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Author: Timo Teräs <timo.teras@iki.fi>
Date: Tue Sep 30 11:31:53 2014 +0300
bgpd: implement route-map set as-path prepend last-as
It picks up the AS to add from the aspath, or uses the peers
AS number. Useful mostly in iBGP setups.
Signed-off-by: Timo Teräs <timo.teras@iki.fi>
Reviewed-by: Paul Jakma <paul@opensourcerouting.org>
This commit is contained in:
Daniel Walton
parent
3a0d83b689
commit
bc3dd427f2
@ -490,6 +490,19 @@ aspath_highest (struct aspath *aspath)
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return highest;
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}
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/* Return the left-most ASN in path */
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as_t
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aspath_leftmost (struct aspath *aspath)
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{
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struct assegment *seg = aspath->segments;
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as_t leftmost = 0;
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if (seg && seg->length && seg->type == AS_SEQUENCE)
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leftmost = seg->as[0];
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return leftmost;
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}
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/* Return 1 if there are any 4-byte ASes in the path */
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unsigned int
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aspath_has_as4 (struct aspath *aspath)
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@ -1569,46 +1582,50 @@ aspath_filter_exclude (struct aspath * source, struct aspath * exclude_list)
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/* Add specified AS to the leftmost of aspath. */
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static struct aspath *
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aspath_add_one_as (struct aspath *aspath, as_t asno, u_char type)
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aspath_add_asns (struct aspath *aspath, as_t asno, u_char type, unsigned num)
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{
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struct assegment *assegment = aspath->segments;
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unsigned i;
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/* In case of empty aspath. */
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if (assegment == NULL || assegment->length == 0)
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if (assegment && assegment->type == type)
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{
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aspath->segments = assegment_new (type, 1);
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aspath->segments->as[0] = asno;
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if (assegment)
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assegment_free (assegment);
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return aspath;
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/* extend existing segment */
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aspath->segments = assegment_prepend_asns (aspath->segments, asno, num);
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}
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if (assegment->type == type)
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aspath->segments = assegment_prepend_asns (aspath->segments, asno, 1);
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else
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{
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/* create new segment
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* push it onto head of aspath's segment chain
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*/
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struct assegment *newsegment;
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newsegment = assegment_new (type, 1);
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newsegment->as[0] = asno;
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/* prepend with new segment */
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struct assegment *newsegment = assegment_new (type, num);
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for (i = 0; i < num; i++)
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newsegment->as[i] = asno;
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/* insert potentially replacing empty segment */
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if (assegment && assegment->length == 0)
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{
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newsegment->next = assegment->next;
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assegment_free (assegment);
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}
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else
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newsegment->next = assegment;
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aspath->segments = newsegment;
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}
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aspath_str_update (aspath);
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return aspath;
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}
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/* Add specified AS to the leftmost of aspath num times. */
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struct aspath *
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aspath_add_seq_n (struct aspath *aspath, as_t asno, unsigned num)
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{
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return aspath_add_asns (aspath, asno, AS_SEQUENCE, num);
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}
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/* Add specified AS to the leftmost of aspath. */
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struct aspath *
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aspath_add_seq (struct aspath *aspath, as_t asno)
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{
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return aspath_add_one_as (aspath, asno, AS_SEQUENCE);
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return aspath_add_asns (aspath, asno, AS_SEQUENCE, 1);
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}
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/* Compare leftmost AS value for MED check. If as1's leftmost AS and
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@ -1831,7 +1848,7 @@ aspath_delete_confed_seq (struct aspath *aspath)
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struct aspath*
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aspath_add_confed_seq (struct aspath *aspath, as_t asno)
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{
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return aspath_add_one_as (aspath, asno, AS_CONFED_SEQUENCE);
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return aspath_add_asns (aspath, asno, AS_CONFED_SEQUENCE, 1);
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}
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/* Add new as value to as path structure. */
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@ -84,6 +84,7 @@ extern struct aspath *aspath_dup (struct aspath *);
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extern struct aspath *aspath_aggregate (struct aspath *, struct aspath *);
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extern struct aspath *aspath_prepend (struct aspath *, struct aspath *);
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extern struct aspath *aspath_filter_exclude (struct aspath *, struct aspath *);
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extern struct aspath *aspath_add_seq_n (struct aspath *, as_t, unsigned);
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extern struct aspath *aspath_add_seq (struct aspath *, as_t);
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extern struct aspath *aspath_add_confed_seq (struct aspath *, as_t);
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extern int aspath_cmp (const void *, const void *);
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@ -115,6 +116,7 @@ extern unsigned int aspath_count_hops (const struct aspath *);
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extern unsigned int aspath_count_confeds (struct aspath *);
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extern unsigned int aspath_size (struct aspath *);
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extern as_t aspath_highest (struct aspath *);
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extern as_t aspath_leftmost (struct aspath *);
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extern size_t aspath_put (struct stream *, struct aspath *, int);
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extern struct aspath *aspath_reconcile_as4 (struct aspath *, struct aspath *);
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@ -1435,7 +1435,6 @@ route_set_aspath_prepend (void *rule, struct prefix *prefix, route_map_object_t
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if (type == RMAP_BGP)
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{
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aspath = rule;
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binfo = object;
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if (binfo->attr->aspath->refcnt)
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@ -1443,20 +1442,50 @@ route_set_aspath_prepend (void *rule, struct prefix *prefix, route_map_object_t
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else
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new = binfo->attr->aspath;
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if ((uintptr_t)rule > 10)
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{
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aspath = rule;
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aspath_prepend (aspath, new);
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}
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else
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{
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as_t as = aspath_leftmost(new);
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if (!as) as = binfo->peer->as;
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new = aspath_add_seq_n (new, as, (uintptr_t) rule);
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}
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binfo->attr->aspath = new;
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}
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return RMAP_OKAY;
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}
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static void *
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route_set_aspath_prepend_compile (const char *arg)
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{
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unsigned int num;
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if (sscanf(arg, "last-as %u", &num) == 1 && num > 0 && num < 10)
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return (void*)(uintptr_t)num;
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return route_aspath_compile(arg);
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}
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static void
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route_set_aspath_prepend_free (void *rule)
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{
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if ((uintptr_t)rule > 10)
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route_aspath_free(rule);
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}
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/* Set as-path prepend rule structure. */
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struct route_map_rule_cmd route_set_aspath_prepend_cmd =
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{
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"as-path prepend",
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route_set_aspath_prepend,
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route_aspath_compile,
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route_aspath_free,
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route_set_aspath_prepend_compile,
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route_set_aspath_prepend_free,
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};
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/* `set as-path exclude ASn' */
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@ -3803,6 +3832,15 @@ DEFUN (set_aspath_prepend,
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return ret;
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}
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ALIAS (set_aspath_prepend,
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set_aspath_prepend_lastas_cmd,
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"set as-path prepend (last-as) <1-10>",
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SET_STR
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"Transform BGP AS_PATH attribute\n"
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"Prepend to the as-path\n"
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"Use the peer's AS-number\n"
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"Number of times to insert");
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DEFUN (no_set_aspath_prepend,
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no_set_aspath_prepend_cmd,
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"no set as-path prepend",
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@ -4681,6 +4719,7 @@ bgp_route_map_init (void)
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install_element (RMAP_NODE, &no_set_metric_cmd);
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install_element (RMAP_NODE, &no_set_metric_val_cmd);
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install_element (RMAP_NODE, &set_aspath_prepend_cmd);
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install_element (RMAP_NODE, &set_aspath_prepend_lastas_cmd);
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install_element (RMAP_NODE, &set_aspath_exclude_cmd);
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install_element (RMAP_NODE, &no_set_aspath_prepend_cmd);
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install_element (RMAP_NODE, &no_set_aspath_prepend_val_cmd);
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