[Haskell-cafe] Contributing to http-conduit

[Michael Snoyman]

Just an FYI for everyone: Myles sent an (incredibly thorough) pull
request to handle cookies:

https://github.com/snoyberg/http-conduit/pull/13

Thanks!

On Sun, Feb 5, 2012 at 8:20 AM, Myles C. Maxfield
<myles.maxfield at gmail.com> wrote:
> 1. The spec defines a grammar for the attributes. They're in uppercase.
> 2. Yes - 1.3 is the first version that lists DiffTime as an instance of
> RealFrac (so I can use the 'floor' function to pull out the number of
> seconds to render it)
> 3. I'll see what I can do.
>
> --Myles
>
>
> On Sat, Feb 4, 2012 at 9:06 PM, Michael Snoyman <michael at snoyman.com> wrote:
>>
>> Looks good, a few questions/requests:
>>
>> 1. Is there a reason to upper-case all the attributes?
>> 2. Is the time >= 1.3 a requirements? Because that can cause a lot of
>> trouble for people.
>> 3. Can you send the patch as a Github pull request? It's easier to
>> track that way.
>>
>> Michael
>>
>> On Sat, Feb 4, 2012 at 1:21 AM, Myles C. Maxfield
>> <myles.maxfield at gmail.com> wrote:
>> > Here is the patch to Web.Cookie. I didn't modify the tests at all
>> > because
>> > they were already broken - they looked like they hadn't been updated
>> > since
>> > SetCookie only had 5 parameters. I did verify by hand that the patch
>> > works,
>> > though.
>> >
>> > Thanks,
>> > Myles
>> >
>> >
>> > On Thu, Feb 2, 2012 at 11:26 PM, Myles C. Maxfield
>> > <myles.maxfield at gmail.com> wrote:
>> >>
>> >> Alright, I'll make a small patch that adds 2 fields to SetCookie:
>> >> setCookieMaxAge :: Maybe DiffTime
>> >> setCookieSecureOnly :: Bool
>> >>
>> >> I've also gotten started on those cookie functions. I'm currently
>> >> writing
>> >> tests for them.
>> >>
>> >> @Chris: The best advice I can give is that Chrome (what I'm using as a
>> >> source on all this) has the data baked into a .cc file. However, they
>> >> have
>> >> directions in a README and a script which will parse the list and
>> >> generate
>> >> that source file. I recommend doing this. That way, the Haskell module
>> >> would
>> >> have 2 source files: one file that reads the list and generates the
>> >> second
>> >> file, which is a very large source file that contains each element in
>> >> the
>> >> list. The list should export `elem`-type queries. I'm not quite sure
>> >> how to
>> >> handle wildcards that appear in the list - that part is up to you.
>> >> Thanks
>> >> for helping out with this :]
>> >>
>> >> --Myles
>> >>
>> >>
>> >> On Thu, Feb 2, 2012 at 10:53 PM, Michael Snoyman <michael at snoyman.com>
>> >> wrote:
>> >>>
>> >>> Looks good to me too. I agree with Aristid: let's make the change to
>> >>> cookie itself. Do you want to send a pull request? I'm also
>> >>> considering making the SetCookie constructor hidden like we have for
>> >>> Request, so that if in the future we realize we need to add some other
>> >>> settings, it doesn't break the API.
>> >>>
>> >>> Chris: I would recommend compiling it into the module. Best bet would
>> >>> likely being converting the source file to Haskell source.
>> >>>
>> >>> Michael
>> >>>
>> >>> On Fri, Feb 3, 2012 at 6:32 AM, Myles C. Maxfield
>> >>> <myles.maxfield at gmail.com> wrote:
>> >>> > Alright. After reading the spec, I have these questions / concerns:
>> >>> >
>> >>> > The spec supports the "Max-Age" cookie attribute, which Web.Cookies
>> >>> > doesn't.
>> >>> >
>> >>> > I see two possible solutions to this. The first is to have
>> >>> > parseSetCookie
>> >>> > take a UTCTime as an argument which will represent the current time
>> >>> > so
>> >>> > it
>> >>> > can populate the setCookieExpires field by adding the Max-Age
>> >>> > attribute
>> >>> > to
>> >>> > the current time. Alternatively, that function can return an IO
>> >>> > SetCookie so
>> >>> > it can ask for the current time by itself (which I think is inferior
>> >>> > to
>> >>> > taking the current time as an argument). Note that the spec says to
>> >>> > prefer
>> >>> > Max-Age over Expires.
>> >>> > Add a field to SetCookie of type Maybe DiffTime which represents the
>> >>> > Max-Age
>> >>> > attribute
>> >>> >
>> >>> > Cookie code should be aware of the Public Suffix List as a part of
>> >>> > its
>> >>> > domain verification. The cookie code only needs to be able to tell
>> >>> > if a
>> >>> > specific string is in the list (W.Ascii -> Bool)
>> >>> >
>> >>> > I propose making an entirely unrelated package, public-suffix-list,
>> >>> > with a
>> >>> > module Network.PublicSuffixList, which will expose this function, as
>> >>> > well as
>> >>> > functions about parsing the list itself. Thoughts?
>> >>> >
>> >>> > Web.Cookie doesn't have a "secure-only" attribute. Adding one in is
>> >>> > straightforward enough.
>> >>> > The spec describes cookies as a property of HTTP, not of the World
>> >>> > Wide
>> >>> > Web.
>> >>> > Perhaps "Web.Cookie" should be renamed? Just a thought; it doesn't
>> >>> > really
>> >>> > matter to me.
>> >>> >
>> >>> > As for Network.HTTP.Conduit.Cookie, the spec describes in section
>> >>> > 5.3
>> >>> > "Storage Model" what fields a Cookie has. Here is my proposal for
>> >>> > the
>> >>> > functions it will expose:
>> >>> >
>> >>> > receiveSetCookie :: SetCookie -> Req.Request m -> UTCTime -> Bool ->
>> >>> > CookieJar -> CookieJar
>> >>> >
>> >>> > Runs the algorithm described in section 5.3 "Storage Model"
>> >>> > The UTCTime is the current-time, the Bool is whether or not the
>> >>> > caller
>> >>> > is an
>> >>> > HTTP-based API (as opposed to JavaScript or anything else)
>> >>> >
>> >>> > updateCookieJar :: Res.Response a -> Req.Request m -> UTCTime ->
>> >>> > CookieJar
>> >>> > -> (CookieJar, Res.Response a)
>> >>> >
>> >>> > Applies "receiveSetCookie" to a Response. The output CookieJar is
>> >>> > stripped
>> >>> > of any Set-Cookie headers.
>> >>> > Specifies "True" for the Bool in receiveSetCookie
>> >>> >
>> >>> > computeCookieString :: Req.Request m -> CookieJar -> UTCTime -> Bool
>> >>> > ->
>> >>> > (W.Ascii, CookieJar)
>> >>> >
>> >>> > Runs the algorithm described in section 5.4 "The Cookie Header"
>> >>> > The UTCTime and Bool are the same as in receiveSetCookie
>> >>> >
>> >>> > insertCookiesIntoRequest :: Req.Request m -> CookieJar -> UTCTime ->
>> >>> > (Req.Request m, CookieJar)
>> >>> >
>> >>> > Applies "computeCookieString" to a Request. The output cookie jar
>> >>> > has
>> >>> > updated last-accessed-times.
>> >>> > Specifies "True" for the Bool in computeCookieString
>> >>> >
>> >>> > evictExpiredCookies :: CookieJar -> UTCTime -> CookieJar
>> >>> >
>> >>> > Runs the algorithm described in the last part of section 5.3
>> >>> > "Storage
>> >>> > Model"
>> >>> >
>> >>> > This will make the relevant part of 'http' look like:
>> >>> >
>> >>> >     go count req'' cookie_jar'' = do
>> >>> >         now <- liftIO $ getCurrentTime
>> >>> >         let (req', cookie_jar') = insertCookiesIntoRequest req''
>> >>> > (evictExpiredCookies cookie_jar'' now) now
>> >>> >         res' <- httpRaw req' manager
>> >>> >         let (cookie_jar, res) = updateCookieJar res' req' now
>> >>> > cookie_jar'
>> >>> >         case getRedirectedRequest req' (responseHeaders res)
>> >>> > (W.statusCode
>> >>> > (statusCode res)) of
>> >>> >             Just req -> go (count - 1) req cookie_jar
>> >>> >             Nothing -> return res
>> >>> >
>> >>> > I plan to not allow for a user-supplied cookieFilter function. If
>> >>> > they
>> >>> > want
>> >>> > that functionality, they can re-implement the redirection-following
>> >>> > logic.
>> >>> >
>> >>> > Any thoughts on any of this?
>> >>> >
>> >>> > Thanks,
>> >>> > Myles
>> >>> >
>> >>> > On Wed, Feb 1, 2012 at 5:19 PM, Myles C. Maxfield
>> >>> > <myles.maxfield at gmail.com>
>> >>> > wrote:
>> >>> >>
>> >>> >> Nope. I'm not. The RFC is very explicit about how to handle
>> >>> >> cookies.
>> >>> >> As
>> >>> >> soon as I'm finished making sense of it (in terms of Haskell) I'll
>> >>> >> send
>> >>> >> another proposal email.
>> >>> >>
>> >>> >> On Feb 1, 2012 3:25 AM, "Michael Snoyman" <michael at snoyman.com>
>> >>> >> wrote:
>> >>> >>>
>> >>> >>> You mean you're *not* making this proposal?
>> >>> >>>
>> >>> >>> On Wed, Feb 1, 2012 at 7:30 AM, Myles C. Maxfield
>> >>> >>> <myles.maxfield at gmail.com> wrote:
>> >>> >>> > Well, this is embarrassing. Please disregard my previous email.
>> >>> >>> > I
>> >>> >>> > should
>> >>> >>> > learn to read the RFC *before* submitting proposals.
>> >>> >>> >
>> >>> >>> > --Myles
>> >>> >>> >
>> >>> >>> >
>> >>> >>> > On Tue, Jan 31, 2012 at 6:37 PM, Myles C. Maxfield
>> >>> >>> > <myles.maxfield at gmail.com> wrote:
>> >>> >>> >>
>> >>> >>> >> Here are my initial ideas about supporting cookies. Note that
>> >>> >>> >> I'm
>> >>> >>> >> using
>> >>> >>> >> Chrome for ideas since it's open source.
>> >>> >>> >>
>> >>> >>> >> Network/HTTP/Conduit/Cookies.hs file
>> >>> >>> >> Exporting the following symbols:
>> >>> >>> >>
>> >>> >>> >> type StuffedCookie = SetCookie
>> >>> >>> >>
>> >>> >>> >> A regular SetCookie can have Nothing for its Domain and Path
>> >>> >>> >> attributes. A
>> >>> >>> >> StuffedCookie has to have these fields set.
>> >>> >>> >>
>> >>> >>> >> type CookieJar = [StuffedCookie]
>> >>> >>> >>
>> >>> >>> >> Chrome's cookie jar is implemented as (the C++ equivalent of)
>> >>> >>> >> Map
>> >>> >>> >> W.Ascii
>> >>> >>> >> StuffedCookie. The key is the "eTLD+1" of the domain, so
>> >>> >>> >> lookups
>> >>> >>> >> for
>> >>> >>> >> all
>> >>> >>> >> cookies for a given domain are fast.
>> >>> >>> >> I think I'll stay with just a list of StuffedCookies just to
>> >>> >>> >> keep
>> >>> >>> >> it
>> >>> >>> >> simple. Perhaps a later revision can implement the faster map.
>> >>> >>> >>
>> >>> >>> >> getRelevantCookies :: Request m -> CookieJar -> UTCTime ->
>> >>> >>> >> (CookieJar,
>> >>> >>> >> Cookies)
>> >>> >>> >>
>> >>> >>> >> Gets all the cookies from the cookie jar that should be set for
>> >>> >>> >> the
>> >>> >>> >> given
>> >>> >>> >> Request.
>> >>> >>> >> The time argument is whatever "now" is (it's pulled out of the
>> >>> >>> >> function so
>> >>> >>> >> the function can remain pure and easily testable)
>> >>> >>> >> The function will also remove expired cookies from the cookie
>> >>> >>> >> jar
>> >>> >>> >> (given
>> >>> >>> >> what "now" is) and return the filtered cookie jar
>> >>> >>> >>
>> >>> >>> >> putRelevantCookies :: Request m -> CookieJar -> [StuffedCookie]
>> >>> >>> >> ->
>> >>> >>> >> CookieJar
>> >>> >>> >>
>> >>> >>> >> Insert cookies from a server response into the cookie jar.
>> >>> >>> >> The first argument is only used for checking to see which
>> >>> >>> >> cookies
>> >>> >>> >> are
>> >>> >>> >> valid (which cookies match the requested domain, etc, so
>> >>> >>> >> site1.com
>> >>> >>> >> can't set
>> >>> >>> >> a cookie for site2.com)
>> >>> >>> >>
>> >>> >>> >> stuffCookie :: Request m -> SetCookie -> StuffedCookie
>> >>> >>> >>
>> >>> >>> >> If the SetCookie's fields are Nothing, fill them in given the
>> >>> >>> >> Request
>> >>> >>> >> from
>> >>> >>> >> which it originated
>> >>> >>> >>
>> >>> >>> >> getCookies :: Response a -> ([SetCookie], Response a)
>> >>> >>> >>
>> >>> >>> >> Pull cookies out of a server response. Return the response with
>> >>> >>> >> the
>> >>> >>> >> Set-Cookie headers filtered out
>> >>> >>> >>
>> >>> >>> >> putCookies :: Request a -> Cookies -> Request a
>> >>> >>> >>
>> >>> >>> >> A wrapper around renderCookies. Inserts some cookies into a
>> >>> >>> >> request.
>> >>> >>> >> Doesn't overwrite cookies that are already set in the request
>> >>> >>> >>
>> >>> >>> >> These functions will be exported from Network.HTTP.Conduit as
>> >>> >>> >> well, so
>> >>> >>> >> callers can use them to re-implement redirection chains
>> >>> >>> >> I won't implement a cookie filtering function (like what
>> >>> >>> >> Network.Browser
>> >>> >>> >> has)
>> >>> >>> >>
>> >>> >>> >> If you want to have arbitrary handling of cookies, re-implement
>> >>> >>> >> redirection following. It's not very difficult if you use the
>> >>> >>> >> API
>> >>> >>> >> provided,
>> >>> >>> >> and the 'http' function is open source so you can use that as a
>> >>> >>> >> reference.
>> >>> >>> >>
>> >>> >>> >> I will implement the functions according to RFC 6265
>> >>> >>> >> I will also need to write the following functions. Should they
>> >>> >>> >> also be
>> >>> >>> >> exported?
>> >>> >>> >>
>> >>> >>> >> canonicalizeDomain :: W.Ascii -> W.Ascii
>> >>> >>> >>
>> >>> >>> >> turns "..a.b.c..d.com..." to "a.b.c.d.com"
>> >>> >>> >> Technically necessary for domain matching (Chrome does it)
>> >>> >>> >> Perhaps unnecessary for a first pass? Perhaps we can trust
>> >>> >>> >> users
>> >>> >>> >> for
>> >>> >>> >> now?
>> >>> >>> >>
>> >>> >>> >> domainMatches :: W.Ascii -> W.Ascii -> Maybe W.Ascii
>> >>> >>> >>
>> >>> >>> >> Does the first domain match against the second domain?
>> >>> >>> >> If so, return the prefix of the first that isn't in the second
>> >>> >>> >>
>> >>> >>> >> pathMatches :: W.Ascii -> W.Ascii -> Bool
>> >>> >>> >>
>> >>> >>> >> Do the paths match?
>> >>> >>> >>
>> >>> >>> >> In order to implement domain matching, I have to have knowledge
>> >>> >>> >> of
>> >>> >>> >> the Public Suffix List so I know that sub1.sub2.pvt.k12.wy.us
>> >>> >>> >> can
>> >>> >>> >> set
>> >>> >>> >> a
>> >>> >>> >> cookie for sub2.pvt.k12.wy.us but not for k12.wy.us (because
>> >>> >>> >> pvt.k12.wy.us
>> >>> >>> >> is a "suffix"). There are a variety of ways to implement this.
>> >>> >>> >>
>> >>> >>> >> As far as I can tell, Chrome does it by using a script (which a
>> >>> >>> >> human
>> >>> >>> >> periodically runs) which parses the list at creates a .cc file
>> >>> >>> >> that is
>> >>> >>> >> included in the build.
>> >>> >>> >>
>> >>> >>> >> I might be wrong about the execution of the script; it might be
>> >>> >>> >> a
>> >>> >>> >> build
>> >>> >>> >> step. If it is a build step, however, it is suspicious that a
>> >>> >>> >> build
>> >>> >>> >> target
>> >>> >>> >> would try to download a file...
>> >>> >>> >>
>> >>> >>> >> Any more elegant ideas?
>> >>> >>> >>
>> >>> >>> >> Feedback on any/all of the above would be very helpful before I
>> >>> >>> >> go
>> >>> >>> >> off
>> >>> >>> >> into the weeds on this project.
>> >>> >>> >>
>> >>> >>> >> Thanks,
>> >>> >>> >> Myles C. Maxfield
>> >>> >>> >>
>> >>> >>> >> On Sat, Jan 28, 2012 at 8:17 PM, Michael Snoyman
>> >>> >>> >> <michael at snoyman.com>
>> >>> >>> >> wrote:
>> >>> >>> >>>
>> >>> >>> >>> Thanks, looks great! I've merged it into the Github tree.
>> >>> >>> >>>
>> >>> >>> >>> On Sat, Jan 28, 2012 at 8:36 PM, Myles C. Maxfield
>> >>> >>> >>> <myles.maxfield at gmail.com> wrote:
>> >>> >>> >>> > Ah, yes, you're completely right. I completely agree that
>> >>> >>> >>> > moving
>> >>> >>> >>> > the
>> >>> >>> >>> > function into the Maybe monad increases readability. This
>> >>> >>> >>> > kind
>> >>> >>> >>> > of
>> >>> >>> >>> > function
>> >>> >>> >>> > is what the Maybe monad was designed for.
>> >>> >>> >>> >
>> >>> >>> >>> > Here is a revised patch.
>> >>> >>> >>> >
>> >>> >>> >>> >
>> >>> >>> >>> > On Sat, Jan 28, 2012 at 8:28 AM, Michael Snoyman
>> >>> >>> >>> > <michael at snoyman.com>
>> >>> >>> >>> > wrote:
>> >>> >>> >>> >>
>> >>> >>> >>> >> On Sat, Jan 28, 2012 at 1:20 AM, Myles C. Maxfield
>> >>> >>> >>> >> <myles.maxfield at gmail.com> wrote:
>> >>> >>> >>> >> > the fromJust should never fail, beceause of the guard
>> >>> >>> >>> >> > statement:
>> >>> >>> >>> >> >
>> >>> >>> >>> >> >     | 300 <= code && code < 400 && isJust l'' && isJust
>> >>> >>> >>> >> > l' =
>> >>> >>> >>> >> > Just $
>> >>> >>> >>> >> > req
>> >>> >>> >>> >> >
>> >>> >>> >>> >> > Because of the order of the && operators, it will only
>> >>> >>> >>> >> > evaluate
>> >>> >>> >>> >> > fromJust
>> >>> >>> >>> >> > after it makes sure that the argument isJust. That
>> >>> >>> >>> >> > function
>> >>> >>> >>> >> > in
>> >>> >>> >>> >> > particular
>> >>> >>> >>> >> > shouldn't throw any exceptions - it should only return
>> >>> >>> >>> >> > Nothing.
>> >>> >>> >>> >> >
>> >>> >>> >>> >> > Knowing that, I don't quite think I understand what your
>> >>> >>> >>> >> > concern
>> >>> >>> >>> >> > is.
>> >>> >>> >>> >> > Can
>> >>> >>> >>> >> > you
>> >>> >>> >>> >> > elaborate?
>> >>> >>> >>> >>
>> >>> >>> >>> >> You're right, but I had to squint really hard to prove to
>> >>> >>> >>> >> myself
>> >>> >>> >>> >> that
>> >>> >>> >>> >> you're right. That's the kind of code that could easily be
>> >>> >>> >>> >> broken
>> >>> >>> >>> >> in
>> >>> >>> >>> >> future updates by an unwitting maintainer (e.g., me). To
>> >>> >>> >>> >> protect
>> >>> >>> >>> >> the
>> >>> >>> >>> >> world from me, I'd prefer if the code didn't have the
>> >>> >>> >>> >> fromJust.
>> >>> >>> >>> >> This
>> >>> >>> >>> >> might be a good place to leverage the Monad instance of
>> >>> >>> >>> >> Maybe.
>> >>> >>> >>> >>
>> >>> >>> >>> >> Michael
>> >>> >>> >>> >
>> >>> >>> >>> >
>> >>> >>> >>
>> >>> >>> >>
>> >>> >>> >
>> >>> >
>> >>> >
>> >>
>> >>
>> >
>
>