[翻译]创建ASP.NET WebApi RESTful 服务（8）

2022-10-13 11:28:07

本章讨论创建安全的WebApi服务，到目前为止，我们实现的API都是基于未加密的HTTP协议，大家都知道在Web中传递身份信息必须通过HTTPS，接下来我们来实现这一过程。

使用HTTPS

其实可以通过IIS配置，将整个WebApi的访问都配置为Https，但实际上，如果希望只是对部分方法进行认证，那就必须通过认证身份信息进行处理。

下面介绍通过Filter来实现这一过程，如果身份认证不通过，就返回一条信息，提示访问者通过https进行访问。

   1:  public class ForceHttpsAttribute : AuthorizationFilterAttribute

   2:      {

   3:          public override void OnAuthorization(System.Web.Http.Controllers.HttpActionContext actionContext)

   4:          {

   5:              var request = actionContext.Request;

6:

   7:              if (request.RequestUri.Scheme != Uri.UriSchemeHttps)

   8:              {

   9:                  var html = "<p>Https is required</p>";

10:

  11:                  if (request.Method.Method == "GET")

  12:                  {

  13:                      actionContext.Response = request.CreateResponse(HttpStatusCode.Found);

  14:                      actionContext.Response.Content = new StringContent(html, Encoding.UTF8, "text/html");

15:

  16:                      UriBuilder httpsNewUri = new UriBuilder(request.RequestUri);

  17:                      httpsNewUri.Scheme = Uri.UriSchemeHttps;

  18:                      httpsNewUri.Port = 443;

19:

  20:                      actionContext.Response.Headers.Location = httpsNewUri.Uri;

  21:                  }

  22:                  else

  23:                  {

  24:                      actionContext.Response = request.CreateResponse(HttpStatusCode.NotFound);

  25:                      actionContext.Response.Content = new StringContent(html, Encoding.UTF8, "text/html");

  26:                  }

27:

  28:              }

  29:          }

  30:      }

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通过actionContext参数获取Request和Response对象，对URI进行检查，如果不是以HTTPS开头，就返回443代码。

使用的方法有两种，一种是在WebAPIConfig中注册为全局的Attribute。

   1:    public static void Register(HttpConfiguration config)

   2:      {

   3:          config.Filters.Add(new ForceHttpsAttribute());

   4:      }

另一种是对制定的类或者方法进行拦截。

   1:  //Enforce HTTPS on the entire controller

   2:      [Learning.Web.Filters.ForceHttps()]

   3:      public class CoursesController : BaseApiController

   4:      {

   5:          //Enforce HTTPS on POST method only

   6:          [Learning.Web.Filters.ForceHttps()]

   7:          public HttpResponseMessage Post([FromBody] CourseModel courseModel)

   8:          {

9:

  10:          }

  11:      }

通过Basic Authentication进行认证

当前所有的API都是Public的，网络上的任意用户都可以请求资源。实际的项目中肯定要对访问者进行必要的限制。

假设对于客户端的请求“http://{your_port}/api/students/{userName}”，当有正确的身份信息时，我们返回username为 “TaiseerJoudeh”的信息，否则，返回错误；
如果请求是POST类型，如“http://{your_port}/api/courses/2/students/{userName}”，那么修改者也必须通过身份认证才可以进行修改。

什么是Basic Authentication

Basic Authentication提供了一种在Http Request被处理之前先行进行身份认证的模式，它在防止Dos等方面具有重要作用。Basic Authentication要求在请求时必须在Http Header提供基于Base64编码的用户名和密码信息。这种认证一般应该通过HTTPS来实现。

   1:   public class LearningAuthorizeAttribute : AuthorizationFilterAttribute

   2:      {

3:

   4:          [Inject]

   5:          public LearningRepository TheRepository { get; set; }

6:

   7:          public override void OnAuthorization(System.Web.Http.Controllers.HttpActionContext actionContext)

   8:          {

   9:              //Case that user is authenticated using forms authentication

  10:              //so no need to check header for basic authentication.

  11:              if (Thread.CurrentPrincipal.Identity.IsAuthenticated)

  12:              {

  13:                  return;

  14:              }

15:

  16:              var authHeader = actionContext.Request.Headers.Authorization;

17:

  18:              if (authHeader != null)

  19:              {

  20:                  if (authHeader.Scheme.Equals("basic", StringComparison.OrdinalIgnoreCase) &&

  21:                  !String.IsNullOrWhiteSpace(authHeader.Parameter))

  22:                  {

  23:                      var credArray = GetCredentials(authHeader);

  24:                      var userName = credArray[0];

  25:                      var password = credArray[1];

26:

  27:                      if (IsResourceOwner(userName, actionContext))

  28:                      {

  29:                          //You can use Websecurity or asp.net memebrship provider to login, for

  30:                          //for he sake of keeping example simple, we used out own login functionality

  31:                          if (TheRepository.LoginStudent(userName, password))

  32:                          {

  33:                              var currentPrincipal = new GenericPrincipal(new GenericIdentity(userName), null);

  34:                              Thread.CurrentPrincipal = currentPrincipal;

  35:                              return;

  36:                          }

  37:                      }

  38:                  }

  39:              }

40:

  41:              HandleUnauthorizedRequest(actionContext);

  42:          }

43:

  44:          private string[] GetCredentials(System.Net.Http.Headers.AuthenticationHeaderValue authHeader)

  45:          {

46:

  47:              //Base 64 encoded string

  48:              var rawCred = authHeader.Parameter;

  49:              var encoding = Encoding.GetEncoding("iso-8859-1");

  50:              var cred = encoding.GetString(Convert.FromBase64String(rawCred));

51:

  52:              var credArray = cred.Split(':');

53:

  54:              return credArray;

  55:          }

56:

  57:          private bool IsResourceOwner(string userName, System.Web.Http.Controllers.HttpActionContext actionContext)

  58:          {

  59:              var routeData = actionContext.Request.GetRouteData();

  60:              var resourceUserName = routeData.Values["userName"] as string;

61:

  62:              if (resourceUserName == userName)

  63:              {

  64:                  return true;

  65:              }

  66:              return false;

  67:          }

68:

  69:          private void HandleUnauthorizedRequest(System.Web.Http.Controllers.HttpActionContext actionContext)

  70:          {

  71:              actionContext.Response = actionContext.Request.CreateResponse(HttpStatusCode.Unauthorized);

72:

  73:              actionContext.Response.Headers.Add("WWW-Authenticate",

  74:              "Basic Scheme='eLearning' location='http://localhost:8323/account/login'");

75:

  76:          }

  77:      }

上述代码实现了以下逻辑：

从Request Header中获取认证信息；
确认Header的Schema被设置为basic，并包含了正确的Base64编码字符串；
将字符串转换为“username:password”格式，获取各自内容；
验证身份信息，确定是否具有相应权限；
如果Credentials验证无误，设置当前线程的Identity信息，以便子请求能够重用；
如果验证有无，则返回401错误。

现在可以对指定的方法进行标记。

   1:      public class StudentsController : BaseApiController

   2:      {

   3:          [LearningAuthorizeAttribute]

   4:          public HttpResponseMessage Get(string userName)

   5:          {

6:

   7:          }

   8:      }

9:

  10:      public class EnrollmentsController : BaseApiController

  11:      {

  12:          [LearningAuthorizeAttribute]

  13:          public HttpResponseMessage Post(int courseId, [FromUri]string userName, [FromBody]Enrollment enrollment)

  14:          {

15:

  16:          }

  17:      }

现在分别用FireFox和Fiddler进行测试。假设路径如下：http://localhost:{your_port}/api/students/TaiseerJoudeh。

FireFox：返回401，因为没有身份信息，一个弹出框会弹出，要求输入用户名和密码。输入正确的用户名和密码，就可以看到返回的json信息。而接下来的子请求，则无需再进行认证；
Fiddler：需要先拼接一个Base64加密“username:password”字符串，可以通过这里实现。注意：这不能算是加密，真正的加密必须通过HTTPS实现。当用户名密码正确时，会返回200和正确的json信息。

来源：http://bitoftech.net/2013/12/03/enforce-https-asp-net-web-api-basic-authentication/

码农公寓

使用HTTPS

通过Basic Authentication进行认证

什么是Basic Authentication

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