WIP: Http rework (#98)

- Move all HTTP tasks to a unified "MonitoredResource" model. This
   provides a uniform way of tracking object's lifetimes and disposing
   of them when complete.

 - Rewrite HTTP requests to use Netty instead of standard Java. This
   offers several advantages:
    - We have access to more HTTP verbs (mostly PATCH).
    - We can now do http -> https redirects.
    - We no longer need to spawn in a new thread for each HTTP request.
      While we do need to run some tasks off-thread in order to resolve
      IPs, it's generally a much shorter task, and so is less likely to
      inflate the thread pool.

 - Introduce several limits for the http API:
    - There's a limit on how many HTTP requests and websockets may exist
      at the same time. If the limit is reached, additional ones will be
      queued up until pending requests have finished.
    - HTTP requests may upload a maximum of 4Mib and download a maximum
      of 16Mib (configurable).

 - .getResponseCode now returns the status text, as well as the status
   code.

src/main/java/dan200/computercraft/shared/Config.java

@@ -11,6 +11,7 @@ import com.google.common.base.Converter;
 import dan200.computercraft.ComputerCraft;
 import dan200.computercraft.api.turtle.event.TurtleAction;
 import dan200.computercraft.core.apis.AddressPredicate;
+import dan200.computercraft.core.apis.http.websocket.Websocket;
 import net.minecraftforge.common.config.ConfigCategory;
 import net.minecraftforge.common.config.ConfigElement;
 import net.minecraftforge.common.config.Configuration;
@@ -35,11 +36,6 @@ public class Config
 
     private static Configuration config;
 
-    private static Property httpEnable;
-    private static Property httpWebsocketEnable;
-    private static Property httpWhitelist;
-    private static Property httpBlacklist;
-
     private static Property computerSpaceLimit;
     private static Property floppySpaceLimit;
     private static Property maximumFilesOpen;
@@ -49,12 +45,16 @@ public class Config
     private static Property computerThreads;
     private static Property logComputerErrors;
 
-    private static Property turtlesNeedFuel;
-    private static Property turtleFuelLimit;
-    private static Property advancedTurtleFuelLimit;
-    private static Property turtlesObeyBlockProtection;
-    private static Property turtlesCanPush;
-    private static Property turtleDisabledActions;
+    private static Property httpEnable;
+    private static Property httpWebsocketEnable;
+    private static Property httpWhitelist;
+    private static Property httpBlacklist;
+
+    private static Property httpMaxRequests;
+    private static Property httpMaxDownload;
+    private static Property httpMaxUpload;
+    private static Property httpMaxWebsockets;
+    private static Property httpMaxWebsocketMessage;
 
     private static Property commandBlockEnabled;
     private static Property modemRange;
@@ -63,6 +63,13 @@ public class Config
     private static Property modemHighAltitudeRangeDuringStorm;
     private static Property maxNotesPerTick;
 
+    private static Property turtlesNeedFuel;
+    private static Property turtleFuelLimit;
+    private static Property advancedTurtleFuelLimit;
+    private static Property turtlesObeyBlockProtection;
+    private static Property turtlesCanPush;
+    private static Property turtleDisabledActions;
+
     public static void load( File configFile )
     {
         config = new Configuration( configFile );
@@ -135,9 +142,31 @@ public class Config
                 "If this is empty then all whitelisted domains will be accessible. Example: \"*.github.com\" will block access to all subdomains of github.com.\n" +
                 "You can use domain names (\"pastebin.com\"), wilcards (\"*.pastebin.com\") or CIDR notation (\"127.0.0.0/8\")." );
 
+            httpMaxRequests = config.get( CATEGORY_HTTP, "max_requests", ComputerCraft.httpMaxRequests );
+            httpMaxRequests.setComment( "The number of http requests a computer can make at one time. Additional requests will be queued, and sent when the running requests have finished. Set to 0 for unlimited." );
+            httpMaxRequests.setMinValue( 0 );
+
+            httpMaxDownload = config.get( CATEGORY_HTTP, "max_download", (int) ComputerCraft.httpMaxDownload );
+            httpMaxDownload.setComment( "The maximum size (in bytes) that a computer can download in a single request. Note that responses may receive more data than allowed, but this data will not be returned to the client." );
+            httpMaxDownload.setMinValue( 0 );
+
+            httpMaxUpload = config.get( CATEGORY_HTTP, "max_upload", (int) ComputerCraft.httpMaxUpload );
+            httpMaxUpload.setComment( "The maximum size (in bytes) that a computer can upload in a single request. This includes headers and POST text." );
+            httpMaxUpload.setMinValue( 0 );
+
+            httpMaxWebsockets = config.get( CATEGORY_HTTP, "max_websockets", ComputerCraft.httpMaxWebsockets );
+            httpMaxWebsockets.setComment( "The number of websockets a computer can have open at one time. Set to 0 for unlimited." );
+            httpMaxWebsockets.setMinValue( 1 );
+
+            httpMaxWebsocketMessage = config.get( CATEGORY_HTTP, "max_websocket_message", ComputerCraft.httpMaxWebsocketMessage );
+            httpMaxWebsocketMessage.setComment( "The maximum size (in bytes) that a computer can send or receive in one websocket packet." );
+            httpMaxWebsocketMessage.setMinValue( 0 );
+            httpMaxWebsocketMessage.setMaxValue( Websocket.MAX_MESSAGE_SIZE );
+
             setOrder(
                 CATEGORY_HTTP,
-                httpEnable, httpWebsocketEnable, httpWhitelist, httpBlacklist
+                httpEnable, httpWebsocketEnable, httpWhitelist, httpBlacklist,
+                httpMaxRequests, httpMaxDownload, httpMaxUpload, httpMaxWebsockets, httpMaxWebsocketMessage
             );
         }
 
@@ -286,6 +315,12 @@ public class Config
         ComputerCraft.http_whitelist = new AddressPredicate( httpWhitelist.getStringList() );
         ComputerCraft.http_blacklist = new AddressPredicate( httpBlacklist.getStringList() );
 
+        ComputerCraft.httpMaxRequests = Math.max( 1, httpMaxRequests.getInt() );
+        ComputerCraft.httpMaxDownload = Math.max( 0, httpMaxDownload.getLong() );
+        ComputerCraft.httpMaxUpload = Math.max( 0, httpMaxUpload.getLong() );
+        ComputerCraft.httpMaxWebsockets = Math.max( 1, httpMaxWebsockets.getInt() );
+        ComputerCraft.httpMaxWebsocketMessage = Math.max( 0, httpMaxWebsocketMessage.getInt() );
+
         // Peripheral
         ComputerCraft.enableCommandBlock = commandBlockEnabled.getBoolean();
         ComputerCraft.maxNotesPerTick = Math.max( 1, maxNotesPerTick.getInt() );

src/main/java/dan200/computercraft/shared/computer/core/ClientComputer.java

@@ -64,6 +64,13 @@ public class ClientComputer extends ClientTerminal implements IComputer
         return m_instanceID;
     }
 
+    @Override
+    @Deprecated
+    public int getID()
+    {
+        return -1;
+    }
+
     @Override
     @Deprecated
     public String getLabel()

src/main/java/dan200/computercraft/shared/computer/core/IComputer.java

@@ -13,6 +13,9 @@ public interface IComputer extends ITerminal
 {
     int getInstanceID();
 
+    @Deprecated
+    int getID();
+
     @Deprecated
     String getLabel();
 

src/main/java/dan200/computercraft/shared/computer/core/ServerComputer.java

@@ -226,6 +226,8 @@ public class ServerComputer extends ServerTerminal implements IComputer, IComput
         return m_instanceID;
     }
 
+    @Override
+    @SuppressWarnings( "deprecation" )
     public int getID()
     {
         return m_computer.getID();

src/main/java/dan200/computercraft/shared/util/IDAssigner.java

@@ -9,6 +9,7 @@ package dan200.computercraft.shared.util;
 import dan200.computercraft.ComputerCraft;
 
 import java.io.*;
+import java.nio.charset.StandardCharsets;
 
 public class IDAssigner
 {
@@ -71,14 +72,7 @@ public class IDAssigner
             {
                 FileInputStream in = new FileInputStream( lastidFile );
                 InputStreamReader isr;
-                try
-                {
-                    isr = new InputStreamReader( in, "UTF-8" );
-                }
-                catch( UnsupportedEncodingException e )
-                {
-                    isr = new InputStreamReader( in );
-                }
+                isr = new InputStreamReader( in, StandardCharsets.UTF_8 );
                 try( BufferedReader br = new BufferedReader( isr ) )
                 {
                     idString = br.readLine();

src/main/java/dan200/computercraft/shared/util/IoUtil.java

@@ -0,0 +1,24 @@
+/*
+ * This file is part of ComputerCraft - http://www.computercraft.info
+ * Copyright Daniel Ratcliffe, 2011-2019. Do not distribute without permission.
+ * Send enquiries to dratcliffe@gmail.com
+ */
+
+package dan200.computercraft.shared.util;
+
+import java.io.Closeable;
+import java.io.IOException;
+
+public class IoUtil
+{
+    public static void closeQuietly( Closeable closeable )
+    {
+        try
+        {
+            closeable.close();
+        }
+        catch( IOException ignored )
+        {
+        }
+    }
+}