Add IPv6 and VLAN devices to the web UI and router-setup

The web UI lists physical and VLAN interfaces and takes a VLAN uplink as
a device name (enp2s0.1001); it has IPv6 checkboxes for the WAN and each
LAN. router-setup asks whether to create VLANs before WAN and LAN are
picked, and whether to enable IPv6. --config-only writes the
configuration without installing, which the setup test uses for a PPPoE
uplink on a VLAN.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AeFqV9dZrK6nipHkPfyM4F

pkgs/router-webui/settings.go

@@ -131,10 +131,10 @@ type Form struct {
 }
 
 type WANForm struct {
-	Interface     string
+	Interface     string // a device: "enp2s0", or "enp2s0.1001" for a VLAN
 	Type          string // "dhcp" or "pppoe"
+	IPv6          bool
 	PPPoEUser     string
-	PPPoEVLAN     string
 	PPPoEPassword string // write-only: empty keeps the stored one
 	PasswordSet   bool
 }
@@ -146,6 +146,7 @@ type LANForm struct {
 	Address   string
 	Prefix    string
 	Internet  bool
+	IPv6PD    bool // delegate the ISP's prefix to this LAN
 	DHCP      bool
 	PoolStart string
 	PoolEnd   string
@@ -162,10 +163,13 @@ func (s Settings) form() Form {
 		WAN: WANForm{
 			Interface: str(router, "wan", "interface"),
 			Type:      str(router, "wan", "ipv4", "type"),
+			IPv6:      boolean(router, false, "wan", "ipv6", "enable"),
 			PPPoEUser: str(router, "wan", "ipv4", "pppoe", "username"),
-			PPPoEVLAN: str(router, "wan", "ipv4", "pppoe", "vlan"),
 		},
 	}
+	if vlan := str(router, "wan", "ipv4", "pppoe", "vlan"); vlan != "" && f.WAN.Type == "pppoe" {
+		f.WAN.Interface += "." + vlan
+	}
 	if f.WAN.Type == "" {
 		f.WAN.Type = "dhcp"
 	}
@@ -188,6 +192,7 @@ func (s Settings) form() Form {
 			Address:   str(l, "ipv4", "address"),
 			Prefix:    str(l, "ipv4", "prefixLength"),
 			Internet:  boolean(l, false, "internet"),
+			IPv6PD:    boolean(l, false, "ipv6", "pd"),
 			DHCP:      boolean(l, true, "dhcp", "enable"),
 			PoolStart: str(l, "dhcp", "pool", "start"),
 			PoolEnd:   str(l, "dhcp", "pool", "end"),
@@ -229,6 +234,64 @@ func optionalInt(v string, lo, hi int) (int, bool, error) {
 	return n, true, nil
 }
 
+// splitVLAN splits "enp2s0.1001" into the interface and its VLAN ID; a name
+// without one has VLAN 0.
+func splitVLAN(dev string) (string, int) {
+	dev = strings.TrimSpace(dev)
+	i := strings.LastIndex(dev, ".")
+	if i <= 0 {
+		return dev, 0
+	}
+	id, err := strconv.Atoi(dev[i+1:])
+	if err != nil || id < 1 || id > 4094 {
+		return dev, 0
+	}
+	return dev[:i], id
+}
+
+// Device is a row of the interface list: a physical NIC or a VLAN on one.
+type Device struct {
+	Name string
+	Kind string // "physical" or "VLAN"
+	Role string // "WAN", "LAN lan", or ""
+}
+
+// devices lists the physical interfaces plus the VLAN devices the settings
+// use, each with the role it plays.
+func (f Form) devices(physical []string) []Device {
+	roles := map[string][]string{}
+	add := func(dev, role string) { roles[dev] = append(roles[dev], role) }
+	add(f.WAN.Interface, "WAN")
+	for _, l := range f.LANs {
+		if l.Name == "" || l.Remove {
+			continue
+		}
+		dev := l.Interface
+		if l.VLAN != "" {
+			dev += "." + l.VLAN
+		}
+		add(dev, "LAN "+l.Name)
+	}
+	names := slices.Clone(physical)
+	var vlans []string
+	for dev := range roles {
+		if _, id := splitVLAN(dev); id != 0 && !slices.Contains(names, dev) {
+			vlans = append(vlans, dev)
+		}
+	}
+	slices.Sort(vlans)
+	var out []Device
+	for _, n := range names {
+		out = append(out, Device{Name: n, Kind: "physical", Role: strings.Join(roles[n], ", ")})
+		for _, v := range vlans {
+			if parent, _ := splitVLAN(v); parent == n {
+				out = append(out, Device{Name: v, Kind: "VLAN", Role: strings.Join(roles[v], ", ")})
+			}
+		}
+	}
+	return out
+}
+
 func ipv4(v string) (netip.Addr, bool) {
 	a, err := netip.ParseAddr(strings.TrimSpace(v))
 	return a, err == nil && a.Is4()
@@ -250,11 +313,17 @@ func (s Settings) apply(f Form, passwordFile string) (string, error) {
 		system["hostName"] = f.HostName
 	}
 
+	// A VLAN device (enp2s0.1001) is the physical interface plus the
+	// PPPoE session's VLAN.
+	wanDev, wanVLAN := splitVLAN(f.WAN.Interface)
 	if !ifaceRe.MatchString(f.WAN.Interface) {
 		errs["wan.interface"] = "an interface name is required"
 	}
-	wan["interface"] = f.WAN.Interface
+	wan["interface"] = wanDev
 	ipv4cfg := obj(wan, "ipv4")
+	if wanVLAN != 0 && f.WAN.Type != "pppoe" {
+		errs["wan.interface"] = "an uplink on a VLAN needs PPPoE"
+	}
 	switch f.WAN.Type {
 	case "dhcp":
 		ipv4cfg["type"] = "dhcp"
@@ -265,10 +334,8 @@ func (s Settings) apply(f Form, passwordFile string) (string, error) {
 		if pppoe["username"] == "" {
 			errs["wan.pppoe.username"] = "required for PPPoE"
 		}
-		if vlan, ok, err := optionalInt(f.WAN.PPPoEVLAN, 1, 4094); err != nil {
-			errs["wan.pppoe.vlan"] = err.Error()
-		} else if ok {
-			pppoe["vlan"] = vlan
+		if wanVLAN != 0 {
+			pppoe["vlan"] = wanVLAN
 		} else {
 			delete(pppoe, "vlan")
 		}
@@ -280,6 +347,18 @@ func (s Settings) apply(f Form, passwordFile string) (string, error) {
 	default:
 		errs["wan.type"] = "must be dhcp or pppoe"
 	}
+	if f.WAN.IPv6 {
+		v6 := obj(wan, "ipv6")
+		v6["enable"] = true
+		// PPPoE carries IPv6 inside the session; otherwise it is native.
+		if f.WAN.Type == "pppoe" {
+			v6["transport"] = "ppp"
+		} else {
+			v6["transport"] = "native"
+		}
+	} else if v6, ok := wan["ipv6"].(map[string]any); ok {
+		v6["enable"] = false
+	}
 
 	lans := obj(router, "lans")
 	keep := map[string]bool{}
@@ -314,6 +393,14 @@ func (s Settings) apply(f Form, passwordFile string) (string, error) {
 			delete(l, "vlan")
 		}
 		l["internet"] = lf.Internet
+		if lf.IPv6PD {
+			obj(l, "ipv6")["pd"] = true
+		} else if v6, ok := l["ipv6"].(map[string]any); ok {
+			delete(v6, "pd")
+			if len(v6) == 0 {
+				delete(l, "ipv6")
+			}
+		}
 		v4 := obj(l, "ipv4")
 		if _, ok := ipv4(lf.Address); !ok {
 			errs[field("address")] = "an IPv4 address is required"