Re: [PATCH 2/2] test: Improve test for NDP assigned prefix

[Stefano Brivio <sbrivio@redhat.com>]

On Wed,  6 Nov 2024 12:44:15 +1100
David Gibson <david@gibson.dropbear.id.au> wrote:

> In the NDP tests we search explicitly for a guest address with prefix
> length 64.  AFAICT this is an attempt to specifically find the SLAAC
> assigned address, rather than something assigned by other means.  We can do
> that more explicitly by checking for .protocol == "kernel_ra". however.
> 
> The SLAAC prefixes we assigned *will* always be 64-bit, that's hard-coded
> into our NDP implementation.  RFC4862 doesn't really allow anything else
> since the interface identifiers for an Ethernet-like link are 64-bits.
> 
> Let's actually verify that, rather than just assuming it, by extracting the
> prefix length assigned in the guest and checking it as well.
> 
> Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
> ---
>  test/passt/ndp | 4 ++--
>  test/pasta/ndp | 4 ++--
>  2 files changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/test/passt/ndp b/test/passt/ndp
> index f54b8ce..56b385b 100644
> --- a/test/passt/ndp
> +++ b/test/passt/ndp
> @@ -23,8 +23,8 @@ hout	HOST_IFNAME6 ip -j -6 route show|jq -rM '[.[] | select(.dst == "default").d
>  check	[ -n "__IFNAME__" ]
>  
>  test	SLAAC: prefix
> -gout	ADDR6 ip -j -6 addr show|jq -rM '[.[] | select(.ifname == "__IFNAME__").addr_info[] | select(.scope == "global" and .prefixlen == 64).local] | .[0]'
> -gout	PREFIX6 sipcalc __ADDR6__/64 | grep prefix | cut -d' ' -f4
> +gout	ADDR6 ip -j -6 addr show|jq -rM '[.[] | select(.ifname == "__IFNAME__").addr_info[] | select(.scope == "global" and .protocol == "kernel_ra") | .local + "/" + (.prefixlen | tostring)] | .[0]'

This makes tests occasionally fail for me. The pasta/ndp tests is not
affected. __PREFIX6__ is empty because there are no addresses with
protocol "kernel_ra" when we check. If I do:

@@ -23,6 +23,7 @@ hout  HOST_IFNAME6 ip -j -6 route show|jq -rM '[.[] | select(.dst == "default").d
 check  [ -n "__IFNAME__" ]
 
 test   SLAAC: prefix
+sleep  2
 gout   ADDR6 ip -j -6 addr show|jq -rM '[.[] | select(.ifname == "__IFNAME__").addr_info[] | select(.scope == "global" and .protocol == "kernel_ra") | .local + "/" + (.prefixlen | tostring)] | .[0]'
 gout   PREFIX6 sipcalc __ADDR6__ | grep prefix | cut -d' ' -f4
 hout   HOST_ADDR6 ip -j -6 addr show|jq -rM '[.[] | select(.ifname == "__HOST_IFNAME6__").addr_info[] | select(.scope == "global" and .deprecated != true).local] | .[0]'

things seem to work, but I didn't test many times, and looking at
47f0bd503210 ("net: Add new protocol attribute to IP addresses"), I
don't see how that would help.

-- 
Stefano