feat: enforce username length validation in registration and login pr…

cmd/client/chat.go

@@ -561,13 +561,16 @@ func (m *chatModel) refreshChannels(showMessage bool) {
 		return
 	}
 	needsRefresh := false
+	allEncrypted := true
 	for _, ch := range channels {
 		if _, err := m.ensureChannelKey(ch.ID); err != nil {
 			needsRefresh = true
 		}
 		name := m.decryptChannelName(ch.ID, ch.NameEnc)
 		if name == "<encrypted>" {
 			needsRefresh = true
+		} else {
+			allEncrypted = false
 		}
 		m.channels[ch.ID] = channelInfo{ID: ch.ID, Name: name}
 	}
@@ -583,6 +586,9 @@ func (m *chatModel) refreshChannels(showMessage bool) {
 			b.WriteString(")")
 		}
 		m.appendSystemMessage(b.String())
+		if allEncrypted {
+			m.appendSystemMessage("All channels are <encrypted> because no other online user has shared channel keys yet. They will decrypt once another user comes online and shares keys (or an admin re-shares them).")
+		}
 	}
 	m.ensureSidebarIndex()
 	m.channelRefreshNeeded = needsRefresh
@@ -1207,6 +1213,8 @@ func (m *chatModel) renderMessages() string {
 		}
 		if msg.isSystem {
 			sender = "system"
+		} else {
+			sender = formatUsername(sender)
 		}
 
 		var style lipgloss.Style
@@ -1252,7 +1260,7 @@ func (m *chatModel) renderSidebar() string {
 							style = sidebarOfflineStyle
 						}
 					}
-					name := entry.Name
+					name := formatUsername(entry.Name)
 					if entry.Admin {
 						name = fmt.Sprintf("%s (admin)", name)
 					}
@@ -1278,7 +1286,7 @@ func (m *chatModel) renderSidebar() string {
 							style = sidebarOfflineStyle
 						}
 					}
-					name := entry.Name
+					name := formatUsername(entry.Name)
 					if entry.Admin {
 						name = fmt.Sprintf("%s (admin)", name)
 					}
@@ -1637,7 +1645,7 @@ func (m chatModel) View() string {
 	header := fmt.Sprintf(
 		"  %s  %s  %s  %s",
 		appNameStyle.Render("* dialtone"),
-		headerStyle.Render(m.auth.Username),
+		headerStyle.Render(formatUsername(m.auth.Username)),
 		labelStyle.Render(shortID(m.auth.UserID)),
 		labelStyle.Render(m.activeChannelLabel()),
 	)
@@ -1702,6 +1710,17 @@ func shortID(id string) string {
 	return id
 }
 
+func formatUsername(name string) string {
+	name = strings.TrimSpace(name)
+	if name == "" {
+		return name
+	}
+	if strings.HasPrefix(name, "<") && strings.HasSuffix(name, ">") {
+		return name
+	}
+	return "<" + name + ">"
+}
+
 func clampMin(v, minimum int) int {
 	if v < minimum {
 		return minimum

cmd/client/login.go

@@ -27,6 +27,11 @@ type loginModel struct {
 	selectIndex   int
 }
 
+const (
+	minUsernameLen = 2
+	maxUsernameLen = 20
+)
+
 func newLoginModel(defaultServer string) loginModel {
 	server := textinput.New()
 	server.Placeholder = "http://localhost:8080"
@@ -41,8 +46,8 @@ func newLoginModel(defaultServer string) loginModel {
 	server.Focus()
 
 	username := textinput.New()
-	username.Placeholder = "username"
-	username.CharLimit = 64
+	username.Placeholder = "username (2-20 chars)"
+	username.CharLimit = maxUsernameLen
 	username.Width = 30
 
 	password := textinput.New()
@@ -307,9 +312,13 @@ func (m loginModel) validateSubmit() string {
 	if strings.TrimSpace(m.serverURL()) == "" {
 		return "server url is required"
 	}
-	if m.username() == "" || m.password() == "" {
+	username := strings.TrimSpace(m.username())
+	if username == "" || m.password() == "" {
 		return "username and password are required"
 	}
+	if len(username) < minUsernameLen || len(username) > maxUsernameLen {
+		return fmt.Sprintf("username must be %d-%d characters", minUsernameLen, maxUsernameLen)
+	}
 	if len(m.passphrase()) < 8 {
 		return "keystore passphrase must be at least 8 characters"
 	}

cmd/client/login_test.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"strings"
 	"testing"
 
 	tea "github.com/charmbracelet/bubbletea"
@@ -15,6 +16,19 @@ func TestLoginValidateSubmit(t *testing.T) {
 		t.Fatalf("unexpected error: %s", msg)
 	}
 
+	m.usernameInput.SetValue("a")
+	if msg := m.validateSubmit(); msg == "" {
+		t.Fatalf("expected username length error")
+	}
+
+	m.usernameInput.CharLimit = 0
+	m.usernameInput.SetValue(strings.Repeat("a", 21))
+	if msg := m.validateSubmit(); msg == "" {
+		t.Fatalf("expected username max length error")
+	}
+
+	m.usernameInput.SetValue("alice")
+
 	m.passphraseInp.SetValue("short")
 	if msg := m.validateSubmit(); msg == "" {
 		t.Fatalf("expected passphrase error")

internal/auth/auth.go

@@ -23,6 +23,11 @@ var (
 	ErrTokenExpired = errors.New("token expired")
 )
 
+const (
+	minUsernameLen = 2
+	maxUsernameLen = 20
+)
+
 type Session struct {
 	Token     string
 	UserID    user.ID
@@ -59,8 +64,8 @@ func (s *Service) Register(ctx context.Context, username, password, publicKey, i
 		return user.User{}, device.Device{}, Session{}, errors.New("invites service is required")
 	}
 	name := normalizeUsername(username)
-	if name == "" {
-		return user.User{}, device.Device{}, Session{}, ErrInvalidInput
+	if err := validateUsername(name); err != nil {
+		return user.User{}, device.Device{}, Session{}, err
 	}
 	if err := validateRegisterPassword(password); err != nil {
 		return user.User{}, device.Device{}, Session{}, err
@@ -107,8 +112,8 @@ func (s *Service) Login(ctx context.Context, username, password, publicKey strin
 		return user.User{}, device.Device{}, Session{}, errors.New("services are required")
 	}
 	name := normalizeUsername(username)
-	if name == "" {
-		return user.User{}, device.Device{}, Session{}, ErrInvalidInput
+	if err := validateUsername(name); err != nil {
+		return user.User{}, device.Device{}, Session{}, err
 	}
 	if strings.TrimSpace(password) == "" || len(password) < 8 {
 		return user.User{}, device.Device{}, Session{}, ErrInvalidInput
@@ -219,6 +224,16 @@ func normalizeUsername(username string) string {
 	return strings.ToLower(strings.TrimSpace(username))
 }
 
+func validateUsername(name string) error {
+	if name == "" {
+		return ErrInvalidInput
+	}
+	if len(name) < minUsernameLen || len(name) > maxUsernameLen {
+		return fmt.Errorf("%w: username must be %d-%d characters", ErrInvalidInput, minUsernameLen, maxUsernameLen)
+	}
+	return nil
+}
+
 type tokenStore struct {
 	mu       sync.Mutex
 	sessions map[string]Session

internal/auth/auth_test.go

@@ -224,6 +224,23 @@ func TestRegister_EmptyUsername(t *testing.T) {
 	}
 }
 
+func TestRegister_ShortUsername(t *testing.T) {
+	svc := newTestService()
+	_, _, _, err := svc.Register(context.Background(), "a", "password123", "a2V5", "invite-1")
+	if !errors.Is(err, ErrInvalidInput) {
+		t.Fatalf("expected ErrInvalidInput, got %v", err)
+	}
+}
+
+func TestRegister_LongUsername(t *testing.T) {
+	svc := newTestService()
+	longName := strings.Repeat("a", 21)
+	_, _, _, err := svc.Register(context.Background(), longName, "password123", "a2V5", "invite-1")
+	if !errors.Is(err, ErrInvalidInput) {
+		t.Fatalf("expected ErrInvalidInput, got %v", err)
+	}
+}
+
 func TestLogin_Success(t *testing.T) {
 	svc := newTestService()
 	ctx := context.Background()

internal/user/service.go

@@ -14,6 +14,11 @@ import (
 
 var ErrInvalidInput = errors.New("invalid input")
 
+const (
+	minUsernameLen = 2
+	maxUsernameLen = 20
+)
+
 type Service struct {
 	repo   Repository
 	idGen  func() ID
@@ -38,8 +43,8 @@ func (s *Service) Create(ctx context.Context, username string) (User, error) {
 	}
 
 	name := normalizeUsername(username)
-	if name == "" {
-		return User{}, ErrInvalidInput
+	if err := validateUsername(name); err != nil {
+		return User{}, err
 	}
 	if len(s.pepper) == 0 {
 		return User{}, errors.New("username pepper is required")
@@ -67,7 +72,10 @@ func (s *Service) CreateWithPassword(ctx context.Context, username, passwordHash
 	}
 
 	name := normalizeUsername(username)
-	if name == "" || strings.TrimSpace(passwordHash) == "" {
+	if err := validateUsername(name); err != nil {
+		return User{}, err
+	}
+	if strings.TrimSpace(passwordHash) == "" {
 		return User{}, ErrInvalidInput
 	}
 	if len(s.pepper) == 0 {
@@ -98,7 +106,10 @@ func (s *Service) CreateWithPasswordAndID(ctx context.Context, id ID, username,
 		return User{}, ErrInvalidInput
 	}
 	name := normalizeUsername(username)
-	if name == "" || strings.TrimSpace(passwordHash) == "" {
+	if err := validateUsername(name); err != nil {
+		return User{}, err
+	}
+	if strings.TrimSpace(passwordHash) == "" {
 		return User{}, ErrInvalidInput
 	}
 	if len(s.pepper) == 0 {
@@ -147,8 +158,8 @@ func (s *Service) GetByUsername(ctx context.Context, username string) (User, err
 		return User{}, errors.New("repository is required")
 	}
 	name := normalizeUsername(username)
-	if name == "" {
-		return User{}, ErrInvalidInput
+	if err := validateUsername(name); err != nil {
+		return User{}, err
 	}
 	if len(s.pepper) == 0 {
 		return User{}, errors.New("username pepper is required")
@@ -208,6 +219,16 @@ func normalizeUsername(username string) string {
 	return strings.ToLower(strings.TrimSpace(username))
 }
 
+func validateUsername(name string) error {
+	if name == "" {
+		return ErrInvalidInput
+	}
+	if len(name) < minUsernameLen || len(name) > maxUsernameLen {
+		return ErrInvalidInput
+	}
+	return nil
+}
+
 func hashUsername(pepper []byte, username string) string {
 	mac := hmac.New(sha256.New, pepper)
 	_, _ = mac.Write([]byte(username))

internal/user/service_test.go

@@ -3,6 +3,7 @@ package user
 import (
 	"context"
 	"errors"
+	"strings"
 	"testing"
 	"time"
 )
@@ -119,6 +120,25 @@ func TestCreate_WhitespaceUsername(t *testing.T) {
 	}
 }
 
+func TestCreate_ShortUsername(t *testing.T) {
+	svc, _ := newTestService()
+
+	_, err := svc.Create(context.Background(), "a")
+	if !errors.Is(err, ErrInvalidInput) {
+		t.Fatalf("expected ErrInvalidInput, got %v", err)
+	}
+}
+
+func TestCreate_LongUsername(t *testing.T) {
+	svc, _ := newTestService()
+	longName := strings.Repeat("a", 21)
+
+	_, err := svc.Create(context.Background(), longName)
+	if !errors.Is(err, ErrInvalidInput) {
+		t.Fatalf("expected ErrInvalidInput, got %v", err)
+	}
+}
+
 func TestCreate_TrimsWhitespace(t *testing.T) {
 	svc, _ := newTestService()