urbit/pkg/arvo/app/link-proxy-hook.hoon

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:: link-proxy-hook: make local pages available to foreign ships
::
:: this is a "proxy" style hook, relaying foreign subscriptions into local
:: stores if permission conditions are met.
:: the patterns herein should one day be generalized into a proxy-hook lib.
::
:: this uses metadata-store to discover resources and their associated
:: groups. it sets the permission condition to be that a ship must be in a
:: group associated with the resource it's subscribing to.
:: we check this on-watch, but also subscribe to metadata & groups so that
:: we can kick subscriptions if needed (eg ship removed from group).
::
:: we deduplicate incoming subscriptions on the same path, ensuring we have
:: exactly one local subscription per unique incoming subscription path.
:: this comes at the cost of assuming that the store's initial response is
:: whatever's returned by the scry at that path, but perhaps that should
:: become part of the stores standard anyway.
::
:: when adding support for new paths, the only things you'll likely want
:: to touch are +permitted, +initial-response, & +kick-proxies.
::
/- group-store, *metadata-store
/+ *link, metadata, default-agent, verb, dbug
~% %link-proxy-hook-top ..is ~
|%
+$ state-0
$: %0
::TODO we use this to detect "first sub started" and "last sub left",
:: but can't we use [wex sup]:bowl for that?
active=(map path (set ship))
==
::
+$ card card:agent:gall
--
::
=| state-0
=* state -
::
%- agent:dbug
%+ verb |
^- agent:gall
=<
|_ =bowl:gall
+* this .
do ~(. +> bowl)
def ~(. (default-agent this %&) bowl)
::
++ on-init
^- (quip card _this)
:_ this
~[watch-groups:do watch-metadata:do]
::
++ on-save !>(state)
++ on-load
|= old=vase
^- (quip card _this)
[~ this(state !<(state-0 old))]
::
++ on-watch
|= =path
^- (quip card _this)
:: the local ship should just use link-store directly
::TODO do we want to allow this anyway, to avoid client-side target checks?
::
?< (team:title [our src]:bowl)
?> (permitted:do src.bowl path)
=^ cards state
(start-proxy:do src.bowl path)
[cards this]
::
++ on-leave
|= =path
^- (quip card _this)
=^ cards state
(stop-proxy:do src.bowl path)
[cards this]
::
++ on-agent
|= [=wire =sign:agent:gall]
^- (quip card _this)
?: ?=([%groups ~] wire)
=^ cards state
(take-groups-sign:do sign)
[cards this]
?: ?=([%proxy ^] wire)
=^ cards state
(handle-proxy-sign t.wire sign)
[cards this]
~| [dap.bowl %weird-wire wire]
!!
::
++ on-poke on-poke:def
++ on-peek on-peek:def
++ on-arvo on-arvo:def
++ on-fail on-fail:def
--
::
|_ =bowl:gall
+* md ~(. metadata bowl)
::
:: permissions
::
++ permitted
|= [who=ship =path]
^- ?
:: we only expose /local-pages and /annotations,
:: to ships in the groups associated with the resource.
:: (no url-specific annotations subscriptions, either.)
::
=/ target=(unit ^path)
?: ?=([%local-pages ^] path)
`t.path
?: ?=([%annotations ~ ^] path)
`t.t.path
~
?~ target |
~? !.^(? %gu (scot %p our.bowl) %metadata-store (scot %da now.bowl) ~)
%woah-md-s-not-booted ::TODO fallback if needed
%+ lien (groups-from-resource:md %link u.target)
|= =group-path
^- ?
=- (~(has in (fall - *group:group-store)) who)
%^ scry-for (unit group:group-store)
%group-store
group-path
::
++ kick-revoked-permissions
|= [=path who=(list ship)]
^- (list card)
%+ murn who
|= =ship
^- (unit card)
:: no need to remove to ourselves
::
?: =(our.bowl ship) ~
?: (permitted ship path) ~
`(kick-proxies ship path)
::
:: metadata subscription
::
++ watch-metadata
^- card
[%pass /metadata %agent [our.bowl %metadata-store] %watch /app-name/link]
::
++ take-metadata-sign
|= =sign:agent:gall
^- (quip card _state)
?- -.sign
%poke-ack ~|([dap.bowl %unexpected-poke-ack /metadata] !!)
%kick [[watch-metadata]~ state]
::
%watch-ack
?~ p.sign [~ state]
=/ =tank
:- %leaf
"{(trip dap.bowl)} failed subscribe to metadata store. very wrong!"
%- (slog tank u.p.sign)
[~ state]
::
%fact
=* mark p.cage.sign
=* vase q.cage.sign
?. ?=(%metadata-update mark)
~| [dap.bowl %unexpected-mark mark]
!!
%- handle-metadata-update
!<(metadata-update vase)
==
::
++ handle-metadata-update
|= upd=metadata-update
^- (quip card _state)
:_ state
?. ?=(%remove -.upd) ~
?> =(%link app-name.resource.upd)
:: if a group is no longer associated with a resource,
:: we need to re-check permissions for everyone in that group.
::
%+ kick-revoked-permissions
app-path.resource.upd
%~ tap in
=- (fall - *group:group-store)
%^ scry-for (unit group:group-store)
%group-store
group-path.upd
::
:: groups subscription
::TODO largely copied from link-listen-hook. maybe make a store-listener lib?
::
++ watch-groups
^- card
[%pass /groups %agent [our.bowl %group-store] %watch /all]
::
++ take-groups-sign
|= =sign:agent:gall
^- (quip card _state)
?- -.sign
%poke-ack ~|([dap.bowl %unexpected-poke-ack /groups] !!)
%kick [[watch-groups]~ state]
::
%watch-ack
?~ p.sign [~ state]
=/ =tank
:- %leaf
"{(trip dap.bowl)} failed subscribe to group store. very wrong!"
%- (slog tank u.p.sign)
[~ state]
::
%fact
=* mark p.cage.sign
=* vase q.cage.sign
?+ mark ~|([dap.bowl %unexpected-mark mark] !!)
%group-initial [~ state]
%group-update (handle-group-update !<(group-update:group-store vase))
==
==
::
++ handle-group-update
|= upd=group-update:group-store
^- (quip card _state)
:_ state
?. ?=(%remove -.upd) ~
:: if someone was removed from a group, find all link resources associated
:: with that group, then kick their subscriptions if they're no longer
::
%- zing
%+ turn (app-paths-from-group:md %link pax.upd)
|= =app-path
^- (list card)
%+ kick-revoked-permissions
app-path
~(tap in members.upd)
::
:: proxy subscriptions
::
++ kick-proxies
|= [who=ship =path]
^- card
=- [%give %kick - `who]
:~ [%local-pages path]
[%annotations %$ path]
==
::
++ handle-proxy-sign
|= [=wire =sign:agent:gall]
^- (quip card _state)
?- -.sign
%poke-ack ~|([dap.bowl %unexpected-poke-ack wire] !!)
%fact [[%give %fact ~[wire] cage.sign]~ state]
%kick [[(proxy-pass-link-store wire %watch wire)]~ state]
::
%watch-ack
?~ p.sign [~ state]
=/ =tank
:- %leaf
"{(trip dap.bowl)} failed subscribe to link-store. very wrong!"
%- (slog tank u.p.sign)
[~ state]
==
::
++ proxy-pass-link-store
|= [=path =task:agent:gall]
^- card
:* %pass
[%proxy path]
%agent
[our.bowl %link-store]
task
==
::
++ initial-response
|= =path
^- card
=; =initial
[%give %fact ~ %link-initial !>(initial)]
?+ path !!
[%local-pages ^]
[%local-pages (scry-for (map ^path pages) %link-store path)]
::
[%annotations %$ ^]
[%annotations (scry-for (per-path-url notes) %link-store path)]
==
::
++ start-proxy
|= [who=ship =path]
^- (quip card _state)
:_ state(active (~(put ju active) path who))
:_ ~
:: if we already have a local subscription open,
::
?. =(~ (~(get ju active) path))
:: gather the initial response ourselves, and send that.
::
(initial-response path)
:: else, open a local subscription,
:: sending outward its initial response when we hear it.
::
(proxy-pass-link-store path %watch path)
::
++ stop-proxy
|= [who=ship =path]
^- (quip card _state)
=. active (~(del ju active) path who)
:_ state
:: if there are still subscriptions remaining, do nothing.
::
?. =(~ (~(get ju active) path)) ~
:: else, close the local subscription.
::
[(proxy-pass-link-store path %leave ~)]~
::
:: helpers
::
++ scry-for
|* [=mold =app-name =path]
.^ mold
%gx
(scot %p our.bowl)
app-name
(scot %da now.bowl)
(snoc `^path`path %noun)
==
--