prosody/plugins/mod_dialback.lua

local format = string.format;
local send_s2s = require "core.s2smanager".send_to_host;
local s2s_make_authenticated = require "core.s2smanager".make_authenticated;
local s2s_verify_dialback = require "core.s2smanager".verify_dialback;

local log = require "util.logger".init("mod_dialback");

local xmlns_dialback = "jabber:server:dialback";

add_handler({"s2sin_unauthed", "s2sin"}, "verify", xmlns_dialback,
		function (origin, stanza)
			-- We are being asked to verify the key, to ensure it was generated by us
			log("debug", "verifying dialback key...");
			local attr = stanza.attr;
			-- FIXME: Grr, ejabberd breaks this one too?? it is black and white in XEP-220 example 34
			--if attr.from ~= origin.to_host then error("invalid-from"); end
			local type;
			if s2s_verify_dialback(attr.id, attr.from, attr.to, stanza[1]) then
				type = "valid"
			else
				type = "invalid"
				log("warn", "Asked to verify a dialback key that was incorrect. An imposter is claiming to be %s?", attr.to);
			end
			origin.sends2s(format("<db:verify from='%s' to='%s' id='%s' type='%s'>%s</db:verify>", attr.to, attr.from, attr.id, type, stanza[1]));		
		end);

add_handler("s2sin_unauthed", "result", xmlns_dialback,
		function (origin, stanza)
			-- he wants to be identified through dialback
			-- We need to check the key with the Authoritative server
			local attr = stanza.attr;
			local attr = stanza.attr;
			origin.from_host = attr.from;
			origin.to_host = attr.to;
			origin.dialback_key = stanza[1];
			log("debug", "asking %s if key %s belongs to them", origin.from_host, origin.dialback_key);
			send_s2s(origin.to_host, origin.from_host, format("<db:verify from='%s' to='%s' id='%s'>%s</db:verify>", origin.to_host, origin.from_host, origin.streamid, origin.dialback_key));
			hosts[origin.from_host].dialback_verifying = origin;
		end);

add_handler({ "s2sout_unauthed", "s2sout" }, "verify", xmlns_dialback,
		function (origin, stanza)
			if origin.dialback_verifying then
				local valid;
				local attr = stanza.attr;
				if attr.type == "valid" then
					s2s_make_authenticated(origin.dialback_verifying);
					valid = "valid";
				else
					-- Warn the original connection that is was not verified successfully
					log("warn", "dialback for "..(origin.dialback_verifying.from_host or "(unknown)").." failed");
					valid = "invalid";
				end
				origin.dialback_verifying.sends2s(format("<db:result from='%s' to='%s' id='%s' type='%s'>%s</db:result>", attr.from, attr.to, attr.id, valid, origin.dialback_verifying.dialback_key));
			end
		end);

add_handler({ "s2sout_unauthed", "s2sout" }, "result", xmlns_dialback,
		function (origin, stanza)
			if stanza.attr.type == "valid" then
				s2s_make_authenticated(origin);
			else
				-- FIXME
				error("dialback failed!");
			end
		end);