diff options
| -rw-r--r-- | proto/bgp/attrs.c | 245 | ||||
| -rw-r--r-- | proto/bgp/bgp.c | 8 | ||||
| -rw-r--r-- | proto/bgp/bgp.h | 4 |
3 files changed, 239 insertions, 18 deletions
diff --git a/proto/bgp/attrs.c b/proto/bgp/attrs.c index 6428193..0fdc3b6 100644 --- a/proto/bgp/attrs.c +++ b/proto/bgp/attrs.c @@ -19,8 +19,194 @@ #include "bgp.h" +void +bgp_rt_notify(struct proto *P, net *n, rte *new, rte *old, ea_list *tmpa) +{ + DBG("BGP: Got route %I/%d\n", n->n.prefix, n->n.pxlen); +} + +static ea_list * +bgp_create_attrs(struct bgp_proto *p, rte *e, ea_list *old, struct linpool *pool) +{ + ea_list *ea = lp_alloc(pool, sizeof(ea_list) + 3*sizeof(eattr)); + eattr *a = ea->attrs; + rta *rta = e->attrs; + + ea->next = old; + ea->flags = EALF_SORTED; + ea->count = 3; + + a->id = EA_CODE(EAP_BGP, BA_ORIGIN); + a->flags = BAF_TRANSITIVE; + a->type = EAF_TYPE_INT; + if (rta->source == RTS_RIP_EXT || rta->source == RTS_OSPF_EXT) + a->u.data = 2; /* Incomplete */ + else + a->u.data = 0; /* IGP */ + + a->id = EA_CODE(EAP_BGP, BA_AS_PATH); + a->flags = BAF_TRANSITIVE; + a->type = EAF_TYPE_AS_PATH; + if (p->is_internal) + { + a->u.ptr = lp_alloc(pool, sizeof(struct adata)); + a->u.ptr->length = 0; + } + else + { + byte *z; + a->u.ptr = lp_alloc(pool, sizeof(struct adata) + 4); + a->u.ptr->length = 4; + z = a->u.ptr->data; + z[0] = 2; /* AS_SEQUENCE */ + z[1] = 1; /* 1 AS */ + put_u16(z+2, p->local_as); + } + + a->id = EA_CODE(EAP_BGP, BA_NEXT_HOP); + a->flags = BAF_TRANSITIVE; + a->type = EAF_TYPE_IP_ADDRESS; + a->u.ptr = lp_alloc(pool, sizeof(struct adata) + sizeof(ip_addr)); + a->u.ptr->length = sizeof(ip_addr); + + /* FIXME: These rules are bogus!!! */ + if (rta->dest == RTD_ROUTER) + *(ip_addr *)a->u.ptr->data = e->attrs->gw; + else + { + /* FIXME: Next hop == self ... how to do that? */ + *(ip_addr *)a->u.ptr->data = IPA_NONE; + } + + return ea; +} + +ea_list * +bgp_path_prepend(struct linpool *pool, eattr *a, ea_list *old, int as) +{ + struct ea_list *e = lp_alloc(pool, sizeof(ea_list) + sizeof(eattr)); + struct adata *olda = a->u.ptr; + struct adata *newa; + + e->next = old; + e->flags = EALF_SORTED; + e->count = 1; + e->attrs[0].id = EA_CODE(EAP_BGP, BA_AS_PATH); + e->attrs[0].flags = BAF_TRANSITIVE; + e->attrs[0].type = EAF_TYPE_AS_PATH; + if (olda->length && olda->data[0] == 2 && olda->data[1] < 255) /* Starting with sequence => just prepend the AS number */ + { + newa = lp_alloc(pool, sizeof(struct adata) + olda->length + 2); + newa->length = olda->length + 2; + newa->data[0] = 2; + newa->data[1] = olda->data[1] + 1; + memcpy(newa->data+4, olda->data+2, olda->length-2); + } + else /* Create new path segment */ + { + newa = lp_alloc(pool, sizeof(struct adata) + olda->length + 4); + newa->length = olda->length + 4; + newa->data[0] = 2; + newa->data[1] = 1; + memcpy(newa->data+4, olda->data, olda->length); + } + put_u16(newa->data+2, as); + e->attrs[0].u.ptr = newa; + return e; +} + +static ea_list * +bgp_update_attrs(struct bgp_proto *p, rte *e, ea_list *old, struct linpool *pool) +{ + if (!p->is_internal) + old = bgp_path_prepend(pool, ea_find(e->attrs->eattrs, EA_CODE(EAP_BGP, BA_AS_PATH)), old, p->local_as); + + /* FIXME: Set NEXT_HOP to self */ + + return old; +} + +int +bgp_import_control(struct proto *P, rte **new, ea_list **attrs, struct linpool *pool) +{ + rte *e = *new; + struct bgp_proto *p = (struct bgp_proto *) P; + struct bgp_proto *new_bgp = (e->attrs->proto->proto == &proto_bgp) ? (struct bgp_proto *) e->attrs->proto : NULL; + + if (e->attrs->dest != RTD_ROUTER) /* FIXME: This is a debugging kludge, remove some day */ + return -1; + if (new_bgp) + { + if (p->local_as == new_bgp->local_as && p->is_internal && new_bgp->is_internal) + return -1; /* Don't redistribute internal routes with IBGP */ + *attrs = bgp_update_attrs(p, e, *attrs, pool); + } + else + *attrs = bgp_create_attrs(p, e, *attrs, pool); + if (p == new_bgp) /* FIXME: Use a more realistic check based on the NEXT_HOP attribute */ + return 1; + return 0; /* Leave the decision to the filter */ +} + +int +bgp_rte_better(rte *new, rte *old) +{ + struct bgp_proto *new_bgp = (struct bgp_proto *) new->attrs->proto; + struct bgp_proto *old_bgp = (struct bgp_proto *) old->attrs->proto; + eattr *new_lpref = ea_find(new->attrs->eattrs, EA_CODE(EAP_BGP, BA_LOCAL_PREF)); + eattr *old_lpref = ea_find(old->attrs->eattrs, EA_CODE(EAP_BGP, BA_LOCAL_PREF)); + + /* Start with local preferences */ + if (new_lpref && old_lpref) /* Somebody might have undefined them */ + { + if (new_lpref->u.data > old_lpref->u.data) + return 1; + if (new_lpref->u.data < old_lpref->u.data) + return 0; + } + + /* A tie breaking procedure according to RFC 1771, section 9.1.2.1 */ + /* FIXME: Look at MULTI_EXIT_DISC, take the lowest */ + /* We don't have interior distances */ + /* We prefer external peers */ + if (new_bgp->is_internal > old_bgp->is_internal) + return 0; + if (new_bgp->is_internal < old_bgp->is_internal) + return 1; + /* Finally we compare BGP identifiers */ + return (new_bgp->remote_id < old_bgp->remote_id); +} + static int -bgp_check_origin(byte *a, int len) +bgp_local_pref(struct bgp_proto *p, rta *a) +{ + return 0; /* FIXME (should be compatible with Cisco defaults?) */ +} + +static int +bgp_path_loopy(struct bgp_proto *p, eattr *a) +{ + byte *path = a->u.ptr->data; + int len = a->u.ptr->length; + int i, n; + + while (len > 0) + { + n = path[1]; + len -= 2 - 2*n; + path += 2; + for(i=0; i<n; i++) + { + if (get_u16(path) == p->local_as) + return 1; + path += 2; + } + } + return 0; +} + +static int +bgp_check_origin(struct bgp_proto *p, byte *a, int len) { if (len > 2) return 6; @@ -28,7 +214,7 @@ bgp_check_origin(byte *a, int len) } static void -bgp_format_origin(struct eattr *a, byte *buf) +bgp_format_origin(eattr *a, byte *buf) { static char *bgp_origin_names[] = { "IGP", "EGP", "Incomplete" }; @@ -36,7 +222,7 @@ bgp_format_origin(struct eattr *a, byte *buf) } static int -bgp_check_path(byte *a, int len) +bgp_check_path(struct bgp_proto *p, byte *a, int len) { while (len) { @@ -52,7 +238,7 @@ bgp_check_path(byte *a, int len) } static int -bgp_check_next_hop(byte *a, int len) +bgp_check_next_hop(struct bgp_proto *p, byte *a, int len) { ip_addr addr; @@ -63,13 +249,21 @@ bgp_check_next_hop(byte *a, int len) return 8; } +static int +bgp_check_local_pref(struct bgp_proto *p, byte *a, int len) +{ + if (!p->is_internal) /* Ignore local preference from EBGP connections */ + return -1; + return 0; +} + struct attr_desc { char *name; /* FIXME: Use the same names as in filters */ int expected_length; int expected_flags; int type; - int (*validate)(byte *attr, int len); - void (*format)(struct eattr *ea, byte *buf); + int (*validate)(struct bgp_proto *p, byte *attr, int len); + void (*format)(eattr *ea, byte *buf); }; static struct attr_desc bgp_attr_table[] = { @@ -84,7 +278,7 @@ static struct attr_desc bgp_attr_table[] = { { "MED", 4, BAF_OPTIONAL, EAF_TYPE_INT, /* BA_MULTI_EXIT_DISC */ NULL, NULL }, { "local_pref", 4, BAF_OPTIONAL, EAF_TYPE_INT, /* BA_LOCAL_PREF */ - NULL, NULL }, + bgp_check_local_pref, NULL }, { "atomic_aggr", 0, BAF_OPTIONAL, EAF_TYPE_OPAQUE, /* BA_ATOMIC_AGGR */ NULL, NULL }, { "aggregator", 6, BAF_OPTIONAL, EAF_TYPE_OPAQUE, /* BA_AGGREGATOR */ @@ -104,7 +298,8 @@ bgp_decode_attrs(struct bgp_conn *conn, byte *attr, unsigned int len, struct lin { struct bgp_proto *bgp = conn->bgp; rta *a = lp_alloc(pool, sizeof(struct rta)); - unsigned int flags, code, l, errcode, i, type; + unsigned int flags, code, l, i, type; + int errcode; byte *z, *attr_start; byte seen[256/8]; eattr *e; @@ -157,7 +352,6 @@ bgp_decode_attrs(struct bgp_conn *conn, byte *attr, unsigned int len, struct lin DBG("Attr %02x %02x %d\n", code, flags, l); if (seen[code/8] & (1 << (code%8))) goto malformed; - seen[code/8] |= (1 << (code%8)); if (code && code < sizeof(bgp_attr_table)/sizeof(bgp_attr_table[0])) { struct attr_desc *desc = &bgp_attr_table[code]; @@ -165,8 +359,14 @@ bgp_decode_attrs(struct bgp_conn *conn, byte *attr, unsigned int len, struct lin { errcode = 5; goto err; } if ((desc->expected_flags ^ flags) & (BAF_OPTIONAL | BAF_TRANSITIVE)) { errcode = 4; goto err; } - if (desc->validate && (errcode = desc->validate(z, l))) - goto err; + if (desc->validate) + { + errcode = desc->validate(bgp, z, l); + if (errcode > 0) + goto err; + if (errcode < 0) + continue; + } type = desc->type; } else /* Unknown attribute */ @@ -175,7 +375,8 @@ bgp_decode_attrs(struct bgp_conn *conn, byte *attr, unsigned int len, struct lin { errcode = 2; goto err; } type = EAF_TYPE_OPAQUE; } - ea = lp_alloc(pool, sizeof(struct ea_list) + sizeof(struct eattr)); + seen[code/8] |= (1 << (code%8)); + ea = lp_alloc(pool, sizeof(ea_list) + sizeof(eattr)); ea->next = a->eattrs; a->eattrs = ea; ea->flags = 0; @@ -218,6 +419,26 @@ bgp_decode_attrs(struct bgp_conn *conn, byte *attr, unsigned int len, struct lin } } + /* Assign local preference if none defined */ + if (!(seen[BA_LOCAL_PREF/8] & (1 << (BA_LOCAL_PREF%8)))) + { + ea = lp_alloc(pool, sizeof(ea_list) + sizeof(eattr)); + ea->next = a->eattrs; + a->eattrs = ea; + ea->flags = 0; + ea->count = 1; + ea->attrs[0].id = EA_CODE(EAP_BGP, BA_LOCAL_PREF); + ea->attrs[0].flags = BAF_OPTIONAL; + ea->attrs[0].type = EAF_TYPE_INT; + ea->attrs[0].u.data = bgp_local_pref(bgp, a); + } + + /* If the AS path attribute contains our AS, reject the routes */ + e = ea_find(a->eattrs, EA_CODE(EAP_BGP, BA_AS_PATH)); + ASSERT(e); + if (bgp_path_loopy(bgp, e)) + return NULL; + /* Fill in the remaining rta fields */ e = ea_find(a->eattrs, EA_CODE(EAP_BGP, BA_NEXT_HOP)); ASSERT(e); diff --git a/proto/bgp/bgp.c b/proto/bgp/bgp.c index f325aa3..11729db 100644 --- a/proto/bgp/bgp.c +++ b/proto/bgp/bgp.c @@ -28,12 +28,6 @@ static char *bgp_state_names[] = { "Idle", "Connect", "Active", "OpenSent", "Ope static void bgp_connect(struct bgp_proto *p); static void bgp_setup_sk(struct bgp_proto *p, struct bgp_conn *conn, sock *s); -static void -bgp_rt_notify(struct proto *P, net *n, rte *new, rte *old, ea_list *tmpa) -{ - DBG("BGP: Got route %I/%d\n", n->n.prefix, n->n.pxlen); -} - static struct proto * bgp_init(struct proto_config *C) { @@ -42,6 +36,8 @@ bgp_init(struct proto_config *C) struct bgp_proto *p = (struct bgp_proto *) P; P->rt_notify = bgp_rt_notify; + P->rte_better = bgp_rte_better; + P->import_control = bgp_import_control; p->cf = c; p->local_as = c->local_as; p->remote_as = c->remote_as; diff --git a/proto/bgp/bgp.h b/proto/bgp/bgp.h index 8aaac88..45f7e0b 100644 --- a/proto/bgp/bgp.h +++ b/proto/bgp/bgp.h @@ -69,6 +69,10 @@ void bgp_close_conn(struct bgp_conn *c); struct rta *bgp_decode_attrs(struct bgp_conn *conn, byte *a, unsigned int len, struct linpool *pool); int bgp_get_attr(struct eattr *e, byte *buf); +int bgp_rte_better(struct rte *, struct rte *); +void bgp_rt_notify(struct proto *, struct network *, struct rte *, struct rte *, struct ea_list *); +int bgp_import_control(struct proto *, struct rte **, struct ea_list **, struct linpool *); +struct ea_list *bgp_path_prepend(struct linpool *pool, struct eattr *a, struct ea_list *old, int as); /* packets.c */ |