If you’re ever stuck wondering why Live HTTP Headers and Firebug are telling you your “Cookie:” request headers don’t match the “Set-Cookie:” response headers you’ve just been sent, here’s a couple of points and gotchas worth remembering:
- A cookie can only be overwritten (or deleted) by a subsequent cookie exactly matching the name, path and domain of the original cookie. Even though a cookie with domain “.example.org” set by www.example.org is perfectly valid, it will not overwrite a previous cookie of the same name which was set against “www.example.org”. Instead, both cookies will be stored, and on subsequent requests only one will be sent.
- If multiple cookies of the same name match a given request URI, one is chosen by the browser.
The more specific the path, the higher the precedence. However precedence based on other attributes, including the domain, is unspecified, and may vary between browsers. This means that if you have set cookies of the same name against “.example.org” and “www.example.org”, you can’t be sure which one will be sent back. - The HTTP state object is called a cookie
for no compelling reason
according to the preliminary specification from Netscape.
September 26th, 2007 at 6:48 am
Also, Cookies are good with milk. Oh wait, wrong cookie.
September 27th, 2007 at 10:09 pm
And they are good with a nice cup of tea.
September 29th, 2007 at 7:43 pm
I’ve heard they make excellent coasters.
December 15th, 2007 at 7:44 pm
The current standard for cookies is RFC 2965, and 2109 is obsolete. In the current standard, multiple cookies with the same name and different path/domain components are allowed, and they are sent by the browser in order from most-specific to least-specific. The current versions of both Firefox and IE behave according to the new standard.