netstack: make TCP endpoint closed and error state cleanup work synchronous.

So that when saving TCP endpoint in these states, there is no pending or
background activities.

Also lift tcp network save rejection error to tcpip package.

PiperOrigin-RevId: 199370748
Change-Id: Ief7b45c2a7338d12414cd7c23db95de6a9c22700

1 files changed, 11 insertions, 0 deletions

diff --git a/pkg/tcpip/tcpip.go b/pkg/tcpip/tcpip.go
index fdeba6bc4..cf25a086d 100644
--- a/pkg/tcpip/tcpip.go
+++ b/pkg/tcpip/tcpip.go
@@ -85,6 +85,17 @@ var (
 	errSubnetAddressMasked  = errors.New("subnet address has bits set outside the mask")
 )
 
+// ErrSaveRejection indicates a failed save due to unsupported networking state.
+// This type of errors is only used for save logic.
+type ErrSaveRejection struct {
+	Err error
+}
+
+// Error returns a sensible description of the save rejection error.
+func (e ErrSaveRejection) Error() string {
+	return "save rejected due to unsupported networking state: " + e.Err.Error()
+}
+
 // A Clock provides the current time.
 //
 // Times returned by a Clock should always be used for application-visible