--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mod_sasl2_bind2/README.md	Fri Sep 02 16:22:11 2022 +0100
@@ -0,0 +1,7 @@
+---
+labels:
+- Stage-Alpha
+summary: "Bind 2 integration with SASL2"
+---
+
+Add support for inlining Bind 2.0 into the SASL2 process. Experimental WIP.

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mod_sasl2_bind2/mod_sasl2_bind2.lua	Fri Sep 02 16:22:11 2022 +0100
@@ -0,0 +1,112 @@
+local base64 = require "util.encodings".base64;
+local sha1 = require "util.hashes".sha1;
+local st = require "util.stanza";
+
+local sm_bind_resource = require "core.sessionmanager".bind_resource;
+
+local xmlns_bind2 = "urn:xmpp:bind2:1";
+local xmlns_sasl2 = "urn:xmpp:sasl2:1";
+
+-- Advertise what we can do
+
+module:hook("stream-features", function(event)
+	local origin, features = event.origin, event.features;
+
+	if origin.type ~= "c2s_unauthed" then
+		return;
+	end
+
+	local inline = st.stanza("inline", { xmlns = xmlns_bind2 });
+	module:fire_event("advertise-bind-features", { origin = origin, features = inline });
+	features:add_direct_child(inline);
+end, 1);
+
+module:hook("advertise-sasl-features", function(event)
+	event.features:tag("bind", { xmlns = xmlns_bind2 }):up();
+end, 1);
+
+-- Helper to actually bind a resource to a session
+
+local function do_bind(session, bind_request)
+	local resource;
+
+	local client_id_tag = bind_request:get_child("client-id");
+	local client_id = client_id_tag and client_id_tag:text() or session.client_id;
+	if client_id and client_id ~= "" then
+		local tag = client_id_tag and client_id_tag.attr.tag or "client";
+		resource = ("%s~%s"):format(tag, base64.encode(sha1(client_id):sub(1, 9)));
+	end
+
+	local success, err_type, err, err_msg = sm_bind_resource(session, resource);
+	if not success then
+		session.log("debug", "Resource bind failed: %s", err_msg or err);
+		return nil, { type = err_type, condition = err, text = err_msg };
+	end
+
+	session.log("debug", "Resource bound: %s", session.full_jid);
+	return st.stanza("bound", { xmlns = xmlns_bind2 })
+		:text_tag("jid", session.full_jid)
+end
+
+-- Enable inline features requested by the client
+
+local function enable_features(session, bind_request, bind_result)
+	local features = bind_request:get_child("features");
+	if not features then return; end
+	module:fire_event("process-bind-features", {
+		session = session;
+		features = features;
+		result = bind_result;
+	});
+end
+
+-- SASL 2 integration
+
+module:hook_tag(xmlns_sasl2, "authenticate", function (session, auth)
+	-- Cache action for future processing (after auth success)
+	session.sasl2_bind_request = auth:child_with_ns(xmlns_bind2);
+end, 100);
+
+module:hook("sasl2/c2s/success", function (event)
+	local session = event.session;
+
+	local bind_request = session.sasl2_bind_request;
+	if not bind_request then return; end -- No bind requested
+	session.sasl2_bind_request = nil;
+
+	local sm_success = event.sasl2_sm_success;
+	if sm_success and sm_success.type == "resumed" then
+		return; -- No need to bind a resource
+	end
+
+	local bind_result, err = do_bind(session, bind_request);
+	if not bind_result then
+		bind_result = st.stanza("failed", { xmlns = xmlns_bind2 })
+			:add_error(err);
+	else
+		enable_features(session, bind_request, bind_result);
+	end
+
+	event.success:add_child(bind_result);
+end, 100);
+
+-- Inline features
+
+module:hook("advertise-bind-features", function (event)
+	local features = event.features;
+	features:tag("feature", { var = "urn:xmpp:carbons:2" }):up();
+	features:tag("feature", { var = "urn:xmpp:csi:0" }):up();
+end);
+
+module:hook("enable-bind-features", function (event)
+	local session, features = event.session, event.features;
+
+	-- Carbons
+	session.want_carbons = not not features:get_child("enable", "urn:xmpp:carbons:2");
+
+	-- CSI
+	local csi_state_tag = features:child_with_ns("urn:xmpp:csi:0");
+	if csi_state_tag then
+		session.state = csi_state_tag.name;
+	end
+end, 10);