diff options
Diffstat (limited to 'bgpd/bgp_mpath.c')
| -rw-r--r-- | bgpd/bgp_mpath.c | 737 |
1 files changed, 737 insertions, 0 deletions
diff --git a/bgpd/bgp_mpath.c b/bgpd/bgp_mpath.c new file mode 100644 index 00000000..d07830d1 --- /dev/null +++ b/bgpd/bgp_mpath.c @@ -0,0 +1,737 @@ +/* $QuaggaId: Format:%an, %ai, %h$ $ + * + * BGP Multipath + * Copyright (C) 2010 Google Inc. + * + * This file is part of Quagga + * + * Quagga is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License as published by the + * Free Software Foundation; either version 2, or (at your option) any + * later version. + * + * Quagga is distributed in the hope that it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with Quagga; see the file COPYING. If not, write to the Free + * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA + * 02111-1307, USA. + */ + +#include <zebra.h> + +#include "command.h" +#include "prefix.h" +#include "linklist.h" +#include "sockunion.h" +#include "memory.h" + +#include "bgpd/bgpd.h" +#include "bgpd/bgp_table.h" +#include "bgpd/bgp_route.h" +#include "bgpd/bgp_attr.h" +#include "bgpd/bgp_debug.h" +#include "bgpd/bgp_aspath.h" +#include "bgpd/bgp_community.h" +#include "bgpd/bgp_ecommunity.h" +#include "bgpd/bgp_mpath.h" + +/* + * bgp_maximum_paths_set + * + * Record maximum-paths configuration for BGP instance + */ +int +bgp_maximum_paths_set (struct bgp *bgp, afi_t afi, safi_t safi, + int peertype, u_int16_t maxpaths) +{ + if (!bgp || (afi >= AFI_MAX) || (safi >= SAFI_MAX)) + return -1; + + switch (peertype) + { + case BGP_PEER_IBGP: + bgp->maxpaths[afi][safi].maxpaths_ibgp = maxpaths; + break; + case BGP_PEER_EBGP: + bgp->maxpaths[afi][safi].maxpaths_ebgp = maxpaths; + break; + default: + return -1; + } + + return 0; +} + +/* + * bgp_maximum_paths_unset + * + * Remove maximum-paths configuration from BGP instance + */ +int +bgp_maximum_paths_unset (struct bgp *bgp, afi_t afi, safi_t safi, + int peertype) +{ + if (!bgp || (afi >= AFI_MAX) || (safi >= SAFI_MAX)) + return -1; + + switch (peertype) + { + case BGP_PEER_IBGP: + bgp->maxpaths[afi][safi].maxpaths_ibgp = BGP_DEFAULT_MAXPATHS; + break; + case BGP_PEER_EBGP: + bgp->maxpaths[afi][safi].maxpaths_ebgp = BGP_DEFAULT_MAXPATHS; + break; + default: + return -1; + } + + return 0; +} + +/* + * bgp_info_nexthop_cmp + * + * Compare the nexthops of two paths. Return value is less than, equal to, + * or greater than zero if bi1 is respectively less than, equal to, + * or greater than bi2. + */ +static int +bgp_info_nexthop_cmp (struct bgp_info *bi1, struct bgp_info *bi2) +{ + struct attr_extra *ae1, *ae2; + int compare; + + ae1 = bi1->attr->extra; + ae2 = bi2->attr->extra; + + compare = IPV4_ADDR_CMP (&bi1->attr->nexthop, &bi2->attr->nexthop); + + if (!compare && ae1 && ae2 && (ae1->mp_nexthop_len == ae2->mp_nexthop_len)) + { + switch (ae1->mp_nexthop_len) + { + case 4: + case 12: + compare = IPV4_ADDR_CMP (&ae1->mp_nexthop_global_in, + &ae2->mp_nexthop_global_in); + break; +#ifdef HAVE_IPV6 + case 16: + compare = IPV6_ADDR_CMP (&ae1->mp_nexthop_global, + &ae2->mp_nexthop_global); + break; + case 32: + compare = IPV6_ADDR_CMP (&ae1->mp_nexthop_global, + &ae2->mp_nexthop_global); + if (!compare) + compare = IPV6_ADDR_CMP (&ae1->mp_nexthop_local, + &ae2->mp_nexthop_local); + break; +#endif /* HAVE_IPV6 */ + } + } + + return compare; +} + +/* + * bgp_info_mpath_cmp + * + * This function determines our multipath list ordering. By ordering + * the list we can deterministically select which paths are included + * in the multipath set. The ordering also helps in detecting changes + * in the multipath selection so we can detect whether to send an + * update to zebra. + * + * The order of paths is determined first by received nexthop, and then + * by peer address if the nexthops are the same. + */ +static int +bgp_info_mpath_cmp (void *val1, void *val2) +{ + struct bgp_info *bi1, *bi2; + int compare; + + bi1 = val1; + bi2 = val2; + + compare = bgp_info_nexthop_cmp (bi1, bi2); + + if (!compare) + compare = sockunion_cmp (bi1->peer->su_remote, bi2->peer->su_remote); + + return compare; +} + +/* + * bgp_mp_list_init + * + * Initialize the mp_list, which holds the list of multipaths + * selected by bgp_best_selection + */ +void +bgp_mp_list_init (struct list *mp_list) +{ + assert (mp_list); + memset (mp_list, 0, sizeof (struct list)); + mp_list->cmp = bgp_info_mpath_cmp; +} + +/* + * bgp_mp_list_clear + * + * Clears all entries out of the mp_list + */ +void +bgp_mp_list_clear (struct list *mp_list) +{ + assert (mp_list); + list_delete_all_node (mp_list); +} + +/* + * bgp_mp_list_add + * + * Adds a multipath entry to the mp_list + */ +void +bgp_mp_list_add (struct list *mp_list, struct bgp_info *mpinfo) +{ + assert (mp_list && mpinfo); + listnode_add_sort (mp_list, mpinfo); +} + +/* + * bgp_info_mpath_new + * + * Allocate and zero memory for a new bgp_info_mpath element + */ +static struct bgp_info_mpath * +bgp_info_mpath_new (void) +{ + struct bgp_info_mpath *new_mpath; + new_mpath = XCALLOC (MTYPE_BGP_MPATH_INFO, sizeof (struct bgp_info_mpath)); + return new_mpath; +} + +/* + * bgp_info_mpath_free + * + * Release resources for a bgp_info_mpath element and zero out pointer + */ +void +bgp_info_mpath_free (struct bgp_info_mpath **mpath) +{ + if (mpath && *mpath) + { + if ((*mpath)->mp_attr) + bgp_attr_unintern ((*mpath)->mp_attr); + XFREE (MTYPE_BGP_MPATH_INFO, *mpath); + *mpath = NULL; + } +} + +/* + * bgp_info_mpath_get + * + * Fetch the mpath element for the given bgp_info. Used for + * doing lazy allocation. + */ +static struct bgp_info_mpath * +bgp_info_mpath_get (struct bgp_info *binfo) +{ + struct bgp_info_mpath *mpath; + if (!binfo->mpath) + { + mpath = bgp_info_mpath_new(); + if (!mpath) + return NULL; + binfo->mpath = mpath; + mpath->mp_info = binfo; + } + return binfo->mpath; +} + +/* + * bgp_info_mpath_enqueue + * + * Enqueue a path onto the multipath list given the previous multipath + * list entry + */ +static void +bgp_info_mpath_enqueue (struct bgp_info *prev_info, struct bgp_info *binfo) +{ + struct bgp_info_mpath *prev, *mpath; + + prev = bgp_info_mpath_get (prev_info); + mpath = bgp_info_mpath_get (binfo); + if (!prev || !mpath) + return; + + mpath->mp_next = prev->mp_next; + mpath->mp_prev = prev; + if (prev->mp_next) + prev->mp_next->mp_prev = mpath; + prev->mp_next = mpath; + + SET_FLAG (binfo->flags, BGP_INFO_MULTIPATH); +} + +/* + * bgp_info_mpath_dequeue + * + * Remove a path from the multipath list + */ +void +bgp_info_mpath_dequeue (struct bgp_info *binfo) +{ + struct bgp_info_mpath *mpath = binfo->mpath; + if (!mpath) + return; + if (mpath->mp_prev) + mpath->mp_prev->mp_next = mpath->mp_next; + if (mpath->mp_next) + mpath->mp_next->mp_prev = mpath->mp_prev; + mpath->mp_next = mpath->mp_prev = NULL; + UNSET_FLAG (binfo->flags, BGP_INFO_MULTIPATH); +} + +/* + * bgp_info_mpath_next + * + * Given a bgp_info, return the next multipath entry + */ +struct bgp_info * +bgp_info_mpath_next (struct bgp_info *binfo) +{ + if (!binfo->mpath || !binfo->mpath->mp_next) + return NULL; + return binfo->mpath->mp_next->mp_info; +} + +/* + * bgp_info_mpath_first + * + * Given bestpath bgp_info, return the first multipath entry. + */ +struct bgp_info * +bgp_info_mpath_first (struct bgp_info *binfo) +{ + return bgp_info_mpath_next (binfo); +} + +/* + * bgp_info_mpath_count + * + * Given the bestpath bgp_info, return the number of multipath entries + */ +u_int32_t +bgp_info_mpath_count (struct bgp_info *binfo) +{ + if (!binfo->mpath) + return 0; + return binfo->mpath->mp_count; +} + +/* + * bgp_info_mpath_count_set + * + * Sets the count of multipaths into bestpath's mpath element + */ +static void +bgp_info_mpath_count_set (struct bgp_info *binfo, u_int32_t count) +{ + struct bgp_info_mpath *mpath; + if (!count && !binfo->mpath) + return; + mpath = bgp_info_mpath_get (binfo); + if (!mpath) + return; + mpath->mp_count = count; +} + +/* + * bgp_info_mpath_attr + * + * Given bestpath bgp_info, return aggregated attribute set used + * for advertising the multipath route + */ +struct attr * +bgp_info_mpath_attr (struct bgp_info *binfo) +{ + if (!binfo->mpath) + return NULL; + return binfo->mpath->mp_attr; +} + +/* + * bgp_info_mpath_attr_set + * + * Sets the aggregated attribute into bestpath's mpath element + */ +static void +bgp_info_mpath_attr_set (struct bgp_info *binfo, struct attr *attr) +{ + struct bgp_info_mpath *mpath; + if (!attr && !binfo->mpath) + return; + mpath = bgp_info_mpath_get (binfo); + if (!mpath) + return; + mpath->mp_attr = attr; +} + +/* + * bgp_info_mpath_update + * + * Compare and sync up the multipath list with the mp_list generated by + * bgp_best_selection + */ +void +bgp_info_mpath_update (struct bgp_node *rn, struct bgp_info *new_best, + struct bgp_info *old_best, struct list *mp_list, + struct bgp_maxpaths_cfg *mpath_cfg) +{ + u_int16_t maxpaths, mpath_count, old_mpath_count; + struct listnode *mp_node, *mp_next_node; + struct bgp_info *cur_mpath, *new_mpath, *next_mpath, *prev_mpath; + int mpath_changed, debug; + char pfx_buf[INET_ADDRSTRLEN], nh_buf[2][INET_ADDRSTRLEN]; + + mpath_changed = 0; + maxpaths = BGP_DEFAULT_MAXPATHS; + mpath_count = 0; + cur_mpath = NULL; + old_mpath_count = 0; + prev_mpath = new_best; + mp_node = listhead (mp_list); + debug = BGP_DEBUG (events, EVENTS); + + if (debug) + prefix2str (&rn->p, pfx_buf, sizeof (pfx_buf)); + + if (new_best) + { + mpath_count++; + if (new_best != old_best) + bgp_info_mpath_dequeue (new_best); + maxpaths = (peer_sort (new_best->peer) == BGP_PEER_IBGP) ? + mpath_cfg->maxpaths_ibgp : mpath_cfg->maxpaths_ebgp; + } + + if (old_best) + { + cur_mpath = bgp_info_mpath_first (old_best); + old_mpath_count = bgp_info_mpath_count (old_best); + bgp_info_mpath_count_set (old_best, 0); + bgp_info_mpath_dequeue (old_best); + } + + /* + * We perform an ordered walk through both lists in parallel. + * The reason for the ordered walk is that if there are paths + * that were previously multipaths and are still multipaths, the walk + * should encounter them in both lists at the same time. Otherwise + * there will be paths that are in one list or another, and we + * will deal with these separately. + * + * Note that new_best might be somewhere in the mp_list, so we need + * to skip over it + */ + while (mp_node || cur_mpath) + { + /* + * We can bail out of this loop if all existing paths on the + * multipath list have been visited (for cleanup purposes) and + * the maxpath requirement is fulfulled + */ + if (!cur_mpath && (mpath_count >= maxpaths)) + break; + + mp_next_node = mp_node ? listnextnode (mp_node) : NULL; + next_mpath = cur_mpath ? bgp_info_mpath_next (cur_mpath) : NULL; + + /* + * If equal, the path was a multipath and is still a multipath. + * Insert onto new multipath list if maxpaths allows. + */ + if (mp_node && (listgetdata (mp_node) == cur_mpath)) + { + list_delete_node (mp_list, mp_node); + bgp_info_mpath_dequeue (cur_mpath); + if ((mpath_count < maxpaths) && + bgp_info_nexthop_cmp (prev_mpath, cur_mpath)) + { + bgp_info_mpath_enqueue (prev_mpath, cur_mpath); + prev_mpath = cur_mpath; + mpath_count++; + } + else + { + mpath_changed = 1; + if (debug) + zlog_debug ("%s remove mpath nexthop %s peer %s", pfx_buf, + inet_ntop (AF_INET, &cur_mpath->attr->nexthop, + nh_buf[0], sizeof (nh_buf[0])), + sockunion2str (cur_mpath->peer->su_remote, + nh_buf[1], sizeof (nh_buf[1]))); + } + mp_node = mp_next_node; + cur_mpath = next_mpath; + continue; + } + + if (cur_mpath && (!mp_node || + (bgp_info_mpath_cmp (cur_mpath, + listgetdata (mp_node)) < 0))) + { + /* + * If here, we have an old multipath and either the mp_list + * is finished or the next mp_node points to a later + * multipath, so we need to purge this path from the + * multipath list + */ + bgp_info_mpath_dequeue (cur_mpath); + mpath_changed = 1; + if (debug) + zlog_debug ("%s remove mpath nexthop %s peer %s", pfx_buf, + inet_ntop (AF_INET, &cur_mpath->attr->nexthop, + nh_buf[0], sizeof (nh_buf[0])), + sockunion2str (cur_mpath->peer->su_remote, + nh_buf[1], sizeof (nh_buf[1]))); + cur_mpath = next_mpath; + } + else + { + /* + * If here, we have a path on the mp_list that was not previously + * a multipath (due to non-equivalance or maxpaths exceeded), + * or the matching multipath is sorted later in the multipath + * list. Before we enqueue the path on the new multipath list, + * make sure its not on the old_best multipath list or referenced + * via next_mpath: + * - If next_mpath points to this new path, update next_mpath to + * point to the multipath after this one + * - Dequeue the path from the multipath list just to make sure + */ + new_mpath = listgetdata (mp_node); + list_delete_node (mp_list, mp_node); + if ((mpath_count < maxpaths) && (new_mpath != new_best) && + bgp_info_nexthop_cmp (prev_mpath, new_mpath)) + { + if (new_mpath == next_mpath) + next_mpath = bgp_info_mpath_next (new_mpath); + bgp_info_mpath_dequeue (new_mpath); + + bgp_info_mpath_enqueue (prev_mpath, new_mpath); + prev_mpath = new_mpath; + mpath_changed = 1; + mpath_count++; + if (debug) + zlog_debug ("%s add mpath nexthop %s peer %s", pfx_buf, + inet_ntop (AF_INET, &new_mpath->attr->nexthop, + nh_buf[0], sizeof (nh_buf[0])), + sockunion2str (new_mpath->peer->su_remote, + nh_buf[1], sizeof (nh_buf[1]))); + } + mp_node = mp_next_node; + } + } + + if (new_best) + { + bgp_info_mpath_count_set (new_best, mpath_count-1); + if (mpath_changed || (bgp_info_mpath_count (new_best) != old_mpath_count)) + SET_FLAG (new_best->flags, BGP_INFO_MULTIPATH_CHG); + } +} + +/* + * bgp_mp_dmed_deselect + * + * Clean up multipath information for BGP_INFO_DMED_SELECTED path that + * is not selected as best path + */ +void +bgp_mp_dmed_deselect (struct bgp_info *dmed_best) +{ + struct bgp_info *mpinfo, *mpnext; + + if (!dmed_best) + return; + + for (mpinfo = bgp_info_mpath_first (dmed_best); mpinfo; mpinfo = mpnext) + { + mpnext = bgp_info_mpath_next (mpinfo); + bgp_info_mpath_dequeue (mpinfo); + } + + bgp_info_mpath_count_set (dmed_best, 0); + UNSET_FLAG (dmed_best->flags, BGP_INFO_MULTIPATH_CHG); + assert (bgp_info_mpath_first (dmed_best) == 0); +} + +/* + * bgp_info_mpath_aggregate_update + * + * Set the multipath aggregate attribute. We need to see if the + * aggregate has changed and then set the ATTR_CHANGED flag on the + * bestpath info so that a peer update will be generated. The + * change is detected by generating the current attribute, + * interning it, and then comparing the interned pointer with the + * current value. We can skip this generate/compare step if there + * is no change in multipath selection and no attribute change in + * any multipath. + */ +void +bgp_info_mpath_aggregate_update (struct bgp_info *new_best, + struct bgp_info *old_best) +{ + struct bgp_info *mpinfo; + struct aspath *aspath; + struct aspath *asmerge; + struct attr *new_attr, *old_attr; + u_char origin, attr_chg; + struct community *community, *commerge; + struct ecommunity *ecomm, *ecommerge; + struct attr_extra *ae; + struct attr attr = { 0 }; + + if (old_best && (old_best != new_best) && + (old_attr = bgp_info_mpath_attr (old_best))) + { + bgp_attr_unintern (old_attr); + bgp_info_mpath_attr_set (old_best, NULL); + } + + if (!new_best) + return; + + if (!bgp_info_mpath_count (new_best)) + { + if ((new_attr = bgp_info_mpath_attr (new_best))) + { + bgp_attr_unintern (new_attr); + bgp_info_mpath_attr_set (new_best, NULL); + SET_FLAG (new_best->flags, BGP_INFO_ATTR_CHANGED); + } + return; + } + + /* + * Bail out here if the following is true: + * - MULTIPATH_CHG bit is not set on new_best, and + * - No change in bestpath, and + * - ATTR_CHANGED bit is not set on new_best or any of the multipaths + */ + if (!CHECK_FLAG (new_best->flags, BGP_INFO_MULTIPATH_CHG) && + (old_best == new_best)) + { + attr_chg = 0; + + if (CHECK_FLAG (new_best->flags, BGP_INFO_ATTR_CHANGED)) + attr_chg = 1; + else + for (mpinfo = bgp_info_mpath_first (new_best); mpinfo; + mpinfo = bgp_info_mpath_next (mpinfo)) + { + if (CHECK_FLAG (mpinfo->flags, BGP_INFO_ATTR_CHANGED)) + { + attr_chg = 1; + break; + } + } + + if (!attr_chg) + { + assert (bgp_info_mpath_attr (new_best)); + return; + } + } + + bgp_attr_dup (&attr, new_best->attr); + + /* aggregate attribute from multipath constituents */ + aspath = aspath_dup (attr.aspath); + origin = attr.origin; + community = attr.community ? community_dup (attr.community) : NULL; + ae = attr.extra; + ecomm = (ae && ae->ecommunity) ? ecommunity_dup (ae->ecommunity) : NULL; + + for (mpinfo = bgp_info_mpath_first (new_best); mpinfo; + mpinfo = bgp_info_mpath_next (mpinfo)) + { + asmerge = aspath_aggregate (aspath, mpinfo->attr->aspath); + aspath_free (aspath); + aspath = asmerge; + + if (origin < mpinfo->attr->origin) + origin = mpinfo->attr->origin; + + if (mpinfo->attr->community) + { + if (community) + { + commerge = community_merge (community, mpinfo->attr->community); + community = community_uniq_sort (commerge); + community_free (commerge); + } + else + community = community_dup (mpinfo->attr->community); + } + + ae = mpinfo->attr->extra; + if (ae && ae->ecommunity) + { + if (ecomm) + { + ecommerge = ecommunity_merge (ecomm, ae->ecommunity); + ecomm = ecommunity_uniq_sort (ecommerge); + ecommunity_free (ecommerge); + } + else + ecomm = ecommunity_dup (ae->ecommunity); + } + } + + attr.aspath = aspath; + attr.origin = origin; + if (community) + { + attr.community = community; + attr.flag |= ATTR_FLAG_BIT (BGP_ATTR_COMMUNITIES); + } + if (ecomm) + { + ae = bgp_attr_extra_get (&attr); + ae->ecommunity = ecomm; + attr.flag |= ATTR_FLAG_BIT (BGP_ATTR_EXT_COMMUNITIES); + } + + /* Zap multipath attr nexthop so we set nexthop to self */ + attr.nexthop.s_addr = 0; +#ifdef HAVE_IPV6 + if (attr.extra) + memset (&attr.extra->mp_nexthop_global, 0, sizeof (struct in6_addr)); +#endif /* HAVE_IPV6 */ + + /* TODO: should we set ATOMIC_AGGREGATE and AGGREGATOR? */ + + new_attr = bgp_attr_intern (&attr); + bgp_attr_extra_free (&attr); + + if (new_attr != bgp_info_mpath_attr (new_best)) + { + if ((old_attr = bgp_info_mpath_attr (new_best))) + bgp_attr_unintern (old_attr); + bgp_info_mpath_attr_set (new_best, new_attr); + SET_FLAG (new_best->flags, BGP_INFO_ATTR_CHANGED); + } + else + bgp_attr_unintern (new_attr); +} |