bgpd/bgp_label.c

   1 /* BGP carrying label information
   2  * Copyright (C) 2013 Cumulus Networks, Inc.
   3  *
   4  * This file is part of GNU Zebra.
   5  *
   6  * GNU Zebra is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License as published by the
   8  * Free Software Foundation; either version 2, or (at your option) any
   9  * later version.
  10  *
  11  * GNU Zebra is distributed in the hope that it will be useful, but
  12  * WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License along
  17  * with this program; see the file COPYING; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
  19  */
  20
  21 #include <zebra.h>
  22
  23 #include "command.h"
  24 #include "thread.h"
  25 #include "prefix.h"
  26 #include "zclient.h"
  27 #include "stream.h"
  28 #include "network.h"
  29 #include "log.h"
  30 #include "memory.h"
  31 #include "nexthop.h"
  32 #include "mpls.h"
  33
  34 #include "bgpd/bgpd.h"
  35 #include "bgpd/bgp_table.h"
  36 #include "bgpd/bgp_route.h"
  37 #include "bgpd/bgp_attr.h"
  38 #include "bgpd/bgp_label.h"
  39 #include "bgpd/bgp_packet.h"
  40 #include "bgpd/bgp_debug.h"
  41
  42 extern struct zclient *zclient;
  43
  44 int bgp_parse_fec_update(void)
  45 {
  46         struct stream *s;
  47         struct bgp_node *rn;
  48         struct bgp *bgp;
  49         struct bgp_table *table;
  50         struct prefix p;
  51         u_int32_t label;
  52         afi_t afi;
  53         safi_t safi;
  54
  55         s = zclient->ibuf;
  56
  57         memset(&p, 0, sizeof(struct prefix));
  58         p.family = stream_getw(s);
  59         p.prefixlen = stream_getc(s);
  60         stream_get(&p.u.prefix, s, PSIZE(p.prefixlen));
  61         label = stream_getl(s);
  62
  63         /* hack for the bgp instance & SAFI = have to send/receive it */
  64         afi = family2afi(p.family);
  65         safi = SAFI_UNICAST;
  66         bgp = bgp_get_default();
  67         if (!bgp) {
  68                 zlog_debug("no default bgp instance");
  69                 return -1;
  70         }
  71
  72         table = bgp->rib[afi][safi];
  73         if (!table) {
  74                 zlog_debug("no %u unicast table", p.family);
  75                 return -1;
  76         }
  77         rn = bgp_node_lookup(table, &p);
  78         if (!rn) {
  79                 zlog_debug("no node for the prefix");
  80                 return -1;
  81         }
  82
  83         /* treat it as implicit withdraw - the label is invalid */
  84         if (label == MPLS_INVALID_LABEL)
  85                 bgp_unset_valid_label(&rn->local_label);
  86         else {
  87                 label_ntop(label, 1, &rn->local_label);
  88                 bgp_set_valid_label(&rn->local_label);
  89         }
  90         SET_FLAG(rn->flags, BGP_NODE_LABEL_CHANGED);
  91         bgp_unlock_node(rn);
  92         bgp_process(bgp, rn, afi, safi);
  93         return 1;
  94 }
  95
  96 mpls_label_t bgp_adv_label(struct bgp_node *rn, struct bgp_info *ri,
  97                            struct peer *to, afi_t afi, safi_t safi)
  98 {
  99         struct peer *from;
 100         mpls_label_t remote_label;
 101         int reflect;
 102
 103         if (!rn || !ri || !to)
 104                 return MPLS_INVALID_LABEL;
 105
 106         remote_label = ri->extra ? ri->extra->label : MPLS_INVALID_LABEL;
 107         from = ri->peer;
 108         reflect =
 109                 ((from->sort == BGP_PEER_IBGP) && (to->sort == BGP_PEER_IBGP));
 110
 111         if (reflect
 112             && !CHECK_FLAG(to->af_flags[afi][safi],
 113                            PEER_FLAG_FORCE_NEXTHOP_SELF))
 114                 return remote_label;
 115
 116         if (CHECK_FLAG(to->af_flags[afi][safi], PEER_FLAG_NEXTHOP_UNCHANGED))
 117                 return remote_label;
 118
 119         return rn->local_label;
 120 }
 121
 122 void bgp_reg_dereg_for_label(struct bgp_node *rn, struct bgp_info *ri, int reg)
 123 {
 124         struct stream *s;
 125         struct prefix *p;
 126         int command;
 127         u_int16_t flags = 0;
 128         size_t flags_pos = 0;
 129
 130         /* Check socket. */
 131         if (!zclient || zclient->sock < 0)
 132                 return;
 133
 134         p = &(rn->p);
 135         s = zclient->obuf;
 136         stream_reset(s);
 137         command = (reg) ? ZEBRA_FEC_REGISTER : ZEBRA_FEC_UNREGISTER;
 138         zclient_create_header(s, command, VRF_DEFAULT);
 139         flags_pos = stream_get_endp(s); /* save position of 'flags' */
 140         stream_putw(s, flags);          /* initial flags */
 141         stream_putw(s, PREFIX_FAMILY(p));
 142         stream_put_prefix(s, p);
 143         if (reg) {
 144                 assert(ri);
 145                 if (ri->attr->flag & ATTR_FLAG_BIT(BGP_ATTR_PREFIX_SID)) {
 146                         if (ri->attr->label_index != BGP_INVALID_LABEL_INDEX) {
 147                                 flags |= ZEBRA_FEC_REGISTER_LABEL_INDEX;
 148                                 stream_putl(s, ri->attr->label_index);
 149                         }
 150                 }
 151                 SET_FLAG(rn->flags, BGP_NODE_REGISTERED_FOR_LABEL);
 152         } else
 153                 UNSET_FLAG(rn->flags, BGP_NODE_REGISTERED_FOR_LABEL);
 154
 155         /* Set length and flags */
 156         stream_putw_at(s, 0, stream_get_endp(s));
 157         stream_putw_at(s, flags_pos, flags);
 158
 159         zclient_send_message(zclient);
 160 }
 161
 162 static int bgp_nlri_get_labels(struct peer *peer, u_char *pnt, u_char plen,
 163                                mpls_label_t *label)
 164 {
 165         u_char *data = pnt;
 166         u_char *lim = pnt + plen;
 167         u_char llen = 0;
 168         u_char label_depth = 0;
 169
 170         for (; data < lim; data += BGP_LABEL_BYTES) {
 171                 memcpy(label, data, BGP_LABEL_BYTES);
 172                 llen += BGP_LABEL_BYTES;
 173
 174                 bgp_set_valid_label(label);
 175                 label_depth += 1;
 176
 177                 if (bgp_is_withdraw_label(label) || label_bos(label))
 178                         break;
 179         }
 180
 181         /* If we RX multiple labels we will end up keeping only the last
 182          * one. We do not yet support a label stack greater than 1. */
 183         if (label_depth > 1)
 184                 zlog_warn("%s rcvd UPDATE with label stack %d deep", peer->host,
 185                           label_depth);
 186
 187         if (!(bgp_is_withdraw_label(label) || label_bos(label)))
 188                 zlog_warn(
 189                         "%s rcvd UPDATE with invalid label stack - no bottom of stack",
 190                         peer->host);
 191
 192         return llen;
 193 }
 194
 195 int bgp_nlri_parse_label(struct peer *peer, struct attr *attr,
 196                          struct bgp_nlri *packet)
 197 {
 198         u_char *pnt;
 199         u_char *lim;
 200         struct prefix p;
 201         int psize = 0;
 202         int prefixlen;
 203         afi_t afi;
 204         safi_t safi;
 205         int addpath_encoded;
 206         u_int32_t addpath_id;
 207         mpls_label_t label = MPLS_INVALID_LABEL;
 208         u_char llen;
 209
 210         /* Check peer status. */
 211         if (peer->status != Established)
 212                 return 0;
 213
 214         pnt = packet->nlri;
 215         lim = pnt + packet->length;
 216         afi = packet->afi;
 217         safi = packet->safi;
 218         addpath_id = 0;
 219
 220         addpath_encoded =
 221                 (CHECK_FLAG(peer->af_cap[afi][safi], PEER_CAP_ADDPATH_AF_RX_ADV)
 222                  && CHECK_FLAG(peer->af_cap[afi][safi],
 223                                PEER_CAP_ADDPATH_AF_TX_RCV));
 224
 225         for (; pnt < lim; pnt += psize) {
 226                 /* Clear prefix structure. */
 227                 memset(&p, 0, sizeof(struct prefix));
 228                 llen = 0;
 229
 230                 if (addpath_encoded) {
 231
 232                         /* When packet overflow occurs return immediately. */
 233                         if (pnt + BGP_ADDPATH_ID_LEN > lim)
 234                                 return -1;
 235
 236                         addpath_id = ntohl(*((uint32_t *)pnt));
 237                         pnt += BGP_ADDPATH_ID_LEN;
 238                 }
 239
 240                 /* Fetch prefix length. */
 241                 prefixlen = *pnt++;
 242                 p.family = afi2family(packet->afi);
 243                 psize = PSIZE(prefixlen);
 244
 245                 /* sanity check against packet data */
 246                 if ((pnt + psize) > lim) {
 247                         zlog_err(
 248                                 "%s [Error] Update packet error / L-U (prefix length %d exceeds packet size %u)",
 249                                 peer->host, prefixlen, (uint)(lim - pnt));
 250                         return -1;
 251                 }
 252
 253                 /* Fill in the labels */
 254                 llen = bgp_nlri_get_labels(peer, pnt, psize, &label);
 255                 p.prefixlen = prefixlen - BSIZE(llen);
 256
 257                 /* There needs to be at least one label */
 258                 if (prefixlen < 24) {
 259                         zlog_err(
 260                                 "%s [Error] Update packet error"
 261                                 " (wrong label length %d)",
 262                                 peer->host, prefixlen);
 263                         bgp_notify_send(peer, BGP_NOTIFY_UPDATE_ERR,
 264                                         BGP_NOTIFY_UPDATE_INVAL_NETWORK);
 265                         return -1;
 266                 }
 267
 268                 if ((afi == AFI_IP && p.prefixlen > 32)
 269                     || (afi == AFI_IP6 && p.prefixlen > 128))
 270                         return -1;
 271
 272                 /* Fetch prefix from NLRI packet */
 273                 memcpy(&p.u.prefix, pnt + llen, psize - llen);
 274
 275                 /* Check address. */
 276                 if (afi == AFI_IP && safi == SAFI_LABELED_UNICAST) {
 277                         if (IN_CLASSD(ntohl(p.u.prefix4.s_addr))) {
 278                                 /* From RFC4271 Section 6.3:
 279                                  *
 280                                  * If a prefix in the NLRI field is semantically
 281                                  * incorrect
 282                                  * (e.g., an unexpected multicast IP address),
 283                                  * an error SHOULD
 284                                  * be logged locally, and the prefix SHOULD be
 285                                  * ignored.
 286                                   */
 287                                 zlog_err(
 288                                         "%s: IPv4 labeled-unicast NLRI is multicast address %s, ignoring",
 289                                         peer->host, inet_ntoa(p.u.prefix4));
 290                                 continue;
 291                         }
 292                 }
 293
 294                 /* Check address. */
 295                 if (afi == AFI_IP6 && safi == SAFI_LABELED_UNICAST) {
 296                         if (IN6_IS_ADDR_LINKLOCAL(&p.u.prefix6)) {
 297                                 char buf[BUFSIZ];
 298
 299                                 zlog_err(
 300                                         "%s: IPv6 labeled-unicast NLRI is link-local address %s, ignoring",
 301                                         peer->host,
 302                                         inet_ntop(AF_INET6, &p.u.prefix6, buf,
 303                                                   BUFSIZ));
 304
 305                                 continue;
 306                         }
 307
 308                         if (IN6_IS_ADDR_MULTICAST(&p.u.prefix6)) {
 309                                 char buf[BUFSIZ];
 310
 311                                 zlog_err(
 312                                         "%s: IPv6 unicast NLRI is multicast address %s, ignoring",
 313                                         peer->host,
 314                                         inet_ntop(AF_INET6, &p.u.prefix6, buf,
 315                                                   BUFSIZ));
 316
 317                                 continue;
 318                         }
 319                 }
 320
 321                 if (attr) {
 322                         bgp_update(peer, &p, addpath_id, attr, packet->afi,
 323                                    SAFI_UNICAST, ZEBRA_ROUTE_BGP,
 324                                    BGP_ROUTE_NORMAL, NULL, &label, 0, NULL);
 325                 } else {
 326                         bgp_withdraw(peer, &p, addpath_id, attr, packet->afi,
 327                                      SAFI_UNICAST, ZEBRA_ROUTE_BGP,
 328                                      BGP_ROUTE_NORMAL, NULL, &label, NULL);
 329                 }
 330         }
 331
 332         /* Packet length consistency check. */
 333         if (pnt != lim) {
 334                 zlog_err(
 335                         "%s [Error] Update packet error / L-U (%zu data remaining after parsing)",
 336                         peer->host, lim - pnt);
 337                 return -1;
 338         }
 339
 340         return 0;
 341 }