Use DNS and proxy settings from first interface with an IPv4 address

Instead of always preferring en0.

Signed-off-by: Jan Dubois <[email protected]>

Author: jandubois

docs/network.md

@@ -40,7 +40,7 @@ DNS over tcp is rarely used. It is usually only used either when user explicitly
 
 During initial cloud-init bootstrap, `iptables` may not yet be installed. In that case the repo server is determined using the slirp DNS. After `iptables` has been installed, the forwarding rule is applied, switching over to the hostagent DNS.
 
-If `useHostResoler` is false, then DNS servers can be configured manually in `lima.yaml` via the `dns` setting. If that list is empty, then Lima will either use the slirp DNS (on Linux), or the nameservers from the `en0` host interface (on macOS).
+If `useHostResoler` is false, then DNS servers can be configured manually in `lima.yaml` via the `dns` setting. If that list is empty, then Lima will either use the slirp DNS (on Linux), or the nameservers from the first host interface in service order that has an assigned IPv4 address (on macOS).
 
 ## `vde_vmnet` (192.168.105.0/24)
 

pkg/limayaml/default.yaml

@@ -252,9 +252,10 @@ hostResolver:
 # If useHostResolver is false, then the following rules apply for configuring dns:
 # Explicitly set DNS addresses for qemu user-mode networking. By default qemu picks *one*
 # nameserver from the host config and forwards all queries to this server. On macOS
-# Lima adds the nameservers configured for the "en0" interface to the list. In case this
-# still doesn't work (e.g. VPN setups), the servers can be specified here explicitly.
-# If nameservers are specified here, then the "en0" configuration will be ignored.
+# Lima adds the nameservers configured for the first host interface in service order,
+# that has an IPv4 address, to the list. In case this still doesn't work (e.g. VPN
+# setups), the servers can be specified here explicitly. If nameservers are specified
+# here, then the configuration from network preferences will be ignored.
 # dns:
 # - 1.1.1.1
 # - 1.0.0.1

pkg/osutil/dns_darwin.go

@@ -14,17 +14,14 @@ func DNSAddresses() ([]string, error) {
 	}
 	var addresses []string
 	if len(nwData) > 0 {
-		// Return DNS addresses from en0 interface
+		// Return DNS addresses from the first interface that has an IPv4 address.
+		// The networks are in service order already.
 		for _, nw := range nwData {
-			if nw.Interface == "en0" {
+			if len(nw.IPv4.Addresses) > 0 {
 				addresses = nw.DNS.ServerAddresses
 				break
 			}
 		}
-		// In case "en0" is not found, use the addresses of the first interface
-		if len(addresses) == 0 {
-			addresses = nwData[0].DNS.ServerAddresses
-		}
 	}
 	return addresses, nil
 }
@@ -48,10 +45,11 @@ func ProxySettings() (map[string]string, error) {
 	}
 	env := make(map[string]string)
 	if len(nwData) > 0 {
-		// In case "en0" is not found, use the proxies of the first interface
-		proxies := nwData[0].Proxies
+		// Return proxy settings from the first interface that has an IPv4 address.
+		// The networks are in service order already.
+		var proxies sysprof.Proxies
 		for _, nw := range nwData {
-			if nw.Interface == "en0" {
+			if len(nw.IPv4.Addresses) > 0 {
 				proxies = nw.Proxies
 				break
 			}

pkg/sysprof/network_darwin.go

@@ -7,13 +7,18 @@ type SPNetworkDataType struct {
 type NetworkDataType struct {
 	DNS       DNS     `json:"DNS"`
 	Interface string  `json:"interface"`
+	IPv4      IPv4    `json:"IPv4,omitempty"`
 	Proxies   Proxies `json:"Proxies"`
 }
 
 type DNS struct {
 	ServerAddresses []string `json:"ServerAddresses"`
 }
 
+type IPv4 struct {
+	Addresses []string `json:"Addresses,omitempty"`
+}
+
 type Proxies struct {
 	ExceptionList []string    `json:"ExceptionList"` // default: ["*.local", "169.254/16"]
 	FTPEnable     string      `json:"FTPEnable"`