Happy New Year to you all.
Before Christmas I released version 0.6.3 of Modify Headers. This version adds support for the Firefox 3 beta 2. For current users this will automatically update, otherwise, please download from Mozilla Addons.
Update: XHTML Mobile Profile 0.5.2 has been updated to support Firefox 3 beta 2.
First reading about the “Modify Headers” extension I thought: That’s what I ‘m looking for.
But after installing the extension, it revealed to modify outging (request-) headers only. No possibility to modify or remove server-sided response headers. Yes, I should have read your extension-description more carefully, you mentioned it.
Ok, you may ask, why should I want to filter response headers? Answer: There are several reasons why you may want to filter server headers. One of them is to force caching in firefox.
Many servers send anti-cache headers, preventing firefox to cache documents and/or pictures, so there will always be a (full) reload when pushing the back button. That’s really annoying. Anti-cache headers may be AGE, CACHE-CONTROL, EXPIRES, ETAG, PRAGMA, VARY and even more headers.
I really would appreciate adding that feature.
Hi NettiCat. I had always thought that response headers are immutable, but I had a look at the documentation and it looks possible. I’ve added an enhancement request here: https://www.mozdev.org/bugs/show_bug.cgi?id=18455
Feel free to add yourself as a CC on this.
I have a lot of other features to add first, but I’ll add this to the roadmap for version 0.8 or 0.9.
Thank you! (for adding my request to the road map)
P.S.
ACString getResponseHeader(in ACString header);
void setResponseHeader(in ACString header, in ACString value, in boolean merge);
http://developer.mozilla.org/en/docs/nsIHttpChannel
This may not be of interest for bloggers, but as all postings will be reviewed I’ll post it anyway
I made a small extension (BetterCache). It is a working demo concerning modification of response headers. You may use it in your own project:
function RespHeaderObserver()
{
this.register();
}
RespHeaderObserver.prototype = {
observe: function(subject, topic, data) {
if (topic == “http-on-examine-response”) {
var headers = new Array();
headers[0] = “Age”;
headers[1] = “Cache-Control”;
headers[2] = “Date”;
headers[3] = “ETag”;
headers[4] = “Expires”;
headers[5] = “Last-Modified”;
headers[6] = “Pragma”;
headers[7] = “Vary”;
//headers[8] = “Set-Cookie”; //not anti-cache, but a better testpattern
var httpChannel = subject.QueryInterface(Components.interfaces.nsIHttpChannel);
//need to test every (above defined) header for existance. If not existant, getResponseHeader will throw an exception.
for(i = 0; i < headers.length; i++){
var headerval = “”;
var replacement = “”;
try{
headerval = httpChannel.getResponseHeader (headers[i]);
if(i == 6)//special case Pragma
replacement = headerval.replace(/no\-cache/g, “”);
httpChannel.setResponseHeader(headers[i], replacement, false);
//alert(headers[i]+’='+headerval);
}catch(e){}//NS_ERROR_(header_)NOT_AVAILABLE
}
headers = null;
return;
}
},
register: function() {
var observerService = Components.classes["@mozilla.org/observer-service;1"].getService(Components.interfaces.nsIObserverService);
observerService.addObserver(this, “http-on-examine-response”, false);
},
unregister: function() {
var observerService = Components.classes["@mozilla.org/observer-service;1"].getService(Components.interfaces.nsIObserverService);
try{
observerService.removeObserver(this, “http-on-examine-response”);
}catch(e){}
}
}
//observer needs to be registered only once, so better use a XPT file
window.addEventListener(“load”, function(evnt) { observer = new RespHeaderObserver(); }, true);
window.addEventListener(“unload”, function(evnt) { observer.unregister(); }, true);
Hi,
I found your extension today and think it’s really great. It would be perfect for me when I could specify which headers are sent to which url (with regex).
Example:
x-test0 = 0000 @ http://a-z\./]*
x-test = 1234 @ https://localhost/*
x-test2 = 5678 @ http://www\.mozilla\.org/*
and so on… Just an idea
Hi Crono, A feature similar to this is already on the roadmap.
Hi Gareth,
very nice – thanks for the info
bye
I think the best reason to be able to modify server side headers is… freedom.
Congratulations for this awesome extension!, but I also miss the modify response headers feature. Another usage could be to filter the location header for testing purposes, the developers would appreciate it very much.
Best regards.
MazarD