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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.
*/
#undef LOCAL_DEBUG
#include "nest/bird.h"
#include "nest/iface.h"
#include "nest/protocol.h"
#include "nest/route.h"
#include "nest/attrs.h"
#include "nest/mrtdump.h"
#include "conf/conf.h"
#include "lib/unaligned.h"
#include "lib/socket.h"
#include "nest/cli.h"
#include "bgp.h"
static struct rate_limit rl_rcv_update, rl_snd_update;
/* Table for state -> RFC 6608 FSM error subcodes */
static byte fsm_err_subcode[BS_MAX] = {
[BS_OPENSENT] = 1,
[BS_OPENCONFIRM] = 2,
[BS_ESTABLISHED] = 3
};
/*
* MRT Dump format is not semantically specified.
* We will use these values in appropriate fields:
*
* Local AS, Remote AS - configured AS numbers for given BGP instance.
* Local IP, Remote IP - IP addresses of the TCP connection (0 if no connection)
*
* We dump two kinds of MRT messages: STATE_CHANGE (for BGP state
* changes) and MESSAGE (for received BGP messages).
*
* STATE_CHANGE uses always AS4 variant, but MESSAGE uses AS4 variant
* only when AS4 session is established and even in that case MESSAGE
* does not use AS4 variant for initial OPEN message. This strange
* behavior is here for compatibility with Quagga and Bgpdump,
*/
static byte *
mrt_put_bgp4_hdr(byte *buf, struct bgp_conn *conn, int as4)
{
struct bgp_proto *p = conn->bgp;
if (as4)
{
put_u32(buf+0, p->remote_as);
put_u32(buf+4, p->local_as);
buf+=8;
}
else
{
put_u16(buf+0, (p->remote_as <= 0xFFFF) ? p->remote_as : AS_TRANS);
put_u16(buf+2, (p->local_as <= 0xFFFF) ? p->local_as : AS_TRANS);
buf+=4;
}
put_u16(buf+0, (p->neigh && p->neigh->iface) ? p->neigh->iface->index : 0);
put_u16(buf+2, BGP_AF);
buf+=4;
buf = ipa_put_addr(buf, conn->sk ? conn->sk->daddr : IPA_NONE);
buf = ipa_put_addr(buf, conn->sk ? conn->sk->saddr : IPA_NONE);
return buf;
}
static void
mrt_dump_bgp_packet(struct bgp_conn *conn, byte *pkt, unsigned len)
{
byte buf[BGP_MAX_PACKET_LENGTH + 128];
byte *bp = buf + MRTDUMP_HDR_LENGTH;
int as4 = conn->bgp->as4_session;
bp = mrt_put_bgp4_hdr(bp, conn, as4);
memcpy(bp, pkt, len);
bp += len;
mrt_dump_message(&conn->bgp->p, BGP4MP, as4 ? BGP4MP_MESSAGE_AS4 : BGP4MP_MESSAGE,
buf, bp-buf);
}
static inline u16
convert_state(unsigned state)
{
/* Convert state from our BS_* values to values used in MRTDump */
return (state == BS_CLOSE) ? 1 : state + 1;
}
void
mrt_dump_bgp_state_change(struct bgp_conn *conn, unsigned old, unsigned new)
{
byte buf[128];
byte *bp = buf + MRTDUMP_HDR_LENGTH;
bp = mrt_put_bgp4_hdr(bp, conn, 1);
put_u16(bp+0, convert_state(old));
put_u16(bp+2, convert_state(new));
bp += 4;
mrt_dump_message(&conn->bgp->p, BGP4MP, BGP4MP_STATE_CHANGE_AS4, buf, bp-buf);
}
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;
}
#ifdef IPV6
static byte *
bgp_put_cap_ipv6(struct bgp_conn *conn UNUSED, byte *buf)
{
*buf++ = 1; /* Capability 1: Multiprotocol extensions */
*buf++ = 4; /* Capability data length */
*buf++ = 0; /* We support AF IPv6 */
*buf++ = BGP_AF_IPV6;
*buf++ = 0; /* RFU */
*buf++ = 1; /* and SAFI 1 */
return buf;
}
#else
static byte *
bgp_put_cap_ipv4(struct bgp_conn *conn UNUSED, byte *buf)
{
*buf++ = 1; /* Capability 1: Multiprotocol extensions */
*buf++ = 4; /* Capability data length */
*buf++ = 0; /* We support AF IPv4 */
*buf++ = BGP_AF_IPV4;
*buf++ = 0; /* RFU */
*buf++ = 1; /* and SAFI 1 */
return buf;
}
#endif
static byte *
bgp_put_cap_rr(struct bgp_conn *conn UNUSED, byte *buf)
{
*buf++ = 2; /* Capability 2: Support for route refresh */
*buf++ = 0; /* Capability data length */
return buf;
}
static byte *
bgp_put_cap_as4(struct bgp_conn *conn, byte *buf)
{
*buf++ = 65; /* Capability 65: Support for 4-octet AS number */
*buf++ = 4; /* Capability data length */
put_u32(buf, conn->bgp->local_as);
return buf + 4;
}
static byte *
bgp_create_open(struct bgp_conn *conn, byte *buf)
{
struct bgp_proto *p = conn->bgp;
byte *cap;
int cap_len;
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 < 0xFFFF) ? p->local_as : AS_TRANS);
put_u16(buf+3, p->cf->hold_time);
put_u32(buf+5, p->local_id);
if (conn->start_state == BSS_CONNECT_NOCAP)
{
BGP_TRACE(D_PACKETS, "Skipping capabilities");
buf[9] = 0;
return buf + 10;
}
/* Skipped 3 B for length field and Capabilities parameter header */
cap = buf + 12;
#ifndef IPV6
if (p->cf->advertise_ipv4)
cap = bgp_put_cap_ipv4(conn, cap);
#endif
#ifdef IPV6
cap = bgp_put_cap_ipv6(conn, cap);
#endif
if (p->cf->enable_refresh)
cap = bgp_put_cap_rr(conn, cap);
if (conn->want_as4_support)
cap = bgp_put_cap_as4(conn, cap);
cap_len = cap - buf - 12;
if (cap_len > 0)
{
buf[9] = cap_len + 2; /* Optional params len */
buf[10] = 2; /* Option: Capability list */
buf[11] = cap_len; /* Option length */
return cap;
}
else
{
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 >= (1+sizeof(ip_addr)))
{
struct bgp_prefix *px = SKIP_BACK(struct bgp_prefix, bucket_node, HEAD(buck->prefixes));
DBG("\tDequeued route %F\n", &px->n);
*w++ = px->n.pxlen;
bytes = (px->n.pxlen + 7) / 8;
a = *FPREFIX_IP(&px->n);
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;
}
static void
bgp_flush_prefixes(struct bgp_proto *p, struct bgp_bucket *buck)
{
while (!EMPTY_LIST(buck->prefixes))
{
struct bgp_prefix *px = SKIP_BACK(struct bgp_prefix, bucket_node, HEAD(buck->prefixes));
log(L_ERR "%s: - route %F skipped", p->p.name, &px->n);
rem_node(&px->bucket_node);
fib_delete(&p->prefix_fib, px);
}
}
#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 >= 3072)
{
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(p, w+2, buck->eattrs, 2048);
if (a_size < 0)
{
log(L_ERR "%s: Attribute list too long, skipping corresponding routes", p->p.name);
bgp_flush_prefixes(p, buck);
rem_node(&buck->send_node);
bgp_free_bucket(p, buck);
continue;
}
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_RL(&rl_snd_update, D_PACKETS, "Sending UPDATE");
return w;
}
else
return NULL;
}
#else /* IPv6 version */
static inline int
same_iface(struct bgp_proto *p, ip_addr *ip)
{
neighbor *n = neigh_find(&p->p, ip, 0);
return n && p->neigh && n->iface == p->neigh->iface;
}
static byte *
bgp_create_update(struct bgp_conn *conn, byte *buf)
{
struct bgp_proto *p = conn->bgp;
struct bgp_bucket *buck;
int size, second, rem_stored;
int remains = BGP_MAX_PACKET_LENGTH - BGP_HEADER_LENGTH - 4;
byte *w, *w_stored, *tmp, *tstart;
ip_addr *ipp, ip, ip_ll;
ea_list *ea;
eattr *nh;
put_u16(buf, 0);
w = buf+4;
if ((buck = p->withdraw_bucket) && !EMPTY_LIST(buck->prefixes))
{
DBG("Withdrawn routes:\n");
tmp = bgp_attach_attr_wa(&ea, bgp_linpool, BA_MP_UNREACH_NLRI, remains-8);
*tmp++ = 0;
*tmp++ = BGP_AF_IPV6;
*tmp++ = 1;
ea->attrs[0].u.ptr->length = 3 + bgp_encode_prefixes(p, tmp, buck, remains-11);
size = bgp_encode_attrs(p, w, ea, remains);
ASSERT(size >= 0);
w += size;
remains -= size;
}
if (remains >= 3072)
{
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);
rem_stored = remains;
w_stored = w;
size = bgp_encode_attrs(p, w, buck->eattrs, 2048);
if (size < 0)
{
log(L_ERR "%s: Attribute list too long, skipping corresponding routes", p->p.name);
bgp_flush_prefixes(p, buck);
rem_node(&buck->send_node);
bgp_free_bucket(p, buck);
continue;
}
w += size;
remains -= size;
/* We have two addresses here in NEXT_HOP eattr. Really.
Unless NEXT_HOP was modified by filter */
nh = ea_find(buck->eattrs, EA_CODE(EAP_BGP, BA_NEXT_HOP));
ASSERT(nh);
second = (nh->u.ptr->length == NEXT_HOP_LENGTH);
ipp = (ip_addr *) nh->u.ptr->data;
ip = ipp[0];
ip_ll = IPA_NONE;
if (ipa_equal(ip, p->source_addr))
ip_ll = p->local_link;
else
{
/* If we send a route with 'third party' next hop destinated
* in the same interface, we should also send a link local
* next hop address. We use the received one (stored in the
* other part of BA_NEXT_HOP eattr). If we didn't received
* it (for example it is a static route), we can't use
* 'third party' next hop and we have to use local IP address
* as next hop. Sending original next hop address without
* link local address seems to be a natural way to solve that
* problem, but it is contrary to RFC 2545 and Quagga does not
* accept such routes.
*
* There are two cases, either we have global IP, or
* IPA_NONE if the neighbor is link-local. For IPA_NONE,
* we suppose it is on the same iface, see bgp_update_attrs().
*/
if (ipa_zero(ip) || same_iface(p, &ip))
{
if (second && ipa_nonzero(ipp[1]))
ip_ll = ipp[1];
else
{
switch (p->cf->missing_lladdr)
{
case MLL_SELF:
ip = p->source_addr;
ip_ll = p->local_link;
break;
case MLL_DROP:
log(L_ERR "%s: Missing link-local next hop address, skipping corresponding routes", p->p.name);
w = w_stored;
remains = rem_stored;
bgp_flush_prefixes(p, buck);
rem_node(&buck->send_node);
bgp_free_bucket(p, buck);
continue;
case MLL_IGNORE:
break;
}
}
}
}
tstart = tmp = bgp_attach_attr_wa(&ea, bgp_linpool, BA_MP_REACH_NLRI, remains-8);
*tmp++ = 0;
*tmp++ = BGP_AF_IPV6;
*tmp++ = 1;
if (ipa_has_link_scope(ip))
ip = IPA_NONE;
if (ipa_nonzero(ip_ll))
{
*tmp++ = 32;
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;
size = bgp_encode_attrs(p, w, ea, remains);
ASSERT(size >= 0);
w += size;
break;
}
}
size = w - (buf+4);
put_u16(buf+2, size);
lp_flush(bgp_linpool);
if (size)
{
BGP_TRACE_RL(&rl_snd_update, D_PACKETS, "Sending UPDATE");
return w;
}
else
return NULL;
}
#endif
static byte *
bgp_create_route_refresh(struct bgp_conn *conn, byte *buf)
{
struct bgp_proto *p = conn->bgp;
BGP_TRACE(D_PACKETS, "Sending ROUTE-REFRESH");
*buf++ = 0;
*buf++ = BGP_AF;
*buf++ = 0; /* RFU */
*buf++ = 1; /* and SAFI 1 */
return buf;
}
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))
{
/* We can finally close connection and enter idle state */
bgp_conn_enter_idle_state(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_ROUTE_REFRESH))
{
s &= ~(1 << PKT_ROUTE_REFRESH);
type = PKT_ROUTE_REFRESH;
end = bgp_create_route_refresh(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)
ev_schedule(conn->tx_ev);
}
void
bgp_kick_tx(void *vconn)
{
struct bgp_conn *conn = vconn;
DBG("BGP: kicking TX\n");
while (bgp_fire_tx(conn) > 0)
;
}
void
bgp_tx(sock *sk)
{
struct bgp_conn *conn = sk->data;
DBG("BGP: TX hook\n");
while (bgp_fire_tx(conn) > 0)
;
}
/* Capatibility negotiation as per RFC 2842 */
void
bgp_parse_capabilities(struct bgp_conn *conn, byte *opt, int len)
{
// struct bgp_proto *p = conn->bgp;
int cl;
while (len > 0)
{
if (len < 2 || len < 2 + opt[1])
goto err;
cl = opt[1];
switch (opt[0])
{
case 2: /* Route refresh capability, RFC 2918 */
if (cl != 0)
goto err;
conn->peer_refresh_support = 1;
break;
case 65: /* AS4 capability, RFC 4893 */
if (cl != 4)
goto err;
conn->peer_as4_support = 1;
if (conn->want_as4_support)
conn->advertised_as = get_u32(opt + 2);
break;
/* We can safely ignore all other capabilities */
}
len -= 2 + cl;
opt += 2 + cl;
}
return;
err:
bgp_error(conn, 2, 0, NULL, 0);
return;
}
static int
bgp_parse_options(struct bgp_conn *conn, byte *opt, int len)
{
struct bgp_proto *p = conn->bgp;
int ol;
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
ol = opt[1];
switch (opt[0])
{
case 2:
if (conn->start_state == BSS_CONNECT_NOCAP)
BGP_TRACE(D_PACKETS, "Ignoring received capabilities");
else
bgp_parse_capabilities(conn, opt + 2, ol);
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, ol);
return 0;
}
len -= 2 + ol;
opt += 2 + ol;
}
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;
unsigned hold;
u16 base_as;
u32 id;
/* Check state */
if (conn->state != BS_OPENSENT)
{ bgp_error(conn, 5, fsm_err_subcode[conn->state], NULL, 0); return; }
/* 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 */
conn->advertised_as = base_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)", conn->advertised_as, hold, id);
if (bgp_parse_options(conn, pkt+29, pkt[28]))
return;
if (hold > 0 && hold < 3)
{ bgp_error(conn, 2, 6, pkt+22, 2); return; }
if (!id || id == 0xffffffff || id == p->local_id)
{ bgp_error(conn, 2, 3, pkt+24, -4); return; }
if ((conn->advertised_as != base_as) && (base_as != AS_TRANS))
log(L_WARN "%s: Peer advertised inconsistent AS numbers", p->p.name);
if (conn->advertised_as != p->remote_as)
{
if (conn->peer_as4_support)
{
u32 val = htonl(conn->advertised_as);
bgp_error(conn, 2, 2, (byte *) &val, 4);
}
else
bgp_error(conn, 2, 2, pkt+20, 2);
return;
}
/* Check the other connection */
other = (conn == &p->outgoing_conn) ? &p->incoming_conn : &p->outgoing_conn;
switch (other->state)
{
case BS_IDLE:
case BS_CONNECT:
case BS_ACTIVE:
case BS_OPENSENT:
case BS_CLOSE:
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, 7, 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, 7, NULL, 0);
return;
default:
bug("bgp_rx_open: Unknown state");
}
/* Update our local variables */
conn->hold_time = MIN(hold, p->cf->hold_time);
conn->keepalive_time = p->cf->keepalive_time ? : conn->hold_time / 3;
p->remote_id = id;
p->as4_session = conn->want_as4_support && conn->peer_as4_support;
DBG("BGP: Hold timer set to %d, keepalive to %d, AS to %d, ID to %x, AS4 session to %d\n", conn->hold_time, conn->keepalive_time, p->remote_as, p->remote_id, p->as4_session);
bgp_schedule_packet(conn, PKT_KEEPALIVE);
bgp_start_timer(conn->hold_timer, conn->hold_time);
bgp_conn_enter_openconfirm_state(conn);
}
#define DECODE_PREFIX(pp, ll) do { \
int b = *pp++; \
int q; \
ll--; \
if (b > BITS_PER_IP_ADDRESS) { err=10; goto done; } \
q = (b+7) / 8; \
if (ll < q) { err=1; goto done; } \
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_set_next_hop(struct bgp_proto *p, rta *a)
{
struct eattr *nh = ea_find(a->eattrs, EA_CODE(EAP_BGP, BA_NEXT_HOP));
ip_addr *nexthop = (ip_addr *) nh->u.ptr->data;
#ifdef IPV6
int second = (nh->u.ptr->length == NEXT_HOP_LENGTH) && ipa_nonzero(nexthop[1]);
/* First address should not be link-local, but may be zero in direct mode */
if (ipa_has_link_scope(*nexthop))
*nexthop = IPA_NONE;
#else
int second = 0;
#endif
if (p->cf->gw_mode == GW_DIRECT)
{
neighbor *ng = NULL;
if (ipa_nonzero(*nexthop))
ng = neigh_find(&p->p, nexthop, 0);
else if (second) /* GW_DIRECT -> single_hop -> p->neigh != NULL */
ng = neigh_find2(&p->p, nexthop + 1, p->neigh->iface, 0);
/* Fallback */
if (!ng)
ng = p->neigh;
if (ng->scope == SCOPE_HOST)
return 0;
a->dest = RTD_ROUTER;
a->gw = ng->addr;
a->iface = ng->iface;
a->hostentry = NULL;
a->igp_metric = 0;
}
else /* GW_RECURSIVE */
{
if (ipa_zero(*nexthop))
return 0;
rta_set_recursive_next_hop(p->p.table, a, p->igp_table, nexthop, nexthop + second);
}
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;
net *n;
rta *a0, *a = NULL;
ip_addr prefix;
int pxlen, err = 0;
/* 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, &p->p, NULL);
}
if (!attr_len && !nlri_len) /* shortcut */
return;
a0 = bgp_decode_attrs(conn, attrs, attr_len, bgp_linpool, nlri_len);
if (conn->state != BS_ESTABLISHED) /* fatal error during decoding */
return;
if (a0 && nlri_len && bgp_set_next_hop(p, a0))
a = rta_lookup(a0);
while (nlri_len)
{
DECODE_PREFIX(nlri, nlri_len);
DBG("Add %I/%d\n", prefix, pxlen);
if (a)
{
rte *e = rte_get_temp(rta_clone(a));
e->net = net_get(p->p.table, prefix, pxlen);
e->pflags = 0;
e->u.bgp.suppressed = 0;
rte_update(p->p.table, e->net, &p->p, &p->p, e);
}
else
{
/* Forced withdraw as a result of soft error */
if (n = net_find(p->p.table, prefix, pxlen))
rte_update(p->p.table, n, &p->p, &p->p, NULL);
}
}
done:
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) { err=9; goto done; } \
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_attach_next_hop(rta *a0, byte *x)
{
ip_addr *nh = (ip_addr *) bgp_attach_attr_wa(&a0->eattrs, bgp_linpool, BA_NEXT_HOP, NEXT_HOP_LENGTH);
memcpy(nh, x+1, 16);
ipa_ntoh(nh[0]);
/* We store received link local address in the other part of BA_NEXT_HOP eattr. */
if (*x == 32)
{
memcpy(nh+1, x+17, 16);
ipa_ntoh(nh[1]);
}
else
nh[1] = IPA_NONE;
}
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;
net *n;
rta *a0, *a = NULL;
ip_addr prefix;
int pxlen, err = 0;
p->mp_reach_len = 0;
p->mp_unreach_len = 0;
a0 = bgp_decode_attrs(conn, attrs, attr_len, bgp_linpool, 0);
if (conn->state != BS_ESTABLISHED) /* fatal error during decoding */
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, &p->p, NULL);
}
}
DO_NLRI(mp_reach)
{
/* Create fake NEXT_HOP attribute */
if (len < 1 || (*x != 16 && *x != 32) || len < *x + 2)
{ err = 9; goto done; }
if (a0)
bgp_attach_next_hop(a0, x);
/* Also ignore one reserved byte */
len -= *x + 2;
x += *x + 2;
if (a0 && bgp_set_next_hop(p, a0))
a = rta_lookup(a0);
while (len)
{
DECODE_PREFIX(x, len);
DBG("Add %I/%d\n", prefix, pxlen);
if (a)
{
rte *e = rte_get_temp(rta_clone(a));
e->net = net_get(p->p.table, prefix, pxlen);
e->pflags = 0;
e->u.bgp.suppressed = 0;
rte_update(p->p.table, e->net, &p->p, &p->p, e);
}
else
{
/* Forced withdraw as a result of soft error */
if (n = net_find(p->p.table, prefix, pxlen))
rte_update(p->p.table, n, &p->p, &p->p, NULL);
}
}
}
done:
if (a)
rta_free(a);
if (err) /* Use subcode 9, not err */
bgp_error(conn, 3, 9, NULL, 0);
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_RL(&rl_rcv_update, D_PACKETS, "Got UPDATE");
/* Workaround for some BGP implementations that skip initial KEEPALIVE */
if (conn->state == BS_OPENCONFIRM)
bgp_conn_enter_established_state(conn);
if (conn->state != BS_ESTABLISHED)
{ bgp_error(conn, 5, fsm_err_subcode[conn->state], 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" }, /* [RFC3392] */
{ 2, 8, "No supported AFI/SAFI" }, /* This error msg is nonstandard */
{ 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" }, /* Subcodes are according to [RFC6608] */
{ 5, 1, "Unexpected message in OpenSent state" },
{ 5, 2, "Unexpected message in OpenConfirm state" },
{ 5, 3, "Unexpected message in Established state" },
{ 6, 0, "Cease" }, /* Subcodes are according to [RFC4486] */
{ 6, 1, "Maximum number of prefixes reached" },
{ 6, 2, "Administrative shutdown" },
{ 6, 3, "Peer de-configured" },
{ 6, 4, "Administrative reset" },
{ 6, 5, "Connection rejected" },
{ 6, 6, "Other configuration change" },
{ 6, 7, "Connection collision resolution" },
{ 6, 8, "Out of Resources" }
};
/**
* bgp_error_dsc - return BGP error description
* @code: BGP error code
* @subcode: BGP error subcode
*
* bgp_error_dsc() returns error description for BGP errors
* which might be static string or given temporary buffer.
*/
const char *
bgp_error_dsc(unsigned code, unsigned subcode)
{
static char buff[32];
unsigned i;
for (i=0; i < ARRAY_SIZE(bgp_msg_table); i++)
if (bgp_msg_table[i].major == code && bgp_msg_table[i].minor == subcode)
{
return bgp_msg_table[i].msg;
}
bsprintf(buff, "Unknown error %d.%d", code, subcode);
return buff;
}
void
bgp_log_error(struct bgp_proto *p, u8 class, char *msg, unsigned code, unsigned subcode, byte *data, unsigned len)
{
const byte *name;
byte *t, argbuf[36];
unsigned i;
/* Don't report Cease messages generated by myself */
if (code == 6 && class == BE_BGP_TX)
return;
name = bgp_error_dsc(code, subcode);
t = argbuf;
if (len)
{
*t++ = ':';
*t++ = ' ';
if ((code == 2) && (subcode == 2) && ((len == 2) || (len == 4)))
{
/* Bad peer AS - we would like to print the AS */
t += bsprintf(t, "%d", (len == 2) ? get_u16(data) : get_u32(data));
goto done;
}
if (len > 16)
len = 16;
for (i=0; i<len; i++)
t += bsprintf(t, "%02x", data[i]);
}
done:
*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)
{
struct bgp_proto *p = conn->bgp;
if (len < 21)
{
bgp_error(conn, 1, 2, pkt+16, 2);
return;
}
unsigned code = pkt[19];
unsigned subcode = pkt[20];
int err = (code != 6);
bgp_log_error(p, BE_BGP_RX, "Received", code, subcode, pkt+21, len-21);
bgp_store_error(p, conn, BE_BGP_RX, (code << 16) | subcode);
#ifndef IPV6
if ((code == 2) && ((subcode == 4) || (subcode == 7))
/* Error related to capability:
* 4 - Peer does not support capabilities at all.
* 7 - Peer request some capability. Strange unless it is IPv6 only peer.
*/
&& (p->cf->capabilities == 2)
/* Capabilities are not explicitly enabled or disabled, therefore heuristic is used */
&& (conn->start_state == BSS_CONNECT)
/* Failed connection attempt have used capabilities */
&& (p->cf->remote_as <= 0xFFFF))
/* Not possible with disabled capabilities */
{
/* We try connect without capabilities */
log(L_WARN "%s: Capability related error received, retry with capabilities disabled", p->p.name);
p->start_state = BSS_CONNECT_NOCAP;
err = 0;
}
#endif
bgp_conn_enter_close_state(conn);
bgp_schedule_packet(conn, PKT_SCHEDULE_CLOSE);
if (err)
{
bgp_update_startup_delay(p);
bgp_stop(p, 0);
}
}
static void
bgp_rx_keepalive(struct bgp_conn *conn)
{
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:
bgp_conn_enter_established_state(conn);
break;
case BS_ESTABLISHED:
break;
default:
bgp_error(conn, 5, fsm_err_subcode[conn->state], NULL, 0);
}
}
static void
bgp_rx_route_refresh(struct bgp_conn *conn, byte *pkt, int len)
{
struct bgp_proto *p = conn->bgp;
BGP_TRACE(D_PACKETS, "Got ROUTE-REFRESH");
if (conn->state != BS_ESTABLISHED)
{ bgp_error(conn, 5, fsm_err_subcode[conn->state], NULL, 0); return; }
if (!p->cf->enable_refresh)
{ bgp_error(conn, 1, 3, pkt+18, 1); return; }
if (len != (BGP_HEADER_LENGTH + 4))
{ bgp_error(conn, 1, 2, pkt+16, 2); return; }
/* FIXME - we ignore AFI/SAFI values, as we support
just one value and even an error code for an invalid
request is not defined */
proto_request_feeding(&p->p);
}
/**
* 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)
{
byte type = pkt[18];
DBG("BGP: Got packet %02x (%d bytes)\n", type, len);
if (conn->bgp->p.mrtdump & MD_MESSAGES)
mrt_dump_bgp_packet(conn, pkt, len);
switch (type)
{
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);
case PKT_ROUTE_REFRESH: return bgp_rx_route_refresh(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->state == BS_CLOSE) || (conn->sk != sk))
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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