Allows to configure different remote port for BGP sessions.

Thanks to João Taveira Araújo for the original patch.

conf/confbase.Y

@@ -72,7 +72,7 @@ CF_DECLS
 %token <t> TEXT
 %type <iface> ipa_scope
 
-%type <i> expr bool pxlen
+%type <i> expr bool pxlen ipa_port
 %type <i32> expr_us
 %type <time> datetime
 %type <a> ipa
@@ -88,7 +88,7 @@ CF_DECLS
 %left '!'
 %nonassoc '.'
 
-CF_KEYWORDS(DEFINE, ON, OFF, YES, NO, S, MS, US)
+CF_KEYWORDS(DEFINE, ON, OFF, YES, NO, S, MS, US, PORT)
 
 CF_GRAMMAR
 
@@ -161,6 +161,14 @@ ipa_scope:
  | '%' SYM { $$ = if_get_by_name($2->name); }
  ;
 
+ipa_port:
+   /* empty */ { $$ = 0; }
+ | PORT expr {
+     if (($2 < 1) || ($2 > 65535)) cf_error("Invalid port number");
+     $$ = $2;
+   }
+ ;
+
 prefix:
    ipa pxlen {
      if (!ip_is_prefix($1, $2)) cf_error("Invalid prefix");

doc/bird.sgml

@@ -1004,7 +1004,6 @@ foot).
 	So <cf>1.2.0.0/16.pxlen = 16</cf> is true.
 
 	<tag/ec/
-
 	This is a specialized type used to represent BGP extended community
 	values. It is essentially a 64bit value, literals of this type are
 	usually written as <cf>(<m/kind/, <m/key/, <m/value/)</cf>, where
@@ -1616,7 +1615,7 @@ using the following configuration parameters:
 	address, equivalent to the <cf/source address/ option (see below). This
 	parameter is mandatory.
 
-	<tag>neighbor <m/ip/ as <m/number/</tag>
+	<tag>neighbor <m/ip/ [port <m/number/] as <m/number/</tag>
 	Define neighboring router this instance will be talking to and what AS
 	it's located in. In case the neighbor is in the same AS as we are, we
 	automatically switch to iBGP. This parameter is mandatory.

proto/bgp/bgp.c

@@ -680,8 +680,8 @@ bgp_connect(struct bgp_proto *p)	/* Enter Connect state and start establishing c
   s->type = SK_TCP_ACTIVE;
   s->saddr = p->source_addr;
   s->daddr = p->cf->remote_ip;
+  s->dport = p->cf->remote_port;
   s->iface = p->neigh ? p->neigh->iface : NULL;
-  s->dport = BGP_PORT;
   s->ttl = p->cf->ttl_security ? 255 : hops;
   s->rbsize = BGP_RX_BUFFER_SIZE;
   s->tbsize = BGP_TX_BUFFER_SIZE;
@@ -1016,9 +1016,9 @@ bgp_start(struct proto *P)
 
   lock = p->lock = olock_new(P->pool);
   lock->addr = p->cf->remote_ip;
+  lock->port = p->cf->remote_port;
   lock->iface = p->cf->iface;
   lock->type = OBJLOCK_TCP;
-  lock->port = BGP_PORT;
   lock->hook = bgp_start_locked;
   lock->data = p;
   olock_acquire(lock);

proto/bgp/bgp.h

@@ -23,6 +23,7 @@ struct bgp_config {
   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 */

proto/bgp/config.Y

@@ -60,7 +60,7 @@ bgp_proto:
  | bgp_proto proto_item ';'
  | bgp_proto LOCAL AS expr ';' { BGP_CFG->local_as = $4; }
  | bgp_proto LOCAL ipa AS expr ';' { BGP_CFG->source_addr = $3; BGP_CFG->local_as = $5; }
- | bgp_proto NEIGHBOR ipa ipa_scope AS expr ';' {
+ | bgp_proto NEIGHBOR ipa ipa_scope ipa_port AS expr ';' {
      if (ipa_nonzero(BGP_CFG->remote_ip))
        cf_error("Only one neighbor per BGP instance is allowed");
      if (!ipa_has_link_scope($3) != !$4)
@@ -68,7 +68,8 @@ bgp_proto:
 
      BGP_CFG->remote_ip = $3;
      BGP_CFG->iface = $4;
-     BGP_CFG->remote_as = $6;
+     BGP_CFG->remote_port = ($5 > 0) ? $5 : BGP_PORT;
+     BGP_CFG->remote_as = $7;
    }
  | bgp_proto RR CLUSTER ID idval ';' { BGP_CFG->rr_cluster_id = $5; }
  | bgp_proto RR CLIENT ';' { BGP_CFG->rr_client = 1; }