From 7fbb26092fd3a619a131ec1f60d25dee136f6cef Mon Sep 17 00:00:00 2001
From: sasheg dev <152582704+SashegDev@users.noreply.github.com>
Date: Mon, 19 Oct 2026 01:10:26 +0300
Subject: [PATCH] =?UTF-8?q?=D0=9A=D0=B0=D1=80=D0=BA=D0=B0=D1=81=20=D0=BF?=
=?UTF-8?q?=D1=80=D0=BE=D1=82=D0=BE=D0=BA=D0=BE=D0=BB=D0=B0:=20=D0=BA?=
=?UTF-8?q?=D0=B0=D0=B4=D1=80=D0=B8=D1=80=D0=BE=D0=B2=D0=B0=D0=BD=D0=B8?=
=?UTF-8?q?=D0=B5,=20=D0=B1=D1=83=D1=84=D0=B5=D1=80=20=D0=B8=20=D1=80?=
=?UTF-8?q?=D1=83=D0=BA=D0=BE=D0=BF=D0=BE=D0=B6=D0=B0=D1=82=D0=B8=D0=B5?=
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Это первый настоящий кусок сервера. Пока он ничего не умеет, кроме того что
умеет правильно: принимать байты от чужого человека и не дать ему ничего
сделать с нами.
Формат кадра — четыре байта магии RSX1, версия, id пакета, длина тела и
само тело. Магия стоит в начале, чтобы порт мог сразу ответить, а не ждать
объяснений.
Главное здесь — границы. Сервер живёт тем, что вынимает числа из сокетов
чужих людей, и разница между дешёвой проверкой и аллокацией — это разница
между «противник стоил нам пары тактов» и «противник стоил нам кучи».
- Длина тела проверяется до того, как под неё что-то зарезервировано.
Единственное, на что полезна вредная длина, — заставить сервер выделить
память.
- Varint ограничен пятью байтами для int и десятью для long. Без этого
десять байт 0xFF превращают пятибайтовое целое в бесконечный цикл.
- Длина строки ограничена до того, как под неё читают байты.
- Декодер держит не больше одного максимального кадра плюс неполный
заголовок.
Неполные данные и испорченные — это разные вещи, и раньше это не было
разделено: конверт, разрезанный сетью посреди varint, выглядел как
испорченный и рвал соединение. IncompleteException означает «остальное
уже в пути», ProtocolException — «потока больше не будет». TCP режет кадры
почти всегда, так что первое поведение было бы отказом от большинства
соединений.
Позиция упакована одним varint, но доли у осей не равные: три поля по 26 бит
это 78 бит, они не влезают в 64. X и Z получают по 26 бит с шагом 1/32
блока, Y — оставшиеся 12 бит целыми блоками. Со смещением на 2048 не
вышло бы: для диапазона 0..4095 нужен тринадцатый бит, и это ровно тот бит,
по которому значение читается обратно отрицательным.
Первый прогон тестов нашёл все три ошибки сразу, две из них — в упаковке
позиции. Проверено 17 сценариев, включая «по одному байту», пятьдесят
кадров за одно чтение, чужую магию и объявленное тело в два гигабайта.
Собирается и тестируется одним JDK, без Gradle и без сети, как и всё
остальное в проекте.
---
rsx-protocol/scripts/build.ps1 | 63 +++
rsx-protocol/scripts/test.ps1 | 42 ++
.../main/java/net/rustnotmc/protocol/Buf.java | 343 +++++++++++++++
.../java/net/rustnotmc/protocol/Frame.java | 144 +++++++
.../net/rustnotmc/protocol/FrameDecoder.java | 124 ++++++
.../protocol/IncompleteException.java | 19 +
.../java/net/rustnotmc/protocol/Packets.java | 266 ++++++++++++
.../rustnotmc/protocol/ProtocolException.java | 21 +
.../net/rustnotmc/protocol/ProtocolTest.java | 407 ++++++++++++++++++
9 files changed, 1429 insertions(+)
create mode 100644 rsx-protocol/scripts/build.ps1
create mode 100644 rsx-protocol/scripts/test.ps1
create mode 100644 rsx-protocol/src/main/java/net/rustnotmc/protocol/Buf.java
create mode 100644 rsx-protocol/src/main/java/net/rustnotmc/protocol/Frame.java
create mode 100644 rsx-protocol/src/main/java/net/rustnotmc/protocol/FrameDecoder.java
create mode 100644 rsx-protocol/src/main/java/net/rustnotmc/protocol/IncompleteException.java
create mode 100644 rsx-protocol/src/main/java/net/rustnotmc/protocol/Packets.java
create mode 100644 rsx-protocol/src/main/java/net/rustnotmc/protocol/ProtocolException.java
create mode 100644 rsx-protocol/src/test/java/net/rustnotmc/protocol/ProtocolTest.java
diff --git a/rsx-protocol/scripts/build.ps1 b/rsx-protocol/scripts/build.ps1
new file mode 100644
index 0000000..c34f6d7
--- /dev/null
+++ b/rsx-protocol/scripts/build.ps1
@@ -0,0 +1,63 @@
+# Builds rsx-protocol into dist\.
+#
+# Only a JDK is required, same as the loader: javac with --release 17, no Gradle
+# and no network. The protocol is deliberately dependency free so both ends can
+# carry it and so its tests run without a game, a server or a socket library.
+#
+# NOTE: ASCII on purpose. Windows PowerShell 5.1 reads a .ps1 with no byte order
+# mark using the system ANSI code page, which mangles UTF-8 and breaks the
+# parser. Keep script messages English.
+
+$ErrorActionPreference = 'Stop'
+
+$Repo = Split-Path -Parent $PSScriptRoot
+if (-not $Repo) { $Repo = $PSCommandPath | Split-Path -Parent | Split-Path -Parent }
+$Dist = Join-Path $Repo 'dist'
+$Out = Join-Path $Repo 'build'
+
+function Say($text) { Write-Host " $text" -ForegroundColor Cyan }
+
+if (-not (Get-Command javac -ErrorAction SilentlyContinue)) {
+ Write-Host ' A JDK (javac) is required.' -ForegroundColor Red
+ exit 1
+}
+
+New-Item -ItemType Directory -Force -Path $Dist, $Out | Out-Null
+
+$mainOut = Join-Path $Out 'classes'
+Remove-Item $mainOut -Recurse -Force -ErrorAction SilentlyContinue
+New-Item -ItemType Directory -Force -Path $mainOut | Out-Null
+
+$mainFiles = @(Get-ChildItem (Join-Path $Repo 'src\main\java') -Recurse -Filter '*.java' |
+ ForEach-Object { $_.FullName })
+if ($mainFiles.Count -eq 0) {
+ Write-Host ' No sources found.' -ForegroundColor Red
+ exit 1
+}
+
+& javac -encoding UTF-8 --release 17 -Xlint:-options -nowarn -d $mainOut $mainFiles
+if ($LASTEXITCODE -ne 0) {
+ Write-Host ' Protocol failed to compile.' -ForegroundColor Red
+ exit 1
+}
+Say "protocol compiled ($($mainFiles.Count) files)"
+
+$manifest = Join-Path $Out 'manifest.txt'
+@"
+Manifest-Version: 1.0
+Implementation-Title: RustNotMC protocol
+Implementation-Version: 0.1.0
+"@ | Set-Content -LiteralPath $manifest -Encoding ASCII
+
+$jar = Join-Path $Dist 'rsx-protocol.jar'
+if (Test-Path -LiteralPath $jar) { Remove-Item -LiteralPath $jar -Force }
+& jar cfm $jar $manifest -C $mainOut .
+if ($LASTEXITCODE -ne 0) {
+ Write-Host ' Could not package the jar.' -ForegroundColor Red
+ exit 1
+}
+Say "rsx-protocol.jar ($((Get-Item $jar).Length) bytes)"
+
+Write-Host ''
+Write-Host ' Done:' -ForegroundColor Green
+Write-Host " $jar"
\ No newline at end of file
diff --git a/rsx-protocol/scripts/test.ps1 b/rsx-protocol/scripts/test.ps1
new file mode 100644
index 0000000..eb01e50
--- /dev/null
+++ b/rsx-protocol/scripts/test.ps1
@@ -0,0 +1,42 @@
+# Compiles rsx-protocol plus its tests and runs them.
+#
+# ASCII only, for the same reason as build.ps1.
+
+$ErrorActionPreference = 'Stop'
+
+$Repo = Split-Path -Parent $PSScriptRoot
+if (-not $Repo) { $Repo = $PSCommandPath | Split-Path -Parent | Split-Path -Parent }
+$Out = Join-Path $Repo 'build'
+
+function Say($text) { Write-Host " $text" -ForegroundColor Cyan }
+
+New-Item -ItemType Directory -Force -Path $Out | Out-Null
+
+$mainOut = Join-Path $Out 'classes'
+Remove-Item $mainOut -Recurse -Force -ErrorAction SilentlyContinue
+New-Item -ItemType Directory -Force -Path $mainOut | Out-Null
+
+$mainFiles = @(Get-ChildItem (Join-Path $Repo 'src\main\java') -Recurse -Filter '*.java' |
+ ForEach-Object { $_.FullName })
+& javac -encoding UTF-8 --release 17 -Xlint:-options -nowarn -d $mainOut $mainFiles
+if ($LASTEXITCODE -ne 0) { Write-Host ' Main failed.' -ForegroundColor Red; exit 1 }
+
+$testOut = Join-Path $Out 'test-classes'
+Remove-Item $testOut -Recurse -Force -ErrorAction SilentlyContinue
+New-Item -ItemType Directory -Force -Path $testOut | Out-Null
+
+$testFiles = @(Get-ChildItem (Join-Path $Repo 'src\test\java') -Recurse -Filter '*.java' |
+ ForEach-Object { $_.FullName })
+& javac -encoding UTF-8 --release 17 -Xlint:-options -nowarn -cp $mainOut -d $testOut $testFiles
+if ($LASTEXITCODE -ne 0) { Write-Host ' Test failed to compile.' -ForegroundColor Red; exit 1 }
+Say "compiled $($mainFiles.Count) main + $($testFiles.Count) test files"
+
+& java -cp "$mainOut;$testOut" net.rustnotmc.protocol.ProtocolTest
+if ($LASTEXITCODE -ne 0) {
+ Write-Host ''
+ Write-Host ' PROTOCOL TESTS FAILED' -ForegroundColor Red
+ exit 1
+}
+
+Write-Host ''
+Write-Host ' Protocol tests passed.' -ForegroundColor Green
\ No newline at end of file
diff --git a/rsx-protocol/src/main/java/net/rustnotmc/protocol/Buf.java b/rsx-protocol/src/main/java/net/rustnotmc/protocol/Buf.java
new file mode 100644
index 0000000..0fac27d
--- /dev/null
+++ b/rsx-protocol/src/main/java/net/rustnotmc/protocol/Buf.java
@@ -0,0 +1,343 @@
+package net.rustnotmc.protocol;
+
+/**
+ * A growable byte buffer with the primitives the wire format is built from.
+ *
+ * Every read is bounded. A server spends its life taking numbers off sockets
+ * that belong to strangers, and the difference between a cheap check and an
+ * allocation is the difference between a hostile peer costing a few cycles and
+ * costing the heap. Nothing here trusts a length before the bytes behind it
+ * have actually arrived.
+ *
+ * Integers travel as zig-zag varints, so small negatives stay small. The whole
+ * point of that is worth one sentence: negative coordinates are ordinary in a
+ * world, and without zig-zag they would take five bytes each instead of one.
+ */
+public final class Buf {
+
+ /** A varint of a 32 bit value never needs more than five bytes. */
+ public static final int MAX_VAR_INT_BYTES = 5;
+
+ /** A varint of a 64 bit value never needs more than ten bytes. */
+ public static final int MAX_VAR_LONG_BYTES = 10;
+
+ /** Default ceiling for a length-prefixed byte array or string. */
+ public static final int DEFAULT_MAX_PAYLOAD = 2 * 1024 * 1024;
+
+ private byte[] data;
+ private int writerIndex;
+ private int readerIndex;
+
+ public Buf() {
+ this(64);
+ }
+
+ public Buf(int capacity) {
+ if (capacity < 0) {
+ throw new IllegalArgumentException("negative capacity: " + capacity);
+ }
+ this.data = new byte[Math.max(8, capacity)];
+ }
+
+ public Buf(byte[] initial) {
+ this(initial.length);
+ this.writerIndex = initial.length;
+ System.arraycopy(initial, 0, this.data, 0, initial.length);
+ }
+
+ // ------------------------------------------------------------- capacity
+
+ public int readableBytes() {
+ return this.writerIndex - this.readerIndex;
+ }
+
+ public int writerIndex() {
+ return this.writerIndex;
+ }
+
+ /**
+ * Moves the write cursor, used to rewind a buffer that has nothing left in
+ * it. Refuses to move past what has actually been written, because a cursor
+ * past the end would hand out zeroes that were never sent.
+ */
+ public Buf writerIndex(int index) {
+ if (index < 0 || index > this.data.length) {
+ throw new IndexOutOfBoundsException("writer index " + index
+ + " outside 0.." + this.data.length);
+ }
+ this.writerIndex = index;
+ if (this.readerIndex > index) {
+ this.readerIndex = index;
+ }
+ return this;
+ }
+
+ public int readerIndex() {
+ return this.readerIndex;
+ }
+
+ public Buf readerIndex(int index) {
+ if (index < 0 || index > this.writerIndex) {
+ throw new IndexOutOfBoundsException("reader index " + index
+ + " outside 0.." + this.writerIndex);
+ }
+ this.readerIndex = index;
+ return this;
+ }
+
+ private void ensure(int extra) {
+ if (this.writerIndex + extra <= this.data.length) {
+ return;
+ }
+ int needed = this.writerIndex + extra;
+ int grown = Math.max(this.data.length * 2, needed);
+ byte[] bigger = new byte[grown];
+ System.arraycopy(this.data, 0, bigger, 0, this.writerIndex);
+ this.data = bigger;
+ }
+
+ // ---------------------------------------------------------------- write
+
+ public Buf writeByte(int value) {
+ this.ensure(1);
+ this.data[this.writerIndex++] = (byte) value;
+ return this;
+ }
+
+ public Buf writeBoolean(boolean value) {
+ return writeByte(value ? 1 : 0);
+ }
+
+ public Buf writeShort(int value) {
+ this.ensure(2);
+ this.data[this.writerIndex++] = (byte) (value >>> 8);
+ this.data[this.writerIndex++] = (byte) value;
+ return this;
+ }
+
+ public Buf writeInt(int value) {
+ this.ensure(4);
+ this.data[this.writerIndex++] = (byte) (value >>> 24);
+ this.data[this.writerIndex++] = (byte) (value >>> 16);
+ this.data[this.writerIndex++] = (byte) (value >>> 8);
+ this.data[this.writerIndex++] = (byte) value;
+ return this;
+ }
+
+ public Buf writeLong(long value) {
+ this.ensure(8);
+ for (int shift = 56; shift >= 0; shift -= 8) {
+ this.data[this.writerIndex++] = (byte) (value >>> shift);
+ }
+ return this;
+ }
+
+ public Buf writeFloat(float value) {
+ return writeInt(Float.floatToIntBits(value));
+ }
+
+ public Buf writeDouble(double value) {
+ return writeLong(Double.doubleToLongBits(value));
+ }
+
+ /** Writes a zig-zag encoded varint. */
+ public Buf writeVarInt(int value) {
+ int zig = (value << 1) ^ (value >> 31);
+ while (true) {
+ if ((zig & 0xFFFFFF80) == 0) {
+ return writeByte(zig);
+ }
+ writeByte((zig & 0x7F) | 0x80);
+ zig >>>= 7;
+ }
+ }
+
+ /** Writes a zig-zag encoded varint over a long. */
+ public Buf writeVarLong(long value) {
+ long zig = (value << 1) ^ (value >> 63);
+ while (true) {
+ if ((zig & 0xFFFFFFFFFFFFFF80L) == 0L) {
+ return writeByte((int) zig);
+ }
+ writeByte((int) ((zig & 0x7F) | 0x80));
+ zig >>>= 7;
+ }
+ }
+
+ public Buf writeBytes(byte[] value) {
+ return writeBytes(value, 0, value.length);
+ }
+
+ public Buf writeBytes(byte[] value, int offset, int length) {
+ this.ensure(length);
+ System.arraycopy(value, offset, this.data, this.writerIndex, length);
+ this.writerIndex += length;
+ return this;
+ }
+
+ public Buf writeString(String value) {
+ byte[] encoded = value.getBytes(java.nio.charset.StandardCharsets.UTF_8);
+ writeVarInt(encoded.length);
+ return writeBytes(encoded);
+ }
+
+ /**
+ * Writes a block position as one varint.
+ *
+ * The axes do not get equal shares of the long. Three 26 bit fields would be 78
+ * bits and simply do not fit, so the split follows what a world actually needs:
+ * X and Z take 26 bits each, +/-33 million blocks at 1/32 block resolution, and
+ * Y takes the remaining 12 bits as whole blocks in two's complement, covering
+ * -2048 to 2047, which is the whole vertical range the format supports.
+ *
+ * Y is stored signed and not offset by 2048 on purpose: an offset would need 13
+ * bits to hold 0..4095, and the twelfth bit is exactly the one that decides
+ * whether a value reads back negative.
+ *
+ * Every mask is parenthesised on purpose: in Java, << binds tighter than
+ * &, so "a & 0x3FFFFFF << 12" silently masks the wrong value and
+ * throws away the low bits of the axis.
+ */
+public Buf writePosition(double x, double y, double z) {
+ long packed = ((long) (x * 32.0D) & 0x3FFFFFFL) << 38;
+ packed |= ((long) (int) y & 0xFFFL) << 26;
+ packed |= (long) (z * 32.0D) & 0x3FFFFFFL;
+ return writeVarLong(packed);
+ }
+
+ /** Reads a position written by {@link #writePosition}. */
+ public double[] readPosition() {
+ long packed = readVarLong();
+ // a field of n bits at offset k is sign extended by shifting left far
+ // enough to land its top bit at 63, then arithmetically shifting right
+ double x = (double) (packed << 0 >> 38) / 32.0D;
+ double y = (double) (packed << 26 >> 52);
+ double z = (double) (packed << 38 >> 38) / 32.0D;
+ return new double[]{x, y, z};
+ }
+
+ // ----------------------------------------------------------------- read
+
+ public int readUnsignedByte() {
+ require(1);
+ return this.data[this.readerIndex++] & 0xFF;
+ }
+
+ public boolean readBoolean() {
+ return readUnsignedByte() != 0;
+ }
+
+ public int readShort() {
+ require(2);
+ int high = this.data[this.readerIndex++] & 0xFF;
+ int low = this.data[this.readerIndex++] & 0xFF;
+ return (high << 8) | low;
+ }
+
+ public int readInt() {
+ require(4);
+ int value = ((this.data[this.readerIndex++] & 0xFF) << 24)
+ | ((this.data[this.readerIndex++] & 0xFF) << 16)
+ | ((this.data[this.readerIndex++] & 0xFF) << 8)
+ | (this.data[this.readerIndex++] & 0xFF);
+ return value;
+ }
+
+ public long readLong() {
+ require(8);
+ long value = 0L;
+ for (int i = 0; i < 8; i++) {
+ value = (value << 8) | (this.data[this.readerIndex++] & 0xFF);
+ }
+ return value;
+ }
+
+ public float readFloat() {
+ return Float.intBitsToFloat(readInt());
+ }
+
+ public double readDouble() {
+ return Double.longBitsToDouble(readLong());
+ }
+
+ /**
+ * Reads a varint, refusing anything longer than it has to be.
+ *
+ * Without the byte cap a peer can send ten bytes of 0xFF and turn a five
+ * byte integer into an endless loop.
+ */
+ public int readVarInt() {
+ int result = 0;
+ for (int shift = 0; shift < MAX_VAR_INT_BYTES * 7; shift += 7) {
+ byte b = (byte) readUnsignedByte();
+ result |= (b & 0x7F) << shift;
+ if ((b & 0x80) == 0) {
+ return (result >>> 1) ^ -(result & 1);
+ }
+ }
+ throw new ProtocolException("varint is longer than " + MAX_VAR_INT_BYTES + " bytes");
+ }
+
+ public long readVarLong() {
+ long result = 0L;
+ for (int shift = 0; shift < MAX_VAR_LONG_BYTES * 7; shift += 7) {
+ byte b = (byte) readUnsignedByte();
+ result |= (long) (b & 0x7F) << shift;
+ if ((b & 0x80) == 0) {
+ return (result >>> 1) ^ -(result & 1);
+ }
+ }
+ throw new ProtocolException("varlong is longer than " + MAX_VAR_LONG_BYTES + " bytes");
+ }
+
+ public byte[] readBytes(int length) {
+ if (length < 0) {
+ throw new ProtocolException("negative length: " + length);
+ }
+ require(length);
+ byte[] value = new byte[length];
+ System.arraycopy(this.data, this.readerIndex, value, 0, length);
+ this.readerIndex += length;
+ return value;
+ }
+
+ public String readString(int maxLength) {
+ int length = readVarInt();
+ if (length < 0 || length > maxLength) {
+ throw new ProtocolException("string length " + length + " is out of range");
+ }
+ require(length);
+ String value = new String(this.data, this.readerIndex, length,
+ java.nio.charset.StandardCharsets.UTF_8);
+ this.readerIndex += length;
+ return value;
+ }
+
+ /** Bytes written but not yet read, as a copy. */
+ public byte[] toByteArray() {
+ byte[] value = new byte[this.writerIndex];
+ System.arraycopy(this.data, 0, value, 0, this.writerIndex);
+ return value;
+ }
+
+ /** A reader over a slice of what has been written. */
+ public Buf reader() {
+ Buf view = new Buf(Math.max(8, this.writerIndex - this.readerIndex));
+ view.writeBytes(this.data, this.readerIndex, this.writerIndex - this.readerIndex);
+ view.readerIndex = 0;
+ return view;
+ }
+
+ private void require(int count) {
+ if (this.readerIndex + count > this.writerIndex) {
+ throw new IncompleteException("wanted " + count + " byte(s) but only "
+ + readableBytes() + " remain");
+ }
+ }
+
+ @Override
+ public String toString() {
+ return "Buf[read=" + this.readerIndex + ", written=" + this.writerIndex
+ + ", capacity=" + this.data.length + "]";
+ }
+}
\ No newline at end of file
diff --git a/rsx-protocol/src/main/java/net/rustnotmc/protocol/Frame.java b/rsx-protocol/src/main/java/net/rustnotmc/protocol/Frame.java
new file mode 100644
index 0000000..70768ec
--- /dev/null
+++ b/rsx-protocol/src/main/java/net/rustnotmc/protocol/Frame.java
@@ -0,0 +1,144 @@
+package net.rustnotmc.protocol;
+
+/**
+ * One message: an envelope plus the packet body.
+ *
+ * The wire layout is deliberately dull and fixed on both ends:
+ *
+ *
+ * magic 4 bytes 0x52535831, "RSX1"
+ * version varint protocol version, refused if it is not ours
+ * packetId varint what the body means
+ * bodyLength varint bytes of body that follow
+ * body bytes
+ *
+ *
+ * The magic sits in front so a port can answer immediately instead of waiting
+ * to be told it is speaking nonsense. The declared body length is checked
+ * against the maximum before a single byte is reserved, because the only thing
+ * a malicious length is good for is making the server allocate.
+ */
+public final class Frame {
+
+ /** "RSX1" in ASCII, as a big endian int. */
+ public static final int MAGIC = 0x52535831;
+
+ /** The version this build speaks. */
+ public static final int VERSION = 1;
+
+ private final int version;
+ private final int packetId;
+ private final byte[] body;
+
+ public Frame(int packetId, byte[] body) {
+ this(VERSION, packetId, body);
+ }
+
+ public Frame(int version, int packetId, byte[] body) {
+ if (body == null) {
+ throw new IllegalArgumentException("body is null");
+ }
+ this.version = version;
+ this.packetId = packetId;
+ this.body = body;
+ }
+
+ public int version() {
+ return this.version;
+ }
+
+ public int packetId() {
+ return this.packetId;
+ }
+
+ public byte[] body() {
+ return this.body;
+ }
+
+ public int size() {
+ return 4 + MAX_ENVELOPE + this.body.length;
+ }
+
+ /** Worst case envelope: magic plus four varints at their longest. */
+ public static final int MAX_ENVELOPE = 4
+ + Buf.MAX_VAR_INT_BYTES // version
+ + Buf.MAX_VAR_INT_BYTES // packet id
+ + Buf.MAX_VAR_INT_BYTES; // body length
+
+ public Buf encode() {
+ Buf buf = new Buf(size());
+ buf.writeInt(MAGIC);
+ buf.writeVarInt(this.version);
+ buf.writeVarInt(this.packetId);
+ buf.writeVarInt(this.body.length);
+ buf.writeBytes(this.body);
+ return buf;
+ }
+
+ /**
+ * Reads one frame from the front of a buffer.
+ *
+ * Returns null when the buffer does not hold a whole frame yet, so a
+ * caller feeding it a socket can keep the remainder and come back when more
+ * arrives. Throws as soon as it can tell the stream is impossible, rather
+ * than waiting forever for bytes that will make it valid.
+ */
+ public static Frame decode(Buf in, int maxBody) {
+ if (in.readableBytes() < 4) {
+ return null;
+ }
+ int start = in.readerIndex();
+ int magic = peekInt(in);
+ if (magic != MAGIC) {
+ throw new ProtocolException(String.format(
+ "not a RustNotMC stream: magic is 0x%08X", Integer.valueOf(magic)));
+ }
+ in.readerIndex(start + 4);
+
+ int version;
+ int packetId;
+ int length;
+ try {
+ version = in.readVarInt();
+ packetId = in.readVarInt();
+ length = in.readVarInt();
+ } catch (IncompleteException more) {
+ // TCP cut the envelope; the rest is on its way
+ in.readerIndex(start);
+ return null;
+ } catch (ProtocolException malformed) {
+ throw new ProtocolException("malformed envelope: " + malformed.getMessage(), malformed);
+ }
+
+ if (version != VERSION) {
+ throw new ProtocolException("protocol version " + version
+ + ", this build speaks " + VERSION);
+ }
+ if (length < 0 || length > maxBody) {
+ throw new ProtocolException("declared body of " + length
+ + " bytes is outside the limit of " + maxBody);
+ }
+ if (in.readableBytes() < length) {
+ in.readerIndex(start);
+ return null;
+ }
+ byte[] body = in.readBytes(length);
+ return new Frame(version, packetId, body);
+ }
+
+ private static int peekInt(Buf in) {
+ int r = in.readerIndex();
+ int value = ((in.readUnsignedByte() & 0xFF) << 24)
+ | ((in.readUnsignedByte() & 0xFF) << 16)
+ | ((in.readUnsignedByte() & 0xFF) << 8)
+ | (in.readUnsignedByte() & 0xFF);
+ in.readerIndex(r);
+ return value;
+ }
+
+ @Override
+ public String toString() {
+ return "Frame[id=" + this.packetId + ", version=" + this.version
+ + ", body=" + this.body.length + "B]";
+ }
+}
\ No newline at end of file
diff --git a/rsx-protocol/src/main/java/net/rustnotmc/protocol/FrameDecoder.java b/rsx-protocol/src/main/java/net/rustnotmc/protocol/FrameDecoder.java
new file mode 100644
index 0000000..11886e3
--- /dev/null
+++ b/rsx-protocol/src/main/java/net/rustnotmc/protocol/FrameDecoder.java
@@ -0,0 +1,124 @@
+package net.rustnotmc.protocol;
+
+/**
+ * Turns a byte stream into frames, one call per whatever the socket had.
+ *
+ * TCP hands over bytes, not messages: one read may be half a frame, or nine
+ * and a half. The decoder keeps whatever it could not use yet and returns only
+ * whole frames, so the layer above sees a stream of packets and never thinks
+ * about segmentation again.
+ *
+ * The one thing it will not do is buffer without limit. A peer that announces
+ * a body of a gigabyte and then sends nothing must not be able to hold a
+ * gigabyte of this process's heap, so a body larger than the configured
+ * ceiling is refused the moment its length is read.
+ */
+public final class FrameDecoder {
+
+ private final Buf pending;
+ private final int maxBody;
+
+ private boolean poisoned;
+ private int framesRead;
+ private long bytesRead;
+
+ public FrameDecoder() {
+ this(Buf.DEFAULT_MAX_PAYLOAD);
+ }
+
+ public FrameDecoder(int maxBody) {
+ if (maxBody <= 0) {
+ throw new IllegalArgumentException("max body must be positive: " + maxBody);
+ }
+ this.pending = new Buf();
+ this.maxBody = maxBody;
+ }
+
+ public int maxBody() {
+ return this.maxBody;
+ }
+
+ public int bufferedBytes() {
+ return this.pending.readableBytes();
+ }
+
+ public int framesRead() {
+ return this.framesRead;
+ }
+
+ public long bytesRead() {
+ return this.bytesRead;
+ }
+
+ /**
+ * Feeds freshly read bytes in.
+ *
+ * Returns every frame that is now complete. Throws on a stream that can no
+ * longer become valid; a caller should treat that as the end of the
+ * connection rather than something to retry.
+ */
+ public java.util.List offer(byte[] chunk, int offset, int length) {
+ if (this.poisoned) {
+ throw new ProtocolException("decoder was poisoned by an earlier failure");
+ }
+ if (chunk == null) {
+ throw new IllegalArgumentException("chunk is null");
+ }
+ if (length < 0 || offset < 0 || offset + length > chunk.length) {
+ throw new IllegalArgumentException("chunk range is out of bounds");
+ }
+ if (length == 0) {
+ return java.util.Collections.emptyList();
+ }
+ this.pending.writeBytes(chunk, offset, length);
+ this.bytesRead += length;
+
+ // refuse to sit on more than one maximum frame plus a partial header
+ int ceiling = this.maxBody + Frame.MAX_ENVELOPE;
+ if (this.pending.readableBytes() > ceiling) {
+ this.poisoned = true;
+ throw new ProtocolException("buffered " + this.pending.readableBytes()
+ + " bytes without a complete frame, limit is " + ceiling);
+ }
+
+ java.util.List out = new java.util.ArrayList();
+ while (true) {
+ Frame frame;
+ try {
+ frame = Frame.decode(this.pending, this.maxBody);
+ } catch (ProtocolException bad) {
+ this.poisoned = true;
+ throw bad;
+ }
+ if (frame == null) {
+ break;
+ }
+ this.framesRead++;
+ out.add(frame);
+ }
+ // hand the tail back to the next read instead of growing the buffer
+ this.compact();
+ return out;
+ }
+
+ private void compact() {
+ // keep the original object: callers may be holding it, and replacing the
+ // field under them would be a nasty surprise
+ int left = this.pending.readableBytes();
+ int from = this.pending.readerIndex();
+ if (left == 0) {
+ this.pending.readerIndex(0);
+ this.pending.writerIndex(0);
+ return;
+ }
+ if (from == 0) {
+ return;
+ }
+ byte[] all = this.pending.toByteArray();
+ byte[] tail = new byte[left];
+ System.arraycopy(all, from, tail, 0, left);
+ this.pending.readerIndex(0);
+ this.pending.writerIndex(0);
+ this.pending.writeBytes(tail);
+ }
+}
\ No newline at end of file
diff --git a/rsx-protocol/src/main/java/net/rustnotmc/protocol/IncompleteException.java b/rsx-protocol/src/main/java/net/rustnotmc/protocol/IncompleteException.java
new file mode 100644
index 0000000..e14a5f5
--- /dev/null
+++ b/rsx-protocol/src/main/java/net/rustnotmc/protocol/IncompleteException.java
@@ -0,0 +1,19 @@
+package net.rustnotmc.protocol;
+
+/**
+ * Raised when a buffer does not yet hold the bytes a read asked for.
+ *
+ * Separate from {@link ProtocolException} because the two mean opposite things.
+ * Running out of bytes is normal: TCP cut a frame in half and the rest is on
+ * its way. A malformed varint is not normal and the stream is finished. If the
+ * decoder treated both as fatal it would drop every connection that happened to
+ * span two packets, which on a real network is most of them.
+ */
+public final class IncompleteException extends ProtocolException {
+
+ private static final long serialVersionUID = 1L;
+
+ public IncompleteException(String message) {
+ super(message);
+ }
+}
\ No newline at end of file
diff --git a/rsx-protocol/src/main/java/net/rustnotmc/protocol/Packets.java b/rsx-protocol/src/main/java/net/rustnotmc/protocol/Packets.java
new file mode 100644
index 0000000..b5a8947
--- /dev/null
+++ b/rsx-protocol/src/main/java/net/rustnotmc/protocol/Packets.java
@@ -0,0 +1,266 @@
+package net.rustnotmc.protocol;
+
+import java.util.LinkedHashMap;
+import java.util.Map;
+
+/**
+ * The packets that start a connection, and the table that maps them to ids.
+ *
+ * The ids are written down here rather than generated, because they end up in
+ * every capture and every log line forever. Renumbering one is a protocol
+ * change and should look like a deliberate act, not a side effect of moving a
+ * class around.
+ *
+ * The order of a connection is fixed and short:
+ *
+ *
+ * client -> Hello protocol version, what the client is
+ * server -> HelloAck accepted version, server name, motd, online count
+ * client -> Auth account and proof
+ * server -> AuthAck session token, or a reason it was refused
+ * client -> Login the session token
+ * server -> LoginAck player id and entity id, or a reason
+ * either -> Disconnect a human readable reason
+ *
+ */
+public final class Packets {
+
+ private Packets() {
+ }
+
+ /** Longest a name, motd or reason may be, in bytes. */
+ public static final int MAX_TEXT = 512;
+
+ /** Longest a handshake proof may be, in bytes. */
+ public static final int MAX_PROOF = 256;
+
+ /** Longest the handshake body may be, in bytes. */
+ public static final int MAX_HANDSHAKE_BODY = 8 * 1024;
+
+ public static final int HELLO = 0x01;
+ public static final int HELLO_ACK = 0x02;
+ public static final int AUTH = 0x03;
+ public static final int AUTH_ACK = 0x04;
+ public static final int LOGIN = 0x05;
+ public static final int LOGIN_ACK = 0x06;
+ public static final int DISCONNECT = 0x7F;
+
+ /** The client introducing itself. */
+ public static final class Hello {
+ public final int protocolVersion;
+ public final String clientName;
+ public final int clientVersion;
+
+ public Hello(int protocolVersion, String clientName, int clientVersion) {
+ this.protocolVersion = protocolVersion;
+ this.clientName = clientName;
+ this.clientVersion = clientVersion;
+ }
+
+ public Buf write() {
+ Buf buf = new Buf();
+ buf.writeVarInt(this.protocolVersion);
+ buf.writeString(this.clientName);
+ buf.writeVarInt(this.clientVersion);
+ return buf;
+ }
+
+ public static Hello read(Buf in) {
+ return new Hello(in.readVarInt(), in.readString(MAX_TEXT), in.readVarInt());
+ }
+ }
+
+ /** The server accepting, and describing itself. */
+ public static final class HelloAck {
+ public final int protocolVersion;
+ public final String serverName;
+ public final String motd;
+ public final int onlinePlayers;
+ public final int maxPlayers;
+
+ public HelloAck(int protocolVersion, String serverName, String motd,
+ int onlinePlayers, int maxPlayers) {
+ this.protocolVersion = protocolVersion;
+ this.serverName = serverName;
+ this.motd = motd;
+ this.onlinePlayers = onlinePlayers;
+ this.maxPlayers = maxPlayers;
+ }
+
+ public Buf write() {
+ Buf buf = new Buf();
+ buf.writeVarInt(this.protocolVersion);
+ buf.writeString(this.serverName);
+ buf.writeString(this.motd);
+ buf.writeVarInt(this.onlinePlayers);
+ buf.writeVarInt(this.maxPlayers);
+ return buf;
+ }
+
+ public static HelloAck read(Buf in) {
+ return new HelloAck(in.readVarInt(), in.readString(MAX_TEXT),
+ in.readString(MAX_TEXT), in.readVarInt(), in.readVarInt());
+ }
+ }
+
+ /** The client claiming an account. */
+ public static final class Auth {
+ public final String account;
+ public final String proof;
+
+ public Auth(String account, String proof) {
+ this.account = account;
+ this.proof = proof;
+ }
+
+ public Buf write() {
+ Buf buf = new Buf();
+ buf.writeString(this.account);
+ buf.writeString(this.proof);
+ return buf;
+ }
+
+ public static Auth read(Buf in) {
+ return new Auth(in.readString(MAX_TEXT), in.readString(MAX_PROOF));
+ }
+ }
+
+ /** Whether the account was accepted, and on what terms. */
+ public static final class AuthAck {
+ public final boolean accepted;
+ public final String reason;
+ public final String token;
+ public final long expiresAt;
+
+ private AuthAck(boolean accepted, String reason, String token, long expiresAt) {
+ this.accepted = accepted;
+ this.reason = reason;
+ this.token = token;
+ this.expiresAt = expiresAt;
+ }
+
+ public static AuthAck ok(String token, long expiresAt) {
+ return new AuthAck(true, "", token, expiresAt);
+ }
+
+ public static AuthAck refused(String reason) {
+ return new AuthAck(false, reason, "", 0L);
+ }
+
+ public Buf write() {
+ Buf buf = new Buf();
+ buf.writeBoolean(this.accepted);
+ buf.writeString(this.reason);
+ if (this.accepted) {
+ buf.writeString(this.token);
+ buf.writeLong(this.expiresAt);
+ }
+ return buf;
+ }
+
+ public static AuthAck read(Buf in) {
+ if (!in.readBoolean()) {
+ return refused(in.readString(MAX_TEXT));
+ }
+ return ok(in.readString(MAX_TEXT), in.readLong());
+ }
+ }
+
+ /** The client redeeming the token it was just handed. */
+ public static final class Login {
+ public final String account;
+ public final String token;
+
+ public Login(String account, String token) {
+ this.account = account;
+ this.token = token;
+ }
+
+ public Buf write() {
+ Buf buf = new Buf();
+ buf.writeString(this.account);
+ buf.writeString(this.token);
+ return buf;
+ }
+
+ public static Login read(Buf in) {
+ return new Login(in.readString(MAX_TEXT), in.readString(MAX_TEXT));
+ }
+ }
+
+ /** Whether the player is in. */
+ public static final class LoginAck {
+ public final boolean accepted;
+ public final String reason;
+ public final int playerId;
+ public final int entityId;
+
+ private LoginAck(boolean accepted, String reason, int playerId, int entityId) {
+ this.accepted = accepted;
+ this.reason = reason;
+ this.playerId = playerId;
+ this.entityId = entityId;
+ }
+
+ public static LoginAck ok(int playerId, int entityId) {
+ return new LoginAck(true, "", playerId, entityId);
+ }
+
+ public static LoginAck refused(String reason) {
+ return new LoginAck(false, reason, -1, -1);
+ }
+
+ public Buf write() {
+ Buf buf = new Buf();
+ buf.writeBoolean(this.accepted);
+ buf.writeString(this.reason);
+ if (this.accepted) {
+ buf.writeVarInt(this.playerId);
+ buf.writeVarInt(this.entityId);
+ }
+ return buf;
+ }
+
+ public static LoginAck read(Buf in) {
+ if (!in.readBoolean()) {
+ return refused(in.readString(MAX_TEXT));
+ }
+ return ok(in.readVarInt(), in.readVarInt());
+ }
+ }
+
+ /** A reason, said out loud, before the connection goes away. */
+ public static final class Disconnect {
+ public final String reason;
+
+ public Disconnect(String reason) {
+ this.reason = reason;
+ }
+
+ public Buf write() {
+ return new Buf().writeString(this.reason);
+ }
+
+ public static Disconnect read(Buf in) {
+ return new Disconnect(in.readString(MAX_TEXT));
+ }
+ }
+
+ /**
+ * Every packet id this build knows, and what it decodes into.
+ *
+ * Written as plain data so that adding a packet is one line and an unknown
+ * id is a loud error instead of a silent skip.
+ */
+ public static Map names() {
+ Map map = new LinkedHashMap();
+ map.put(Integer.valueOf(HELLO), "Hello");
+ map.put(Integer.valueOf(HELLO_ACK), "HelloAck");
+ map.put(Integer.valueOf(AUTH), "Auth");
+ map.put(Integer.valueOf(AUTH_ACK), "AuthAck");
+ map.put(Integer.valueOf(LOGIN), "Login");
+ map.put(Integer.valueOf(LOGIN_ACK), "LoginAck");
+ map.put(Integer.valueOf(DISCONNECT), "Disconnect");
+ return map;
+ }
+}
\ No newline at end of file
diff --git a/rsx-protocol/src/main/java/net/rustnotmc/protocol/ProtocolException.java b/rsx-protocol/src/main/java/net/rustnotmc/protocol/ProtocolException.java
new file mode 100644
index 0000000..7f207f5
--- /dev/null
+++ b/rsx-protocol/src/main/java/net/rustnotmc/protocol/ProtocolException.java
@@ -0,0 +1,21 @@
+package net.rustnotmc.protocol;
+
+/**
+ * Raised when bytes on the wire cannot mean what the sender intended.
+ *
+ * Unchecked on purpose: every one of these ends the connection, and there is
+ * nothing a caller could do about it other than close. Making it checked would
+ * only add a catch block that rethrows.
+ */
+public class ProtocolException extends RuntimeException {
+
+ private static final long serialVersionUID = 1L;
+
+ public ProtocolException(String message) {
+ super(message);
+ }
+
+ public ProtocolException(String message, Throwable cause) {
+ super(message, cause);
+ }
+}
\ No newline at end of file
diff --git a/rsx-protocol/src/test/java/net/rustnotmc/protocol/ProtocolTest.java b/rsx-protocol/src/test/java/net/rustnotmc/protocol/ProtocolTest.java
new file mode 100644
index 0000000..78eb20f
--- /dev/null
+++ b/rsx-protocol/src/test/java/net/rustnotmc/protocol/ProtocolTest.java
@@ -0,0 +1,407 @@
+package net.rustnotmc.protocol;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Random;
+
+/**
+ * Tests for the wire format.
+ *
+ * These are not example code. Every case here is something a hostile or simply
+ * broken peer can actually do, and the point of the test is that the server
+ * survives it without an OutOfMemoryError, an endless loop or a silent
+ * misinterpretation.
+ */
+public final class ProtocolTest {
+
+ private static int checks;
+ private static int failed;
+ private static final List failures = new ArrayList();
+
+ public static void main(String[] args) {
+ run("varint round trip", new Runnable() {
+ public void run() { testVarInt(); }
+ });
+ run("varint rejects overlong input", new Runnable() {
+ public void run() { testVarIntOverlong(); }
+ });
+ run("negative numbers stay small", new Runnable() {
+ public void run() { testVarIntZigZag(); }
+ });
+ run("varlong round trip", new Runnable() {
+ public void run() { testVarLong(); }
+ });
+ run("fixed width round trip", new Runnable() {
+ public void run() { testFixedWidth(); }
+ });
+ run("string round trip incl. non ascii", new Runnable() {
+ public void run() { testString(); }
+ });
+ run("string length is bounded", new Runnable() {
+ public void run() { testStringBound(); }
+ });
+ run("reading past the end fails", new Runnable() {
+ public void run() { testUnderflow(); }
+ });
+ run("position survives the round trip", new Runnable() {
+ public void run() { testPosition(); }
+ });
+ run("frame round trip", new Runnable() {
+ public void run() { testFrame(); }
+ });
+ run("partial frame decodes to nothing", new Runnable() {
+ public void run() { testPartialFrame(); }
+ });
+ run("foreign magic is refused", new Runnable() {
+ public void run() { testWrongMagic(); }
+ });
+ run("oversized declared body is refused", new Runnable() {
+ public void run() { testOversizedClaim(); }
+ });
+ run("byte at a time still works", new Runnable() {
+ public void run() { testSplitEverywhere(); }
+ });
+ run("many frames in one read", new Runnable() {
+ public void run() { testBatch(); }
+ });
+ run("handshake packets round trip", new Runnable() {
+ public void run() { testHandshake(); }
+ });
+ run("a lying length cannot stall the heap", new Runnable() {
+ public void run() { testLyingLength(); }
+ });
+
+ System.out.println();
+ for (int i = 0; i < failures.size(); i++) {
+ System.out.println(" FAIL " + failures.get(i));
+ }
+ System.out.println();
+ System.out.println("checks: " + checks + ", failed: " + failed);
+ if (failed != 0) {
+ System.out.println("FAILED");
+ System.exit(1);
+ }
+ System.out.println("OK");
+ }
+
+ private static void run(String name, Runnable body) {
+ checks++;
+ int before = failed;
+ try {
+ body.run();
+ } catch (Throwable t) {
+ failed++;
+ failures.add(name + ": threw " + t);
+ t.printStackTrace();
+ return;
+ }
+ if (failed == before) {
+ System.out.println(" ok " + name);
+ } else {
+ failures.add(name + ": assertions failed");
+ }
+ }
+
+ private static void eq(Object what, Object expected, Object actual) {
+ // arrays compare by reference under equals(), which is never what a
+ // caller means when it hands over a body
+ if (expected instanceof byte[] && actual instanceof byte[]) {
+ if (!java.util.Arrays.equals((byte[]) expected, (byte[]) actual)) {
+ failed++;
+ failures.add(what + ": byte arrays differ");
+ }
+ return;
+ }
+ if (expected == null ? actual != null : !expected.equals(actual)) {
+ failed++;
+ failures.add(what + ": expected " + expected + " but got " + actual);
+ }
+ }
+
+ private static void yes(String what, boolean condition) {
+ if (!condition) {
+ failed++;
+ failures.add(what);
+ }
+ }
+
+ private static void refuses(String what, Runnable body) {
+ try {
+ body.run();
+ failed++;
+ failures.add(what + ": accepted something it should have refused");
+ } catch (ProtocolException expected) {
+ // exactly what we want
+ } catch (Throwable other) {
+ failed++;
+ failures.add(what + ": threw " + other + " instead of ProtocolException");
+ }
+ }
+
+ // ------------------------------------------------------------- the tests
+
+ private static void testVarInt() {
+ int[] values = {0, 1, -1, 127, 128, -128, 12345, -12345,
+ Integer.MAX_VALUE, Integer.MIN_VALUE};
+ for (int i = 0; i < values.length; i++) {
+ Buf buf = new Buf();
+ buf.writeVarInt(values[i]);
+ eq("varint " + values[i], Integer.valueOf(values[i]),
+ Integer.valueOf(new Buf(buf.toByteArray()).readVarInt()));
+ }
+ }
+
+ private static void testVarIntOverlong() {
+ // ten bytes of 0xFF: a five byte value cannot be this long
+ byte[] evil = new byte[10];
+ java.util.Arrays.fill(evil, (byte) 0xFF);
+ refuses("overlong varint", new Runnable() {
+ public void run() { new Buf(evil).readVarInt(); }
+ });
+ }
+
+ private static void testVarIntZigZag() {
+ Buf small = new Buf();
+ small.writeVarInt(-1);
+ yes("minus one is one byte, not five", small.writerIndex() == 1);
+
+ Buf zero = new Buf();
+ zero.writeVarInt(0);
+ yes("zero is one byte", zero.writerIndex() == 1);
+
+ Buf positive = new Buf();
+ positive.writeVarInt(63);
+ Buf negative = new Buf();
+ negative.writeVarInt(-63);
+ eq("63 and -63 cost the same", Integer.valueOf(positive.writerIndex()),
+ Integer.valueOf(negative.writerIndex()));
+ }
+
+ private static void testVarLong() {
+ long[] values = {0L, 1L, -1L, Long.MAX_VALUE, Long.MIN_VALUE, -1234567890123L};
+ for (int i = 0; i < values.length; i++) {
+ Buf buf = new Buf();
+ buf.writeVarLong(values[i]);
+ eq("varlong " + values[i], Long.valueOf(values[i]),
+ Long.valueOf(new Buf(buf.toByteArray()).readVarLong()));
+ }
+ }
+
+ private static void testFixedWidth() {
+ Buf buf = new Buf();
+ buf.writeBoolean(true);
+ buf.writeByte(0x7F);
+ buf.writeShort(0xBEEF);
+ buf.writeInt(-559038737);
+ buf.writeLong(-1234567890123L);
+ buf.writeFloat(0.5F);
+ buf.writeDouble(-2.25D);
+
+ Buf read = new Buf(buf.toByteArray());
+ yes("boolean", read.readBoolean());
+ eq("byte", Integer.valueOf(0x7F), Integer.valueOf(read.readUnsignedByte()));
+ eq("short", Integer.valueOf(0xBEEF), Integer.valueOf(read.readShort()));
+ eq("int", Integer.valueOf(-559038737), Integer.valueOf(read.readInt()));
+ eq("long", Long.valueOf(-1234567890123L), Long.valueOf(read.readLong()));
+ eq("float", Float.valueOf(0.5F), Float.valueOf(read.readFloat()));
+ eq("double", Double.valueOf(-2.25D), Double.valueOf(read.readDouble()));
+ eq("nothing left", Integer.valueOf(0), Integer.valueOf(read.readableBytes()));
+ }
+
+ private static void testString() {
+ String[] values = {"", "player", "Игрок", "a name with spaces", "~!@#$%^&*()"};
+ for (int i = 0; i < values.length; i++) {
+ Buf buf = new Buf();
+ buf.writeString(values[i]);
+ eq("string " + values[i], values[i],
+ new Buf(buf.toByteArray()).readString(Packets.MAX_TEXT));
+ }
+ }
+
+ private static void testStringBound() {
+ // announces a huge string and then does not send it
+ Buf buf = new Buf();
+ buf.writeVarInt(0x7FFFFFF0);
+ refuses("string longer than the limit", new Runnable() {
+ public void run() { buf.readString(Packets.MAX_TEXT); }
+ });
+ }
+
+ private static void testUnderflow() {
+ refuses("reading past the end", new Runnable() {
+ public void run() { new Buf(new byte[2]).readInt(); }
+ });
+ }
+
+ private static void testPosition() {
+ // Y is deliberately whole blocks: it only has 12 bits, so it is stored
+ // as a signed block number and a fractional Y is quantised away
+ double[][] positions = {
+ {0.0D, 0.0D, 0.0D},
+ {1.5D, -64.0D, 300.25D},
+ {-1234.5D, 319.0D, -4096.75D},
+ {0.03125D, -2048.0D, 0.03125D},
+ {0.03125D, 2047.0D, 0.03125D},
+ };
+ for (int i = 0; i < positions.length; i++) {
+ double[] p = positions[i];
+ Buf buf = new Buf();
+ buf.writePosition(p[0], p[1], p[2]);
+ double[] back = new Buf(buf.toByteArray()).readPosition();
+ eq("position x " + p[0], Double.valueOf(p[0]), Double.valueOf(back[0]));
+ eq("position y " + p[1], Double.valueOf(p[1]), Double.valueOf(back[1]));
+ eq("position z " + p[2], Double.valueOf(p[2]), Double.valueOf(back[2]));
+ }
+
+ // and the quantisation is a documented property, not an accident
+ Buf fractional = new Buf();
+ fractional.writePosition(1.0D, 64.5D, 2.0D);
+ double[] cut = new Buf(fractional.toByteArray()).readPosition();
+ eq("fractional Y rounds to a whole block", Double.valueOf(64.0), Double.valueOf(cut[1]));
+ }
+
+ private static void testFrame() {
+ byte[] body = new byte[300];
+ new Random(7).nextBytes(body);
+ Frame frame = new Frame(Packets.HELLO, body);
+ Buf encoded = frame.encode();
+ Frame back = Frame.decode(encoded, 1024 * 1024);
+ yes("frame came back", back != null);
+ eq("frame id", Integer.valueOf(Packets.HELLO), Integer.valueOf(back.packetId()));
+ eq("frame version", Integer.valueOf(Frame.VERSION), Integer.valueOf(back.version()));
+ yes("frame body", java.util.Arrays.equals(body, back.body()));
+ }
+
+ private static void testPartialFrame() {
+ Buf encoded = new Frame(Packets.LOGIN, new byte[64]).encode();
+ byte[] all = encoded.toByteArray();
+ // a fresh decoder per prefix: the question is whether any prefix short of
+ // the whole frame decodes to nothing, not what happens when prefixes are
+ // concatenated into one stream
+ for (int cut = 0; cut < all.length - 1; cut++) {
+ FrameDecoder decoder = new FrameDecoder();
+ List got = decoder.offer(all, 0, cut);
+ yes("nothing complete after " + cut + " bytes", got.isEmpty());
+ }
+ FrameDecoder whole = new FrameDecoder();
+ for (int cut = 0; cut < all.length; cut++) {
+ whole.offer(all, cut, 1);
+ }
+ eq("exactly one frame once it all arrived", Integer.valueOf(1),
+ Integer.valueOf(whole.framesRead()));
+ }
+
+ private static void testWrongMagic() {
+ byte[] notOurs = new byte[] {0x7F, 'E', 'L', 'F', 0x01, 0x00, 0x00, 0x00};
+ FrameDecoder decoder = new FrameDecoder();
+ refuses("foreign magic", new Runnable() {
+ public void run() { decoder.offer(notOurs, 0, notOurs.length); }
+ });
+ }
+
+ private static void testOversizedClaim() {
+ // valid magic and version, but a body of two gigabytes
+ Buf buf = new Buf();
+ buf.writeInt(Frame.MAGIC);
+ buf.writeVarInt(Frame.VERSION);
+ buf.writeVarInt(Packets.HELLO);
+ buf.writeVarInt(Integer.MAX_VALUE);
+ byte[] bytes = buf.toByteArray();
+ FrameDecoder decoder = new FrameDecoder(4096);
+ refuses("oversized claim", new Runnable() {
+ public void run() { decoder.offer(bytes, 0, bytes.length); }
+ });
+ }
+
+ private static void testSplitEverywhere() {
+ List expected = new ArrayList();
+ expected.add(new Frame(Packets.HELLO, body("hello")));
+ expected.add(new Frame(Packets.HELLO_ACK, body("hello-ack")));
+ expected.add(new Frame(Packets.AUTH, body("auth")));
+ expected.add(new Frame(Packets.AUTH_ACK, body("auth-ack")));
+ expected.add(new Frame(Packets.LOGIN, body("login")));
+ expected.add(new Frame(Packets.LOGIN_ACK, body("login-ack")));
+ expected.add(new Frame(Packets.DISCONNECT, body("disconnect")));
+
+ Buf all = new Buf();
+ for (int i = 0; i < expected.size(); i++) {
+ all.writeBytes(expected.get(i).encode().toByteArray());
+ }
+ byte[] wire = all.toByteArray();
+
+ FrameDecoder decoder = new FrameDecoder();
+ List got = new ArrayList();
+ for (int i = 0; i < wire.length; i++) {
+ got.addAll(decoder.offer(wire, i, 1));
+ }
+ eq("every frame arrived", Integer.valueOf(expected.size()), Integer.valueOf(got.size()));
+ for (int i = 0; i < expected.size() && i < got.size(); i++) {
+ eq("frame " + i + " id", Integer.valueOf(expected.get(i).packetId()),
+ Integer.valueOf(got.get(i).packetId()));
+ yes("frame " + i + " body",
+ java.util.Arrays.equals(expected.get(i).body(), got.get(i).body()));
+ }
+ eq("nothing left buffered", Integer.valueOf(0), Integer.valueOf(decoder.bufferedBytes()));
+ }
+
+ private static void testBatch() {
+ FrameDecoder decoder = new FrameDecoder();
+ List all = new ArrayList();
+ Buf wire = new Buf();
+ for (int i = 0; i < 50; i++) {
+ Frame frame = new Frame(Packets.LOGIN, ("frame-" + i).getBytes());
+ all.add(frame);
+ wire.writeBytes(frame.encode().toByteArray());
+ }
+ byte[] bytes = wire.toByteArray();
+ List got = decoder.offer(bytes, 0, bytes.length);
+ eq("all fifty in one read", Integer.valueOf(50), Integer.valueOf(got.size()));
+ eq("counter agrees", Integer.valueOf(50), Integer.valueOf(decoder.framesRead()));
+ for (int i = 0; i < got.size(); i++) {
+ eq("body " + i, all.get(i).body(), got.get(i).body());
+ }
+ }
+
+ private static byte[] body(String text) {
+ return new Buf().writeString(text).toByteArray();
+ }
+
+ private static void testHandshake() {
+ // the shapes the handshake relies on, exercised through the buffer
+ Buf b = new Buf();
+ b.writeString("Player");
+ eq("account name", "Player", new Buf(b.toByteArray()).readString(Packets.MAX_TEXT));
+
+ Buf t = new Buf();
+ t.writeString("proof-token-value");
+ eq("proof", "proof-token-value", new Buf(t.toByteArray()).readString(Packets.MAX_PROOF));
+
+ Buf n = new Buf();
+ n.writeVarInt(200);
+ n.writeVarInt(500);
+ Buf nr = new Buf(n.toByteArray());
+ eq("online", Integer.valueOf(200), Integer.valueOf(nr.readVarInt()));
+ eq("max", Integer.valueOf(500), Integer.valueOf(nr.readVarInt()));
+ }
+
+ private static void testLyingLength() {
+ // announces a large but legal body, sends nothing, and keeps quiet.
+ // The decoder must hold it without growing and without pretending the
+ // frame arrived.
+ FrameDecoder decoder = new FrameDecoder(64 * 1024);
+ Buf header = new Buf();
+ header.writeInt(Frame.MAGIC);
+ header.writeVarInt(Frame.VERSION);
+ header.writeVarInt(Packets.HELLO);
+ header.writeVarInt(60 * 1024);
+ byte[] bytes = header.toByteArray();
+ List got = decoder.offer(bytes, 0, bytes.length);
+ yes("no frame yet", got.isEmpty());
+ yes("held the header", decoder.bufferedBytes() == bytes.length);
+
+ // and the rest arrives, so it completes
+ byte[] body = new byte[60 * 1024];
+ got = decoder.offer(body, 0, body.length);
+ eq("completes once the body arrives", Integer.valueOf(1), Integer.valueOf(got.size()));
+ }
+}
\ No newline at end of file