Joseph Doherty
113 lines
3.7 KiB
Plaintext
113 lines
3.7 KiB
Plaintext
@implements IDisposable
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@inject NavigationManager Navigation
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@inject IJSRuntime JS
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<AntiforgeryToken />
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@code {
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// Passive HTTP probes observe expiry but never advance activity. The JS module
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// separately reports trusted browser input through an antiforgery-protected POST.
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/// <summary>Server endpoint that reports live session validity.</summary>
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internal const string PingUrl = "/auth/ping";
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/// <summary>HTTP status returned by <see cref="PingUrl"/> once the cookie has lapsed.</summary>
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private const int Unauthorized = 401;
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private const string ModulePath = "./_content/ZB.MOM.WW.ScadaBridge.CentralUI/js/session-expiry.js";
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/// <summary>How often the session validity is re-checked.</summary>
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internal static readonly TimeSpan PollInterval = TimeSpan.FromMinutes(1);
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private CancellationTokenSource? _cts;
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private IJSObjectReference? _module;
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protected override void OnInitialized()
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{
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// The login page uses the same layout, so this component renders there
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// too. Polling/redirecting on /login → /login would loop.
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if (IsOnLoginPage) return;
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_cts = new CancellationTokenSource();
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_ = PollSessionAsync(_cts.Token);
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}
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protected override async Task OnAfterRenderAsync(bool firstRender)
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{
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if (!firstRender || IsOnLoginPage) return;
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try { _module ??= await JS.InvokeAsync<IJSObjectReference>("import", ModulePath); }
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catch (JSDisconnectedException) { }
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catch (JSException) { }
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}
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private bool IsOnLoginPage =>
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Navigation.ToBaseRelativePath(Navigation.Uri)
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.StartsWith("login", StringComparison.OrdinalIgnoreCase);
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private async Task PollSessionAsync(CancellationToken token)
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{
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while (!token.IsCancellationRequested)
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{
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try { await Task.Delay(PollInterval, token); }
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catch (TaskCanceledException) { return; }
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if (token.IsCancellationRequested) return;
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await CheckSessionAsync();
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}
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}
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/// <summary>
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/// Runs one liveness check: pings the server and, if the session has lapsed
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/// server-side (HTTP 401), redirects to the login page. Exposed for tests
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/// (CentralUI-025) so the redirect path can be exercised without waiting on
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/// the poll interval.
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/// </summary>
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internal async Task CheckSessionAsync()
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{
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if (IsOnLoginPage) return;
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int status;
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try
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{
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_module ??= await JS.InvokeAsync<IJSObjectReference>("import", ModulePath);
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status = await _module.InvokeAsync<int>("ping", PingUrl);
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}
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catch (JSDisconnectedException)
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{
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// Circuit gone — nothing to redirect.
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return;
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}
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catch (JSException)
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{
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// Network blip or fetch failure: treat as inconclusive and retry on
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// the next poll rather than logging an authenticated user out on a
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// transient error.
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return;
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}
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if (status == Unauthorized)
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{
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await InvokeAsync(() => Navigation.NavigateTo("/login", forceLoad: true));
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}
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}
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public void Dispose()
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{
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_cts?.Cancel();
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_cts?.Dispose();
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// The module reference is owned by the circuit's JS runtime; once the
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// circuit is disposed disposing it would throw — fire-and-forget and
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// swallow the expected disconnect.
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if (_module is not null)
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{
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_ = DisposeModuleAsync(_module);
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}
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}
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private static async Task DisposeModuleAsync(IJSObjectReference module)
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{
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try { await module.DisposeAsync(); }
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catch (JSDisconnectedException) { /* circuit already gone */ }
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}
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}
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