[筆記][WebAPI][MessageHandler]在MessageHandler中讀取(get)寫入(set) Cookie
緣起：
小喵想研究 WebAPI 中，怎麼樣去處理CSRF的防護，在ASP.NET WebForm中，會自動產生「確認碼」放在HiddenFileld，並且每次接受Request的時候會自動檢查。那麼在WebAPI中，應該用什麼樣的方式來處理呢?小喵想到，或許可以用 MessageHandler 搭配 Cookie來處理。這一篇就來記錄怎麼在 Message Handler 中，存取Cookie
MessageHandler檔案
首先，先新增 MessageHandler 檔案。在 Models 中，新增一個類別，內容如下：
Imports System.Net.Http
Imports System.Net.Http.Headers
Public Class TestMessageHandler
Inherits DelegatingHandler
Protected Overrides Async Function SendAsync(request As HttpRequestMessage, cancellationToken As Threading.CancellationToken) As Threading.Tasks.Task(Of HttpResponseMessage)
'處理Request
Dim TestID As String = getCookie(request, "TestID")
'透過非同步方式運作，這裡來承接回傳時的response內容
Dim response = Await MyBase.SendAsync(request, cancellationToken)
TestID = Format(Now, "yyyyMMddHHmmss") & Guid.NewGuid().ToString.ToUpper
Dim tCookie As New CookieHeaderValue("TestID", TestID)
tCookie.Expires = DateAdd(DateInterval.Minute, 20, Now)
tCookie.Domain = request.RequestUri.Host
tCookie.Path = "/"
Dim Cookies As IEnumerable(Of CookieHeaderValue) = New CookieHeaderValue() {New CookieHeaderValue("TestID", TestID)}
response.Headers.AddCookies(Cookies)
'把response繼續往前傳
Return response
End Function
''' <summary>
''' 取得Cookie
''' </summary>
''' <param name="request">Request</param>
''' <param name="CookieName">Cookie的名字</param>
''' <returns></returns>
Public Function getCookie(ByVal request As HttpRequestMessage, ByVal CookieName As String) As String
Dim Rc As String = ""
Dim cookie As CookieHeaderValue = request.Headers.GetCookies(CookieName).FirstOrDefault()
If cookie IsNot Nothing Then
Rc = cookie(CookieName).Value
End If
Return Rc
End Function
End Class
Global.asax 註冊 MessageHandler
接著，把剛剛的 MessageHandler 註冊到 Global.asax中
Imports System.Web.Http
Imports System.Web.Optimization
Public Class WebApiApplication
Inherits System.Web.HttpApplication
''' <summary>
''' 掛載Message Handler
''' </summary>
''' <param name="config"></param>
''' <remarks></remarks>
Shared Sub Configure(config As HttpConfiguration)
'這裡可以設定要掛載多組Message Handler
config.MessageHandlers.Add(New TestMessageHandler())
End Sub
Protected Sub Application_Start()
'在Application_Start事件，呼叫寫的Sub掛上
Configure(GlobalConfiguration.Configuration)
AreaRegistration.RegisterAllAreas()
GlobalConfiguration.Configure(AddressOf WebApiConfig.Register)
FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters)
RouteConfig.RegisterRoutes(RouteTable.Routes)
BundleConfig.RegisterBundles(BundleTable.Bundles)
End Sub
End Class
參考資料
Example: Set and Retrieve Cookies in a Message Handler
以下是簽名：
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