BGP: support for addpath TX

Signed-off-by: Daniel Walton <dwalton@cumulusnetworks.com>
Reviewed-by:   Donald Sharp <sharpd@cumulusnetworks.com>
Reviewed-by:   Vivek Venkataraman <vivek@cumulusnetworks.com

Ticket: CM-8014

This implements addpath TX with the first feature to use it
being "neighbor x.x.x.x addpath-tx-all-paths".

One change to show output is 'show ip bgp x.x.x.x'.  If no addpath-tx
features are configured for any peers then everything looks the same
as it is today in that "Advertised to" is at the top and refers to
which peers the bestpath was advertise to.

root@superm-redxp-05[quagga-stash5]# vtysh -c 'show ip bgp 1.1.1.1'
BGP routing table entry for 1.1.1.1/32
Paths: (6 available, best #6, table Default-IP-Routing-Table)
  Advertised to non peer-group peers:
  r1(10.0.0.1) r2(10.0.0.2) r3(10.0.0.3) r4(10.0.0.4) r5(10.0.0.5) r6(10.0.0.6) r8(10.0.0.8)
  Local, (Received from a RR-client)
    12.12.12.12 (metric 20) from r2(10.0.0.2) (10.0.0.2)
      Origin IGP, metric 0, localpref 100, valid, internal
      AddPath ID: RX 0, TX 8
      Last update: Fri Oct 30 18:26:44 2015
[snip]

but once you enable an addpath feature we must display "Advertised to" on a path-by-path basis:

superm-redxp-05# show ip bgp 1.1.1.1/32
BGP routing table entry for 1.1.1.1/32
Paths: (6 available, best #6, table Default-IP-Routing-Table)
  Local, (Received from a RR-client)
    12.12.12.12 (metric 20) from r2(10.0.0.2) (10.0.0.2)
      Origin IGP, metric 0, localpref 100, valid, internal
      AddPath ID: RX 0, TX 8
      Advertised to: r8(10.0.0.8)
      Last update: Fri Oct 30 18:26:44 2015

  Local, (Received from a RR-client)
    34.34.34.34 (metric 20) from r3(10.0.0.3) (10.0.0.3)
      Origin IGP, metric 0, localpref 100, valid, internal
      AddPath ID: RX 0, TX 7
      Advertised to: r8(10.0.0.8)
      Last update: Fri Oct 30 18:26:39 2015

  Local, (Received from a RR-client)
    56.56.56.56 (metric 20) from r6(10.0.0.6) (10.0.0.6)
      Origin IGP, metric 0, localpref 100, valid, internal
      AddPath ID: RX 0, TX 6
      Advertised to: r8(10.0.0.8)
      Last update: Fri Oct 30 18:26:39 2015

  Local, (Received from a RR-client)
    56.56.56.56 (metric 20) from r5(10.0.0.5) (10.0.0.5)
      Origin IGP, metric 0, localpref 100, valid, internal
      AddPath ID: RX 0, TX 5
      Advertised to: r8(10.0.0.8)
      Last update: Fri Oct 30 18:26:39 2015

  Local, (Received from a RR-client)
    34.34.34.34 (metric 20) from r4(10.0.0.4) (10.0.0.4)
      Origin IGP, metric 0, localpref 100, valid, internal
      AddPath ID: RX 0, TX 4
      Advertised to: r8(10.0.0.8)
      Last update: Fri Oct 30 18:26:39 2015

  Local, (Received from a RR-client)
    12.12.12.12 (metric 20) from r1(10.0.0.1) (10.0.0.1)
      Origin IGP, metric 0, localpref 100, valid, internal, best
      AddPath ID: RX 0, TX 3
      Advertised to: r1(10.0.0.1) r2(10.0.0.2) r3(10.0.0.3) r4(10.0.0.4) r5(10.0.0.5) r6(10.0.0.6) r8(10.0.0.8)
      Last update: Fri Oct 30 18:26:34 2015

superm-redxp-05#

1 files changed, 14 insertions, 15 deletions

diff --git a/bgpd/bgp_advertise.c b/bgpd/bgp_advertise.c
index 70d878739..73b2619c2 100644
--- a/bgpd/bgp_advertise.c
+++ b/bgpd/bgp_advertise.c
@@ -155,30 +155,29 @@ bgp_advertise_unintern (struct hash *hash, struct bgp_advertise_attr *baa)
     }
 }
 
-struct bgp_adj_out *
-bgp_adj_peer_lookup (struct peer *peer, struct bgp_node *rn)
-{
-  struct bgp_adj_out *adj;
-  struct peer_af *paf;
-
-  for (adj = rn->adj_out; adj; adj = adj->next)
-    SUBGRP_FOREACH_PEER(adj->subgroup, paf)
-      if (paf->peer == peer)
-	return adj;
-  return NULL;
-}
-
 int
-bgp_adj_out_lookup (struct peer *peer, struct prefix *p,
-		    afi_t afi, safi_t safi, struct bgp_node *rn)
+bgp_adj_out_lookup (struct peer *peer, struct bgp_node *rn,
+                    u_int32_t addpath_tx_id)
 {
   struct bgp_adj_out *adj;
   struct peer_af *paf;
+  afi_t afi;
+  safi_t safi;
+  int addpath_capable;
 
   for (adj = rn->adj_out; adj; adj = adj->next)
     SUBGRP_FOREACH_PEER(adj->subgroup, paf)
       if (paf->peer == peer)
 	{
+          afi = SUBGRP_AFI (adj->subgroup);
+          safi = SUBGRP_SAFI (adj->subgroup);
+          addpath_capable = bgp_addpath_encode_tx (peer, afi, safi);
+
+          /* Match on a specific addpath_tx_id if we are using addpath for this
+           * peer and if an addpath_tx_id was specified */
+          if (addpath_capable && addpath_tx_id && adj->addpath_tx_id != addpath_tx_id)
+            continue;
+
 	  return (adj->adv
 		  ? (adj->adv->baa ? 1 : 0)
 		  : (adj->attr ? 1 : 0));