Merge support for the UNSELECT extension

Author: foxcpp

README.md

@@ -133,6 +133,7 @@ includes:
 * [SASL-IR](https://tools.ietf.org/html/rfc4959)
 * [SPECIAL-USE](https://tools.ietf.org/html/rfc6154)
 * [CHILDREN](https://tools.ietf.org/html/rfc3348)
+* [UNSELECT](https://tools.ietf.org/html/rfc3691)
 
 Support for other extensions is provided via separate packages. See below.
 
@@ -154,7 +155,6 @@ to learn how to use them.
 * [NAMESPACE](https://github.com/foxcpp/go-imap-namespace)
 * [QUOTA](https://github.com/emersion/go-imap-quota)
 * [SORT and THREAD](https://github.com/emersion/go-imap-sortthread)
-* [UNSELECT](https://github.com/emersion/go-imap-unselect)
 * [UIDPLUS](https://github.com/emersion/go-imap-uidplus)
 
 ### Server backends

client/client_test.go

@@ -49,7 +49,7 @@ func (c *serverConn) WriteString(s string) (n int, err error) {
 }
 
 func newTestClient(t *testing.T) (c *Client, s *serverConn) {
-	return newTestClientWithGreeting(t, "* OK [CAPABILITY IMAP4rev1 STARTTLS AUTH=PLAIN] Server ready.\r\n")
+	return newTestClientWithGreeting(t, "* OK [CAPABILITY IMAP4rev1 STARTTLS AUTH=PLAIN UNSELECT] Server ready.\r\n")
 }
 
 func newTestClientWithGreeting(t *testing.T, greeting string) (c *Client, s *serverConn) {

client/cmd_any.go

@@ -49,6 +49,7 @@ func (c *Client) Support(cap string) (bool, error) {
 	c.locker.Lock()
 	supported := c.caps[cap]
 	c.locker.Unlock()
+
 	return supported, nil
 }
 

client/cmd_selected.go

@@ -8,9 +8,15 @@ import (
 	"github.com/emersion/go-imap/responses"
 )
 
-// ErrNoMailboxSelected is returned if a command that requires a mailbox to be
-// selected is called when there isn't.
-var ErrNoMailboxSelected = errors.New("No mailbox selected")
+var (
+	// ErrNoMailboxSelected is returned if a command that requires a mailbox to be
+	// selected is called when there isn't.
+	ErrNoMailboxSelected = errors.New("No mailbox selected")
+
+	// ErrExtensionUnsupported is returned if a command uses a extension that
+	// is not supported by the server.
+	ErrExtensionUnsupported = errors.New("The required extension is not supported by the server")
+)
 
 // Check requests a checkpoint of the currently selected mailbox. A checkpoint
 // refers to any implementation-dependent housekeeping associated with the
@@ -265,3 +271,30 @@ func (c *Client) Copy(seqset *imap.SeqSet, dest string) error {
 func (c *Client) UidCopy(seqset *imap.SeqSet, dest string) error {
 	return c.copy(true, seqset, dest)
 }
+
+// Unselect frees server's resources associated with the selected mailbox and
+// returns the server to the authenticated state. This command performs the same
+// actions as Close, except that no messages are permanently removed from the
+// currently selected mailbox.
+//
+// If client does not support the UNSELECT extension, ErrExtensionUnsupported
+// is returned.
+func (c *Client) Unselect() error {
+	if ok, err := c.Support("UNSELECT"); !ok || err != nil {
+		return ErrExtensionUnsupported
+	}
+
+	if c.State() != imap.SelectedState {
+		return ErrNoMailboxSelected
+	}
+
+	cmd := &commands.Unselect{}
+	if status, err := c.Execute(cmd, nil); err != nil {
+		return err
+	} else if err := status.Err(); err != nil {
+		return err
+	}
+
+	c.SetState(imap.AuthenticatedState, nil)
+	return nil
+}

client/cmd_selected_test.go

@@ -632,3 +632,30 @@ func TestClient_Copy_Uid(t *testing.T) {
 		t.Fatalf("c.UidCopy() = %v", err)
 	}
 }
+
+func TestClient_Unselect(t *testing.T) {
+	c, s := newTestClient(t)
+	defer s.Close()
+
+	setClientState(c, imap.SelectedState, nil)
+
+	done := make(chan error, 1)
+	go func() {
+		done <- c.Unselect()
+	}()
+
+	tag, cmd := s.ScanCmd()
+	if cmd != "UNSELECT" {
+		t.Fatalf("client sent command %v, want %v", cmd, "UNSELECT")
+	}
+
+	s.WriteString(tag + " OK UNSELECT completed\r\n")
+
+	if err := <-done; err != nil {
+		t.Fatalf("c.Unselect() = %v", err)
+	}
+
+	if c.State() != imap.AuthenticatedState {
+		t.Fatal("Client is not Authenticated after UNSELECT")
+	}
+}

commands/unselect.go

@@ -0,0 +1,17 @@
+package commands
+
+import (
+	"github.com/emersion/go-imap"
+)
+
+// An UNSELECT command.
+// See RFC 3691 section 2.
+type Unselect struct{}
+
+func (cmd *Unselect) Command() *imap.Command {
+	return &imap.Command{Name: "UNSELECT"}
+}
+
+func (cmd *Unselect) Parse(fields []interface{}) error {
+	return nil
+}

server/cmd_auth.go

@@ -275,3 +275,18 @@ func (cmd *Append) Handle(conn Conn) error {
 
 	return nil
 }
+
+type Unselect struct {
+	commands.Unselect
+}
+
+func (cmd *Unselect) Handle(conn Conn) error {
+	ctx := conn.Context()
+	if ctx.Mailbox == nil {
+		return ErrNoMailboxSelected
+	}
+
+	ctx.Mailbox = nil
+	ctx.MailboxReadOnly = false
+	return nil
+}

server/conn.go

@@ -163,7 +163,7 @@ func (c *conn) Close() error {
 }
 
 func (c *conn) Capabilities() []string {
-	caps := []string{"IMAP4rev1", "LITERAL+", "SASL-IR", "CHILDREN"}
+	caps := []string{"IMAP4rev1", "LITERAL+", "SASL-IR", "CHILDREN", "UNSELECT"}
 
 	if c.ctx.State == imap.NotAuthenticatedState {
 		if !c.IsTLS() && c.s.TLSConfig != nil {

server/server.go

@@ -185,6 +185,8 @@ func New(bkd backend.Backend) *Server {
 		"STORE":   func() Handler { return &Store{} },
 		"COPY":    func() Handler { return &Copy{} },
 		"UID":     func() Handler { return &Uid{} },
+
+		"UNSELECT": func() Handler { return &Unselect{} },
 	}
 
 	return s
@@ -400,7 +402,13 @@ func (s *Server) Close() error {
 // Enable some IMAP extensions on this server.
 // Wiki entry: https://github.com/emersion/go-imap/wiki/Using-extensions
 func (s *Server) Enable(extensions ...Extension) {
-	s.extensions = append(s.extensions, extensions...)
+	for _, ext := range extensions {
+		// Ignore built-in extensions
+		if ext.Command("UNSELECT") != nil {
+			continue
+		}
+		s.extensions = append(s.extensions, ext)
+	}
 }
 
 // Enable an authentication mechanism on this server.

server/server_test.go

@@ -10,7 +10,7 @@ import (
 )
 
 // Extnesions that are always advertised by go-imap server.
-const builtinExtensions = "LITERAL+ SASL-IR CHILDREN"
+const builtinExtensions = "LITERAL+ SASL-IR CHILDREN UNSELECT"
 
 func testServer(t *testing.T) (s *server.Server, conn net.Conn) {
 	bkd := memory.New()