From bba54bdaa14c1a4c13245548757b38a89531fd9b Mon Sep 17 00:00:00 2001
From: ISHIDA Wataru <ishida.wataru@lab.ntt.co.jp>
Date: Wed, 3 Aug 2016 04:27:33 +0000
Subject: skip asn negotiation for BGP unnumbered peers

since BGP unnumbered peers are typically trusted, skip asn negotiation
for easy configuration.

from configuration file:

```toml
[[neighbors]]
[[neighbors.config]]
neighbor-interface = "eth0"
```

from cli:

```
$ gobgp neighbor add interface eth0
```

Signed-off-by: ISHIDA Wataru <ishida.wataru@lab.ntt.co.jp>
---
 server/fsm.go | 24 +++++++++++++++++++++---
 1 file changed, 21 insertions(+), 3 deletions(-)

(limited to 'server/fsm.go')

diff --git a/server/fsm.go b/server/fsm.go
index e680f8ec..f623f399 100644
--- a/server/fsm.go
+++ b/server/fsm.go
@@ -474,9 +474,9 @@ func (h *FSMHandler) active() (bgp.FSMState, FsmStateReason) {
 				break
 			}
 			fsm.conn = conn
-			if fsm.pConf.Config.PeerType == config.PEER_TYPE_EXTERNAL {
+			if fsm.pConf.Config.PeerAs != 0 && fsm.pConf.Config.PeerType == config.PEER_TYPE_EXTERNAL {
 				ttl := 1
-				if fsm.pConf.EbgpMultihop.Config.Enabled == true {
+				if fsm.pConf.EbgpMultihop.Config.Enabled {
 					ttl = int(fsm.pConf.EbgpMultihop.Config.MultihopTtl)
 				}
 				if ttl != 0 {
@@ -844,11 +844,29 @@ func (h *FSMHandler) opensent() (bgp.FSMState, FsmStateReason) {
 				if m.Header.Type == bgp.BGP_MSG_OPEN {
 					fsm.recvOpen = m
 					body := m.Body.(*bgp.BGPOpen)
-					err := bgp.ValidateOpenMsg(body, fsm.pConf.Config.PeerAs)
+					peerAs, err := bgp.ValidateOpenMsg(body, fsm.pConf.Config.PeerAs)
 					if err != nil {
 						fsm.sendNotificationFromErrorMsg(err.(*bgp.MessageError))
 						return bgp.BGP_FSM_IDLE, FSM_INVALID_MSG
 					}
+
+					// ASN negotiation was skipped
+					if fsm.pConf.Config.PeerAs == 0 {
+						typ := config.PEER_TYPE_EXTERNAL
+						if fsm.peerInfo.LocalAS == peerAs {
+							typ = config.PEER_TYPE_INTERNAL
+						}
+						fsm.pConf.State.PeerType = typ
+						log.WithFields(log.Fields{
+							"Topic": "Peer",
+							"Key":   fsm.pConf.Config.NeighborAddress,
+							"State": fsm.state.String(),
+						}).Infof("skiped asn negotiation: peer-as: %d, peer-type: %s", peerAs, typ)
+					} else {
+						fsm.pConf.State.PeerType = fsm.pConf.Config.PeerType
+					}
+					fsm.pConf.State.PeerAs = peerAs
+					fsm.peerInfo.AS = peerAs
 					fsm.peerInfo.ID = body.ID
 					fsm.capMap, fsm.rfMap = open2Cap(body, fsm.pConf)
 
-- 
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