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Code Issues Releases Wiki Activity

Sort compounds in NBT lists for hashing (#1391)

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Drew Edwards 2023-03-26 17:49:52 +01:00 committed by GitHub
parent 82947a6e67
commit 0046b095b1
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2 changed files with 135 additions and 5 deletions
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21
projects/common/src/main/java/dan200/computercraft/shared/util/NBTUtil.java
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@ -4,6 +4,7 @@
package dan200.computercraft.shared.util;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.io.BaseEncoding;
import dan200.computercraft.core.util.Nullability;
import net.minecraft.nbt.*;
@ -23,7 +24,8 @@
public final class NBTUtil {
private static final Logger LOG = LoggerFactory.getLogger(NBTUtil.class);
private static final BaseEncoding ENCODING = BaseEncoding.base16().lowerCase();
@VisibleForTesting
static final BaseEncoding ENCODING = BaseEncoding.base16().lowerCase();
private NBTUtil() {
}
@ -156,7 +158,7 @@ public static String getNBTHash(@Nullable CompoundTag tag) {
try {
var digest = MessageDigest.getInstance("MD5");
DataOutput output = new DataOutputStream(new DigestOutputStream(digest));
writeTag(output, "", tag);
writeNamedTag(output, "", tag);
var hash = digest.digest();
return ENCODING.encode(hash);
} catch (NoSuchAlgorithmException | IOException e) {
@ -175,24 +177,33 @@ public static String getNBTHash(@Nullable CompoundTag tag) {
* @throws IOException If the underlying stream throws.
* @see NbtIo#write(CompoundTag, DataOutput)
* @see CompoundTag#write(DataOutput)
* @see ListTag#write(DataOutput)
*/
private static void writeTag(DataOutput output, String name, Tag tag) throws IOException {
private static void writeNamedTag(DataOutput output, String name, Tag tag) throws IOException {
output.writeByte(tag.getId());
if (tag.getId() == 0) return;
output.writeUTF(name);
writeTag(output, tag);
}
private static void writeTag(DataOutput output, Tag tag) throws IOException {
if (tag instanceof CompoundTag compound) {
var keys = compound.getAllKeys().toArray(new String[0]);
Arrays.sort(keys);
for (var key : keys) writeTag(output, key, Nullability.assertNonNull(compound.get(key)));
for (var key : keys) writeNamedTag(output, key, Nullability.assertNonNull(compound.get(key)));
output.writeByte(0);
} else if (tag instanceof ListTag list) {
output.writeByte(list.isEmpty() ? 0 : list.get(0).getId());
output.writeInt(list.size());
for (var value : list) writeTag(output, value);
} else {
tag.write(output);
}
}
private static final class DigestOutputStream extends OutputStream {
@VisibleForTesting
static final class DigestOutputStream extends OutputStream {
private final MessageDigest digest;
DigestOutputStream(MessageDigest digest) {

119
projects/common/src/test/java/dan200/computercraft/shared/util/NBTUtilTest.java Normal file
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@ -0,0 +1,119 @@
// SPDX-FileCopyrightText: 2022 The CC: Tweaked Developers
//
// SPDX-License-Identifier: MPL-2.0
package dan200.computercraft.shared.util;
import dan200.computercraft.test.shared.WithMinecraft;
import net.minecraft.Util;
import net.minecraft.nbt.CompoundTag;
import net.minecraft.nbt.ListTag;
import net.minecraft.nbt.NbtIo;
import org.junit.jupiter.api.Test;
import java.io.DataOutput;
import java.io.DataOutputStream;
import java.io.File;
import java.io.IOException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.List;
import static dan200.computercraft.shared.util.NBTUtil.getNBTHash;
import static org.junit.jupiter.api.Assertions.*;
@WithMinecraft
public class NBTUtilTest {
@Test
public void testCompoundTagSorting() {
var nbt1 = makeCompoundTag(false);
var hash1 = getNBTHash(nbt1);
var nbt2 = makeCompoundTag(true);
var hash2 = getNBTHash(nbt2);
assertNotNull(hash1, "NBT hash should not be null");
assertNotNull(hash2, "NBT hash should not be null");
assertEquals(hash1, hash2, "NBT hashes should be equal");
}
@Test
public void testListTagSorting() {
var nbt1 = new CompoundTag();
nbt1.put("Items", makeListTag(false));
var hash1 = getNBTHash(nbt1);
var nbt2 = new CompoundTag();
nbt2.put("Items", makeListTag(true));
var hash2 = getNBTHash(nbt2);
assertNotNull(hash1, "NBT hash should not be null");
assertNotNull(hash2, "NBT hash should not be null");
assertEquals(hash1, hash2, "NBT hashes should be equal");
}
@Test
public void testTagsHaveDifferentOrders() {
var nbt1 = makeCompoundTag(false);
var nbt2 = makeCompoundTag(true);
assertNotEquals(
List.copyOf(nbt1.getAllKeys()), List.copyOf(nbt2.getAllKeys()),
"Expected makeCompoundTag to return keys with different orders."
);
}
@Test
public void testHashEquivalentForBasicValues() {
var nbt = new CompoundTag();
nbt.put("list", Util.make(new ListTag(), list -> {
list.add(Util.make(new CompoundTag(), t -> t.putBoolean("key", true)));
list.add(Util.make(new CompoundTag(), t -> t.putInt("key", 23)));
}));
assertEquals(getNBTHash(nbt), getNBTHashDefault(nbt));
}
private static CompoundTag makeCompoundTag(boolean grow) {
var nbt = new CompoundTag();
nbt.putString("Slot", "Slot 1");
nbt.putString("Count", "64");
nbt.putString("id", "123");
// Grow the map to cause a rehash and (hopefully) change the order around a little bit.
if (grow) {
for (var i = 0; i < 64; i++) nbt.putBoolean("x" + i, true);
for (var i = 0; i < 64; i++) nbt.remove("x" + i);
}
return nbt;
}
private static ListTag makeListTag(boolean reverse) {
var list = new ListTag();
for (var i = 0; i < 3; i++) {
list.add(makeCompoundTag(reverse));
}
return list;
}
/**
* Equivalent to {@link NBTUtil#getNBTHash(CompoundTag)}, but using the default {@link NbtIo#write(CompoundTag, File)} method.
*
* @param tag The tag to hash.
* @return The resulting hash.
*/
private static String getNBTHashDefault(CompoundTag tag) {
try {
var digest = MessageDigest.getInstance("MD5");
DataOutput output = new DataOutputStream(new NBTUtil.DigestOutputStream(digest));
NbtIo.write(tag, output);
var hash = digest.digest();
return NBTUtil.ENCODING.encode(hash);
} catch (NoSuchAlgorithmException | IOException e) {
throw new IllegalStateException(e);
}
}
}