BlockedExternalDomains: validate JSON structure before save

This makes raw page editing safer, and potentially enables opening up
access to less restricted user groups.

Bug: T337431
Change-Id: I14f21003a551f34b6e524e9b229613e79b0e5a70

extension.json

@@ -411,7 +411,8 @@
 		"BeforeCreateEchoEvent": "MediaWiki\\Extension\\AbuseFilter\\Hooks\\Handlers\\EchoHandler::onBeforeCreateEchoEvent",
 		"ParserOutputStashForEdit": "FilteredActions",
 		"UnitTestsAfterDatabaseSetup": "Tests",
-		"UnitTestsBeforeDatabaseTeardown": "Tests"
+		"UnitTestsBeforeDatabaseTeardown": "Tests",
+		"JsonValidateSave": "EditPermission"
 	},
 	"ServiceWiringFiles": [
 		"includes/ServiceWiring.php"

i18n/en.json

@@ -583,6 +583,8 @@
 	"abusefilter-blocked-domains-remove-reason": "Reason",
 	"abusefilter-blocked-domains-remove-submit": "Remove",
 	"abusefilter-blocked-domains-attempted": "The text you wanted to publish was blocked by our filter. The following domain is blocked from being added: $1",
+	"abusefilter-blocked-domains-json-error": "JSON should be an array",
+	"abusefilter-blocked-domains-invalid-entry": "Entry $1 in JSON is invalid - it should be an object with 'domain' and 'notes' fields only, both being strings",
 	"log-description-abusefilterprivatedetails": "This log shows a list of times when a user accessed the private details of an abuse log.",
 	"abusefilter-noreason": "Warning: To see the private details of this log, you must provide a reason.",
 	"abusefilter-log-ip-not-available": "Not Available",

i18n/qqq.json

@@ -625,6 +625,8 @@
 	"abusefilter-blocked-domains-remove-reason": "Reason given for removal",
 	"abusefilter-blocked-domains-remove-submit": "Submit button",
 	"abusefilter-blocked-domains-attempted": "The error message when adding a blocked domain has been attempted.",
+	"abusefilter-blocked-domains-json-error": "The error message when editing the JSON page to no longer be an array",
+	"abusefilter-blocked-domains-invalid-entry": "The error message when adding an invalid entry to the JSON array. Parameters:\n* $1 - the serial number of the entry which is invalid.",
 	"log-description-abusefilterprivatedetails": "The description of the abuse filter private details access log.",
 	"abusefilter-noreason": "Warning message shown when no reasons is given to access the private details of an abuse log.",
 	"abusefilter-log-ip-not-available": "Text shown when IP address is not available.\n{{Identical|Not available}}",

includes/Hooks/Handlers/EditPermissionHandler.php

@@ -3,18 +3,29 @@
 
 namespace MediaWiki\Extension\AbuseFilter\Hooks\Handlers;
 
+use JsonContent;
+use MediaWiki\Content\Hook\JsonValidateSaveHook;
 use MediaWiki\Extension\AbuseFilter\BlockedDomainStorage;
 use MediaWiki\MediaWikiServices;
+use MediaWiki\Page\PageIdentity;
 use MediaWiki\Permissions\Hook\GetUserPermissionsErrorsHook;
 use MessageSpecifier;
+use StatusValue;
 use Title;
+use TitleValue;
 use User;
 
 /**
  * This hook handler is for very simple checks, rather than the much more advanced ones
  * undertaken by the FilteredActionsHandler.
  */
-class EditPermissionHandler implements GetUserPermissionsErrorsHook {
+class EditPermissionHandler implements GetUserPermissionsErrorsHook, JsonValidateSaveHook {
+
+	/** @var string[] */
+	private const JSON_OBJECT_FIELDS = [
+		'domain',
+		'notes'
+	];
 
 	/**
 	 * @see https://www.mediawiki.org/wiki/Manual:Hooks/getUserPermissionsErrors
@@ -48,4 +59,52 @@ class EditPermissionHandler implements GetUserPermissionsErrorsHook {
 		return false;
 	}
 
+	/**
+	 * @param JsonContent $content
+	 * @param PageIdentity $pageIdentity
+	 * @param StatusValue $status
+	 * @return bool|void
+	 */
+	public function onJsonValidateSave( JsonContent $content, PageIdentity $pageIdentity, StatusValue $status ) {
+		$services = MediaWikiServices::getInstance();
+
+		// Only do anything if we're enabled on this wiki.
+		if ( !$services->getMainConfig()->get( 'AbuseFilterEnableBlockedExternalDomain' ) ) {
+			return;
+		}
+
+		$title = TitleValue::newFromPage( $pageIdentity );
+		if ( !$title->inNamespace( NS_MEDIAWIKI ) || $title->getText() !== BlockedDomainStorage::TARGET_PAGE ) {
+			return;
+		}
+		$data = $content->getData()->getValue();
+
+		if ( !is_array( $data ) ) {
+			$status->fatal( 'abusefilter-blocked-domains-json-error' );
+			return;
+		}
+
+		$isValid = true;
+		$entryNumber = 0;
+		foreach ( $data as $element ) {
+			$entryNumber++;
+			// Check if each element is an object with all known fields, and no other fields
+			if ( is_object( $element ) && count( get_object_vars( $element ) ) === count( self::JSON_OBJECT_FIELDS ) ) {
+				foreach ( self::JSON_OBJECT_FIELDS as $field ) {
+					if ( !property_exists( $element, $field ) || !is_string( $element->{$field} ) ) {
+						$isValid = false;
+						break 2;
+					}
+				}
+			} else {
+				$isValid = false;
+				break;
+			}
+		}
+
+		if ( !$isValid ) {
+			$status->fatal( 'abusefilter-blocked-domains-invalid-entry', $entryNumber );
+		}
+	}
+
 }