如何从 azure OAuth 2.0 令牌 (v2) 端点获取/生成访问令牌？

Question

我想从给定的 URL 获取访问令牌：

https://login.microsoftonline.com/{AzureTenantId}/oauth2/v2.0/token

我正在传递以下参数，如 Microsoft 文档中所述： client_id, scope, client_secret, grant_type。

当我点击此 URL 时，我收到“400 Bad Request”响应。

当我从 Postman 尝试同样的操作时，它成功并为我提供了一个访问令牌：

但不是来自我的代码：

public async Task<string> GetAuthorizationToken(string clientId, string ServicePrincipalPassword, string AzureTenantId) {
            var result = "";
            var requestURL = "https://login.microsoftonline.com/{AzureTenantId}/oauth2/v2.0/token";
            var _httpClient = new HttpClient();

            var model = new {
                client_id = clientId,
                scope = "{clentID}/.default",
                client_secret = ServicePrincipalPassword,
                grant_type = "client_credentials"
            };

            HttpContent httpContent = new StringContent(JsonConvert.SerializeObject(model), System.Text.Encoding.UTF8, "application/x-www-form-urlencoded");

            var httpRequestMessage = new HttpRequestMessage(HttpMethod.Post, new Uri(requestURL)) {
                Content = httpContent
            };

            using (var response = await _httpClient.SendAsync(httpRequestMessage)) {
                if (response.IsSuccessStatusCode) {
                    var responseStream = await response.Content.ReadAsStringAsync();
                    return result;
                } else {
                    return result;
                }
            }

Answer 1

您的http请求格式不正确，请尝试：

var _httpClient = new HttpClient();

var content = new FormUrlEncodedContent(new Dictionary<string, string> {
              { "client_id", "ClientID" },
              { "client_secret", "YourSecret" },
              { "grant_type", "client_credentials" },
              { "scope", "https://graph.microsoft.com/.default" },
            });

var httpRequestMessage = new HttpRequestMessage(HttpMethod.Post, new Uri(requestURL))
{
    Content = content
};

using (var response = await _httpClient.SendAsync(httpRequestMessage))
{
    if (response.IsSuccessStatusCode)
    {
        var responseStream = await response.Content.ReadAsStringAsync();
        return result;
    }
    else
    {
        return result;
    }
}

Answer 2

正如Nan Yu 的答案的补充，您可能需要考虑使用库来实现此目的，而不是尝试自己实现。

例如，使用适用于 .NET 的 Microsoft 身份验证库 (MSAL)，您将获得如下访问令牌：

// Setup MSAL
var client = ConfidentialClientApplicationBuilder
    .Create("{client-id}")
    .WithAuthority("https://login.microsoftonline.com/{tenant-id}/v2.0")
    .WithClientSecret(/* retrieve from secure storage, do *NOT* put the secret in your code! */)
    .Build();

// Retrieve an access token
var scopes = new string[] { "https://graph.microsoft.com/.default" };
var authResult = await clientApplication.AcquireTokenForClient(scopes).ExecuteAsync();

// The access token is in $authResult.AccessToken

一个重要的优点是，您无需担心跟踪令牌有效性即可知道何时需要获取新令牌。如果您需要获取新的令牌，您只需AcquireTokenForClient再次调用，它就会为您确定是否需要获取新的令牌，或者您是否可以使用已经缓存的令牌。