mod_s2s_auth_certs: Split PKIX based certificate checking from mod_s2s into new plugin

[prosody.git] / plugins / mod_s2s / mod_s2s.lua

-- Prosody IM
-- Copyright (C) 2008-2010 Matthew Wild
-- Copyright (C) 2008-2010 Waqas Hussain
--
-- This project is MIT/X11 licensed. Please see the
-- COPYING file in the source package for more information.
--

module:set_global();

local prosody = prosody;
local hosts = prosody.hosts;
local core_process_stanza = prosody.core_process_stanza;

local tostring, type = tostring, type;
local t_insert = table.insert;
local xpcall, traceback = xpcall, debug.traceback;
local NULL = {};

local add_task = require "util.timer".add_task;
local st = require "util.stanza";
local initialize_filters = require "util.filters".initialize;
local nameprep = require "util.encodings".stringprep.nameprep;
local new_xmpp_stream = require "util.xmppstream".new;
local s2s_new_incoming = require "core.s2smanager".new_incoming;
local s2s_new_outgoing = require "core.s2smanager".new_outgoing;
local s2s_destroy_session = require "core.s2smanager".destroy_session;
local uuid_gen = require "util.uuid".generate;
local cert_verify_identity = require "util.x509".verify_identity;
local fire_global_event = prosody.events.fire_event;

local s2sout = module:require("s2sout");

local connect_timeout = module:get_option_number("s2s_timeout", 90);
local stream_close_timeout = module:get_option_number("s2s_close_timeout", 5);
local opt_keepalives = module:get_option_boolean("s2s_tcp_keepalives", module:get_option_boolean("tcp_keepalives", true));
local secure_auth = module:get_option_boolean("s2s_secure_auth", false); -- One day...
local secure_domains, insecure_domains =
        module:get_option_set("s2s_secure_domains", {})._items, module:get_option_set("s2s_insecure_domains", {})._items;
local require_encryption = module:get_option_boolean("s2s_require_encryption", false);

local sessions = module:shared("sessions");

local log = module._log;

--- Handle stanzas to remote domains

local bouncy_stanzas = { message = true, presence = true, iq = true };
local function bounce_sendq(session, reason)
        local sendq = session.sendq;
        if not sendq then return; end
        session.log("info", "sending error replies for "..#sendq.." queued stanzas because of failed outgoing connection to "..tostring(session.to_host));
        local dummy = {
                type = "s2sin";
                send = function(s)
                        (session.log or log)("error", "Replying to to an s2s error reply, please report this! Traceback: %s", traceback());
                end;
                dummy = true;
        };
        for i, data in ipairs(sendq) do
                local reply = data[2];
                if reply and not(reply.attr.xmlns) and bouncy_stanzas[reply.name] then
                        reply.attr.type = "error";
                        reply:tag("error", {type = "cancel"})
                                :tag("remote-server-not-found", {xmlns = "urn:ietf:params:xml:ns:xmpp-stanzas"}):up();
                        if reason then
                                reply:tag("text", {xmlns = "urn:ietf:params:xml:ns:xmpp-stanzas"})
                                        :text("Server-to-server connection failed: "..reason):up();
                        end
                        core_process_stanza(dummy, reply);
                end
                sendq[i] = nil;
        end
        session.sendq = nil;
end

-- Handles stanzas to existing s2s sessions
function route_to_existing_session(event)
        local from_host, to_host, stanza = event.from_host, event.to_host, event.stanza;
        if not hosts[from_host] then
                log("warn", "Attempt to send stanza from %s - a host we don't serve", from_host);
                return false;
        end
        if hosts[to_host] then
                log("warn", "Attempt to route stanza to a remote %s - a host we do serve?!", from_host);
                return false;
        end
        local host = hosts[from_host].s2sout[to_host];
        if host then
                -- We have a connection to this host already
                if host.type == "s2sout_unauthed" and (stanza.name ~= "db:verify" or not host.dialback_key) then
                        (host.log or log)("debug", "trying to send over unauthed s2sout to "..to_host);

                        -- Queue stanza until we are able to send it
                        if host.sendq then t_insert(host.sendq, {tostring(stanza), stanza.attr.type ~= "error" and stanza.attr.type ~= "result" and st.reply(stanza)});
                        else host.sendq = { {tostring(stanza), stanza.attr.type ~= "error" and stanza.attr.type ~= "result" and st.reply(stanza)} }; end
                        host.log("debug", "stanza [%s] queued ", stanza.name);
                        return true;
                elseif host.type == "local" or host.type == "component" then
                        log("error", "Trying to send a stanza to ourselves??")
                        log("error", "Traceback: %s", traceback());
                        log("error", "Stanza: %s", tostring(stanza));
                        return false;
                else
                        (host.log or log)("debug", "going to send stanza to "..to_host.." from "..from_host);
                        -- FIXME
                        if host.from_host ~= from_host then
                                log("error", "WARNING! This might, possibly, be a bug, but it might not...");
                                log("error", "We are going to send from %s instead of %s", tostring(host.from_host), tostring(from_host));
                        end
                        if host.sends2s(stanza) then
                                host.log("debug", "stanza sent over %s", host.type);
                                return true;
                        end
                end
        end
end

-- Create a new outgoing session for a stanza
function route_to_new_session(event)
        local from_host, to_host, stanza = event.from_host, event.to_host, event.stanza;
        log("debug", "opening a new outgoing connection for this stanza");
        local host_session = s2s_new_outgoing(from_host, to_host);

        -- Store in buffer
        host_session.bounce_sendq = bounce_sendq;
        host_session.sendq = { {tostring(stanza), stanza.attr.type ~= "error" and stanza.attr.type ~= "result" and st.reply(stanza)} };
        log("debug", "stanza [%s] queued until connection complete", tostring(stanza.name));
        s2sout.initiate_connection(host_session);
        if (not host_session.connecting) and (not host_session.conn) then
                log("warn", "Connection to %s failed already, destroying session...", to_host);
                s2s_destroy_session(host_session, "Connection failed");
                return false;
        end
        return true;
end

local function keepalive(event)
        return event.session.sends2s(' ');
end

module:hook("s2s-read-timeout", keepalive, -1);

function module.add_host(module)
        if module:get_option_boolean("disallow_s2s", false) then
                module:log("warn", "The 'disallow_s2s' config option is deprecated, please see http://prosody.im/doc/s2s#disabling");
                return nil, "This host has disallow_s2s set";
        end
        module:hook("route/remote", route_to_existing_session, -1);
        module:hook("route/remote", route_to_new_session, -10);
        module:hook("s2s-authenticated", make_authenticated, -1);
        module:hook("s2s-read-timeout", keepalive, -1);
        module:hook_stanza("http://etherx.jabber.org/streams", "features", function (session, stanza)
                if session.type == "s2sout" then
                        -- Stream is authenticated and we are seem to be done with feature negotiation,
                        -- so the stream is ready for stanzas.  RFC 6120 Section 4.3
                        mark_connected(session);
                end
        end, -1);
end

-- Stream is authorised, and ready for normal stanzas
function mark_connected(session)
        local sendq, send = session.sendq, session.sends2s;

        local from, to = session.from_host, session.to_host;

        session.log("info", "%s s2s connection %s->%s complete", session.direction:gsub("^.", string.upper), from, to);

        local event_data = { session = session };
        if session.type == "s2sout" then
                fire_global_event("s2sout-established", event_data);
                hosts[from].events.fire_event("s2sout-established", event_data);
        else
                local host_session = hosts[to];
                session.send = function(stanza)
                        return host_session.events.fire_event("route/remote", { from_host = to, to_host = from, stanza = stanza });
                end;

                fire_global_event("s2sin-established", event_data);
                hosts[to].events.fire_event("s2sin-established", event_data);
        end

        if session.direction == "outgoing" then
                if sendq then
                        session.log("debug", "sending %d queued stanzas across new outgoing connection to %s", #sendq, session.to_host);
                        for i, data in ipairs(sendq) do
                                send(data[1]);
                                sendq[i] = nil;
                        end
                        session.sendq = nil;
                end

                session.ip_hosts = nil;
                session.srv_hosts = nil;
        end
end

function make_authenticated(event)
        local session, host = event.session, event.host;
        if not session.secure then
                if require_encryption or (secure_auth and not(insecure_domains[host])) or secure_domains[host] then
                        session:close({
                                condition = "policy-violation",
                                text = "Encrypted server-to-server communication is required but was not "
                                       ..((session.direction == "outgoing" and "offered") or "used")
                        });
                end
        end
        if hosts[host] then
                session:close({ condition = "undefined-condition", text = "Attempt to authenticate as a host we serve" });
        end
        if session.type == "s2sout_unauthed" then
                session.type = "s2sout";
        elseif session.type == "s2sin_unauthed" then
                session.type = "s2sin";
                if host then
                        if not session.hosts[host] then session.hosts[host] = {}; end
                        session.hosts[host].authed = true;
                end
        elseif session.type == "s2sin" and host then
                if not session.hosts[host] then session.hosts[host] = {}; end
                session.hosts[host].authed = true;
        else
                return false;
        end
        session.log("debug", "connection %s->%s is now authenticated for %s", session.from_host, session.to_host, host);

        if (session.type == "s2sout" and session.external_auth ~= "succeeded") or session.type == "s2sin" then
                -- Stream either used dialback for authentication or is an incoming stream.
                mark_connected(session);
        end

        return true;
end

--- Helper to check that a session peer's certificate is valid
function check_cert_status(session)
        local host = session.direction == "outgoing" and session.to_host or session.from_host
        local conn = session.conn:socket()
        local cert
        if conn.getpeercertificate then
                cert = conn:getpeercertificate()
        end

        return module:fire_event("s2s-check-certificate", { host = host, session = session, cert = cert });
end

--- XMPP stream event handlers

local stream_callbacks = { default_ns = "jabber:server", handlestanza =  core_process_stanza };

local xmlns_xmpp_streams = "urn:ietf:params:xml:ns:xmpp-streams";

function stream_callbacks.streamopened(session, attr)
        local send = session.sends2s;

        session.version = tonumber(attr.version) or 0;

        -- TODO: Rename session.secure to session.encrypted
        if session.secure == false then
                session.secure = true;
                session.encrypted = true;

                local sock = session.conn:socket();
                if sock.info then
                        local info = sock:info();
                        (session.log or log)("info", "Stream encrypted (%s with %s)", info.protocol, info.cipher);
                        session.compressed = info.compression;
                else
                        (session.log or log)("info", "Stream encrypted");
                        session.compressed = sock.compression and sock:compression(); --COMPAT mw/luasec-hg
                end
        end

        if session.direction == "incoming" then
                -- Send a reply stream header

                -- Validate to/from
                local to, from = nameprep(attr.to), nameprep(attr.from);
                if not to and attr.to then -- COMPAT: Some servers do not reliably set 'to' (especially on stream restarts)
                        session:close({ condition = "improper-addressing", text = "Invalid 'to' address" });
                        return;
                end
                if not from and attr.from then -- COMPAT: Some servers do not reliably set 'from' (especially on stream restarts)
                        session:close({ condition = "improper-addressing", text = "Invalid 'from' address" });
                        return;
                end

                -- Set session.[from/to]_host if they have not been set already and if
                -- this session isn't already authenticated
                if session.type == "s2sin_unauthed" and from and not session.from_host then
                        session.from_host = from;
                elseif from ~= session.from_host then
                        session:close({ condition = "improper-addressing", text = "New stream 'from' attribute does not match original" });
                        return;
                end
                if session.type == "s2sin_unauthed" and to and not session.to_host then
                        session.to_host = to;
                elseif to ~= session.to_host then
                        session:close({ condition = "improper-addressing", text = "New stream 'to' attribute does not match original" });
                        return;
                end

                -- For convenience we'll put the sanitised values into these variables
                to, from = session.to_host, session.from_host;

                session.streamid = uuid_gen();
                (session.log or log)("debug", "Incoming s2s received %s", st.stanza("stream:stream", attr):top_tag());
                if to then
                        if not hosts[to] then
                                -- Attempting to connect to a host we don't serve
                                session:close({
                                        condition = "host-unknown";
                                        text = "This host does not serve "..to
                                });
                                return;
                        elseif not hosts[to].modules.s2s then
                                -- Attempting to connect to a host that disallows s2s
                                session:close({
                                        condition = "policy-violation";
                                        text = "Server-to-server communication is disabled for this host";
                                });
                                return;
                        end
                end

                if hosts[from] then
                        session:close({ condition = "undefined-condition", text = "Attempt to connect from a host we serve" });
                        return;
                end

                if session.secure and not session.cert_chain_status then
                        if check_cert_status(session) == false then
                                return;
                        end
                end

                session:open_stream(session.to_host, session.from_host)
                if session.version >= 1.0 then
                        local features = st.stanza("stream:features");

                        if to then
                                hosts[to].events.fire_event("s2s-stream-features", { origin = session, features = features });
                        else
                                (session.log or log)("warn", "No 'to' on stream header from %s means we can't offer any features", from or session.ip or "unknown host");
                        end

                        log("debug", "Sending stream features: %s", tostring(features));
                        send(features);
                end
        elseif session.direction == "outgoing" then
                -- If we are just using the connection for verifying dialback keys, we won't try and auth it
                if not attr.id then error("stream response did not give us a streamid!!!"); end
                session.streamid = attr.id;

                if session.secure and not session.cert_chain_status then
                        if check_cert_status(session) == false then
                                return;
                        end
                end

                -- Send unauthed buffer
                -- (stanzas which are fine to send before dialback)
                -- Note that this is *not* the stanza queue (which
                -- we can only send if auth succeeds) :)
                local send_buffer = session.send_buffer;
                if send_buffer and #send_buffer > 0 then
                        log("debug", "Sending s2s send_buffer now...");
                        for i, data in ipairs(send_buffer) do
                                session.sends2s(tostring(data));
                                send_buffer[i] = nil;
                        end
                end
                session.send_buffer = nil;

                -- If server is pre-1.0, don't wait for features, just do dialback
                if session.version < 1.0 then
                        if not session.dialback_verifying then
                                hosts[session.from_host].events.fire_event("s2sout-authenticate-legacy", { origin = session });
                        else
                                mark_connected(session);
                        end
                end
        end
        session.notopen = nil;
end

function stream_callbacks.streamclosed(session)
        (session.log or log)("debug", "Received </stream:stream>");
        session:close(false);
end

function stream_callbacks.error(session, error, data)
        if error == "no-stream" then
                session:close("invalid-namespace");
        elseif error == "parse-error" then
                session.log("debug", "Server-to-server XML parse error: %s", tostring(error));
                session:close("not-well-formed");
        elseif error == "stream-error" then
                local condition, text = "undefined-condition";
                for child in data:children() do
                        if child.attr.xmlns == xmlns_xmpp_streams then
                                if child.name ~= "text" then
                                        condition = child.name;
                                else
                                        text = child:get_text();
                                end
                                if condition ~= "undefined-condition" and text then
                                        break;
                                end
                        end
                end
                text = condition .. (text and (" ("..text..")") or "");
                session.log("info", "Session closed by remote with error: %s", text);
                session:close(nil, text);
        end
end

local function handleerr(err) log("error", "Traceback[s2s]: %s", traceback(tostring(err), 2)); end
function stream_callbacks.handlestanza(session, stanza)
        if stanza.attr.xmlns == "jabber:client" then --COMPAT: Prosody pre-0.6.2 may send jabber:client
                stanza.attr.xmlns = nil;
        end
        stanza = session.filter("stanzas/in", stanza);
        if stanza then
                return xpcall(function () return core_process_stanza(session, stanza) end, handleerr);
        end
end

local listener = {};

--- Session methods
local stream_xmlns_attr = {xmlns='urn:ietf:params:xml:ns:xmpp-streams'};
local function session_close(session, reason, remote_reason)
        local log = session.log or log;
        if session.conn then
                if session.notopen then
                        if session.direction == "incoming" then
                                session:open_stream(session.to_host, session.from_host);
                        else
                                session:open_stream(session.from_host, session.to_host);
                        end
                end
                if reason then -- nil == no err, initiated by us, false == initiated by remote
                        if type(reason) == "string" then -- assume stream error
                                log("debug", "Disconnecting %s[%s], <stream:error> is: %s", session.host or session.ip or "(unknown host)", session.type, reason);
                                session.sends2s(st.stanza("stream:error"):tag(reason, {xmlns = 'urn:ietf:params:xml:ns:xmpp-streams' }));
                        elseif type(reason) == "table" then
                                if reason.condition then
                                        local stanza = st.stanza("stream:error"):tag(reason.condition, stream_xmlns_attr):up();
                                        if reason.text then
                                                stanza:tag("text", stream_xmlns_attr):text(reason.text):up();
                                        end
                                        if reason.extra then
                                                stanza:add_child(reason.extra);
                                        end
                                        log("debug", "Disconnecting %s[%s], <stream:error> is: %s", session.host or session.ip or "(unknown host)", session.type, tostring(stanza));
                                        session.sends2s(stanza);
                                elseif reason.name then -- a stanza
                                        log("debug", "Disconnecting %s->%s[%s], <stream:error> is: %s", session.from_host or "(unknown host)", session.to_host or "(unknown host)", session.type, tostring(reason));
                                        session.sends2s(reason);
                                end
                        end
                end

                session.sends2s("</stream:stream>");
                function session.sends2s() return false; end

                local reason = remote_reason or (reason and (reason.text or reason.condition)) or reason;
                session.log("info", "%s s2s stream %s->%s closed: %s", session.direction:gsub("^.", string.upper), session.from_host or "(unknown host)", session.to_host or "(unknown host)", reason or "stream closed");

                -- Authenticated incoming stream may still be sending us stanzas, so wait for </stream:stream> from remote
                local conn = session.conn;
                if reason == nil and not session.notopen and session.type == "s2sin" then
                        add_task(stream_close_timeout, function ()
                                if not session.destroyed then
                                        session.log("warn", "Failed to receive a stream close response, closing connection anyway...");
                                        s2s_destroy_session(session, reason);
                                        conn:close();
                                end
                        end);
                else
                        s2s_destroy_session(session, reason);
                        conn:close(); -- Close immediately, as this is an outgoing connection or is not authed
                end
        end
end

function session_stream_attrs(session, from, to, attr)
        if not from or (hosts[from] and hosts[from].modules.dialback) then
                attr["xmlns:db"] = 'jabber:server:dialback';
        end
end

-- Session initialization logic shared by incoming and outgoing
local function initialize_session(session)
        local stream = new_xmpp_stream(session, stream_callbacks);
        local log = session.log or log;
        session.stream = stream;

        session.notopen = true;

        function session.reset_stream()
                session.notopen = true;
                session.stream:reset();
        end

        session.stream_attrs = session_stream_attrs;

        local filter = initialize_filters(session);
        local conn = session.conn;
        local w = conn.write;

        function session.sends2s(t)
                log("debug", "sending: %s", t.top_tag and t:top_tag() or t:match("^[^>]*>?"));
                if t.name then
                        t = filter("stanzas/out", t);
                end
                if t then
                        t = filter("bytes/out", tostring(t));
                        if t then
                                return w(conn, t);
                        end
                end
        end

        function session.data(data)
                data = filter("bytes/in", data);
                if data then
                        local ok, err = stream:feed(data);
                        if ok then return; end
                        log("warn", "Received invalid XML: %s", data);
                        log("warn", "Problem was: %s", err);
                        session:close("not-well-formed");
                end
        end

        session.close = session_close;

        local handlestanza = stream_callbacks.handlestanza;
        function session.dispatch_stanza(session, stanza)
                return handlestanza(session, stanza);
        end

        module:fire_event("s2s-created", { session = session });

        add_task(connect_timeout, function ()
                if session.type == "s2sin" or session.type == "s2sout" then
                        return; -- Ok, we're connected
                elseif session.type == "s2s_destroyed" then
                        return; -- Session already destroyed
                end
                -- Not connected, need to close session and clean up
                (session.log or log)("debug", "Destroying incomplete session %s->%s due to inactivity",
                session.from_host or "(unknown)", session.to_host or "(unknown)");
                session:close("connection-timeout");
        end);
end

function listener.onconnect(conn)
        conn:setoption("keepalive", opt_keepalives);
        local session = sessions[conn];
        if not session then -- New incoming connection
                session = s2s_new_incoming(conn);
                sessions[conn] = session;
                session.log("debug", "Incoming s2s connection");
                initialize_session(session);
        else -- Outgoing session connected
                session:open_stream(session.from_host, session.to_host);
        end
        session.ip = conn:ip();
end

function listener.onincoming(conn, data)
        local session = sessions[conn];
        if session then
                session.data(data);
        end
end

function listener.onstatus(conn, status)
        if status == "ssl-handshake-complete" then
                local session = sessions[conn];
                if session and session.direction == "outgoing" then
                        session.log("debug", "Sending stream header...");
                        session:open_stream(session.from_host, session.to_host);
                end
        end
end

function listener.ondisconnect(conn, err)
        local session = sessions[conn];
        if session then
                sessions[conn] = nil;
                if err and session.direction == "outgoing" and session.notopen then
                        (session.log or log)("debug", "s2s connection attempt failed: %s", err);
                        if s2sout.attempt_connection(session, err) then
                                return; -- Session lives for now
                        end
                end
                (session.log or log)("debug", "s2s disconnected: %s->%s (%s)", tostring(session.from_host), tostring(session.to_host), tostring(err or "connection closed"));
                s2s_destroy_session(session, err);
        end
end

function listener.onreadtimeout(conn)
        local session = sessions[conn];
        if session then
                return (hosts[session.host] or prosody).events.fire_event("s2s-read-timeout", { session = session });
        end
end

function listener.register_outgoing(conn, session)
        sessions[conn] = session;
        initialize_session(session);
end

function check_auth_policy(event)
        local host, session = event.host, event.session;
        local must_secure = secure_auth;

        if not must_secure and secure_domains[host] then
                must_secure = true;
        elseif must_secure and insecure_domains[host] then
                must_secure = false;
        end

        if must_secure and (session.cert_chain_status ~= "valid" or session.cert_identity_status ~= "valid") then
                module:log("warn", "Forbidding insecure connection to/from %s", host or session.ip or "(unknown host)");
                if session.direction == "incoming" then
                        session:close({ condition = "not-authorized", text = "Your server's certificate is invalid, expired, or not trusted by "..session.to_host });
                else -- Close outgoing connections without warning
                        session:close(false);
                end
                return false;
        end
end

module:hook("s2s-check-certificate", check_auth_policy, -1);

s2sout.set_listener(listener);

module:hook("server-stopping", function(event)
        local reason = event.reason;
        for _, session in pairs(sessions) do
                session:close{ condition = "system-shutdown", text = reason };
        end
end,500);



module:provides("net", {
        name = "s2s";
        listener = listener;
        default_port = 5269;
        encryption = "starttls";
        multiplex = {
                pattern = "^<.*:stream.*%sxmlns%s*=%s*(['\"])jabber:server%1.*>";
        };
});