imapserver: add SupportedCaps

Author: emersion

imapserver/capability.go

@@ -29,15 +29,15 @@ func (c *Conn) availableCaps() []imap.Cap {
 	available := c.server.options.caps()
 
 	var caps []imap.Cap
-	addAvailableCaps(&caps, available, []imap.Cap{
-		imap.CapIMAP4rev2,
-		imap.CapIMAP4rev1,
+	addAvailableCaps(&caps, map[imap.Cap]bool{
+		imap.CapIMAP4rev2: available.IMAP4rev1,
+		imap.CapIMAP4rev1: available.IMAP4rev2,
 	})
 	if len(caps) == 0 {
 		panic("imapserver: must support at least IMAP4rev1 or IMAP4rev2")
 	}
 
-	if available.Has(imap.CapIMAP4rev1) {
+	if available.IMAP4rev1 {
 		caps = append(caps, []imap.Cap{
 			imap.CapSASLIR,
 			imap.CapLiteralMinus,
@@ -58,7 +58,7 @@ func (c *Conn) availableCaps() []imap.Cap {
 		caps = append(caps, imap.CapLoginDisabled)
 	}
 	if c.state == imap.ConnStateAuthenticated || c.state == imap.ConnStateSelected {
-		if available.Has(imap.CapIMAP4rev1) {
+		if available.IMAP4rev1 {
 			// IMAP4rev1-specific capabilities that don't require backend
 			// support and are not applicable to IMAP4rev2
 			caps = append(caps, []imap.Cap{
@@ -70,35 +70,35 @@ func (c *Conn) availableCaps() []imap.Cap {
 
 			// IMAP4rev1-specific capabilities which require backend support
 			// and are not applicable to IMAP4rev2
-			addAvailableCaps(&caps, available, []imap.Cap{
-				imap.CapNamespace,
-				imap.CapUIDPlus,
-				imap.CapESearch,
-				imap.CapSearchRes,
-				imap.CapListExtended,
-				imap.CapListStatus,
-				imap.CapMove,
-				imap.CapStatusSize,
-				imap.CapBinary,
-				imap.CapChildren,
+			addAvailableCaps(&caps, map[imap.Cap]bool{
+				imap.CapNamespace: available.Namespace,
+				imap.CapUIDPlus:   available.UIDPlus,
+				imap.CapESearch:   available.ESearch,
+				//imap.CapSearchRes: available.SearchRes,
+				imap.CapListExtended: available.ListExtended,
+				imap.CapListStatus:   available.ListStatus,
+				imap.CapMove:         available.Move,
+				imap.CapStatusSize:   available.StatusSize,
+				//imap.CapBinary: available.Binary,
+				//imap.CapChildren: available.Children,
 			})
 		}
 
 		// Capabilities which require backend support and apply to both
 		// IMAP4rev1 and IMAP4rev2
-		addAvailableCaps(&caps, available, []imap.Cap{
-			imap.CapSpecialUse,
-			imap.CapCreateSpecialUse,
-			imap.CapLiteralPlus,
-			imap.CapUnauthenticate,
+		addAvailableCaps(&caps, map[imap.Cap]bool{
+			imap.CapSpecialUse:       available.SpecialUse,
+			imap.CapCreateSpecialUse: available.CreateSpecialUse,
+			imap.CapLiteralPlus:      available.LiteralPlus,
+			imap.CapUnauthenticate:   available.Unauthenticate,
 		})
 	}
 	return caps
 }
 
-func addAvailableCaps(caps *[]imap.Cap, available imap.CapSet, l []imap.Cap) {
-	for _, c := range l {
-		if available.Has(c) {
+func addAvailableCaps(caps *[]imap.Cap, available map[imap.Cap]bool) {
+	for c, ok := range available {
+		if ok {
 			*caps = append(*caps, c)
 		}
 	}

imapserver/server.go

@@ -21,6 +21,30 @@ type Logger interface {
 	Printf(format string, args ...interface{})
 }
 
+// SupportedCaps describes capabilities supported by the server.
+type SupportedCaps struct {
+	// IMAP protocol version
+	IMAP4rev1 bool // RFC 3501
+	IMAP4rev2 bool // RFC 9051
+
+	// Capabilities which are part of IMAP4rev2 and need to be explicitly
+	// enabled by IMAP4rev1-only servers
+	Namespace    bool // RFC 2342
+	UIDPlus      bool // RFC 4315
+	ESearch      bool // RFC 4731
+	ListExtended bool // RFC 5258
+	ListStatus   bool // RFC 5819
+	Move         bool // RFC 6851
+	StatusSize   bool // RFC 8438
+
+	// Capabilities which need to be explicitly enabled on both IMAP4rev1 and
+	// IMAP4rev2 servers
+	SpecialUse       bool // RFC 6154
+	CreateSpecialUse bool // RFC 6154
+	LiteralPlus      bool // RFC 7888
+	Unauthenticate   bool // RFC 8437
+}
+
 // Options contains server options.
 //
 // The only required field is NewSession.
@@ -29,18 +53,7 @@ type Options struct {
 	NewSession func(*Conn) (Session, *GreetingData, error)
 	// Supported capabilities. If nil, only IMAP4rev1 is advertised. This set
 	// must contain at least IMAP4rev1 or IMAP4rev2.
-	//
-	// The following capabilities are part of IMAP4rev2 and need to be
-	// explicitly enabled by IMAP4rev1-only servers:
-	//
-	//   - NAMESPACE
-	//   - UIDPLUS
-	//   - ESEARCH
-	//   - LIST-EXTENDED
-	//   - LIST-STATUS
-	//   - MOVE
-	//   - STATUS=SIZE
-	Caps imap.CapSet
+	Caps *SupportedCaps
 	// Logger is a logger to print error messages. If nil, log.Default is used.
 	Logger Logger
 	// TLSConfig is a TLS configuration for STARTTLS. If nil, STARTTLS is
@@ -68,11 +81,11 @@ func (options *Options) wrapReadWriter(rw io.ReadWriter) io.ReadWriter {
 	}
 }
 
-func (options *Options) caps() imap.CapSet {
+func (options *Options) caps() *SupportedCaps {
 	if options.Caps != nil {
 		return options.Caps
 	}
-	return imap.CapSet{imap.CapIMAP4rev1: {}}
+	return &SupportedCaps{IMAP4rev1: true}
 }
 
 // Server is an IMAP server.