From 256e174e081e3ed236c6f1ee2cfba829e54a6ed9 Mon Sep 17 00:00:00 2001
From: Mira <56395159+TheXorog@users.noreply.github.com>
Date: Thu, 22 Feb 2024 12:47:08 +0100
Subject: [PATCH] fix: Properly handle relative uris + depth limit

---
 Tools/WebTools.cs | 26 +++++++++++++++++++-------
 1 file changed, 19 insertions(+), 7 deletions(-)

diff --git a/Tools/WebTools.cs b/Tools/WebTools.cs
index 4135731..9901ed0 100644
--- a/Tools/WebTools.cs
+++ b/Tools/WebTools.cs
@@ -7,18 +7,22 @@ public static class WebTools
     /// </summary>
     /// <param name="url">The shortened URL</param>
     /// <returns>The URL the redirect leads to</returns>
-    public static async Task<string> UnshortenUrl(string url, bool UseHeadMethod = true)
+    public static async Task<string> UnshortenUrl(string url, bool UseHeadMethod = true, int depth = 0, int maxDepth = 30)
     {
+        if (depth > maxDepth)
+        {
+            throw new DepthLimitReachedException();
+        }
+
         _logger?.LogDebug("Unshortening Url '{Url}', using head method: {UseHeadMethod}", url, UseHeadMethod);
 
         HttpClient client = new(new HttpClientHandler()
         {
             AllowAutoRedirect = false,
             AutomaticDecompression = DecompressionMethods.GZip,
-
         });
         client.Timeout = TimeSpan.FromSeconds(60);
-        client.DefaultRequestHeaders.UserAgent.ParseAdd("Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/98.0.4758.82 Safari/537.36");
+        client.DefaultRequestHeaders.UserAgent.ParseAdd("Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/122.0.0.0 Safari/537.36");
         client.DefaultRequestHeaders.Add("upgrade-insecure-requests", "1");
         client.DefaultRequestHeaders.Add("accept-encoding", "gzip, deflate, br");
         client.DefaultRequestHeaders.Add("accept-language", "en-US,en;q=0.9");
@@ -36,7 +40,7 @@ public static class WebTools
         catch (Exception)
         {
             if (UseHeadMethod)
-                return await UnshortenUrl(url, false);
+                return await UnshortenUrl(url, false, depth + 1, maxDepth);
 
             throw;
         }
@@ -47,7 +51,7 @@ public static class WebTools
         if (UseHeadMethod && request_task.IsFaulted && request_task.Exception.InnerException.GetType() == typeof(HttpRequestException))
         {
             _logger?.LogWarning("Unshortening Url '{Url}' failed, falling back to non-head method", url);
-            return await UnshortenUrl(url, false);
+            return await UnshortenUrl(url, false, depth + 1, maxDepth);
         }
 
         var statuscode = request_task.Result.StatusCode;
@@ -56,7 +60,7 @@ public static class WebTools
         if (UseHeadMethod && statuscode is HttpStatusCode.NotFound or HttpStatusCode.InternalServerError)
         {
             _logger?.LogWarning("Unshortening Url '{Url}' failed, falling back to non-head method", url);
-            return await UnshortenUrl(url, false);
+            return await UnshortenUrl(url, false, depth + 1, maxDepth);
         }
 
         if (statuscode is HttpStatusCode.Found
@@ -68,7 +72,13 @@ public static class WebTools
             or HttpStatusCode.TemporaryRedirect)
         {
             if (header is not null && header.Location is not null)
-                return await UnshortenUrl(header.Location.AbsoluteUri);
+            {
+
+                if (header.Location.IsAbsoluteUri)
+                    return await UnshortenUrl(header.Location.AbsoluteUri, UseHeadMethod, depth + 1, maxDepth);
+                else
+                    return await UnshortenUrl(new Uri(requestMessage.RequestUri.GetLeftPart(UriPartial.Authority).ToString() + header.Location.ToString()).AbsoluteUri, UseHeadMethod, depth + 1, maxDepth);
+            }
             else
                 return url;
         }
@@ -76,3 +86,5 @@ public static class WebTools
             return url;
     }
 }
+
+public class DepthLimitReachedException : Exception { }
\ No newline at end of file