/* BGP carrying label information
* Copyright (C) 2013 Cumulus Networks, Inc.
*
* This file is part of GNU Zebra.
*
* GNU Zebra is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2, or (at your option) any
* later version.
*
* GNU Zebra is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; see the file COPYING; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <zebra.h>
#include "command.h"
#include "thread.h"
#include "prefix.h"
#include "zclient.h"
#include "stream.h"
#include "network.h"
#include "log.h"
#include "memory.h"
#include "nexthop.h"
#include "mpls.h"
#include "bgpd/bgpd.h"
#include "bgpd/bgp_table.h"
#include "bgpd/bgp_route.h"
#include "bgpd/bgp_attr.h"
#include "bgpd/bgp_label.h"
#include "bgpd/bgp_packet.h"
#include "bgpd/bgp_debug.h"
#include "bgpd/bgp_errors.h"
extern struct zclient *zclient;
int bgp_parse_fec_update(void)
{
struct stream *s;
struct bgp_dest *dest;
struct bgp *bgp;
struct bgp_table *table;
struct prefix p;
uint32_t label;
afi_t afi;
safi_t safi;
s = zclient->ibuf;
memset(&p, 0, sizeof(struct prefix));
p.family = stream_getw(s);
p.prefixlen = stream_getc(s);
stream_get(p.u.val, s, PSIZE(p.prefixlen));
label = stream_getl(s);
/* hack for the bgp instance & SAFI = have to send/receive it */
afi = family2afi(p.family);
safi = SAFI_UNICAST;
bgp = bgp_get_default();
if (!bgp) {
zlog_debug("no default bgp instance");
return -1;
}
table = bgp->rib[afi][safi];
if (!table) {
zlog_debug("no %u unicast table", p.family);
return -1;
}
dest = bgp_node_lookup(table, &p);
if (!dest) {
zlog_debug("no node for the prefix");
return -1;
}
/* treat it as implicit withdraw - the label is invalid */
if (label == MPLS_INVALID_LABEL)
bgp_unset_valid_label(&dest->local_label);
else {
label_ntop(label, 1, &dest->local_label);
bgp_set_valid_label(&dest->local_label);
}
SET_FLAG(dest->flags, BGP_NODE_LABEL_CHANGED);
bgp_dest_unlock_node(dest);
bgp_process(bgp, dest, afi, safi);
return 1;
}
mpls_label_t bgp_adv_label(struct bgp_dest *dest, struct bgp_path_info *pi,
struct peer *to, afi_t afi, safi_t safi)
{
struct peer *from;
mpls_label_t remote_label;
int reflect;
if (!dest || !pi || !to)
return MPLS_INVALID_LABEL;
remote_label = pi->extra ? pi->extra->label[0] : MPLS_INVALID_LABEL;
from = pi->peer;
reflect =
((from->sort == BGP_PEER_IBGP) && (to->sort == BGP_PEER_IBGP));
if (reflect
&& !CHECK_FLAG(to->af_flags[afi][safi],
PEER_FLAG_FORCE_NEXTHOP_SELF))
return remote_label;
if (CHECK_FLAG(to->af_flags[afi][safi], PEER_FLAG_NEXTHOP_UNCHANGED))
return remote_label;
return dest->local_label;
}
/**
* This is passed as the callback function to bgp_labelpool.c:bgp_lp_get()
* by bgp_reg_dereg_for_label() when a label needs to be obtained from
* label pool.
* Note that it will reject the allocated label if a label index is found,
* because the label index supposes predictable labels
*/
int bgp_reg_for_label_callback(mpls_label_t new_label, void *labelid,
bool allocated)
{
struct bgp_path_info *pi;
struct bgp_dest *dest;
pi = labelid;
/* Is this path still valid? */
if (!bgp_path_info_unlock(pi)) {
if (BGP_DEBUG(labelpool, LABELPOOL))
zlog_debug(
"%s: bgp_path_info is no longer valid, ignoring",
__func__);
return -1;
}
dest = pi->net;
if (BGP_DEBUG(labelpool, LABELPOOL))
zlog_debug("%s: FEC %pRN label=%u, allocated=%d", __func__,
bgp_dest_to_rnode(dest), new_label, allocated);
if (!allocated) {
/*
* previously-allocated label is now invalid
*/
if (pi->attr->label_index == MPLS_INVALID_LABEL_INDEX
&& pi->attr->label != MPLS_LABEL_NONE
&& CHECK_FLAG(dest->flags, BGP_NODE_REGISTERED_FOR_LABEL)) {
bgp_unregister_for_label(dest);
label_ntop(MPLS_LABEL_IMPLICIT_NULL, 1,
&dest->local_label);
bgp_set_valid_label(&dest->local_label);
}
return 0;
}
/*
* label index is assigned, this should be handled by SR-related code,
* so retry FEC registration and then reject label allocation for
* it to be released to label pool
*/
if (pi->attr->label_index != MPLS_INVALID_LABEL_INDEX) {
flog_err(
EC_BGP_LABEL,
"%s: FEC %pRN Rejecting allocated label %u as Label Index is %u",
__func__, bgp_dest_to_rnode(dest), new_label,
pi->attr->label_index);
bgp_register_for_label(pi->net, pi);
return -1;
}
if (pi->attr->label != MPLS_INVALID_LABEL) {
if (new_label == pi->attr->label) {
/* already have same label, accept but do nothing */
return 0;
}
/* Shouldn't happen: different label allocation */
flog_err(EC_BGP_LABEL,
"%s: %pRN had label %u but got new assignment %u",
__func__, bgp_dest_to_rnode(dest), pi->attr->label,
new_label);
/* continue means use new one */
}
label_ntop(new_label, 1, &dest->local_label);
bgp_set_valid_label(&dest->local_label);
/*
* Get back to registering the FEC
*/
bgp_register_for_label(pi->net, pi);
return 0;
}
void bgp_reg_dereg_for_label(struct bgp_dest *dest, struct bgp_path_info *pi,
bool reg)
{
bool with_label_index = false;
struct stream *s;
const struct prefix *p;
mpls_label_t *local_label;
int command;
uint16_t flags = 0;
size_t flags_pos = 0;
char addr[PREFIX_STRLEN];
p = bgp_dest_get_prefix(dest);
local_label = &(dest->local_label);
/* this prevents the loop when we're called by
* bgp_reg_for_label_callback()
*/
bool have_label_to_reg = bgp_is_valid_label(local_label)
&& label_pton(local_label) != MPLS_LABEL_IMPLICIT_NULL;
if (reg) {
assert(pi);
/*
* Determine if we will let zebra should derive label from
* label index instead of bgpd requesting from label pool
*/
if (CHECK_FLAG(pi->attr->flag,
ATTR_FLAG_BIT(BGP_ATTR_PREFIX_SID))
&& pi->attr->label_index != BGP_INVALID_LABEL_INDEX) {
with_label_index = true;
} else {
/*
* If no label index was provided -- assume any label
* from label pool will do. This means that label index
* always takes precedence over auto-assigned labels.
*/
if (!have_label_to_reg) {
if (BGP_DEBUG(labelpool, LABELPOOL)) {
prefix2str(p, addr, PREFIX_STRLEN);
zlog_debug("%s: Requesting label from LP for %s",
__func__, addr);
}
/* bgp_reg_for_label_callback() will call back
* __func__ when it gets a label from the pool.
* This means we'll never register FECs without
* valid labels.
*/
bgp_lp_get(LP_TYPE_BGP_LU, pi,
bgp_reg_for_label_callback);
return;
}
}
}
/* Check socket. */
if (!zclient || zclient->sock < 0)
return;
/* If the route node has a local_label assigned or the
* path node has an MPLS SR label index allowing zebra to
* derive the label, proceed with registration. */
s = zclient->obuf;
stream_reset(s);
command = (reg) ? ZEBRA_FEC_REGISTER : ZEBRA_FEC_UNREGISTER;
zclient_create_header(s, command, VRF_DEFAULT);
flags_pos = stream_get_endp(s); /* save position of 'flags' */
stream_putw(s, flags); /* initial flags */
stream_putw(s, PREFIX_FAMILY(p));
stream_put_prefix(s, p);
if (reg) {
if (have_label_to_reg) {
flags |= ZEBRA_FEC_REGISTER_LABEL;
stream_putl(s, label_pton(local_label));
} else if (with_label_index) {
flags |= ZEBRA_FEC_REGISTER_LABEL_INDEX;
stream_putl(s, pi->attr->label_index);
}
SET_FLAG(dest->flags, BGP_NODE_REGISTERED_FOR_LABEL);
} else
UNSET_FLAG(dest->flags, BGP_NODE_REGISTERED_FOR_LABEL);
/* Set length and flags */
stream_putw_at(s, 0, stream_get_endp(s));
/*
* We only need to write new flags if this is a register
*/
if (reg)
stream_putw_at(s, flags_pos, flags);
zclient_send_message(zclient);
}
static int bgp_nlri_get_labels(struct peer *peer, uint8_t *pnt, uint8_t plen,
mpls_label_t *label)
{
uint8_t *data = pnt;
uint8_t *lim = pnt + plen;
uint8_t llen = 0;
uint8_t label_depth = 0;
for (; data < lim; data += BGP_LABEL_BYTES) {
memcpy(label, data, BGP_LABEL_BYTES);
llen += BGP_LABEL_BYTES;
bgp_set_valid_label(label);
label_depth += 1;
if (bgp_is_withdraw_label(label) || label_bos(label))
break;
}
/* If we RX multiple labels we will end up keeping only the last
* one. We do not yet support a label stack greater than 1. */
if (label_depth > 1)
zlog_info("%s rcvd UPDATE with label stack %d deep", peer->host,
label_depth);
if (!(bgp_is_withdraw_label(label) || label_bos(label)))
flog_warn(
EC_BGP_INVALID_LABEL_STACK,
"%s rcvd UPDATE with invalid label stack - no bottom of stack",
peer->host);
return llen;
}
int bgp_nlri_parse_label(struct peer *peer, struct attr *attr,
struct bgp_nlri *packet)
{
uint8_t *pnt;
uint8_t *lim;
struct prefix p;
int psize = 0;
int prefixlen;
afi_t afi;
safi_t safi;
int addpath_encoded;
uint32_t addpath_id;
mpls_label_t label = MPLS_INVALID_LABEL;
uint8_t llen;
pnt = packet->nlri;
lim = pnt + packet->length;
afi = packet->afi;
safi = packet->safi;
addpath_id = 0;
addpath_encoded =
(CHECK_FLAG(peer->af_cap[afi][safi], PEER_CAP_ADDPATH_AF_RX_ADV)
&& CHECK_FLAG(peer->af_cap[afi][safi],
PEER_CAP_ADDPATH_AF_TX_RCV));
for (; pnt < lim; pnt += psize) {
/* Clear prefix structure. */
memset(&p, 0, sizeof(struct prefix));
if (addpath_encoded) {
/* When packet overflow occurs return immediately. */
if (pnt + BGP_ADDPATH_ID_LEN > lim)
return BGP_NLRI_PARSE_ERROR_PACKET_OVERFLOW;
memcpy(&addpath_id, pnt, BGP_ADDPATH_ID_LEN);
addpath_id = ntohl(addpath_id);
pnt += BGP_ADDPATH_ID_LEN;
}
/* Fetch prefix length. */
prefixlen = *pnt++;
p.family = afi2family(packet->afi);
psize = PSIZE(prefixlen);
/* sanity check against packet data */
if ((pnt + psize) > lim) {
flog_err(
EC_BGP_UPDATE_RCV,
"%s [Error] Update packet error / L-U (prefix length %d exceeds packet size %u)",
peer->host, prefixlen, (uint)(lim - pnt));
return BGP_NLRI_PARSE_ERROR_PACKET_OVERFLOW;
}
/* Fill in the labels */
llen = bgp_nlri_get_labels(peer, pnt, psize, &label);
p.prefixlen = prefixlen - BSIZE(llen);
/* There needs to be at least one label */
if (prefixlen < 24) {
flog_err(EC_BGP_UPDATE_RCV,
"%s [Error] Update packet error (wrong label length %d)",
peer->host, prefixlen);
bgp_notify_send(peer, BGP_NOTIFY_UPDATE_ERR,
BGP_NOTIFY_UPDATE_INVAL_NETWORK);
return BGP_NLRI_PARSE_ERROR_LABEL_LENGTH;
}
if ((afi == AFI_IP && p.prefixlen > 32)
|| (afi == AFI_IP6 && p.prefixlen > 128))
return BGP_NLRI_PARSE_ERROR_PREFIX_LENGTH;
/* Fetch prefix from NLRI packet */
memcpy(&p.u.prefix, pnt + llen, psize - llen);
/* Check address. */
if (afi == AFI_IP && safi == SAFI_LABELED_UNICAST) {
if (IN_CLASSD(ntohl(p.u.prefix4.s_addr))) {
/* From RFC4271 Section 6.3:
*
* If a prefix in the NLRI field is semantically
* incorrect
* (e.g., an unexpected multicast IP address),
* an error SHOULD
* be logged locally, and the prefix SHOULD be
* ignored.
*/
flog_err(
EC_BGP_UPDATE_RCV,
"%s: IPv4 labeled-unicast NLRI is multicast address %s, ignoring",
peer->host, inet_ntoa(p.u.prefix4));
continue;
}
}
/* Check address. */
if (afi == AFI_IP6 && safi == SAFI_LABELED_UNICAST) {
if (IN6_IS_ADDR_LINKLOCAL(&p.u.prefix6)) {
char buf[BUFSIZ];
flog_err(
EC_BGP_UPDATE_RCV,
"%s: IPv6 labeled-unicast NLRI is link-local address %s, ignoring",
peer->host,
inet_ntop(AF_INET6, &p.u.prefix6, buf,
BUFSIZ));
continue;
}
if (IN6_IS_ADDR_MULTICAST(&p.u.prefix6)) {
char buf[BUFSIZ];
flog_err(
EC_BGP_UPDATE_RCV,
"%s: IPv6 unicast NLRI is multicast address %s, ignoring",
peer->host,
inet_ntop(AF_INET6, &p.u.prefix6, buf,
BUFSIZ));
continue;
}
}
if (attr) {
bgp_update(peer, &p, addpath_id, attr, packet->afi,
SAFI_UNICAST, ZEBRA_ROUTE_BGP,
BGP_ROUTE_NORMAL, NULL, &label, 1, 0, NULL);
} else {
bgp_withdraw(peer, &p, addpath_id, attr, packet->afi,
SAFI_UNICAST, ZEBRA_ROUTE_BGP,
BGP_ROUTE_NORMAL, NULL, &label, 1, NULL);
}
}
/* Packet length consistency check. */
if (pnt != lim) {
flog_err(
EC_BGP_UPDATE_RCV,
"%s [Error] Update packet error / L-U (%td data remaining after parsing)",
peer->host, lim - pnt);
return BGP_NLRI_PARSE_ERROR_PACKET_LENGTH;
}
return BGP_NLRI_PARSE_OK;
}