Code Question: Can I use an <img> tag to send cookies across domains?

Look at this situation:

www.websitea.com displays an img tag with a src attribute of www.websiteb.com/image.aspx?id=5 and style="display:none"
www.websiteb.com returns an clear image, in addition to a cookie with a name of referrer and value of 5 (created server-side from validated querystring.)

Would the cookie be created on domain www.websitea.com or www.websiteb.com?

Currently I'm sure a series of redirects with querystrings and to achieve cross-domain cookies, but I came up with this image idea a little ago. I guess I could also use an iframe.

Thanks!

From stackoverflow

The cookie would be created for websiteb.com.
The cookie is created from the request to websiteb.com so yea... the cookie goes to websiteb scope
Check out: cross-domain-user-tracking

Someone mentions using a 1x1 image for tracking across domains.

Shawn Simon : i marked this the answer because it eventually solved my problem with ie6

Ok looks good. Tested in all browsers. Added a P3P tag for IE6, not sure if it was necessary though.

<%@ Page Language="VB" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<script runat="server">
    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs)
        Response.AddHeader("P3P", "CP=""CAO PSA OUR""")
        Dim passedlocalizeID As String = Request.QueryString("id")
        Dim localizeID As Integer
        If passedlocalizeID IsNot Nothing AndAlso Int32.TryParse(passedlocalizeID, localizeID) Then
            Dim localizer As New Localizer
            localizer.LocalizeTo(localizeID)
        End If
    End Sub
</script>

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title>Redirecting . . .</title>
    <meta http-equiv="refresh" content="0;URL=/" />
</head>
<body>
    <form id="form1" runat="server">
    <div>
    </div>
    </form>
</body>
</html>

You're on the right track. As others have mentioned, the cookie would be created for websiteb.com.

To overcome issues with IE you'll probably need to ad a Compact Privacy policy.

Start here: http://msdn.microsoft.com/en-us/library/ms537342.aspx and Google for the rest.

Code Question

Monday, March 7, 2011

Can I use an <img> tag to send cookies across domains?

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