Firefox Addon observer http-on-modify-request not working properly

Question

I have a weird bug in my addon, the addon itself needs to add a request header parameters for a specific domain, it's all working, but the bug is, that the observer http-on-modify-request is not called at start, only if I reload the page, then it's working.

I mean:

1. I go to mysite.com/ - no header modified,
2. I reload page - header modefied
3. reload again - header modefied
4. new tab at mysite.com/ - no header modified
5. reload tab - header modefied

My code, I'm using the addon sdk:

exports.main = function(options,callbacks) {

// Create observer 
httpRequestObserver =  
{  
  observe: function(subject, topic, data)  
  {  

    if (topic == "http-on-modify-request") {


    //only identify to specific preference domain
    var windowsService = Cc['@mozilla.org/appshell/window-mediator;1'].getService(Ci.nsIWindowMediator);
    var uri = windowsService.getMostRecentWindow('navigator:browser').getBrowser().currentURI;
    var domainloc = uri.host;

        if (domainloc=="mysite.com"){
            var httpChannel = subject.QueryInterface(Ci.nsIHttpChannel);  
            httpChannel.setRequestHeader("x-test", "test", false);  
        }
    }  


  }, 

  register: function()  
  { 
    var observerService = Cc["@mozilla.org/observer-service;1"]  
            .getService(Ci.nsIObserverService);  
    observerService.addObserver(this, "http-on-modify-request", false);         
  },  

  unregister: function()  
  {
    var observerService = Cc["@mozilla.org/observer-service;1"]  
            .getService(Ci.nsIObserverService);  
    observerService.removeObserver(this, "http-on-modify-request"); 


  }  
};


//register observer
httpRequestObserver.register();

};

exports.onUnload = function(reason) {

httpRequestObserver.unregister();
};

Please help me, I searched for hours with no results. The code is working, but not at first time of page loading, only if I reload.

The goal is that only on mysite.com, there will be a x-text=test header request, all the time, but only on mysite.com.

Answer 1

currentUri on browser is the Uri that is currently loaded in the tab. At "http-on-modify-request" notification time, the request is not sent to the server yet, so if it's a new tab, the browser doesn't have any currentUri. When you refresh the tab in place, it uses the uri of the current page, and it seemingly works.

Try this instead:

if (topic == "http-on-modify-request") {
    var httpChannel = subject.QueryInterface(Ci.nsIHttpChannel);  
    var uri = httpChannel.URI;
    var domainloc = uri.host;

    //only identify to specific preference domain
    if (domainloc == "mysite.com") {
        httpChannel.setRequestHeader("x-test", "test", false);
    }
}