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Avoid Netty buffer leak in LegacyPingHandler. Fixes #1200 (#1201)

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The extra buffer used to decode the strings sent by the client
in the legacy ping protocol was never released. However, creating
an extra copy of the buffer just to decode it to a string isn't
actually necessary: We can just call toString() directly on the
original buffer.

Additionally, free the buffer in handlerRemoved() to handle cases
where the client never sends enough bytes to form a valid legacy
ping request.
This commit is contained in:
Minecrell 2018-07-13 09:43:56 +02:00 committed by Zach
parent 5b02e5736a
commit 81688d28d2
2 changed files with 37 additions and 21 deletions
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52
Spigot-Server-Patches/0284-Make-the-legacy-ping-handler-more-reliable.patch → Spigot-Server-Patches/0284-Make-legacy-ping-handler-more-reliable.patch
View file

@ -1,7 +1,7 @@
From e24f4a9cce13be40d11613acdfa591bcaa64fdd2 Mon Sep 17 00:00:00 2001
From 342fd0abbc9127651a9aafabe10a7b2afa2bf98d Mon Sep 17 00:00:00 2001
From: Minecrell <minecrell@minecrell.net>
Date: Wed, 11 Oct 2017 18:22:50 +0200
Subject: [PATCH] Make the legacy ping handler more reliable
Subject: [PATCH] Make legacy ping handler more reliable
The Minecraft server often fails to respond to old ("legacy") pings
from old Minecraft versions using the protocol used before the switch
@ -28,7 +28,7 @@ respond to the request.
[2]: https://netty.io/wiki/user-guide-for-4.x.html#wiki-h4-13
diff --git a/src/main/java/net/minecraft/server/LegacyPingHandler.java b/src/main/java/net/minecraft/server/LegacyPingHandler.java
index 4c1a0181a..f084a653a 100644
index 4c1a0181a..a89a86e6d 100644
--- a/src/main/java/net/minecraft/server/LegacyPingHandler.java
+++ b/src/main/java/net/minecraft/server/LegacyPingHandler.java
@@ -14,6 +14,7 @@ public class LegacyPingHandler extends ChannelInboundHandlerAdapter {
@ -77,11 +77,22 @@ index 4c1a0181a..f084a653a 100644
}
bytebuf.release();
@@ -92,6 +108,74 @@ public class LegacyPingHandler extends ChannelInboundHandlerAdapter {
@@ -92,6 +108,90 @@ public class LegacyPingHandler extends ChannelInboundHandlerAdapter {
}
+ // Paper start
+ private static String readLegacyString(ByteBuf buf) {
+ int size = buf.readShort() * Character.BYTES;
+ if (!buf.isReadable(size)) {
+ return null;
+ }
+
+ String result = buf.toString(buf.readerIndex(), size, StandardCharsets.UTF_16BE);
+ buf.skipBytes(size); // toString doesn't increase readerIndex automatically
+ return result;
+ }
+
+ private void readLegacy1_6(ChannelHandlerContext ctx, ByteBuf part) {
+ ByteBuf buf = this.buf;
+
@ -94,34 +105,31 @@ index 4c1a0181a..f084a653a 100644
+
+ buf.writeBytes(part);
+
+ // Short + Short + Byte + Short + Int
+ if (!buf.isReadable(2 + 2 + 1 + 2 + 4)) {
+ if (!buf.isReadable(Short.BYTES + Short.BYTES + Byte.BYTES + Short.BYTES + Integer.BYTES)) {
+ return;
+ }
+
+ short length = buf.readShort();
+ if (!buf.isReadable(length * 2)) {
+ String s = readLegacyString(buf);
+ if (s == null) {
+ return;
+ }
+
+ if (!buf.readBytes(length * 2).toString(StandardCharsets.UTF_16BE).equals("MC|PingHost")) {
+ if (!s.equals("MC|PingHost")) {
+ removeHandler(ctx);
+ return;
+ }
+
+ if (!buf.isReadable(2)) {
+ return;
+ }
+
+ length = buf.readShort();
+ if (!buf.isReadable(length)) {
+ if (!buf.isReadable(Short.BYTES) || !buf.isReadable(buf.readShort())) {
+ return;
+ }
+
+ MinecraftServer server = this.b.d();
+ int protocolVersion = buf.readByte();
+ length = buf.readShort();
+ String host = buf.readBytes(length * 2).toString(StandardCharsets.UTF_16BE);
+ String host = readLegacyString(buf);
+ if (host == null) {
+ removeHandler(ctx);
+ return;
+ }
+ int port = buf.readInt();
+
+ if (buf.isReadable()) {
@ -144,9 +152,17 @@ index 4c1a0181a..f084a653a 100644
+ this.buf = null;
+
+ buf.resetReaderIndex();
+ ctx.pipeline().remove("legacy_query");
+ ctx.pipeline().remove(this);
+ ctx.fireChannelRead(buf);
+ }
+
+ @Override
+ public void handlerRemoved(ChannelHandlerContext ctx) {
+ if (this.buf != null) {
+ this.buf.release();
+ this.buf = null;
+ }
+ }
+ // Paper end
+
private void a(ChannelHandlerContext channelhandlercontext, ByteBuf bytebuf) {

6
Spigot-Server-Patches/0285-Call-PaperServerListPingEvent-for-legacy-pings.patch
View file

@ -1,4 +1,4 @@
From 93caa0bf416f61fe9f92a45a4631900b78e939dc Mon Sep 17 00:00:00 2001
From fdff041cd1df94bc3a0173545b6e171c3cdf4579 Mon Sep 17 00:00:00 2001
From: Minecrell <minecrell@minecrell.net>
Date: Wed, 11 Oct 2017 19:30:51 +0200
Subject: [PATCH] Call PaperServerListPingEvent for legacy pings
@ -84,7 +84,7 @@ index 000000000..74c012fd4
+
+}
diff --git a/src/main/java/net/minecraft/server/LegacyPingHandler.java b/src/main/java/net/minecraft/server/LegacyPingHandler.java
index f084a653a..39d19e91b 100644
index a89a86e6d..2762bcc2e 100644
--- a/src/main/java/net/minecraft/server/LegacyPingHandler.java
+++ b/src/main/java/net/minecraft/server/LegacyPingHandler.java
@@ -9,6 +9,7 @@ import java.net.InetSocketAddress;
@ -133,7 +133,7 @@ index f084a653a..39d19e91b 100644
this.a(channelhandlercontext, this.a(s));
break;
@@ -161,8 +178,16 @@ public class LegacyPingHandler extends ChannelInboundHandlerAdapter {
@@ -169,8 +186,16 @@ public class LegacyPingHandler extends ChannelInboundHandlerAdapter {
a.debug("Ping: (1.6) from {}", ctx.channel().remoteAddress());