contaisTraversalCharacters is a extension for String to check when a path may contains an traversal path include attack for Swift 3.0

TraversalCharactersString.swift

/*
  Avoid usage of files with this characters.
  Examples with positive response:
    /var/www/templates/../../../etc/passwd
    /var/www/templates/%2e%2e%2f%2e%2e%2f%2e%2e%2fetc/passwd
    /var/www/templates%252e%252e%252f%252e%252e%252f%252e%252e%252fetc/passwd
    /var/www/templates/..%c0%af..%c0%af..%c0%afetc/passwd

  With this you cannot do things like this:
    /var/www/templates/.htdocs   (because /. is not allowed)

  Please, if you see any error or missing character, please let me know it!!.

*/
extension String {
    var containsTraversalCharacters: Bool {
        get {
            return traversalCharacters.count > 0
        }
    }
    
    var traversalCharacters: [String] {
        get {
            let dangerCharacters = ["%2e", "%2f", "%5c", "%252e", "%252f", "%255c", "%c0%af", "%c1%9c", ":", ">", "<", "./", ".\\", "..", "\\\\", "//", "/.", "\\.", "|"]
            return dangerCharacters.filter { contains($0) }.flatMap { $0 }
        }
    }
}