Use pipelines to read request bodies instead of stream

ProjectLighthouse.Servers.GameServer/Controllers/Matching/MatchController.cs

@@ -48,7 +48,7 @@ public class MatchController : ControllerBase
 
         if (bodyString.Length == 0 || bodyString[0] != '[') return this.BadRequest();
 
-        Logger.Info("Received match data: " + bodyString, LogArea.Match);
+        Logger.Debug("Received match data: " + bodyString, LogArea.Match);
 
         IMatchCommand? matchData;
         try

ProjectLighthouse/Extensions/ControllerExtensions.cs

@@ -1,7 +1,10 @@
 #nullable enable
 using System;
+using System.Buffers;
 using System.IO;
+using System.IO.Pipelines;
 using System.Linq;
+using System.Text;
 using System.Text.RegularExpressions;
 using System.Threading.Tasks;
 using System.Xml.Serialization;
@@ -12,7 +15,7 @@ using Microsoft.AspNetCore.Mvc;
 
 namespace LBPUnion.ProjectLighthouse.Extensions;
 
-public static class ControllerExtensions
+public static partial class ControllerExtensions
 {
 
     public static GameToken GetToken(this ControllerBase controller)
@@ -23,25 +26,72 @@ public static class ControllerExtensions
         return token;
     }
 
+    private static void AddStringToBuilder(StringBuilder builder, in ReadOnlySequence<byte> readOnlySequence)
+    {
+        // Separate method because Span/ReadOnlySpan cannot be used in async methods
+        ReadOnlySpan<byte> span = readOnlySequence.IsSingleSegment
+            ? readOnlySequence.First.Span
+            : readOnlySequence.ToArray().AsSpan();
+        builder.Append(Encoding.UTF8.GetString(span));
+    }
+
     public static async Task<string> ReadBodyAsync(this ControllerBase controller)
     {
-        controller.Request.Body.Position = 0;
+        StringBuilder builder = new();
 
-        using StreamReader bodyReader = new(controller.Request.Body);
+        while (true)
-        return await bodyReader.ReadToEndAsync();
+        {
+            ReadResult readResult = await controller.Request.BodyReader.ReadAsync();
+            ReadOnlySequence<byte> buffer = readResult.Buffer;
+
+            SequencePosition? position;
+
+            do
+            {
+                // Look for a EOL in the buffer
+                position = buffer.PositionOf((byte)'\n');
+                if (position == null) continue;
+
+                ReadOnlySequence<byte> readOnlySequence = buffer.Slice(0, position.Value);
+                AddStringToBuilder(builder, in readOnlySequence);
+
+                // Skip the line + the \n character (basically position)
+                buffer = buffer.Slice(buffer.GetPosition(1, position.Value));
             }
+            while (position != null);
+
+
+            if (readResult.IsCompleted && buffer.Length > 0)
+            {
+                AddStringToBuilder(builder, in buffer);
+            }
+
+            controller.Request.BodyReader.AdvanceTo(buffer.Start, buffer.End);
+
+            // At this point, buffer will be updated to point one byte after the last
+            // \n character.
+            if (readResult.IsCompleted)
+            {
+                break;
+            }
+        }
+
+        return builder.ToString();
+    }
+
+    [GeneratedRegex("&(?!(amp|apos|quot|lt|gt);)")]
+    private static partial Regex CharacterEscapeRegex();
 
     public static async Task<T?> DeserializeBody<T>(this ControllerBase controller, params string[] rootElements)
     {
         controller.Request.Body.Position = 0;
 
-        using StreamReader bodyReader = new(controller.Request.Body);
+        string bodyString = await controller.ReadBodyAsync();
-        string bodyString = await bodyReader.ReadToEndAsync();
 
         try
         {
             // Prevent unescaped ampersands from causing deserialization to fail
-            bodyString = Regex.Replace(bodyString, "&(?!(amp|apos|quot|lt|gt);)", "&amp;");
+            bodyString = CharacterEscapeRegex().Replace(bodyString, "&amp;");
 
             XmlRootAttribute? root = null;
             if (rootElements.Length > 0)

ProjectLighthouse/Helpers/MatchHelper.cs

@@ -2,14 +2,13 @@
 using System;
 using System.Collections.Generic;
 using System.Diagnostics;
-using System.Linq;
 using System.Text.Json;
 using System.Text.RegularExpressions;
 using LBPUnion.ProjectLighthouse.Match.MatchCommands;
 
 namespace LBPUnion.ProjectLighthouse.Helpers;
 
-public static class MatchHelper
+public static partial class MatchHelper
 {
     public static readonly Dictionary<int, string?> UserLocations = new();
     public static readonly Dictionary<int, List<int>?> UserRecentlyDivedIn = new();
@@ -38,27 +37,23 @@ public static class MatchHelper
 
     public static bool ClearUserRecentDiveIns(int userId) => UserRecentlyDivedIn.Remove(userId);
 
+    [GeneratedRegex("^\\[([^,]*),\\[(.*)\\]\\]")]
+    private static partial Regex MatchJsonRegex();
+
+    [GeneratedRegex(@"0x[a-fA-F0-9]{7,8}")]
+    private static partial Regex LocationHexRegex();
+
     // This is the function used to show people how laughably awful LBP's protocol is. Beware.
     public static IMatchCommand? Deserialize(string data)
     {
-        string matchType = "";
+        System.Text.RegularExpressions.Match match = MatchJsonRegex().Match(data);
 
-        int i = 1;
+        string matchType = match.Groups[1].Value;
-        while (true)
+        // Wraps the actual match data in curly braces to parse it as a json object
-        {
+        string matchData = $"{{{match.Groups[2].Value}}}";
-            if (data[i] == ',') break;
-
-            matchType += data[i];
-            i++;
-        }
-
-        string matchData = $"{{{string.Concat(data.Skip(matchType.Length + 3).SkipLast(2))}}}"; // unfuck formatting so we can parse it as json
 
         // JSON does not like the hex value that location comes in (0x7f000001) so, convert it to int
-        matchData = Regex.Replace(matchData, @"0x[a-fA-F0-9]{8}", m => Convert.ToInt32(m.Value, 16).ToString());
+        matchData = LocationHexRegex().Replace(matchData, m => Convert.ToInt32(m.Value, 16).ToString());
-        // oh, but it gets better than that! LBP also likes to send hex values with an uneven amount of digits (0xa000064, 7 digits). in any case, we handle it here:
-        matchData = Regex.Replace(matchData, @"0x[a-fA-F0-9]{7}", m => Convert.ToInt32(m.Value, 16).ToString());
-        // i'm actually crying about it.
 
         return Deserialize(matchType, matchData);
     }