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BGP: Add option 'free bind'

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The BGP 'free bind' option applies the IP_FREEBIND/IPV6_FREEBIND
socket option for the BGP listening socket.

Thanks to Alexander Zubkov for the idea.
This commit is contained in:
Ondrej Zajicek (work) 2022-01-09 02:40:58 +01:00
parent 87a02489f3
commit 60e9def9ef
4 changed files with 17 additions and 4 deletions
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6
doc/bird.sgml
View file

@ -2412,6 +2412,12 @@ using the following configuration parameters:
same address family and using the same local port) should have set
<cf/strict bind/, or none of them. Default: disabled.
<tag><label id="bgp-free-bind">free bind <m/switch/</tag>
Use IP_FREEBIND socket option for the listening socket, which allows
binding to an IP address not (yet) assigned to an interface. Note that
all BGP instances that share a listening socket should have the same
value of the <cf/freebind/ option. Default: disabled.
<tag><label id="bgp-check-link">check link <M>switch</M></tag>
BGP could use hardware link state into consideration. If enabled,
BIRD tracks the link state of the associated interface and when link

11
proto/bgp/bgp.c
View file

@ -157,6 +157,8 @@ bgp_open(struct bgp_proto *p)
ip_addr addr = p->cf->strict_bind ? p->cf->local_ip :
(p->ipv4 ? IPA_NONE4 : IPA_NONE6);
uint port = p->cf->local_port;
uint flags = p->cf->free_bind ? SKF_FREEBIND : 0;
uint flag_mask = SKF_FREEBIND;
/* FIXME: Add some global init? */
if (!bgp_linpool)
@ -165,8 +167,11 @@ bgp_open(struct bgp_proto *p)
/* We assume that cf->iface is defined iff cf->local_ip is link-local */
WALK_LIST(bs, bgp_sockets)
if (ipa_equal(bs->sk->saddr, addr) && (bs->sk->sport == port) &&
(bs->sk->iface == ifa) && (bs->sk->vrf == p->p.vrf))
if (ipa_equal(bs->sk->saddr, addr) &&
(bs->sk->sport == port) &&
(bs->sk->iface == ifa) &&
(bs->sk->vrf == p->p.vrf) &&
((bs->sk->flags & flag_mask) == flags))
{
bs->uc++;
p->sock = bs;
@ -180,7 +185,7 @@ bgp_open(struct bgp_proto *p)
sk->sport = port;
sk->iface = ifa;
sk->vrf = p->p.vrf;
sk->flags = 0;
sk->flags = flags;
sk->tos = IP_PREC_INTERNET_CONTROL;
sk->rbsize = BGP_RX_BUFFER_SIZE;
sk->tbsize = BGP_TX_BUFFER_SIZE;

1
proto/bgp/bgp.h
View file

@ -86,6 +86,7 @@ struct bgp_config {
int peer_type; /* Internal or external BGP (BGP_PT_*, optional) */
int multihop; /* Number of hops if multihop */
int strict_bind; /* Bind listening socket to local address */
int free_bind; /* Bind listening socket with SKF_FREEBIND */
int ttl_security; /* Enable TTL security [RFC 5082] */
int compare_path_lengths; /* Use path lengths when selecting best route */
int med_metric; /* Compare MULTI_EXIT_DISC even between routes from differen ASes */

3
proto/bgp/config.Y
View file

@ -31,7 +31,7 @@ CF_KEYWORDS(BGP, LOCAL, NEIGHBOR, AS, HOLD, TIME, CONNECT, RETRY, KEEPALIVE,
STRICT, BIND, CONFEDERATION, MEMBER, MULTICAST, FLOW4, FLOW6, LONG,
LIVED, STALE, IMPORT, IBGP, EBGP, MANDATORY, INTERNAL, EXTERNAL, SETS,
DYNAMIC, RANGE, NAME, DIGITS, BGP_AIGP, AIGP, ORIGINATE, COST, ENFORCE,
FIRST)
FIRST, FREE)
%type <i> bgp_nh
%type <i32> bgp_afi
@ -155,6 +155,7 @@ bgp_proto:
}
| bgp_proto DYNAMIC NAME DIGITS expr ';' { BGP_CFG->dynamic_name_digits = $5; if ($5>10) cf_error("Dynamic name digits must be at most 10"); }
| bgp_proto STRICT BIND bool ';' { BGP_CFG->strict_bind = $4; }
| bgp_proto FREE BIND bool ';' { BGP_CFG->free_bind = $4; }
| bgp_proto PATH METRIC bool ';' { BGP_CFG->compare_path_lengths = $4; }
| bgp_proto MED METRIC bool ';' { BGP_CFG->med_metric = $4; }
| bgp_proto IGP METRIC bool ';' { BGP_CFG->igp_metric = $4; }