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bird/proto/bgp/bgp.h
Ondrej Zajicek (work) 1950a479c0 BGP: Allow exchanging LOCAL_PREF with eBGP peers 
Adds option 'allow bgp_local_pref' to override the usual restriction of
LOCAL_PREF on eBGP sessions.

Thanks to Lennert Buytenhek for the patch.
2017-02-23 16:32:07 +01:00

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/*
* BIRD -- The Border Gateway Protocol
*
* (c) 2000 Martin Mares <mj@ucw.cz>
*
* Can be freely distributed and used under the terms of the GNU GPL.
*/
#ifndef _BIRD_BGP_H_
#define _BIRD_BGP_H_
#include <stdint.h>
#include "nest/route.h"
#include "nest/bfd.h"
#include "lib/hash.h"
struct linpool;
struct eattr;
struct bgp_config {
struct proto_config c;
u32 local_as, remote_as;
ip_addr remote_ip;
ip_addr source_addr; /* Source address to use */
struct iface *iface; /* Interface for link-local addresses */
u16 remote_port; /* Neighbor destination port */
int multihop; /* Number of hops if multihop */
int ttl_security; /* Enable TTL security [RFC5082] */
int next_hop_self; /* Always set next hop to local IP address */
int next_hop_keep; /* Do not touch next hop attribute */
int missing_lladdr; /* What we will do when we don' know link-local addr, see MLL_* */
int gw_mode; /* How we compute route gateway from next_hop attr, see GW_* */
int compare_path_lengths; /* Use path lengths when selecting best route */
int med_metric; /* Compare MULTI_EXIT_DISC even between routes from differen ASes */
int igp_metric; /* Use IGP metrics when selecting best route */
int prefer_older; /* Prefer older routes according to RFC 5004 */
int deterministic_med; /* Use more complicated algo to have strict RFC 4271 MED comparison */
u32 default_local_pref; /* Default value for LOCAL_PREF attribute */
u32 default_med; /* Default value for MULTI_EXIT_DISC attribute */
int capabilities; /* Enable capability handshake [RFC3392] */
int enable_refresh; /* Enable local support for route refresh [RFC2918] */
int enable_as4; /* Enable local support for 4B AS numbers [RFC4893] */
int enable_extended_messages; /* Enable local support for extended messages [draft] */
u32 rr_cluster_id; /* Route reflector cluster ID, if different from local ID */
int rr_client; /* Whether neighbor is RR client of me */
int rs_client; /* Whether neighbor is RS client of me */
int advertise_ipv4; /* Whether we should add IPv4 capability advertisement to OPEN message */
int passive; /* Do not initiate outgoing connection */
int interpret_communities; /* Hardwired handling of well-known communities */
int secondary; /* Accept also non-best routes (i.e. RA_ACCEPTED) */
int add_path; /* Use ADD-PATH extension [RFC7911] */
int allow_local_as; /* Allow that number of local ASNs in incoming AS_PATHs */
int allow_local_pref; /* Allow LOCAL_PREF in EBGP sessions */
int gr_mode; /* Graceful restart mode (BGP_GR_*) */
int setkey; /* Set MD5 password to system SA/SP database */
unsigned gr_time; /* Graceful restart timeout */
unsigned connect_delay_time; /* Minimum delay between connect attempts */
unsigned connect_retry_time; /* Timeout for connect attempts */
unsigned hold_time, initial_hold_time;
unsigned keepalive_time;
unsigned error_amnesia_time; /* Errors are forgotten after */
unsigned error_delay_time_min; /* Time to wait after an error is detected */
unsigned error_delay_time_max;
unsigned disable_after_error; /* Disable the protocol when error is detected */
char *password; /* Password used for MD5 authentication */
struct rtable_config *igp_table; /* Table used for recursive next hop lookups */
int check_link; /* Use iface link state for liveness detection */
int bfd; /* Use BFD for liveness detection */
};
#define MLL_SELF 1
#define MLL_DROP 2
#define MLL_IGNORE 3
#define GW_DIRECT 1
#define GW_RECURSIVE 2
#define ADD_PATH_RX 1
#define ADD_PATH_TX 2
#define ADD_PATH_FULL 3
#define BGP_GR_ABLE 1
#define BGP_GR_AWARE 2
/* For peer_gr_flags */
#define BGP_GRF_RESTART 0x80
/* For peer_gr_aflags */
#define BGP_GRF_FORWARDING 0x80
struct bgp_conn {
struct bgp_proto *bgp;
struct birdsock *sk;
uint state; /* State of connection state machine */
struct timer *connect_retry_timer;
struct timer *hold_timer;
struct timer *keepalive_timer;
struct event *tx_ev;
int packets_to_send; /* Bitmap of packet types to be sent */
int notify_code, notify_subcode, notify_size;
byte *notify_data;
u32 advertised_as; /* Temporary value for AS number received */
int start_state; /* protocol start_state snapshot when connection established */
u8 peer_refresh_support; /* Peer supports route refresh [RFC2918] */
u8 peer_as4_support; /* Peer supports 4B AS numbers [RFC4893] */
u8 peer_add_path; /* Peer supports ADD-PATH [RFC7911] */
u8 peer_enhanced_refresh_support; /* Peer supports enhanced refresh [RFC7313] */
u8 peer_gr_aware;
u8 peer_gr_able;
u16 peer_gr_time;
u8 peer_gr_flags;
u8 peer_gr_aflags;
u8 peer_ext_messages_support; /* Peer supports extended message length [draft] */
unsigned hold_time, keepalive_time; /* Times calculated from my and neighbor's requirements */
};
struct bgp_proto {
struct proto p;
struct bgp_config *cf; /* Shortcut to BGP configuration */
u32 local_as, remote_as;
int start_state; /* Substates that partitions BS_START */
u8 is_internal; /* Internal BGP connection (local_as == remote_as) */
u8 as4_session; /* Session uses 4B AS numbers in AS_PATH (both sides support it) */
u8 add_path_rx; /* Session expects receive of ADD-PATH extended NLRI */
u8 add_path_tx; /* Session expects transmit of ADD-PATH extended NLRI */
u8 ext_messages; /* Session allows to use extended messages (both sides support it) */
u32 local_id; /* BGP identifier of this router */
u32 remote_id; /* BGP identifier of the neighbor */
u32 rr_cluster_id; /* Route reflector cluster ID */
int rr_client; /* Whether neighbor is RR client of me */
int rs_client; /* Whether neighbor is RS client of me */
u8 gr_ready; /* Neighbor could do graceful restart */
u8 gr_active; /* Neighbor is doing graceful restart */
u8 feed_state; /* Feed state (TX) for EoR, RR packets, see BFS_* */
u8 load_state; /* Load state (RX) for EoR, RR packets, see BFS_* */
struct bgp_conn *conn; /* Connection we have established */
struct bgp_conn outgoing_conn; /* Outgoing connection we're working with */
struct bgp_conn incoming_conn; /* Incoming connection we have neither accepted nor rejected yet */
struct object_lock *lock; /* Lock for neighbor connection */
struct neighbor *neigh; /* Neighbor entry corresponding to remote ip, NULL if multihop */
struct bfd_request *bfd_req; /* BFD request, if BFD is used */
ip_addr source_addr; /* Local address used as an advertised next hop */
rtable *igp_table; /* Table used for recursive next hop lookups */
struct event *event; /* Event for respawning and shutting process */
struct timer *startup_timer; /* Timer used to delay protocol startup due to previous errors (startup_delay) */
struct timer *gr_timer; /* Timer waiting for reestablishment after graceful restart */
struct bgp_bucket **bucket_hash; /* Hash table of attribute buckets */
uint hash_size, hash_count, hash_limit;
HASH(struct bgp_prefix) prefix_hash; /* Prefixes to be sent */
slab *prefix_slab; /* Slab holding prefix nodes */
list bucket_queue; /* Queue of buckets to send */
struct bgp_bucket *withdraw_bucket; /* Withdrawn routes */
unsigned startup_delay; /* Time to delay protocol startup by due to errors */
bird_clock_t last_proto_error; /* Time of last error that leads to protocol stop */
u8 last_error_class; /* Error class of last error */
u32 last_error_code; /* Error code of last error. BGP protocol errors
are encoded as (bgp_err_code << 16 | bgp_err_subcode) */
#ifdef IPV6
byte *mp_reach_start, *mp_unreach_start; /* Multiprotocol BGP attribute notes */
unsigned mp_reach_len, mp_unreach_len;
ip_addr local_link; /* Link-level version of source_addr */
#endif
};
struct bgp_prefix {
struct {
ip_addr prefix;
int pxlen;
} n;
u32 path_id;
struct bgp_prefix *next;
node bucket_node; /* Node in per-bucket list */
};
struct bgp_bucket {
node send_node; /* Node in send queue */
struct bgp_bucket *hash_next, *hash_prev; /* Node in bucket hash table */
unsigned hash; /* Hash over extended attributes */
list prefixes; /* Prefixes in this buckets */
ea_list eattrs[0]; /* Per-bucket extended attributes */
};
#define BGP_PORT 179
#define BGP_VERSION 4
#define BGP_HEADER_LENGTH 19
#define BGP_MAX_MESSAGE_LENGTH 4096
#define BGP_MAX_EXT_MSG_LENGTH 65535
#define BGP_RX_BUFFER_SIZE 4096
#define BGP_TX_BUFFER_SIZE 4096
#define BGP_RX_BUFFER_EXT_SIZE 65535
#define BGP_TX_BUFFER_EXT_SIZE 65535
static inline uint bgp_max_packet_length(struct bgp_proto *p)
{ return p->ext_messages ? BGP_MAX_EXT_MSG_LENGTH : BGP_MAX_MESSAGE_LENGTH; }
extern struct linpool *bgp_linpool;
void bgp_start_timer(struct timer *t, int value);
void bgp_check_config(struct bgp_config *c);
void bgp_error(struct bgp_conn *c, unsigned code, unsigned subcode, byte *data, int len);
void bgp_close_conn(struct bgp_conn *c);
void bgp_update_startup_delay(struct bgp_proto *p);
void bgp_conn_enter_openconfirm_state(struct bgp_conn *conn);
void bgp_conn_enter_established_state(struct bgp_conn *conn);
void bgp_conn_enter_close_state(struct bgp_conn *conn);
void bgp_conn_enter_idle_state(struct bgp_conn *conn);
void bgp_handle_graceful_restart(struct bgp_proto *p);
void bgp_graceful_restart_done(struct bgp_proto *p);
void bgp_refresh_begin(struct bgp_proto *p);
void bgp_refresh_end(struct bgp_proto *p);
void bgp_store_error(struct bgp_proto *p, struct bgp_conn *c, u8 class, u32 code);
void bgp_stop(struct bgp_proto *p, unsigned subcode);
struct rte_source *bgp_find_source(struct bgp_proto *p, u32 path_id);
struct rte_source *bgp_get_source(struct bgp_proto *p, u32 path_id);
#ifdef LOCAL_DEBUG
#define BGP_FORCE_DEBUG 1
#else
#define BGP_FORCE_DEBUG 0
#endif
#define BGP_TRACE(flags, msg, args...) do { if ((p->p.debug & flags) || BGP_FORCE_DEBUG) \
log(L_TRACE "%s: " msg, p->p.name , ## args ); } while(0)
#define BGP_TRACE_RL(rl, flags, msg, args...) do { if ((p->p.debug & flags) || BGP_FORCE_DEBUG) \
log_rl(rl, L_TRACE "%s: " msg, p->p.name , ## args ); } while(0)
/* attrs.c */
/* Hack: although BA_NEXT_HOP attribute has type EAF_TYPE_IP_ADDRESS, in IPv6
* we store two addesses in it - a global address and a link local address.
*/
#ifdef IPV6
#define NEXT_HOP_LENGTH (2*sizeof(ip_addr))
static inline void set_next_hop(byte *b, ip_addr addr) { ((ip_addr *) b)[0] = addr; ((ip_addr *) b)[1] = IPA_NONE; }
#else
#define NEXT_HOP_LENGTH sizeof(ip_addr)
static inline void set_next_hop(byte *b, ip_addr addr) { ((ip_addr *) b)[0] = addr; }
#endif
void bgp_attach_attr(struct ea_list **to, struct linpool *pool, unsigned attr, uintptr_t val);
byte *bgp_attach_attr_wa(struct ea_list **to, struct linpool *pool, unsigned attr, unsigned len);
struct rta *bgp_decode_attrs(struct bgp_conn *conn, byte *a, uint len, struct linpool *pool, int mandatory);
int bgp_get_attr(struct eattr *e, byte *buf, int buflen);
int bgp_rte_better(struct rte *, struct rte *);
int bgp_rte_mergable(rte *pri, rte *sec);
int bgp_rte_recalculate(rtable *table, net *net, rte *new, rte *old, rte *old_best);
void bgp_rt_notify(struct proto *P, rtable *tbl UNUSED, net *n, rte *new, rte *old UNUSED, ea_list *attrs);
int bgp_import_control(struct proto *, struct rte **, struct ea_list **, struct linpool *);
void bgp_init_bucket_table(struct bgp_proto *);
void bgp_free_bucket_table(struct bgp_proto *p);
void bgp_free_bucket(struct bgp_proto *p, struct bgp_bucket *buck);
void bgp_init_prefix_table(struct bgp_proto *p, u32 order);
void bgp_free_prefix_table(struct bgp_proto *p);
void bgp_free_prefix(struct bgp_proto *p, struct bgp_prefix *bp);
uint bgp_encode_attrs(struct bgp_proto *p, byte *w, ea_list *attrs, int remains);
void bgp_get_route_info(struct rte *, byte *buf, struct ea_list *attrs);
inline static void bgp_attach_attr_ip(struct ea_list **to, struct linpool *pool, unsigned attr, ip_addr a)
{ *(ip_addr *) bgp_attach_attr_wa(to, pool, attr, sizeof(ip_addr)) = a; }
/* packets.c */
void mrt_dump_bgp_state_change(struct bgp_conn *conn, unsigned old, unsigned new);
void bgp_schedule_packet(struct bgp_conn *conn, int type);
void bgp_kick_tx(void *vconn);
void bgp_tx(struct birdsock *sk);
int bgp_rx(struct birdsock *sk, uint size);
const char * bgp_error_dsc(unsigned code, unsigned subcode);
void bgp_log_error(struct bgp_proto *p, u8 class, char *msg, unsigned code, unsigned subcode, byte *data, unsigned len);
/* Packet types */
#define PKT_OPEN 0x01
#define PKT_UPDATE 0x02
#define PKT_NOTIFICATION 0x03
#define PKT_KEEPALIVE 0x04
#define PKT_ROUTE_REFRESH 0x05 /* [RFC2918] */
#define PKT_BEGIN_REFRESH 0x1e /* Dummy type for BoRR packet [RFC7313] */
#define PKT_SCHEDULE_CLOSE 0x1f /* Used internally to schedule socket close */
/* Attributes */
#define BAF_OPTIONAL 0x80
#define BAF_TRANSITIVE 0x40
#define BAF_PARTIAL 0x20
#define BAF_EXT_LEN 0x10
#define BA_ORIGIN 0x01 /* [RFC1771] */ /* WM */
#define BA_AS_PATH 0x02 /* WM */
#define BA_NEXT_HOP 0x03 /* WM */
#define BA_MULTI_EXIT_DISC 0x04 /* ON */
#define BA_LOCAL_PREF 0x05 /* WD */
#define BA_ATOMIC_AGGR 0x06 /* WD */
#define BA_AGGREGATOR 0x07 /* OT */
#define BA_COMMUNITY 0x08 /* [RFC1997] */ /* OT */
#define BA_ORIGINATOR_ID 0x09 /* [RFC1966] */ /* ON */
#define BA_CLUSTER_LIST 0x0a /* ON */
/* We don't support these: */
#define BA_DPA 0x0b /* ??? */
#define BA_ADVERTISER 0x0c /* [RFC1863] */
#define BA_RCID_PATH 0x0d
#define BA_MP_REACH_NLRI 0x0e /* [RFC2283] */
#define BA_MP_UNREACH_NLRI 0x0f
#define BA_EXT_COMMUNITY 0x10 /* [RFC4360] */
#define BA_AS4_PATH 0x11 /* [RFC4893] */
#define BA_AS4_AGGREGATOR 0x12
#define BA_LARGE_COMMUNITY 0x20 /* [RFC8092] */
/* BGP connection states */
#define BS_IDLE 0
#define BS_CONNECT 1 /* Attempting to connect */
#define BS_ACTIVE 2 /* Waiting for connection retry & listening */
#define BS_OPENSENT 3
#define BS_OPENCONFIRM 4
#define BS_ESTABLISHED 5
#define BS_CLOSE 6 /* Used during transition to BS_IDLE */
#define BS_MAX 7
/* BGP start states
*
* Used in PS_START for fine-grained specification of starting state.
*
* When BGP protocol is started by core, it goes to BSS_PREPARE. When BGP
* protocol done what is neccessary to start itself (like acquiring the lock),
* it goes to BSS_CONNECT. When some connection attempt failed because of
* option or capability error, it goes to BSS_CONNECT_NOCAP.
*/
#define BSS_PREPARE 0 /* Used before ordinary BGP started, i. e. waiting for lock */
#define BSS_DELAY 1 /* Startup delay due to previous errors */
#define BSS_CONNECT 2 /* Ordinary BGP connecting */
#define BSS_CONNECT_NOCAP 3 /* Legacy BGP connecting (without capabilities) */
/* BGP feed states (TX)
*
* RFC 4724 specifies that an initial feed should end with End-of-RIB mark.
*
* RFC 7313 specifies that a route refresh should be demarcated by BoRR and EoRR packets.
*
* These states (stored in p->feed_state) are used to keep track of these
* requirements. When such feed is started, BFS_LOADING / BFS_REFRESHING is
* set. When it ended, BFS_LOADED / BFS_REFRESHED is set to schedule End-of-RIB
* or EoRR packet. When the packet is sent, the state returned to BFS_NONE.
*
* Note that when a non-demarcated feed (e.g. plain RFC 4271 initial load
* without End-of-RIB or plain RFC 2918 route refresh without BoRR/EoRR
* demarcation) is active, BFS_NONE is set.
*
* BFS_NONE, BFS_LOADING and BFS_REFRESHING are also used as load states (RX)
* with correspondent semantics (-, expecting End-of-RIB, expecting EoRR).
*/
#define BFS_NONE 0 /* No feed or original non-demarcated feed */
#define BFS_LOADING 1 /* Initial feed active, End-of-RIB planned */
#define BFS_LOADED 2 /* Loading done, End-of-RIB marker scheduled */
#define BFS_REFRESHING 3 /* Route refresh (introduced by BoRR) active */
#define BFS_REFRESHED 4 /* Refresh done, EoRR packet scheduled */
/* Error classes */
#define BE_NONE 0
#define BE_MISC 1 /* Miscellaneous error */
#define BE_SOCKET 2 /* Socket error */
#define BE_BGP_RX 3 /* BGP protocol error notification received */
#define BE_BGP_TX 4 /* BGP protocol error notification sent */
#define BE_AUTO_DOWN 5 /* Automatic shutdown */
#define BE_MAN_DOWN 6 /* Manual shutdown */
/* Misc error codes */
#define BEM_NEIGHBOR_LOST 1
#define BEM_INVALID_NEXT_HOP 2
#define BEM_INVALID_MD5 3 /* MD5 authentication kernel request failed (possibly not supported) */
#define BEM_NO_SOCKET 4
#define BEM_LINK_DOWN 5
#define BEM_BFD_DOWN 6
#define BEM_GRACEFUL_RESTART 7
/* Automatic shutdown error codes */
#define BEA_ROUTE_LIMIT_EXCEEDED 1
/* Well-known communities */
#define BGP_COMM_NO_EXPORT 0xffffff01 /* Don't export outside local AS / confed. */
#define BGP_COMM_NO_ADVERTISE 0xffffff02 /* Don't export at all */
#define BGP_COMM_NO_EXPORT_SUBCONFED 0xffffff03 /* NO_EXPORT even in local confederation */
/* Origins */
#define ORIGIN_IGP 0
#define ORIGIN_EGP 1
#define ORIGIN_INCOMPLETE 2
/* Address families */
#define BGP_AF_IPV4 1
#define BGP_AF_IPV6 2
#ifdef IPV6
#define BGP_AF BGP_AF_IPV6
#else
#define BGP_AF BGP_AF_IPV4
#endif
#endif
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