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mcmonkey4evamcmonkey4eva
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MicroWebHelper first writeup/experiment
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‎MicroWebHelper.cs

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using System;
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using System.Collections.Generic;
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using System.Linq;
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using System.Text;
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using System.IO;
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using System.Threading;
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using System.Threading.Tasks;
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using System.Net;
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using FreneticUtilities.FreneticToolkit;
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using FreneticUtilities.FreneticExtensions;
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namespace DiscordBotBase
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{
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/// <summary>Helper to generate an internal micro-website.</summary>
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public class MicroWebHelper
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{
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/// <summary>Helper to limit file paths to valid ones.</summary>
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public static AsciiMatcher FilePathLimiter = new(AsciiMatcher.LowercaseLetters + AsciiMatcher.Digits + "./_");
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/// <summary>The backing <see cref="HttpListener"/> instance.</summary>
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public HttpListener Listener;
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/// <summary>The file path for raw files, if any.</summary>
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public string RawFileRoot;
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/// <summary>The token that can cancel this web helper.</summary>
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public CancellationTokenSource CancelToken = new();
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/// <summary>Token indicates that the whole system is done.</summary>
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public CancellationTokenSource IsEnded = new ();
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/// <summary>Pre-scanned list of valid paths for the raw file root.</summary>
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public HashSet<string> RawRootStartPaths = new();
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/// <summary>Function to get dynamic pages as-needed.</summary>
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public Func<string, HttpListenerContext, WebResult> PageGetter;
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/// <summary>Matcher for values escaped by <see cref="HtmlEscape"/>.</summary>
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public static AsciiMatcher NeedsHTMLEscapeMatcher = new("&<>");
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/// <summary>Escapes a string to safely output it into HTML.</summary>
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public static string HtmlEscape(string input)
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{
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if (!NeedsHTMLEscapeMatcher.ContainsAnyMatch(input))
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{
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return input;
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}
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return input.Replace("&", "&amp;").Replace("<", "&lt;").Replace(">", "&gt;");
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}
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/// <summary>Helper class to make injectable HTML based on the &lt;%INJECT_ID%&gt; format.</summary>
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public class InjectableHtml
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{
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/// <summary>A single part of the HTML page.</summary>
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public class Component
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{
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/// <summary>If true: injectable text. If false: raw text.</summary>
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public bool DoReplace;
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/// <summary>The raw content of the component.</summary>
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public string Content;
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}
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/// <summary>The parts that make up this page.</summary>
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public List<Component> Components = new(4);
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/// <summary>An estimate of the length of this page.</summary>
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public int Length;
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/// <summary>Constructs the injectable HTML from the raw pseudo-html string.</summary>
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public InjectableHtml(string raw)
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{
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Length = raw.Length;
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int start = raw.IndexOf("<%");
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int lastEnd = 0;
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while (start != -1)
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{
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Components.Add(new Component() { DoReplace = false, Content = raw[lastEnd..start] });
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int end = raw.IndexOf("%>", start + 2);
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if (end == -1)
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{
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throw new Exception("Invalid injectable html, mismatched inject blocks");
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}
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Components.Add(new Component() { DoReplace = true, Content = raw[(start + 2)..end] });
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lastEnd = end + 2;
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start = raw.IndexOf("<%", end);
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}
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Components.Add(new Component() { DoReplace = false, Content = raw[lastEnd..] });
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}
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/// <summary>Gets the final form of the HTML, using the injecter method.</summary>
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public string Get(Func<string, string> inject)
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{
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StringBuilder output = new(Length * 2);
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foreach (Component component in Components)
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{
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output.Append(component.DoReplace ? inject(component.Content) : component.Content);
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}
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return output.ToString();
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}
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}
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/// <summary>Holds a cacheable response to a web request.</summary>
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public class WebResult
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{
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/// <summary>The default utter failure response.</summary>
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public static WebResult FAIL = new() { Code = 400, ContentType = "text/plain", Data = StringConversionHelper.UTF8Encoding.GetBytes("Server did not provide a response to the request.") };
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/// <summary>The status code, eg '200' for 'OK' or '404' for 'File Not Found'</summary>
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public int Code = 200;
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/// <summary>The content type of the response, eg 'text/html' for HTML text.</summary>
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public string ContentType = "text/plain";
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/// <summary>The raw data of the response.</summary>
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public byte[] Data;
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/// <summary>The time this result was generated per <see cref="Environment.TickCount64"/>, for cache management.</summary>
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public long GeneratedTickTime = Environment.TickCount64;
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/// <summary>Applies the cached response to a request.</summary>
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public void Apply(HttpListenerResponse response)
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{
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response.StatusCode = Code;
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response.ContentType = ContentType;
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response.ContentLength64 = Data.LongLength;
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response.OutputStream.Write(Data, 0, Data.Length);
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response.Close();
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}
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}
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/// <summary>Cache of raw root files.</summary>
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public Dictionary<string, WebResult> RawFileCache = new();
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/// <summary>Creates and immediately starts the web helper.</summary>
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public MicroWebHelper(string bind, Func<string, HttpListenerContext, WebResult> _pageGetter, string _rawFileRoot = "wwwroot/")
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{
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PageGetter = _pageGetter;
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RawFileRoot = _rawFileRoot;
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if (_rawFileRoot is not null)
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{
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RawRootStartPaths.UnionWith(Directory.GetFiles(_rawFileRoot).Select(f => f.AfterLast('/')));
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RawRootStartPaths.UnionWith(Directory.GetDirectories(_rawFileRoot).Select(f => f.AfterLast('/')));
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}
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Listener = new HttpListener();
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Listener.Prefixes.Add(bind);
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Listener.Start();
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new Thread(InternalLoop) { Name = "MicroWebHelper" }.Start();
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}
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/// <summary>Cancels the web helper. Signals web thread to close ASAP.</summary>
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public void Cancel()
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{
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CancelToken.Cancel();
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try
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{
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Task.Delay(TimeSpan.FromSeconds(5)).Wait(IsEnded.Token);
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}
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catch (OperationCanceledException)
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{
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// Ignore - expected
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}
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}
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/// <summary>A mapping of common file extensions to their content type.</summary>
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public static Dictionary<string, string> CommonContentTypes = new()
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{
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{ "png", "image/png" },
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{ "jpg", "image/jpeg" },
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{ "jpeg", "image/jpeg" },
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{ "gif", "image/gif" },
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{ "ico", "image/x-icon" },
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{ "svg", "image/svg+xml" },
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{ "mp3", "audio/mpeg" },
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{ "wav", "audio/x-wav" },
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{ "js", "application/javascript" },
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{ "ogg", "application/ogg" },
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{ "json", "application/json" },
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{ "zip", "application/zip" },
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{ "dat", "application/octet-stream" },
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{ "css", "text/css" },
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{ "htm", "text/html" },
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{ "html", "text/html" },
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{ "txt", "text/plain" },
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{ "yml", "text/plain" },
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{ "fds", "text/plain" },
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{ "xml", "text/xml" },
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{ "mp4", "video/mp4" },
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{ "mpeg", "video/mpeg" },
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{ "webm", "video/webm" }
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};
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/// <summary>Guesses the content type based on path for common file types.</summary>
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public static string GuessContentType(string path)
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{
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string extension = path.AfterLast('.');
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if (CommonContentTypes.TryGetValue(extension, out string type))
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{
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return type;
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}
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return "application/octet-stream";
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}
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/// <summary>Internal thread loop, do not reference directly.</summary>
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public void InternalLoop()
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{
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string lastUrl = "unknown";
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try
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{
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while (true)
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{
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if (CancelToken.IsCancellationRequested)
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{
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return;
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}
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try
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{
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Task<HttpListenerContext> contextGetter = Listener.GetContextAsync();
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contextGetter.Wait(CancelToken.Token);
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HttpListenerContext context = contextGetter.Result;
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string url = context.Request.Url.AbsolutePath;
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if (url.StartsWithFast('/'))
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{
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url = url[1..];
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}
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string fixedUrl = FilePathLimiter.TrimToMatches(url);
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lastUrl = fixedUrl;
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if (!fixedUrl.Contains("..") && !fixedUrl.Contains("/.") && !fixedUrl.Contains("./") && RawRootStartPaths.Contains(fixedUrl.Before('/')))
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{
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if (RawFileCache.TryGetValue(fixedUrl, out WebResult cache))
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{
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cache.Apply(context.Response);
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continue;
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}
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string filePath = RawFileRoot + fixedUrl;
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if (File.Exists(filePath))
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{
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WebResult newResult = new()
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{
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Code = 200,
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ContentType = GuessContentType(fixedUrl),
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Data = File.ReadAllBytes(filePath)
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};
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RawFileCache[fixedUrl] = newResult;
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newResult.Apply(context.Response);
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continue;
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}
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}
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WebResult result = PageGetter(fixedUrl, context);
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if (result is not null)
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{
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result.Apply(context.Response);
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continue;
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}
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WebResult.FAIL.Apply(context.Response);
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}
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catch (OperationCanceledException)
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{
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return;
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}
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catch (Exception ex)
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{
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Console.Error.WriteLine($"Web request ({lastUrl}) failed: {ex}");
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}
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}
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}
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finally
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{
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Listener.Abort();
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IsEnded.Cancel();
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}
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}
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}
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}

‎mcmonkeyDiscordBotBase.csproj

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<EmbeddedResource Include="**\*.resx" />
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</ItemGroup>
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<ItemGroup>
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<PackageReference Include="Discord.Net" Version="3.4.0" />
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<PackageReference Include="Discord.Net.WebSocket" Version="3.4.0" />
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<PackageReference Include="Discord.Net" Version="3.4.1" />
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<PackageReference Include="Discord.Net.WebSocket" Version="3.4.1" />
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</ItemGroup>
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<ItemGroup>
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<Compile Remove="FreneticUtilities\*.*" />

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