[PATCH] test: Fix spurious test failure with systemd-resolved

[PATCH] test: Fix spurious test failure with systemd-resolved

[David Gibson]

systemd-resolved has the rather strange behaviour of listening on the
non-standard loopback address 127.0.0.53.  Various changes we've made in
passt mean that we now usually work fine on a host using systemd-resolved.
However our tests still fail in this case.  We have a special case for when
the guest's resolv.conf needs to differ from the host's because the
resolver is on a host loopback address.  However, we only consider the case
where the host resolver is on 127.0.0.1, not other loopback addresses.

Correct this with a different test condition.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 test/passt/dhcp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/test/passt/dhcp b/test/passt/dhcp
index 3ec2faf2..e05a4bb1 100644
--- a/test/passt/dhcp
+++ b/test/passt/dhcp
@@ -38,7 +38,7 @@ check	[ __MTU__ = 65520 ]
 test	DHCP: DNS
 gout	DNS sed -n 's/^nameserver \([0-9]*\.\)\(.*\)/\1\2/p' /etc/resolv.conf | tr '\n' ',' | sed 's/,$//;s/$/\n/'
 hout	HOST_DNS sed -n 's/^nameserver \([0-9]*\.\)\(.*\)/\1\2/p' /etc/resolv.conf | head -n3 | tr '\n' ',' | sed 's/,$//;s/$/\n/'
-check	[ "__DNS__" = "__HOST_DNS__" ] || [ "__DNS__" = "__HOST_GW__" -a "__HOST_DNS__" = "127.0.0.1" ]
+check	[ "__DNS__" = "__HOST_DNS__" ] || ( [ "__DNS__" = "__HOST_GW__" ] && expr "__HOST_DNS__" : "127[.]" )
 
 # FQDNs should be terminated by dots, but the guest DHCP client might omit them:
 # strip them first
-- 
@@ -38,7 +38,7 @@ check	[ __MTU__ = 65520 ]
 test	DHCP: DNS
 gout	DNS sed -n 's/^nameserver \([0-9]*\.\)\(.*\)/\1\2/p' /etc/resolv.conf | tr '\n' ',' | sed 's/,$//;s/$/\n/'
 hout	HOST_DNS sed -n 's/^nameserver \([0-9]*\.\)\(.*\)/\1\2/p' /etc/resolv.conf | head -n3 | tr '\n' ',' | sed 's/,$//;s/$/\n/'
-check	[ "__DNS__" = "__HOST_DNS__" ] || [ "__DNS__" = "__HOST_GW__" -a "__HOST_DNS__" = "127.0.0.1" ]
+check	[ "__DNS__" = "__HOST_DNS__" ] || ( [ "__DNS__" = "__HOST_GW__" ] && expr "__HOST_DNS__" : "127[.]" )
 
 # FQDNs should be terminated by dots, but the guest DHCP client might omit them:
 # strip them first
-- 
2.45.2

Re: [PATCH] test: Fix spurious test failure with systemd-resolved

[Stefano Brivio]

On Thu, 25 Jul 2024 16:50:42 +1000
David Gibson <david@gibson.dropbear.id.au> wrote:

> systemd-resolved has the rather strange behaviour of listening on the
> non-standard loopback address 127.0.0.53.  Various changes we've made in
> passt mean that we now usually work fine on a host using systemd-resolved.
> However our tests still fail in this case.  We have a special case for when
> the guest's resolv.conf needs to differ from the host's because the
> resolver is on a host loopback address.  However, we only consider the case
> where the host resolver is on 127.0.0.1, not other loopback addresses.
> 
> Correct this with a different test condition.
> 
> Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

Applied.

-- 
Stefano