调用 Web API 的桌面应用:使用设备代码流获取令牌
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:
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)。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:
- 要请求其访问令牌的
scopes
。 - 接收
DeviceCodeResult
的回调。
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://video2.skills-academy.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。