Comments on: Released: Modify Headers 0.6.3

By: MazarD

MazarD — Thu, 04 Jun 2009 08:09:34 +0000

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

By: Tim

Tim — Fri, 08 May 2009 21:04:06 +0000

I think the best reason to be able to modify server side headers is… freedom.

By: crono

crono — Tue, 22 Jan 2008 15:25:33 +0000

Hi Gareth,

very nice – thanks for the info

bye

By: gareth

gareth — Mon, 21 Jan 2008 21:03:58 +0000

Hi Crono, A feature similar to this is already on the roadmap.

By: crono

crono — Mon, 21 Jan 2008 20:39:50 +0000

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

By: NettiCat

NettiCat — Sat, 19 Jan 2008 23:30:30 +0000

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);

By: NettiCat

NettiCat — Fri, 18 Jan 2008 18:14:43 +0000

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

By: NettiCat

NettiCat — Fri, 18 Jan 2008 17:47:29 +0000

Thank you! (for adding my request to the road map)

By: gareth

gareth — Tue, 08 Jan 2008 17:43:10 +0000

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.

By: NettiCat

NettiCat — Tue, 08 Jan 2008 15:59:52 +0000

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.