-- XEP-0356 (Privileged Entity)

-- Copyright (C) 2015-2022 Jérôme Poisson

--

-- This module is MIT/X11 licensed. Please see the

-- COPYING file in the source package for more information.

--

-- Some parts come from mod_remote_roster (module by Waqas Hussain and Kim Alvefur, see https://code.google.com/p/prosody-modules/)

-- TODO: manage external <presence/> (for "roster" presence permission) when the account with the roster is offline

local jid = require("util.jid")

local set = require("util.set")

local st = require("util.stanza")

local roster_manager = require("core.rostermanager")

local usermanager_user_exists = require "core.usermanager".user_exists

local hosts = prosody.hosts

local full_sessions = prosody.full_sessions

local priv_session = module:shared("/*/privilege/session")

if priv_session.connected_cb == nil then

    -- set used to have connected event listeners

    -- which allows a host to react on events from

    -- other hosts

    priv_session.connected_cb = set.new()

end

local connected_cb = priv_session.connected_cb

-- the folowing sets are used to forward presence stanza

-- the folowing sets are used to forward presence stanza

local presence_man_ent = set.new()

local presence_roster = set.new()

local _ALLOWED_ROSTER = set.new({'none', 'get', 'set', 'both'})

local _ROSTER_GET_PERM = set.new({'get', 'both'})

local _ROSTER_SET_PERM = set.new({'set', 'both'})

local _ALLOWED_MESSAGE = set.new({'none', 'outgoing'})

local _ALLOWED_PRESENCE = set.new({'none', 'managed_entity', 'roster'})

local _PRESENCE_MANAGED = set.new({'managed_entity', 'roster'})

local _TO_CHECK = {roster=_ALLOWED_ROSTER, message=_ALLOWED_MESSAGE, presence=_ALLOWED_PRESENCE}

local _PRIV_ENT_NS = 'urn:xmpp:privilege:2'

local _FORWARDED_NS = 'urn:xmpp:forward:0'

local _MODULE_HOST = module:get_host()

module:log("debug", "Loading privileged entity module ")

--> Permissions management <--

local config_priv = module:get_option("privileged_entities", {})

local function get_session_privileges(session, host)

    if not session.privileges then return nil end

    return session.privileges[host]

end

local function advertise_perm(session, to_jid, perms)

    -- send <message/> stanza to advertise permissions

    -- as expained in § 4.2

    local message = st.message({from=module.host, to=to_jid})

                      :tag("privilege", {xmlns=_PRIV_ENT_NS})

    for _, perm in pairs({'roster', 'message', 'presence'}) do

        if perms[perm] then

            message:tag("perm", {access=perm, type=perms[perm]}):up()

        end

    end

    local iq_perm = perms["iq"]

    if iq_perm ~= nil then

        message:tag("perm", {access="iq"})

        for namespace, ns_perm in pairs(iq_perm) do

                local perm_type

                if ns_perm.set and ns_perm.get then

                    perm_type = "both"

                elseif ns_perm.set then

                    perm_type = "set"

                elseif ns_perm.get then

                    perm_type = "get"

                else

                    perm_type = nil

                end

                message:tag("namespace", {ns=namespace, type=perm_type})

        end

    end

    session.send(message)

end

local function set_presence_perm_set(to_jid, perms)

    -- fill the presence sets according to perms

    if _PRESENCE_MANAGED:contains(perms.presence) then

        presence_man_ent:add(to_jid)

    end

    if perms.presence == 'roster' then

        presence_roster:add(to_jid)

    end

end

local function advertise_presences(session, to_jid, perms)

    -- send presence status for already connected entities

    -- as explained in § 7.1

    -- people in roster are probed only for active sessions

    -- TODO: manage roster load for inactive sessions

    if not perms.presence then return; end

    local to_probe = {}

    for _, user_session in pairs(full_sessions) do

        if user_session.presence and _PRESENCE_MANAGED:contains(perms.presence) then

            local presence = st.clone(user_session.presence)

            presence.attr.to = to_jid

            module:log("debug", "sending current presence for "..tostring(user_session.full_jid))

            session.send(presence)

        end

        if perms.presence == "roster" then

            -- we reset the cache to avoid to miss a presence that just changed

            priv_session.last_presence = nil

            if user_session.roster then

                local bare_jid = jid.bare(user_session.full_jid)

                for entity, item in pairs(user_session.roster) do

                    if entity~=false and entity~="pending" and (item.subscription=="both" or item.subscription=="to") then

                        local _, host = jid.split(entity)

                        if not hosts[host] then -- we don't probe jid from hosts we manage

                            -- using a table with entity as key avoid probing several time the same one

                            to_probe[entity] = bare_jid

                        end

                    end

                end

            end

        end

    end

    -- now we probe peoples for "roster" presence permission

    for probe_to, probe_from in pairs(to_probe) do

        module:log("debug", "probing presence for %s (on behalf of %s)", tostring(probe_to), tostring(probe_from))

        local probe = st.presence({from=probe_from, to=probe_to, type="probe"})

        prosody.core_route_stanza(nil, probe)

    end

end

local function on_auth(event)

    -- Check if entity is privileged according to configuration,

    -- and set session.privileges accordingly

    local session = event.session

    local bare_jid = jid.join(session.username, session.host)

    if not session.privileges then

        session.privileges = {}

    end

    local conf_ent_priv = config_priv[bare_jid]

    local ent_priv = {}

    if conf_ent_priv ~= nil then

        module:log("debug", "Entity is privileged")

        for perm_type, allowed_values in pairs(_TO_CHECK) do

            local value = conf_ent_priv[perm_type]

            if value ~= nil then

                if not allowed_values:contains(value) then

                    module:log('warn', 'Invalid value for '..perm_type..' privilege: ['..value..']')

                    module:log('warn', 'Setting '..perm_type..' privilege to none')

                    ent_priv[perm_type] = nil

                elseif value == 'none' then

                    ent_priv[perm_type] = nil

                else

                    ent_priv[perm_type] = value

                end

            else

                ent_priv[perm_type] = nil

            end

        end

        -- extra checks for presence permission

        if ent_priv.presence == 'roster' and not _ROSTER_GET_PERM:contains(ent_priv.roster) then

            module:log("warn", "Can't allow roster presence privilege without roster \"get\" privilege")

            module:log("warn", "Setting presence permission to none")

            ent_priv.presence = nil

        end

        -- iq permission

        local iq_perm_config = conf_ent_priv["iq"]

        if iq_perm_config ~= nil then

            local iq_perm = {}

            ent_priv["iq"] = iq_perm

            for ns, ns_perm_config in pairs(iq_perm_config) do

                iq_perm[ns] = {

                    ["get"] = ns_perm_config == "get" or ns_perm_config == "both",

                    ["set"] = ns_perm_config == "set" or ns_perm_config == "both"

                }

            end

        else

            ent_priv["iq"] = nil

        end

        if session.type == "component" then

            -- we send the message stanza only for component

            -- it will be sent at first <presence/> for other entities

            advertise_perm(session, bare_jid, ent_priv)

            set_presence_perm_set(bare_jid, ent_priv)

            advertise_presences(session, bare_jid, ent_priv)

        end

    end

    session.privileges[_MODULE_HOST] = ent_priv

end

local function on_presence(event)

    -- Permission are already checked at this point,

    -- we only advertise them to the entity

    local session = event.origin

    local session_privileges = get_session_privileges(session, _MODULE_HOST)

    if session_privileges then

        advertise_perm(session, session.full_jid, session_privileges)

        set_presence_perm_set(session.full_jid, session_privileges)

        advertise_presences(session, session.full_jid, session_privileges)

    end

end

local function on_component_auth(event)

    -- react to component-authenticated event from this host

    -- and call the on_auth methods from all other hosts

    -- needed for the component to get delegations advertising

    for callback in connected_cb:items() do

        callback(event)

    end

end

if module:get_host_type() ~= "component" then

    connected_cb:add(on_auth)

end

module:hook('authentication-success', on_auth)

module:hook('component-authenticated', on_component_auth)

module:hook('presence/initial', on_presence)

--> roster permission <--

-- get

module:hook("iq-get/bare/jabber:iq:roster:query", function(event)

    local session, stanza = event.origin, event.stanza

    if not stanza.attr.to then

        -- we don't want stanzas addressed to /self

        return

    end

    local node, host = jid.split(stanza.attr.to)

    local session_privileges = get_session_privileges(session, host)

    if session_privileges and _ROSTER_GET_PERM:contains(session_privileges.roster) then

        module:log("debug", "Roster get from allowed privileged entity received")

        -- following code is adapted from mod_remote_roster

        local roster = roster_manager.load_roster(node, host)

        local reply = st.reply(stanza):query("jabber:iq:roster")

        for entity_jid, item in pairs(roster) do

            if entity_jid and entity_jid ~= "pending" then

                reply:tag("item", {

                    jid = entity_jid,

                    subscription = item.subscription,

                    ask = item.ask,

                    name = item.name,

                })

                for group in pairs(item.groups) do

                    reply:tag("group"):text(group):up()

                end

                reply:up(); -- move out from item

            end

        end

        -- end of code adapted from mod_remote_roster

        session.send(reply)

    else

        module:log("warn", "Entity "..tostring(session.full_jid).." try to get roster without permission")

        session.send(st.error_reply(stanza, 'auth', 'forbidden'))

    end

    return true

end)

-- set

module:hook("iq-set/bare/jabber:iq:roster:query", function(event)

    local session, stanza = event.origin, event.stanza

    if not stanza.attr.to then

        -- we don't want stanzas addressed to /self

        return

    end

    local from_node, from_host = jid.split(stanza.attr.to)

    local session_privileges = get_session_privileges(session, from_host)

    if session_privileges and _ROSTER_SET_PERM:contains(session_privileges.roster) then

        module:log("debug", "Roster set from allowed privileged entity received")

        -- following code is adapted from mod_remote_roster

        if not(usermanager_user_exists(from_node, from_host)) then return; end

        local roster = roster_manager.load_roster(from_node, from_host)

        if not(roster) then return; end

        local query = stanza.tags[1]

        for _, item in ipairs(query.tags) do

            if item.name == "item"

                and item.attr.xmlns == "jabber:iq:roster" and item.attr.jid

                    -- Protection against overwriting roster.pending, until we move it

                and item.attr.jid ~= "pending" then

                local item_jid = jid.prep(item.attr.jid)

                local _, host, resource = jid.split(item_jid)

                if not resource then

                    if item_jid ~= stanza.attr.to then -- not self-item_jid

                        if item.attr.subscription == "remove" then

                            local r_item = roster[item_jid]

                            if r_item then

                                roster[item_jid] = nil

                                if roster_manager.save_roster(from_node, from_host, roster) then

                                    session.send(st.reply(stanza))

                                    roster_manager.roster_push(from_node, from_host, item_jid)

                                else

                                    roster[item_jid] = item

                                    session.send(st.error_reply(stanza, "wait", "internal-server-error", "Unable to save roster"))

                                end

                            else

                                session.send(st.error_reply(stanza, "modify", "item-not-found"))

                            end

                        else

                            local subscription = item.attr.subscription

                            if subscription ~= "both" and subscription ~= "to" and subscription ~= "from" and subscription ~= "none" then -- TODO error on invalid

                                subscription = roster[item_jid] and roster[item_jid].subscription or "none"

                            end

                            local r_item = {name = item.attr.name, groups = {}}

                            if r_item.name == "" then r_item.name = nil; end

                            r_item.subscription = subscription

                            if subscription ~= "both" and subscription ~= "to" then

                                r_item.ask = roster[item_jid] and roster[item_jid].ask

                            end

                            for _, child in ipairs(item) do

                                if child.name == "group" then

                                    local text = table.concat(child)

                                    if text and text ~= "" then

                                        r_item.groups[text] = true

                                    end

                                end

                            end

                            local olditem = roster[item_jid]

                            roster[item_jid] = r_item

                            if roster_manager.save_roster(from_node, from_host, roster) then -- Ok, send success

                                session.send(st.reply(stanza))

                                -- and push change to all resources

                                roster_manager.roster_push(from_node, from_host, item_jid)

                            else -- Adding to roster failed

                                roster[item_jid] = olditem

                                session.send(st.error_reply(stanza, "wait", "internal-server-error", "Unable to save roster"))

                            end

                        end

                    else -- Trying to add self to roster

                        session.send(st.error_reply(stanza, "cancel", "not-allowed"))

                    end

                else -- Invalid JID added to roster

                    module:log("warn", "resource: %s , host: %s", tostring(resource), tostring(host))

                    session.send(st.error_reply(stanza, "modify", "bad-request")); -- FIXME what's the correct error?

                end

            else -- Roster set didn't include a single item, or its name wasn't  'item'

                session.send(st.error_reply(stanza, "modify", "bad-request"))

            end

        end -- for loop end

        -- end of code adapted from mod_remote_roster

    else -- The permission is not granted

        module:log("warn", "Entity "..tostring(session.full_jid).." try to set roster without permission")

        session.send(st.error_reply(stanza, 'auth', 'forbidden'))

    end

    return true

end)