Configurable damage tick when blocking with shield (#10877)

A long standing bug in spigot and its derivatives was the fact that
players taking damage while blocking with a shield would not receive
invulnerability, while they do in vanilla.

This enabled the pvp technique of disabling a shield and immediately
attacking again to knock a player into the air.
While upstream fixed this and properly aligned itself with vanilla
damage logic (in this specific case) changing such long standing
behaviour has some downsides.

To allow players used to this specific bug to still use it, this patch
introduces a configuration option to re-introduce said bug.
As there is no easy way to *only* re-add this bug, the option is found
in the unsupported section as it may introduce other damage related
disparity from vanilla.

1 files changed, 375 insertions, 0 deletions

diff --git a/patches/server/1006-Use-Velocity-compression-and-cipher-natives.patch b/patches/server/1006-Use-Velocity-compression-and-cipher-natives.patch
new file mode 100644
index 0000000000..fd68f70524
--- /dev/null
+++ b/patches/server/1006-Use-Velocity-compression-and-cipher-natives.patch
@@ -0,0 +1,375 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Andrew Steinborn <[email protected]>
+Date: Mon, 26 Jul 2021 02:15:17 -0400
+Subject: [PATCH] Use Velocity compression and cipher natives
+
+
+diff --git a/build.gradle.kts b/build.gradle.kts
+index b06f38b87765d084565bc11cf5da6076562b6be8..299b7b029384c58fed80d53cc0b77c420d62eed7 100644
+--- a/build.gradle.kts
++++ b/build.gradle.kts
+@@ -37,6 +37,11 @@ dependencies {
+     runtimeOnly("org.xerial:sqlite-jdbc:3.46.0.0")
+     runtimeOnly("com.mysql:mysql-connector-j:8.4.0")
+     runtimeOnly("com.lmax:disruptor:3.4.4") // Paper
++    // Paper start - Use Velocity cipher
++    implementation("com.velocitypowered:velocity-native:3.1.2-SNAPSHOT") {
++        isTransitive = false
++    }
++    // Paper end - Use Velocity cipher
+ 
+     runtimeOnly("org.apache.maven:maven-resolver-provider:3.9.6")
+     runtimeOnly("org.apache.maven.resolver:maven-resolver-connector-basic:1.9.18")
+diff --git a/src/main/java/net/minecraft/network/CipherDecoder.java b/src/main/java/net/minecraft/network/CipherDecoder.java
+index 778beb445eac5769b9e4e07b4d1294c50ae2602b..7b895b6a626da6297f07582e96d98ecfb6c8c951 100644
+--- a/src/main/java/net/minecraft/network/CipherDecoder.java
++++ b/src/main/java/net/minecraft/network/CipherDecoder.java
+@@ -7,13 +7,29 @@ import java.util.List;
+ import javax.crypto.Cipher;
+ 
+ public class CipherDecoder extends MessageToMessageDecoder<ByteBuf> {
+-    private final CipherBase cipher;
++    private final com.velocitypowered.natives.encryption.VelocityCipher cipher; // Paper - Use Velocity cipher
+ 
+-    public CipherDecoder(Cipher cipher) {
+-        this.cipher = new CipherBase(cipher);
++    public CipherDecoder(com.velocitypowered.natives.encryption.VelocityCipher cipher) {  // Paper - Use Velocity cipher
++        this.cipher = cipher;  // Paper - Use Velocity cipher
+     }
+ 
+     protected void decode(ChannelHandlerContext channelHandlerContext, ByteBuf byteBuf, List<Object> list) throws Exception {
+-        list.add(this.cipher.decipher(channelHandlerContext, byteBuf));
++        // Paper start - Use Velocity cipher
++        ByteBuf compatible = com.velocitypowered.natives.util.MoreByteBufUtils.ensureCompatible(channelHandlerContext.alloc(), cipher, byteBuf);
++        try {
++            cipher.process(compatible);
++            list.add(compatible);
++        } catch (Exception e) {
++            compatible.release(); // compatible will never be used if we throw an exception
++            throw e;
++        }
++        // Paper end - Use Velocity cipher
+     }
++
++    // Paper start - Use Velocity cipher
++    @Override
++    public void handlerRemoved(ChannelHandlerContext ctx) throws Exception {
++        cipher.close();
++    }
++    // Paper end - Use Velocity cipher
+ }
+diff --git a/src/main/java/net/minecraft/network/CipherEncoder.java b/src/main/java/net/minecraft/network/CipherEncoder.java
+index 0f3d502a9680006bcdcd7d272240a2e5c3b46790..ffa1c48585fbbc1d30826d435043527f6183a3ee 100644
+--- a/src/main/java/net/minecraft/network/CipherEncoder.java
++++ b/src/main/java/net/minecraft/network/CipherEncoder.java
+@@ -4,15 +4,32 @@ import io.netty.buffer.ByteBuf;
+ import io.netty.channel.ChannelHandlerContext;
+ import io.netty.handler.codec.MessageToByteEncoder;
+ import javax.crypto.Cipher;
++import java.util.List;
+ 
+-public class CipherEncoder extends MessageToByteEncoder<ByteBuf> {
+-    private final CipherBase cipher;
++public class CipherEncoder extends io.netty.handler.codec.MessageToMessageEncoder<ByteBuf> { // Paper - Use Velocity cipher; change superclass
++    private final com.velocitypowered.natives.encryption.VelocityCipher cipher; // Paper - Use Velocity cipher
+ 
+-    public CipherEncoder(Cipher cipher) {
+-        this.cipher = new CipherBase(cipher);
++    public CipherEncoder(com.velocitypowered.natives.encryption.VelocityCipher cipher) {  // Paper - Use Velocity cipher
++        this.cipher = cipher;  // Paper - Use Velocity cipher
+     }
+ 
+-    protected void encode(ChannelHandlerContext channelHandlerContext, ByteBuf byteBuf, ByteBuf byteBuf2) throws Exception {
+-        this.cipher.encipher(byteBuf, byteBuf2);
++    protected void encode(ChannelHandlerContext channelHandlerContext, ByteBuf byteBuf, List<Object> list) throws Exception {
++        // Paper start - Use Velocity cipher
++        ByteBuf compatible = com.velocitypowered.natives.util.MoreByteBufUtils.ensureCompatible(channelHandlerContext.alloc(), cipher, byteBuf);
++        try {
++            cipher.process(compatible);
++            list.add(compatible);
++        } catch (Exception e) {
++            compatible.release(); // compatible will never be used if we throw an exception
++            throw e;
++        }
++        // Paper end - Use Velocity cipher
+     }
++
++    // Paper start - Use Velocity cipher
++    @Override
++    public void handlerRemoved(ChannelHandlerContext ctx) throws Exception {
++        cipher.close();
++    }
++    // Paper end - Use Velocity cipher
+ }
+diff --git a/src/main/java/net/minecraft/network/CompressionDecoder.java b/src/main/java/net/minecraft/network/CompressionDecoder.java
+index 5927c928b27f64bd3973e95d5867b59f67476d41..ba3619b03ea73e4ea55ae2eb79d3b6cd1f48a191 100644
+--- a/src/main/java/net/minecraft/network/CompressionDecoder.java
++++ b/src/main/java/net/minecraft/network/CompressionDecoder.java
+@@ -13,13 +13,20 @@ public class CompressionDecoder extends ByteToMessageDecoder {
+     public static final int MAXIMUM_COMPRESSED_LENGTH = 2097152;
+     public static final int MAXIMUM_UNCOMPRESSED_LENGTH = 8388608;
+     private final Inflater inflater;
++    private com.velocitypowered.natives.compression.VelocityCompressor compressor; // Paper - Use Velocity cipher
+     private int threshold;
+     private boolean validateDecompressed;
+ 
++    // Paper start - Use Velocity cipher
+     public CompressionDecoder(int compressionThreshold, boolean rejectsBadPackets) {
++        this(null, compressionThreshold, rejectsBadPackets);
++    }
++    public CompressionDecoder(com.velocitypowered.natives.compression.VelocityCompressor compressor, int compressionThreshold, boolean rejectsBadPackets) {
+         this.threshold = compressionThreshold;
+         this.validateDecompressed = rejectsBadPackets;
+-        this.inflater = new Inflater();
++        this.inflater = compressor == null ? new Inflater() : null;
++        this.compressor = compressor;
++        // Paper end - Use Velocity cipher
+     }
+ 
+     protected void decode(ChannelHandlerContext channelHandlerContext, ByteBuf byteBuf, List<Object> list) throws Exception {
+@@ -38,14 +45,42 @@ public class CompressionDecoder extends ByteToMessageDecoder {
+                     }
+                 }
+ 
++                if (inflater != null) { // Paper - Use Velocity cipher; fallback to vanilla inflater
+                 this.setupInflaterInput(byteBuf);
+                 ByteBuf byteBuf2 = this.inflate(channelHandlerContext, i);
+                 this.inflater.reset();
+                 list.add(byteBuf2);
++                return; // Paper - Use Velocity cipher
++                } // Paper - use velocity compression
++
++                // Paper start - Use Velocity cipher
++                int claimedUncompressedSize = i; // OBFHELPER
++                ByteBuf compatibleIn = com.velocitypowered.natives.util.MoreByteBufUtils.ensureCompatible(channelHandlerContext.alloc(), this.compressor, byteBuf);
++                ByteBuf uncompressed = com.velocitypowered.natives.util.MoreByteBufUtils.preferredBuffer(channelHandlerContext.alloc(), this.compressor, claimedUncompressedSize);
++                try {
++                    this.compressor.inflate(compatibleIn, uncompressed, claimedUncompressedSize);
++                    list.add(uncompressed);
++                    byteBuf.clear();
++                } catch (Exception e) {
++                    uncompressed.release();
++                    throw e;
++                } finally {
++                    compatibleIn.release();
++                }
++                // Paper end - Use Velocity cipher
+             }
+         }
+     }
+ 
++    // Paper start - Use Velocity cipher
++    @Override
++    public void handlerRemoved0(ChannelHandlerContext ctx) throws Exception {
++        if (this.compressor != null) {
++            this.compressor.close();
++        }
++    }
++    // Paper end - Use Velocity cipher
++
+     private void setupInflaterInput(ByteBuf buf) {
+         ByteBuffer byteBuffer;
+         if (buf.nioBufferCount() > 0) {
+@@ -82,7 +117,7 @@ public class CompressionDecoder extends ByteToMessageDecoder {
+         }
+     }
+ 
+-    public void setThreshold(int compressionThreshold, boolean rejectsBadPackets) {
++    public void setThreshold(com.velocitypowered.natives.compression.VelocityCompressor compressor, int compressionThreshold, boolean rejectsBadPackets) { // Paper - Use Velocity cipher
+         this.threshold = compressionThreshold;
+         this.validateDecompressed = rejectsBadPackets;
+     }
+diff --git a/src/main/java/net/minecraft/network/CompressionEncoder.java b/src/main/java/net/minecraft/network/CompressionEncoder.java
+index 34a80d2f34555663ab1b394972957089214cb337..ec30c291188ac3bba7f1c3bc397576d1edb0a57f 100644
+--- a/src/main/java/net/minecraft/network/CompressionEncoder.java
++++ b/src/main/java/net/minecraft/network/CompressionEncoder.java
+@@ -6,16 +6,31 @@ import io.netty.handler.codec.MessageToByteEncoder;
+ import java.util.zip.Deflater;
+ 
+ public class CompressionEncoder extends MessageToByteEncoder<ByteBuf> {
+-    private final byte[] encodeBuf = new byte[8192];
++    @javax.annotation.Nullable private final byte[] encodeBuf; // Paper - Use Velocity cipher
++    @javax.annotation.Nullable // Paper - Use Velocity cipher
+     private final Deflater deflater;
++    @javax.annotation.Nullable // Paper - Use Velocity cipher
++    private final com.velocitypowered.natives.compression.VelocityCompressor compressor; // Paper - Use Velocity cipher
+     private int threshold;
+ 
++    // Paper start - Use Velocity cipher
+     public CompressionEncoder(int compressionThreshold) {
++        this(null, compressionThreshold);
++    }
++    public CompressionEncoder(@javax.annotation.Nullable com.velocitypowered.natives.compression.VelocityCompressor compressor, int compressionThreshold) {
+         this.threshold = compressionThreshold;
+-        this.deflater = new Deflater();
++        if (compressor == null) {
++            this.encodeBuf = new byte[8192];
++            this.deflater = new Deflater();
++        } else {
++            this.encodeBuf = null;
++            this.deflater = null;
++        }
++        this.compressor = compressor;
++        // Paper end - Use Velocity cipher
+     }
+ 
+-    protected void encode(ChannelHandlerContext channelHandlerContext, ByteBuf byteBuf, ByteBuf byteBuf2) {
++    protected void encode(ChannelHandlerContext channelHandlerContext, ByteBuf byteBuf, ByteBuf byteBuf2) throws Exception { // Paper - Use Velocity cipher
+         int i = byteBuf.readableBytes();
+         if (i > 8388608) {
+             throw new IllegalArgumentException("Packet too big (is " + i + ", should be less than 8388608)");
+@@ -24,6 +39,7 @@ public class CompressionEncoder extends MessageToByteEncoder<ByteBuf> {
+                 VarInt.write(byteBuf2, 0);
+                 byteBuf2.writeBytes(byteBuf);
+             } else {
++                if (this.deflater != null) { // Paper - Use Velocity cipher
+                 byte[] bs = new byte[i];
+                 byteBuf.readBytes(bs);
+                 VarInt.write(byteBuf2, bs.length);
+@@ -36,10 +52,47 @@ public class CompressionEncoder extends MessageToByteEncoder<ByteBuf> {
+                 }
+ 
+                 this.deflater.reset();
++                // Paper start - Use Velocity cipher
++                    return;
++                }
++
++                VarInt.write(byteBuf2, i);
++                final ByteBuf compatibleIn = com.velocitypowered.natives.util.MoreByteBufUtils.ensureCompatible(channelHandlerContext.alloc(), this.compressor, byteBuf);
++                try {
++                    this.compressor.deflate(compatibleIn, byteBuf2);
++                } finally {
++                    compatibleIn.release();
++                }
+             }
+         }
+     }
+ 
++    @Override
++    protected ByteBuf allocateBuffer(ChannelHandlerContext ctx, ByteBuf msg, boolean preferDirect) throws Exception{
++        if (this.compressor != null) {
++            // We allocate bytes to be compressed plus 1 byte. This covers two cases:
++            //
++            // - Compression
++            //    According to https://github.com/ebiggers/libdeflate/blob/master/libdeflate.h#L103,
++            //    if the data compresses well (and we do not have some pathological case) then the maximum
++            //    size the compressed size will ever be is the input size minus one.
++            // - Uncompressed
++            //    This is fairly obvious - we will then have one more than the uncompressed size.
++            final int initialBufferSize = msg.readableBytes() + 1;
++            return com.velocitypowered.natives.util.MoreByteBufUtils.preferredBuffer(ctx.alloc(), this.compressor, initialBufferSize);
++        }
++
++        return super.allocateBuffer(ctx, msg, preferDirect);
++    }
++
++    @Override
++    public void handlerRemoved(ChannelHandlerContext ctx) throws Exception {
++        if (this.compressor != null) {
++            this.compressor.close();
++            // Paper end - Use Velocity cipher
++        }
++    }
++
+     public int getThreshold() {
+         return this.threshold;
+     }
+diff --git a/src/main/java/net/minecraft/network/Connection.java b/src/main/java/net/minecraft/network/Connection.java
+index 7dc7aeb1d94d26cf54bd4e4ab13972a3a60c1f98..90a2c61c42cba7e38f167eccdd7a951a947963c4 100644
+--- a/src/main/java/net/minecraft/network/Connection.java
++++ b/src/main/java/net/minecraft/network/Connection.java
+@@ -792,11 +792,28 @@ public class Connection extends SimpleChannelInboundHandler<Packet<?>> {
+         return networkmanager;
+     }
+ 
+-    public void setEncryptionKey(Cipher decryptionCipher, Cipher encryptionCipher) {
+-        this.encrypted = true;
+-        this.channel.pipeline().addBefore("splitter", "decrypt", new CipherDecoder(decryptionCipher));
+-        this.channel.pipeline().addBefore("prepender", "encrypt", new CipherEncoder(encryptionCipher));
++    // Paper start - Use Velocity cipher
++//    public void setEncryptionKey(Cipher decryptionCipher, Cipher encryptionCipher) {
++//        this.encrypted = true;
++//        this.channel.pipeline().addBefore("splitter", "decrypt", new CipherDecoder(decryptionCipher));
++//        this.channel.pipeline().addBefore("prepender", "encrypt", new CipherEncoder(encryptionCipher));
++//    }
++
++    public void setupEncryption(javax.crypto.SecretKey key) throws net.minecraft.util.CryptException {
++        if (!this.encrypted) {
++            try {
++                com.velocitypowered.natives.encryption.VelocityCipher decryption = com.velocitypowered.natives.util.Natives.cipher.get().forDecryption(key);
++                com.velocitypowered.natives.encryption.VelocityCipher encryption = com.velocitypowered.natives.util.Natives.cipher.get().forEncryption(key);
++
++                this.encrypted = true;
++                this.channel.pipeline().addBefore("splitter", "decrypt", new CipherDecoder(decryption));
++                this.channel.pipeline().addBefore("prepender", "encrypt", new CipherEncoder(encryption));
++            } catch (java.security.GeneralSecurityException e) {
++                throw new net.minecraft.util.CryptException(e);
++            }
++        }
+     }
++    // Paper end - Use Velocity cipher
+ 
+     public boolean isEncrypted() {
+         return this.encrypted;
+@@ -829,12 +846,13 @@ public class Connection extends SimpleChannelInboundHandler<Packet<?>> {
+ 
+     public void setupCompression(int compressionThreshold, boolean rejectsBadPackets) {
+         if (compressionThreshold >= 0) {
++            com.velocitypowered.natives.compression.VelocityCompressor compressor = com.velocitypowered.natives.util.Natives.compress.get().create(io.papermc.paper.configuration.GlobalConfiguration.get().misc.compressionLevel.or(-1)); // Paper - Use Velocity cipher
+             ChannelHandler channelhandler = this.channel.pipeline().get("decompress");
+ 
+             if (channelhandler instanceof CompressionDecoder) {
+                 CompressionDecoder packetdecompressor = (CompressionDecoder) channelhandler;
+ 
+-                packetdecompressor.setThreshold(compressionThreshold, rejectsBadPackets);
++                packetdecompressor.setThreshold(compressor, compressionThreshold, rejectsBadPackets); // Paper - Use Velocity cipher
+             } else {
+                 this.channel.pipeline().addAfter("splitter", "decompress", new CompressionDecoder(compressionThreshold, rejectsBadPackets));
+             }
+@@ -845,7 +863,7 @@ public class Connection extends SimpleChannelInboundHandler<Packet<?>> {
+ 
+                 packetcompressor.setThreshold(compressionThreshold);
+             } else {
+-                this.channel.pipeline().addAfter("prepender", "compress", new CompressionEncoder(compressionThreshold));
++                this.channel.pipeline().addAfter("prepender", "compress", new CompressionEncoder(compressor, compressionThreshold)); // Paper - Use Velocity cipher
+             }
+             this.channel.pipeline().fireUserEventTriggered(io.papermc.paper.network.ConnectionEvent.COMPRESSION_THRESHOLD_SET); // Paper - Add Channel initialization listeners
+         } else {
+diff --git a/src/main/java/net/minecraft/server/network/ServerConnectionListener.java b/src/main/java/net/minecraft/server/network/ServerConnectionListener.java
+index 2929d9a2efa9669781b6773161db7c5f968c2544..8aff5129f85ab5729b3da2e465871be62d15bdf2 100644
+--- a/src/main/java/net/minecraft/server/network/ServerConnectionListener.java
++++ b/src/main/java/net/minecraft/server/network/ServerConnectionListener.java
+@@ -106,6 +106,11 @@ public class ServerConnectionListener {
+                 ServerConnectionListener.LOGGER.info("Using default channel type");
+             }
+ 
++            // Paper start - Use Velocity cipher
++            ServerConnectionListener.LOGGER.info("Paper: Using " + com.velocitypowered.natives.util.Natives.compress.getLoadedVariant() + " compression from Velocity.");
++            ServerConnectionListener.LOGGER.info("Paper: Using " + com.velocitypowered.natives.util.Natives.cipher.getLoadedVariant() + " cipher from Velocity.");
++            // Paper end - Use Velocity cipher
++
+             this.channels.add(((ServerBootstrap) ((ServerBootstrap) (new ServerBootstrap()).channel(oclass)).childHandler(new ChannelInitializer<Channel>() {
+                 protected void initChannel(Channel channel) {
+                     try {
+diff --git a/src/main/java/net/minecraft/server/network/ServerLoginPacketListenerImpl.java b/src/main/java/net/minecraft/server/network/ServerLoginPacketListenerImpl.java
+index 0fc30ce511f449d2a3ddab28c86f7e388223ece1..b0f7a378f19b9837c060c891002cd5db756cdae1 100644
+--- a/src/main/java/net/minecraft/server/network/ServerLoginPacketListenerImpl.java
++++ b/src/main/java/net/minecraft/server/network/ServerLoginPacketListenerImpl.java
+@@ -282,12 +282,14 @@ public class ServerLoginPacketListenerImpl implements ServerLoginPacketListener,
+             }
+ 
+             SecretKey secretkey = packet.getSecretKey(privatekey);
+-            Cipher cipher = Crypt.getCipher(2, secretkey);
+-            Cipher cipher1 = Crypt.getCipher(1, secretkey);
++            // Paper start - Use Velocity cipher
++//            Cipher cipher = Crypt.getCipher(2, secretkey);
++//            Cipher cipher1 = Crypt.getCipher(1, secretkey);
++            // Paper end - Use Velocity cipher
+ 
+             s = (new BigInteger(Crypt.digestData("", this.server.getKeyPair().getPublic(), secretkey))).toString(16);
+             this.state = ServerLoginPacketListenerImpl.State.AUTHENTICATING;
+-            this.connection.setEncryptionKey(cipher, cipher1);
++            this.connection.setupEncryption(secretkey); // Paper - Use Velocity cipher
+         } catch (CryptException cryptographyexception) {
+             throw new IllegalStateException("Protocol error", cryptographyexception);
+         }