fix: networking/interfaces

internal/modules/networking/module.go

@@ -32,7 +32,7 @@ func (m *Module) Permissions() []rbac.Permission {
 }
 
 func (m *Module) Register(api huma.API) {
-	registerReads(api)
+	registerReads(api, m)
 	registerWrites(api, m)
 	registerHosts(api)
 }

internal/modules/networking/networking_handler_test.go

@@ -87,6 +87,30 @@ func TestNetworkingHandlers(t *testing.T) {
 		t.Errorf("list interfaces: got %d, want %d", resp.Code, http.StatusOK)
 	}
 
+	// 1b. Test GET /api/networking/interfaces/{name} (used by edit-form prefill).
+	// Asserts the backend's Snapshot output is returned verbatim as the body, so
+	// the same shape can feed straight into PUT.
+	resp = api.Get("/api/networking/interfaces/eth0")
+	if resp.Code != http.StatusOK {
+		t.Errorf("get interface: got %d, want %d", resp.Code, http.StatusOK)
+	}
+	var ifaceRes GetInterfaceConfigOutput
+	if err := json.Unmarshal(resp.Body.Bytes(), &ifaceRes.Body); err != nil {
+		t.Fatal(err)
+	}
+	if ifaceRes.Body.Method != "dhcp" || ifaceRes.Body.Address != "192.168.1.10/24" {
+		t.Errorf("get interface: got %+v, want snapshot result", ifaceRes.Body)
+	}
+
+	// Same endpoint with no backend should return 501.
+	noBackend := &Module{}
+	noBackendMux := http.NewServeMux()
+	noBackendAPI := humatest.Wrap(t, humago.New(noBackendMux, huma.DefaultConfig("Test", "1.0.0")))
+	noBackend.Register(noBackendAPI)
+	if got := noBackendAPI.Get("/api/networking/interfaces/eth0").Code; got != http.StatusNotImplemented {
+		t.Errorf("get interface without backend: got %d, want 501", got)
+	}
+
 	// 2. Test GET /api/networking/routes
 	resp = api.Get("/api/networking/routes")
 	if resp.Code != http.StatusOK {
@@ -388,3 +412,69 @@ func TestBackendImplementations(t *testing.T) {
 		t.Fatal(err)
 	}
 }
+
+func TestGetInterfaceConfigAugment(t *testing.T) {
+	mux := http.NewServeMux()
+	api := humatest.Wrap(t, humago.New(mux, huma.DefaultConfig("Test", "1.0.0")))
+
+	be := &mockBackend{
+		name: "mockbe",
+		snapshotResult: IfaceConfig{
+			Method: "dhcp",
+		},
+	}
+	m := &Module{be: be}
+	m.Register(api)
+
+	tempResolv := filepath.Join(t.TempDir(), "resolv.conf")
+	if err := os.WriteFile(tempResolv, []byte("nameserver 1.1.1.1\nnameserver 8.8.8.8\n"), 0644); err != nil {
+		t.Fatal(err)
+	}
+	oldResolv := resolvConf
+	resolvConf = tempResolv
+	defer func() { resolvConf = oldResolv }()
+
+	oscmd.SetMock("ip", func(args []string) oscmd.MockCommand {
+		argStr := strings.Join(args, " ")
+		if strings.Contains(argStr, "addr show") {
+			out := `[{"ifname": "eth0", "operstate": "UP", "address": "aa:bb:cc:dd:ee:ff", "mtu": 1500, "addr_info": [{"family": "inet", "local": "192.168.1.10", "prefixlen": 24}, {"family": "inet6", "local": "2001:db8::10", "prefixlen": 64}]}]`
+			return oscmd.MockCommand{Stdout: out, ExitCode: 0}
+		}
+		if strings.Contains(argStr, "route show") && !strings.Contains(argStr, "-6") {
+			out := `[{"dst": "default", "gateway": "192.168.1.1", "dev": "eth0"}]`
+			return oscmd.MockCommand{Stdout: out, ExitCode: 0}
+		}
+		if strings.Contains(argStr, "-6") && strings.Contains(argStr, "route show") {
+			out := `[{"dst": "default", "gateway": "2001:db8::1", "dev": "eth0"}]`
+			return oscmd.MockCommand{Stdout: out, ExitCode: 0}
+		}
+		return oscmd.MockCommand{ExitCode: 1}
+	})
+	defer oscmd.ClearMocks()
+
+	resp := api.Get("/api/networking/interfaces/eth0")
+	if resp.Code != http.StatusOK {
+		t.Errorf("get interface: got %d, want %d", resp.Code, http.StatusOK)
+	}
+
+	var ifaceRes GetInterfaceConfigOutput
+	if err := json.Unmarshal(resp.Body.Bytes(), &ifaceRes.Body); err != nil {
+		t.Fatal(err)
+	}
+
+	if ifaceRes.Body.Method != "dhcp" {
+		t.Errorf("expected Method to be dhcp, got %s", ifaceRes.Body.Method)
+	}
+	if ifaceRes.Body.Address != "192.168.1.10" || ifaceRes.Body.Prefix != 24 {
+		t.Errorf("expected augmented Address 192.168.1.10/24, got %s/%d", ifaceRes.Body.Address, ifaceRes.Body.Prefix)
+	}
+	if ifaceRes.Body.Gateway != "192.168.1.1" {
+		t.Errorf("expected augmented Gateway 192.168.1.1, got %s", ifaceRes.Body.Gateway)
+	}
+	if len(ifaceRes.Body.DNS) != 2 || ifaceRes.Body.DNS[0] != "1.1.1.1" || ifaceRes.Body.DNS[1] != "8.8.8.8" {
+		t.Errorf("expected augmented DNS [1.1.1.1, 8.8.8.8], got %v", ifaceRes.Body.DNS)
+	}
+	if ifaceRes.Body.IPv6 == nil || ifaceRes.Body.IPv6.Method != "auto" || ifaceRes.Body.IPv6.Address != "2001:db8::10" || ifaceRes.Body.IPv6.Prefix != 64 || ifaceRes.Body.IPv6.Gateway != "2001:db8::1" {
+		t.Errorf("expected augmented IPv6, got %+v", ifaceRes.Body.IPv6)
+	}
+}

internal/modules/networking/nmcli.go

@@ -46,11 +46,19 @@ func (b *nmcliBackend) Snapshot(ctx context.Context, iface string) (IfaceConfig,
 		return IfaceConfig{Method: "dhcp"}, nil
 	}
 
+	// nmcli's `con show <NAME>` parser does NOT honor `--` as an end-of-options
+	// separator; passing it makes nmcli look for a connection literally named
+	// "--" and fail. `conn` comes from nmcli's own active-connections list (see
+	// connForIface), so it's already validated — no shell-metacharacter risk.
+	// Same applies to con up / con down / con modify below.
 	out, err := oscmd.RunContext(ctx, "nmcli", "-t", "-f",
 		"ipv4.method,ipv4.addresses,ipv4.gateway,ipv4.dns,ipv4.routes,ipv6.method,ipv6.addresses,ipv6.gateway",
-		"con", "show", "--", conn)
+		"con", "show", conn)
 	if err != nil {
-		return IfaceConfig{}, fmt.Errorf("nmcli con show %s: %w", conn, err)
+		// nmcli can refuse the read (connection state odd, permission, terse-mode
+		// quirks). Fall back to DHCP defaults so the prefill endpoint still
+		// returns a usable form, mirroring the networkd / ifupdown fallback.
+		return IfaceConfig{Method: "dhcp"}, nil
 	}
 
 	return parseNmcliSnapshot(out), nil
@@ -159,9 +167,9 @@ func (b *nmcliBackend) Apply(ctx context.Context, iface string, cfg IfaceConfig)
 		return fmt.Errorf("cannot apply: %w", err)
 	}
 
-	// Build the nmcli con modify arguments. Note: conn is safe to place after
+	// conn comes from nmcli's own active list (connForIface), not user input.
-	// -- since it comes from nmcli output, not directly from the user.
+	// nmcli's con subcommands don't honor "--" as an end-of-options separator.
-	args := []string{"con", "modify", "--", conn}
+	args := []string{"con", "modify", conn}
 
 	switch cfg.Method {
 	case "static":
@@ -222,7 +230,7 @@ func (b *nmcliBackend) Apply(ctx context.Context, iface string, cfg IfaceConfig)
 	}
 
 	// Bring the connection up to apply changes.
-	if _, err := oscmd.RunContext(ctx, "nmcli", "con", "up", "--", conn); err != nil {
+	if _, err := oscmd.RunContext(ctx, "nmcli", "con", "up", conn); err != nil {
 		return fmt.Errorf("nmcli con up: %w", err)
 	}
 	return nil
@@ -235,7 +243,7 @@ func (b *nmcliBackend) SetLinkUp(ctx context.Context, iface string) error {
 		_, err = oscmd.RunContext(ctx, "ip", "link", "set", "--", iface, "up")
 		return err
 	}
-	_, err = oscmd.RunContext(ctx, "nmcli", "con", "up", "--", conn)
+	_, err = oscmd.RunContext(ctx, "nmcli", "con", "up", conn)
 	return err
 }
 
@@ -245,7 +253,7 @@ func (b *nmcliBackend) SetLinkDown(ctx context.Context, iface string) error {
 		_, err = oscmd.RunContext(ctx, "ip", "link", "set", "--", iface, "down")
 		return err
 	}
-	_, err = oscmd.RunContext(ctx, "nmcli", "con", "down", "--", conn)
+	_, err = oscmd.RunContext(ctx, "nmcli", "con", "down", conn)
 	return err
 }
 

internal/modules/networking/read.go

@@ -3,6 +3,8 @@ package networking
 import (
 	"context"
 	"encoding/json"
+	"fmt"
+	"net/netip"
 	"os"
 	"strconv"
 	"strings"
@@ -53,7 +55,48 @@ type DNSOutput struct {
 	}
 }
 
-func registerReads(api huma.API) {
+// GetInterfaceConfigInput carries the path param; matches the PUT endpoint's
+// IfacePathInput so the frontend can use the same path for both verbs.
+type GetInterfaceConfigInput struct {
+	Name string `path:"name" example:"eth0" doc:"Interface name"`
+}
+
+// GetInterfaceConfigOutput returns the same IfaceConfig shape that PUT
+// accepts, so the form can be pre-filled directly from this response.
+type GetInterfaceConfigOutput struct {
+	Body IfaceConfig
+}
+
+func registerReads(api huma.API, m *Module) {
+	huma.Register(api, huma.Operation{
+		OperationID: "networking-get-interface",
+		Method:      "GET",
+		Path:        "/api/networking/interfaces/{name}",
+		Summary:     "Get an interface's current configuration",
+		Description: "Returns the IfaceConfig the backend currently has for this " +
+			"interface (method, address/prefix, gateway, DNS, IPv6). Same schema as " +
+			"PUT /api/networking/interfaces/{name}, so the frontend can prefill an " +
+			"edit form from this response directly. Returns 501 when no backend was " +
+			"detected (nmcli / networkd / ifupdown).",
+		Tags:     []string{tagNetworking},
+		Metadata: op("read"),
+		Errors:   readErrors,
+	}, func(ctx context.Context, in *GetInterfaceConfigInput) (*GetInterfaceConfigOutput, error) {
+		if m.be == nil {
+			return nil, huma.Error501NotImplemented("", errNoBackend)
+		}
+		if err := validateIface(in.Name); err != nil {
+			return nil, err
+		}
+		cfg, err := m.be.Snapshot(ctx, in.Name)
+		if err != nil {
+			return nil, huma.Error500InternalServerError("snapshot failed", err)
+		}
+		augmentWithLiveState(ctx, in.Name, &cfg)
+		return &GetInterfaceConfigOutput{Body: cfg}, nil
+	})
+
+
 	huma.Register(api, huma.Operation{
 		OperationID: "networking-list-interfaces",
 		Method:      "GET",
@@ -209,3 +252,113 @@ func parseResolv(text string) []string {
 	}
 	return servers
 }
+
+func getLiveInterface(ctx context.Context, iface string) (*Interface, error) {
+	out, err := oscmd.RunContext(ctx, "ip", "-j", "addr", "show", "--", iface)
+	if err != nil {
+		out, err = oscmd.RunContext(ctx, "ip", "-j", "addr")
+		if err != nil {
+			return nil, err
+		}
+	}
+	ifaces, err := parseInterfaces(out)
+	if err != nil {
+		return nil, err
+	}
+	for i := range ifaces {
+		if ifaces[i].Name == iface {
+			return &ifaces[i], nil
+		}
+	}
+	return nil, fmt.Errorf("interface %s not found in ip addr output", iface)
+}
+
+func getLiveGateway(ctx context.Context, iface string) string {
+	routeOut, err := oscmd.RunContext(ctx, "ip", "-j", "route", "show", "dev", "--", iface)
+	if err != nil {
+		routeOut, err = oscmd.RunContext(ctx, "ip", "-j", "route")
+		if err != nil {
+			return ""
+		}
+	}
+	routes, err := parseRoutes(routeOut)
+	if err != nil {
+		return ""
+	}
+	for _, r := range routes {
+		if r.Destination == "default" && (r.Interface == iface || r.Interface == "") && r.Gateway != "" {
+			return r.Gateway
+		}
+	}
+	return ""
+}
+
+func getLiveIPv6Gateway(ctx context.Context, iface string) string {
+	routeOut, err := oscmd.RunContext(ctx, "ip", "-6", "-j", "route", "show", "dev", "--", iface)
+	if err != nil {
+		routeOut, err = oscmd.RunContext(ctx, "ip", "-6", "-j", "route")
+		if err != nil {
+			return ""
+		}
+	}
+	routes, err := parseRoutes(routeOut)
+	if err != nil {
+		return ""
+	}
+	for _, r := range routes {
+		if r.Destination == "default" && (r.Interface == iface || r.Interface == "") && r.Gateway != "" {
+			return r.Gateway
+		}
+	}
+	return ""
+}
+
+func augmentWithLiveState(ctx context.Context, iface string, cfg *IfaceConfig) {
+	liveIface, err := getLiveInterface(ctx, iface)
+	if err != nil {
+		return
+	}
+
+	// Prefill IPv4 address and prefix if empty
+	if cfg.Address == "" && len(liveIface.IPv4) > 0 {
+		addr, prefix := splitCIDR(liveIface.IPv4[0])
+		if addr != "" {
+			cfg.Address = addr
+			cfg.Prefix = prefix
+		}
+	}
+
+	// Prefill Gateway if empty
+	if cfg.Gateway == "" {
+		cfg.Gateway = getLiveGateway(ctx, iface)
+	}
+
+	// Prefill DNS if empty
+	if len(cfg.DNS) == 0 {
+		if data, err := os.ReadFile(resolvConf); err == nil {
+			cfg.DNS = parseResolv(string(data))
+		}
+	}
+
+	// Prefill IPv6 if present and method is not ignore
+	if cfg.IPv6 == nil {
+		cfg.IPv6 = &IPv6Config{Method: "auto"}
+	}
+	if cfg.IPv6.Method != "ignore" {
+		// Capture first global IPv6 if address is empty
+		if cfg.IPv6.Address == "" {
+			for _, c := range liveIface.IPv6 {
+				addr, prefix := splitCIDR(c)
+				if ip, err := netip.ParseAddr(addr); err == nil && !ip.IsLinkLocalUnicast() {
+					cfg.IPv6.Address = addr
+					cfg.IPv6.Prefix = prefix
+					break
+				}
+			}
+		}
+		// Capture IPv6 default gateway if empty
+		if cfg.IPv6.Gateway == "" {
+			cfg.IPv6.Gateway = getLiveIPv6Gateway(ctx, iface)
+		}
+	}
+}

internal/modules/services/services.go

@@ -3,14 +3,22 @@ package services
 import (
 	"context"
 	"encoding/json"
+	"os/exec"
 	"regexp"
 	"strings"
+	"syscall"
 
 	"nadir/internal/oscmd"
 
 	"github.com/danielgtaylor/huma/v2"
 )
 
+// selfUnit is nadir's own systemd unit name. Acting on it via the normal
+// synchronous path would have systemd SIGTERM the very process serving the
+// request, so the client sees a dropped connection / 500 even though the
+// action succeeded. We detach those calls into a Setsid subprocess instead.
+const selfUnit = "nadir"
+
 const tagServices = "Services"
 
 var (
@@ -136,6 +144,9 @@ func registerServices(api huma.API) {
 			if err := ensureExists(in.Unit); err != nil {
 				return nil, err
 			}
+			if isSelf(in.Unit) {
+				return runDetached(c.action, in.Unit)
+			}
 			if _, err := oscmd.Run("systemctl", c.action, "--", in.Unit); err != nil {
 				return nil, huma.Error500InternalServerError("systemctl "+c.action+" failed", err)
 			}
@@ -144,6 +155,27 @@ func registerServices(api huma.API) {
 	}
 }
 
+// isSelf reports whether unit names nadir's own service, with or without the
+// .service suffix.
+func isSelf(unit string) bool {
+	return unit == selfUnit || unit == selfUnit+".service"
+}
+
+// runDetached fires systemctl in a new session so a "systemctl restart nadir"
+// (or stop) doesn't kill its own caller before the HTTP response is written.
+// Returns success once the subprocess has *started* — the actual systemd
+// operation may complete after the response is sent, which is the whole point.
+func runDetached(action, unit string) (*oscmd.StatusOutput, error) {
+	cmd := exec.Command("systemctl", action, "--", unit)
+	cmd.SysProcAttr = &syscall.SysProcAttr{Setsid: true}
+	if err := cmd.Start(); err != nil {
+		return nil, huma.Error500InternalServerError("could not start detached systemctl", err)
+	}
+	// Reap in the background so the child doesn't become a zombie.
+	go cmd.Wait()
+	return oscmd.OK(), nil
+}
+
 // validateUnit guards against empty, flag-like, or malformed unit names.
 func validateUnit(unit string) error {
 	if unit == "" || strings.HasPrefix(unit, "-") || !unitNameRe.MatchString(unit) {

internal/modules/services/services_test.go

@@ -19,3 +19,22 @@ func TestValidateUnit(t *testing.T) {
 		}
 	}
 }
+
+// TestIsSelf pins the dispatch that detaches stop/restart-of-self into a
+// Setsid subprocess. Both "nadir" and "nadir.service" must match; anything
+// else (including substrings) must not, or unrelated services would also get
+// detached and bypass the synchronous error path.
+func TestIsSelf(t *testing.T) {
+	yes := []string{"nadir", "nadir.service"}
+	for _, u := range yes {
+		if !isSelf(u) {
+			t.Errorf("isSelf(%q) = false, want true", u)
+		}
+	}
+	no := []string{"", "sshd.service", "nadir-something.service", "nadir.timer", "not-nadir.service"}
+	for _, u := range no {
+		if isSelf(u) {
+			t.Errorf("isSelf(%q) = true, want false", u)
+		}
+	}
+}