Due to weird domain/subdomain cookie issues that I'm getting, I'd like to know how browsers handle cookies. If they do it in different ways, it would also be nice to know the differences.
In other words - when a browser receives a cookie, that cookie MAY have a domain and a path attached to it. Or not, in which case the browser probably substitutes some defaults for them. Question 1: what are they?
Later, when the browser is about to make a request, it checks its cookies and filters out the ones it should send for that request. It does so by matching them against the requests path and domain. Question 2: what are the matching rules?
The reason I'm asking this is because I'm interested in some edge cases. Like:
.example.com be available for www.example.com?.example.com be available for example.com?example.com be available for www.example.com?example.com be available for anotherexample.com?www.example.com be able to set cookie for example.com?www.example.com be able to set cookie for www2.example.com?www.example.com be able to set cookie for .com?Added 2:
Also, could someone suggest how I should set a cookie so that:
www.example.com or example.com;www.example.com and example.com.Although there is the RFC 2965 (Set-Cookie2, had already obsoleted RFC 2109) that should define the cookie nowadays, most browsers don’t fully support that but just comply to the original specification by Netscape.
There is a distinction between the Domain attribute value and the effective domain: the former is taken from the Set-Cookie header field and the latter is the interpretation of that attribute value. According to the RFC 2965, the following should apply:
. it will be added by the client).Having the effective domain it must also domain-match the current requested domain for being set; otherwise the cookie will be revised. The same rule applies for choosing the cookies to be sent in a request.
Mapping this knowledge onto your questions, the following should apply:
Domain=.example.com will be available for www.example.comDomain=.example.com will be available for example.comDomain=example.com will be converted to .example.com and thus will also be available for www.example.comDomain=example.com will not be available for anotherexample.comAnd to set and read a cookie for/by www.example.com and example.com, set it for .www.example.com and .example.com respectively. But the first (.www.example.com) will only be accessible for other domains below that domain (e.g. foo.www.example.com or bar.www.example.com) where .example.com can also be accessed by any other domain below example.com (e.g. foo.example.com or bar.example.com).