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
 141    */
 142   netlink_nh_info_t nhs[MULTIPATH_NUM];
 143   union g_addr *pref_src;
 144 } netlink_route_info_t;
 145
 146 /*
 147  * netlink_route_info_add_nh
 148  *
 149  * Add information about the given nexthop to the given route info
 150  * structure.
 151  *
 152  * Returns TRUE if a nexthop was added, FALSE otherwise.
 153  */
 154 static int
 155 netlink_route_info_add_nh (netlink_route_info_t *ri, struct nexthop *nexthop,
 156                            int recursive)
 157 {
 158   netlink_nh_info_t nhi;
 159   union g_addr *src;
 160
 161   memset (&nhi, 0, sizeof (nhi));
 162   src = NULL;
 163
 164   if (ri->num_nhs >= (int) ZEBRA_NUM_OF (ri->nhs))
 165     return 0;
 166
 167   nhi.recursive = recursive;
 168   nhi.type = nexthop->type;
 169   nhi.if_index = nexthop->ifindex;
 170
 171   if (nexthop->type == NEXTHOP_TYPE_IPV4
 172       || nexthop->type == NEXTHOP_TYPE_IPV4_IFINDEX)
 173     {
 174       nhi.gateway = &nexthop->gate;
 175       if (nexthop->src.ipv4.s_addr)
 176         src = &nexthop->src;
 177     }
 178
 179   if (nexthop->type == NEXTHOP_TYPE_IPV6
 180       || nexthop->type == NEXTHOP_TYPE_IPV6_IFINDEX)
 181     {
 182       nhi.gateway = &nexthop->gate;
 183     }
 184
 185   if (nexthop->type == NEXTHOP_TYPE_IFINDEX)
 186     {
 187       if (nexthop->src.ipv4.s_addr)
 188         src = &nexthop->src;
 189     }
 190
 191   if (!nhi.gateway && nhi.if_index == 0)
 192     return 0;
 193
 194   /*
 195    * We have a valid nhi. Copy the structure over to the route_info.
 196    */
 197   ri->nhs[ri->num_nhs] = nhi;
 198   ri->num_nhs++;
 199
 200   if (src && !ri->pref_src)
 201     ri->pref_src = src;
 202
 203   return 1;
 204 }
 205
 206 /*
 207  * netlink_proto_from_route_type
 208  */
 209 static u_char
 210 netlink_proto_from_route_type (int type)
 211 {
 212   switch (type)
 213     {
 214     case ZEBRA_ROUTE_KERNEL:
 215     case ZEBRA_ROUTE_CONNECT:
 216       return RTPROT_KERNEL;
 217
 218     default:
 219       return RTPROT_ZEBRA;
 220     }
 221 }
 222
 223 /*
 224  * netlink_route_info_fill
 225  *
 226  * Fill out the route information object from the given route.
 227  *
 228  * Returns TRUE on success and FALSE on failure.
 229  */
 230 static int
 231 netlink_route_info_fill (netlink_route_info_t *ri, int cmd,
 232                          rib_dest_t *dest, struct rib *rib)
 233 {
 234   struct nexthop *nexthop, *tnexthop;
 235   int recursing;
 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 = rib_dest_vrf (dest)->vrf_id;
 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 && !rib)
 252     goto skip;
 253
 254   if (rib)
 255     ri->rtm_protocol = netlink_proto_from_route_type (rib->type);
 256
 257   if ((rib->flags & ZEBRA_FLAG_BLACKHOLE) || (rib->flags & ZEBRA_FLAG_REJECT))
 258     discard = 1;
 259   else
 260     discard = 0;
 261
 262   if (cmd == RTM_NEWROUTE)
 263     {
 264       if (discard)
 265         {
 266           if (rib->flags & ZEBRA_FLAG_BLACKHOLE)
 267             ri->rtm_type = RTN_BLACKHOLE;
 268           else if (rib->flags & ZEBRA_FLAG_REJECT)
 269             ri->rtm_type = RTN_UNREACHABLE;
 270           else
 271             assert (0);
 272         }
 273       else
 274         ri->rtm_type = RTN_UNICAST;
 275     }
 276
 277   ri->metric = &rib->metric;
 278
 279   if (discard)
 280     {
 281       goto skip;
 282     }
 283
 284   for (ALL_NEXTHOPS_RO(rib->nexthop, nexthop, tnexthop, recursing))
 285     {
 286       if (ri->num_nhs >= MULTIPATH_NUM)
 287         break;
 288
 289       if (CHECK_FLAG(nexthop->flags, NEXTHOP_FLAG_RECURSIVE))
 290         continue;
 291
 292       if ((cmd == RTM_NEWROUTE
 293            && CHECK_FLAG (nexthop->flags, NEXTHOP_FLAG_ACTIVE))
 294           || (cmd == RTM_DELROUTE
 295               && CHECK_FLAG (nexthop->flags, NEXTHOP_FLAG_FIB)))
 296         {
 297           netlink_route_info_add_nh (ri, nexthop, recursing);
 298         }
 299     }
 300
 301   /* If there is no useful nexthop then return. */
 302   if (ri->num_nhs == 0)
 303     {
 304       zfpm_debug ("netlink_encode_route(): No useful nexthop.");
 305       return 0;
 306     }
 307
 308  skip:
 309   return 1;
 310 }
 311
 312 /*
 313  * netlink_route_info_encode
 314  *
 315  * Returns the number of bytes written to the buffer. 0 or a negative
 316  * value indicates an error.
 317  */
 318 static int
 319 netlink_route_info_encode (netlink_route_info_t *ri, char *in_buf,
 320                            size_t in_buf_len)
 321 {
 322   int bytelen;
 323   int nexthop_num = 0;
 324   size_t buf_offset;
 325   netlink_nh_info_t *nhi;
 326
 327   struct
 328   {
 329     struct nlmsghdr n;
 330     struct rtmsg r;
 331     char buf[1];
 332   } *req;
 333
 334   req = (void *) in_buf;
 335
 336   buf_offset = ((char *) req->buf) - ((char *) req);
 337
 338   if (in_buf_len < buf_offset) {
 339     assert(0);
 340     return 0;
 341   }
 342
 343   memset (req, 0, buf_offset);
 344
 345   bytelen = af_addr_size (ri->af);
 346
 347   req->n.nlmsg_len = NLMSG_LENGTH (sizeof (struct rtmsg));
 348   req->n.nlmsg_flags = NLM_F_CREATE | NLM_F_REQUEST;
 349   req->n.nlmsg_type = ri->nlmsg_type;
 350   req->r.rtm_family = ri->af;
 351   req->r.rtm_table = ri->rtm_table;
 352   req->r.rtm_dst_len = ri->prefix->prefixlen;
 353   req->r.rtm_protocol = ri->rtm_protocol;
 354   req->r.rtm_scope = RT_SCOPE_UNIVERSE;
 355
 356   addattr_l (&req->n, in_buf_len, RTA_DST, &ri->prefix->u.prefix, bytelen);
 357
 358   req->r.rtm_type = ri->rtm_type;
 359
 360   /* Metric. */
 361   if (ri->metric)
 362     addattr32 (&req->n, in_buf_len, RTA_PRIORITY, *ri->metric);
 363
 364   if (ri->num_nhs == 0)
 365     goto done;
 366
 367   if (ri->num_nhs == 1)
 368     {
 369       nhi = &ri->nhs[0];
 370
 371       if (nhi->gateway)
 372         {
 373           addattr_l (&req->n, in_buf_len, RTA_GATEWAY, nhi->gateway,
 374                      bytelen);
 375         }
 376
 377       if (nhi->if_index)
 378         {
 379           addattr32 (&req->n, in_buf_len, RTA_OIF, nhi->if_index);
 380         }
 381
 382       goto done;
 383
 384     }
 385
 386   /*
 387    * Multipath case.
 388    */
 389   char buf[NL_PKT_BUF_SIZE];
 390   struct rtattr *rta = (void *) buf;
 391   struct rtnexthop *rtnh;
 392
 393   rta->rta_type = RTA_MULTIPATH;
 394   rta->rta_len = RTA_LENGTH (0);
 395   rtnh = RTA_DATA (rta);
 396
 397   for (nexthop_num = 0; nexthop_num < ri->num_nhs; nexthop_num++)
 398     {
 399       nhi = &ri->nhs[nexthop_num];
 400
 401       rtnh->rtnh_len = sizeof (*rtnh);
 402       rtnh->rtnh_flags = 0;
 403       rtnh->rtnh_hops = 0;
 404       rtnh->rtnh_ifindex = 0;
 405       rta->rta_len += rtnh->rtnh_len;
 406
 407       if (nhi->gateway)
 408         {
 409           rta_addattr_l (rta, sizeof (buf), RTA_GATEWAY, nhi->gateway, bytelen);
 410           rtnh->rtnh_len += sizeof (struct rtattr) + bytelen;
 411         }
 412
 413       if (nhi->if_index)
 414         {
 415           rtnh->rtnh_ifindex = nhi->if_index;
 416         }
 417
 418       rtnh = RTNH_NEXT (rtnh);
 419     }
 420
 421   assert (rta->rta_len > RTA_LENGTH (0));
 422   addattr_l (&req->n, in_buf_len, RTA_MULTIPATH, RTA_DATA (rta),
 423              RTA_PAYLOAD (rta));
 424
 425 done:
 426
 427   if (ri->pref_src)
 428     {
 429       addattr_l (&req->n, in_buf_len, RTA_PREFSRC, &ri->pref_src, bytelen);
 430     }
 431
 432   assert (req->n.nlmsg_len < in_buf_len);
 433   return req->n.nlmsg_len;
 434 }
 435
 436 /*
 437  * zfpm_log_route_info
 438  *
 439  * Helper function to log the information in a route_info structure.
 440  */
 441 static void
 442 zfpm_log_route_info (netlink_route_info_t *ri, const char *label)
 443 {
 444   netlink_nh_info_t *nhi;
 445   int i;
 446
 447   zfpm_debug ("%s : %s %s/%d, Proto: %s, Metric: %u", label,
 448               nl_msg_type_to_str (ri->nlmsg_type),
 449               prefix_addr_to_a (ri->prefix), ri->prefix->prefixlen,
 450               nl_rtproto_to_str (ri->rtm_protocol),
 451               ri->metric ? *ri->metric : 0);
 452
 453   for (i = 0; i < ri->num_nhs; i++)
 454     {
 455       nhi = &ri->nhs[i];
 456       zfpm_debug("  Intf: %u, Gateway: %s, Recursive: %s, Type: %s",
 457                  nhi->if_index, addr_to_a (ri->af, nhi->gateway),
 458                  nhi->recursive ? "yes" : "no",
 459                  nexthop_type_to_str (nhi->type));
 460     }
 461 }
 462
 463 /*
 464  * zfpm_netlink_encode_route
 465  *
 466  * Create a netlink message corresponding to the given route in the
 467  * given buffer space.
 468  *
 469  * Returns the number of bytes written to the buffer. 0 or a negative
 470  * value indicates an error.
 471  */
 472 int
 473 zfpm_netlink_encode_route (int cmd, rib_dest_t *dest, struct rib *rib,
 474                            char *in_buf, size_t in_buf_len)
 475 {
 476   netlink_route_info_t ri_space, *ri;
 477
 478   ri = &ri_space;
 479
 480   if (!netlink_route_info_fill (ri, cmd, dest, rib))
 481     return 0;
 482
 483   zfpm_log_route_info (ri, __FUNCTION__);
 484
 485   return netlink_route_info_encode (ri, in_buf, in_buf_len);
 486 }