mod_delegation

Introduction

Namespace Delegation is an extension which allows server to delegate some features handling to an entity/component. Typical use case is an external PEP service, but it can be used more generally when your preferred server lack one internal feature, and you found an external component which can do it.

Details

You can have all the details by reading the XEP-0355. Only the admin mode is implemented so far.

Usage

To use the module, like usual add “delegation” to your modules_enabled. Note that if you use it with a local component, you also need to activate the module in your component section:

modules_enabled = {
        [...]

        "delegation";
}

[...]

Component "youcomponent.yourdomain.tld"
    component_secret = "yourpassword"
    modules_enabled = {"delegation"}

then specify delegated namespaces in your host section like that:

VirtualHost "yourdomain.tld"

    delegations = {
        ["urn:xmpp:mam:2"] = {
            filtering = {"node"};
            jid = "pubsub.yourdomain.tld";
        },
        ["http://jabber.org/protocol/pubsub"] = {
            jid = "pubsub.yourdomain.tld";
        },
        ["http://jabber.org/protocol/pubsub#owner"] = {
            jid = "pubsub.yourdomain.tld";
        },
        ["urn:xmpp:delegation:2:bare:disco#info:*"] = {
            jid = "pubsub.yourdomain.tld";
        },
        ["urn:xmpp:delegation:2:bare:disco#items:*"] = {
            jid = "pubsub.yourdomain.tld";
        },

    }

Here all MAM requests with a “node” attribute (i.e. all MAM pubsub request) will be delegated to pubsub.yourdomain.tld. Similarly, all pubsub request to the host (i.e. the PEP requests) will be delegated to pubsub.yourdomain.tld. Check the XEP for the meaning of “urn:xmpp:delegation:2:bare:disco#info:” and ”urn:xmpp:delegation:2:bare:disco#items:”.

/! Be extra careful when you give a delegation to an entity/component, it’s a powerful access, only do it if you absolutely trust the component/entity, and you know where the software is coming from

Configuration

The configuration is done with a table which map delegated namespace to namespace data. Namespace data MUST have a jid (in the form jid = “delegated@domain.tld”) and MAY have an additional filtering array. If filtering is present, request with attributes in the array will be delegated, others will be treated normally (i.e. by Prosody).

If you are not a developer, the delegated namespace(s)/attribute(s) are most probably specified with the external component/entity you want to use.

The pseudo-namespace http://jabber.org/protocol/disco#items:* is used to delegate remaining disco#items (i.e. items nodes not already handled by Prosody itself).

Compatibility

If you use it with Prosody 0.9 and a component, you need to patch core/mod_component.lua to fire a new signal. To do it, copy the following patch in a, for example, /tmp/component.patch file:

diff --git a/plugins/mod_component.lua b/plugins/mod_component.lua
--- a/plugins/mod_component.lua
+++ b/plugins/mod_component.lua
@@ -85,6 +85,7 @@
                session.type = "component";
                module:log("info", "External component successfully authenticated");
                session.send(st.stanza("handshake"));
+               module:fire_event("component-authenticated", { session = session });

                return true;
        end

Then, at the root of prosody, enter:

patch -p1 < /tmp/component.patch

Note

This module is often used with mod_privilege (c.f. XEP for more details)

sudo prosodyctl install --server=https://modules.prosody.im/rocks/ mod_delegation