I am trying to accomplish some specific test requirement.
One of the requirement now is to redirect some nonexistent url to specific ip, which is what the dns is doing. I think firefox is using internal dns cache. But I cannot find a proper service that I can use to change such kind of dns cache. On the other hand, i have no idea if firefox support some kind of service to customize the dns process, I mean give a customized result instead of really getting from DNS Server.
As I need to start many firefox process to do the work concurrently, so I cannot do this simply by changing the system hosts file, cause it will affect other process.
Any idea?
No, modifying DNS responses isn't possible in Firefox, the DNS service merely allows triggering a DNS request. What you could do is recognizing NS_ERROR_UNKNOWN_HOST response and somehow redirecting it to your server. While recognizing isn't particularly hard, redirecting is complicated. You could add a progress listener and check whether a request finished in onStateChange method (if (aFlag & STATE_STOP)). The parameter aStatus gives you the status of the request, you would be looking for status Components.results.NS_ERROR_UNKNOWN_HOST. And for top-level requests (aFlag & STATE_WINDOW) you could change window location to make a request to a different server instead. For other requests - don't know how one would "redirect" there.