Revert "Merge pull request #132 from eddc005/feat-pcap"

This reverts commit c453020349, reversing
changes made to 5723490a6c.

io/interface.go

@@ -48,9 +48,6 @@ type PacketIO interface {
 	ProtectedDialContext(ctx context.Context, network, address string) (net.Conn, error)
 	// Close closes the packet IO.
 	Close() error
-	// SetCancelFunc gives packet IO access to context cancel function, enabling it to
-	// trigger a shutdown
-	SetCancelFunc(cancelFunc context.CancelFunc) error
 }
 
 type ErrInvalidPacket struct {