Added method in ParseUtil that strips out every invalid XML character from a string.

Added test for ParseUtil.RemoveInvalidXmlChars() using a snippet of rss from XSeeds that was originally causing problems.

src/Jackett.Test/Jackett.Test.csproj

@@ -164,6 +164,7 @@
     <Compile Include="TestIIndexerManagerServiceHelper.cs" />
     <Compile Include="TestUtil.cs" />
     <Compile Include="TestWebClient.cs" />
+    <Compile Include="Util\ParseUtilTests.cs" />
     <Compile Include="Util\ServerUtilTests.cs" />
     <Compile Include="Util\TvCategoryParserTests.cs" />
   </ItemGroup>
@@ -182,6 +183,9 @@
   <ItemGroup>
     <Folder Include="Indexers\" />
   </ItemGroup>
+  <ItemGroup>
+    <EmbeddedResource Include="Util\Invalid-RSS.xml" />
+  </ItemGroup>
   <Choose>
     <When Condition="'$(VisualStudioVersion)' == '10.0' And '$(IsCodedUITest)' == 'True'">
       <ItemGroup>

src/Jackett.Test/Util/Invalid-RSS.xml

@@ -0,0 +1,20 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<rss version="2.0">
+  <channel>
+    <title>RSS Syndicator</title>
+    <link>http://somewebsite.com</link>
+    <description>
+      &lt;br /&gt;
+      Enjoy!&lt;br /&gt;
+      &lt;br /&gt;
+      -&lt;br /&gt;
+      &lt;br /&gt;
+       group info&lt;br /&gt;
+      &lt;br /&gt;
+      Know Your Role and Shut Your Mouth!&lt;br /&gt;
+      &lt;br /&gt;
+       we are now looking for...&lt;br /&gt;
+      &lt;br /&gt;
+    </description>
+  </channel>
+</rss>

src/Jackett.Test/Util/ParseUtilTests.cs

@@ -0,0 +1,46 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using System.Xml.Linq;
+using System.Xml.XPath;
+using FluentAssertions;
+using Jackett.Utils;
+using NUnit.Framework;
+
+namespace JackettTest.Util
+{
+    [TestFixture]
+    public class ParseUtilTests
+    {
+        private static string InvalidRssXml
+        {
+            get
+            {
+                var type = typeof(ParseUtilTests);
+                using (var resourceStream = type.Assembly.GetManifestResourceStream($"{type.Namespace}.Invalid-RSS.xml"))
+                using (var sr = new StreamReader(resourceStream))
+                {
+                    return sr.ReadToEnd();
+                }
+                
+            }
+        }
+
+        [Test]
+        public void Invalid_RSS_should_parse_after_removing_invalid_chars()
+        {
+            var invalidRss = InvalidRssXml;
+            Action parseAction = () => XDocument.Parse(invalidRss);
+            parseAction.ShouldThrow<Exception>().WithMessage("'\a', hexadecimal value 0x07, is an invalid character. Line 12, position 7.");
+
+            var validRSs = ParseUtil.RemoveInvalidXmlChars(invalidRss);
+            var rssDoc = XDocument.Parse(validRSs);
+            rssDoc.Root.Should().NotBeNull();
+            var description = rssDoc.Root.XPathSelectElement("//description");
+            description.Value.Should().Contain("Know Your Role and Shut Your Mouth!");
+        }
+    }
+}

src/Jackett/Indexers/XSpeeds.cs

@@ -13,6 +13,7 @@ using System.Threading.Tasks;
 using Jackett.Models.IndexerConfig;
 using System.Text.RegularExpressions;
 using System.Xml.Linq;
+using static Jackett.Utils.ParseUtil;
 
 namespace Jackett.Indexers
 {
@@ -128,7 +129,7 @@ namespace Jackett.Indexers
                 if (rssPage.Content.EndsWith("\0")) {
                     rssPage.Content = rssPage.Content.Substring(0, rssPage.Content.Length - 1);
                 }
-                rssPage.Content = rssPage.Content.Replace("\0x10", "").Replace("\0x07", "");
+                rssPage.Content = RemoveInvalidXmlChars(rssPage.Content);
                 var rssDoc = XDocument.Parse(rssPage.Content);
 
                 foreach (var item in rssDoc.Descendants("item"))

src/Jackett/Utils/ParseUtil.cs

@@ -1,9 +1,15 @@
 using System.Globalization;
+using System.Text.RegularExpressions;
 
 namespace Jackett.Utils
 {
     public static class ParseUtil
     {
+        private static readonly Regex InvalidXmlChars =
+            new Regex(
+                @"(?<![\uD800-\uDBFF])[\uDC00-\uDFFF]|[\uD800-\uDBFF](?![\uDC00-\uDFFF])|[\x00-\x08\x0B\x0C\x0E-\x1F\x7F-\x9F\uFEFF\uFFFE\uFFFF]",
+                RegexOptions.Compiled);
+
         public static string NormalizeSpace(string s)
         {
             return s.Trim();
@@ -17,6 +23,11 @@ namespace Jackett.Utils
             return normalized;
         }
 
+        public static string RemoveInvalidXmlChars(string text)
+        {
+            return string.IsNullOrEmpty(text) ? "" : InvalidXmlChars.Replace(text, "");
+        }
+
         public static double CoerceDouble(string str)
         {
             return double.Parse(NormalizeNumber(str), NumberStyles.Any, CultureInfo.InvariantCulture);