Don't import/export MED and LOCAL_PREF on external links.
Added real comparison of BGP routes (inspired by the Cisco one). Default local preference and default MED are now settable. Defined filter keywords for all BGP attributes we know.
This commit is contained in:
Martin Mares
parent
3bbc4ad6ad
commit
56a2bed46b
4 changed files with 88 additions and 51 deletions
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@ -33,5 +33,4 @@ struct adata *int_set_add(struct linpool *pool, struct adata *list, u32 val);
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int int_set_contains(struct adata *list, u32 val);
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struct adata *int_set_del(struct linpool *pool, struct adata *list, u32 val);
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#endif
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@ -29,6 +29,7 @@ struct attr_desc {
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int expected_length;
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int expected_flags;
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int type;
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int allow_in_ebgp;
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int (*validate)(struct bgp_proto *p, byte *attr, int len);
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void (*format)(eattr *ea, byte *buf);
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};
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@ -78,32 +79,24 @@ bgp_check_next_hop(struct bgp_proto *p, byte *a, int len)
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return 8;
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}
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static int
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bgp_check_local_pref(struct bgp_proto *p, byte *a, int len)
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{
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if (!p->is_internal) /* Ignore local preference from EBGP connections */
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return -1;
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return 0;
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}
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static struct attr_desc bgp_attr_table[] = {
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{ NULL, -1, 0, 0, /* Undefined */
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{ NULL, -1, 0, 0, 0, /* Undefined */
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NULL, NULL },
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{ "origin", 1, BAF_TRANSITIVE, EAF_TYPE_INT, /* BA_ORIGIN */
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{ "origin", 1, BAF_TRANSITIVE, EAF_TYPE_INT, 1, /* BA_ORIGIN */
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bgp_check_origin, bgp_format_origin },
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{ "as_path", -1, BAF_TRANSITIVE, EAF_TYPE_AS_PATH, /* BA_AS_PATH */
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{ "as_path", -1, BAF_TRANSITIVE, EAF_TYPE_AS_PATH, 1, /* BA_AS_PATH */
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bgp_check_path, NULL },
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{ "next_hop", 4, BAF_TRANSITIVE, EAF_TYPE_IP_ADDRESS, /* BA_NEXT_HOP */
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{ "next_hop", 4, BAF_TRANSITIVE, EAF_TYPE_IP_ADDRESS, 1, /* BA_NEXT_HOP */
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bgp_check_next_hop, NULL },
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{ "MED", 4, BAF_OPTIONAL, EAF_TYPE_INT, /* BA_MULTI_EXIT_DISC */
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{ "MED", 4, BAF_OPTIONAL, EAF_TYPE_INT, 0, /* BA_MULTI_EXIT_DISC */
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NULL, NULL },
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{ "local_pref", 4, BAF_OPTIONAL, EAF_TYPE_INT, /* BA_LOCAL_PREF */
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bgp_check_local_pref, NULL },
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{ "atomic_aggr", 0, BAF_OPTIONAL, EAF_TYPE_OPAQUE, /* BA_ATOMIC_AGGR */
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{ "local_pref", 4, BAF_OPTIONAL, EAF_TYPE_INT, 0, /* BA_LOCAL_PREF */
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NULL, NULL },
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{ "aggregator", 6, BAF_OPTIONAL, EAF_TYPE_OPAQUE, /* BA_AGGREGATOR */
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{ "atomic_aggr", 0, BAF_OPTIONAL, EAF_TYPE_OPAQUE, 1, /* BA_ATOMIC_AGGR */
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NULL, NULL },
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{ "community", -1, BAF_OPTIONAL | BAF_TRANSITIVE, EAF_TYPE_INT_SET, /* BA_COMMUNITY */
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{ "aggregator", 6, BAF_OPTIONAL, EAF_TYPE_OPAQUE, 1, /* BA_AGGREGATOR */
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NULL, NULL },
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{ "community", -1, BAF_OPTIONAL | BAF_TRANSITIVE, EAF_TYPE_INT_SET, 1, /* BA_COMMUNITY */
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NULL, NULL },
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#if 0
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{ 0, 0 }, /* BA_ORIGINATOR_ID */
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@ -308,10 +301,9 @@ static struct bgp_bucket *
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bgp_get_bucket(struct bgp_proto *p, ea_list *old, ea_list *tmp, int originate)
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{
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ea_list *t, *new;
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unsigned i, cnt;
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unsigned i, cnt, hash, code;
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eattr *a, *d;
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u32 seen = 0;
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unsigned hash;
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struct bgp_bucket *b;
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/* Merge the attribute lists */
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@ -339,8 +331,14 @@ bgp_get_bucket(struct bgp_proto *p, ea_list *old, ea_list *tmp, int originate)
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#endif
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if (EA_PROTO(a->id) != EAP_BGP)
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continue;
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if (EA_ID(a->id) < 32)
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seen |= 1 << EA_ID(a->id);
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code = EA_ID(a->id);
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if (code < ARRAY_SIZE(bgp_attr_table))
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{
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if (!bgp_attr_table[code].allow_in_ebgp && !p->is_internal)
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continue;
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}
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if (code < 32)
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seen |= 1 << code;
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*d = *a;
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if ((d->type & EAF_ORIGINATED) && !originate && (d->flags & BAF_TRANSITIVE) && (d->flags & BAF_OPTIONAL))
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d->flags |= BAF_PARTIAL;
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@ -562,20 +560,53 @@ bgp_rte_better(rte *new, rte *old)
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{
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struct bgp_proto *new_bgp = (struct bgp_proto *) new->attrs->proto;
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struct bgp_proto *old_bgp = (struct bgp_proto *) old->attrs->proto;
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eattr *new_lpref = ea_find(new->attrs->eattrs, EA_CODE(EAP_BGP, BA_LOCAL_PREF));
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eattr *old_lpref = ea_find(old->attrs->eattrs, EA_CODE(EAP_BGP, BA_LOCAL_PREF));
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eattr *x, *y;
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u32 n, o;
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/* Start with local preferences */
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if (new_lpref && old_lpref) /* Somebody might have undefined them */
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x = ea_find(new->attrs->eattrs, EA_CODE(EAP_BGP, BA_LOCAL_PREF));
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y = ea_find(old->attrs->eattrs, EA_CODE(EAP_BGP, BA_LOCAL_PREF));
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n = x ? x->u.data : new_bgp->cf->default_local_pref;
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o = y ? y->u.data : old_bgp->cf->default_local_pref;
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if (n > o)
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return 1;
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if (n < o)
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return 0;
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/* Use AS path lengths */
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if (new_bgp->cf->compare_path_lengths || old_bgp->cf->compare_path_lengths)
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{
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if (new_lpref->u.data > old_lpref->u.data)
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x = ea_find(new->attrs->eattrs, EA_CODE(EAP_BGP, BA_AS_PATH));
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y = ea_find(old->attrs->eattrs, EA_CODE(EAP_BGP, BA_AS_PATH));
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n = x ? as_path_getlen(x->u.ptr) : 100000;
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o = y ? as_path_getlen(y->u.ptr) : 100000;
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if (n < o)
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return 1;
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if (new_lpref->u.data < old_lpref->u.data)
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if (n > o)
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return 0;
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}
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/* Use origins */
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x = ea_find(new->attrs->eattrs, EA_CODE(EAP_BGP, BA_ORIGIN));
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y = ea_find(old->attrs->eattrs, EA_CODE(EAP_BGP, BA_ORIGIN));
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n = x ? x->u.data : 2;
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o = y ? y->u.data : 2;
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if (n < o)
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return 1;
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if (n > o)
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return 0;
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/* Compare MED's */
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x = ea_find(new->attrs->eattrs, EA_CODE(EAP_BGP, BA_MULTI_EXIT_DISC));
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y = ea_find(old->attrs->eattrs, EA_CODE(EAP_BGP, BA_MULTI_EXIT_DISC));
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n = x ? x->u.data : new_bgp->cf->default_med;
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o = y ? y->u.data : old_bgp->cf->default_med;
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if (n < o)
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return 1;
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if (n > o)
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return 0;
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/* A tie breaking procedure according to RFC 1771, section 9.1.2.1 */
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/* FIXME: Look at MULTI_EXIT_DISC, take the lowest */
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/* We don't have interior distances */
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/* We prefer external peers */
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if (new_bgp->is_internal > old_bgp->is_internal)
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@ -586,12 +617,6 @@ bgp_rte_better(rte *new, rte *old)
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return (new_bgp->remote_id < old_bgp->remote_id);
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}
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static int
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bgp_local_pref(struct bgp_proto *p, rta *a)
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{
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return 0; /* FIXME (should be compatible with Cisco defaults?) */
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}
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static int
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bgp_path_loopy(struct bgp_proto *p, eattr *a)
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{
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@ -680,6 +705,8 @@ bgp_decode_attrs(struct bgp_conn *conn, byte *attr, unsigned int len, struct lin
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{ errcode = 5; goto err; }
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if ((desc->expected_flags ^ flags) & (BAF_OPTIONAL | BAF_TRANSITIVE))
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{ errcode = 4; goto err; }
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if (!desc->allow_in_ebgp && !bgp->is_internal)
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continue;
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if (desc->validate)
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{
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errcode = desc->validate(bgp, z, l);
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@ -747,20 +774,6 @@ bgp_decode_attrs(struct bgp_conn *conn, byte *attr, unsigned int len, struct lin
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}
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}
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/* Assign local preference if none defined */
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if (!(seen[BA_LOCAL_PREF/8] & (1 << (BA_LOCAL_PREF%8))))
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{
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ea = lp_alloc(pool, sizeof(ea_list) + sizeof(eattr));
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ea->next = a->eattrs;
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a->eattrs = ea;
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ea->flags = 0;
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ea->count = 1;
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ea->attrs[0].id = EA_CODE(EAP_BGP, BA_LOCAL_PREF);
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ea->attrs[0].flags = BAF_OPTIONAL;
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ea->attrs[0].type = EAF_TYPE_INT;
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ea->attrs[0].u.data = bgp_local_pref(bgp, a);
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}
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/* If the AS path attribute contains our AS, reject the routes */
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e = ea_find(a->eattrs, EA_CODE(EAP_BGP, BA_AS_PATH));
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ASSERT(e);
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@ -21,6 +21,9 @@ struct bgp_config {
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int multihop; /* Number of hops if multihop */
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ip_addr multihop_via; /* Multihop: address to route to */
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int next_hop_self; /* Always set next hop to local IP address */
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int compare_path_lengths; /* Use path lengths when selecting best route */
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u32 default_local_pref; /* Default value for LOCAL_PREF attribute */
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u32 default_med; /* Default value for MULTI_EXIT_DISC attribute */
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unsigned connect_retry_time;
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unsigned hold_time, initial_hold_time;
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unsigned keepalive_time;
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@ -15,7 +15,9 @@ CF_HDR
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CF_DECLS
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CF_KEYWORDS(BGP, LOCAL, NEIGHBOR, AS, HOLD, TIME, CONNECT, RETRY, KEEPALIVE,
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MULTIHOP, STARTUP, VIA, NEXT, HOP, SELF, BGP_PATH)
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MULTIHOP, STARTUP, VIA, NEXT, HOP, SELF, DEFAULT, PATH, METRIC,
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BGP_PATH, BGP_LOCAL_PREF, BGP_MED, BGP_ORIGIN, BGP_NEXT_HOP,
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BGP_ATOMIC_AGGR, BGP_AGGREGATOR, BGP_COMMUNITY)
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CF_GRAMMAR
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@ -27,6 +29,8 @@ bgp_proto_start: proto_start BGP {
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BGP_CFG->hold_time = 240;
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BGP_CFG->connect_retry_time = 120;
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BGP_CFG->initial_hold_time = 240;
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BGP_CFG->default_med = ~0;
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BGP_CFG->compare_path_lengths = 1;
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}
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;
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@ -48,9 +52,27 @@ bgp_proto:
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| bgp_proto KEEPALIVE TIME NUM ';' { BGP_CFG->connect_retry_time = $4; }
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| bgp_proto MULTIHOP NUM VIA IPA ';' { BGP_CFG->multihop = $3; BGP_CFG->multihop_via = $5; }
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| bgp_proto NEXT HOP SELF ';' { BGP_CFG->next_hop_self = 1; }
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| bgp_proto PATH METRIC NUM ';' { BGP_CFG->compare_path_lengths = $4; }
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| bgp_proto DEFAULT BGP_MED NUM ';' { BGP_CFG->default_med = $4; }
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| bgp_proto DEFAULT BGP_LOCAL_PREF NUM ';' { BGP_CFG->default_local_pref = $4; }
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;
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CF_ADDTO(dynamic_attr, BGP_PATH { $$ = f_new_dynamic_attr(EAF_TYPE_AS_PATH, T_PATH, EA_CODE(EAP_BGP, BA_AS_PATH)); })
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CF_ADDTO(dynamic_attr, BGP_PATH
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{ $$ = f_new_dynamic_attr(EAF_TYPE_AS_PATH, T_PATH, EA_CODE(EAP_BGP, BA_AS_PATH)); })
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CF_ADDTO(dynamic_attr, BGP_LOCAL_PREF
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{ $$ = f_new_dynamic_attr(EAF_TYPE_INT, T_INT, EA_CODE(EAP_BGP, BA_LOCAL_PREF)); })
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CF_ADDTO(dynamic_attr, BGP_MED
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{ $$ = f_new_dynamic_attr(EAF_TYPE_INT, T_INT, EA_CODE(EAP_BGP, BA_MULTI_EXIT_DISC)); })
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CF_ADDTO(dynamic_attr, BGP_ORIGIN
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{ $$ = f_new_dynamic_attr(EAF_TYPE_INT, T_INT, EA_CODE(EAP_BGP, BA_ORIGIN)); })
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CF_ADDTO(dynamic_attr, BGP_NEXT_HOP
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{ $$ = f_new_dynamic_attr(EAF_TYPE_IP_ADDRESS, T_IP, EA_CODE(EAP_BGP, BA_NEXT_HOP)); })
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CF_ADDTO(dynamic_attr, BGP_ATOMIC_AGGR
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{ $$ = f_new_dynamic_attr(EAF_TYPE_OPAQUE, T_ENUM_EMPTY, EA_CODE(EAP_BGP, BA_ATOMIC_AGGR)); })
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CF_ADDTO(dynamic_attr, BGP_AGGREGATOR
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{ $$ = f_new_dynamic_attr(EAF_TYPE_INT, T_INT, EA_CODE(EAP_BGP, BA_AGGREGATOR)); })
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CF_ADDTO(dynamic_attr, BGP_COMMUNITY
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{ $$ = f_new_dynamic_attr(EAF_TYPE_INT_SET, T_CLIST, EA_CODE(EAP_BGP, BA_COMMUNITY)); })
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CF_CODE
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