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/*
* BIRD -- BGP Attributes
*
* (c) 2000 Martin Mares <mj@ucw.cz>
*
* Can be freely distributed and used under the terms of the GNU GPL.
*/
#define LOCAL_DEBUG
#include "nest/bird.h"
#include "nest/iface.h"
#include "nest/protocol.h"
#include "nest/route.h"
#include "conf/conf.h"
#include "lib/resource.h"
#include "lib/string.h"
#include "lib/unaligned.h"
#include "bgp.h"
static int
bgp_check_origin(byte *a, int len)
{
if (len > 2)
return 6;
return 0;
}
static void
bgp_format_origin(struct eattr *a, byte *buf)
{
static char *bgp_origin_names[] = { "IGP", "EGP", "Incomplete" };
bsprintf(buf, bgp_origin_names[a->u.data]);
}
static int
bgp_check_path(byte *a, int len)
{
while (len)
{
DBG("Path segment %02x %02x\n", a[0], a[1]);
if (len < 2 ||
a[0] != BGP_PATH_AS_SET && a[0] != BGP_PATH_AS_SEQUENCE ||
2*a[1] + 2 > len)
return 11;
len -= 2*a[1] + 2;
a += 2*a[1] + 2;
}
return 0;
}
static int
bgp_check_next_hop(byte *a, int len)
{
ip_addr addr;
memcpy(&addr, a, len);
if (ipa_classify(ipa_ntoh(addr)) & IADDR_HOST)
return 0;
else
return 8;
}
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);
};
static struct attr_desc bgp_attr_table[] = {
{ NULL, -1, 0, 0, /* Undefined */
NULL, NULL },
{ "origin", 1, BAF_TRANSITIVE, EAF_TYPE_INT, /* BA_ORIGIN */
bgp_check_origin, bgp_format_origin },
{ "as_path", -1, BAF_TRANSITIVE, EAF_TYPE_AS_PATH, /* BA_AS_PATH */
bgp_check_path, NULL },
{ "next_hop", 4, BAF_TRANSITIVE, EAF_TYPE_IP_ADDRESS, /* BA_NEXT_HOP */
bgp_check_next_hop, NULL },
{ "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 },
{ "atomic_aggr", 0, BAF_OPTIONAL, EAF_TYPE_OPAQUE, /* BA_ATOMIC_AGGR */
NULL, NULL },
{ "aggregator", 6, BAF_OPTIONAL, EAF_TYPE_OPAQUE, /* BA_AGGREGATOR */
NULL, NULL },
#if 0
/* FIXME: Handle community lists */
{ 0, 0 }, /* BA_COMMUNITY */
{ 0, 0 }, /* BA_ORIGINATOR_ID */
{ 0, 0 }, /* BA_CLUSTER_LIST */
#endif
};
static int bgp_mandatory_attrs[] = { BA_ORIGIN, BA_AS_PATH, BA_NEXT_HOP };
struct rta *
bgp_decode_attrs(struct bgp_conn *conn, byte *attr, unsigned int len, struct linpool *pool)
{
struct bgp_proto *bgp = conn->bgp;
rta *a = lp_alloc(pool, sizeof(struct rta));
unsigned int flags, code, l, errcode, i, type;
byte *z, *attr_start;
byte seen[256/8];
eattr *e;
ea_list *ea;
struct adata *ad;
neighbor *neigh;
ip_addr nexthop;
a->proto = &bgp->p;
a->source = RTS_BGP;
a->scope = SCOPE_UNIVERSE;
a->cast = RTC_UNICAST;
a->dest = RTD_ROUTER;
a->flags = 0;
a->aflags = 0;
a->from = bgp->cf->remote_ip;
a->eattrs = NULL;
/* Parse the attributes */
bzero(seen, sizeof(seen));
DBG("BGP: Parsing attributes\n");
while (len)
{
if (len < 2)
goto malformed;
attr_start = attr;
flags = *attr++;
code = *attr++;
len -= 2;
if (flags & BAF_EXT_LEN)
{
if (len < 2)
goto malformed;
l = get_u16(attr);
attr += 2;
len -= 2;
}
else
{
if (len < 1)
goto malformed;
l = *attr++;
len--;
}
if (l > len)
goto malformed;
len -= l;
z = attr;
attr += l;
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];
if (desc->expected_length >= 0 && desc->expected_length != (int) l)
{ 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;
type = desc->type;
}
else /* Unknown attribute */
{ /* FIXME: Send partial bit when forwarding */
if (!(flags & BAF_OPTIONAL))
{ errcode = 2; goto err; }
type = EAF_TYPE_OPAQUE;
}
ea = lp_alloc(pool, sizeof(struct ea_list) + sizeof(struct eattr));
ea->next = a->eattrs;
a->eattrs = ea;
ea->flags = 0;
ea->count = 1;
ea->attrs[0].id = EA_CODE(EAP_BGP, code);
ea->attrs[0].flags = flags;
ea->attrs[0].type = type;
if (type & EAF_EMBEDDED)
ad = NULL;
else
{
ad = lp_alloc(pool, sizeof(struct adata) + l);
ea->attrs[0].u.ptr = ad;
ad->length = l;
memcpy(ad->data, z, l);
}
switch (type)
{
case EAF_TYPE_ROUTER_ID:
case EAF_TYPE_INT:
if (l == 1)
ea->attrs[0].u.data = *z;
else
ea->attrs[0].u.data = get_u32(z);
break;
case EAF_TYPE_IP_ADDRESS:
*(ip_addr *)ad->data = ipa_ntoh(*(ip_addr *)ad->data);
break;
}
}
/* Check if all mandatory attributes are present */
for(i=0; i < sizeof(bgp_mandatory_attrs)/sizeof(bgp_mandatory_attrs[0]); i++)
{
code = bgp_mandatory_attrs[i];
if (!(seen[code/8] & (1 << (code%8))))
{
bgp_error(conn, 3, 3, code, 1);
return NULL;
}
}
/* Fill in the remaining rta fields */
e = ea_find(a->eattrs, EA_CODE(EAP_BGP, BA_NEXT_HOP));
ASSERT(e);
nexthop = *(ip_addr *) e->u.ptr->data;
neigh = neigh_find(&bgp->p, &nexthop, 0);
if (!neigh)
{
if (bgp->cf->multihop)
neigh = neigh_find(&bgp->p, &bgp->cf->multihop_via, 0);
else
neigh = neigh_find(&bgp->p, &bgp->cf->remote_ip, 0);
}
if (!neigh || !neigh->iface)
{
DBG("BGP: No route to peer!\n"); /* FIXME */
return NULL;
}
a->gw = neigh->addr;
a->iface = neigh->iface;
return rta_lookup(a);
malformed:
bgp_error(conn, 3, 1, len, 0);
return NULL;
err:
bgp_error(conn, 3, errcode, code, 0); /* FIXME: Return attribute data! */
return NULL;
}
int
bgp_get_attr(eattr *a, byte *buf)
{
unsigned int i = EA_ID(a->id);
struct attr_desc *d;
if (i && i < sizeof(bgp_attr_table)/sizeof(bgp_attr_table[0]))
{
d = &bgp_attr_table[i];
buf += bsprintf(buf, "%s", d->name);
if (d->format)
{
*buf++ = ':';
*buf++ = ' ';
d->format(a, buf);
return GA_FULL;
}
return GA_NAME;
}
bsprintf(buf, "%02x%s", i, (a->flags & BAF_TRANSITIVE) ? "[t]" : "");
return GA_NAME;
}
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