--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mod_debug_omemo/mod_debug_omemo.lua	Mon Sep 13 19:24:13 2021 +0100
@@ -0,0 +1,223 @@
+local array = require "util.array";
+local jid = require "util.jid";
+local set = require "util.set";
+local st = require "util.stanza";
+local url_escape = require "util.http".urlencode;
+
+local base_url = "https://"..module.host.."/";
+
+local render_html_template = require"util.interpolation".new("%b{}", st.xml_escape, {
+	urlescape = url_escape;
+	lower = string.lower;
+	classname = function (s) return (s:gsub("%W+", "-")); end;
+	relurl = function (s)
+		if s:match("^%w+://") then
+			return s;
+		end
+		return base_url.."/"..s;
+	end;
+});
+local render_url = require "util.interpolation".new("%b{}", url_escape, {
+	urlescape = url_escape;
+	noscheme = function (url)
+		return (url:gsub("^[^:]+:", ""));
+	end;
+});
+
+local mod_pep = module:depends("pep");
+
+local mam = module:open_store("archive", "archive");
+
+local function get_user_omemo_info(username)
+	local everything_valid = true;
+	local any_device = false;
+	local omemo_status = {};
+	local omemo_devices;
+	local pep_service = mod_pep.get_pep_service(username);
+	if pep_service and pep_service.nodes then
+		local ok, _, device_list = pep_service:get_last_item("eu.siacs.conversations.axolotl.devicelist", true);
+		if ok and device_list then
+			device_list = device_list:get_child("list", "eu.siacs.conversations.axolotl");
+		end
+		if device_list then
+			omemo_devices = {};
+			for device_entry in device_list:childtags("device") do
+				any_device = true;
+				local device_info = {};
+				local device_id = tonumber(device_entry.attr.id or "");
+				if device_id then
+					device_info.id = device_id;
+					local bundle_id = ("eu.siacs.conversations.axolotl.bundles:%d"):format(device_id);
+					local have_bundle, _, bundle = pep_service:get_last_item(bundle_id, true);
+					if have_bundle and bundle and bundle:get_child("bundle", "eu.siacs.conversations.axolotl") then
+						device_info.have_bundle = true;
+						local config_ok, bundle_config = pep_service:get_node_config(bundle_id, true);
+						if config_ok and bundle_config then
+							device_info.bundle_config = bundle_config;
+							if bundle_config.max_items == 1
+							and bundle_config.access_model == "open"
+							and bundle_config.persist_items == true
+							and bundle_config.publish_model == "publishers" then
+								device_info.valid = true;
+							end
+						end
+					end
+				end
+				if device_info.valid == nil then
+					device_info.valid = false;
+					everything_valid = false;
+				end
+				table.insert(omemo_devices, device_info);
+			end
+
+			local config_ok, list_config = pep_service:get_node_config("eu.siacs.conversations.axolotl.devicelist", true);
+			if config_ok and list_config then
+				omemo_status.config = list_config;
+				if list_config.max_items == 1
+				and list_config.access_model == "open"
+				and list_config.persist_items == true
+				and list_config.publish_model == "publishers" then
+					omemo_status.config_valid = true;
+				end
+			end
+			if omemo_status.config_valid == nil then
+				omemo_status.config_valid = false;
+				everything_valid = false;
+			end
+		end
+	end
+	omemo_status.valid = everything_valid and any_device;
+	return {
+		status = omemo_status;
+		devices = omemo_devices;
+	};
+end
+
+local access_model_text = {
+	open = "Public";
+	whitelist = "Private";
+	roster = "Contacts only";
+	presence = "Contacts only";
+};
+
+local function render_message(event, path)
+	local username, message_id = path:match("^([^/]+)/(.+)$");
+	if not username then
+		return 400;
+	end
+	local message;
+	for _, result in mam:find(username, { key = message_id }) do
+		message = result;
+	end
+	if not message then
+		return 404;
+	end
+
+	local user_omemo_status = get_user_omemo_info(username);
+
+	local user_rids = set.new(array.pluck(user_omemo_status.devices or {}, "id")) / tostring;
+
+	local message_omemo_header = message:find("{eu.siacs.conversations.axolotl}encrypted/header");
+	local message_rids = set.new();
+	local rid_info = {};
+	if message_omemo_header then
+		for key_el in message_omemo_header:childtags("key") do
+			local rid = key_el.attr.rid;
+			if rid then
+				message_rids:add(rid);
+				local prekey = key_el.attr.prekey;
+				rid_info = {
+					prekey = prekey and (prekey == "1" or prekey:lower() == "true");
+				};
+			end
+		end
+	end
+
+	local rids = user_rids + message_rids;
+
+	local direction = jid.bare(message.attr.to) == (username.."@"..module.host) and "incoming" or "outgoing";
+
+	local is_encrypted = not not message_omemo_header;
+
+	local sender_id = message_omemo_header and message_omemo_header.attr.sid or nil;
+
+	local f = module:load_resource("view.tpl.html");
+	if not f then
+		return 500;
+	end
+	local tpl = f:read("*a");
+
+	local data = { user = username, rids = {} };
+	for rid in rids do
+		data.rids[rid] = {
+			status = message_rids:contains(rid) and "Encrypted" or user_rids:contains(rid) and "Missing" or nil;
+			prekey = rid_info.prekey;
+		};
+	end
+
+	data.message = {
+		type = message.attr.type or "normal";
+		direction = direction;
+		encryption = is_encrypted and "encrypted" or "unencrypted";
+	};
+
+	data.omemo = {
+		sender_id = sender_id;
+		status = user_omemo_status.status.valid and "no known issues" or "problems";
+	};
+
+	data.omemo.devices = {};
+	for _, device_info in ipairs(user_omemo_status.devices) do
+		data.omemo.devices[("%d"):format(device_info.id)] = {
+			status = device_info.valid and "OK" or "Problem";
+			bundle = device_info.have_bundle and "Published" or "Missing";
+			access_model = access_model_text[device_info.bundle_config and device_info.bundle_config.access_model or nil];
+		};
+	end
+
+	event.response.headers.content_type = "text/html; charset=utf-8";
+	return render_html_template(tpl, data);
+end
+
+local function check_omemo_fallback(event)
+	local message = event.stanza;
+
+	local message_omemo_header = message:find("{eu.siacs.conversations.axolotl}encrypted/header");
+	if not message_omemo_header then return; end
+
+	local to_bare = jid.bare(message.attr.to);
+
+	local archive_stanza_id;
+	for stanza_id_tag in message:childtags("stanza-id", "urn:xmpp:sid:0") do
+		if stanza_id_tag.attr.by == to_bare then
+			archive_stanza_id = stanza_id_tag.attr.id;
+		end
+	end
+	if not archive_stanza_id then
+		return;
+	end
+
+	local debug_url = render_url(module:http_url().."/view/{username}/{message_id}", {
+		username = jid.node(to_bare);
+		message_id = archive_stanza_id;
+	});
+
+	local body = message:get_child("body");
+	if not body then
+		body = st.stanza("body")
+			:text("This message is encrypted using OMEMO, but could not be decrypted by your device.\nFor more information see: "..debug_url);
+		message:reset():add_child(body);
+	else
+		body:text("\n\nOMEMO debug information: "..debug_url);
+	end
+end
+
+module:hook("message/bare", check_omemo_fallback, 1);
+module:hook("message/full", check_omemo_fallback, 1);
+
+module:depends("http")
+module:provides("http", {
+	route = {
+		["GET /view/*"] = render_message;
+	};
+});