[prosody.git] / core / s2smanager.lua

-- Prosody IM
-- Copyright (C) 2008-2009 Matthew Wild
-- Copyright (C) 2008-2009 Waqas Hussain
-- 
-- This project is MIT/X11 licensed. Please see the
-- COPYING file in the source package for more information.
--



local hosts = hosts;
local sessions = sessions;
local core_process_stanza = function(a, b) core_process_stanza(a, b); end
local add_task = require "util.timer".add_task;
local socket = require "socket";
local format = string.format;
local t_insert, t_sort = table.insert, table.sort;
local get_traceback = debug.traceback;
local tostring, pairs, ipairs, getmetatable, newproxy, error, tonumber
    = tostring, pairs, ipairs, getmetatable, newproxy, error, tonumber;

local idna_to_ascii = require "util.encodings".idna.to_ascii;
local connlisteners_get = require "net.connlisteners".get;
local wrapclient = require "net.server".wrapclient;
local modulemanager = require "core.modulemanager";
local st = require "stanza";
local stanza = st.stanza;
local nameprep = require "util.encodings".stringprep.nameprep;

local uuid_gen = require "util.uuid".generate;

local logger_init = require "util.logger".init;

local log = logger_init("s2smanager");

local sha256_hash = require "util.hashes".sha256;

local dialback_secret = uuid_gen();

local adns, dns = require "net.adns", require "net.dns";

local dns_timeout = config.get("*", "core", "dns_timeout") or 60;

incoming_s2s = {};
local incoming_s2s = incoming_s2s;

module "s2smanager"

local function compare_srv_priorities(a,b) return a.priority < b.priority or a.weight < b.weight; end

local function bounce_sendq(session)
        local sendq = session.sendq;
        if sendq then
                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", get_traceback());
                        end;
                        dummy = true;
                };
                for i, data in ipairs(sendq) do
                        local reply = data[2];
                        local xmlns = reply.attr.xmlns;
                        if not xmlns or xmlns == "jabber:client" or xmlns == "jabber:server" then
                                reply.attr.type = "error";
                                reply:tag("error", {type = "cancel"})
                                        :tag("remote-server-not-found", {xmlns = "urn:ietf:params:xml:ns:xmpp-stanzas"}):up();
                                core_process_stanza(dummy, reply);
                        end
                        sendq[i] = nil;
                end
                session.sendq = nil;
        end
end

function send_to_host(from_host, to_host, data)
        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 data.name ~= "db:verify" and ((not data.xmlns) or data.xmlns == "jabber:client" or data.xmlns == "jabber:server") then
                        (host.log or log)("debug", "trying to send over unauthed s2sout to "..to_host);
                        if not host.notopen and not host.dialback_key and host.sends2s then
                                host.log("debug", "dialback had not been initiated");
                                initiate_dialback(host);
                        end
                        
                        -- Queue stanza until we are able to send it
                        if host.sendq then t_insert(host.sendq, {tostring(data), st.reply(data)});
                        else host.sendq = { {tostring(data), st.reply(data)} }; end
                        host.log("debug", "stanza [%s] queued ", data.name);
                elseif host.type == "local" or host.type == "component" then
                        log("error", "Trying to send a stanza to ourselves??")
                        log("error", "Traceback: %s", get_traceback());
                        log("error", "Stanza: %s", tostring(data));
                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
                        host.sends2s(data);
                        host.log("debug", "stanza sent over "..host.type);
                end
        else
                log("debug", "opening a new outgoing connection for this stanza");
                local host_session = new_outgoing(from_host, to_host);
                -- Store in buffer
                host_session.sendq = { {tostring(data), st.reply(data)} };
                log("debug", "stanza [%s] queued until connection complete", tostring(data.name));
                if (not host_session.connecting) and (not host_session.conn) then
                        log("warn", "Connection to %s failed already, destroying session...", to_host);
                        destroy_session(host_session);
                end
        end
end

local open_sessions = 0;

function new_incoming(conn)
        local session = { conn = conn, type = "s2sin_unauthed", direction = "incoming", hosts = {} };
        if true then
                session.trace = newproxy(true);
                getmetatable(session.trace).__gc = function () open_sessions = open_sessions - 1; end;
        end
        open_sessions = open_sessions + 1;
        local w, log = conn.write, logger_init("s2sin"..tostring(conn):match("[a-f0-9]+$"));
        session.sends2s = function (t) log("debug", "sending: %s", tostring(t)); w(tostring(t)); end
        incoming_s2s[session] = true;
        return session;
end

function new_outgoing(from_host, to_host)
                local host_session = { to_host = to_host, from_host = from_host, notopen = true, type = "s2sout_unauthed", direction = "outgoing" };
                hosts[from_host].s2sout[to_host] = host_session;
                
                local log;
                do
                        local conn_name = "s2sout"..tostring(host_session):match("[a-f0-9]*$");
                        log = logger_init(conn_name);
                        host_session.log = log;
                end
                
                -- This is the first call, can't fail (the first step is DNS lookup)
                attempt_connection(host_session);
                
                if not host_session.sends2s then                
                        -- A sends2s which buffers data (until the stream is opened)
                        -- note that data in this buffer will be sent before the stream is authed
                        -- and will not be ack'd in any way, successful or otherwise
                        local buffer;
                        function host_session.sends2s(data)
                                if not buffer then
                                        buffer = {};
                                        host_session.send_buffer = buffer;
                                end
                                log("debug", "Buffering data on unconnected s2sout to %s", to_host);
                                buffer[#buffer+1] = data;
                                log("debug", "Buffered item %d: %s", #buffer, tostring(data));
                        end
                        
                end

                return host_session;
end


function attempt_connection(host_session, err)
        local from_host, to_host = host_session.from_host, host_session.to_host;
        local connect_host, connect_port = idna_to_ascii(to_host), 5269;
        
        if not err then -- This is our first attempt
                log("debug", "First attempt to connect to %s, starting with SRV lookup...", to_host);
                host_session.connecting = true;
                local handle;
                handle = adns.lookup(function (answer)
                        handle = nil;
                        host_session.connecting = nil;
                        if answer then
                                log("debug", to_host.." has SRV records, handling...");
                                local srv_hosts = {};
                                host_session.srv_hosts = srv_hosts;
                                for _, record in ipairs(answer) do
                                        t_insert(srv_hosts, record.srv);
                                end
                                t_sort(srv_hosts, compare_srv_priorities);
                                
                                local srv_choice = srv_hosts[1];
                                host_session.srv_choice = 1;
                                if srv_choice then
                                        connect_host, connect_port = srv_choice.target or to_host, srv_choice.port or connect_port;
                                        log("debug", "Best record found, will connect to %s:%d", connect_host, connect_port);
                                end
                        else
                                log("debug", to_host.." has no SRV records, falling back to A");
                        end
                        -- Try with SRV, or just the plain hostname if no SRV
                        local ok, err = try_connect(host_session, connect_host, connect_port);
                        if not ok then
                                if not attempt_connection(host_session, err) then
                                        -- No more attempts will be made
                                        destroy_session(host_session);
                                end
                        end
                end, "_xmpp-server._tcp."..connect_host..".", "SRV");
                
                -- Set handler for DNS timeout
                add_task(dns_timeout, function ()
                        if handle then
                                adns.cancel(handle, true);
                        end
                end);
                
                log("debug", "DNS lookup for %s sent, waiting for response before we can connect", to_host);
                return true; -- Attempt in progress
        elseif host_session.srv_hosts and #host_session.srv_hosts > host_session.srv_choice then -- Not our first attempt, and we also have SRV
                host_session.srv_choice = host_session.srv_choice + 1;
                local srv_choice = host_session.srv_hosts[host_session.srv_choice];
                connect_host, connect_port = srv_choice.target or to_host, srv_choice.port or connect_port;
                host_session.log("info", "Connection failed (%s). Attempt #%d: This time to %s:%d", tostring(err), host_session.srv_choice, connect_host, connect_port);
        else
                host_session.log("info", "Out of connection options, can't connect to %s", tostring(host_session.to_host));
                -- We're out of options
                return false;
        end
        
        if not (connect_host and connect_port) then
                -- Likely we couldn't resolve DNS
                log("warn", "Hmm, we're without a host (%s) and port (%s) to connect to for %s, giving up :(", tostring(connect_host), tostring(connect_port), tostring(to_host));
                return false;
        end
        
        return try_connect(host_session, connect_host, connect_port);
end

function try_connect(host_session, connect_host, connect_port)
        host_session.connecting = true;
        local handle;
        handle = adns.lookup(function (reply)
                handle = nil;
                host_session.connecting = nil;
                
                -- COMPAT: This is a compromise for all you CNAME-(ab)users :)
                if not (reply and reply[1] and reply[1].a) then
                        reply = dns.peek(connect_host, "CNAME", "IN");
                        while reply and reply[1] and not reply[1].a and reply[1].cname do
                                reply = dns.peek(reply[1].cname, "A", "IN") or dns.peek(reply[1].cname, "CNAME", "IN");
                        end
                end
                -- end of CNAME resolving
                
                if reply and reply[1] and reply[1].a then
                        log("debug", "DNS reply for %s gives us %s", connect_host, reply[1].a);
                        return make_connect(host_session, reply[1].a, connect_port);
                else
                        log("debug", "DNS lookup failed to get a response for %s", connect_host);
                        if not attempt_connection(host_session, "name resolution failed") then -- Retry if we can
                                log("debug", "No other records to try for %s - destroying", host_session.to_host);
                                destroy_session(host_session); -- End of the line, we can't
                        end
                end
        end, connect_host, "A", "IN");

        -- Set handler for DNS timeout
        add_task(dns_timeout, function ()
                if handle then
                        adns.cancel(handle, true);
                end
        end);
                
        return true;
end

function make_connect(host_session, connect_host, connect_port)
        host_session.log("info", "Beginning new connection attempt to %s (%s:%d)", host_session.to_host, connect_host, connect_port);
        -- Ok, we're going to try to connect
        
        local from_host, to_host = host_session.from_host, host_session.to_host;
        
        local conn, handler = socket.tcp()

        conn:settimeout(0);
        local success, err = conn:connect(connect_host, connect_port);
        if not success and err ~= "timeout" then
                log("warn", "s2s connect() to %s (%s:%d) failed: %s", host_session.to_host, connect_host, connect_port, err);
                return false, err;
        end
        
        local cl = connlisteners_get("xmppserver");
        conn = wrapclient(conn, connect_host, connect_port, cl, cl.default_mode or 1, hosts[from_host].ssl_ctx, false );
        host_session.conn = conn;
        
        -- Register this outgoing connection so that xmppserver_listener knows about it
        -- otherwise it will assume it is a new incoming connection
        cl.register_outgoing(conn, host_session);
        
        local w = conn.write;
        host_session.sends2s = function (t) log("debug", "sending: %s", tostring(t)); w(tostring(t)); end
        
        conn.write(format([[<stream:stream xmlns='jabber:server' xmlns:db='jabber:server:dialback' xmlns:stream='http://etherx.jabber.org/streams' from='%s' to='%s' version='1.0' xml:lang='en'>]], from_host, to_host));
        log("debug", "Connection attempt in progress...");
        return true;
end

function streamopened(session, attr)
        local send = session.sends2s;
        
        -- TODO: #29: SASL/TLS on s2s streams
        session.version = 0; --tonumber(attr.version) or 0;
        
        if session.version >= 1.0 and not (attr.to and attr.from) then
                log("warn", (session.to_host or "(unknown)").." failed to specify 'to' or 'from' hostname as per RFC");
        end
        
        if session.direction == "incoming" then
                -- Send a reply stream header
                session.to_host = attr.to and nameprep(attr.to);
                session.from_host = attr.from and nameprep(attr.from);
        
                session.streamid = uuid_gen();
                (session.log or log)("debug", "incoming s2s received <stream:stream>");
                send("<?xml version='1.0'?>");
                send(stanza("stream:stream", { xmlns='jabber:server', ["xmlns:db"]='jabber:server:dialback', 
                                ["xmlns:stream"]='http://etherx.jabber.org/streams', id=session.streamid, from=session.to_host }):top_tag());
                if session.to_host and not hosts[session.to_host] then
                        -- Attempting to connect to a host we don't serve
                        session:close({ condition = "host-unknown"; text = "This host does not serve "..session.to_host });
                        return;
                end
                if session.version >= 1.0 then
                        send(st.stanza("stream:features")
                                        :tag("dialback", { xmlns='urn:xmpp:features:dialback' }):tag("optional"):up():up());
                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;
        
                -- 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 not session.dialback_verifying then
                        initiate_dialback(session);
                else
                        mark_connected(session);
                end
        end

        session.notopen = nil;
end

function streamclosed(session)
        (session.log or log)("debug", "</stream:stream>");
        if session.sends2s then
                session.sends2s("</stream:stream>");
        end
        session.notopen = true;
end

function initiate_dialback(session)
        -- generate dialback key
        session.dialback_key = generate_dialback(session.streamid, session.to_host, session.from_host);
        session.sends2s(format("<db:result from='%s' to='%s'>%s</db:result>", session.from_host, session.to_host, session.dialback_key));
        session.log("info", "sent dialback key on outgoing s2s stream");
end

function generate_dialback(id, to, from)
        return sha256_hash(id..to..from..dialback_secret, true);
end

function verify_dialback(id, to, from, key)
        return key == generate_dialback(id, to, from);
end

function make_authenticated(session, host)
        if session.type == "s2sout_unauthed" then
                session.type = "s2sout";
        elseif session.type == "s2sin_unauthed" then
                session.type = "s2sin";
                if host then
                        session.hosts[host].authed = true;
                end
        elseif session.type == "s2sin" and host then
                session.hosts[host].authed = true;
        else
                return false;
        end
        session.log("debug", "connection %s->%s is now authenticated", session.from_host or "(unknown)", session.to_host or "(unknown)");
        
        mark_connected(session);
        
        return true;
end

function mark_connected(session)
        local sendq, send = session.sendq, session.sends2s;
        
        local from, to = session.from_host, session.to_host;
        
        session.log("info", session.direction.." s2s connection "..from.."->"..to.." complete");
        
        local send_to_host = send_to_host;
        function session.send(data) send_to_host(to, from, data); end
        
        
        if session.direction == "outgoing" then
                if sendq then
                        session.log("debug", "sending "..#sendq.." queued stanzas across new outgoing connection to "..session.to_host);
                        for i, data in ipairs(sendq) do
                                send(data[1]);
                                sendq[i] = nil;
                        end
                        session.sendq = nil;
                end
                
                session.srv_hosts = nil;
        end
end

function destroy_session(session)
        (session.log or log)("info", "Destroying "..tostring(session.direction).." session "..tostring(session.from_host).."->"..tostring(session.to_host));
        
        if session.direction == "outgoing" then
                hosts[session.from_host].s2sout[session.to_host] = nil;
                bounce_sendq(session);
        elseif session.direction == "incoming" then
                incoming_s2s[session] = nil;
        end
        
        for k in pairs(session) do
                if k ~= "trace" then
                        session[k] = nil;
                end
        end
end

return _M;