[PATCH installer 7/8] common: options: rework network address setup to handle ipv6-only

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

With this, IPv6-only setups are now handled properly. Previously it
would fail to actually select IPv6 addresses for the interface and DNS
on such setups, instead falling back to the default IPv4 addresses set
above.

Signed-off-by: Christoph Heiss <c.heiss@proxmox.com>
---
 proxmox-installer-common/src/options.rs | 89 ++++++++++++-------------
 1 file changed, 44 insertions(+), 45 deletions(-)

diff --git a/proxmox-installer-common/src/options.rs b/proxmox-installer-common/src/options.rs
index ed00b4b..8929bd4 100644
--- a/proxmox-installer-common/src/options.rs
+++ b/proxmox-installer-common/src/options.rs
@@ -425,59 +425,58 @@ impl NetworkOptions {
             pinning_opts: pinning_opts.cloned(),
         };
 
-        if let Some(ip) = network.dns.dns.first() {
-            this.dns_server = *ip;
-        }
-
-        if let Some(routes) = &network.routes
-            && let Some(gw) = &routes.gateway4
-            && let Some(iface) = network.interfaces.get(&gw.dev)
-        {
-            // we got some ipv4 connectivity, so use that
-
-            if let Some(opts) = pinning_opts
-                && let Some(pinned) = iface.to_pinned(opts)
-            {
-                this.ifname.clone_from(&pinned.name);
-            } else {
-                this.ifname.clone_from(&iface.name);
-            }
-
-            if let Some(addr) = iface.addresses.iter().find(|addr| addr.is_ipv4()) {
-                this.gateway = gw.gateway;
-                this.address = *addr;
-            } else if let Some(gw) = &routes.gateway6
+        let iface = if let Some(routes) = &network.routes {
+            if let Some(gw) = &routes.gateway4
                 && let Some(iface) = network.interfaces.get(&gw.dev)
-                && let Some(addr) = iface.addresses.iter().find(|addr| addr.is_ipv6())
             {
-                // no ipv4, but ipv6 connectivity
-                if let Some(opts) = pinning_opts
-                    && let Some(pinned) = iface.to_pinned(opts)
-                {
-                    this.ifname.clone_from(&pinned.name);
-                } else {
-                    this.ifname.clone_from(&iface.name);
+                this.gateway = gw.gateway;
+
+                if let Some(addr) = iface.addresses.iter().find(|addr| addr.is_ipv4()) {
+                    this.address = *addr;
                 }
 
-                this.gateway = gw.gateway;
-                this.address = *addr;
-            }
-        }
+                if let Some(addr) = network.dns.dns.iter().find(|addr| addr.is_ipv4()) {
+                    this.dns_server = *addr;
+                }
 
-        // In case no there are no routes defined at all (e.g. no DHCP lease),
-        // try to set the interface name to *some* valid values. At least one
-        // NIC should always be present here, as the installation will abort
-        // earlier in that case, so use the first one enumerated.
-        if this.ifname.is_empty()
-            && let Some(iface) = network.interfaces.values().min_by_key(|v| v.index)
-        {
-            if let Some(opts) = pinning_opts
-                && let Some(pinned) = iface.to_pinned(opts)
+                Some(iface)
+            } else if let Some(gw) = &routes.gateway6
+                && let Some(iface) = network.interfaces.get(&gw.dev)
             {
-                this.ifname.clone_from(&pinned.name);
+                this.gateway = gw.gateway;
+
+                if let Some(addr) = iface.addresses.iter().find(|addr| addr.is_ipv6()) {
+                    this.address = *addr;
+                }
+
+                if let Some(addr) = network.dns.dns.iter().find(|addr| addr.is_ipv6()) {
+                    this.dns_server = *addr;
+                }
+
+                Some(iface)
             } else {
-                this.ifname.clone_from(&iface.name);
+                None
             }
+        } else {
+            None
+        }
+        .unwrap_or_else(|| {
+            // Safety: In case no there are no routes defined at all (e.g. no DHCP lease), try to
+            // set the interface name to *some* valid values. At least one NIC must always be
+            // present here, as the installation will abort earlier otherwise, so use the first one
+            // enumerated.
+            network
+                .interfaces
+                .values()
+                .min_by_key(|v| v.index)
+                .expect("at least one NIC must be present")
+        });
+
+        // Use pinned network interface name, if enabled
+        if let Some(pinned) = pinning_opts.and_then(|opts| iface.to_pinned(opts)) {
+            this.ifname.clone_from(&pinned.name);
+        } else {
+            this.ifname.clone_from(&iface.name);
         }
 
         if let Some(ref mut opts) = this.pinning_opts {
-- 
2.53.0