Build 0.20.8.0

2022-11-25 19:56:30 +02:00
parent ecb6d40b4b
commit df805574c4
111 changed files with 2347 additions and 1283 deletions
@@ -0,0 +1,336 @@
+#nullable enable
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using Microsoft.Xna.Framework;
+
+namespace Barotrauma.Networking;
+
+/*
+ * What are segment tables for?
+ *
+ * Segment tables help make our networking packet reading code more robust by
+ * clearly stating where part of a message begins. Previously we would've done
+ * something like:
+ *
+ *      msg.WriteByte(SegmentType.A);
+ *      ...
+ *      msg.WriteByte(SegmentType.B);
+ *      ...
+ *      msg.WriteByte(SegmentType.EndOfMessage);
+ *
+ * The problem with this design is that it's hard to debug when the writing and reading
+ * code do not align for whatever reason. INetSerializableStruct is an awesome way
+ * of avoiding that problem, but deploying it on a broad scale means rewriting most
+ * of the netcode. That isn't going to happen any time soon, so this exists as an easier
+ * way of increasing robustness.
+ *
+ * A segment table is laid out as follows:
+ *
+ * [TablePointer: UInt16]
+ * [Segment: arbitrary]
+ * ...
+ * [Segment: arbitrary]
+ * [NumberOfSegments: UInt16]
+ * [(Identifier, SegmentPointer): (T, UInt16)]
+ * ...
+ * [(Identifier, SegmentPointer): (T, UInt16)]
+ *
+ * A pointer in this context is an offset relative to the BitPosition where the TablePointer is written.
+ *
+ * It is used as follows:
+ * 
+ *      using (var segmentTable = SegmentTableWriter<T>.StartWriting(outMsg))
+ *      {
+ *          segmentTable.StartNewSegment(T.A);
+ *          ... write segment to outMsg ...
+ *          segmentTable.StartNewSegment(T.B);
+ *          ... write segment to outMsg ...
+ *      }
+ *      peer.SendMessage(outMsg);
+ *
+ *      ...
+ *
+ *      SegmentTableReader<T>.Read(inc,
+ *          segmentDataReader: (segment, inc) =>
+ *          {
+ *              switch (segment)
+ *              {
+ *                 ... read segments ...
+ *              }
+ *          }
+ *      }
+ * 
+ * The advantages of this approach are:
+ * - If a message is truncated or corrupted near the end, it becomes far more obvious because the table
+ *   would not be read properly and look like garbage when printed to the console.
+ * - If the reading and writing code for a segment disagree on something, issues will be isolated to that
+ *   one segment.
+ * - The code no longer has to fiddle with padding and temporary buffers because the segment table is able
+ *   to handle content that is not byte-aligned just fine.
+ * - Exception handling is far easier when using a segment table, when combined with a using statement
+ *   any uncaught exception will result in the entire table being skipped, allowing the remainder of the
+ *   message to still be read.
+ * - It's harder to make mistakes in the implementation of segments themselves with this approach. By using
+ *   the SegmentTableWriter and SegmentTableReader types, you get a type-safe way of delimiting segments
+ *   and it's harder to forget to finalize a packet.
+ */
+
+[NetworkSerialize]
+public readonly record struct Segment<T>(T Identifier, UInt16 Pointer) : INetSerializableStruct where T : struct;
+
+readonly ref struct SegmentTableWriter<T> where T : struct
+{
+    private readonly IWriteMessage message;
+    private readonly List<Segment<T>> segments;
+    public readonly int PointerLocation;
+    private SegmentTableWriter(IWriteMessage message, int pointerLocation)
+    {
+        this.message = message;
+        this.PointerLocation = pointerLocation;
+        this.segments = new List<Segment<T>>();
+    }
+
+    public static SegmentTableWriter<T> StartWriting(IWriteMessage msg)
+    {
+        var retVal = new SegmentTableWriter<T>(msg, msg.BitPosition);
+        msg.WriteUInt16(0); //reserve space for the table pointer
+        return retVal;
+    }
+
+    private void ThrowOnInvalidState()
+    {
+        if (segments.Count >= UInt16.MaxValue)
+        {
+            throw new InvalidOperationException($"Too many segments in SegmentTable<{typeof(T).Name}>");
+        }
+
+        if (message.BitPosition - PointerLocation > UInt16.MaxValue)
+        {
+            throw new OverflowException(
+                $"Too much data is being stored in SegmentTable<{typeof(T).Name}> ({segments.Count} segments)");
+        }
+    }
+    
+    public void StartNewSegment(T value)
+    {
+        ThrowOnInvalidState();
+        segments.Add(new Segment<T>(value, (UInt16)(message.BitPosition-PointerLocation)));
+    }
+
+    public void Dispose()
+    {
+        ThrowOnInvalidState();
+        int tablePosition = message.BitPosition;
+        
+        //rewrite the table pointer now that we know where the table ends
+        message.BitPosition = PointerLocation;
+        message.WriteUInt16((UInt16)(tablePosition-PointerLocation));
+
+        //write the table
+        message.BitPosition = tablePosition;
+        message.WriteUInt16((UInt16)segments.Count);
+        foreach (var segment in segments)
+        {
+            message.WriteNetSerializableStruct(segment);
+        }
+    }
+}
+
+readonly ref struct SegmentTableReader<T> where T : struct
+{
+    private class SegmentReadMsg : IReadMessage
+    {
+        private readonly IReadMessage underlyingMsg;
+        private readonly IReadOnlyList<Segment<T>> segments;
+        private readonly int segmentIndex;
+        private readonly int offset;
+        private readonly int lengthBits;
+        public SegmentReadMsg(IReadMessage underlyingMsg, IReadOnlyList<Segment<T>> segments, int segmentIndex, int offset, int lengthBits)
+        {
+            this.underlyingMsg = underlyingMsg;
+            this.segments = segments;
+            this.segmentIndex = segmentIndex;
+            this.offset = offset;
+            this.lengthBits = lengthBits;
+
+            if (offset + lengthBits >= underlyingMsg.LengthBits)
+            {
+                throw new Exception(
+                    $"Segment table is corrupt, segment length is invalid: {offset} + {lengthBits} >= {underlyingMsg.LengthBits}");
+            }
+        }
+
+        private void Check()
+        {
+            if (BitPosition > lengthBits)
+            {
+                throw new Exception($"Tried to read too much data from segment.");
+            }
+        }
+        
+        private TRead Check<TRead>(TRead v)
+        {
+            Check();
+            return v;
+        }
+
+        public bool ReadBoolean() => Check(underlyingMsg.ReadBoolean());
+
+        public void ReadPadBits()
+        {
+            Check(); underlyingMsg.ReadPadBits();
+        }
+
+        public byte ReadByte() => Check(underlyingMsg.ReadByte());
+
+        public byte PeekByte() => Check(underlyingMsg.PeekByte());
+
+        public ushort ReadUInt16() => Check(underlyingMsg.ReadUInt16());
+
+        public short ReadInt16() => Check(underlyingMsg.ReadInt16());
+
+        public uint ReadUInt32() => Check(underlyingMsg.ReadUInt32());
+
+        public int ReadInt32() => Check(underlyingMsg.ReadInt32());
+
+        public ulong ReadUInt64() => Check(underlyingMsg.ReadUInt64());
+
+        public long ReadInt64() => Check(underlyingMsg.ReadInt64());
+
+        public float ReadSingle() => Check(underlyingMsg.ReadSingle());
+
+        public double ReadDouble() => Check(underlyingMsg.ReadDouble());
+
+        public uint ReadVariableUInt32() => Check(underlyingMsg.ReadVariableUInt32());
+
+        public string ReadString() => Check(underlyingMsg.ReadString());
+
+        public Identifier ReadIdentifier() => Check(underlyingMsg.ReadIdentifier());
+
+        public Color ReadColorR8G8B8() => Check(underlyingMsg.ReadColorR8G8B8());
+
+        public Color ReadColorR8G8B8A8() => Check(underlyingMsg.ReadColorR8G8B8A8());
+
+        public int ReadRangedInteger(int min, int max) => Check(underlyingMsg.ReadRangedInteger(min, max));
+
+        public float ReadRangedSingle(float min, float max, int bitCount) => Check(underlyingMsg.ReadRangedSingle(min, max, bitCount));
+
+        public byte[] ReadBytes(int numberOfBytes) => Check(underlyingMsg.ReadBytes(numberOfBytes));
+
+        public int BitPosition
+        {
+            get => underlyingMsg.BitPosition - offset;
+            set => Check(underlyingMsg.BitPosition = value + offset);
+        }
+
+        public int BytePosition => BitPosition / 8;
+
+        public byte[] Buffer => underlyingMsg.Buffer;
+
+        public int LengthBits
+        {
+            get => lengthBits;
+            set => throw new InvalidOperationException($"Cannot resize {nameof(SegmentReadMsg)}");
+        }
+
+        public int LengthBytes => lengthBits / 8;
+
+        public NetworkConnection Sender => underlyingMsg.Sender;
+    }
+    
+    private readonly IReadMessage message;
+    private readonly List<Segment<T>> segments;
+    private readonly int exitLocation;
+    public readonly int PointerLocation;
+    private SegmentTableReader(IReadMessage message, List<Segment<T>> segments, int pointerLocation, int exitLocation)
+    {
+        this.message = message;
+        this.segments = segments;
+        this.PointerLocation = pointerLocation;
+        this.exitLocation = exitLocation;
+    }
+    
+    public IReadOnlyList<Segment<T>> Segments => segments;
+
+    public enum BreakSegmentReading
+    {
+        No,
+        Yes
+    }
+
+    public delegate BreakSegmentReading SegmentDataReader(
+        T segmentHeader,
+        IReadMessage incMsg);
+    
+    public delegate void ExceptionHandler(
+        Segment<T> segmentWithError,
+        Segment<T>[] previousSegments,
+        Exception exceptionThrown);
+    
+    public static void Read(
+        IReadMessage msg,
+        SegmentDataReader segmentDataReader,
+        ExceptionHandler? exceptionHandler = null)
+    {
+        int pointerLocation = msg.BitPosition;
+        int tablePointer = msg.ReadUInt16();
+        int tableLocation = pointerLocation + tablePointer;
+
+        int returnPosition = msg.BitPosition;
+
+        //read the table
+        var segments = new List<Segment<T>>();
+        msg.BitPosition = tableLocation;
+        int numSegments = msg.ReadUInt16();
+        for (int i = 0; i < numSegments; i++)
+        {
+            segments.Add(INetSerializableStruct.Read<Segment<T>>(msg));
+        }
+
+        //store the exit location and go back to the top
+        int exitLocation = msg.BitPosition;
+        msg.BitPosition = returnPosition;
+        using var segmentTable = new SegmentTableReader<T>(msg, segments, pointerLocation, exitLocation);
+
+        for (int i = 0; i < segmentTable.Segments.Count; i++)
+        {
+            var segment = segmentTable.Segments[i];
+            msg.BitPosition = segmentTable.PointerLocation + segment.Pointer;
+            try
+            {
+                if (segmentDataReader(segment.Identifier, new SegmentReadMsg(
+                        msg,
+                        segments,
+                        i,
+                        offset: segmentTable.PointerLocation + segment.Pointer,
+                        lengthBits: (i < segmentTable.Segments.Count - 1 ? segments[i + 1].Pointer : tablePointer) -
+                                    segment.Pointer))
+                    is BreakSegmentReading.Yes)
+                {
+                    break;
+                }
+            }
+            catch (Exception e)
+            {
+                var prevSegments = segments.Take(i).ToArray();
+                if (exceptionHandler is not null)
+                {
+                    exceptionHandler(segment, prevSegments, e);
+                }
+                else
+                {
+                    throw new Exception(
+                        $"Exception thrown while reading segment {segment.Identifier} at position {segment.Pointer}." +
+                        (prevSegments.Any() ? $" Previous segments: {string.Join(", ", prevSegments)}." : ""),
+                        e);
+                }
+            }
+        }
+    }
+
+    public void Dispose()
+    {
+        message.BitPosition = exitLocation;
+    }
+}