add user cache to keep track of each user's last 10 (at most) known u…

…sernames add command /whitelist list add command /blacklist list optimize command output /bungeesafeguard dump avoid triggering a bug of BungeeCord where the LoginEvent cannot be cancelled properly with null cancel reason
Luluno01 · Apr 11, 2021 · 36d8b27 · 36d8b27
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diff --git a/.idea/BungeeGuard.iml b/.idea/BungeeGuard.iml
diff --git a/.idea/artifacts/BungeeSafeguard_main_jar.xml b/.idea/artifacts/BungeeSafeguard_main_jar.xml
diff --git a/README.md b/README.md
@@ -4,7 +4,7 @@ A blacklist and whitelist BungeeCord plugin with support of UUID look up.
 
 This plugin was formerly named BungeeGuard. In order not to conflict with the existing plugin BungeeGuard, this plugin is renamed to BungeeSafeguard from v2.0.
 
-Tested on Waterfall, version: `git:Waterfall-Bootstrap:1.16-R0.4-SNAPSHOT:1d2221d:384`.
+Tested on Waterfall, version: `git:Waterfall-Bootstrap:1.16-R0.5-SNAPSHOT:454f9d4:404`.
 
 - [BungeeSafeguard](#bungeesafeguard)
   - [Features](#features)
@@ -24,6 +24,7 @@ Tested on Waterfall, version: `git:Waterfall-Bootstrap:1.16-R0.4-SNAPSHOT:1d2221
       - [whitelist on](#whitelist-on)
       - [whitelist off](#whitelist-off)
       - [whitelist confirm](#whitelist-confirm)
+      - [whitelist list](#whitelist-list)
     - [Blacklist](#blacklist)
       - [blacklist add](#blacklist-add)
       - [blacklist x-add](#blacklist-x-add)
@@ -35,6 +36,7 @@ Tested on Waterfall, version: `git:Waterfall-Bootstrap:1.16-R0.4-SNAPSHOT:1d2221
       - [blacklist on](#blacklist-on)
       - [blacklist off](#blacklist-off)
       - [blacklist confirm](#blacklist-confirm)
+      - [blacklist list](#blacklist-list)
     - [Main Command](#main-command)
       - [bungeesafeguard load](#bungeesafeguard-load)
       - [bungeesafeguard reload](#bungeesafeguard-reload)
@@ -93,12 +95,12 @@ The configuration file for BungeeSafeguard is `plugins/BungeeSafeguard/config.ym
 ```yaml
 #########################################
 #     BungeeSafeguard Configuration     #
-#            Version: 2.5               #
+#            Version: 2.6               #
 #          Author: Untitled             #
 #########################################
 
 # You can safely ignore this
-version: "2.5"
+version: "2.6"
 
 # Message to be sent to the player when that player is blocked for not being whitelisted
 whitelist-message: :( You are not whitelisted on this server
@@ -287,6 +289,31 @@ Confirm the last issued whitelist command:
 whitelist confirm
 ```
 
+#### whitelist list
+
+Alias: `whitelist ls`, `whitelist show` or `whitelist dump`.
+
+Dump whitelist and lazy whitelist with at most 10 last known usernames:
+
+```
+whitelist list
+```
+
+Example output:
+
+```
+Whitelist ENABLED
+2 lazy record(s)
+  foo
+  bar
+3 UUID record(s) and the last known names (in reverse chronological order)
+  00000000-1111-2222-3333-666666666666 LatestName, OldNameLastMonth, OldNameLastYear
+  ffffffff-1111-2222-3333-666666666666
+  eeeeeeee-1111-2222-3333-666666666666 LatestName123
+```
+
+*This feature is added as requested by issue #8.*
+
 ### Blacklist
 
 Alias: `blist`.
@@ -428,6 +455,31 @@ Confirm the last issued blacklist command:
 blacklist confirm
 ```
 
+#### blacklist list
+
+Alias: `blacklist ls`, `blacklist show` or `blacklist dump`.
+
+Dump blacklist and lazy blacklist with at most 10 last known usernames:
+
+```
+whitelist list
+```
+
+Example output:
+
+```
+Blacklist ENABLED
+2 lazy record(s)
+  foo
+  bar
+3 UUID record(s) and the last known names (in reverse chronological order)
+  00000000-1111-2222-3333-666666666666 LatestName, OldNameLastMonth, OldNameLastYear
+  ffffffff-1111-2222-3333-666666666666
+  eeeeeeee-1111-2222-3333-666666666666 LatestName123
+```
+
+*This feature is added as requested by issue #8.*
+
 ### Main Command
 
 Alias: `bsg`.
@@ -517,3 +569,5 @@ BungeeSafeguard does asynchronous UUID look up when you execute add/remove on th
 It's recommended to execute those command only in console, and wait patiently for the completion feedback from the command before executing other commands of BungeeSafeguard.
 
 Offline servers should be able to use this plugin by using lazy lists or supplying BungeeSafeguard with players' UUIDs rather than their usernames. However, offline servers are still suffering from UUID abuse if they have no authentication plugin installed or have no external authentication mechanism. Offline server owners need to fully understand whitelist and blacklist is **NOT** a prevention of UUID abuse.
+
+Last but not least, you should always be prepared for the worst situation, for example, when BungeeCord or BungeeSafeguard somehow, magically, fail to protect your servers. Backup is a good way to counter Murphy's law.
diff --git a/build.gradle b/build.gradle
@@ -1,10 +1,10 @@
 plugins {
     id 'java'
-    id 'org.jetbrains.kotlin.jvm' version '1.4.20'
+    id 'org.jetbrains.kotlin.jvm' version '1.4.32'
 }
 
 group 'vip.untitled'
-version '2.5-SNAPSHOT'
+version '2.6-SNAPSHOT'
 
 sourceCompatibility = 1.8
 
@@ -18,7 +18,7 @@ repositories {
 dependencies {
     implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk8"
     implementation 'com.google.code.gson:gson:2.8.6'
-    compileOnly "net.md-5:bungeecord-api:1.16-R0.4-SNAPSHOT"
+    compileOnly "net.md-5:bungeecord-api:1.16-R0.5-SNAPSHOT"
     testCompile group: 'junit', name: 'junit', version: '4.12'
 }
 

diff --git a/src/main/kotlin/vip/untitled/bungeesafeguard/BungeeSafeguard.kt b/src/main/kotlin/vip/untitled/bungeesafeguard/BungeeSafeguard.kt
@@ -9,7 +9,7 @@ import java.io.IOException
 
 
 @Suppress("unused")
-open class BungeeSafeguard: ConfigHolderPlugin() {
+open class BungeeSafeguard: MetaHolderPlugin() {
     internal lateinit var events: Events
     private lateinit var whitelistCommand: Whitelist
     private lateinit var blacklistCommand: Blacklist
@@ -19,6 +19,7 @@ open class BungeeSafeguard: ConfigHolderPlugin() {
         proxy.pluginManager.registerListener(this, events)
 
         loadConfig(null)
+        loadUserCache()
         whitelistCommand = Whitelist(this)
         proxy.pluginManager.registerCommand(this, whitelistCommand)
         blacklistCommand = Blacklist(this)
@@ -77,6 +78,10 @@ open class BungeeSafeguard: ConfigHolderPlugin() {
         config.reload(sender)
     }
 
+    open fun reloadUserCache() {
+        userCache.reload()
+    }
+
     open fun loadConfig(sender: CommandSender?) {
         config = Config(this)
         try {
@@ -85,4 +90,13 @@ open class BungeeSafeguard: ConfigHolderPlugin() {
             logger.warning("Unable to read config file \"${config.configInUse}\", please check the config file and if the content of \"${Config.CONFIG_IN_USE}\" is correct")
         }
     }
+
+    open fun loadUserCache() {
+        userCache = UserCache(this)
+        try {
+            userCache.load()
+        } catch (err: IOException) {
+            logger.warning("Unable to read user cache file \"${UserCache.CACHE_FILE}\", please check the user cache file or simply delete it")
+        }
+    }
 }
diff --git a/src/main/kotlin/vip/untitled/bungeesafeguard/Events.kt b/src/main/kotlin/vip/untitled/bungeesafeguard/Events.kt
@@ -9,15 +9,15 @@ import net.md_5.bungee.api.plugin.Listener
 import net.md_5.bungee.event.EventHandler
 import java.util.*
 
-open class Events(val context: ConfigHolderPlugin): Listener {
+open class Events(val context: MetaHolderPlugin): Listener {
     protected val config: Config
         get() = context.config
-    protected val whitelistMessage: String?
-        get() = config.whitelistMessage
-    protected val blacklistMessage: String?
-        get() = config.blacklistMessage
-    protected val noUUIDMessage: String?
-        get() = config.noUUIDMessage
+    protected val whitelistMessage: String
+        get() = config.whitelistMessage ?: ""
+    protected val blacklistMessage: String
+        get() = config.blacklistMessage ?: ""
+    protected val noUUIDMessage: String
+        get() = config.noUUIDMessage ?: ""
     protected val enableWhitelist: Boolean
         get() = config.enableWhitelist
     protected val enableBlacklist: Boolean
@@ -55,6 +55,27 @@ open class Events(val context: ConfigHolderPlugin): Listener {
         return KickReason.DO_NOT_KICK
     }
 
+    /**
+     * Update user cache
+     *
+     * We only care about the usernames of users in the whitelist or the blacklist
+     *
+     * This should be called AFTER `shouldKick`, who might update the two lists,
+     * because this method will check if the user is in one of the two lists
+     *
+     * @param id User's UUID
+     * @param username Username
+     */
+    open fun updateUserCache(id: UUID, username: String) {
+        val cache = context.userCache
+        if (config.inWhitelist(id) || config.inBlacklist(id)) {
+            cache.addAndSave(id, username)
+        } else if (cache.contains(id)) {
+            // Somehow this user is in the cache
+            cache.removeAndSave(id)  // We don't need to know the username of this user anymore
+        }
+    }
+
     @EventHandler
     open fun onPostLogin(event: PostLoginEvent) {
         val player = event.player
@@ -63,16 +84,15 @@ open class Events(val context: ConfigHolderPlugin): Listener {
         when (shouldKick(username, id)) {
             KickReason.DO_NOT_KICK -> {}
             KickReason.BLACKLISTED -> {
-                if (blacklistMessage == null) player.disconnect()
-                else player.disconnect(TextComponent(blacklistMessage))
+                player.disconnect(TextComponent(blacklistMessage))
                 context.logger.info("Banned player ${ChatColor.RED}${username} ${ChatColor.BLUE}(${id})${ChatColor.RESET} blocked!")
             }
             KickReason.NOT_WHITELISTED -> {
-                if (whitelistMessage == null) player.disconnect()
-                else player.disconnect(TextComponent(whitelistMessage))
+                player.disconnect(TextComponent(whitelistMessage))
                 context.logger.info("Non-whitelisted player ${ChatColor.AQUA}${username} ${ChatColor.BLUE}(${id})${ChatColor.RESET} blocked!")
             }
         }
+        updateUserCache(id, username)
     }
 
     @EventHandler
@@ -81,24 +101,25 @@ open class Events(val context: ConfigHolderPlugin): Listener {
         val username = connection.name
         val id = connection.uniqueId
         if (id == null) {
-            if (noUUIDMessage != null) event.setCancelReason(TextComponent(noUUIDMessage))
+            event.setCancelReason(TextComponent(noUUIDMessage))
             event.isCancelled = true
             context.logger.info("${ChatColor.YELLOW}Player ${ChatColor.RED}${username} ${ChatColor.YELLOW}has no UUID, blocked for safety")
             return
         }
         when (shouldKick(username, id)) {
             KickReason.DO_NOT_KICK -> {}
             KickReason.BLACKLISTED -> {
-                if (blacklistMessage != null) event.setCancelReason(TextComponent(blacklistMessage))
+                event.setCancelReason(TextComponent(blacklistMessage))
                 event.isCancelled = true
                 context.logger.info("Banned player ${ChatColor.RED}${username} ${ChatColor.BLUE}(${id})${ChatColor.RESET} blocked from logging in!")
             }
             KickReason.NOT_WHITELISTED -> {
-                if (whitelistMessage != null) event.setCancelReason(TextComponent(whitelistMessage))
+                event.setCancelReason(TextComponent(whitelistMessage))
                 event.isCancelled = true
                 context.logger.info("Non-whitelisted player ${ChatColor.AQUA}${username} ${ChatColor.BLUE}(${id})${ChatColor.RESET} blocked from logging in!")
             }
         }
+        updateUserCache(id, username)
     }
 
     @EventHandler
@@ -110,16 +131,15 @@ open class Events(val context: ConfigHolderPlugin): Listener {
             KickReason.DO_NOT_KICK -> {}
             KickReason.BLACKLISTED -> {
                 event.isCancelled = true
-                if (blacklistMessage == null) player.disconnect()
-                else player.disconnect(TextComponent(blacklistMessage))
+                player.disconnect(TextComponent(blacklistMessage))
                 context.logger.info("Banned player ${ChatColor.RED}${username} ${ChatColor.BLUE}(${id})${ChatColor.RESET} blocked from connecting to server ${ChatColor.GREEN}${event.target.name}!")
             }
             KickReason.NOT_WHITELISTED -> {
                 event.isCancelled = true
-                if (whitelistMessage == null) player.disconnect()
-                else player.disconnect(TextComponent(whitelistMessage))
+                player.disconnect(TextComponent(whitelistMessage))
                 context.logger.info("Non-whitelisted player ${ChatColor.AQUA}${username} ${ChatColor.BLUE}(${id})${ChatColor.RESET} blocked from connecting to server ${ChatColor.GREEN}${event.target.name}!")
             }
         }
+        updateUserCache(id, username)
     }
 }
diff --git a/...led/bungeesafeguard/ConfigHolderPlugin.kt → ...itled/bungeesafeguard/MetaHolderPlugin.kt b/...led/bungeesafeguard/ConfigHolderPlugin.kt → ...itled/bungeesafeguard/MetaHolderPlugin.kt
@@ -2,6 +2,7 @@ package vip.untitled.bungeesafeguard
 
 import net.md_5.bungee.api.plugin.Plugin
 
-abstract class ConfigHolderPlugin: Plugin() {
+abstract class MetaHolderPlugin: Plugin() {
     lateinit var config: Config
+    lateinit var userCache: UserCache
 }