Fixes a SharedDirectoryAnnounce incompatibility

lib/srv/desktop/tdp/proto.go

@@ -667,6 +667,8 @@ type SharedDirectoryAnnounce struct {
 func (s SharedDirectoryAnnounce) Encode() ([]byte, error) {
 	buf := new(bytes.Buffer)
 	buf.WriteByte(byte(TypeSharedDirectoryAnnounce))
+	// TODO(isaiah): The discard here allows fuzz tests to succeed, it should eventually be done away with.
+	writeUint32(buf, 0) // discard
 	writeUint32(buf, s.DirectoryID)
 	if err := encodeString(buf, s.Name); err != nil {
 		return nil, trace.Wrap(err)
@@ -675,8 +677,16 @@ func (s SharedDirectoryAnnounce) Encode() ([]byte, error) {
 }
 
 func decodeSharedDirectoryAnnounce(in io.Reader) (SharedDirectoryAnnounce, error) {
+	// TODO(isaiah): The discard here is a copy-paste error, but we need to keep it
+	// for now in order that the proxy stay compatible with previous versions of the wds.
+	var discard uint32
+	err := binary.Read(in, binary.BigEndian, &discard)
+	if err != nil {
+		return SharedDirectoryAnnounce{}, trace.Wrap(err)
+	}
+
 	var directoryID uint32
-	err := binary.Read(in, binary.BigEndian, &directoryID)
+	err = binary.Read(in, binary.BigEndian, &directoryID)
 	if err != nil {
 		return SharedDirectoryAnnounce{}, trace.Wrap(err)
 	}

web/packages/teleport/src/lib/tdp/client.ts

@@ -513,7 +513,7 @@ export default class Client extends EventEmitterWebAuthnSender {
       name = this.sdManager.getName();
       this.send(
         this.codec.encodeSharedDirectoryAnnounce({
-          completionId: 0, // This is always the first request.
+          discard: 0, // This is always the first request.
           // Hardcode directoryId for now since we only support sharing 1 directory.
           // We're using 2 because the smartcard device is hardcoded to 1 in the backend.
           directoryId: 2,

web/packages/teleport/src/lib/tdp/codec.ts

@@ -132,8 +132,10 @@ export type MfaJson = {
 };
 
 // | message type (11) | completion_id uint32 | directory_id uint32 | name_length uint32 | name []byte |
+// TODO(isaiah): The discard here is a copy-paste error, but we need to keep it
+// for now in order that the proxy stay compatible with previous versions of the wds.
 export type SharedDirectoryAnnounce = {
-  completionId: number;
+  discard: number;
   directoryId: number;
   name: string;
 };
@@ -601,7 +603,9 @@ export default class Codec {
     let offset = 0;
 
     view.setUint8(offset++, MessageType.SHARED_DIRECTORY_ANNOUNCE);
-    view.setUint32(offset, sharedDirAnnounce.completionId);
+    // TODO(isaiah): The discard here is a copy-paste error, but we need to keep it
+    // for now in order that the proxy stay compatible with previous versions of the wds.
+    view.setUint32(offset, sharedDirAnnounce.discard);
     offset += uint32Length;
     view.setUint32(offset, sharedDirAnnounce.directoryId);
     offset += uint32Length;