fix: different approach IS#923

Author: Michaelgathara

Sources/SocketForwarder/ConnectHandler.swift

@@ -22,7 +22,6 @@ final class ConnectHandler {
     private var pendingBytes: [NIOAny]
     private let serverAddress: SocketAddress
     private var log: Logger? = nil
-    private var removed = false
 
     init(serverAddress: SocketAddress, log: Logger?) {
         self.pendingBytes = []
@@ -54,7 +53,6 @@ extension ConnectHandler: ChannelInboundHandler {
 
 extension ConnectHandler: RemovableChannelHandler {
     func removeHandler(context: ChannelHandlerContext, removalToken: ChannelHandlerContext.RemovalToken) {
-        self.removed = true
         var didRead = false
 
         // We are being removed, and need to deliver any pending bytes we may have if we're upgrading.
@@ -81,15 +79,13 @@ extension ConnectHandler {
             .connect(to: serverAddress)
             .assumeIsolatedUnsafeUnchecked()
             .whenComplete { result in
-                guard !self.removed else {
-                    if case .success(let channel) = result {
-                        channel.close(promise: nil)
-                    }
-                    return
-                }
-
                 switch result {
                 case .success(let channel):
+                    guard context.channel.isActive else {
+                        self.log?.trace("backend - frontend channel closed, closing backend connection")
+                        channel.close(promise: nil)
+                        return
+                    }
                     self.log?.trace("backend - connected")
                     self.glue(channel, context: context)
                 case .failure(let error):