mod_carbons: Import XEP-0280 implementation from prosody-modules (sans compat with...

diff --git a/plugins/mod_carbons.lua b/plugins/mod_carbons.lua
new file mode 100644 (file)
index 0000000..5124280
--- /dev/null
+++ b/plugins/mod_carbons.lua
@@ -0,0 +1,111 @@
+-- XEP-0280: Message Carbons implementation for Prosody
+-- Copyright (C) 2011 Kim Alvefur
+--
+-- This file is MIT/X11 licensed.
+
+local st = require "util.stanza";
+local jid_bare = require "util.jid".bare;
+local xmlns_carbons = "urn:xmpp:carbons:2";
+local xmlns_forward = "urn:xmpp:forward:0";
+local full_sessions, bare_sessions = full_sessions, bare_sessions;
+
+local function toggle_carbons(event)
+       local origin, stanza = event.origin, event.stanza;
+       local state = stanza.tags[1].name;
+       module:log("debug", "%s %sd carbons", origin.full_jid, state);
+       origin.want_carbons = state == "enable" and stanza.tags[1].attr.xmlns;
+       return origin.send(st.reply(stanza));
+end
+module:hook("iq-set/self/"..xmlns_carbons..":disable", toggle_carbons);
+module:hook("iq-set/self/"..xmlns_carbons..":enable", toggle_carbons);
+
+local function message_handler(event, c2s)
+       local origin, stanza = event.origin, event.stanza;
+       local orig_type = stanza.attr.type;
+       local orig_from = stanza.attr.from;
+       local orig_to = stanza.attr.to;
+       
+       if not (orig_type == nil
+                       or orig_type == "normal"
+                       or orig_type == "chat") then
+               return -- No carbons for messages of type error or headline
+       end
+
+       -- Stanza sent by a local client
+       local bare_jid = jid_bare(orig_from);
+       local target_session = origin;
+       local top_priority = false;
+       local user_sessions = bare_sessions[bare_jid];
+
+       -- Stanza about to be delivered to a local client
+       if not c2s then
+               bare_jid = jid_bare(orig_to);
+               target_session = full_sessions[orig_to];
+               user_sessions = bare_sessions[bare_jid];
+               if not target_session and user_sessions then
+                       -- The top resources will already receive this message per normal routing rules,
+                       -- so we are going to skip them in order to avoid sending duplicated messages.
+                       local top_resources = user_sessions.top_resources;
+                       top_priority = top_resources and top_resources[1].priority
+               end
+       end
+
+       if not user_sessions then
+               module:log("debug", "Skip carbons for offline user");
+               return -- No use in sending carbons to an offline user
+       end
+
+       if stanza:get_child("private", xmlns_carbons) then
+               if not c2s then
+                       stanza:maptags(function(tag)
+                               if not ( tag.attr.xmlns == xmlns_carbons and tag.name == "private" ) then
+                                       return tag;
+                               end
+                       end);
+               end
+               module:log("debug", "Message tagged private, ignoring");
+               return
+       elseif stanza:get_child("no-copy", "urn:xmpp:hints") then
+               module:log("debug", "Message has no-copy hint, ignoring");
+               return
+       elseif stanza:get_child("x", "http://jabber.org/protocol/muc#user") then
+               module:log("debug", "MUC PM, ignoring");
+               return
+       end
+
+       -- Create the carbon copy and wrap it as per the Stanza Forwarding XEP
+       local copy = st.clone(stanza);
+       copy.attr.xmlns = "jabber:client";
+       local carbon = st.message{ from = bare_jid, type = orig_type, }
+               :tag(c2s and "sent" or "received", { xmlns = xmlns_carbons })
+                       :tag("forwarded", { xmlns = xmlns_forward })
+                               :add_child(copy):reset();
+
+       user_sessions = user_sessions and user_sessions.sessions;
+       for _, session in pairs(user_sessions) do
+               -- Carbons are sent to resources that have enabled it
+               if session.want_carbons
+               -- but not the resource that sent the message, or the one that it's directed to
+               and session ~= target_session
+               -- and isn't among the top resources that would receive the message per standard routing rules
+               and (c2s or session.priority ~= top_priority) then
+                       carbon.attr.to = session.full_jid;
+                       module:log("debug", "Sending carbon to %s", session.full_jid);
+                       session.send(carbon);
+               end
+       end
+end
+
+local function c2s_message_handler(event)
+       return message_handler(event, true)
+end
+
+-- Stanzas sent by local clients
+module:hook("pre-message/host", c2s_message_handler, 1);
+module:hook("pre-message/bare", c2s_message_handler, 1);
+module:hook("pre-message/full", c2s_message_handler, 1);
+-- Stanzas to local clients
+module:hook("message/bare", message_handler, 1);
+module:hook("message/full", message_handler, 1);
+
+module:add_feature(xmlns_carbons);