[Password] Add clearPassword command

As suggested here: https://github.com/letscontrolit/ESPEasy/issues/3860

docs/source/Plugin/P000_commands.repl

@@ -50,6 +50,14 @@
     See also ``AccessInfo``.
 
     ``ClearAccessBlock``"
+    
+    "
+    ClearPassword","
+    :red:`Internal`","
+    Clear the password of the unit.
+    See also ``Password``.
+
+    ``ClearPassword,<current password>``"
     "
     ClearRTCram","
     :red:`Internal`","
@@ -287,7 +295,8 @@
     "
     Password","
     :red:`Internal`","
-    Set the password of the unit
+    Set the password of the unit.
+    See also ``ClearPassword``.
 
     ``Password,<new password>``"
     "

src/src/Commands/InternalCommands.cpp

@@ -268,6 +268,7 @@ bool executeInternalCommand(command_case_data & data)
     }
     case 'c': {
       COMMAND_CASE_R( "clearaccessblock", Command_AccessInfo_Clear,   0); // Network Command
+      COMMAND_CASE_R(     "clearpasword", Command_Settings_Password_Clear,     1); // Settings.h
       COMMAND_CASE_R(      "clearrtcram", Command_RTC_Clear,          0); // RTC.h
       COMMAND_CASE_R(           "config", Command_Task_RemoteConfig, -1); // Tasks.h
       COMMAND_CASE_R("controllerdisable", Command_Controller_Disable, 1); // Controller.h

src/src/Commands/Settings.cpp

@@ -62,6 +62,20 @@ String Command_Settings_Password(struct EventStruct *event, const char* Line)
 				      );
 }
 
+String Command_Settings_Password_Clear(struct EventStruct *event, const char* Line)
+{
+	const String storedPassword = SecuritySettings.getPassword();
+	if (storedPassword.length() > 0) {
+		// There is a password set, so we must check it.
+		const String password = parseStringKeepCase(Line, 2);
+		if (!storedPassword.equals(password)) {
+			return return_command_failed();
+		}
+        ZERO_FILL(SecuritySettings.Password);
+	}
+	return return_command_success();
+}
+
 const __FlashStringHelper * Command_Settings_Save(struct EventStruct *event, const char* Line)
 {
 	SaveSettings();

src/src/Commands/Settings.h

@@ -7,6 +7,7 @@ String Command_Settings_Build(struct EventStruct *event, const char* Line);
 String Command_Settings_Unit(struct EventStruct *event, const char* Line);
 String Command_Settings_Name(struct EventStruct *event, const char* Line);
 String Command_Settings_Password(struct EventStruct *event, const char* Line);
+String Command_Settings_Password_Clear(struct EventStruct *event, const char* Line);
 const __FlashStringHelper * Command_Settings_Save(struct EventStruct *event, const char* Line);
 const __FlashStringHelper * Command_Settings_Load(struct EventStruct *event, const char* Line);
 const __FlashStringHelper * Command_Settings_Print(struct EventStruct *event, const char* Line);

src/src/DataStructs/SecurityStruct.cpp

@@ -68,3 +68,13 @@ bool SecurityStruct::hasWiFiCredentials(SecurityStruct::WiFiCredentialsSlot slot
   }
   return false;
 }
+
+String SecurityStruct::getPassword() const {
+  String res;
+  const size_t passLength = strnlen(Password, sizeof(Password));
+  res.reserve(passLength);
+  for (size_t i = 0; i < passLength; ++i) {
+    res += Password[i];
+  }
+  return res;
+}

src/src/DataStructs/SecurityStruct.h

@@ -27,6 +27,8 @@ struct SecurityStruct
 
   bool hasWiFiCredentials(WiFiCredentialsSlot slot) const;
 
+  String getPassword() const;
+
   char          WifiSSID[32];
   char          WifiKey[64];
   char          WifiSSID2[32];