BGP add path support

[natesales]

With add-path receive enabled, rustybgp correctly detects that a peer is advertising the ADD-PATH capability, but doesn't import multiple routes:

Neighbor capabilities:
  multiprotocol:
    ipv4-unicast:   advertised and received
  route-refresh:      received
  graceful-restart:   received
  4-octet-as: advertised and received
  add-path:   received
    Remote:
      ipv4-unicast:  send

Steps to reproduce

1. Create config file bgp.yml:

global:
  config:
    as: 65530
    router-id: 192.168.90.4
    port: 179

  apply-policy:
    config:
      default-import-policy: accept-route
      default-export-policy: reject-route

neighbors:
  - config:
      peer-as: 65530
      neighbor-address: 192.168.90.1
    add-paths:
      config:
        receive: true

2. Build and run rustybgp

git clone https://github.com/osrg/rustybgp
cd rustybgp
git reset --hard 9a94087b81679af2304d1523c1bbde822be7010b
cargo build --release
./target/release/rustybgpd -f bgp.yml

3. gobgp neigh and confirm only ~900k routes received

Using gobgp with the same config works correctly.

[fujita]

Please use per-family config style like

[[neighbors]]
  [neighbors.config]
    peer-as = 65002
    neighbor-address = "10.0.0.2"
    [[neighbors.afi-safis]]
      [neighbors.afi-safis.config]
        afi-safi-name = "ipv4-unicast"
      [neighbors.afi-safis.add-paths.config]
        receive = true
        send-max = 8

[fujita]

The latest code explicitly returns an error for global add path config.

[natesales]

Thanks - that config works great on gobgp but not rustybgp. Here's my new full config, which works great and receives additional paths under gobgp, but the same config under rustybgp is stuck in Idle with the peer reporting "required capability missing".

global:
  config:
    as: 34553
    router-id: 192.168.90.4
    port: 179

  apply-policy:
    config:
      default-import-policy: accept-route
      default-export-policy: reject-route

neighbors:
  - config:
      peer-as: 34553
      neighbor-address: 192.168.90.1
    afi-safis:
      - config:
          afi-safi-name: ipv4-unicast
        add-paths:
          config:
            receive: true

[fujita]

Can you share the pcap file? I need open messages from both (one is rustybgp, and another is what?)

[natesales]

The remote side is BIRD 2.0.7; admittedly an older version of BIRD, but given GoBGP works correctly I suspect an issue on the rustybgp side. See attached pcap

rustybgp-bird.tar.gz

[fujita]

Thanks!
I fixed the bug. Can you try the latest master?

[natesales]

Fantastic, works great now. Thanks for the quick fix!