利用DelegatingHandler实现Web Api 的Api key校验

客户端在请求Web Api时可以有以下两种方式提供API key

client.BaseAddress = new Uri(url);
client.DefaultRequestHeaders.Accept.Clear();
client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
client.DefaultRequestHeaders.Add("X-ApiKey","00000");

编写ApiKeyHandler

public class ApiKeyHandler : DelegatingHandler
{
public string Key { get; set; }

public ApiKeyHandler(string key,HttpConfiguration httpConfiguration)
{
this.Key = key;
InnerHandler = new HttpControllerDispatcher(httpConfiguration);
}

protected override Task<HttpResponseMessage> SendAsync(
HttpRequestMessage request, CancellationToken cancellationToken)
{
if (!ValidateKey(request))
{
var response = new HttpResponseMessage(HttpStatusCode.Forbidden);
var tsc = new TaskCompletionSource<HttpResponseMessage>();
tsc.SetResult(response);
return tsc.Task;
}
return base.SendAsync(request, cancellationToken);
}

private bool ValidateKey(HttpRequestMessage message)
{
IEnumerable<string> apiKeyHeaderValues = null;

if (message.Headers.TryGetValues("X-ApiKey", out apiKeyHeaderValues))
{
var apiKeyHeaderValue = apiKeyHeaderValues.First();
return (apiKeyHeaderValue == this.Key)
// ... your authentication logic here ...
/*
var username = (apiKeyHeaderValue == "00000" ? "Maarten" : "OtherUser");

var usernameClaim = new Claim(ClaimTypes.Name, username);
var identity = new ClaimsIdentity(new[] { usernameClaim }, "ApiKey");
var principal = new ClaimsPrincipal(identity);

Thread.CurrentPrincipal = principal;
*/
}

/*
var query = message.RequestUri.ParseQueryString();
string key = query["key"];
return (key == this.Key);
*/
}

配置到特定的路由上去

config.Routes.MapHttpRoute(
name: "DefaultApi",
routeTemplate: "api/{controller}/{id}",
defaults: new { id = RouteParameter.Optional },
constraints: null,
handler: new ApiKeyHandler("12345", GlobalConfiguration.Configuration)

);