bird/proto/bgp/packets.c

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/*
* BIRD -- BGP Packet Processing
*
* (c) 2000 Martin Mares <mj@ucw.cz>
*
* Can be freely distributed and used under the terms of the GNU GPL.
*/
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#define LOCAL_DEBUG
#include "nest/bird.h"
#include "nest/iface.h"
#include "nest/protocol.h"
#include "nest/route.h"
#include "conf/conf.h"
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#include "lib/unaligned.h"
#include "lib/socket.h"
#include "bgp.h"
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static byte *
bgp_create_notification(struct bgp_conn *conn, byte *buf)
{
DBG("BGP: Sending notification: code=%d, sub=%d, arg=%d:%d\n", conn->notify_code, conn->notify_subcode, conn->notify_arg, conn->notify_arg_size);
buf[0] = conn->notify_code;
buf[1] = conn->notify_subcode;
switch (conn->notify_arg_size)
{
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case 0: return buf + 1;
case 1: buf[2] = conn->notify_arg; return buf+3;
case 2: put_u16(buf+2, conn->notify_arg); return buf+4;
case 4: put_u32(buf+2, conn->notify_arg); return buf+6;
default: bug("bgp_create_notification: unknown error code size");
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}
}
static byte *
bgp_create_open(struct bgp_conn *conn, byte *buf)
{
DBG("BGP: Sending open\n");
buf[0] = BGP_VERSION;
put_u16(buf+1, conn->bgp->local_as);
put_u16(buf+3, conn->bgp->cf->hold_time);
put_u32(buf+5, conn->bgp->local_id);
buf[9] = 0; /* No optional parameters */
return buf+10;
}
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static unsigned int
bgp_encode_prefixes(struct bgp_proto *p, byte *w, struct bgp_bucket *buck, unsigned int remains)
{
byte *start = w;
ip_addr a;
int bytes;
while (!EMPTY_LIST(buck->prefixes) && remains >= 5)
{
struct bgp_prefix *px = SKIP_BACK(struct bgp_prefix, bucket_node, HEAD(buck->prefixes));
DBG("\tDequeued route %I/%d\n", px->n.prefix, px->n.pxlen);
*w++ = px->n.pxlen;
bytes = (px->n.pxlen + 7) / 8;
a = px->n.prefix;
ipa_hton(a);
memcpy(w, &a, bytes);
w += bytes;
rem_node(&px->bucket_node);
fib_delete(&p->prefix_fib, px);
}
return w - start;
}
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static byte *
bgp_create_update(struct bgp_conn *conn, byte *buf)
{
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struct bgp_proto *bgp = conn->bgp;
struct bgp_bucket *buck;
int remains = BGP_MAX_PACKET_LENGTH - BGP_HEADER_LENGTH - 4;
byte *w, *wold;
ip_addr ip;
int wd_size = 0;
int r_size = 0;
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DBG("BGP: Sending update\n");
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/* FIXME: Better timing of updates */
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w = buf+2;
if ((buck = bgp->withdraw_bucket) && !EMPTY_LIST(buck->prefixes))
{
DBG("Withdrawn routes:\n");
wd_size = bgp_encode_prefixes(bgp, w, buck, remains);
w += wd_size;
remains -= wd_size;
}
put_u16(buf, wd_size);
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if (remains >= 2048)
{
while ((buck = (struct bgp_bucket *) HEAD(bgp->bucket_queue))->send_node.next)
{
if (EMPTY_LIST(buck->prefixes))
{
DBG("Deleting empty bucket %p\n", buck);
rem_node(&buck->send_node);
bgp_free_bucket(bgp, buck);
continue;
}
DBG("Processing bucket %p\n", buck);
w = bgp_encode_attrs(w, buck);
remains = BGP_MAX_PACKET_LENGTH - BGP_HEADER_LENGTH - (w-buf);
r_size = bgp_encode_prefixes(bgp, w, buck, remains);
w += r_size;
break;
}
}
else
{
put_u16(w, 0);
w += 2;
}
return (wd_size || r_size) ? w : NULL;
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}
static void
bgp_create_header(byte *buf, unsigned int len, unsigned int type)
{
memset(buf, 0xff, 16); /* Marker */
put_u16(buf+16, len);
buf[18] = type;
}
static int
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bgp_fire_tx(struct bgp_conn *conn)
{
unsigned int s = conn->packets_to_send;
sock *sk = conn->sk;
byte *buf = sk->tbuf;
byte *pkt = buf + BGP_HEADER_LENGTH;
byte *end;
int type;
if (s & (1 << PKT_SCHEDULE_CLOSE))
{
bgp_close_conn(conn);
return 0;
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}
if (s & (1 << PKT_NOTIFICATION))
{
s = 1 << PKT_SCHEDULE_CLOSE;
type = PKT_NOTIFICATION;
end = bgp_create_notification(conn, pkt);
}
else if (s & (1 << PKT_KEEPALIVE))
{
s &= ~(1 << PKT_KEEPALIVE);
type = PKT_KEEPALIVE;
end = pkt; /* Keepalives carry no data */
DBG("BGP: Sending keepalive\n");
bgp_start_timer(conn->keepalive_timer, conn->keepalive_time);
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}
else if (s & (1 << PKT_OPEN))
{
s &= ~(1 << PKT_OPEN);
type = PKT_OPEN;
end = bgp_create_open(conn, pkt);
}
else if (s & (1 << PKT_UPDATE))
{
end = bgp_create_update(conn, pkt);
type = PKT_UPDATE;
if (!end)
{
conn->packets_to_send = 0;
return 0;
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}
}
else
return 0;
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conn->packets_to_send = s;
bgp_create_header(buf, end - buf, type);
return sk_send(sk, end - buf);
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}
void
bgp_schedule_packet(struct bgp_conn *conn, int type)
{
DBG("BGP: Scheduling packet type %d\n", type);
conn->packets_to_send |= 1 << type;
if (conn->sk->tpos == conn->sk->tbuf)
while (bgp_fire_tx(conn))
;
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}
void
bgp_tx(sock *sk)
{
struct bgp_conn *conn = sk->data;
DBG("BGP: TX hook\n");
while (bgp_fire_tx(conn))
;
}
static int
bgp_parse_options(struct bgp_conn *conn, byte *opt, int len)
{
while (len > 0)
{
if (len < 2 || len < 2 + opt[1])
{ bgp_error(conn, 2, 0, 0, 0); return 0; }
#ifdef LOCAL_DEBUG
{
int i;
DBG("\tOption %02x:", opt[0]);
for(i=0; i<opt[1]; i++)
DBG(" %02x", opt[2+i]);
DBG("\n");
}
#endif
switch (opt[0])
{
case 2:
/* Defined in draft-ietf-idr-bgp4-cap-neg-06 */
/* We can safely ignore all capabilities */
break;
default:
/*
* BGP specs don't tell us to send which option
* we didn't recognize, but it's common practice
* to do so. Also, capability negotiation with
* Cisco routers doesn't work without that.
*/
bgp_error(conn, 2, 4, opt[0], 1);
return 0;
}
len -= 2 + opt[1];
opt += 2 + opt[1];
}
return 0;
}
static void
bgp_rx_open(struct bgp_conn *conn, byte *pkt, int len)
{
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struct bgp_conn *other;
struct bgp_proto *p = conn->bgp;
struct bgp_config *cf = p->cf;
unsigned as, hold;
u32 id;
/* Check state */
if (conn->state != BS_OPENSENT)
{ bgp_error(conn, 5, 0, conn->state, 0); }
/* Check message contents */
if (len < 29 || len != 29 + pkt[28])
{ bgp_error(conn, 1, 2, len, 2); return; }
if (pkt[19] != BGP_VERSION)
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{ bgp_error(conn, 2, 1, pkt[19], 1); return; } /* RFC 1771 says 16 bits, draft-09 tells to use 8 */
as = get_u16(pkt+20);
hold = get_u16(pkt+22);
id = get_u32(pkt+24);
DBG("BGP: OPEN as=%d hold=%d id=%08x\n", as, hold, id);
if (cf->remote_as && as != p->remote_as)
{ bgp_error(conn, 2, 2, as, 0); return; }
if (hold > 0 && hold < 3)
{ bgp_error(conn, 2, 6, hold, 0); return; }
p->remote_id = id;
if (bgp_parse_options(conn, pkt+29, pkt[28]))
return;
if (!id || id == 0xffffffff || id == p->local_id)
{ bgp_error(conn, 2, 3, id, 0); return; }
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/* Check the other connection */
other = (conn == &p->outgoing_conn) ? &p->incoming_conn : &p->outgoing_conn;
switch (other->state)
{
case BS_IDLE:
break;
case BS_CONNECT:
case BS_ACTIVE:
case BS_OPENSENT:
DBG("BGP: Collision, closing the other connection\n");
bgp_close_conn(other);
break;
case BS_OPENCONFIRM:
if ((p->local_id < id) == (conn == &p->incoming_conn))
{
/* Should close the other connection */
DBG("BGP: Collision, closing the other connection\n");
bgp_error(other, 6, 0, 0, 0);
break;
}
/* Fall thru */
case BS_ESTABLISHED:
/* Should close this connection */
DBG("BGP: Collision, closing this connection\n");
bgp_error(conn, 6, 0, 0, 0);
return;
default:
bug("bgp_rx_open: Unknown state");
}
/* Make this connection primary */
conn->primary = 1;
p->conn = conn;
/* Update our local variables */
if (hold < p->cf->hold_time)
conn->hold_time = hold;
else
conn->hold_time = p->cf->hold_time;
conn->keepalive_time = p->cf->keepalive_time ? : conn->hold_time / 3;
p->remote_as = as;
p->remote_id = id;
DBG("BGP: Hold timer set to %d, keepalive to %d, AS to %d, ID to %x\n", conn->hold_time, conn->keepalive_time, p->remote_as, p->remote_id);
bgp_schedule_packet(conn, PKT_KEEPALIVE);
bgp_start_timer(conn->hold_timer, conn->hold_time);
conn->state = BS_OPENCONFIRM;
}
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#define DECODE_PREFIX(pp, ll) do { \
int b = *pp++; \
int q; \
ll--; \
if (b > BITS_PER_IP_ADDRESS) { bgp_error(conn, 3, 10, b, 0); return; } \
q = (b+7) / 8; \
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if (ll < q) goto malformed; \
memcpy(&prefix, pp, q); \
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pp += q; \
ll -= q; \
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ipa_ntoh(prefix); \
prefix = ipa_and(prefix, ipa_mkmask(b)); \
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pxlen = b; \
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} while (0)
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/* FIXME: Check validity of prefixes */
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static void
bgp_rx_update(struct bgp_conn *conn, byte *pkt, int len)
{
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struct bgp_proto *bgp = conn->bgp;
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byte *withdrawn, *attrs, *nlri;
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ip_addr prefix;
int withdrawn_len, attr_len, nlri_len, pxlen;
net *n;
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rte e;
rta *a0;
rta *a = NULL;
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DBG("BGP: UPDATE\n");
if (conn->state != BS_ESTABLISHED)
{ bgp_error(conn, 5, 0, conn->state, 0); return; }
bgp_start_timer(conn->hold_timer, conn->hold_time);
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/* Find parts of the packet and check sizes */
if (len < 23)
{
bgp_error(conn, 1, 2, len, 2);
return;
}
withdrawn = pkt + 21;
withdrawn_len = get_u16(pkt + 19);
if (withdrawn_len + 23 > len)
goto malformed;
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attrs = withdrawn + withdrawn_len + 2;
attr_len = get_u16(attrs - 2);
if (withdrawn_len + attr_len + 23 > len)
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goto malformed;
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nlri = attrs + attr_len;
nlri_len = len - withdrawn_len - attr_len - 23;
if (!attr_len && nlri_len)
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goto malformed;
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DBG("Sizes: withdrawn=%d, attrs=%d, NLRI=%d\n", withdrawn_len, attr_len, nlri_len);
/* Withdraw routes */
while (withdrawn_len)
{
DECODE_PREFIX(withdrawn, withdrawn_len);
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DBG("Withdraw %I/%d\n", prefix, pxlen);
if (n = net_find(bgp->p.table, prefix, pxlen))
rte_update(bgp->p.table, n, &bgp->p, NULL);
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}
a0 = bgp_decode_attrs(conn, attrs, attr_len, bgp_linpool, nlri_len);
if (a0 && nlri_len)
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{
a = rta_lookup(a0);
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while (nlri_len)
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{
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rte *e;
DECODE_PREFIX(nlri, nlri_len);
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DBG("Add %I/%d\n", prefix, pxlen);
e = rte_get_temp(rta_clone(a));
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n = net_get(bgp->p.table, prefix, pxlen);
e->net = n;
e->pflags = 0;
rte_update(bgp->p.table, n, &bgp->p, e);
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}
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rta_free(a);
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}
lp_flush(bgp_linpool);
return;
malformed:
if (a)
rta_free(a);
bgp_error(conn, 3, 1, len, 0);
}
static void
bgp_rx_notification(struct bgp_conn *conn, byte *pkt, int len)
{
unsigned arg;
if (len < 21)
{
bgp_error(conn, 1, 2, len, 2);
return;
}
switch (len)
{
case 21: arg = 0; break;
case 22: arg = pkt[21]; break;
case 23: arg = get_u16(pkt+21); break;
case 25: arg = get_u32(pkt+23); break;
default: DBG("BGP: NOTIFICATION with too much data\n"); /* FIXME */ arg = 0;
}
DBG("BGP: NOTIFICATION %d.%d %08x\n", pkt[19], pkt[20], arg); /* FIXME: Better reporting */
conn->error_flag = 1;
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if (conn->primary)
proto_notify_state(&conn->bgp->p, PS_STOP);
bgp_schedule_packet(conn, PKT_SCHEDULE_CLOSE);
}
static void
bgp_rx_keepalive(struct bgp_conn *conn, byte *pkt, unsigned len)
{
DBG("BGP: KEEPALIVE\n");
bgp_start_timer(conn->hold_timer, conn->hold_time);
switch (conn->state)
{
case BS_OPENCONFIRM:
DBG("BGP: UP!!!\n");
conn->state = BS_ESTABLISHED;
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bgp_attr_init(conn->bgp);
proto_notify_state(&conn->bgp->p, PS_UP);
break;
case BS_ESTABLISHED:
break;
default:
bgp_error(conn, 5, 0, conn->state, 0);
}
}
static void
bgp_rx_packet(struct bgp_conn *conn, byte *pkt, unsigned len)
{
DBG("BGP: Got packet %02x (%d bytes)\n", pkt[18], len);
switch (pkt[18])
{
case PKT_OPEN: return bgp_rx_open(conn, pkt, len);
case PKT_UPDATE: return bgp_rx_update(conn, pkt, len);
case PKT_NOTIFICATION: return bgp_rx_notification(conn, pkt, len);
case PKT_KEEPALIVE: return bgp_rx_keepalive(conn, pkt, len);
default: bgp_error(conn, 1, 3, pkt[18], 1);
}
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}
int
bgp_rx(sock *sk, int size)
{
struct bgp_conn *conn = sk->data;
byte *pkt_start = sk->rbuf;
byte *end = pkt_start + size;
unsigned i, len;
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DBG("BGP: RX hook: Got %d bytes\n", size);
while (end >= pkt_start + BGP_HEADER_LENGTH)
{
if (conn->error_flag)
{
DBG("BGP: Error, dropping input\n");
return 1;
}
for(i=0; i<16; i++)
if (pkt_start[i] != 0xff)
{
bgp_error(conn, 1, 1, 0, 0);
break;
}
len = get_u16(pkt_start+16);
if (len < BGP_HEADER_LENGTH || len > BGP_MAX_PACKET_LENGTH)
{
bgp_error(conn, 1, 2, len, 2);
break;
}
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if (end < pkt_start + len)
break;
bgp_rx_packet(conn, pkt_start, len);
pkt_start += len;
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}
if (pkt_start != sk->rbuf)
{
memmove(sk->rbuf, pkt_start, end - pkt_start);
sk->rpos = sk->rbuf + (end - pkt_start);
}
return 0;
}