[Chromoting] Add a simple Windows app that registers and starts a host.

remoting/host/setup/pin_validator.cc

+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "remoting/host/setup/pin_validator.h"
+
+namespace remoting {
+
+bool IsPinValid(const std::string& pin) {
+  if (pin.length() < 6) {
+    return false;
+  }
+  for (size_t i = 0; i < pin.length(); i++) {
+    char c = pin[i];
+    if (c < '0'  || c > '9') {

[alexeypa (please no reviews), 2012/10/11 16:57:52]

This code is not i18n-friendly. Should we treat |pin| as UTF-8 string? If yes,
we, probably, should classify characters using  Unicode character classes.

BTW: isdigit() is still better even if we go ahead with ASCII pins.

[simonmorris, 2012/10/11 21:27:35]

I don't want users to enter anything but plain old digits, because of the scope
for confusion. So I regard any character outside the range '0' to '9' as
invalid.

isdigit() has a locale-dependent definition, if <locale> is included, which
doesn't seem appropriate here.

+      return false;
+    }
+  }
+  return true;
+}
+
+}  // namespace remoting