Using Fiddler: Inject cookie into all subsequent requests from initial request

Question

I have a batch of requests in Fiddler, the first is a login request and returns a valid cookie. The rest need to use this cookie, I know I can break and edit headers but is it possible to automatically script this behaviour? I'm pretty new to Fiddler but it looks powerful so I'm hoping this is possible, anyone know how or where to start?

Answer 1

To manually add a header, use the Filters tab and use the Request Headers section.

To automatically add a header, click Rules > Customize Rules. Scroll to OnBeforeResponse and write code that stores the target cookie in a global variable declared just inside the Handlers function, eg

static var m_MyCookie: String;

Then, inside the OnBeforeRequest function, use that variable, eg

if (!String.IsNullOrEmpty(m_MyCookie)) oSession.oRequest["Cookie"] = (m_MyCookie + ";" + oSession.oRequest["Cookie"] )

If you're only trying to add this header to specific requests, use, for instance, the oSession.uriContains function to determine whether the target URL is one that you want to have the cookie.