*: support replace-peer-as (aka as-override)

we use the term replace-peer-as instead of as-override
since openconfig is using it.

cli

```
$ gobgp n add <neighbor-addr> as <asn> replace-peer-as
```

config

```
neighbor:
  config:
    peer-as: <asn>
    neighbor-address: <neighbor-addr>
  as-path-options:
    config:
      replace-peer-as: true
```

Signed-off-by: Wataru Ishida <ishida.wataru@lab.ntt.co.jp>

1 files changed, 14 insertions, 0 deletions

diff --git a/table/path_test.go b/table/path_test.go
index 29a296ac..ea4e23d5 100644
--- a/table/path_test.go
+++ b/table/path_test.go
@@ -353,3 +353,17 @@ func TestRemovePrivateAS(t *testing.T) {
 	assert.Equal(t, list[2], uint32(1))
 	assert.Equal(t, list[3], uint32(2))
 }
+
+func TestReplaceAS(t *testing.T) {
+	aspathParam := []bgp.AsPathParamInterface{bgp.NewAs4PathParam(2, []uint32{64512, 64513, 1, 2})}
+	aspath := bgp.NewPathAttributeAsPath(aspathParam)
+	nlri := bgp.NewIPAddrPrefix(24, "30.30.30.0")
+	path := NewPath(nil, nlri, false, []bgp.PathAttributeInterface{aspath}, time.Now(), false)
+	path = path.ReplaceAS(10, 1)
+	list := path.GetAsList()
+	assert.Equal(t, len(list), 4)
+	assert.Equal(t, list[0], uint32(64512))
+	assert.Equal(t, list[1], uint32(64513))
+	assert.Equal(t, list[2], uint32(10))
+	assert.Equal(t, list[3], uint32(2))
+}