[FUG-BR] OpenBGP allowas-in

[eksffa em freebsdbrasil.com.br]

Botei a feature no OpenBGP. O patch[1] funciona OK no OpenBSD tambem,
alem do FreeBSD claro (e ate aplicou na versão do Linux mas como n
uso, só vi que aplicou clean...). Se alguem preferir usar direto no
ports ao invés de aplicar o patch na mão o diff está pronto[2] pra
enviar um PR pro ports também, mas vou enviar depois de 1 semana de
testes. 
Todo teste é bem-vindo.

[1]http://main.bh.freebsdbrasil.com.br/~eksffa/l/local-patch-openbgpd-allowas-in.c[2]http://main.bh.freebsdbrasil.com.br/~eksffa/l/ports_net_openbgpd-allowas-in.diff

	Allow the AS path of a received route to contain the recipient BGP
speaker's AS number any number of times, avoiding Route Decision
Engine loop prevention for this peer. This is a feature that should
rarely be needed. Usually the need for this feature suggests something
wrong on the current BGP setup. However in some particular setups it's
just needed, and can be used without breaking BGP or adding loops.
Cisco, Juniper and other BGP routing daemons do offer the same
feature, sometimes with explicit control of how many times the AS
number is accepted in the as-path. It does not help, the wrong setup
will loop anyway, therefore we just allow it any number of times. On
bgpd.conf(5), use it on a per neighbor/group basis: group "my_peers" {
allowas-in (...) neighbor $a_peer { (...) allowas-in } } Shamely, I
didn't patch bgpd.conf(5), therefore it's more than welcome. --
Patrick Tracanelli  diff -ur bgpctl/parser.h ~proapps/bgpctl/parser.h
--- bgpctl/parser.h 2015-01-23 23:31:01.577342975 -0200 +++
bgpctl/parser.h 2015-01-23 23:24:28.597360000 -0200 @@ -44,6 +44,7 @@
NEIGHBOR, NEIGHBOR_UP, NEIGHBOR_DOWN, + ASIN, NEIGHBOR_CLEAR,
NEIGHBOR_RREFRESH, NETWORK_ADD, diff -ur bgpd/bgpd.h
~proapps/bgpd/bgpd.h --- bgpd/bgpd.h 2015-01-23 23:31:01.607382547
-0200 +++ ~proapps/bgpd/bgpd.h 2015-01-23 23:33:55.404600629 -0200 @@
-88,6 +88,7 @@ #define F_CTL_ADJ_IN 0x2000 #define F_CTL_ADJ_OUT
0x4000 #define F_CTL_ACTIVE 0x8000 +#define F_ASIN 0x9000 /* * Limit
the number of control messages generated by the RDE and queued in @@
-307,6 +308,7 @@ u_int8_t distance; /* 1 = direct, >1 = multihop */
u_int8_t passive; u_int8_t down; + u_int8_t asin; u_int8_t
announce_capa; u_int8_t reflector_client; u_int8_t softreconfig_in;
diff -ur bgpd/parse.y ~proapps/bgpd/parse.y --- bgpd/parse.y
2015-01-23 23:31:01.678126734 -0200 +++ ~proapps/bgpd/parse.y
2015-01-23 23:20:44.100628000 -0200 @@ -174,7 +174,7 @@ %token GROUP
NEIGHBOR NETWORK %token REMOTEAS DESCR LLIFACE LOCALADDR MULTIHOP
PASSIVE MAXPREFIX RESTART %token ANNOUNCE CAPABILITIES REFRESH AS4BYTE
CONNECTRETRY -%token DEMOTE ENFORCE NEIGHBORAS REFLECTOR DEPEND DOWN
SOFTRECONFIG +%token DEMOTE ENFORCE NEIGHBORAS REFLECTOR DEPEND DOWN
ASIN SOFTRECONFIG %token DUMP IN OUT SOCKET RESTRICTED %token LOG
ROUTECOLL TRANSPARENT %token TCP MD5SIG PASSWORD KEY TTLSECURITY @@
-995,6 +995,9 @@ | DOWN { curpeer->conf.down = 1; } + | ASIN { +
curpeer->conf.asin = 1; + } | RIB STRING { if (!find_rib($2)) {
yyerror("rib "%s" does not exist.", $2); @@ -2149,6 +2152,7 @@ {
"IPv6", IPV6}, { "ah", AH}, { "allow", ALLOW}, + { "allowas-in",
ASIN}, { "announce", ANNOUNCE}, { "any", ANY}, { "as-4byte", AS4BYTE
}, diff -ur bgpd/printconf.c ~proapps/bgpd/printconf.c ---
bgpd/printconf.c 2015-01-23 23:31:01.697349009 -0200 +++
~proapps/bgpd/printconf.c 2015-01-23 23:21:45.037370000 -0200 @@
-360,6 +360,8 @@ printf("%stremote-as %sn", c, log_as(p->remote_as));
if (p->down) printf("%stdownn", c); + if (p->asin) +
printf("%stallowas-inn", c); if (p->distance > 1) printf("%stmultihop
%un", c, p->distance); if (p->passive) diff -ur bgpd/rde.c
~proapps/bgpd/rde.c --- bgpd/rde.c 2015-01-23 23:31:01.707337429 -0200
+++ ~proapps/bgpd/rde.c 2015-01-23 23:26:54.317349000 -0200 @@ -1177,8
+1177,8 @@ /* shift to NLRI information */ p += 2 + attrpath_len; - /*
aspath needs to be loop free nota bene this is not a hard error */ -
if (peer->conf.ebgp && !aspath_loopfree(asp->aspath, conf->as)) + /*
unless allowas-in, aspath needs to be loop free nota bene this is not
a hard error */ + if (peer->conf.ebgp && !peer->conf.asin &&
!aspath_loopfree(asp->aspath, conf->as)) asp->flags |= F_ATTR_LOOP; /*
parse nlri prefix */
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