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bird/proto/bgp/packets.c
Martin Mares 54e55169da BGP documented.
2000-06-04 17:06:18 +00:00

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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.
*/
#undef LOCAL_DEBUG
#include "nest/bird.h"
#include "nest/iface.h"
#include "nest/protocol.h"
#include "nest/route.h"
#include "conf/conf.h"
#include "lib/unaligned.h"
#include "lib/socket.h"
#include "bgp.h"
static byte *
bgp_create_notification(struct bgp_conn *conn, byte *buf)
{
struct bgp_proto *p = conn->bgp;
BGP_TRACE(D_PACKETS, "Sending NOTIFICATION(code=%d.%d)", conn->notify_code, conn->notify_subcode);
buf[0] = conn->notify_code;
buf[1] = conn->notify_subcode;
memcpy(buf+2, conn->notify_data, conn->notify_size);
return buf + 2 + conn->notify_size;
}
static byte *
bgp_create_open(struct bgp_conn *conn, byte *buf)
{
struct bgp_proto *p = conn->bgp;
BGP_TRACE(D_PACKETS, "Sending OPEN(ver=%d,as=%d,hold=%d,id=%08x)",
BGP_VERSION, p->local_as, p->cf->hold_time, p->local_id);
buf[0] = BGP_VERSION;
put_u16(buf+1, p->local_as);
put_u16(buf+3, p->cf->hold_time);
put_u32(buf+5, p->local_id);
buf[9] = 0; /* No optional parameters */
return buf+10;
}
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;
remains -= bytes + 1;
rem_node(&px->bucket_node);
fib_delete(&p->prefix_fib, px);
}
return w - start;
}
#ifndef IPV6 /* IPv4 version */
static byte *
bgp_create_update(struct bgp_conn *conn, byte *buf)
{
struct bgp_proto *p = conn->bgp;
struct bgp_bucket *buck;
int remains = BGP_MAX_PACKET_LENGTH - BGP_HEADER_LENGTH - 4;
byte *w;
int wd_size = 0;
int r_size = 0;
int a_size = 0;
w = buf+2;
if ((buck = p->withdraw_bucket) && !EMPTY_LIST(buck->prefixes))
{
DBG("Withdrawn routes:\n");
wd_size = bgp_encode_prefixes(p, w, buck, remains);
w += wd_size;
remains -= wd_size;
}
put_u16(buf, wd_size);
if (remains >= 2048)
{
while ((buck = (struct bgp_bucket *) HEAD(p->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(p, buck);
continue;
}
DBG("Processing bucket %p\n", buck);
a_size = bgp_encode_attrs(w+2, buck->eattrs, 1024);
put_u16(w, a_size);
w += a_size + 2;
r_size = bgp_encode_prefixes(p, w, buck, remains - a_size);
w += r_size;
break;
}
}
if (!a_size) /* Attributes not already encoded */
{
put_u16(w, 0);
w += 2;
}
if (wd_size || r_size)
{
BGP_TRACE(D_PACKETS, "Sending UPDATE");
return w;
}
else
return NULL;
}
#else /* IPv6 version */
static byte *
bgp_create_update(struct bgp_conn *conn, byte *buf)
{
struct bgp_proto *p = conn->bgp;
struct bgp_bucket *buck;
int size, is_ll;
int remains = BGP_MAX_PACKET_LENGTH - BGP_HEADER_LENGTH - 4;
byte *w, *tmp, *tstart;
ip_addr ip, ip_ll;
ea_list *ea;
eattr *nh;
neighbor *n;
put_u16(buf, 0);
w = buf+4;
if ((buck = p->withdraw_bucket) && !EMPTY_LIST(buck->prefixes))
{
DBG("Withdrawn routes:\n");
tmp = bgp_attach_attr(&ea, bgp_linpool, BA_MP_UNREACH_NLRI, remains-8);
*tmp++ = 0;
*tmp++ = BGP_AF_IPV6;
*tmp++ = 1;
ea->attrs[0].u.ptr->length = bgp_encode_prefixes(p, tmp, buck, remains-11);
size = bgp_encode_attrs(w, ea, remains);
w += size;
remains -= size;
}
if (remains >= 2048)
{
while ((buck = (struct bgp_bucket *) HEAD(p->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(p, buck);
continue;
}
DBG("Processing bucket %p\n", buck);
size = bgp_encode_attrs(w, buck->eattrs, 1024);
w += size;
remains -= size;
tstart = tmp = bgp_attach_attr(&ea, bgp_linpool, BA_MP_REACH_NLRI, remains-8);
*tmp++ = 0;
*tmp++ = BGP_AF_IPV6;
*tmp++ = 1;
nh = ea_find(buck->eattrs, EA_CODE(EAP_BGP, BA_NEXT_HOP));
ASSERT(nh);
ip = *(ip_addr *) nh->u.ptr->data;
if (ipa_equal(ip, p->local_addr))
is_ll = 1;
else
{
n = neigh_find(&p->p, &ip, 0);
if (n && n->iface == p->neigh->iface)
is_ll = 1;
else
is_ll = 0;
}
if (is_ll)
{
*tmp++ = 32;
ip_ll = ipa_or(ipa_build(0xfe80,0,0,0), ipa_and(ip, ipa_build(0,0,~0,~0)));
ipa_hton(ip);
memcpy(tmp, &ip, 16);
ipa_hton(ip_ll);
memcpy(tmp+16, &ip_ll, 16);
tmp += 32;
}
else
{
*tmp++ = 16;
ipa_hton(ip);
memcpy(tmp, &ip, 16);
tmp += 16;
}
*tmp++ = 0; /* No SNPA information */
tmp += bgp_encode_prefixes(p, tmp, buck, remains - (8+3+32+1));
ea->attrs[0].u.ptr->length = tmp - tstart;
w += bgp_encode_attrs(w, ea, remains);
break;
}
}
size = w - (buf+4);
put_u16(buf+2, size);
lp_flush(bgp_linpool);
if (size)
{
BGP_TRACE(D_PACKETS, "Sending UPDATE");
return w;
}
else
return NULL;
}
#endif
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;
}
/**
* bgp_fire_tx - transmit packets
* @conn: connection
*
* Whenever the transmit buffers of the underlying TCP connection
* are free and we have any packets queued for sending, the socket functions
* call bgp_fire_tx() which takes care of selecting the highest priority packet
* queued (Notification > Keepalive > Open > Update), assembling its header
* and body and sending it to the connection.
*/
static int
bgp_fire_tx(struct bgp_conn *conn)
{
struct bgp_proto *p = conn->bgp;
unsigned int s = conn->packets_to_send;
sock *sk = conn->sk;
byte *buf, *pkt, *end;
int type;
if (!sk)
{
conn->packets_to_send = 0;
return 0;
}
buf = sk->tbuf;
pkt = buf + BGP_HEADER_LENGTH;
if (s & (1 << PKT_SCHEDULE_CLOSE))
{
bgp_close_conn(conn);
return 0;
}
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 */
BGP_TRACE(D_PACKETS, "Sending KEEPALIVE");
bgp_start_timer(conn->keepalive_timer, conn->keepalive_time);
}
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;
}
}
else
return 0;
conn->packets_to_send = s;
bgp_create_header(buf, end - buf, type);
return sk_send(sk, end - buf);
}
/**
* bgp_schedule_packet - schedule a packet for transmission
* @conn: connection
* @type: packet type
*
* Schedule a packet of type @type to be sent as soon as possible.
*/
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 && conn->sk->tpos == conn->sk->tbuf)
while (bgp_fire_tx(conn))
;
}
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, NULL, 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, opt[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)
{
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, NULL, 0); }
/* Check message contents */
if (len < 29 || len != 29 + pkt[28])
{ bgp_error(conn, 1, 2, pkt+16, 2); return; }
if (pkt[19] != BGP_VERSION)
{ 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);
BGP_TRACE(D_PACKETS, "Got OPEN(as=%d,hold=%d,id=%08x)", as, hold, id);
if (cf->remote_as && as != p->remote_as)
{ bgp_error(conn, 2, 2, pkt+20, -2); return; }
if (hold > 0 && hold < 3)
{ bgp_error(conn, 2, 6, pkt+22, 2); 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, pkt+24, -4); return; }
/* 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:
BGP_TRACE(D_EVENTS, "Connection collision, giving up the other connection");
bgp_close_conn(other);
break;
case BS_OPENCONFIRM:
if ((p->local_id < id) == (conn == &p->incoming_conn))
{
/* Should close the other connection */
BGP_TRACE(D_EVENTS, "Connection collision, giving up the other connection");
bgp_error(other, 6, 0, NULL, 0);
break;
}
/* Fall thru */
case BS_ESTABLISHED:
/* Should close this connection */
BGP_TRACE(D_EVENTS, "Connection collision, giving up this connection");
bgp_error(conn, 6, 0, NULL, 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;
}
#define DECODE_PREFIX(pp, ll) do { \
int b = *pp++; \
int q; \
ll--; \
if (b > BITS_PER_IP_ADDRESS) { err=10; goto bad; } \
q = (b+7) / 8; \
if (ll < q) { err=1; goto bad; } \
memcpy(&prefix, pp, q); \
pp += q; \
ll -= q; \
ipa_ntoh(prefix); \
prefix = ipa_and(prefix, ipa_mkmask(b)); \
pxlen = b; \
} while (0)
static inline int
bgp_get_nexthop(struct bgp_proto *bgp, rta *a)
{
neighbor *neigh;
ip_addr nexthop;
struct eattr *nh = ea_find(a->eattrs, EA_CODE(EAP_BGP, BA_NEXT_HOP));
ASSERT(nh);
nexthop = *(ip_addr *) nh->u.ptr->data;
neigh = neigh_find(&bgp->p, &nexthop, 0);
if (neigh)
{
if (neigh->scope == SCOPE_HOST)
{
DBG("BGP: Loop!\n");
return 0;
}
}
else
neigh = bgp->neigh;
a->gw = neigh->addr;
a->iface = neigh->iface;
return 1;
}
#ifndef IPV6 /* IPv4 version */
static void
bgp_do_rx_update(struct bgp_conn *conn,
byte *withdrawn, int withdrawn_len,
byte *nlri, int nlri_len,
byte *attrs, int attr_len)
{
struct bgp_proto *p = conn->bgp;
rta *a0;
rta *a = NULL;
ip_addr prefix;
net *n;
rte e;
int err = 0, pxlen;
/* Withdraw routes */
while (withdrawn_len)
{
DECODE_PREFIX(withdrawn, withdrawn_len);
DBG("Withdraw %I/%d\n", prefix, pxlen);
if (n = net_find(p->p.table, prefix, pxlen))
rte_update(p->p.table, n, &p->p, NULL);
}
if (!attr_len && !nlri_len) /* shortcut */
return;
a0 = bgp_decode_attrs(conn, attrs, attr_len, bgp_linpool, nlri_len);
if (a0 && nlri_len && bgp_get_nexthop(p, a0))
{
a = rta_lookup(a0);
while (nlri_len)
{
rte *e;
DECODE_PREFIX(nlri, nlri_len);
DBG("Add %I/%d\n", prefix, pxlen);
e = rte_get_temp(rta_clone(a));
n = net_get(p->p.table, prefix, pxlen);
e->net = n;
e->pflags = 0;
rte_update(p->p.table, n, &p->p, e);
}
}
bad:
if (a)
rta_free(a);
if (err)
bgp_error(conn, 3, err, NULL, 0);
return;
}
#else /* IPv6 version */
#define DO_NLRI(name) \
start = x = p->name##_start; \
len = len0 = p->name##_len; \
if (len) \
{ \
if (len < 3) goto bad; \
af = get_u16(x); \
sub = x[2]; \
x += 3; \
len -= 3; \
DBG("\tNLRI AF=%d sub=%d len=%d\n", af, sub, len);\
} \
else \
af = 0; \
if (af == BGP_AF_IPV6)
static void
bgp_do_rx_update(struct bgp_conn *conn,
byte *withdrawn, int withdrawn_len,
byte *nlri, int nlri_len,
byte *attrs, int attr_len)
{
struct bgp_proto *p = conn->bgp;
byte *start, *x;
int len, len0;
unsigned af, sub;
rta *a0;
rta *a = NULL;
ip_addr prefix;
net *n;
rte e;
int err = 0, pxlen;
p->mp_reach_len = 0;
p->mp_unreach_len = 0;
a0 = bgp_decode_attrs(conn, attrs, attr_len, bgp_linpool, 0);
if (!a0)
return;
DO_NLRI(mp_unreach)
{
while (len)
{
DECODE_PREFIX(x, len);
DBG("Withdraw %I/%d\n", prefix, pxlen);
if (n = net_find(p->p.table, prefix, pxlen))
rte_update(p->p.table, n, &p->p, NULL);
}
}
DO_NLRI(mp_reach)
{
int i;
/* Create fake NEXT_HOP attribute */
if (len < 1 || (*x != 16 && *x != 32) || len < *x + 2)
goto bad;
memcpy(bgp_attach_attr(&a0->eattrs, bgp_linpool, BA_NEXT_HOP, 16), x+1, 16);
len -= *x + 1;
x += *x + 1;
/* Ignore SNPA info */
i = *x++;
while (i--)
{
if (len < 1 || len < 1 + *x)
goto bad;
len -= *x + 1;
x += *x + 1;
}
if (bgp_get_nexthop(p, a0))
{
a = rta_lookup(a0);
while (len)
{
rte *e;
DECODE_PREFIX(x, len);
DBG("Add %I/%d\n", prefix, pxlen);
e = rte_get_temp(rta_clone(a));
n = net_get(p->p.table, prefix, pxlen);
e->net = n;
e->pflags = 0;
rte_update(p->p.table, n, &p->p, e);
}
rta_free(a);
}
}
return;
bad:
bgp_error(conn, 3, 9, start, len0);
if (a)
rta_free(a);
return;
}
#endif
static void
bgp_rx_update(struct bgp_conn *conn, byte *pkt, int len)
{
struct bgp_proto *p = conn->bgp;
byte *withdrawn, *attrs, *nlri;
int withdrawn_len, attr_len, nlri_len;
BGP_TRACE(D_PACKETS, "Got UPDATE");
if (conn->state != BS_ESTABLISHED)
{ bgp_error(conn, 5, 0, NULL, 0); return; }
bgp_start_timer(conn->hold_timer, conn->hold_time);
/* Find parts of the packet and check sizes */
if (len < 23)
{
bgp_error(conn, 1, 2, pkt+16, 2);
return;
}
withdrawn = pkt + 21;
withdrawn_len = get_u16(pkt + 19);
if (withdrawn_len + 23 > len)
goto malformed;
attrs = withdrawn + withdrawn_len + 2;
attr_len = get_u16(attrs - 2);
if (withdrawn_len + attr_len + 23 > len)
goto malformed;
nlri = attrs + attr_len;
nlri_len = len - withdrawn_len - attr_len - 23;
if (!attr_len && nlri_len)
goto malformed;
DBG("Sizes: withdrawn=%d, attrs=%d, NLRI=%d\n", withdrawn_len, attr_len, nlri_len);
lp_flush(bgp_linpool);
bgp_do_rx_update(conn, withdrawn, withdrawn_len, nlri, nlri_len, attrs, attr_len);
return;
malformed:
bgp_error(conn, 3, 1, NULL, 0);
}
static struct {
byte major, minor;
byte *msg;
} bgp_msg_table[] = {
{ 1, 0, "Invalid message header" },
{ 1, 1, "Connection not synchronized" },
{ 1, 2, "Bad message length" },
{ 1, 3, "Bad message type" },
{ 2, 0, "Invalid OPEN message" },
{ 2, 1, "Unsupported version number" },
{ 2, 2, "Bad peer AS" },
{ 2, 3, "Bad BGP identifier" },
{ 2, 4, "Unsupported optional parameter" },
{ 2, 5, "Authentication failure" },
{ 2, 6, "Unacceptable hold time" },
{ 2, 7, "Required capability missing" }, /* capability negotiation draft */
{ 3, 0, "Invalid UPDATE message" },
{ 3, 1, "Malformed attribute list" },
{ 3, 2, "Unrecognized well-known attribute" },
{ 3, 3, "Missing mandatory attribute" },
{ 3, 4, "Invalid attribute flags" },
{ 3, 5, "Invalid attribute length" },
{ 3, 6, "Invalid ORIGIN attribute" },
{ 3, 7, "AS routing loop" }, /* Deprecated */
{ 3, 8, "Invalid NEXT_HOP attribute" },
{ 3, 9, "Optional attribute error" },
{ 3, 10, "Invalid network field" },
{ 3, 11, "Malformed AS_PATH" },
{ 4, 0, "Hold timer expired" },
{ 5, 0, "Finite state machine error" },
{ 6, 0, "Cease" }
};
void
bgp_log_error(struct bgp_proto *p, char *msg, unsigned code, unsigned subcode, byte *data, unsigned len)
{
byte *name, namebuf[16];
byte *t, argbuf[36];
unsigned i;
if (code == 6 && !subcode) /* Don't report Cease messages */
return;
bsprintf(namebuf, "%d.%d", code, subcode);
name = namebuf;
for (i=0; i < ARRAY_SIZE(bgp_msg_table); i++)
if (bgp_msg_table[i].major == code && bgp_msg_table[i].minor == subcode)
{
name = bgp_msg_table[i].msg;
break;
}
t = argbuf;
if (len)
{
*t++ = ':';
*t++ = ' ';
if (len > 16)
len = 16;
for (i=0; i<len; i++)
t += bsprintf(t, "%02x", data[i]);
}
*t = 0;
log(L_REMOTE "%s: %s: %s%s", p->p.name, msg, name, argbuf);
}
static void
bgp_rx_notification(struct bgp_conn *conn, byte *pkt, int len)
{
if (len < 21)
{
bgp_error(conn, 1, 2, pkt+16, 2);
return;
}
bgp_log_error(conn->bgp, "Received error notification", pkt[19], pkt[20], pkt+21, len-21);
conn->error_flag = 1;
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)
{
struct bgp_proto *p = conn->bgp;
BGP_TRACE(D_PACKETS, "Got KEEPALIVE");
bgp_start_timer(conn->hold_timer, conn->hold_time);
switch (conn->state)
{
case BS_OPENCONFIRM:
DBG("BGP: UP!!!\n");
conn->state = BS_ESTABLISHED;
bgp_attr_init(conn->bgp);
proto_notify_state(&conn->bgp->p, PS_UP);
break;
case BS_ESTABLISHED:
break;
default:
bgp_error(conn, 5, 0, NULL, 0);
}
}
/**
* bgp_rx_packet - handle a received packet
* @conn: BGP connection
* @pkt: start of the packet
* @len: packet size
*
* bgp_rx_packet() takes a newly received packet and calls the corresponding
* packet handler according to the packet type.
*/
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);
}
}
/**
* bgp_rx - handle received data
* @sk: socket
* @size: amount of data received
*
* bgp_rx() is called by the socket layer whenever new data arrive from
* the underlying TCP connection. It assembles the data fragments to packets,
* checks their headers and framing and passes complete packets to
* bgp_rx_packet().
*/
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;
DBG("BGP: RX hook: Got %d bytes\n", size);
while (end >= pkt_start + BGP_HEADER_LENGTH)
{
if (conn->error_flag)
{
/*
* We still need to remember the erroneous packet, so that
* we can generate error notifications properly. To avoid
* subsequent reads rewriting the buffer, we just reset the
* rx_hook.
*/
DBG("BGP: Error, dropping input\n");
sk->rx_hook = NULL;
return 0;
}
for(i=0; i<16; i++)
if (pkt_start[i] != 0xff)
{
bgp_error(conn, 1, 1, NULL, 0);
break;
}
len = get_u16(pkt_start+16);
if (len < BGP_HEADER_LENGTH || len > BGP_MAX_PACKET_LENGTH)
{
bgp_error(conn, 1, 2, pkt_start+16, 2);
break;
}
if (end < pkt_start + len)
break;
bgp_rx_packet(conn, pkt_start, len);
pkt_start += len;
}
if (pkt_start != sk->rbuf)
{
memmove(sk->rbuf, pkt_start, end - pkt_start);
sk->rpos = sk->rbuf + (end - pkt_start);
}
return 0;
}
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