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
  31 #include "rt_netlink.h"
  32 #include "nexthop.h"
  33
  34 #include "zebra_fpm_private.h"
  35
  36 /*
  37  * addr_to_a
  38  *
  39  * Returns string representation of an address of the given AF.
  40  */
  41 static inline const char *
  42 addr_to_a (u_char af, void *addr)
  43 {
  44   if (!addr)
  45     return "<No address>";
  46
  47   switch (af)
  48     {
  49
  50     case AF_INET:
  51       return inet_ntoa (*((struct in_addr *) addr));
  52
  53 #ifdef HAVE_IPV6
  54     case AF_INET6:
  55       return inet6_ntoa (*((struct in6_addr *) addr));
  56 #endif
  57
  58     default:
  59       return "<Addr in unknown AF>";
  60     }
  61 }
  62
  63 /*
  64  * prefix_addr_to_a
  65  *
  66  * Convience wrapper that returns a human-readable string for the
  67  * address in a prefix.
  68  */
  69 static const char *
  70 prefix_addr_to_a (struct prefix *prefix)
  71 {
  72   if (!prefix)
  73     return "<No address>";
  74
  75   return addr_to_a (prefix->family, &prefix->u.prefix);
  76 }
  77
  78 /*
  79  * af_addr_size
  80  *
  81  * The size of an address in a given address family.
  82  */
  83 static size_t
  84 af_addr_size (u_char af)
  85 {
  86   switch (af)
  87     {
  88
  89     case AF_INET:
  90       return 4;
  91
  92 #ifdef HAVE_IPV6
  93     case AF_INET6:
  94       return 16;
  95 #endif
  96
  97     default:
  98       assert(0);
  99       return 16;
 100     }
 101 }
 102
 103 /*
 104  * netlink_nh_info_t
 105  *
 106  * Holds information about a single nexthop for netlink. These info
 107  * structures are transient and may contain pointers into rib
 108  * data structures for convenience.
 109  */
 110 typedef struct netlink_nh_info_t_
 111 {
 112   uint32_t if_index;
 113   union g_addr *gateway;
 114
 115   /*
 116    * Information from the struct nexthop from which this nh was
 117    * derived. For debug purposes only.
 118    */
 119   int recursive;
 120   enum nexthop_types_t type;
 121 } netlink_nh_info_t;
 122
 123 /*
 124  * netlink_route_info_t
 125  *
 126  * A structure for holding information for a netlink route message.
 127  */
 128 typedef struct netlink_route_info_t_
 129 {
 130   uint16_t nlmsg_type;
 131   u_char rtm_type;
 132   uint32_t rtm_table;
 133   u_char rtm_protocol;
 134   u_char af;
 135   struct prefix *prefix;
 136   uint32_t *metric;
 137   int num_nhs;
 138
 139   /*
 140    * Nexthop structures. We keep things simple for now by enforcing a
 141    * maximum of 64 in case MULTIPATH_NUM is 0;
 142    */
 143   netlink_nh_info_t nhs[MAX (MULTIPATH_NUM, 64)];
 144   union g_addr *pref_src;
 145 } netlink_route_info_t;
 146
 147 /*
 148  * netlink_route_info_add_nh
 149  *
 150  * Add information about the given nexthop to the given route info
 151  * structure.
 152  *
 153  * Returns TRUE if a nexthop was added, FALSE otherwise.
 154  */
 155 static int
 156 netlink_route_info_add_nh (netlink_route_info_t *ri, struct nexthop *nexthop,
 157                            int recursive)
 158 {
 159   netlink_nh_info_t nhi;
 160   union g_addr *src;
 161
 162   memset (&nhi, 0, sizeof (nhi));
 163   src = NULL;
 164
 165   if (ri->num_nhs >= (int) ZEBRA_NUM_OF (ri->nhs))
 166     return 0;
 167
 168   nhi.recursive = recursive;
 169   nhi.type = nexthop->type;
 170   nhi.if_index = nexthop->ifindex;
 171
 172   if (nexthop->type == NEXTHOP_TYPE_IPV4
 173       || nexthop->type == NEXTHOP_TYPE_IPV4_IFINDEX)
 174     {
 175       nhi.gateway = &nexthop->gate;
 176       if (nexthop->src.ipv4.s_addr)
 177         src = &nexthop->src;
 178     }
 179
 180 #ifdef HAVE_IPV6
 181   if (nexthop->type == NEXTHOP_TYPE_IPV6
 182       || nexthop->type == NEXTHOP_TYPE_IPV6_IFNAME
 183       || nexthop->type == NEXTHOP_TYPE_IPV6_IFINDEX)
 184     {
 185       nhi.gateway = &nexthop->gate;
 186     }
 187 #endif /* HAVE_IPV6 */
 188
 189   if (nexthop->type == NEXTHOP_TYPE_IFINDEX
 190       || nexthop->type == NEXTHOP_TYPE_IFNAME)
 191     {
 192       if (nexthop->src.ipv4.s_addr)
 193         src = &nexthop->src;
 194     }
 195
 196   if (!nhi.gateway && nhi.if_index == 0)
 197     return 0;
 198
 199   /*
 200    * We have a valid nhi. Copy the structure over to the route_info.
 201    */
 202   ri->nhs[ri->num_nhs] = nhi;
 203   ri->num_nhs++;
 204
 205   if (src && !ri->pref_src)
 206     ri->pref_src = src;
 207
 208   return 1;
 209 }
 210
 211 /*
 212  * netlink_proto_from_route_type
 213  */
 214 static u_char
 215 netlink_proto_from_route_type (int type)
 216 {
 217   switch (type)
 218     {
 219     case ZEBRA_ROUTE_KERNEL:
 220     case ZEBRA_ROUTE_CONNECT:
 221       return RTPROT_KERNEL;
 222
 223     default:
 224       return RTPROT_ZEBRA;
 225     }
 226 }
 227
 228 /*
 229  * netlink_route_info_fill
 230  *
 231  * Fill out the route information object from the given route.
 232  *
 233  * Returns TRUE on success and FALSE on failure.
 234  */
 235 static int
 236 netlink_route_info_fill (netlink_route_info_t *ri, int cmd,
 237                          rib_dest_t *dest, struct rib *rib)
 238 {
 239   struct nexthop *nexthop, *tnexthop;
 240   int recursing;
 241   int discard;
 242
 243   memset (ri, 0, sizeof (*ri));
 244
 245   ri->prefix = rib_dest_prefix (dest);
 246   ri->af = rib_dest_af (dest);
 247
 248   ri->nlmsg_type = cmd;
 249   ri->rtm_table = rib_dest_vrf (dest)->id;
 250   ri->rtm_protocol = RTPROT_UNSPEC;
 251
 252   /*
 253    * An RTM_DELROUTE need not be accompanied by any nexthops,
 254    * particularly in our communication with the FPM.
 255    */
 256   if (cmd == RTM_DELROUTE && !rib)
 257     goto skip;
 258
 259   if (rib)
 260     ri->rtm_protocol = netlink_proto_from_route_type (rib->type);
 261
 262   if ((rib->flags & ZEBRA_FLAG_BLACKHOLE) || (rib->flags & ZEBRA_FLAG_REJECT))
 263     discard = 1;
 264   else
 265     discard = 0;
 266
 267   if (cmd == RTM_NEWROUTE)
 268     {
 269       if (discard)
 270         {
 271           if (rib->flags & ZEBRA_FLAG_BLACKHOLE)
 272             ri->rtm_type = RTN_BLACKHOLE;
 273           else if (rib->flags & ZEBRA_FLAG_REJECT)
 274             ri->rtm_type = RTN_UNREACHABLE;
 275           else
 276             assert (0);
 277         }
 278       else
 279         ri->rtm_type = RTN_UNICAST;
 280     }
 281
 282   ri->metric = &rib->metric;
 283
 284   if (discard)
 285     {
 286       goto skip;
 287     }
 288
 289   for (ALL_NEXTHOPS_RO(rib->nexthop, nexthop, tnexthop, recursing))
 290     {
 291       if (MULTIPATH_NUM != 0 && ri->num_nhs >= MULTIPATH_NUM)
 292         break;
 293
 294       if (CHECK_FLAG(nexthop->flags, NEXTHOP_FLAG_RECURSIVE))
 295         continue;
 296
 297       if ((cmd == RTM_NEWROUTE
 298            && CHECK_FLAG (nexthop->flags, NEXTHOP_FLAG_ACTIVE))
 299           || (cmd == RTM_DELROUTE
 300               && CHECK_FLAG (nexthop->flags, NEXTHOP_FLAG_FIB)))
 301         {
 302           netlink_route_info_add_nh (ri, nexthop, recursing);
 303         }
 304     }
 305
 306   /* If there is no useful nexthop then return. */
 307   if (ri->num_nhs == 0)
 308     {
 309       zfpm_debug ("netlink_encode_route(): No useful nexthop.");
 310       return 0;
 311     }
 312
 313  skip:
 314   return 1;
 315 }
 316
 317 /*
 318  * netlink_route_info_encode
 319  *
 320  * Returns the number of bytes written to the buffer. 0 or a negative
 321  * value indicates an error.
 322  */
 323 static int
 324 netlink_route_info_encode (netlink_route_info_t *ri, char *in_buf,
 325                            size_t in_buf_len)
 326 {
 327   int bytelen;
 328   int nexthop_num = 0;
 329   size_t buf_offset;
 330   netlink_nh_info_t *nhi;
 331
 332   struct
 333   {
 334     struct nlmsghdr n;
 335     struct rtmsg r;
 336     char buf[1];
 337   } *req;
 338
 339   req = (void *) in_buf;
 340
 341   buf_offset = ((char *) req->buf) - ((char *) req);
 342
 343   if (in_buf_len < buf_offset) {
 344     assert(0);
 345     return 0;
 346   }
 347
 348   memset (req, 0, buf_offset);
 349
 350   bytelen = af_addr_size (ri->af);
 351
 352   req->n.nlmsg_len = NLMSG_LENGTH (sizeof (struct rtmsg));
 353   req->n.nlmsg_flags = NLM_F_CREATE | NLM_F_REQUEST;
 354   req->n.nlmsg_type = ri->nlmsg_type;
 355   req->r.rtm_family = ri->af;
 356   req->r.rtm_table = ri->rtm_table;
 357   req->r.rtm_dst_len = ri->prefix->prefixlen;
 358   req->r.rtm_protocol = ri->rtm_protocol;
 359   req->r.rtm_scope = RT_SCOPE_UNIVERSE;
 360
 361   addattr_l (&req->n, in_buf_len, RTA_DST, &ri->prefix->u.prefix, bytelen);
 362
 363   req->r.rtm_type = ri->rtm_type;
 364
 365   /* Metric. */
 366   if (ri->metric)
 367     addattr32 (&req->n, in_buf_len, RTA_PRIORITY, *ri->metric);
 368
 369   if (ri->num_nhs == 0)
 370     goto done;
 371
 372   if (ri->num_nhs == 1)
 373     {
 374       nhi = &ri->nhs[0];
 375
 376       if (nhi->gateway)
 377         {
 378           addattr_l (&req->n, in_buf_len, RTA_GATEWAY, nhi->gateway,
 379                      bytelen);
 380         }
 381
 382       if (nhi->if_index)
 383         {
 384           addattr32 (&req->n, in_buf_len, RTA_OIF, nhi->if_index);
 385         }
 386
 387       goto done;
 388
 389     }
 390
 391   /*
 392    * Multipath case.
 393    */
 394   char buf[NL_PKT_BUF_SIZE];
 395   struct rtattr *rta = (void *) buf;
 396   struct rtnexthop *rtnh;
 397
 398   rta->rta_type = RTA_MULTIPATH;
 399   rta->rta_len = RTA_LENGTH (0);
 400   rtnh = RTA_DATA (rta);
 401
 402   for (nexthop_num = 0; nexthop_num < ri->num_nhs; nexthop_num++)
 403     {
 404       nhi = &ri->nhs[nexthop_num];
 405
 406       rtnh->rtnh_len = sizeof (*rtnh);
 407       rtnh->rtnh_flags = 0;
 408       rtnh->rtnh_hops = 0;
 409       rtnh->rtnh_ifindex = 0;
 410       rta->rta_len += rtnh->rtnh_len;
 411
 412       if (nhi->gateway)
 413         {
 414           rta_addattr_l (rta, sizeof (buf), RTA_GATEWAY, nhi->gateway, bytelen);
 415           rtnh->rtnh_len += sizeof (struct rtattr) + bytelen;
 416         }
 417
 418       if (nhi->if_index)
 419         {
 420           rtnh->rtnh_ifindex = nhi->if_index;
 421         }
 422
 423       rtnh = RTNH_NEXT (rtnh);
 424     }
 425
 426   assert (rta->rta_len > RTA_LENGTH (0));
 427   addattr_l (&req->n, in_buf_len, RTA_MULTIPATH, RTA_DATA (rta),
 428              RTA_PAYLOAD (rta));
 429
 430 done:
 431
 432   if (ri->pref_src)
 433     {
 434       addattr_l (&req->n, in_buf_len, RTA_PREFSRC, &ri->pref_src, bytelen);
 435     }
 436
 437   assert (req->n.nlmsg_len < in_buf_len);
 438   return req->n.nlmsg_len;
 439 }
 440
 441 /*
 442  * zfpm_log_route_info
 443  *
 444  * Helper function to log the information in a route_info structure.
 445  */
 446 static void
 447 zfpm_log_route_info (netlink_route_info_t *ri, const char *label)
 448 {
 449   netlink_nh_info_t *nhi;
 450   int i;
 451
 452   zfpm_debug ("%s : %s %s/%d, Proto: %s, Metric: %u", label,
 453               nl_msg_type_to_str (ri->nlmsg_type),
 454               prefix_addr_to_a (ri->prefix), ri->prefix->prefixlen,
 455               nl_rtproto_to_str (ri->rtm_protocol),
 456               ri->metric ? *ri->metric : 0);
 457
 458   for (i = 0; i < ri->num_nhs; i++)
 459     {
 460       nhi = &ri->nhs[i];
 461       zfpm_debug("  Intf: %u, Gateway: %s, Recursive: %s, Type: %s",
 462                  nhi->if_index, addr_to_a (ri->af, nhi->gateway),
 463                  nhi->recursive ? "yes" : "no",
 464                  nexthop_type_to_str (nhi->type));
 465     }
 466 }
 467
 468 /*
 469  * zfpm_netlink_encode_route
 470  *
 471  * Create a netlink message corresponding to the given route in the
 472  * given buffer space.
 473  *
 474  * Returns the number of bytes written to the buffer. 0 or a negative
 475  * value indicates an error.
 476  */
 477 int
 478 zfpm_netlink_encode_route (int cmd, rib_dest_t *dest, struct rib *rib,
 479                            char *in_buf, size_t in_buf_len)
 480 {
 481   netlink_route_info_t ri_space, *ri;
 482
 483   ri = &ri_space;
 484
 485   if (!netlink_route_info_fill (ri, cmd, dest, rib))
 486     return 0;
 487
 488   zfpm_log_route_info (ri, __FUNCTION__);
 489
 490   return netlink_route_info_encode (ri, in_buf, in_buf_len);
 491 }