     {
 306       zfpm_debug ("netlink_encode_route(): No useful nexthop.");
 307       return 0;
 308     }
 309
 310  skip:
 311   return 1;
 312 }
 313
 314 /*
 315  * netlink_route_info_encode
 316  *
 317  * Returns the number of bytes written to the buffer. 0 or a negative
 318  * value indicates an error.
 319  */
 320 static int
 321 netlink_route_info_encode (netlink_route_info_t *ri, char *in_buf,
 322                            size_t in_buf_len)
 323 {
 324   size_t bytelen;
 325   int nexthop_num = 0;
 326   size_t buf_offset;
 327   netlink_nh_info_t *nhi;
 328
 329   struct
 330   {
 331     struct nlmsghdr n;
 332     struct rtmsg r;
 333     char buf[1];
 334   } *req;
 335
 336   req = (void *) in_buf;
 337
 338   buf_offset = ((char *) req->buf) - ((char *) req);
 339
 340   if (in_buf_len < buf_offset) {
 341     assert(0);
 342     return 0;
 343   }
 344
 345   memset (req, 0, buf_offset);
 346
 347   bytelen = af_addr_size (ri->af);
 348
 349   req->n.nlmsg_len = NLMSG_LENGTH (sizeof (struct rtmsg));
 350   req->n.nlmsg_flags = NLM_F_CREATE | NLM_F_REQUEST;
 351   req->n.nlmsg_type = ri->nlmsg_type;
 352   req->r.rtm_family = ri->af;
 353   req->r.rtm_table = ri->rtm_table;
 354   req->r.rtm_dst_len = ri->prefix->prefixlen;
 355   req->r.rtm_protocol = ri->rtm_protocol;
 356   req->r.rtm_scope = RT_SCOPE_UNIVERSE;
 357
 358   addattr_l (&req->n, in_buf_len, RTA_DST, &ri->prefix->u.prefix, bytelen);
 359
 360   req->r.rtm_type = ri->rtm_type;
 361
 362   /* Metric. */
 363   if (ri->metric)
 364     addattr32 (&req->n, in_buf_len, RTA_PRIORITY, *ri->metric);
 365
 366   if (ri->num_nhs == 0)
 367     goto done;
 368
 369   if (ri->num_nhs == 1)
 370     {
 371       nhi = &ri->nhs[0];
 372
 373       if (nhi->gateway)
 374         {
 375           addattr_l (&req->n, in_buf_len, RTA_GATEWAY, nhi->gateway,
 376                      bytelen);
 377         }
 378
 379       if (nhi->if_index)
 380         {
 381           addattr32 (&req->n, in_buf_len, RTA_OIF, nhi->if_index);
 382         }
 383
 384       goto done;
 385
 386     }
 387
 388   /*
 389    * Multipath case.
 390    */
 391   char buf[NL_PKT_BUF_SIZE];
 392   struct rtattr *rta = (void *) buf;
 393   struct rtnexthop *rtnh;
 394
 395   rta->rta_type = RTA_MULTIPATH;
 396   rta->rta_len = RTA_LENGTH (0);
 397   rtnh = RTA_DATA (rta);
 398
 399   for (nexthop_num = 0; nexthop_num < ri->num_nhs; nexthop_num++)
 400     {
 401       nhi = &ri->nhs[nexthop_num];
 402
 403       rtnh->rtnh_len = sizeof (*rtnh);
 404       rtnh->rtnh_flags = 0;
 405       rtnh->rtnh_hops = 0;
 406       rtnh->rtnh_ifindex = 0;
 407       rta->rta_len += rtnh->rtnh_len;
 408
 409       if (nhi->gateway)
 410         {
 411           rta_addattr_l (rta, sizeof (buf), RTA_GATEWAY, nhi->gateway, bytelen);
 412           rtnh->rtnh_len += sizeof (struct rtattr) + bytelen;
 413         }
 414
 415       if (nhi->if_index)
 416         {
 417           rtnh->rtnh_ifindex = nhi->if_index;
 418         }
 419
 420       rtnh = RTNH_NEXT (rtnh);
 421     }
 422
 423   assert (rta->rta_len > RTA_LENGTH (0));
 424   addattr_l (&req->n, in_buf_len, RTA_MULTIPATH, RTA_DATA (rta),
 425              RTA_PAYLOAD (rta));
 426
 427 done:
 428
 429   if (ri->pref_src)
 430     {
 431       addattr_l (&req->n, in_buf_len, RTA_PREFSRC, &ri->pref_src, bytelen);
 432     }
 433
 434   assert (req->n.nlmsg_len < in_buf_len);
 435   return req->n.nlmsg_len;
 436 }
 437
 438 /*
 439  * zfpm_log_route_info
 440  *
 441  * Helper function to log the information in a route_info structure.
 442  */
 443 static void
 444 zfpm_log_route_info (netlink_route_info_t *ri, const char *label)
 445 {
 446   netlink_nh_info_t *nhi;
 447   int i;
 448
 449   zfpm_debug ("%s : %s %s/%d, Proto: %s, Metric: %u", label,
 450               nl_msg_type_to_str (ri->nlmsg_type),
 451               prefix_addr_to_a (ri->prefix), ri->prefix->prefixlen,
 452               nl_rtproto_to_str (ri->rtm_protocol),
 453               ri->metric ? *ri->metric : 0);
 454
 455   for (i = 0; i < ri->num_nhs; i++)
 456     {
 457       nhi = &ri->nhs[i];
 458       zfpm_debug("  Intf: %u, Gateway: %s, Recursive: %s, Type: %s",
 459                  nhi->if_index, addr_to_a (ri->af, nhi->gateway),
 460                  nhi->recursive ? "yes" : "no",
 461                  nexthop_type_to_str (nhi->type));
 462     }
 463 }
 464
 465 /*
 466  * zfpm_netlink_encode_route
 467  *
 468  * Create a netlink message corresponding to the given route in the
 469  * given buffer space.
 470  *
 471  * Returns the number of bytes written to the buffer. 0 or a negative
 472  * value indicates an error.
 473  */
 474 int
 475 zfpm_netlink_encode_route (int cmd, rib_dest_t *dest, struct rib *rib,
 476                            char *in_buf, size_t in_buf_len)
 477 {
 478   netlink_route_info_t ri_space, *ri;
 479
 480   ri = &ri_space;
 481
 482   if (!netlink_route_info_fill (ri, cmd, dest, rib))
 483     return 0;
 484
 485   zfpm_log_route_info (ri, __FUNCTION__);
 486
 487   return netlink_route_info_encode (ri, in_buf, in_buf_len);
 488 }