From 9352a243744d5d6805f80dc57792919f15ca5b90 Mon Sep 17 00:00:00 2001
From: SeaEagle1 <seaeagle1@users.sourceforge.net>
Date: Fri, 12 May 2023 17:53:27 +0200
Subject: [PATCH 1/2] Rescue PlayTo function in case of malformed Xml response
 (port from 10.8 fix)

---
 Emby.Dlna/PlayTo/DlnaHttpClient.cs | 31 +++++++++++++++++++++++++-----
 1 file changed, 26 insertions(+), 5 deletions(-)

diff --git a/Emby.Dlna/PlayTo/DlnaHttpClient.cs b/Emby.Dlna/PlayTo/DlnaHttpClient.cs
index 75ff542dd8..9930f0ede1 100644
--- a/Emby.Dlna/PlayTo/DlnaHttpClient.cs
+++ b/Emby.Dlna/PlayTo/DlnaHttpClient.cs
@@ -2,9 +2,11 @@
 
 using System;
 using System.Globalization;
+using System.IO;
 using System.Net.Http;
 using System.Net.Mime;
 using System.Text;
+using System.Text.RegularExpressions;
 using System.Threading;
 using System.Threading.Tasks;
 using System.Xml;
@@ -54,15 +56,34 @@ namespace Emby.Dlna.PlayTo
                     LoadOptions.None,
                     cancellationToken).ConfigureAwait(false);
             }
-            catch (XmlException ex)
+            catch (XmlException)
             {
-                _logger.LogError(ex, "Failed to parse response");
-                if (_logger.IsEnabled(LogLevel.Debug))
+                // try correcting the Xml response with common errors
+                var xmlString = await response.Content.ReadAsStringAsync(cancellationToken).ConfigureAwait(false);
+
+                // find and replace unescaped ampersands (&)
+                Regex regex = new Regex(@"(&(?![a-z]*;))");
+                xmlString = regex.Replace(xmlString, @"&amp;");
+
+                try
                 {
-                    _logger.LogDebug("Malformed response: {Content}\n", await response.Content.ReadAsStringAsync(cancellationToken).ConfigureAwait(false));
+                    // retry reading Xml
+                    var xmlReader = new StringReader(xmlString);
+                    return await XDocument.LoadAsync(
+                        xmlReader,
+                        LoadOptions.None,
+                        cancellationToken).ConfigureAwait(false);
                 }
+                catch (XmlException ex)
+                {
+                    _logger.LogError(ex, "Failed to parse response");
+                    if (_logger.IsEnabled(LogLevel.Debug))
+                    {
+                        _logger.LogDebug("Malformed response: {Content}\n", xmlString);
+                    }
 
-                return null;
+                    return null;
+                }
             }
         }
 

From 126047bfd6fbb3156c07905b8cf58506cde2c664 Mon Sep 17 00:00:00 2001
From: SeaEagle1 <seaeagle1@users.sourceforge.net>
Date: Sat, 13 May 2023 00:07:20 +0200
Subject: [PATCH 2/2] Use compile-time generated regex and remove loglevel
 check

---
 Emby.Dlna/PlayTo/DlnaHttpClient.cs | 20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/Emby.Dlna/PlayTo/DlnaHttpClient.cs b/Emby.Dlna/PlayTo/DlnaHttpClient.cs
index 9930f0ede1..4e9903f26a 100644
--- a/Emby.Dlna/PlayTo/DlnaHttpClient.cs
+++ b/Emby.Dlna/PlayTo/DlnaHttpClient.cs
@@ -17,7 +17,10 @@ using Microsoft.Extensions.Logging;
 
 namespace Emby.Dlna.PlayTo
 {
-    public class DlnaHttpClient
+    /// <summary>
+    /// Http client for Dlna PlayTo function.
+    /// </summary>
+    public partial class DlnaHttpClient
     {
         private readonly ILogger _logger;
         private readonly IHttpClientFactory _httpClientFactory;
@@ -62,8 +65,7 @@ namespace Emby.Dlna.PlayTo
                 var xmlString = await response.Content.ReadAsStringAsync(cancellationToken).ConfigureAwait(false);
 
                 // find and replace unescaped ampersands (&)
-                Regex regex = new Regex(@"(&(?![a-z]*;))");
-                xmlString = regex.Replace(xmlString, @"&amp;");
+                xmlString = EscapeAmpersandRegex().Replace(xmlString, "&amp;");
 
                 try
                 {
@@ -77,10 +79,7 @@ namespace Emby.Dlna.PlayTo
                 catch (XmlException ex)
                 {
                     _logger.LogError(ex, "Failed to parse response");
-                    if (_logger.IsEnabled(LogLevel.Debug))
-                    {
-                        _logger.LogDebug("Malformed response: {Content}\n", xmlString);
-                    }
+                    _logger.LogDebug("Malformed response: {Content}\n", xmlString);
 
                     return null;
                 }
@@ -125,5 +124,12 @@ namespace Emby.Dlna.PlayTo
             // Have to await here instead of returning the Task directly, otherwise request would be disposed too soon
             return await SendRequestAsync(request, cancellationToken).ConfigureAwait(false);
         }
+
+        /// <summary>
+        /// Compile-time generated regular expression for escaping ampersands.
+        /// </summary>
+        /// <returns>Compiled regular expression.</returns>
+        [GeneratedRegex("(&(?![a-z]*;))")]
+        private static partial Regex EscapeAmpersandRegex();
     }
 }