Exporting Ldap users to CSV for Webuntis import works now

Wollmilchsau/Components/App.razor

@@ -20,6 +20,7 @@
     <ReconnectModal />
     <script src="@Assets["_framework/blazor.web.js"]"></script>
     <script src="@Assets["_content/MudBlazor/MudBlazor.min.js"]"></script>
+    <script src="@Assets["js/file-download.js"]"></script>
 
 </body>
 

Wollmilchsau/Components/Pages/Home.razor

@@ -1,7 +1,65 @@
 @page "/"
+@inject Wollmilchsau.Services.Ldap.ILdapService LdapService
+@inject IJSRuntime JsRuntime
 
-<PageTitle>Home</PageTitle>
+<PageTitle>LDAP Users</PageTitle>
 
-<h1>Hello, world!</h1>
+<button class="btn btn-primary" @onclick="DownloadCsvAsync" disabled="@(users is null)">Export CSV</button>
 
-Welcome to your new app.
+<h1>LDAP Users</h1>
+
+@if (users is null)
+{
+    <p><em>Loading users...</em></p>
+}
+else
+{
+    <table class="table">
+        <thead>
+            <tr>
+                <th>Username</th>
+                <th>Surname</th>
+                <th>Classroom</th>
+                <th>Given name</th>
+                <th>Incomplete</th>
+            </tr>
+        </thead>
+        <tbody>
+            @foreach (var user in users)
+            {
+                <tr>
+                    <td>@user.Username</td>
+                    <td>@user.Surname</td>
+                    <td>@user.Classroom</td>
+                    <td>@user.GivenName</td>
+                    <td>@user.Incomplete</td>
+                </tr>
+            }
+        </tbody>
+    </table>
+}
+
+@code {
+    private List<Wollmilchsau.Models.LdapUser>? users;
+
+    protected override async Task OnInitializedAsync()
+    {
+        users = [];
+
+        await foreach (var user in LdapService.GetAllUsers())
+        {
+            users.Add(user);
+        }
+    }
+
+    private Task DownloadCsvAsync()
+    {
+        var csv = string.Join("\r\n", users!.Select(user => string.Join(';',
+            user.GivenName ?? string.Empty,
+            user.Surname ?? string.Empty,
+            user.Classroom ?? string.Empty,
+            user.Username)));
+
+        return JsRuntime.InvokeVoidAsync("downloadTextFile", "ldap-users.csv", csv).AsTask();
+    }
+}

Wollmilchsau/Models/LdapUser.cs

@@ -1,5 +1,8 @@
 namespace Wollmilchsau.Models;
 
-public sealed record LdapUser
-{
-}
+public sealed record LdapUser(
+    string Username,
+    string? Surname,
+    string? Classroom,
+    string? GivenName,
+    bool Incomplete);

Wollmilchsau/Program.cs

@@ -5,9 +5,16 @@ using MudBlazor.Services;
 using System.Net.Http.Headers;
 using Wollmilchsau.Components;
 using Wollmilchsau.Exceptions;
+using Wollmilchsau.Services.Ldap;
 
 var builder = WebApplication.CreateBuilder(args);
 
+builder.Services.AddOptions<LdapOptions>()
+    .BindConfiguration("LDAP")
+    .ValidateDataAnnotations()
+    .ValidateOnStart();
+builder.Services.AddScoped<ILdapService, LdapService>();
+
 // Add services to the container.
 builder.Services.AddRazorComponents()
     .AddInteractiveServerComponents();
@@ -27,7 +34,7 @@ builder.Services.AddHttpClient("matrix_synapse", client =>
 });
 builder.Services.AddStackExchangeRedisCache(options =>
 {
-    options.Configuration = builder.Configuration.GetConnectionString("cache") ?? throw new ConfigurationException("ConnectionStrings:cache");
+    options.Configuration = builder.Configuration.GetConnectionString("RedisCache") ?? throw new ConfigurationException("ConnectionStrings:RedisCache");
     options.InstanceName = "OneForAll:";
 });
 

Wollmilchsau/Services/Ldap/ILdapService.cs

@@ -0,0 +1,8 @@
+using Wollmilchsau.Models;
+
+namespace Wollmilchsau.Services.Ldap;
+
+public interface ILdapService
+{
+    IAsyncEnumerable<LdapUser> GetAllUsers(CancellationToken cancellationToken = default);
+}

Wollmilchsau/Services/Ldap/LdapOptions.cs

@@ -0,0 +1,27 @@
+using System.ComponentModel.DataAnnotations;
+
+namespace Wollmilchsau.Services.Ldap;
+
+public sealed class LdapOptions
+{
+    [Required]
+    public string LdapUri { get; init; } = string.Empty;
+
+    [Required]
+    public string BindPassword { get; init; } = string.Empty;
+
+    [Required]
+    public string BindDN { get; init; } = string.Empty;
+
+    [Required]
+    public string BaseDN { get; init; } = string.Empty;
+
+    [Required]
+    public string UserBase { get; init; } = string.Empty;
+
+    [Required]
+    public string RoleBase { get; init; } = string.Empty;
+
+    [Required]
+    public string StudentsRole { get; init; } = string.Empty;
+}

Wollmilchsau/Services/Ldap/LdapService.cs

@@ -0,0 +1,132 @@
+using System.DirectoryServices.Protocols;
+using System.Net;
+using System.Text;
+using Microsoft.Extensions.Options;
+using Wollmilchsau.Models;
+
+namespace Wollmilchsau.Services.Ldap;
+
+public sealed class LdapService(IOptions<LdapOptions> options) : ILdapService
+{
+    private readonly LdapOptions _options = options.Value;
+
+    public async IAsyncEnumerable<LdapUser> GetAllUsers(
+        [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
+    {
+        cancellationToken.ThrowIfCancellationRequested();
+
+        using var connection = CreateConnection();
+        foreach (var user in GetUsers(connection))
+        {
+            cancellationToken.ThrowIfCancellationRequested();
+            yield return user;
+            await Task.Yield();
+        }
+    }
+
+    private LdapConnection CreateConnection()
+    {
+        var ldapUri = new Uri(_options.LdapUri, UriKind.Absolute);
+        if (!string.Equals(ldapUri.Scheme, "ldap", StringComparison.OrdinalIgnoreCase) &&
+            !string.Equals(ldapUri.Scheme, "ldaps", StringComparison.OrdinalIgnoreCase))
+        {
+            throw new InvalidOperationException("LDAP:LdapUri must use the ldap or ldaps scheme.");
+        }
+
+        var connection = new LdapConnection(new LdapDirectoryIdentifier(ldapUri.Host, ldapUri.Port))
+        {
+            AuthType = AuthType.Basic,
+            Timeout = TimeSpan.FromSeconds(30)
+        };
+
+        connection.SessionOptions.ProtocolVersion = 3;
+        connection.SessionOptions.SecureSocketLayer = string.Equals(ldapUri.Scheme, "ldaps", StringComparison.OrdinalIgnoreCase);
+        connection.Bind(new NetworkCredential(_options.BindDN, _options.BindPassword));
+
+        return connection;
+    }
+
+    private IEnumerable<LdapUser> GetUsers(LdapConnection connection)
+    {
+        var studentRoleDn = BuildDistinguishedName(_options.StudentsRole, _options.RoleBase);
+        var request = new SearchRequest(
+            BuildDistinguishedName(_options.UserBase),
+            $"(memberOf={EscapeFilterValue(studentRoleDn)})",
+            SearchScope.Subtree,
+            "uid",
+            "sn",
+            "departmentNumber",
+            "givenName");
+        var response = (SearchResponse)connection.SendRequest(request);
+
+        return response.Entries
+            .Cast<SearchResultEntry>()
+            .Select(CreateUser);
+    }
+
+    private LdapUser CreateUser(SearchResultEntry entry)
+    {
+        var username = GetFirstAttributeValue(entry, "uid") ?? throw new InvalidOperationException($"LDAP user entry '{entry.DistinguishedName}' is missing uid.");
+        var surname = CapitalizeFirstLetter(GetFirstAttributeValue(entry, "sn"));
+        var classroom = GetFirstAttributeValue(entry, "departmentNumber");
+        var givenName = GetFirstAttributeValue(entry, "givenName");
+
+        return new LdapUser(
+            username,
+            surname,
+            classroom,
+            givenName,
+            string.IsNullOrWhiteSpace(surname) ||
+            string.IsNullOrWhiteSpace(classroom) ||
+            string.IsNullOrWhiteSpace(givenName));
+    }
+
+    private string BuildDistinguishedName(params string[] relativeNames)
+    {
+        return string.Join(',', relativeNames.Append(_options.BaseDN));
+    }
+
+    private static IEnumerable<string> GetAttributeValues(SearchResultEntry entry, string attributeName)
+    {
+        if (!entry.Attributes.Contains(attributeName))
+        {
+            return [];
+        }
+
+        return entry.Attributes[attributeName]
+            .GetValues(typeof(string))
+            .OfType<string>();
+    }
+
+    private static string? GetFirstAttributeValue(SearchResultEntry entry, string attributeName)
+    {
+        return GetAttributeValues(entry, attributeName).FirstOrDefault();
+    }
+
+    private static string? CapitalizeFirstLetter(string? value)
+    {
+        return string.IsNullOrWhiteSpace(value)
+            ? value
+            : char.ToUpperInvariant(value[0]) + value[1..];
+    }
+
+    private static string EscapeFilterValue(string value)
+    {
+        var builder = new StringBuilder();
+
+        foreach (var valueByte in Encoding.UTF8.GetBytes(value))
+        {
+            if (valueByte is >= 0x20 and <= 0x7e and not (byte)'*' and not (byte)'(' and not (byte)')' and not (byte)'\\')
+            {
+                builder.Append((char)valueByte);
+            }
+            else
+            {
+                builder.Append('\\');
+                builder.Append(valueByte.ToString("X2"));
+            }
+        }
+
+        return builder.ToString();
+    }
+}

Wollmilchsau/appsettings.Development.json

@@ -50,14 +50,14 @@
     "LdapUri": "ldaps://bs18-hh.de:10636",
     "BindPassword": "skMXHFyf3fjW4iJhsoEyfQdc0wYthuVs6xim7BKhX3c5EZSuPcRrYYiGonynBnHW",
     "BindDN": "cn=bs18ldap,ou=ldap,dc=bs18-hh,dc=de",
-    "BaseDN": "ou=dc=bs18-hh,dc=de",
+    "BaseDN": "dc=bs18-hh,dc=de",
     "UserBase": "ou=users",
     "RoleBase": "ou=roles",
     "GroupBase": "ou=groups",
-    "PupilRole": "CN=ROLE_STUDENT",
+    "StudentsRole": "CN=ROLE_STUDENT",
     "TeacherRole": "CN=ROLE_TEACHER",
     "AdminRole": "CN=ROLE_ADMIN",
-    "KlassgroupFilter": "(cn=klasse.*)",
+    "KlasseGroupFilter": "(cn=klasse.*)",
     "UserFilter": "(uid=*)"
   }
 }

Wollmilchsau/wwwroot/js/file-download.js

@@ -0,0 +1,11 @@
+window.downloadTextFile = (fileName, content) => {
+    const blob = new Blob([content], { type: "text/csv;charset=utf-8" });
+    const url = URL.createObjectURL(blob);
+    const anchor = document.createElement("a");
+
+    anchor.href = url;
+    anchor.download = fileName;
+    anchor.click();
+
+    URL.revokeObjectURL(url);
+};