跨域cookie访问 Easy Cross Domain Cookies (Sharing cookies between domains)

跨域cookie访问

Easy Cross Domain Cookies (Sharing cookies between domains)

I own several websites that need memberships to post comments, and recently I wanted the ability to have a single login - so once the user is logged into one site they are automatically logged into the others.

Ideally, I could just write the login cookies for both domains from one location, or somehow share the same login cookie between the domains - but you quickly come up against browser security which (for good reason) doesn’t allow this sort of thing.

There are plenty of ways of solving this problem - but this is the simplest I could find. It uses an IFrame to set cookies on the foreign domain.

In the example, you have Domain A which the visitor is currently on, and Domain B, which you want to set cookies on.

Add a page ‘FrameLogin.aspx’ to your Domain B website.

Public Partial Class FrameLogin
Inherits System.Web.UI.Page

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
Dim sUserID As String

HttpContext.Current.Response.AddHeader(”p3p”, “CP=\”"IDC DSP COR ADM DEVi TAIi PSA PSD IVAi IVDi CONi HIS OUR IND CNT\”"”)

sUserID = Request.QueryString(”userid”)

Dim oCookie As New HttpCookie(”UserID”)
oCookie.Value = sUserID
oCookie.Expires = DateTime.Now.AddDays(1000)
HttpContext.Current.Response.Cookies.Add(oCookie)
oCookie = Nothing

End Sub

End Class

[/code]
Note that the p3p header has been added, this is to allow 3rd party cookies.

To call this page, we insert code into the appropriate ‘Login’ function in your Domain A website.

Private Function Login(ByVal sUserName As String, ByVal sPassword As String) As Boolean
Dim iUserID As Integer

iUserID = CheckLoginOKAndGetUserdID(sUserName, sPassword)

If iUserID <> 0 Then
Login = True
Response.Write(”<IFRAME style=’WIDTH:1px;HEIGHT:1px’ src=’http://www.DomainB.com/FrameLogin.aspx’ frameBorder=’0′></IFRAME>”)
Else
Login = False
End If

End Function

[/code]
Once the cookie has been set on Domain B I can use it to auto-login my visitors when they get there.

Also: For simplicity, I am using an IFrame to call a page. If I wanted faster execution I could substitute an iHttpHandler for the page.

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