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bird/proto/bgp/packets.c
Vincent Bernat 714238716e BGP: Add support for BGP hostname capability 
This is an implementation of draft-walton-bgp-hostname-capability-02.
It is implemented since quite some time for FRR and in datacenter, this
gives a nice output to avoid using IP addresses.

It is disabled by default. The hostname is retrieved from uname(2) and
can be overriden with "hostname" option. The domain name is never set
nor displayed.

Minor changes by committer.
2021-02-10 16:53:57 +01:00

3192 lines
76 KiB
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/*
* BIRD -- BGP Packet Processing
*
* (c) 2000 Martin Mares <mj@ucw.cz>
* (c) 2008--2016 Ondrej Zajicek <santiago@crfreenet.org>
* (c) 2008--2016 CZ.NIC z.s.p.o.
*
* Can be freely distributed and used under the terms of the GNU GPL.
*/
#undef LOCAL_DEBUG
#include <stdlib.h>
#include "nest/bird.h"
#include "nest/iface.h"
#include "nest/protocol.h"
#include "nest/route.h"
#include "nest/attrs.h"
#include "proto/mrt/mrt.h"
#include "conf/conf.h"
#include "lib/unaligned.h"
#include "lib/flowspec.h"
#include "lib/socket.h"
#include "nest/cli.h"
#include "bgp.h"
#define BGP_RR_REQUEST 0
#define BGP_RR_BEGIN 1
#define BGP_RR_END 2
#define BGP_NLRI_MAX (4 + 1 + 32)
#define BGP_MPLS_BOS 1 /* Bottom-of-stack bit */
#define BGP_MPLS_MAX 10 /* Max number of labels that 24*n <= 255 */
#define BGP_MPLS_NULL 3 /* Implicit NULL label */
#define BGP_MPLS_MAGIC 0x800000 /* Magic withdraw label value, RFC 3107 3 */
static struct tbf rl_rcv_update = TBF_DEFAULT_LOG_LIMITS;
static struct tbf rl_snd_update = TBF_DEFAULT_LOG_LIMITS;
/* Table for state -> RFC 6608 FSM error subcodes */
static byte fsm_err_subcode[BS_MAX] = {
[BS_OPENSENT] = 1,
[BS_OPENCONFIRM] = 2,
[BS_ESTABLISHED] = 3
};
static struct bgp_channel *
bgp_get_channel(struct bgp_proto *p, u32 afi)
{
uint i;
for (i = 0; i < p->channel_count; i++)
if (p->afi_map[i] == afi)
return p->channel_map[i];
return NULL;
}
static inline void
put_af3(byte *buf, u32 id)
{
put_u16(buf, id >> 16);
buf[2] = id & 0xff;
}
static inline void
put_af4(byte *buf, u32 id)
{
put_u16(buf, id >> 16);
buf[2] = 0;
buf[3] = id & 0xff;
}
static inline u32
get_af3(byte *buf)
{
return (get_u16(buf) << 16) | buf[2];
}
static inline u32
get_af4(byte *buf)
{
return (get_u16(buf) << 16) | buf[3];
}
static void
init_mrt_bgp_data(struct bgp_conn *conn, struct mrt_bgp_data *d)
{
struct bgp_proto *p = conn->bgp;
int p_ok = conn->state >= BS_OPENCONFIRM;
memset(d, 0, sizeof(struct mrt_bgp_data));
d->peer_as = p->remote_as;
d->local_as = p->local_as;
d->index = (p->neigh && p->neigh->iface) ? p->neigh->iface->index : 0;
d->af = ipa_is_ip4(p->remote_ip) ? BGP_AFI_IPV4 : BGP_AFI_IPV6;
d->peer_ip = conn->sk ? conn->sk->daddr : IPA_NONE;
d->local_ip = conn->sk ? conn->sk->saddr : IPA_NONE;
d->as4 = p_ok ? p->as4_session : 0;
}
static uint bgp_find_update_afi(byte *pos, uint len);
static int
bgp_estimate_add_path(struct bgp_proto *p, byte *pkt, uint len)
{
/* No need to estimate it for other messages than UPDATE */
if (pkt[18] != PKT_UPDATE)
return 0;
/* 1 -> no channel, 2 -> all channels, 3 -> some channels */
if (p->summary_add_path_rx < 3)
return p->summary_add_path_rx == 2;
uint afi = bgp_find_update_afi(pkt, len);
struct bgp_channel *c = bgp_get_channel(p, afi);
if (!c)
{
/* Either frame error (if !afi) or unknown AFI/SAFI,
will be reported later in regular parsing */
BGP_TRACE(D_PACKETS, "MRT processing noticed invalid packet");
return 0;
}
return c->add_path_rx;
}
static void
bgp_dump_message(struct bgp_conn *conn, byte *pkt, uint len)
{
struct mrt_bgp_data d;
init_mrt_bgp_data(conn, &d);
d.message = pkt;
d.msg_len = len;
d.add_path = bgp_estimate_add_path(conn->bgp, pkt, len);
mrt_dump_bgp_message(&d);
}
void
bgp_dump_state_change(struct bgp_conn *conn, uint old, uint new)
{
struct mrt_bgp_data d;
init_mrt_bgp_data(conn, &d);
d.old_state = old;
d.new_state = new;
mrt_dump_bgp_state_change(&d);
}
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;
}
/* Capability negotiation as per RFC 5492 */
const struct bgp_af_caps *
bgp_find_af_caps(struct bgp_caps *caps, u32 afi)
{
struct bgp_af_caps *ac;
WALK_AF_CAPS(caps, ac)
if (ac->afi == afi)
return ac;
return NULL;
}
static struct bgp_af_caps *
bgp_get_af_caps(struct bgp_caps **pcaps, u32 afi)
{
struct bgp_caps *caps = *pcaps;
struct bgp_af_caps *ac;
WALK_AF_CAPS(caps, ac)
if (ac->afi == afi)
return ac;
uint n = caps->af_count;
if (uint_is_pow2(n))
*pcaps = caps = mb_realloc(caps, sizeof(struct bgp_caps) +
(2 * n) * sizeof(struct bgp_af_caps));
ac = &caps->af_data[caps->af_count++];
memset(ac, 0, sizeof(struct bgp_af_caps));
ac->afi = afi;
return ac;
}
static int
bgp_af_caps_cmp(const void *X, const void *Y)
{
const struct bgp_af_caps *x = X, *y = Y;
return (x->afi < y->afi) ? -1 : (x->afi > y->afi) ? 1 : 0;
}
void
bgp_prepare_capabilities(struct bgp_conn *conn)
{
struct bgp_proto *p = conn->bgp;
struct bgp_channel *c;
struct bgp_caps *caps;
struct bgp_af_caps *ac;
if (!p->cf->capabilities)
{
/* Just prepare empty local_caps */
conn->local_caps = mb_allocz(p->p.pool, sizeof(struct bgp_caps));
return;
}
/* Prepare bgp_caps structure */
int n = list_length(&p->p.channels);
caps = mb_allocz(p->p.pool, sizeof(struct bgp_caps) + n * sizeof(struct bgp_af_caps));
conn->local_caps = caps;
caps->as4_support = p->cf->enable_as4;
caps->ext_messages = p->cf->enable_extended_messages;
caps->route_refresh = p->cf->enable_refresh;
caps->enhanced_refresh = p->cf->enable_refresh;
if (caps->as4_support)
caps->as4_number = p->public_as;
if (p->cf->gr_mode)
{
caps->gr_aware = 1;
caps->gr_time = p->cf->gr_time;
caps->gr_flags = p->p.gr_recovery ? BGP_GRF_RESTART : 0;
}
if (p->cf->llgr_mode)
caps->llgr_aware = 1;
if (p->cf->enable_hostname && config->hostname)
{
size_t length = strlen(config->hostname);
char *hostname = mb_allocz(p->p.pool, length+1);
memcpy(hostname, config->hostname, length+1);
caps->hostname = hostname;
}
/* Allocate and fill per-AF fields */
WALK_LIST(c, p->p.channels)
{
ac = &caps->af_data[caps->af_count++];
ac->afi = c->afi;
ac->ready = 1;
ac->ext_next_hop = bgp_channel_is_ipv4(c) && c->cf->ext_next_hop;
caps->any_ext_next_hop |= ac->ext_next_hop;
ac->add_path = c->cf->add_path;
caps->any_add_path |= ac->add_path;
if (c->cf->gr_able)
{
ac->gr_able = 1;
if (p->p.gr_recovery)
ac->gr_af_flags |= BGP_GRF_FORWARDING;
}
if (c->cf->llgr_able)
{
ac->llgr_able = 1;
ac->llgr_time = c->cf->llgr_time;
if (p->p.gr_recovery)
ac->llgr_flags |= BGP_LLGRF_FORWARDING;
}
}
/* Sort capability fields by AFI/SAFI */
qsort(caps->af_data, caps->af_count, sizeof(struct bgp_af_caps), bgp_af_caps_cmp);
}
static byte *
bgp_write_capabilities(struct bgp_conn *conn, byte *buf)
{
struct bgp_proto *p = conn->bgp;
struct bgp_caps *caps = conn->local_caps;
struct bgp_af_caps *ac;
byte *buf_head = buf;
byte *data;
/* Create capability list in buffer */
/*
* Note that max length is ~ 22+21*af_count. With max 12 channels that is
* 274. We are limited just by buffer size (4096, minus header), as we support
* extended optional parameres. Therefore, we have enough space for expansion.
*/
WALK_AF_CAPS(caps, ac)
if (ac->ready)
{
*buf++ = 1; /* Capability 1: Multiprotocol extensions */
*buf++ = 4; /* Capability data length */
put_af4(buf, ac->afi);
buf += 4;
}
if (caps->route_refresh)
{
*buf++ = 2; /* Capability 2: Support for route refresh */
*buf++ = 0; /* Capability data length */
}
if (caps->any_ext_next_hop)
{
*buf++ = 5; /* Capability 5: Support for extended next hop */
*buf++ = 0; /* Capability data length, will be fixed later */
data = buf;
WALK_AF_CAPS(caps, ac)
if (ac->ext_next_hop)
{
put_af4(buf, ac->afi);
put_u16(buf+4, BGP_AFI_IPV6);
buf += 6;
}
data[-1] = buf - data;
}
if (caps->ext_messages)
{
*buf++ = 6; /* Capability 6: Support for extended messages */
*buf++ = 0; /* Capability data length */
}
if (caps->gr_aware)
{
*buf++ = 64; /* Capability 64: Support for graceful restart */
*buf++ = 0; /* Capability data length, will be fixed later */
data = buf;
put_u16(buf, caps->gr_time);
buf[0] |= caps->gr_flags;
buf += 2;
WALK_AF_CAPS(caps, ac)
if (ac->gr_able)
{
put_af3(buf, ac->afi);
buf[3] = ac->gr_af_flags;
buf += 4;
}
data[-1] = buf - data;
}
if (caps->as4_support)
{
*buf++ = 65; /* Capability 65: Support for 4-octet AS number */
*buf++ = 4; /* Capability data length */
put_u32(buf, p->public_as);
buf += 4;
}
if (caps->any_add_path)
{
*buf++ = 69; /* Capability 69: Support for ADD-PATH */
*buf++ = 0; /* Capability data length, will be fixed later */
data = buf;
WALK_AF_CAPS(caps, ac)
if (ac->add_path)
{
put_af3(buf, ac->afi);
buf[3] = ac->add_path;
buf += 4;
}
data[-1] = buf - data;
}
if (caps->enhanced_refresh)
{
*buf++ = 70; /* Capability 70: Support for enhanced route refresh */
*buf++ = 0; /* Capability data length */
}
if (caps->llgr_aware)
{
*buf++ = 71; /* Capability 71: Support for long-lived graceful restart */
*buf++ = 0; /* Capability data length, will be fixed later */
data = buf;
WALK_AF_CAPS(caps, ac)
if (ac->llgr_able)
{
put_af3(buf, ac->afi);
buf[3] = ac->llgr_flags;
put_u24(buf+4, ac->llgr_time);
buf += 7;
}
data[-1] = buf - data;
}
if (caps->hostname)
{
*buf++ = 73; /* Capability 73: Hostname */
*buf++ = 0; /* Capability data length */
data = buf;
/* Hostname */
size_t length = strlen(caps->hostname);
*buf++ = length;
memcpy(buf, caps->hostname, length);
buf += length;
/* Domain, not implemented */
*buf++ = 0;
data[-1] = buf - data;
}
caps->length = buf - buf_head;
return buf;
}
static int
bgp_read_capabilities(struct bgp_conn *conn, byte *pos, int len)
{
struct bgp_proto *p = conn->bgp;
struct bgp_caps *caps;
struct bgp_af_caps *ac;
int i, cl;
u32 af;
if (!conn->remote_caps)
caps = mb_allocz(p->p.pool, sizeof(struct bgp_caps) + sizeof(struct bgp_af_caps));
else
{
caps = conn->remote_caps;
conn->remote_caps = NULL;
}
caps->length += len;
while (len > 0)
{
if (len < 2 || len < (2 + pos[1]))
goto err;
/* Capability length */
cl = pos[1];
/* Capability type */
switch (pos[0])
{
case 1: /* Multiprotocol capability, RFC 4760 */
if (cl != 4)
goto err;
af = get_af4(pos+2);
ac = bgp_get_af_caps(&caps, af);
ac->ready = 1;
break;
case 2: /* Route refresh capability, RFC 2918 */
if (cl != 0)
goto err;
caps->route_refresh = 1;
break;
case 5: /* Extended next hop encoding capability, RFC 5549 */
if (cl % 6)
goto err;
for (i = 0; i < cl; i += 6)
{
/* Specified only for IPv4 prefixes with IPv6 next hops */
if ((get_u16(pos+2+i+0) != BGP_AFI_IPV4) ||
(get_u16(pos+2+i+4) != BGP_AFI_IPV6))
continue;
af = get_af4(pos+2+i);
ac = bgp_get_af_caps(&caps, af);
ac->ext_next_hop = 1;
}
break;
case 6: /* Extended message length capability, RFC draft */
if (cl != 0)
goto err;
caps->ext_messages = 1;
break;
case 64: /* Graceful restart capability, RFC 4724 */
if (cl % 4 != 2)
goto err;
/* Only the last instance is valid */
WALK_AF_CAPS(caps, ac)
{
ac->gr_able = 0;
ac->gr_af_flags = 0;
}
caps->gr_aware = 1;
caps->gr_flags = pos[2] & 0xf0;
caps->gr_time = get_u16(pos + 2) & 0x0fff;
for (i = 2; i < cl; i += 4)
{
af = get_af3(pos+2+i);
ac = bgp_get_af_caps(&caps, af);
ac->gr_able = 1;
ac->gr_af_flags = pos[2+i+3];
}
break;
case 65: /* AS4 capability, RFC 6793 */
if (cl != 4)
goto err;
caps->as4_support = 1;
caps->as4_number = get_u32(pos + 2);
break;
case 69: /* ADD-PATH capability, RFC 7911 */
if (cl % 4)
goto err;
for (i = 0; i < cl; i += 4)
{
byte val = pos[2+i+3];
if (!val || (val > BGP_ADD_PATH_FULL))
{
log(L_WARN "%s: Got ADD-PATH capability with unknown value %u, ignoring",
p->p.name, val);
break;
}
}
for (i = 0; i < cl; i += 4)
{
af = get_af3(pos+2+i);
ac = bgp_get_af_caps(&caps, af);
ac->add_path = pos[2+i+3];
}
break;
case 70: /* Enhanced route refresh capability, RFC 7313 */
if (cl != 0)
goto err;
caps->enhanced_refresh = 1;
break;
case 71: /* Long lived graceful restart capability, RFC draft */
if (cl % 7)
goto err;
/* Presumably, only the last instance is valid */
WALK_AF_CAPS(caps, ac)
{
ac->llgr_able = 0;
ac->llgr_flags = 0;
ac->llgr_time = 0;
}
caps->llgr_aware = 1;
for (i = 0; i < cl; i += 7)
{
af = get_af3(pos+2+i);
ac = bgp_get_af_caps(&caps, af);
ac->llgr_able = 1;
ac->llgr_flags = pos[2+i+3];
ac->llgr_time = get_u24(pos + 2+i+4);
}
break;
case 73: /* Hostname, RFC draft */
if ((cl < 2) || (cl < 2 + pos[2]))
goto err;
int length = pos[2];
char *hostname = mb_allocz(p->p.pool, length+1);
memcpy(hostname, pos + 3, length);
hostname[length] = 0;
for (i = 0; i < length; i++)
if (hostname[i] < ' ')
hostname[i] = ' ';
caps->hostname = hostname;
/* We can safely ignore all other capabilities */
}
ADVANCE(pos, len, 2 + cl);
}
/* The LLGR capability must be advertised together with the GR capability,
otherwise it must be disregarded */
if (!caps->gr_aware && caps->llgr_aware)
{
caps->llgr_aware = 0;
WALK_AF_CAPS(caps, ac)
{
ac->llgr_able = 0;
ac->llgr_flags = 0;
ac->llgr_time = 0;
}
}
conn->remote_caps = caps;
return 0;
err:
mb_free(caps);
bgp_error(conn, 2, 0, NULL, 0);
return -1;
}
static int
bgp_check_capabilities(struct bgp_conn *conn)
{
struct bgp_proto *p = conn->bgp;
struct bgp_caps *local = conn->local_caps;
struct bgp_caps *remote = conn->remote_caps;
struct bgp_channel *c;
int count = 0;
/* This is partially overlapping with bgp_conn_enter_established_state(),
but we need to run this just after we receive OPEN message */
WALK_LIST(c, p->p.channels)
{
const struct bgp_af_caps *loc = bgp_find_af_caps(local, c->afi);
const struct bgp_af_caps *rem = bgp_find_af_caps(remote, c->afi);
/* Find out whether this channel will be active */
int active = loc && loc->ready &&
((rem && rem->ready) || (!remote->length && (c->afi == BGP_AF_IPV4)));
/* Mandatory must be active */
if (c->cf->mandatory && !active)
return 0;
if (active)
count++;
}
/* We need at least one channel active */
if (!count)
return 0;
return 1;
}
static int
bgp_read_options(struct bgp_conn *conn, byte *pos, uint len, uint rest)
{
struct bgp_proto *p = conn->bgp;
int ext = 0;
/* Handle extended length (draft-ietf-idr-ext-opt-param-07) */
if ((len > 0) && (rest > 0) && (pos[0] == 255))
{
if (rest < 3)
goto err;
/* Update pos/len to describe optional data */
len = get_u16(pos+1);
ext = 1;
pos += 3;
rest -= 3;
}
/* Verify that optional data fits into OPEN packet */
if (len > rest)
goto err;
/* Length of option parameter header */
uint hlen = ext ? 3 : 2;
while (len > 0)
{
if (len < hlen)
goto err;
uint otype = get_u8(pos);
uint olen = ext ? get_u16(pos+1) : get_u8(pos+1);
if (len < (hlen + olen))
goto err;
if (otype == 2)
{
/* BGP capabilities, RFC 5492 */
if (p->cf->capabilities)
if (bgp_read_capabilities(conn, pos + hlen, olen) < 0)
return -1;
}
else
{
/* Unknown option */
bgp_error(conn, 2, 4, pos, hlen + olen);
return -1;
}
ADVANCE(pos, len, hlen + olen);
}
/* Prepare empty caps if no capability option was announced */
if (!conn->remote_caps)
conn->remote_caps = mb_allocz(p->p.pool, sizeof(struct bgp_caps));
return 0;
err:
bgp_error(conn, 2, 0, NULL, 0);
return -1;
}
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->public_as, p->cf->hold_time, p->local_id);
buf[0] = BGP_VERSION;
put_u16(buf+1, (p->public_as < 0xFFFF) ? p->public_as : AS_TRANS);
put_u16(buf+3, p->cf->hold_time);
put_u32(buf+5, p->local_id);
if (p->cf->capabilities)
{
/* Prepare local_caps and write capabilities to buffer */
byte *pos = buf+12;
byte *end = bgp_write_capabilities(conn, pos);
uint len = end - pos;
if (len < 254)
{
buf[9] = len + 2; /* Optional parameters length */
buf[10] = 2; /* Option 2: Capability list */
buf[11] = len; /* Option data length */
}
else /* draft-ietf-idr-ext-opt-param-07 */
{
/* Move capabilities 4 B forward */
memmove(buf + 16, pos, len);
pos = buf + 16;
end = pos + len;
buf[9] = 255; /* Non-ext OP length, fake */
buf[10] = 255; /* Non-ext OP type, signals extended length */
put_u16(buf+11, len + 3); /* Extended optional parameters length */
buf[13] = 2; /* Option 2: Capability list */
put_u16(buf+14, len); /* Option extended data length */
}
return end;
}
else
{
buf[9] = 0; /* No optional parameters */
return buf + 10;
}
return buf;
}
static void
bgp_rx_open(struct bgp_conn *conn, byte *pkt, uint len)
{
struct bgp_proto *p = conn->bgp;
struct bgp_conn *other;
u32 asn, hold, id;
/* Check state */
if (conn->state != BS_OPENSENT)
{ bgp_error(conn, 5, fsm_err_subcode[conn->state], NULL, 0); return; }
/* Check message length */
if (len < 29)
{ bgp_error(conn, 1, 2, pkt+16, 2); return; }
if (pkt[19] != BGP_VERSION)
{ u16 val = BGP_VERSION; bgp_error(conn, 2, 1, (byte *) &val, 2); return; }
asn = 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=%R)", asn, hold, id);
if (bgp_read_options(conn, pkt+29, pkt[28], len-29) < 0)
return;
if (hold > 0 && hold < 3)
{ bgp_error(conn, 2, 6, pkt+22, 2); return; }
/* RFC 6286 2.2 - router ID is nonzero and AS-wide unique */
if (!id || (p->is_internal && id == p->local_id))
{ bgp_error(conn, 2, 3, pkt+24, -4); return; }
/* RFC 5492 4 - check for required capabilities */
if (p->cf->capabilities && !bgp_check_capabilities(conn))
{ bgp_error(conn, 2, 7, NULL, 0); return; }
struct bgp_caps *caps = conn->remote_caps;
if (caps->as4_support)
{
u32 as4 = caps->as4_number;
if ((as4 != asn) && (asn != AS_TRANS))
log(L_WARN "%s: Peer advertised inconsistent AS numbers", p->p.name);
/* When remote ASN is unspecified, it must be external one */
if (p->remote_as ? (as4 != p->remote_as) : (as4 == p->local_as))
{ as4 = htonl(as4); bgp_error(conn, 2, 2, (byte *) &as4, 4); return; }
conn->received_as = as4;
}
else
{
if (p->remote_as ? (asn != p->remote_as) : (asn == p->local_as))
{ bgp_error(conn, 2, 2, pkt+20, 2); return; }
conn->received_as = asn;
}
/* Check the other connection */
other = (conn == &p->outgoing_conn) ? &p->incoming_conn : &p->outgoing_conn;
switch (other->state)
{
case BS_CONNECT:
case BS_ACTIVE:
/* Stop outgoing connection attempts */
bgp_conn_enter_idle_state(other);
break;
case BS_IDLE:
case BS_OPENSENT:
case BS_CLOSE:
break;
case BS_OPENCONFIRM:
/*
* Description of collision detection rules in RFC 4271 is confusing and
* contradictory, but it is essentially:
*
* 1. Router with higher ID is dominant
* 2. If both have the same ID, router with higher ASN is dominant [RFC6286]
* 3. When both connections are in OpenConfirm state, one initiated by
* the dominant router is kept.
*
* The first line in the expression below evaluates whether the neighbor
* is dominant, the second line whether the new connection was initiated
* by the neighbor. If both are true (or both are false), we keep the new
* connection, otherwise we keep the old one.
*/
if (((p->local_id < id) || ((p->local_id == id) && (p->public_as < p->remote_as)))
== (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;
conn->as4_session = conn->local_caps->as4_support && caps->as4_support;
conn->ext_messages = conn->local_caps->ext_messages && caps->ext_messages;
p->remote_id = id;
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, conn->as4_session);
bgp_schedule_packet(conn, NULL, PKT_KEEPALIVE);
bgp_start_timer(conn->hold_timer, conn->hold_time);
bgp_conn_enter_openconfirm_state(conn);
}
/*
* Next hop handling
*/
#define REPORT(msg, args...) \
({ log(L_REMOTE "%s: " msg, s->proto->p.name, ## args); })
#define DISCARD(msg, args...) \
({ REPORT(msg, ## args); return; })
#define WITHDRAW(msg, args...) \
({ REPORT(msg, ## args); s->err_withdraw = 1; return; })
#define BAD_AFI "Unexpected AF <%u/%u> in UPDATE"
#define BAD_NEXT_HOP "Invalid NEXT_HOP attribute"
#define NO_NEXT_HOP "Missing NEXT_HOP attribute"
#define NO_LABEL_STACK "Missing MPLS stack"
static void
bgp_apply_next_hop(struct bgp_parse_state *s, rta *a, ip_addr gw, ip_addr ll)
{
struct bgp_proto *p = s->proto;
struct bgp_channel *c = s->channel;
if (c->cf->gw_mode == GW_DIRECT)
{
neighbor *nbr = NULL;
/* GW_DIRECT -> single_hop -> p->neigh != NULL */
if (ipa_nonzero(gw))
nbr = neigh_find(&p->p, gw, NULL, 0);
else if (ipa_nonzero(ll))
nbr = neigh_find(&p->p, ll, p->neigh->iface, 0);
if (!nbr || (nbr->scope == SCOPE_HOST))
WITHDRAW(BAD_NEXT_HOP);
a->dest = RTD_UNICAST;
a->nh.gw = nbr->addr;
a->nh.iface = nbr->iface;
a->igp_metric = c->cf->cost;
}
else /* GW_RECURSIVE */
{
if (ipa_zero(gw))
WITHDRAW(BAD_NEXT_HOP);
rtable *tab = ipa_is_ip4(gw) ? c->igp_table_ip4 : c->igp_table_ip6;
s->hostentry = rt_get_hostentry(tab, gw, ll, c->c.table);
if (!s->mpls)
rta_apply_hostentry(a, s->hostentry, NULL);
/* With MPLS, hostentry is applied later in bgp_apply_mpls_labels() */
}
}
static void
bgp_apply_mpls_labels(struct bgp_parse_state *s, rta *a, u32 *labels, uint lnum)
{
if (lnum > MPLS_MAX_LABEL_STACK)
{
REPORT("Too many MPLS labels ($u)", lnum);
a->dest = RTD_UNREACHABLE;
a->hostentry = NULL;
a->nh = (struct nexthop) { };
return;
}
/* Handle implicit NULL as empty MPLS stack */
if ((lnum == 1) && (labels[0] == BGP_MPLS_NULL))
lnum = 0;
if (s->channel->cf->gw_mode == GW_DIRECT)
{
a->nh.labels = lnum;
memcpy(a->nh.label, labels, 4*lnum);
}
else /* GW_RECURSIVE */
{
mpls_label_stack ms;
ms.len = lnum;
memcpy(ms.stack, labels, 4*lnum);
rta_apply_hostentry(a, s->hostentry, &ms);
}
}
static int
bgp_match_src(struct bgp_export_state *s, int mode)
{
switch (mode)
{
case NH_NO: return 0;
case NH_ALL: return 1;
case NH_IBGP: return s->src && s->src->is_internal;
case NH_EBGP: return s->src && !s->src->is_internal;
default: return 0;
}
}
static inline int
bgp_use_next_hop(struct bgp_export_state *s, eattr *a)
{
struct bgp_proto *p = s->proto;
struct bgp_channel *c = s->channel;
ip_addr *nh = (void *) a->u.ptr->data;
/* Handle next hop self option */
if (c->cf->next_hop_self && bgp_match_src(s, c->cf->next_hop_self))
return 0;
/* Handle next hop keep option */
if (c->cf->next_hop_keep && bgp_match_src(s, c->cf->next_hop_keep))
return 1;
/* Keep it when explicitly set in export filter */
if (a->type & EAF_FRESH)
return 1;
/* Check for non-matching AF */
if ((ipa_is_ip4(*nh) != bgp_channel_is_ipv4(c)) && !c->ext_next_hop)
return 0;
/* Keep it when exported to internal peers */
if (p->is_interior && ipa_nonzero(*nh))
return 1;
/* Keep it when forwarded between single-hop BGPs on the same iface */
struct iface *ifa = (s->src && s->src->neigh) ? s->src->neigh->iface : NULL;
return p->neigh && (p->neigh->iface == ifa);
}
static inline int
bgp_use_gateway(struct bgp_export_state *s)
{
struct bgp_proto *p = s->proto;
struct bgp_channel *c = s->channel;
rta *ra = s->route->attrs;
/* Handle next hop self option - also applies to gateway */
if (c->cf->next_hop_self && bgp_match_src(s, c->cf->next_hop_self))
return 0;
/* We need one valid global gateway */
if ((ra->dest != RTD_UNICAST) || ra->nh.next || ipa_zero(ra->nh.gw) || ipa_is_link_local(ra->nh.gw))
return 0;
/* Check for non-matching AF */
if ((ipa_is_ip4(ra->nh.gw) != bgp_channel_is_ipv4(c)) && !c->ext_next_hop)
return 0;
/* Use it when exported to internal peers */
if (p->is_interior)
return 1;
/* Use it when forwarded to single-hop BGP peer on on the same iface */
return p->neigh && (p->neigh->iface == ra->nh.iface);
}
static void
bgp_update_next_hop_ip(struct bgp_export_state *s, eattr *a, ea_list **to)
{
if (!a || !bgp_use_next_hop(s, a))
{
if (bgp_use_gateway(s))
{
rta *ra = s->route->attrs;
ip_addr nh[1] = { ra->nh.gw };
bgp_set_attr_data(to, s->pool, BA_NEXT_HOP, 0, nh, 16);
if (s->mpls)
{
u32 implicit_null = BGP_MPLS_NULL;
u32 *labels = ra->nh.labels ? ra->nh.label : &implicit_null;
uint lnum = ra->nh.labels ? ra->nh.labels : 1;
bgp_set_attr_data(to, s->pool, BA_MPLS_LABEL_STACK, 0, labels, lnum * 4);
}
}
else
{
ip_addr nh[2] = { s->channel->next_hop_addr, s->channel->link_addr };
bgp_set_attr_data(to, s->pool, BA_NEXT_HOP, 0, nh, ipa_nonzero(nh[1]) ? 32 : 16);
s->local_next_hop = 1;
/* TODO: Use local MPLS assigned label */
if (s->mpls)
{
u32 implicit_null = BGP_MPLS_NULL;
bgp_set_attr_data(to, s->pool, BA_MPLS_LABEL_STACK, 0, &implicit_null, 4);
}
}
}
/* Check if next hop is valid */
a = bgp_find_attr(*to, BA_NEXT_HOP);
if (!a)
WITHDRAW(NO_NEXT_HOP);
ip_addr *nh = (void *) a->u.ptr->data;
ip_addr peer = s->proto->remote_ip;
uint len = a->u.ptr->length;
/* Forbid zero next hop */
if (ipa_zero(nh[0]) && ((len != 32) || ipa_zero(nh[1])))
WITHDRAW(BAD_NEXT_HOP);
/* Forbid next hop equal to neighbor IP */
if (ipa_equal(peer, nh[0]) || ((len == 32) && ipa_equal(peer, nh[1])))
WITHDRAW(BAD_NEXT_HOP);
/* Forbid next hop with non-matching AF */
if ((ipa_is_ip4(nh[0]) != bgp_channel_is_ipv4(s->channel)) &&
!s->channel->ext_next_hop)
WITHDRAW(BAD_NEXT_HOP);
/* Just check if MPLS stack */
if (s->mpls && !bgp_find_attr(*to, BA_MPLS_LABEL_STACK))
WITHDRAW(NO_LABEL_STACK);
}
static uint
bgp_encode_next_hop_ip(struct bgp_write_state *s, eattr *a, byte *buf, uint size UNUSED)
{
/* This function is used only for MP-BGP, see bgp_encode_next_hop() for IPv4 BGP */
ip_addr *nh = (void *) a->u.ptr->data;
uint len = a->u.ptr->length;
ASSERT((len == 16) || (len == 32));
/*
* Both IPv4 and IPv6 next hops can be used (with ext_next_hop enabled). This
* is specified in RFC 5549 for IPv4 and in RFC 4798 for IPv6. The difference
* is that IPv4 address is directly encoded with IPv4 NLRI, but as IPv4-mapped
* IPv6 address with IPv6 NLRI.
*/
if (bgp_channel_is_ipv4(s->channel) && ipa_is_ip4(nh[0]))
{
put_ip4(buf, ipa_to_ip4(nh[0]));
return 4;
}
put_ip6(buf, ipa_to_ip6(nh[0]));
if (len == 32)
put_ip6(buf+16, ipa_to_ip6(nh[1]));
return len;
}
static void
bgp_decode_next_hop_ip(struct bgp_parse_state *s, byte *data, uint len, rta *a)
{
struct bgp_channel *c = s->channel;
struct adata *ad = lp_alloc_adata(s->pool, 32);
ip_addr *nh = (void *) ad->data;
if (len == 4)
{
nh[0] = ipa_from_ip4(get_ip4(data));
nh[1] = IPA_NONE;
}
else if (len == 16)
{
nh[0] = ipa_from_ip6(get_ip6(data));
nh[1] = IPA_NONE;
if (ipa_is_link_local(nh[0]))
{ nh[1] = nh[0]; nh[0] = IPA_NONE; }
}
else if (len == 32)
{
nh[0] = ipa_from_ip6(get_ip6(data));
nh[1] = ipa_from_ip6(get_ip6(data+16));
if (ipa_is_link_local(nh[0]))
{ nh[1] = nh[0]; nh[0] = IPA_NONE; }
if (ipa_is_ip4(nh[0]) || !ipa_is_link_local(nh[1]))
nh[1] = IPA_NONE;
}
else
bgp_parse_error(s, 9);
if (ipa_zero(nh[1]))
ad->length = 16;
if ((bgp_channel_is_ipv4(c) != ipa_is_ip4(nh[0])) && !c->ext_next_hop)
WITHDRAW(BAD_NEXT_HOP);
// XXXX validate next hop
bgp_set_attr_ptr(&(a->eattrs), s->pool, BA_NEXT_HOP, 0, ad);
bgp_apply_next_hop(s, a, nh[0], nh[1]);
}
static uint
bgp_encode_next_hop_vpn(struct bgp_write_state *s, eattr *a, byte *buf, uint size UNUSED)
{
ip_addr *nh = (void *) a->u.ptr->data;
uint len = a->u.ptr->length;
ASSERT((len == 16) || (len == 32));
/*
* Both IPv4 and IPv6 next hops can be used (with ext_next_hop enabled). This
* is specified in RFC 5549 for VPNv4 and in RFC 4659 for VPNv6. The difference
* is that IPv4 address is directly encoded with VPNv4 NLRI, but as IPv4-mapped
* IPv6 address with VPNv6 NLRI.
*/
if (bgp_channel_is_ipv4(s->channel) && ipa_is_ip4(nh[0]))
{
put_u64(buf, 0); /* VPN RD is 0 */
put_ip4(buf+8, ipa_to_ip4(nh[0]));
return 12;
}
put_u64(buf, 0); /* VPN RD is 0 */
put_ip6(buf+8, ipa_to_ip6(nh[0]));
if (len == 16)
return 24;
put_u64(buf+24, 0); /* VPN RD is 0 */
put_ip6(buf+32, ipa_to_ip6(nh[1]));
return 48;
}
static void
bgp_decode_next_hop_vpn(struct bgp_parse_state *s, byte *data, uint len, rta *a)
{
struct bgp_channel *c = s->channel;
struct adata *ad = lp_alloc_adata(s->pool, 32);
ip_addr *nh = (void *) ad->data;
if (len == 12)
{
nh[0] = ipa_from_ip4(get_ip4(data+8));
nh[1] = IPA_NONE;
}
else if (len == 24)
{
nh[0] = ipa_from_ip6(get_ip6(data+8));
nh[1] = IPA_NONE;
if (ipa_is_link_local(nh[0]))
{ nh[1] = nh[0]; nh[0] = IPA_NONE; }
}
else if (len == 48)
{
nh[0] = ipa_from_ip6(get_ip6(data+8));
nh[1] = ipa_from_ip6(get_ip6(data+32));
if (ipa_is_ip4(nh[0]) || !ip6_is_link_local(nh[1]))
nh[1] = IPA_NONE;
}
else
bgp_parse_error(s, 9);
if (ipa_zero(nh[1]))
ad->length = 16;
/* XXXX which error */
if ((get_u64(data) != 0) || ((len == 48) && (get_u64(data+24) != 0)))
bgp_parse_error(s, 9);
if ((bgp_channel_is_ipv4(c) != ipa_is_ip4(nh[0])) && !c->ext_next_hop)
WITHDRAW(BAD_NEXT_HOP);
// XXXX validate next hop
bgp_set_attr_ptr(&(a->eattrs), s->pool, BA_NEXT_HOP, 0, ad);
bgp_apply_next_hop(s, a, nh[0], nh[1]);
}
static uint
bgp_encode_next_hop_none(struct bgp_write_state *s UNUSED, eattr *a UNUSED, byte *buf UNUSED, uint size UNUSED)
{
return 0;
}
static void
bgp_decode_next_hop_none(struct bgp_parse_state *s UNUSED, byte *data UNUSED, uint len UNUSED, rta *a UNUSED)
{
/*
* Although we expect no next hop and RFC 7606 7.11 states that attribute
* MP_REACH_NLRI with unexpected next hop length is considered malformed,
* FlowSpec RFC 5575 4 states that next hop shall be ignored on receipt.
*/
return;
}
static void
bgp_update_next_hop_none(struct bgp_export_state *s, eattr *a, ea_list **to)
{
/* NEXT_HOP shall not pass */
if (a)
bgp_unset_attr(to, s->pool, BA_NEXT_HOP);
}
/*
* UPDATE
*/
static void
bgp_rte_update(struct bgp_parse_state *s, net_addr *n, u32 path_id, rta *a0)
{
if (path_id != s->last_id)
{
s->last_src = rt_get_source(&s->proto->p, path_id);
s->last_id = path_id;
rta_free(s->cached_rta);
s->cached_rta = NULL;
}
if (!a0)
{
/* Route withdraw */
rte_update3(&s->channel->c, n, NULL, s->last_src);
return;
}
/* Prepare cached route attributes */
if (s->cached_rta == NULL)
{
a0->src = s->last_src;
/* Workaround for rta_lookup() breaking eattrs */
ea_list *ea = a0->eattrs;
s->cached_rta = rta_lookup(a0);
a0->eattrs = ea;
}
rta *a = rta_clone(s->cached_rta);
rte *e = rte_get_temp(a);
e->pflags = 0;
e->u.bgp.suppressed = 0;
e->u.bgp.stale = -1;
rte_update3(&s->channel->c, n, e, s->last_src);
}
static void
bgp_encode_mpls_labels(struct bgp_write_state *s UNUSED, const adata *mpls, byte **pos, uint *size, byte *pxlen)
{
const u32 dummy = 0;
const u32 *labels = mpls ? (const u32 *) mpls->data : &dummy;
uint lnum = mpls ? (mpls->length / 4) : 1;
for (uint i = 0; i < lnum; i++)
{
put_u24(*pos, labels[i] << 4);
ADVANCE(*pos, *size, 3);
}
/* Add bottom-of-stack flag */
(*pos)[-1] |= BGP_MPLS_BOS;
*pxlen += 24 * lnum;
}
static void
bgp_decode_mpls_labels(struct bgp_parse_state *s, byte **pos, uint *len, uint *pxlen, rta *a)
{
u32 labels[BGP_MPLS_MAX], label;
uint lnum = 0;
do {
if (*pxlen < 24)
bgp_parse_error(s, 1);
label = get_u24(*pos);
labels[lnum++] = label >> 4;
ADVANCE(*pos, *len, 3);
*pxlen -= 24;
/* RFC 8277 2.4 - withdraw does not have variable-size MPLS stack but
fixed-size 24-bit Compatibility field, which MUST be ignored */
if (!a && !s->err_withdraw)
return;
}
while (!(label & BGP_MPLS_BOS));
if (!a)
return;
/* Attach MPLS attribute unless we already have one */
if (!s->mpls_labels)
{
s->mpls_labels = lp_alloc_adata(s->pool, 4*BGP_MPLS_MAX);
bgp_set_attr_ptr(&(a->eattrs), s->pool, BA_MPLS_LABEL_STACK, 0, s->mpls_labels);
}
/* Overwrite data in the attribute */
s->mpls_labels->length = 4*lnum;
memcpy(s->mpls_labels->data, labels, 4*lnum);
/* Update next hop entry in rta */
bgp_apply_mpls_labels(s, a, labels, lnum);
/* Attributes were changed, invalidate cached entry */
rta_free(s->cached_rta);
s->cached_rta = NULL;
return;
}
static uint
bgp_encode_nlri_ip4(struct bgp_write_state *s, struct bgp_bucket *buck, byte *buf, uint size)
{
byte *pos = buf;
while (!EMPTY_LIST(buck->prefixes) && (size >= BGP_NLRI_MAX))
{
struct bgp_prefix *px = HEAD(buck->prefixes);
struct net_addr_ip4 *net = (void *) px->net;
/* Encode path ID */
if (s->add_path)
{
put_u32(pos, px->path_id);
ADVANCE(pos, size, 4);
}
/* Encode prefix length */
*pos = net->pxlen;
ADVANCE(pos, size, 1);
/* Encode MPLS labels */
if (s->mpls)
bgp_encode_mpls_labels(s, s->mpls_labels, &pos, &size, pos - 1);
/* Encode prefix body */
ip4_addr a = ip4_hton(net->prefix);
uint b = (net->pxlen + 7) / 8;
memcpy(pos, &a, b);
ADVANCE(pos, size, b);
bgp_free_prefix(s->channel, px);
}
return pos - buf;
}
static void
bgp_decode_nlri_ip4(struct bgp_parse_state *s, byte *pos, uint len, rta *a)
{
while (len)
{
net_addr_ip4 net;
u32 path_id = 0;
/* Decode path ID */
if (s->add_path)
{
if (len < 5)
bgp_parse_error(s, 1);
path_id = get_u32(pos);
ADVANCE(pos, len, 4);
}
/* Decode prefix length */
uint l = *pos;
ADVANCE(pos, len, 1);
if (len < ((l + 7) / 8))
bgp_parse_error(s, 1);
/* Decode MPLS labels */
if (s->mpls)
bgp_decode_mpls_labels(s, &pos, &len, &l, a);
if (l > IP4_MAX_PREFIX_LENGTH)
bgp_parse_error(s, 10);
/* Decode prefix body */
ip4_addr addr = IP4_NONE;
uint b = (l + 7) / 8;
memcpy(&addr, pos, b);
ADVANCE(pos, len, b);
net = NET_ADDR_IP4(ip4_ntoh(addr), l);
net_normalize_ip4(&net);
// XXXX validate prefix
bgp_rte_update(s, (net_addr *) &net, path_id, a);
}
}
static uint
bgp_encode_nlri_ip6(struct bgp_write_state *s, struct bgp_bucket *buck, byte *buf, uint size)
{
byte *pos = buf;
while (!EMPTY_LIST(buck->prefixes) && (size >= BGP_NLRI_MAX))
{
struct bgp_prefix *px = HEAD(buck->prefixes);
struct net_addr_ip6 *net = (void *) px->net;
/* Encode path ID */
if (s->add_path)
{
put_u32(pos, px->path_id);
ADVANCE(pos, size, 4);
}
/* Encode prefix length */
*pos = net->pxlen;
ADVANCE(pos, size, 1);
/* Encode MPLS labels */
if (s->mpls)
bgp_encode_mpls_labels(s, s->mpls_labels, &pos, &size, pos - 1);
/* Encode prefix body */
ip6_addr a = ip6_hton(net->prefix);
uint b = (net->pxlen + 7) / 8;
memcpy(pos, &a, b);
ADVANCE(pos, size, b);
bgp_free_prefix(s->channel, px);
}
return pos - buf;
}
static void
bgp_decode_nlri_ip6(struct bgp_parse_state *s, byte *pos, uint len, rta *a)
{
while (len)
{
net_addr_ip6 net;
u32 path_id = 0;
/* Decode path ID */
if (s->add_path)
{
if (len < 5)
bgp_parse_error(s, 1);
path_id = get_u32(pos);
ADVANCE(pos, len, 4);
}
/* Decode prefix length */
uint l = *pos;
ADVANCE(pos, len, 1);
if (len < ((l + 7) / 8))
bgp_parse_error(s, 1);
/* Decode MPLS labels */
if (s->mpls)
bgp_decode_mpls_labels(s, &pos, &len, &l, a);
if (l > IP6_MAX_PREFIX_LENGTH)
bgp_parse_error(s, 10);
/* Decode prefix body */
ip6_addr addr = IP6_NONE;
uint b = (l + 7) / 8;
memcpy(&addr, pos, b);
ADVANCE(pos, len, b);
net = NET_ADDR_IP6(ip6_ntoh(addr), l);
net_normalize_ip6(&net);
// XXXX validate prefix
bgp_rte_update(s, (net_addr *) &net, path_id, a);
}
}
static uint
bgp_encode_nlri_vpn4(struct bgp_write_state *s, struct bgp_bucket *buck, byte *buf, uint size)
{
byte *pos = buf;
while (!EMPTY_LIST(buck->prefixes) && (size >= BGP_NLRI_MAX))
{
struct bgp_prefix *px = HEAD(buck->prefixes);
struct net_addr_vpn4 *net = (void *) px->net;
/* Encode path ID */
if (s->add_path)
{
put_u32(pos, px->path_id);
ADVANCE(pos, size, 4);
}
/* Encode prefix length */
*pos = 64 + net->pxlen;
ADVANCE(pos, size, 1);
/* Encode MPLS labels */
if (s->mpls)
bgp_encode_mpls_labels(s, s->mpls_labels, &pos, &size, pos - 1);
/* Encode route distinguisher */
put_u64(pos, net->rd);
ADVANCE(pos, size, 8);
/* Encode prefix body */
ip4_addr a = ip4_hton(net->prefix);
uint b = (net->pxlen + 7) / 8;
memcpy(pos, &a, b);
ADVANCE(pos, size, b);
bgp_free_prefix(s->channel, px);
}
return pos - buf;
}
static void
bgp_decode_nlri_vpn4(struct bgp_parse_state *s, byte *pos, uint len, rta *a)
{
while (len)
{
net_addr_vpn4 net;
u32 path_id = 0;
/* Decode path ID */
if (s->add_path)
{
if (len < 5)
bgp_parse_error(s, 1);
path_id = get_u32(pos);
ADVANCE(pos, len, 4);
}
/* Decode prefix length */
uint l = *pos;
ADVANCE(pos, len, 1);
if (len < ((l + 7) / 8))
bgp_parse_error(s, 1);
/* Decode MPLS labels */
if (s->mpls)
bgp_decode_mpls_labels(s, &pos, &len, &l, a);
/* Decode route distinguisher */
if (l < 64)
bgp_parse_error(s, 1);
u64 rd = get_u64(pos);
ADVANCE(pos, len, 8);
l -= 64;
if (l > IP4_MAX_PREFIX_LENGTH)
bgp_parse_error(s, 10);
/* Decode prefix body */
ip4_addr addr = IP4_NONE;
uint b = (l + 7) / 8;
memcpy(&addr, pos, b);
ADVANCE(pos, len, b);
net = NET_ADDR_VPN4(ip4_ntoh(addr), l, rd);
net_normalize_vpn4(&net);
// XXXX validate prefix
bgp_rte_update(s, (net_addr *) &net, path_id, a);
}
}
static uint
bgp_encode_nlri_vpn6(struct bgp_write_state *s, struct bgp_bucket *buck, byte *buf, uint size)
{
byte *pos = buf;
while (!EMPTY_LIST(buck->prefixes) && (size >= BGP_NLRI_MAX))
{
struct bgp_prefix *px = HEAD(buck->prefixes);
struct net_addr_vpn6 *net = (void *) px->net;
/* Encode path ID */
if (s->add_path)
{
put_u32(pos, px->path_id);
ADVANCE(pos, size, 4);
}
/* Encode prefix length */
*pos = 64 + net->pxlen;
ADVANCE(pos, size, 1);
/* Encode MPLS labels */
if (s->mpls)
bgp_encode_mpls_labels(s, s->mpls_labels, &pos, &size, pos - 1);
/* Encode route distinguisher */
put_u64(pos, net->rd);
ADVANCE(pos, size, 8);
/* Encode prefix body */
ip6_addr a = ip6_hton(net->prefix);
uint b = (net->pxlen + 7) / 8;
memcpy(pos, &a, b);
ADVANCE(pos, size, b);
bgp_free_prefix(s->channel, px);
}
return pos - buf;
}
static void
bgp_decode_nlri_vpn6(struct bgp_parse_state *s, byte *pos, uint len, rta *a)
{
while (len)
{
net_addr_vpn6 net;
u32 path_id = 0;
/* Decode path ID */
if (s->add_path)
{
if (len < 5)
bgp_parse_error(s, 1);
path_id = get_u32(pos);
ADVANCE(pos, len, 4);
}
/* Decode prefix length */
uint l = *pos;
ADVANCE(pos, len, 1);
if (len < ((l + 7) / 8))
bgp_parse_error(s, 1);
/* Decode MPLS labels */
if (s->mpls)
bgp_decode_mpls_labels(s, &pos, &len, &l, a);
/* Decode route distinguisher */
if (l < 64)
bgp_parse_error(s, 1);
u64 rd = get_u64(pos);
ADVANCE(pos, len, 8);
l -= 64;
if (l > IP6_MAX_PREFIX_LENGTH)
bgp_parse_error(s, 10);
/* Decode prefix body */
ip6_addr addr = IP6_NONE;
uint b = (l + 7) / 8;
memcpy(&addr, pos, b);
ADVANCE(pos, len, b);
net = NET_ADDR_VPN6(ip6_ntoh(addr), l, rd);
net_normalize_vpn6(&net);
// XXXX validate prefix
bgp_rte_update(s, (net_addr *) &net, path_id, a);
}
}
static uint
bgp_encode_nlri_flow4(struct bgp_write_state *s, struct bgp_bucket *buck, byte *buf, uint size)
{
byte *pos = buf;
while (!EMPTY_LIST(buck->prefixes) && (size >= 4))
{
struct bgp_prefix *px = HEAD(buck->prefixes);
struct net_addr_flow4 *net = (void *) px->net;
uint flen = net->length - sizeof(net_addr_flow4);
/* Encode path ID */
if (s->add_path)
{
put_u32(pos, px->path_id);
ADVANCE(pos, size, 4);
}
if (flen > size)
break;
/* Copy whole flow data including length */
memcpy(pos, net->data, flen);
ADVANCE(pos, size, flen);
bgp_free_prefix(s->channel, px);
}
return pos - buf;
}
static void
bgp_decode_nlri_flow4(struct bgp_parse_state *s, byte *pos, uint len, rta *a)
{
while (len)
{
u32 path_id = 0;
/* Decode path ID */
if (s->add_path)
{
if (len < 4)
bgp_parse_error(s, 1);
path_id = get_u32(pos);
ADVANCE(pos, len, 4);
}
if (len < 2)
bgp_parse_error(s, 1);
/* Decode flow length */
uint hlen = flow_hdr_length(pos);
uint dlen = flow_read_length(pos);
uint flen = hlen + dlen;
byte *data = pos + hlen;
if (len < flen)
bgp_parse_error(s, 1);
/* Validate flow data */
enum flow_validated_state r = flow4_validate(data, dlen);
if (r != FLOW_ST_VALID)
{
log(L_REMOTE "%s: Invalid flow route: %s", s->proto->p.name, flow_validated_state_str(r));
bgp_parse_error(s, 1);
}
ip4_addr px = IP4_NONE;
uint pxlen = 0;
/* Decode dst prefix */
if (data[0] == FLOW_TYPE_DST_PREFIX)
{
px = flow_read_ip4_part(data);
pxlen = flow_read_pxlen(data);
}
/* Prepare the flow */
net_addr *n = alloca(sizeof(struct net_addr_flow4) + flen);
net_fill_flow4(n, px, pxlen, pos, flen);
ADVANCE(pos, len, flen);
bgp_rte_update(s, n, path_id, a);
}
}
static uint
bgp_encode_nlri_flow6(struct bgp_write_state *s, struct bgp_bucket *buck, byte *buf, uint size)
{
byte *pos = buf;
while (!EMPTY_LIST(buck->prefixes) && (size >= 4))
{
struct bgp_prefix *px = HEAD(buck->prefixes);
struct net_addr_flow6 *net = (void *) px->net;
uint flen = net->length - sizeof(net_addr_flow6);
/* Encode path ID */
if (s->add_path)
{
put_u32(pos, px->path_id);
ADVANCE(pos, size, 4);
}
if (flen > size)
break;
/* Copy whole flow data including length */
memcpy(pos, net->data, flen);
ADVANCE(pos, size, flen);
bgp_free_prefix(s->channel, px);
}
return pos - buf;
}
static void
bgp_decode_nlri_flow6(struct bgp_parse_state *s, byte *pos, uint len, rta *a)
{
while (len)
{
u32 path_id = 0;
/* Decode path ID */
if (s->add_path)
{
if (len < 4)
bgp_parse_error(s, 1);
path_id = get_u32(pos);
ADVANCE(pos, len, 4);
}
if (len < 2)
bgp_parse_error(s, 1);
/* Decode flow length */
uint hlen = flow_hdr_length(pos);
uint dlen = flow_read_length(pos);
uint flen = hlen + dlen;
byte *data = pos + hlen;
if (len < flen)
bgp_parse_error(s, 1);
/* Validate flow data */
enum flow_validated_state r = flow6_validate(data, dlen);
if (r != FLOW_ST_VALID)
{
log(L_REMOTE "%s: Invalid flow route: %s", s->proto->p.name, flow_validated_state_str(r));
bgp_parse_error(s, 1);
}
ip6_addr px = IP6_NONE;
uint pxlen = 0;
/* Decode dst prefix */
if (data[0] == FLOW_TYPE_DST_PREFIX)
{
px = flow_read_ip6_part(data);
pxlen = flow_read_pxlen(data);
}
/* Prepare the flow */
net_addr *n = alloca(sizeof(struct net_addr_flow6) + flen);
net_fill_flow6(n, px, pxlen, pos, flen);
ADVANCE(pos, len, flen);
bgp_rte_update(s, n, path_id, a);
}
}
static const struct bgp_af_desc bgp_af_table[] = {
{
.afi = BGP_AF_IPV4,
.net = NET_IP4,
.name = "ipv4",
.encode_nlri = bgp_encode_nlri_ip4,
.decode_nlri = bgp_decode_nlri_ip4,
.encode_next_hop = bgp_encode_next_hop_ip,
.decode_next_hop = bgp_decode_next_hop_ip,
.update_next_hop = bgp_update_next_hop_ip,
},
{
.afi = BGP_AF_IPV4_MC,
.net = NET_IP4,
.name = "ipv4-mc",
.encode_nlri = bgp_encode_nlri_ip4,
.decode_nlri = bgp_decode_nlri_ip4,
.encode_next_hop = bgp_encode_next_hop_ip,
.decode_next_hop = bgp_decode_next_hop_ip,
.update_next_hop = bgp_update_next_hop_ip,
},
{
.afi = BGP_AF_IPV4_MPLS,
.net = NET_IP4,
.mpls = 1,
.name = "ipv4-mpls",
.encode_nlri = bgp_encode_nlri_ip4,
.decode_nlri = bgp_decode_nlri_ip4,
.encode_next_hop = bgp_encode_next_hop_ip,
.decode_next_hop = bgp_decode_next_hop_ip,
.update_next_hop = bgp_update_next_hop_ip,
},
{
.afi = BGP_AF_IPV6,
.net = NET_IP6,
.name = "ipv6",
.encode_nlri = bgp_encode_nlri_ip6,
.decode_nlri = bgp_decode_nlri_ip6,
.encode_next_hop = bgp_encode_next_hop_ip,
.decode_next_hop = bgp_decode_next_hop_ip,
.update_next_hop = bgp_update_next_hop_ip,
},
{
.afi = BGP_AF_IPV6_MC,
.net = NET_IP6,
.name = "ipv6-mc",
.encode_nlri = bgp_encode_nlri_ip6,
.decode_nlri = bgp_decode_nlri_ip6,
.encode_next_hop = bgp_encode_next_hop_ip,
.decode_next_hop = bgp_decode_next_hop_ip,
.update_next_hop = bgp_update_next_hop_ip,
},
{
.afi = BGP_AF_IPV6_MPLS,
.net = NET_IP6,
.mpls = 1,
.name = "ipv6-mpls",
.encode_nlri = bgp_encode_nlri_ip6,
.decode_nlri = bgp_decode_nlri_ip6,
.encode_next_hop = bgp_encode_next_hop_ip,
.decode_next_hop = bgp_decode_next_hop_ip,
.update_next_hop = bgp_update_next_hop_ip,
},
{
.afi = BGP_AF_VPN4_MPLS,
.net = NET_VPN4,
.mpls = 1,
.name = "vpn4-mpls",
.encode_nlri = bgp_encode_nlri_vpn4,
.decode_nlri = bgp_decode_nlri_vpn4,
.encode_next_hop = bgp_encode_next_hop_vpn,
.decode_next_hop = bgp_decode_next_hop_vpn,
.update_next_hop = bgp_update_next_hop_ip,
},
{
.afi = BGP_AF_VPN6_MPLS,
.net = NET_VPN6,
.mpls = 1,
.name = "vpn6-mpls",
.encode_nlri = bgp_encode_nlri_vpn6,
.decode_nlri = bgp_decode_nlri_vpn6,
.encode_next_hop = bgp_encode_next_hop_vpn,
.decode_next_hop = bgp_decode_next_hop_vpn,
.update_next_hop = bgp_update_next_hop_ip,
},
{
.afi = BGP_AF_VPN4_MC,
.net = NET_VPN4,
.name = "vpn4-mc",
.encode_nlri = bgp_encode_nlri_vpn4,
.decode_nlri = bgp_decode_nlri_vpn4,
.encode_next_hop = bgp_encode_next_hop_vpn,
.decode_next_hop = bgp_decode_next_hop_vpn,
.update_next_hop = bgp_update_next_hop_ip,
},
{
.afi = BGP_AF_VPN6_MC,
.net = NET_VPN6,
.name = "vpn6-mc",
.encode_nlri = bgp_encode_nlri_vpn6,
.decode_nlri = bgp_decode_nlri_vpn6,
.encode_next_hop = bgp_encode_next_hop_vpn,
.decode_next_hop = bgp_decode_next_hop_vpn,
.update_next_hop = bgp_update_next_hop_ip,
},
{
.afi = BGP_AF_FLOW4,
.net = NET_FLOW4,
.no_igp = 1,
.name = "flow4",
.encode_nlri = bgp_encode_nlri_flow4,
.decode_nlri = bgp_decode_nlri_flow4,
.encode_next_hop = bgp_encode_next_hop_none,
.decode_next_hop = bgp_decode_next_hop_none,
.update_next_hop = bgp_update_next_hop_none,
},
{
.afi = BGP_AF_FLOW6,
.net = NET_FLOW6,
.no_igp = 1,
.name = "flow6",
.encode_nlri = bgp_encode_nlri_flow6,
.decode_nlri = bgp_decode_nlri_flow6,
.encode_next_hop = bgp_encode_next_hop_none,
.decode_next_hop = bgp_decode_next_hop_none,
.update_next_hop = bgp_update_next_hop_none,
},
};
const struct bgp_af_desc *
bgp_get_af_desc(u32 afi)
{
uint i;
for (i = 0; i < ARRAY_SIZE(bgp_af_table); i++)
if (bgp_af_table[i].afi == afi)
return &bgp_af_table[i];
return NULL;
}
static inline uint
bgp_encode_nlri(struct bgp_write_state *s, struct bgp_bucket *buck, byte *buf, byte *end)
{
return s->channel->desc->encode_nlri(s, buck, buf, end - buf);
}
static inline uint
bgp_encode_next_hop(struct bgp_write_state *s, eattr *nh, byte *buf)
{
return s->channel->desc->encode_next_hop(s, nh, buf, 255);
}
void
bgp_update_next_hop(struct bgp_export_state *s, eattr *a, ea_list **to)
{
s->channel->desc->update_next_hop(s, a, to);
}
#define MAX_ATTRS_LENGTH (end-buf+BGP_HEADER_LENGTH - 1024)
static byte *
bgp_create_ip_reach(struct bgp_write_state *s, struct bgp_bucket *buck, byte *buf, byte *end)
{
/*
* 2 B Withdrawn Routes Length (zero)
* --- IPv4 Withdrawn Routes NLRI (unused)
* 2 B Total Path Attribute Length
* var Path Attributes
* var IPv4 Network Layer Reachability Information
*/
int lr, la;
la = bgp_encode_attrs(s, buck->eattrs, buf+4, buf + MAX_ATTRS_LENGTH);
if (la < 0)
{
/* Attribute list too long */
bgp_withdraw_bucket(s->channel, buck);
return NULL;
}
put_u16(buf+0, 0);
put_u16(buf+2, la);
lr = bgp_encode_nlri(s, buck, buf+4+la, end);
return buf+4+la+lr;
}
static byte *
bgp_create_mp_reach(struct bgp_write_state *s, struct bgp_bucket *buck, byte *buf, byte *end)
{
/*
* 2 B IPv4 Withdrawn Routes Length (zero)
* --- IPv4 Withdrawn Routes NLRI (unused)
* 2 B Total Path Attribute Length
* 1 B MP_REACH_NLRI hdr - Attribute Flags
* 1 B MP_REACH_NLRI hdr - Attribute Type Code
* 2 B MP_REACH_NLRI hdr - Length of Attribute Data
* 2 B MP_REACH_NLRI data - Address Family Identifier
* 1 B MP_REACH_NLRI data - Subsequent Address Family Identifier
* 1 B MP_REACH_NLRI data - Length of Next Hop Network Address
* var MP_REACH_NLRI data - Network Address of Next Hop
* 1 B MP_REACH_NLRI data - Reserved (zero)
* var MP_REACH_NLRI data - Network Layer Reachability Information
* var Rest of Path Attributes
* --- IPv4 Network Layer Reachability Information (unused)
*/
int lh, lr, la; /* Lengths of next hop, NLRI and attributes */
/* Begin of MP_REACH_NLRI atribute */
buf[4] = BAF_OPTIONAL | BAF_EXT_LEN;
buf[5] = BA_MP_REACH_NLRI;
put_u16(buf+6, 0); /* Will be fixed later */
put_af3(buf+8, s->channel->afi);
byte *pos = buf+11;
/* Encode attributes to temporary buffer */
byte *abuf = alloca(MAX_ATTRS_LENGTH);
la = bgp_encode_attrs(s, buck->eattrs, abuf, abuf + MAX_ATTRS_LENGTH);
if (la < 0)
{
/* Attribute list too long */
bgp_withdraw_bucket(s->channel, buck);
return NULL;
}
/* Encode the next hop */
lh = bgp_encode_next_hop(s, s->mp_next_hop, pos+1);
*pos = lh;
pos += 1+lh;
/* Reserved field */
*pos++ = 0;
/* Encode the NLRI */
lr = bgp_encode_nlri(s, buck, pos, end - la);
pos += lr;
/* End of MP_REACH_NLRI atribute, update data length */
put_u16(buf+6, pos-buf-8);
/* Copy remaining attributes */
memcpy(pos, abuf, la);
pos += la;
/* Initial UPDATE fields */
put_u16(buf+0, 0);
put_u16(buf+2, pos-buf-4);
return pos;
}
#undef MAX_ATTRS_LENGTH
static byte *
bgp_create_ip_unreach(struct bgp_write_state *s, struct bgp_bucket *buck, byte *buf, byte *end)
{
/*
* 2 B Withdrawn Routes Length
* var IPv4 Withdrawn Routes NLRI
* 2 B Total Path Attribute Length (zero)
* --- Path Attributes (unused)
* --- IPv4 Network Layer Reachability Information (unused)
*/
uint len = bgp_encode_nlri(s, buck, buf+2, end);
put_u16(buf+0, len);
put_u16(buf+2+len, 0);
return buf+4+len;
}
static byte *
bgp_create_mp_unreach(struct bgp_write_state *s, struct bgp_bucket *buck, byte *buf, byte *end)
{
/*
* 2 B Withdrawn Routes Length (zero)
* --- IPv4 Withdrawn Routes NLRI (unused)
* 2 B Total Path Attribute Length
* 1 B MP_UNREACH_NLRI hdr - Attribute Flags
* 1 B MP_UNREACH_NLRI hdr - Attribute Type Code
* 2 B MP_UNREACH_NLRI hdr - Length of Attribute Data
* 2 B MP_UNREACH_NLRI data - Address Family Identifier
* 1 B MP_UNREACH_NLRI data - Subsequent Address Family Identifier
* var MP_UNREACH_NLRI data - Network Layer Reachability Information
* --- IPv4 Network Layer Reachability Information (unused)
*/
uint len = bgp_encode_nlri(s, buck, buf+11, end);
put_u16(buf+0, 0);
put_u16(buf+2, 7+len);
/* Begin of MP_UNREACH_NLRI atribute */
buf[4] = BAF_OPTIONAL | BAF_EXT_LEN;
buf[5] = BA_MP_UNREACH_NLRI;
put_u16(buf+6, 3+len);
put_af3(buf+8, s->channel->afi);
return buf+11+len;
}
static byte *
bgp_create_update(struct bgp_channel *c, byte *buf)
{
struct bgp_proto *p = (void *) c->c.proto;
struct bgp_bucket *buck;
byte *end = buf + (bgp_max_packet_length(p->conn) - BGP_HEADER_LENGTH);
byte *res = NULL;
again: ;
/* Initialize write state */
struct bgp_write_state s = {
.proto = p,
.channel = c,
.pool = bgp_linpool,
.mp_reach = (c->afi != BGP_AF_IPV4) || c->ext_next_hop,
.as4_session = p->as4_session,
.add_path = c->add_path_tx,
.mpls = c->desc->mpls,
};
/* Try unreachable bucket */
if ((buck = c->withdraw_bucket) && !EMPTY_LIST(buck->prefixes))
{
res = (c->afi == BGP_AF_IPV4) && !c->ext_next_hop ?
bgp_create_ip_unreach(&s, buck, buf, end):
bgp_create_mp_unreach(&s, buck, buf, end);
goto done;
}
/* Try reachable buckets */
if (!EMPTY_LIST(c->bucket_queue))
{
buck = HEAD(c->bucket_queue);
/* Cleanup empty buckets */
if (EMPTY_LIST(buck->prefixes))
{
bgp_free_bucket(c, buck);
goto again;
}
res = !s.mp_reach ?
bgp_create_ip_reach(&s, buck, buf, end):
bgp_create_mp_reach(&s, buck, buf, end);
if (EMPTY_LIST(buck->prefixes))
bgp_free_bucket(c, buck);
else
bgp_defer_bucket(c, buck);
if (!res)
goto again;
goto done;
}
/* No more prefixes to send */
return NULL;
done:
BGP_TRACE_RL(&rl_snd_update, D_PACKETS, "Sending UPDATE");
p->stats.tx_updates++;
lp_flush(s.pool);
return res;
}
static byte *
bgp_create_ip_end_mark(struct bgp_channel *c UNUSED, byte *buf)
{
/* Empty update packet */
put_u32(buf, 0);
return buf+4;
}
static byte *
bgp_create_mp_end_mark(struct bgp_channel *c, byte *buf)
{
put_u16(buf+0, 0);
put_u16(buf+2, 6); /* length 4--9 */
/* Empty MP_UNREACH_NLRI atribute */
buf[4] = BAF_OPTIONAL;
buf[5] = BA_MP_UNREACH_NLRI;
buf[6] = 3; /* Length 7--9 */
put_af3(buf+7, c->afi);
return buf+10;
}
static byte *
bgp_create_end_mark(struct bgp_channel *c, byte *buf)
{
struct bgp_proto *p = (void *) c->c.proto;
BGP_TRACE(D_PACKETS, "Sending END-OF-RIB");
p->stats.tx_updates++;
return (c->afi == BGP_AF_IPV4) ?
bgp_create_ip_end_mark(c, buf):
bgp_create_mp_end_mark(c, buf);
}
static inline void
bgp_rx_end_mark(struct bgp_parse_state *s, u32 afi)
{
struct bgp_proto *p = s->proto;
struct bgp_channel *c = bgp_get_channel(p, afi);
BGP_TRACE(D_PACKETS, "Got END-OF-RIB");
if (!c)
DISCARD(BAD_AFI, BGP_AFI(afi), BGP_SAFI(afi));
if (c->load_state == BFS_LOADING)
c->load_state = BFS_NONE;
if (p->p.gr_recovery)
channel_graceful_restart_unlock(&c->c);
if (c->gr_active)
bgp_graceful_restart_done(c);
}
static inline void
bgp_decode_nlri(struct bgp_parse_state *s, u32 afi, byte *nlri, uint len, ea_list *ea, byte *nh, uint nh_len)
{
struct bgp_channel *c = bgp_get_channel(s->proto, afi);
rta *a = NULL;
if (!c)
DISCARD(BAD_AFI, BGP_AFI(afi), BGP_SAFI(afi));
s->channel = c;
s->add_path = c->add_path_rx;
s->mpls = c->desc->mpls;
s->last_id = 0;
s->last_src = s->proto->p.main_source;
/*
* IPv4 BGP and MP-BGP may be used together in one update, therefore we do not
* add BA_NEXT_HOP in bgp_decode_attrs(), but we add it here independently for
* IPv4 BGP and MP-BGP. We undo the attribute (and possibly others attached by
* decode_next_hop hooks) by restoring a->eattrs afterwards.
*/
if (ea)
{
a = allocz(RTA_MAX_SIZE);
a->source = RTS_BGP;
a->scope = SCOPE_UNIVERSE;
a->from = s->proto->remote_ip;
a->eattrs = ea;
c->desc->decode_next_hop(s, nh, nh_len, a);
bgp_finish_attrs(s, a);
/* Handle withdraw during next hop decoding */
if (s->err_withdraw)
a = NULL;
}
c->desc->decode_nlri(s, nlri, len, a);
rta_free(s->cached_rta);
s->cached_rta = NULL;
}
static void
bgp_rx_update(struct bgp_conn *conn, byte *pkt, uint len)
{
struct bgp_proto *p = conn->bgp;
ea_list *ea = NULL;
BGP_TRACE_RL(&rl_rcv_update, D_PACKETS, "Got UPDATE");
p->last_rx_update = current_time();
p->stats.rx_updates++;
/* 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);
/* Initialize parse state */
struct bgp_parse_state s = {
.proto = p,
.pool = bgp_linpool,
.as4_session = p->as4_session,
};
/* Parse error handler */
if (setjmp(s.err_jmpbuf))
{
bgp_error(conn, 3, s.err_subcode, NULL, 0);
goto done;
}
/* Check minimal length */
if (len < 23)
{ bgp_error(conn, 1, 2, pkt+16, 2); return; }
/* Skip fixed header */
uint pos = 19;
/*
* UPDATE message format
*
* 2 B IPv4 Withdrawn Routes Length
* var IPv4 Withdrawn Routes NLRI
* 2 B Total Path Attribute Length
* var Path Attributes
* var IPv4 Reachable Routes NLRI
*/
s.ip_unreach_len = get_u16(pkt + pos);
s.ip_unreach_nlri = pkt + pos + 2;
pos += 2 + s.ip_unreach_len;
if (pos + 2 > len)
bgp_parse_error(&s, 1);
s.attr_len = get_u16(pkt + pos);
s.attrs = pkt + pos + 2;
pos += 2 + s.attr_len;
if (pos > len)
bgp_parse_error(&s, 1);
s.ip_reach_len = len - pos;
s.ip_reach_nlri = pkt + pos;
if (s.attr_len)
ea = bgp_decode_attrs(&s, s.attrs, s.attr_len);
else
ea = NULL;
/* Check for End-of-RIB marker */
if (!s.attr_len && !s.ip_unreach_len && !s.ip_reach_len)
{ bgp_rx_end_mark(&s, BGP_AF_IPV4); goto done; }
/* Check for MP End-of-RIB marker */
if ((s.attr_len < 8) && !s.ip_unreach_len && !s.ip_reach_len &&
!s.mp_reach_len && !s.mp_unreach_len && s.mp_unreach_af)
{ bgp_rx_end_mark(&s, s.mp_unreach_af); goto done; }
if (s.ip_unreach_len)
bgp_decode_nlri(&s, BGP_AF_IPV4, s.ip_unreach_nlri, s.ip_unreach_len, NULL, NULL, 0);
if (s.mp_unreach_len)
bgp_decode_nlri(&s, s.mp_unreach_af, s.mp_unreach_nlri, s.mp_unreach_len, NULL, NULL, 0);
if (s.ip_reach_len)
bgp_decode_nlri(&s, BGP_AF_IPV4, s.ip_reach_nlri, s.ip_reach_len,
ea, s.ip_next_hop_data, s.ip_next_hop_len);
if (s.mp_reach_len)
bgp_decode_nlri(&s, s.mp_reach_af, s.mp_reach_nlri, s.mp_reach_len,
ea, s.mp_next_hop_data, s.mp_next_hop_len);
done:
rta_free(s.cached_rta);
lp_flush(s.pool);
return;
}
static uint
bgp_find_update_afi(byte *pos, uint len)
{
/*
* This is stripped-down version of bgp_rx_update(), bgp_decode_attrs() and
* bgp_decode_mp_[un]reach_nlri() used by MRT code in order to find out which
* AFI/SAFI is associated with incoming UPDATE. Returns 0 for framing errors.
*/
if (len < 23)
return 0;
/* Assume there is no withrawn NLRI, read lengths and move to attribute list */
uint wlen = get_u16(pos + 19);
uint alen = get_u16(pos + 21);
ADVANCE(pos, len, 23);
/* Either non-zero withdrawn NLRI, non-zero reachable NLRI, or IPv4 End-of-RIB */
if ((wlen != 0) || (alen < len) || !alen)
return BGP_AF_IPV4;
if (alen > len)
return 0;
/* Process attribute list (alen == len) */
while (len)
{
if (len < 2)
return 0;
uint flags = pos[0];
uint code = pos[1];
ADVANCE(pos, len, 2);
uint ll = !(flags & BAF_EXT_LEN) ? 1 : 2;
if (len < ll)
return 0;
/* Read attribute length and move to attribute body */
alen = (ll == 1) ? get_u8(pos) : get_u16(pos);
ADVANCE(pos, len, ll);
if (len < alen)
return 0;
/* Found MP NLRI */
if ((code == BA_MP_REACH_NLRI) || (code == BA_MP_UNREACH_NLRI))
{
if (alen < 3)
return 0;
return BGP_AF(get_u16(pos), pos[2]);
}
/* Move to the next attribute */
ADVANCE(pos, len, alen);
}
/* No basic or MP NLRI, but there are some attributes -> error */
return 0;
}
/*
* ROUTE-REFRESH
*/
static inline byte *
bgp_create_route_refresh(struct bgp_channel *c, byte *buf)
{
struct bgp_proto *p = (void *) c->c.proto;
BGP_TRACE(D_PACKETS, "Sending ROUTE-REFRESH");
/* Original route refresh request, RFC 2918 */
put_af4(buf, c->afi);
buf[2] = BGP_RR_REQUEST;
return buf+4;
}
static inline byte *
bgp_create_begin_refresh(struct bgp_channel *c, byte *buf)
{
struct bgp_proto *p = (void *) c->c.proto;
BGP_TRACE(D_PACKETS, "Sending BEGIN-OF-RR");
/* Demarcation of beginning of route refresh (BoRR), RFC 7313 */
put_af4(buf, c->afi);
buf[2] = BGP_RR_BEGIN;
return buf+4;
}
static inline byte *
bgp_create_end_refresh(struct bgp_channel *c, byte *buf)
{
struct bgp_proto *p = (void *) c->c.proto;
BGP_TRACE(D_PACKETS, "Sending END-OF-RR");
/* Demarcation of ending of route refresh (EoRR), RFC 7313 */
put_af4(buf, c->afi);
buf[2] = BGP_RR_END;
return buf+4;
}
static void
bgp_rx_route_refresh(struct bgp_conn *conn, byte *pkt, uint len)
{
struct bgp_proto *p = conn->bgp;
if (conn->state != BS_ESTABLISHED)
{ bgp_error(conn, 5, fsm_err_subcode[conn->state], NULL, 0); return; }
if (!conn->local_caps->route_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; }
if (len > (BGP_HEADER_LENGTH + 4))
{ bgp_error(conn, 7, 1, pkt, MIN(len, 2048)); return; }
struct bgp_channel *c = bgp_get_channel(p, get_af4(pkt+19));
if (!c)
{
log(L_WARN "%s: Got ROUTE-REFRESH subtype %u for AF %u.%u, ignoring",
p->p.name, pkt[21], get_u16(pkt+19), pkt[22]);
return;
}
/* RFC 7313 redefined reserved field as RR message subtype */
uint subtype = p->enhanced_refresh ? pkt[21] : BGP_RR_REQUEST;
switch (subtype)
{
case BGP_RR_REQUEST:
BGP_TRACE(D_PACKETS, "Got ROUTE-REFRESH");
channel_request_feeding(&c->c);
break;
case BGP_RR_BEGIN:
BGP_TRACE(D_PACKETS, "Got BEGIN-OF-RR");
bgp_refresh_begin(c);
break;
case BGP_RR_END:
BGP_TRACE(D_PACKETS, "Got END-OF-RR");
bgp_refresh_end(c);
break;
default:
log(L_WARN "%s: Got ROUTE-REFRESH message with unknown subtype %u, ignoring",
p->p.name, subtype);
break;
}
}
static inline struct bgp_channel *
bgp_get_channel_to_send(struct bgp_proto *p, struct bgp_conn *conn)
{
uint i = conn->last_channel;
/* Try the last channel, but at most several times */
if ((conn->channels_to_send & (1 << i)) &&
(conn->last_channel_count < 16))
goto found;
/* Find channel with non-zero channels_to_send */
do
{
i++;
if (i >= p->channel_count)
i = 0;
}
while (! (conn->channels_to_send & (1 << i)));
/* Use that channel */
conn->last_channel = i;
conn->last_channel_count = 0;
found:
conn->last_channel_count++;
return p->channel_map[i];
}
static inline int
bgp_send(struct bgp_conn *conn, uint type, uint len)
{
sock *sk = conn->sk;
byte *buf = sk->tbuf;
conn->bgp->stats.tx_messages++;
conn->bgp->stats.tx_bytes += len;
memset(buf, 0xff, 16); /* Marker */
put_u16(buf+16, len);
buf[18] = type;
return sk_send(sk, len);
}
/**
* 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;
struct bgp_channel *c;
byte *buf, *pkt, *end;
uint s;
if (!conn->sk)
return 0;
buf = conn->sk->tbuf;
pkt = buf + BGP_HEADER_LENGTH;
s = conn->packets_to_send;
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))
{
conn->packets_to_send = 1 << PKT_SCHEDULE_CLOSE;
end = bgp_create_notification(conn, pkt);
return bgp_send(conn, PKT_NOTIFICATION, end - buf);
}
else if (s & (1 << PKT_OPEN))
{
conn->packets_to_send &= ~(1 << PKT_OPEN);
end = bgp_create_open(conn, pkt);
return bgp_send(conn, PKT_OPEN, end - buf);
}
else if (s & (1 << PKT_KEEPALIVE))
{
conn->packets_to_send &= ~(1 << PKT_KEEPALIVE);
BGP_TRACE(D_PACKETS, "Sending KEEPALIVE");
bgp_start_timer(conn->keepalive_timer, conn->keepalive_time);
return bgp_send(conn, PKT_KEEPALIVE, BGP_HEADER_LENGTH);
}
else while (conn->channels_to_send)
{
c = bgp_get_channel_to_send(p, conn);
s = c->packets_to_send;
if (s & (1 << PKT_ROUTE_REFRESH))
{
c->packets_to_send &= ~(1 << PKT_ROUTE_REFRESH);
end = bgp_create_route_refresh(c, pkt);
return bgp_send(conn, PKT_ROUTE_REFRESH, end - buf);
}
else if (s & (1 << PKT_BEGIN_REFRESH))
{
/* BoRR is a subtype of RR, but uses separate bit in packets_to_send */
c->packets_to_send &= ~(1 << PKT_BEGIN_REFRESH);
end = bgp_create_begin_refresh(c, pkt);
return bgp_send(conn, PKT_ROUTE_REFRESH, end - buf);
}
else if (s & (1 << PKT_UPDATE))
{
end = bgp_create_update(c, pkt);
if (end)
return bgp_send(conn, PKT_UPDATE, end - buf);
/* No update to send, perhaps we need to send End-of-RIB or EoRR */
c->packets_to_send = 0;
conn->channels_to_send &= ~(1 << c->index);
if (c->feed_state == BFS_LOADED)
{
c->feed_state = BFS_NONE;
end = bgp_create_end_mark(c, pkt);
return bgp_send(conn, PKT_UPDATE, end - buf);
}
else if (c->feed_state == BFS_REFRESHED)
{
c->feed_state = BFS_NONE;
end = bgp_create_end_refresh(c, pkt);
return bgp_send(conn, PKT_ROUTE_REFRESH, end - buf);
}
}
else if (s)
bug("Channel packets_to_send: %x", s);
c->packets_to_send = 0;
conn->channels_to_send &= ~(1 << c->index);
}
return 0;
}
/**
* bgp_schedule_packet - schedule a packet for transmission
* @conn: connection
* @c: channel
* @type: packet type
*
* Schedule a packet of type @type to be sent as soon as possible.
*/
void
bgp_schedule_packet(struct bgp_conn *conn, struct bgp_channel *c, int type)
{
ASSERT(conn->sk);
DBG("BGP: Scheduling packet type %d\n", type);
if (c)
{
if (! conn->channels_to_send)
{
conn->last_channel = c->index;
conn->last_channel_count = 0;
}
c->packets_to_send |= 1 << type;
conn->channels_to_send |= 1 << c->index;
}
else
conn->packets_to_send |= 1 << type;
if ((conn->sk->tpos == conn->sk->tbuf) && !ev_active(conn->tx_ev))
ev_schedule(conn->tx_ev);
}
void
bgp_kick_tx(void *vconn)
{
struct bgp_conn *conn = vconn;
DBG("BGP: kicking TX\n");
uint max = 1024;
while (--max && (bgp_fire_tx(conn) > 0))
;
if (!max && !ev_active(conn->tx_ev))
ev_schedule(conn->tx_ev);
}
void
bgp_tx(sock *sk)
{
struct bgp_conn *conn = sk->data;
DBG("BGP: TX hook\n");
uint max = 1024;
while (--max && (bgp_fire_tx(conn) > 0))
;
if (!max && !ev_active(conn->tx_ev))
ev_schedule(conn->tx_ev);
}
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" }, /* [RFC5492] */
{ 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" },
{ 7, 0, "Invalid ROUTE-REFRESH message" }, /* [RFC7313] */
{ 7, 1, "Invalid ROUTE-REFRESH message length" } /* [RFC7313] */
};
/**
* 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(uint code, uint subcode)
{
static char buff[32];
uint 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 %u.%u", code, subcode);
return buff;
}
/* RFC 8203 - shutdown communication message */
static int
bgp_handle_message(struct bgp_proto *p, byte *data, uint len, byte **bp)
{
byte *msg = data + 1;
uint msg_len = data[0];
uint i;
/* Handle zero length message */
if (msg_len == 0)
return 1;
/* Handle proper message */
if (msg_len + 1 > len)
return 0;
/* Some elementary cleanup */
for (i = 0; i < msg_len; i++)
if (msg[i] < ' ')
msg[i] = ' ';
proto_set_message(&p->p, msg, msg_len);
*bp += bsprintf(*bp, ": \"%s\"", p->p.message);
return 1;
}
void
bgp_log_error(struct bgp_proto *p, u8 class, char *msg, uint code, uint subcode, byte *data, uint len)
{
byte argbuf[256+16], *t = argbuf;
uint i;
/* Don't report Cease messages generated by myself */
if (code == 6 && class == BE_BGP_TX)
return;
/* Reset shutdown message */
if ((code == 6) && ((subcode == 2) || (subcode == 4)))
proto_set_message(&p->p, NULL, 0);
if (len)
{
/* Bad peer AS - we would like to print the AS */
if ((code == 2) && (subcode == 2) && ((len == 2) || (len == 4)))
{
t += bsprintf(t, ": %u", (len == 2) ? get_u16(data) : get_u32(data));
goto done;
}
/* RFC 8203 - shutdown communication */
if (((code == 6) && ((subcode == 2) || (subcode == 4))))
if (bgp_handle_message(p, data, len, &t))
goto done;
*t++ = ':';
*t++ = ' ';
if (len > 16)
len = 16;
for (i=0; i<len; i++)
t += bsprintf(t, "%02x", data[i]);
}
done:
*t = 0;
const byte *dsc = bgp_error_dsc(code, subcode);
log(L_REMOTE "%s: %s: %s%s", p->p.name, msg, dsc, argbuf);
}
static void
bgp_rx_notification(struct bgp_conn *conn, byte *pkt, uint len)
{
struct bgp_proto *p = conn->bgp;
if (len < 21)
{ bgp_error(conn, 1, 2, pkt+16, 2); return; }
uint code = pkt[19];
uint 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);
bgp_conn_enter_close_state(conn);
bgp_schedule_packet(conn, NULL, PKT_SCHEDULE_CLOSE);
if (err)
{
bgp_update_startup_delay(p);
bgp_stop(p, 0, NULL, 0);
}
else
{
uint subcode_bit = 1 << ((subcode <= 8) ? subcode : 0);
if (p->cf->disable_after_cease & subcode_bit)
{
log(L_INFO "%s: Disabled after Cease notification", p->p.name);
p->startup_delay = 0;
p->p.disabled = 1;
}
}
}
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);
if (conn->state == BS_OPENCONFIRM)
{ bgp_conn_enter_established_state(conn); return; }
if (conn->state != BS_ESTABLISHED)
bgp_error(conn, 5, fsm_err_subcode[conn->state], 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, uint len)
{
byte type = pkt[18];
DBG("BGP: Got packet %02x (%d bytes)\n", type, len);
conn->bgp->stats.rx_messages++;
conn->bgp->stats.rx_bytes += len;
if (conn->bgp->p.mrtdump & MD_MESSAGES)
bgp_dump_message(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, uint size)
{
struct bgp_conn *conn = sk->data;
byte *pkt_start = sk->rbuf;
byte *end = pkt_start + size;
uint 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(conn)))
{
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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