通过

调用 Web API 的桌面应用：使用设备代码流获取令牌

  • 项目

如果你正在编写一个不包含 Web 控件的命令行工具，并且无法或者不想要使用前面所述的流，请使用设备代码流。

设备代码流

使用 Microsoft Entra ID 进行的交互式身份验证需要 Web 浏览器。 有关详细信息，请参阅 Web 浏览器的用法。 为了对不提供 Web 浏览器的设备或操作系统上的用户进行身份验证，设备代码流可让用户使用另一台设备（例如某台计算机或手机）以交互方式登录。 通过使用设备代码流，应用程序将通过专为这些设备或操作系统设计的两步过程获取令牌。 此类应用程序的例子包括 iOT 上运行的应用程序或命令行工具 (CLI)。 其思路是：

  1. 每当需要用户身份验证时，应用就会为用户提供一个代码。 系统要求用户使用另一台设备（例如，已连接到 Internet 的智能手机）转到某个 URL（例如 https://microsoft.com/devicelogin）。 然后系统会提示用户输入代码。 完成此操作后，网页将引导用户进行常规的身份验证操作，其中包括同意提示和多重身份验证（如有必要）。

  2. 身份验证成功后，命令行应用通过后端通道接收所需的令牌，并使用它们来执行所需的 Web API 调用。

用法

IPublicClientApplication 包含名为 AcquireTokenWithDeviceCode 的方法。

 AcquireTokenWithDeviceCode(IEnumerable<string> scopes,
                            Func<DeviceCodeResult, Task> deviceCodeResultCallback)

该方法用作参数：

以下示例代码显示了最新事例的概要，并解释了可能出现的各种异常及其缓解措施。 有关完整的功能代码示例，请参阅 GitHub 上的 active-directory-dotnetcore-devicecodeflow-v2。

private const string ClientId = "<client_guid>";
private const string Authority = "https://login.microsoftonline.com/contoso.com";
private readonly string[] scopes = new string[] { "user.read" };

static async Task<AuthenticationResult> GetATokenForGraph()
{
    IPublicClientApplication pca = PublicClientApplicationBuilder
            .Create(ClientId)
            .WithAuthority(Authority)
            .WithDefaultRedirectUri()
            .Build();

    var accounts = await pca.GetAccountsAsync();

    // All AcquireToken* methods store the tokens in the cache, so check the cache first
    try
    {
        return await pca.AcquireTokenSilent(scopes, accounts.FirstOrDefault())
            .ExecuteAsync();
    }
    catch (MsalUiRequiredException ex)
    {
        // No token found in the cache or Azure AD insists that a form interactive auth is required (e.g. the tenant admin turned on MFA)
        // If you want to provide a more complex user experience, check out ex.Classification

        return await AcquireByDeviceCodeAsync(pca);
    }
}

private static async Task<AuthenticationResult> AcquireByDeviceCodeAsync(IPublicClientApplication pca)
{
    try
    {
        var result = await pca.AcquireTokenWithDeviceCode(scopes,
            deviceCodeResult =>
            {
                    // This will print the message on the console which tells the user where to go sign-in using
                    // a separate browser and the code to enter once they sign in.
                    // The AcquireTokenWithDeviceCode() method will poll the server after firing this
                    // device code callback to look for the successful login of the user via that browser.
                    // This background polling (whose interval and timeout data is also provided as fields in the
                    // deviceCodeCallback class) will occur until:
                    // * The user has successfully logged in via browser and entered the proper code
                    // * The timeout specified by the server for the lifetime of this code (typically ~15 minutes) has been reached
                    // * The developing application calls the Cancel() method on a CancellationToken sent into the method.
                    //   If this occurs, an OperationCanceledException will be thrown (see catch below for more details).
                    Console.WriteLine(deviceCodeResult.Message);
                return Task.FromResult(0);
            }).ExecuteAsync();

        Console.WriteLine(result.Account.Username);
        return result;
    }

    // TODO: handle or throw all these exceptions depending on your app
    catch (MsalServiceException ex)
    {
        // Kind of errors you could have (in ex.Message)

        // AADSTS50059: No tenant-identifying information found in either the request or implied by any provided credentials.
        // Mitigation: as explained in the message from Azure AD, the authoriy needs to be tenanted. you have probably created
        // your public client application with the following authorities:
        // https://login.microsoftonline.com/common or https://login.microsoftonline.com/organizations

        // AADSTS90133: Device Code flow is not supported under /common or /consumers endpoint.
        // Mitigation: as explained in the message from Azure AD, the authority needs to be tenanted

        // AADSTS90002: Tenant <tenantId or domain you used in the authority> not found. This may happen if there are
        // no active subscriptions for the tenant. Check with your subscription administrator.
        // Mitigation: if you have an active subscription for the tenant this might be that you have a typo in the
        // tenantId (GUID) or tenant domain name.
    }
    catch (OperationCanceledException ex)
    {
        // If you use a CancellationToken, and call the Cancel() method on it, then this *may* be triggered
        // to indicate that the operation was cancelled.
        // See https://learn.microsoft.com/dotnet/standard/threading/cancellation-in-managed-threads
        // for more detailed information on how C# supports cancellation in managed threads.
    }
    catch (MsalClientException ex)
    {
        // Possible cause - verification code expired before contacting the server
        // This exception will occur if the user does not manage to sign-in before a time out (15 mins) and the
        // call to `AcquireTokenWithDeviceCode` is not cancelled in between
    }
}

后续步骤

转到此方案中的下一篇文章：从桌面应用调用 Web API。