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 along
  21  * with this program; see the file COPYING; if not, write to the Free Software
  22  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
  23  */
  24
  25 #include <zebra.h>
  26
  27 #include "log.h"
  28 #include "rib.h"
  29 #include "vty.h"
  30 #include "prefix.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   unsigned 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 {
 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 = nexthop->rparent ? 1 : 0;
 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   if (nexthop->type == NEXTHOP_TYPE_IPV6
 181       || nexthop->type == NEXTHOP_TYPE_IPV6_IFINDEX)
 182     {
 183       nhi.gateway = &nexthop->gate;
 184     }
 185
 186   if (nexthop->type == NEXTHOP_TYPE_IFINDEX)
 187     {
 188       if (nexthop->src.ipv4.s_addr)
 189         src = &nexthop->src;
 190     }
 191
 192   if (!nhi.gateway && nhi.if_index == 0)
 193     return 0;
 194
 195   /*
 196    * We have a valid nhi. Copy the structure over to the route_info.
 197    */
 198   ri->nhs[ri->num_nhs] = nhi;
 199   ri->num_nhs++;
 200
 201   if (src && !ri->pref_src)
 202     ri->pref_src = src;
 203
 204   return 1;
 205 }
 206
 207 /*
 208  * netlink_proto_from_route_type
 209  */
 210 static u_char
 211 netlink_proto_from_route_type (int type)
 212 {
 213   switch (type)
 214     {
 215     case ZEBRA_ROUTE_KERNEL:
 216     case ZEBRA_ROUTE_CONNECT:
 217       return RTPROT_KERNEL;
 218
 219     default:
 220       return RTPROT_ZEBRA;
 221     }
 222 }
 223
 224 /*
 225  * netlink_route_info_fill
 226  *
 227  * Fill out the route information object from the given route.
 228  *
 229  * Returns TRUE on success and FALSE on failure.
 230  */
 231 static int
 232 netlink_route_info_fill (netlink_route_info_t *ri, int cmd,
 233                          rib_dest_t *dest, struct route_entry *re)
 234 {
 235   struct nexthop *nexthop;
 236   int discard;
 237
 238   memset (ri, 0, sizeof (*ri));
 239
 240   ri->prefix = rib_dest_prefix (dest);
 241   ri->af = rib_dest_af (dest);
 242
 243   ri->nlmsg_type = cmd;
 244   ri->rtm_table = zvrf_id (rib_dest_vrf (dest));
 245   ri->rtm_protocol = RTPROT_UNSPEC;
 246
 247   /*
 248    * An RTM_DELROUTE need not be accompanied by any nexthops,
 249    * particularly in our communication with the FPM.
 250    */
 251   if (cmd == RTM_DELROUTE && !re)
 252     return 1;
 253
 254   if (!re)
 255     {
 256       zfpm_debug ("%s: Expected non-NULL re pointer", __PRETTY_FUNCTION__);
 257       return 0;
 258     }
 259
 260   ri->rtm_protocol = netlink_proto_from_route_type (re->type);
 261
 262   if ((re->flags & ZEBRA_FLAG_BLACKHOLE) || (re->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 (re->flags & ZEBRA_FLAG_BLACKHOLE)
 272             ri->rtm_type = RTN_BLACKHOLE;
 273           else if (re->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 = &re->metric;
 283
 284   if (discard)
 285     return 1;
 286
 287   for (ALL_NEXTHOPS(re->nexthop, nexthop))
 288     {
 289       if (ri->num_nhs >= multipath_num)
 290         break;
 291
 292       if (CHECK_FLAG(nexthop->flags, NEXTHOP_FLAG_RECURSIVE))
 293         continue;
 294
 295       if ((cmd == RTM_NEWROUTE
 296            && CHECK_FLAG (nexthop->flags, NEXTHOP_FLAG_ACTIVE))
 297           || (cmd == RTM_DELROUTE
 298               && CHECK_FLAG (nexthop->flags, NEXTHOP_FLAG_FIB)))
 299         {
 300           netlink_route_info_add_nh (ri, nexthop);
 301         }
 302     }
 303
 304   /* If there is no useful nexthop then return. */
 305   if (ri->num_nhs == 0)
 306     {
 307       zfpm_debug ("netlink_encode_route(): No useful nexthop.");
 308       return 0;
 309     }
 310
 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   unsigned 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   unsigned 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 route_entry *re,
 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, re))
 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 }