[PATCH RFC installer 6/8] sys: net: ignore ipv6 nameservers with zone identifiers

[Christoph Heiss <c.heiss@proxmox.com>]

The stack does not handle IPv6 addresses with zone identifiers anywhere
(yet).

Just dropping the zone identifier would be another possibility for now,
but would probably break more things (as they are e.g. pretty much
mandantory for link-local addresses.)

IPv6 addresses with zone identifiers are not all that well supported and
are uncommon anyway it seems, see [0][1][2].

For now, work around that by ignoring all IPv6 nameservers with zone
identifiers.

[0] https://github.com/containers/common/pull/2233
[1] https://github.com/containers/aardvark-dns/issues/535
[2] https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=255316

Signed-off-by: Christoph Heiss <c.heiss@proxmox.com>
---
Sending as RFC as it is a rather ugly hack, but reworking the rest of
the stack is a bit more effort and wanted to send the series now.

Mainly fails due to parsing it as a `std::net::IpAddr` addresses in
Rust, which does not support zone identifiers, in addition to
Proxmox::Sys::Net::parse_ip_address() not recognizing them either.

 Proxmox/Sys/Net.pm | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/Proxmox/Sys/Net.pm b/Proxmox/Sys/Net.pm
index c6bd841..4781e51 100644
--- a/Proxmox/Sys/Net.pm
+++ b/Proxmox/Sys/Net.pm
@@ -334,7 +334,14 @@ sub query_dns : prototype() {
     my $domain;
     while (defined(my $line = <$fh>)) {
         if ($line =~ /^nameserver\s+(\S+)/) {
-            push @dns, $1;
+            # FIXME: handle IPv6 zone identifiers across the stack.
+            # For now, ignore all addresses containing them.
+            my $addr = $1;
+            if ($addr =~ /%\S+$/) {
+                log_warn("skipping nameserver $addr as being link-local");
+            } else {
+                push @dns, $addr;
+            }
         } elsif (!defined($domain) && $line =~ /^domain\s+(\S+)/) {
             $domain = $1;
         }
-- 
2.53.0