1173812 - Update nsIEffectiveTLDService docs to talk about how the PSL works

Status: RESOLVED FIXED

(Developer Documentation Graveyard :: General, defect)

Description

[Mike Kaply [:mkaply]]

Gerv, 

Can you please update:

https://developer.mozilla.org/en-US/docs/Mozilla/Tech/XPCOM/Reference/Interface/nsIEffectiveTLDService#getPublicSuffix%28%29

To have some more detailed information?

In particular:

[09:56am] mkaply: OK, dumb question. Why does the effective eTLD.getPublicSuffixFromHost for “a.b.c.thisisnotadomain” return thisisnotadomain instead of null? Is there any API that can be used to validate domains against the base domain list?
[10:00am] gerv: mkaply: Answer:
[10:01am] gerv: because the Public Suffix List algorithm has an implicit "*" rule.
[10:01am] gerv: So, if you ask for the public suffix of "foo.intranet"
[10:01am] mastizada1 left the chat room. (Ping timeout: 121 seconds)
[10:01am] gerv: the answer is "intranet".
[10:01am] gerv: This is used e.g. for cookie setting, or base domain highlighting.
[10:01am] mkaply: gerv: Is there anyway to avoid that rule? We should have a flag or something.
[10:01am] mkaply: Chrome doesn’t do that
[10:01am] gerv: Well indeed,
[10:01am] gerv: and it causes problems.
[10:02am] gerv: Particularly if you are using a list which is not current.
[10:02am] gerv: So say someone inserts ".flowers" as a TLD in the DNS.
[10:02am] gerv: Chrome uses the PSL to determine what's a search and what's a domain name
[10:02am] gerv: type in "mum.flowers" and you'll get a search, not a website
[10:02am] gerv: That's bad.
[10:02am] gerv: Which is why the PSL is not recommended for such uses.
[10:02am] gerv: Given the flux in the TLD space,
[10:03am] gerv: and the existence of intranets, it is not recommended that software hard-codes what is and what is not a valid domain.
[10:03am] gerv: Intranets may or may not use private names,
[10:03am] gerv: and they may use names which were private when assigned but, due to flux in the TLD space, are now also

Comment 1

[Gervase Markham [:gerv]]

Added some notes at the top. Feel like reviewing? :-)

Gerv

Comment 2

[Mike Kaply [:mkaply]]

That's awesome.