[Hosts] Handle maximum of 9 hosts per entry (#26862)

* handle maximum of 9 hosts per entry

* splitted entries teaching tip

* fix entry

* message changed

src/modules/Hosts/Hosts.Tests/EntryTest.cs

@@ -75,6 +75,7 @@ namespace Hosts.Tests
         [DataRow("  host  10.1.1.1")]
         [DataRow("host 10.1.1.1")]
         [DataRow("# comment 10.1.1.1 host # comment")]
+        [DataRow("10.1.1.1 host01 host02 host03 host04 host05 host06 host07 host08 host09 host10")]
         public void Not_Valid_Entry(string line)
         {
             var entry = new Entry(0, line);

src/modules/Hosts/Hosts.Tests/HostsServiceTest.cs

@@ -69,9 +69,10 @@ namespace Hosts.Tests
             var service = new HostsService(fileSystem, userSettings.Object, _elevationHelper.Object);
             fileSystem.AddFile(service.HostsFilePath, new MockFileData(content));
 
-            var (_, entries) = await service.ReadAsync();
+            var data = await service.ReadAsync();
+            var entries = data.Entries.ToList();
             entries.Add(new Entry(0, "10.1.1.30", "host30 host30.local", "new entry", false));
-            await service.WriteAsync(string.Empty, entries);
+            await service.WriteAsync(data.AdditionalLines, entries);
 
             var result = fileSystem.GetFile(service.HostsFilePath);
             Assert.AreEqual(result.TextContents, contentResult);
@@ -94,9 +95,10 @@ namespace Hosts.Tests
             var service = new HostsService(fileSystem, userSettings.Object, _elevationHelper.Object);
             fileSystem.AddFile(service.HostsFilePath, new MockFileData(content));
 
-            var (_, entries) = await service.ReadAsync();
+            var data = await service.ReadAsync();
+            var entries = data.Entries.ToList();
             entries.RemoveAt(0);
-            await service.WriteAsync(string.Empty, entries);
+            await service.WriteAsync(data.AdditionalLines, entries);
 
             var result = fileSystem.GetFile(service.HostsFilePath);
             Assert.AreEqual(result.TextContents, contentResult);
@@ -120,13 +122,13 @@ namespace Hosts.Tests
             var service = new HostsService(fileSystem, userSettings.Object, _elevationHelper.Object);
             fileSystem.AddFile(service.HostsFilePath, new MockFileData(content));
 
-            var (_, entries) = await service.ReadAsync();
+            var data = await service.ReadAsync();
-            var entry = entries[0];
+            var entry = data.Entries[0];
             entry.Address = "10.1.1.10";
             entry.Hosts = "host host.local host1.local";
             entry.Comment = "updated comment";
             entry.Active = false;
-            await service.WriteAsync(string.Empty, entries);
+            await service.WriteAsync(data.AdditionalLines, data.Entries);
 
             var result = fileSystem.GetFile(service.HostsFilePath);
             Assert.AreEqual(result.TextContents, contentResult);
@@ -172,8 +174,8 @@ namespace Hosts.Tests
             var service = new HostsService(fileSystem, userSettings.Object, _elevationHelper.Object);
             fileSystem.AddFile(service.HostsFilePath, new MockFileData(content));
 
-            var (additionalLines, entries) = await service.ReadAsync();
+            var data = await service.ReadAsync();
-            await service.WriteAsync(additionalLines, entries);
+            await service.WriteAsync(data.AdditionalLines, data.Entries);
 
             var result = fileSystem.GetFile(service.HostsFilePath);
             Assert.AreEqual(result.TextContents, contentResult);
@@ -205,8 +207,33 @@ namespace Hosts.Tests
             var service = new HostsService(fileSystem, userSettings.Object, _elevationHelper.Object);
             fileSystem.AddFile(service.HostsFilePath, new MockFileData(content));
 
-            var (additionalLines, entries) = await service.ReadAsync();
+            var data = await service.ReadAsync();
-            await service.WriteAsync(additionalLines, entries);
+            await service.WriteAsync(data.AdditionalLines, data.Entries);
+
+            var result = fileSystem.GetFile(service.HostsFilePath);
+            Assert.AreEqual(result.TextContents, contentResult);
+        }
+
+        [TestMethod]
+        public async Task LongHosts_Splitted()
+        {
+            var content =
+@"10.1.1.1 host01 host02 host03 host04 host05 host06 host07 host08 host09 host10 host11 host12 host13 host14 host15 host16 host17 host18 host19 # comment
+";
+
+            var contentResult =
+@"10.1.1.1 host01 host02 host03 host04 host05 host06 host07 host08 host09 # comment
+10.1.1.1 host10 host11 host12 host13 host14 host15 host16 host17 host18 # comment
+10.1.1.1 host19                                                         # comment
+";
+
+            var fileSystem = new CustomMockFileSystem();
+            var userSettings = new Mock<IUserSettings>();
+            var service = new HostsService(fileSystem, userSettings.Object, _elevationHelper.Object);
+            fileSystem.AddFile(service.HostsFilePath, new MockFileData(content));
+
+            var data = await service.ReadAsync();
+            await service.WriteAsync(data.AdditionalLines, data.Entries);
 
             var result = fileSystem.GetFile(service.HostsFilePath);
             Assert.AreEqual(result.TextContents, contentResult);

src/modules/Hosts/Hosts/Consts.cs

@@ -0,0 +1,14 @@
+// Copyright (c) Microsoft Corporation
+// The Microsoft Corporation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+namespace Hosts
+{
+    public static class Consts
+    {
+        /// <summary>
+        /// Maximum number of hosts detected by the system in a single line
+        /// </summary>
+        public const int MaxHostsCount = 9;
+    }
+}

src/modules/Hosts/Hosts/Helpers/HostsService.cs

@@ -64,18 +64,21 @@ namespace Hosts.Helpers
             return _fileSystem.File.Exists(HostsFilePath);
         }
 
-        public async Task<(string Unparsed, List<Entry> Entries)> ReadAsync()
+        public async Task<HostsData> ReadAsync()
         {
             var entries = new List<Entry>();
             var unparsedBuilder = new StringBuilder();
+            var splittedEntries = false;
 
             if (!Exists())
             {
-                return (unparsedBuilder.ToString(), entries);
+                return new HostsData(entries, unparsedBuilder.ToString(), false);
             }
 
             var lines = await _fileSystem.File.ReadAllLinesAsync(HostsFilePath, Encoding);
 
+            var id = 0;
+
             for (var i = 0; i < lines.Length; i++)
             {
                 var line = lines[i];
@@ -85,11 +88,25 @@ namespace Hosts.Helpers
                     continue;
                 }
 
-                var entry = new Entry(i, line);
+                var entry = new Entry(id, line);
 
                 if (entry.Valid)
                 {
                     entries.Add(entry);
+                    id++;
+                }
+                else if (entry.Validate(false))
+                {
+                    foreach (var hostsChunk in entry.SplittedHosts.Chunk(Consts.MaxHostsCount))
+                    {
+                        var clonedEntry = entry.Clone();
+                        clonedEntry.Id = id;
+                        clonedEntry.Hosts = string.Join(' ', hostsChunk);
+                        entries.Add(clonedEntry);
+                        id++;
+                    }
+
+                    splittedEntries = true;
                 }
                 else
                 {
@@ -102,7 +119,7 @@ namespace Hosts.Helpers
                 }
             }
 
-            return (unparsedBuilder.ToString(), entries);
+            return new HostsData(entries, unparsedBuilder.ToString(), splittedEntries);
         }
 
         public async Task<bool> WriteAsync(string additionalLines, IEnumerable<Entry> entries)

src/modules/Hosts/Hosts/Helpers/IHostsService.cs

@@ -15,7 +15,7 @@ namespace Hosts.Helpers
 
         event EventHandler FileChanged;
 
-        Task<(string Unparsed, List<Entry> Entries)> ReadAsync();
+        Task<HostsData> ReadAsync();
 
         Task<bool> WriteAsync(string additionalLines, IEnumerable<Entry> entries);
 

src/modules/Hosts/Hosts/Helpers/ValidationHelper.cs

@@ -2,6 +2,7 @@
 // The Microsoft Corporation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+using System;
 using System.Text.RegularExpressions;
 
 namespace Hosts.Helpers
@@ -39,16 +40,23 @@ namespace Hosts.Helpers
         /// <summary>
         /// Determines whether the hosts are valid
         /// </summary>
-        public static bool ValidHosts(string hosts)
+        public static bool ValidHosts(string hosts, bool validateHostsLength)
         {
             if (string.IsNullOrWhiteSpace(hosts))
             {
                 return false;
             }
 
-            foreach (var host in hosts.Split(' '))
+            var splittedHosts = hosts.Split(' ');
+
+            if (validateHostsLength && splittedHosts.Length > Consts.MaxHostsCount)
             {
-                if (System.Uri.CheckHostName(host) == System.UriHostNameType.Unknown)
+                return false;
+            }
+
+            foreach (var host in splittedHosts)
+            {
+                if (Uri.CheckHostName(host) == UriHostNameType.Unknown)
                 {
                     return false;
                 }

src/modules/Hosts/Hosts/Models/Entry.cs

@@ -58,7 +58,7 @@ namespace Hosts.Models
         [ObservableProperty]
         private bool _duplicate;
 
-        public bool Valid => ValidationHelper.ValidHosts(Hosts) && Type != AddressType.Invalid;
+        public bool Valid => Validate(true);
 
         public string Line { get; private set; }
 
@@ -150,5 +150,10 @@ namespace Hosts.Models
                 Active = Active,
             };
         }
+
+        public bool Validate(bool validateHostsLength)
+        {
+            return Type != AddressType.Invalid && ValidationHelper.ValidHosts(Hosts, validateHostsLength);
+        }
     }
 }

src/modules/Hosts/Hosts/Models/HostsData.cs

@@ -0,0 +1,37 @@
+// Copyright (c) Microsoft Corporation
+// The Microsoft Corporation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System.Collections.Generic;
+using System.Collections.ObjectModel;
+
+namespace Hosts.Models
+{
+    /// <summary>
+    /// Represents the parsed hosts file
+    /// </summary>
+    public class HostsData
+    {
+        /// <summary>
+        /// Gets the parsed entries
+        /// </summary>
+        public ReadOnlyCollection<Entry> Entries { get; }
+
+        /// <summary>
+        /// Gets the lines that couldn't be parsed
+        /// </summary>
+        public string AdditionalLines { get; }
+
+        /// <summary>
+        /// Gets a value indicating whether some entries been splitted
+        /// </summary>
+        public bool SplittedEntries { get; }
+
+        public HostsData(List<Entry> entries, string additionalLines, bool splittedEntries)
+        {
+            Entries = entries.AsReadOnly();
+            AdditionalLines = additionalLines;
+            SplittedEntries = splittedEntries;
+        }
+    }
+}

src/modules/Hosts/Hosts/Strings/en-us/Resources.resw

@@ -231,7 +231,7 @@
     <comment>"Hosts" refers to the system hosts file, do not loc</comment>
   </data>
   <data name="Hosts.[using:Microsoft.UI.Xaml.Controls]ToolTipService.ToolTip" xml:space="preserve">
-    <value>Seperate multiple hosts by space (e.g. server server.local).</value>
+    <value>Seperate multiple hosts by space (e.g. server server.local). Maximum 9 hosts per entry.</value>
     <comment>Do not localize "server" and "server.local"</comment>
   </data>
   <data name="HostsFilter.Header" xml:space="preserve">
@@ -272,6 +272,17 @@
   <data name="ShowOnlyDuplicates.Header" xml:space="preserve">
     <value>Show only duplicates</value>
   </data>
+  <data name="TooManyHostsTeachingTip.Subtitle" xml:space="preserve">
+    <value>Only 9 hosts per entry are supported</value>
+    <comment>"Hosts" refers to the system hosts file, do not loc</comment>
+  </data>
+  <data name="TooManyHostsTeachingTip.Title" xml:space="preserve">
+    <value>Entries with too many hosts found</value>
+    <comment>"Hosts" refers to the system hosts file, do not loc</comment>
+  </data>
+  <data name="TooManyHostsTeachingTipContent.Text" xml:space="preserve">
+    <value>The affected entries have been splitted. This will take effect on next change.</value>
+  </data>
   <data name="UpdateBtn" xml:space="preserve">
     <value>Update</value>
   </data>

src/modules/Hosts/Hosts/ViewModels/MainViewModel.cs

@@ -68,6 +68,9 @@ namespace Hosts.ViewModels
         [ObservableProperty]
         private bool _showOnlyDuplicates;
 
+        [ObservableProperty]
+        private bool _showSplittedEntriesTooltip;
+
         partial void OnShowOnlyDuplicatesChanged(bool value)
         {
             ApplyFilters();
@@ -164,12 +167,13 @@ namespace Hosts.ViewModels
             Task.Run(async () =>
             {
                 _readingHosts = true;
-                var (additionalLines, entries) = await _hostsService.ReadAsync();
+                var data = await _hostsService.ReadAsync();
 
                 await _dispatcherQueue.EnqueueAsync(() =>
                 {
-                    AdditionalLines = additionalLines;
+                    ShowSplittedEntriesTooltip = data.SplittedEntries;
-                    _entries = new ObservableCollection<Entry>(entries);
+                    AdditionalLines = data.AdditionalLines;
+                    _entries = new ObservableCollection<Entry>(data.Entries);
 
                     foreach (var e in _entries)
                     {
@@ -346,12 +350,28 @@ namespace Hosts.ViewModels
                 return;
             }
 
-            var hosts = entry.SplittedHosts;
+            var duplicate = false;
 
-            var duplicate = _entries.FirstOrDefault(e => e != entry
+            /*
+             * Duplicate are based on the following criteria:
+             * Entries with the same type and at least one host in common
+             * Entries with the same type and address, except when there is only one entry with less than 9 hosts for that type and address
+             */
+            if (_entries.Any(e => e != entry
                 && e.Type == entry.Type
-                && (string.Equals(e.Address, entry.Address, StringComparison.OrdinalIgnoreCase)
+                && entry.SplittedHosts.Intersect(e.SplittedHosts, StringComparer.OrdinalIgnoreCase).Any()))
-                    || hosts.Intersect(e.SplittedHosts, StringComparer.OrdinalIgnoreCase).Any())) != null;
+            {
+                duplicate = true;
+            }
+            else if (_entries.Any(e => e != entry
+                && e.Type == entry.Type
+                && string.Equals(e.Address, entry.Address, StringComparison.OrdinalIgnoreCase)))
+            {
+                duplicate = entry.SplittedHosts.Length < Consts.MaxHostsCount
+                    && _entries.Count(e => e.Type == entry.Type
+                        && string.Equals(e.Address, entry.Address, StringComparison.OrdinalIgnoreCase)
+                        && e.SplittedHosts.Length < Consts.MaxHostsCount) > 1;
+            }
 
             _dispatcherQueue.TryEnqueue(() =>
             {

src/modules/Hosts/Hosts/Views/MainPage.xaml

@@ -435,7 +435,7 @@
                 HorizontalScrollBarVisibility="Auto"
                 HorizontalScrollMode="Auto">
                 <StackPanel
-                    MinWidth="480"
+                    Width="480"
                     Margin="0,12,0,0"
                     HorizontalAlignment="Stretch"
                     Spacing="24">
@@ -446,10 +446,22 @@
                     <TextBox
                         x:Uid="Hosts"
                         IsSpellCheckEnabled="False"
+                        AcceptsReturn="False"
+                        TextWrapping="Wrap"
+                        Height="100"
+                        ScrollViewer.IsVerticalRailEnabled="True"
+                        ScrollViewer.VerticalScrollBarVisibility="Visible"
+                        ScrollViewer.VerticalScrollMode="Enabled"
                         Text="{Binding Hosts, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" />
                     <TextBox
                         x:Uid="Comment"
-                        IsSpellCheckEnabled="False"
+                        IsSpellCheckEnabled="False" 
+                        AcceptsReturn="False"
+                        TextWrapping="Wrap"
+                        Height="100"
+                        ScrollViewer.IsVerticalRailEnabled="True"
+                        ScrollViewer.VerticalScrollBarVisibility="Visible"
+                        ScrollViewer.VerticalScrollMode="Enabled"
                         Text="{Binding Comment, Mode=TwoWay}" />
                     <ToggleSwitch
                         x:Uid="Active"
@@ -486,5 +498,20 @@
                 ScrollViewer.VerticalScrollMode="Enabled"
                 TextWrapping="Wrap" />
         </ContentDialog>
+        
+        <TeachingTip
+            x:Uid="TooManyHostsTeachingTip"
+            IsOpen="{x:Bind ViewModel.ShowSplittedEntriesTooltip, Mode=OneWay}"
+	        PreferredPlacement="Top"
+	        PlacementMargin="20">
+            <TeachingTip.IconSource>
+                <FontIconSource Glyph="&#xe946;" />
+            </TeachingTip.IconSource>
+            <TeachingTip.Content>
+                <TextBlock x:Uid="TooManyHostsTeachingTipContent"
+                           TextWrapping="Wrap"
+                           Margin="0,16,0,0" />
+            </TeachingTip.Content>
+        </TeachingTip>
     </Grid>
 </Page>