Restore server network auto-detection

Signed-off-by: Jonathon Anderson <janderson@ciq.com>

internal/pkg/config/root.go

@@ -41,6 +41,7 @@ type WarewulfYaml struct {
 	WWClient    *WWClientConf `yaml:"wwclient,omitempty"`
 
 	warewulfconf string
+	autodetected bool
 }
 
 // New caches and returns a new [WarewulfYaml] initialized with empty
@@ -73,12 +74,12 @@ func Get() *WarewulfYaml {
 
 // Read populates [WarewulfYaml] with the values from a configuration
 // file.
-func (conf *WarewulfYaml) Read(confFileName string) error {
+func (conf *WarewulfYaml) Read(confFileName string, autodetect bool) error {
 	wwlog.Debug("Reading warewulf.conf from: %s", confFileName)
 	conf.warewulfconf = confFileName
 	if data, err := os.ReadFile(confFileName); err != nil {
 		return err
-	} else if err := conf.Parse(data); err != nil {
+	} else if err := conf.Parse(data, autodetect); err != nil {
 		return err
 	} else {
 		return nil
@@ -86,7 +87,7 @@ func (conf *WarewulfYaml) Read(confFileName string) error {
 }
 
 // Parse populates [WarewulfYaml] with the values from a yaml document.
-func (conf *WarewulfYaml) Parse(data []byte) error {
+func (conf *WarewulfYaml) Parse(data []byte, autodetect bool) error {
 	// ipxe binaries are merged not overwritten, store defaults separate
 	defIpxe := make(map[string]string)
 	for k, v := range conf.TFTP.IpxeBinaries {
@@ -110,6 +111,33 @@ func (conf *WarewulfYaml) Parse(data []byte) error {
 		}
 	}
 
+	if autodetect {
+		if conf.Ipaddr == "" {
+			if ip := GetOutboundIP(); ip != nil {
+				conf.Ipaddr = ip.String()
+				conf.autodetected = true
+			}
+		}
+
+		if conf.Netmask == "" {
+			if ip := net.ParseIP(conf.Ipaddr); ip != nil {
+				if network, err := GetIPNetForIP(ip); err == nil {
+					conf.Netmask = net.IP(network.Mask).String()
+					conf.autodetected = true
+				}
+			}
+		}
+
+		if conf.Network == "" {
+			if ip := net.ParseIP(conf.Ipaddr); ip != nil {
+				if mask := net.IPMask(net.ParseIP(conf.Netmask)); mask != nil {
+					conf.Network = ip.Mask(mask).String()
+					conf.autodetected = true
+				}
+			}
+		}
+	}
+
 	if conf.Ipaddr6 != "" {
 		if _, network, err := net.ParseCIDR(conf.Ipaddr6); err == nil {
 			if conf.Ipv6net == "" {
@@ -161,6 +189,10 @@ func (conf *WarewulfYaml) GetWarewulfConf() string {
 	return conf.warewulfconf
 }
 
+func (conf *WarewulfYaml) Autodetected() bool {
+	return conf.autodetected
+}
+
 func (config *WarewulfYaml) Dump() ([]byte, error) {
 	var buf bytes.Buffer
 	yamlEncoder := yaml.NewEncoder(&buf)

internal/pkg/config/root_test.go

@@ -385,7 +385,7 @@ tftp:
 	for name, tt := range tests {
 		t.Run(name, func(t *testing.T) {
 			conf := New()
-			err := conf.Parse([]byte(tt.input))
+			err := conf.Parse([]byte(tt.input), false)
 			assert.NoError(t, err)
 			result, err := conf.Dump()
 			assert.NoError(t, err)
@@ -405,7 +405,7 @@ func TestInitializedFromFile(t *testing.T) {
 
 	conf := New()
 	assert.False(t, conf.InitializedFromFile())
-	assert.NoError(t, conf.Read(tempWarewulfConf.Name()))
+	assert.NoError(t, conf.Read(tempWarewulfConf.Name(), false))
 	assert.True(t, conf.InitializedFromFile())
 	assert.Equal(t, conf.GetWarewulfConf(), tempWarewulfConf.Name())
 }

internal/pkg/config/util.go

@@ -1,5 +1,62 @@
 package config
 
+import (
+	"fmt"
+	"net"
+)
+
 func BoolP(p *bool) bool {
 	return p != nil && *p
 }
+
+func GetOutboundIP() net.IP {
+	conn, err := net.Dial("udp", "192.0.2.1:80")
+	if err != nil {
+		return nil
+	}
+	defer conn.Close()
+	localAddr := conn.LocalAddr().(*net.UDPAddr)
+	return localAddr.IP
+}
+
+func GetIPNetForIP(ip net.IP) (*net.IPNet, error) {
+	interfaces, err := net.Interfaces()
+	if err != nil {
+		return nil, fmt.Errorf("failed to get network interfaces: %v", err)
+	}
+
+	for _, iface := range interfaces {
+		// skip interfaces that are down or not relevant
+		if iface.Flags&net.FlagUp == 0 {
+			continue
+		}
+
+		addrs, err := iface.Addrs()
+		if err != nil {
+			continue // try next interface
+		}
+
+		for _, addr := range addrs {
+			// We expect addr to be of type *net.IPNet.
+			var ipNet *net.IPNet
+			switch v := addr.(type) {
+			case *net.IPNet:
+				ipNet = v
+			case *net.IPAddr:
+				// Wrap net.IPAddr in an IPNet with its default mask.
+				ipNet = &net.IPNet{IP: v.IP, Mask: v.IP.DefaultMask()}
+			}
+
+			if ipNet == nil {
+				continue
+			}
+
+			// Check if the IP matches (for IPv4, Equal works well)
+			if ipNet.IP.Equal(ip) {
+				return ipNet, nil
+			}
+		}
+	}
+
+	return nil, fmt.Errorf("could not find IPNet for IP %v", ip)
+}