Add lease-bound Remote key IPC and SDK validation

sdk/python/cthulhu_tentacle/session.py

@@ -102,6 +102,45 @@ def valid_remote_presentation(request):
         return False
 
 
+def valid_remote_key(key):
+    """Validate one logical key identity and transition, without desktop access."""
+    try:
+        _fields(key, ("name", "pressed"))
+        name = key["name"]
+        if not isinstance(name, str) or type(key["pressed"]) is not bool:
+            return False
+        if len(name) == 1 and name in "abcdefghijklmnopqrstuvwxyz0123456789":
+            return True
+        if (2 <= len(name) <= 3 and name[0] == "F" and name[1:].isascii()
+                and name[1:].isdecimal()):
+            number = int(name[1:])
+            return 1 <= number <= 24 and str(number) == name[1:]
+        if len(name) == 4 and name[:3] == "KP_" and name[3] in "0123456789":
+            return True
+        return name in (
+            "BackSpace", "Tab", "Return", "Escape", "space", "Pause", "Print", "Menu",
+            "Caps_Lock", "Num_Lock", "Scroll_Lock", "Shift_L", "Shift_R", "Control_L", "Control_R",
+            "Alt_L", "Alt_R", "Super_L", "Super_R", "Page_Up", "Page_Down", "End", "Home",
+            "Left", "Up", "Right", "Down", "Insert", "Delete",
+            "KP_Begin", "KP_Enter", "KP_Page_Up", "KP_Page_Down", "KP_End", "KP_Home",
+            "KP_Left", "KP_Up", "KP_Right", "KP_Down", "KP_Insert", "KP_Delete",
+            "KP_Multiply", "KP_Add", "KP_Separator", "KP_Subtract", "KP_Decimal", "KP_Divide",
+            "semicolon", "equal", "comma", "minus", "period", "slash", "grave", "bracketleft",
+            "backslash", "bracketright", "apostrophe")
+    except (ProtocolError, TypeError, ValueError):
+        return False
+
+
+def valid_remote_key_request(request):
+    """Validate remote.key parameters; consent and delivery checks belong to core."""
+    try:
+        _fields(request, ("lease", "epoch", "sequence", "key"))
+        return (_token(request["lease"]) and _positive(request["epoch"])
+                and _positive(request["sequence"]) and valid_remote_key(request["key"]))
+    except (ProtocolError, TypeError, ValueError, UnicodeError):
+        return False
+
+
 class SessionError(Exception):
     def __init__(self, code, message):
         super().__init__("Tentacle session error " + str(code))