frr.conf

! SPDX-License-Identifier: ISC
!
! r1 — router under test
!
! Topology:
!   r1 ---eth0-eth0--- r2
!
! r1 receives 2600:1000::101/128 from r2 via IPv6 VPN with SRv6 encap and
! imports it into vrf test1.  A local static IPv4 route for 198.0.0.150/32
! points at that IPv6 nexthop, triggering the recursive resolution code path
! in nexthop_set_resolved() that the fix targets.
!
hostname r1
!
interface lo
 ipv6 address 2001:db8:1:1::1/128
!
interface eth0
 ipv6 address 2001:db8:12::1/64
!
segment-routing
 srv6
  locators
   locator loc1
    prefix 2001:db8:1:1::/64 block-len 40 node-len 24 func-bits 16
   !
  !
 !
!
ip forwarding
ipv6 forwarding
!
! Underlay reachability to r2's loopback (VPN BGP nexthop)
ipv6 route 2001:db8:2:2::/64 2001:db8:12::2
!
! Underlay reachability to r2's SRv6 locator (needed for kernel to forward SRv6 packets)
ipv6 route 2001:db8:3::/48 2001:db8:12::2
!
! The IPv4 route under test: NH is an IPv6 address only reachable via the
! SRv6 VPN route imported into vrf test1.  No SRv6 SID is associated with
! this static route — its nexthop->nh_srv6 is NULL — which is exactly the
! condition that exposed the bug.
ip route 198.0.0.150/32 2600:1000::101 vrf test1
!
line vty
!
router bgp 65001
 bgp router-id 1.1.1.1
 no bgp ebgp-requires-policy
 no bgp default ipv4-unicast
 neighbor 2001:db8:12::2 remote-as 65002
 neighbor 2001:db8:12::2 timers 3 10
 neighbor 2001:db8:12::2 timers connect 1
 neighbor 2001:db8:12::2 capability extended-nexthop
 !
 segment-routing srv6
  locator loc1
 !
 address-family ipv6 vpn
  neighbor 2001:db8:12::2 activate
 exit-address-family
!
router bgp 65001 vrf test1
 bgp router-id 1.1.1.1
 no bgp ebgp-requires-policy
 !
 address-family ipv6 unicast
  ! Import the SRv6 VPN route for 2600:1000::101/128 so the recursive
  ! nexthop of 198.0.0.150/32 can be resolved through it.
  rd vpn export 65001:10
  rt vpn both 0:20
  import vpn
 exit-address-family
!