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xwords/xwords4/relay/states.cpp
ehouse 6835b6d1eb New scheme for accepting and limiting reconnections. Now device must 
send player counts, local and expected.  Based on these the relay
accepts connections, declares the game full and ready for message
forwarding, and decides whether to accept a reconnect.
2005-10-02 15:39:38 +00:00

290 lines
13 KiB
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/* -*-mode: C; fill-column: 78; c-basic-offset: 4; -*- */
/*
* Copyright 2005 by Eric House (fixin@peak.org). All rights reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
#include "assert.h"
#include "states.h"
#include "xwrelay_priv.h"
typedef struct StateTable {
XW_RELAY_STATE stateStart;
XW_RELAY_EVENT stateEvent;
XW_RELAY_ACTION stateAction;
XW_RELAY_STATE stateEnd; /* Do I need this? Or does the code that
performs the action determine the state? */
} StateTable;
/* Connecting. The problem is that we don't know how many devices to expect.
So hosts connect and get a response. Hosts send messages to be forwarded.
We may or may not have an ID for the recipient host. If we do, we forward.
If we don't, we drop. No big deal. So is there any difference between
CONNECTING and CONNECTED? I don't think so. Messages come in and we try
to forward. Connection requests come in and we accept them if the host in
question is unknown. NOT QUITE. There's a DOS vulnerability there. It's
best if we can put the game in a state where others can't connect, if the
window where new devices can sign in using a given cookie is fairly small.
New rules on accepting connections and reconnections:
- Connect and reconnect messages contain nPlayersHere (local) and
nPlayersTotal params.
- On connect action, we either note the total expected, or increase the
total we have. Ditto on reconnect. On disconnect, we take the departing
hosts marbles away from the game.
- We only accept [re]connections when we're missing players, and we only
forward messages when all devices/players are accounted for. There's a
notification sent when the last shows up, so devices can send pending
messages at that time.
- There's at least one bug with this scheme: we don't know how many players
to expect until the server shows up, so we'll keep accepting clients
until that happens. Probably need a config variable that sets an upper
bound on the number of players.
*/
StateTable g_stateTable[] = {
{ XW_ST_INITED, XW_EVT_CONNECTMSG, XW_ACT_CHKCOUNTS, XW_ST_CHKCOUNTS_INIT },
{ XW_ST_CHKCOUNTS_INIT, XW_EVT_OKTOSEND, XW_ACT_SEND_1ST_RSP, XW_ST_CHK_ALLHERE },
{ XW_ST_CHKCOUNTS_INIT, XW_EVT_COUNTSBAD, XW_ACT_REJECT, XW_ST_INITED },
{ XW_ST_CONNECTING, XW_EVT_CONNECTMSG, XW_ACT_CHKCOUNTS, XW_ST_CHKCOUNTS },
{ XW_ST_CHKCOUNTS, XW_EVT_OKTOSEND, XW_ACT_SEND_1ST_RSP, XW_ST_CHK_ALLHERE },
{ XW_ST_CHKCOUNTS, XW_EVT_COUNTSBAD, XW_ACT_REJECT, XW_ST_CONNECTING },
{ XW_ST_MISSING, XW_EVT_CONNECTMSG, XW_ACT_CHKCOUNTS, XW_ST_CHKCOUNTS_MISS },
{ XW_ST_CHKCOUNTS_MISS, XW_EVT_OKTOSEND, XW_ACT_SEND_1ST_RSP, XW_ST_CHK_2ND_ALLHERE },
{ XW_ST_CHKCOUNTS_MISS, XW_EVT_COUNTSBAD, XW_ACT_REJECT, XW_ST_MISSING },
{ XW_ST_CONNECTING, XW_EVT_CONNECTMSG, XW_ACT_SEND_RSP, XW_ST_CHK_ALLHERE },
{ XW_ST_CHK_ALLHERE, XW_EVT_ALLHERE, XW_ACT_SENDALLHERE, XW_ST_ALLCONNECTED },
{ XW_ST_CHK_ALLHERE, XW_EVT_SOMEMISSING, XW_ACT_NONE, XW_ST_CONNECTING },
{ XW_ST_ALLCONNECTED, XW_EVT_DISCONNECTMSG, XW_ACT_DISCONNECT, XW_ST_MISSING },
{ XW_ST_CONNECTING, XW_EVT_DISCONNECTMSG, XW_ACT_DISCONNECT, XW_ST_CONNECTING },
{ XW_ST_MISSING, XW_EVT_DISCONNECTMSG, XW_ACT_DISCONNECT, XW_ST_MISSING },
{ XW_ST_MISSING, XW_EVT_NOMORESOCKETS, XW_ACT_NONE, XW_ST_DEAD },
{ XW_ST_CONNECTING, XW_EVT_NOMORESOCKETS, XW_ACT_NONE, XW_ST_DEAD },
{ XW_ST_INITED, XW_EVT_RECONNECTMSG, XW_ACT_SEND_RERSP, XW_ST_CHK_2ND_ALLHERE },
{ XW_ST_MISSING, XW_EVT_RECONNECTMSG, XW_ACT_SEND_RERSP, XW_ST_CHK_2ND_ALLHERE },
{ XW_ST_CHK_2ND_ALLHERE, XW_EVT_ALLHERE, XW_ACT_2ND_SNDALLHERE,XW_ST_ALLCONNECTED },
{ XW_ST_CHK_2ND_ALLHERE, XW_EVT_SOMEMISSING, XW_ACT_NONE, XW_ST_MISSING },
{ XW_ST_CONNECTING, XW_EVT_REMOVESOCKET, XW_ACT_REMOVESOCKET, XW_ST_CONNECTING },
{ XW_ST_ALLCONNECTED, XW_EVT_REMOVESOCKET, XW_ACT_REMOVESOCKET, XW_ST_MISSING },
{ XW_ST_MISSING, XW_EVT_REMOVESOCKET, XW_ACT_REMOVESOCKET, XW_ST_MISSING },
{ XW_ST_ALLCONNECTED, XW_EVT_HEARTFAILED, XW_ACT_HEARTDISCONNECT, XW_ST_MISSING },
{ XW_ST_CONNECTING, XW_EVT_HEARTFAILED, XW_ACT_HEARTDISCONNECT, XW_ST_CONNECTING },
{ XW_ST_MISSING, XW_EVT_HEARTFAILED, XW_ACT_HEARTDISCONNECT, XW_ST_MISSING },
/* Heartbeat arrived */
{ XW_ST_CONNECTING, XW_EVT_HEARTRCVD, XW_ACT_NOTEHEART, XW_ST_CONNECTING },
{ XW_ST_ALLCONNECTED, XW_EVT_HEARTRCVD, XW_ACT_NOTEHEART, XW_ST_ALLCONNECTED },
{ XW_ST_MISSING, XW_EVT_HEARTRCVD, XW_ACT_NOTEHEART, XW_ST_MISSING },
/* Connect timer */
{ XW_ST_CONNECTING, XW_EVT_CONNTIMER, XW_ACT_TIMERDISCONNECT, XW_ST_DEAD },
{ XW_ST_ALLCONNECTED, XW_EVT_CONNTIMER, XW_ACT_NONE, XW_ST_ALLCONNECTED },
{ XW_ST_CONNECTING, XW_EVT_NOTIFYDISCON,XW_ACT_NOTIFYDISCON, XW_ST_CONNECTING },
{ XW_ST_ALLCONNECTED, XW_EVT_NOTIFYDISCON,XW_ACT_NOTIFYDISCON, XW_ST_MISSING },
{ XW_ST_MISSING, XW_EVT_NOTIFYDISCON,XW_ACT_NOTIFYDISCON, XW_ST_DEAD },
{ XW_ST_DEAD, XW_EVT_NOTIFYDISCON,XW_ACT_NOTIFYDISCON, XW_ST_DEAD },
/* This is our bread-n-butter */
{ XW_ST_ALLCONNECTED, XW_EVT_FORWARDMSG, XW_ACT_FWD, XW_ST_ALLCONNECTED },
{ XW_ST_DEAD, XW_EVT_REMOVESOCKET, XW_ACT_REMOVESOCKET, XW_ST_DEAD },
#if 0
/* Initial msg comes in. Managing object created in init state, sends response */
{ XW_ST_INITED, XW_EVT_CONNECTMSG, XW_ACT_SEND_1ST_RSP, XW_ST_CONNECTING },
{ XW_ST_INITED, XW_EVT_RECONNECTMSG, XW_ACT_SEND_1ST_RERSP,XW_ST_CONNECTING },
/* Another connect msg comes in */
{ XW_ST_CONNECTING, XW_EVT_CONNECTMSG, XW_ACT_SEND_RSP, XW_ST_CONNECTING },
{ XW_ST_CONNECTING, XW_EVT_RECONNECTMSG, XW_ACT_SEND_RERSP, XW_ST_CONNECTING },
{ XW_ST_MISSING, XW_EVT_CONNECTMSG, XW_ACT_SEND_RSP, XW_ST_CONNECTING },
{ XW_ST_MISSING, XW_EVT_RECONNECTMSG, XW_ACT_SEND_RERSP, XW_ST_CONNECTING },
/* Disconnect. */
{ XW_ST_ALLCONNECTED, XW_EVT_DISCONNECTMSG, XW_ACT_DISCONNECT, XW_ST_MISSING },
{ XW_ST_CONNECTING, XW_EVT_DISCONNECTMSG, XW_ACT_DISCONNECT, XW_ST_CONNECTING },
{ XW_ST_MISSING, XW_EVT_DISCONNECTMSG, XW_ACT_DISCONNECT, XW_ST_MISSING },
{ XW_ST_MISSING, XW_EVT_NOMORESOCKETS, XW_ACT_NONE, XW_ST_DEAD },
/* Forward requests while not locked are ok -- but we must check that the
target is actually present. If no socket available must drop the message */
{ XW_ST_CONNECTING, XW_EVT_FORWARDMSG, XW_ACT_CHECKDEST, XW_ST_CHECKINGDEST },
{ XW_ST_CHECKINGDEST, XW_EVT_DESTOK, XW_ACT_CHECK_CAN_LOCK, XW_ST_CHECKING_CAN_LOCK },
{ XW_ST_CHECKING_CAN_LOCK, XW_EVT_CAN_LOCK, XW_ACT_FWD, XW_ST_ALLCONNECTED },
{ XW_ST_CHECKING_CAN_LOCK, XW_EVT_CANT_LOCK, XW_ACT_FWD, XW_ST_CONNECTING },
{ XW_ST_CHECKINGDEST, XW_EVT_DESTBAD, XW_ACT_NONE, XW_ST_CONNECTING },
/* Timeout before all connected */
{ XW_ST_ALLCONNECTED, XW_EVT_HEARTFAILED, XW_ACT_HEARTDISCONNECT, XW_ST_MISSING },
{ XW_ST_CONNECTING, XW_EVT_HEARTFAILED, XW_ACT_HEARTDISCONNECT, XW_ST_CONNECTING },
{ XW_ST_MISSING, XW_EVT_HEARTFAILED, XW_ACT_HEARTDISCONNECT, XW_ST_MISSING },
{ XW_ST_CONNECTING, XW_EVT_REMOVESOCKET, XW_ACT_REMOVESOCKET, XW_ST_CONNECTING },
{ XW_ST_ALLCONNECTED, XW_EVT_REMOVESOCKET, XW_ACT_REMOVESOCKET, XW_ST_MISSING },
{ XW_ST_MISSING, XW_EVT_REMOVESOCKET, XW_ACT_REMOVESOCKET, XW_ST_MISSING },
{ XW_ST_CONNECTING, XW_EVT_NOMORESOCKETS, XW_ACT_NONE, XW_ST_DEAD },
{ XW_ST_DEAD, XW_EVT_NOMORESOCKETS, XW_ACT_NONE, XW_ST_DEAD },
/* This is the entry we'll use most of the time */
{ XW_ST_ALLCONNECTED, XW_EVT_FORWARDMSG, XW_ACT_FWD, XW_ST_ALLCONNECTED },
/* Heartbeat arrived */
{ XW_ST_CONNECTING, XW_EVT_HEARTRCVD, XW_ACT_NOTEHEART, XW_ST_CONNECTING },
{ XW_ST_ALLCONNECTED, XW_EVT_HEARTRCVD, XW_ACT_NOTEHEART, XW_ST_ALLCONNECTED },
{ XW_ST_MISSING, XW_EVT_HEARTRCVD, XW_ACT_NOTEHEART, XW_ST_MISSING },
/* I think we need a state XW_ST_SOMEMISSING. The game can't be played,
but we're open to XWRELAY_RECONNECT (but not to XWRELAY_CONNECT) */
{ XW_ST_CONNECTING, XW_EVT_NOTIFYDISCON, XW_ACT_NOTIFYDISCON, XW_ST_CONNECTING },
{ XW_ST_ALLCONNECTED, XW_EVT_NOTIFYDISCON, XW_ACT_NOTIFYDISCON, XW_ST_MISSING },
{ XW_ST_MISSING, XW_EVT_NOTIFYDISCON, XW_ACT_NOTIFYDISCON, XW_ST_DEAD },
{ XW_ST_DEAD, XW_EVT_NOTIFYDISCON, XW_ACT_NOTIFYDISCON, XW_ST_DEAD },
{ XW_ST_DEAD, XW_EVT_REMOVESOCKET, XW_ACT_REMOVESOCKET, XW_ST_DEAD },
#endif
// { XW_ST_DEAD, XW_EVT_ANY, XW_ACT_NONE, XW_ST_DEAD },
/* Reconnect. Just like a connect but cookieID is supplied. Can it
happen in the middle of a game when state is XW_ST_ALLCONNECTED? */
/* Marks end of table */
{ XW_ST_NONE, XW_EVT_NONE, XW_ACT_NONE, XW_ST_NONE }
};
int
getFromTable( XW_RELAY_STATE curState, XW_RELAY_EVENT curEvent,
XW_RELAY_ACTION* takeAction, XW_RELAY_STATE* nextState )
{
StateTable* stp = g_stateTable;
while ( stp->stateStart != XW_ST_NONE ) {
if ( stp->stateStart == curState ) {
if ( stp->stateEvent == curEvent || stp->stateEvent == XW_EVT_ANY ) {
*takeAction = stp->stateAction;
*nextState = stp->stateEnd;
return 1;
}
}
++stp;
}
logf( "==> ERROR :: unable to find transition from %s on event %s",
stateString(curState), eventString(curEvent) );
return 0;
} /* getFromTable */
#define CASESTR(s) case s: return #s
char*
stateString( XW_RELAY_STATE state )
{
switch( state ) {
CASESTR(XW_ST_NONE);
CASESTR(XW_ST_INITED);
CASESTR(XW_ST_CONNECTING);
CASESTR(XW_ST_ALLCONNECTED);
CASESTR(XW_ST_WAITING_RECON);
CASESTR(XW_ST_DEAD);
CASESTR(XW_ST_CHECKING_CONN);
CASESTR(XW_ST_CHECKINGDEST);
CASESTR(XW_ST_CHECKING_CAN_LOCK);
CASESTR(XW_ST_MISSING);
CASESTR(XW_ST_CHK_ALLHERE);
CASESTR(XW_ST_CHK_2ND_ALLHERE);
CASESTR(XW_ST_CHKCOUNTS_INIT);
CASESTR(XW_ST_CHKCOUNTS_MISS);
CASESTR(XW_ST_CHKCOUNTS);
}
assert(0);
return "";
}
char*
eventString( XW_RELAY_EVENT evt )
{
switch( evt ) {
CASESTR(XW_EVT_NONE);
CASESTR(XW_EVT_CONNECTMSG);
CASESTR(XW_EVT_RECONNECTMSG);
CASESTR(XW_EVT_DISCONNECTMSG);
CASESTR(XW_EVT_FORWARDMSG);
CASESTR(XW_EVT_HEARTRCVD);
CASESTR(XW_EVT_CONNTIMER);
CASESTR(XW_EVT_HEARTFAILED);
CASESTR(XW_EVT_DESTOK);
CASESTR(XW_EVT_DESTBAD);
CASESTR(XW_EVT_CAN_LOCK);
CASESTR(XW_EVT_CANT_LOCK);
CASESTR(XW_EVT_ANY);
CASESTR(XW_EVT_REMOVESOCKET);
CASESTR(XW_EVT_NOMORESOCKETS);
CASESTR(XW_EVT_NOTIFYDISCON);
CASESTR(XW_EVT_ALLHERE);
CASESTR(XW_EVT_SOMEMISSING);
CASESTR(XW_EVT_OKTOSEND);
CASESTR(XW_EVT_COUNTSBAD);
}
assert(0);
return "";
}
char*
actString( XW_RELAY_ACTION act )
{
switch ( act ) {
CASESTR(XW_ACT_NONE);
CASESTR(XW_ACT_SEND_1ST_RSP);
CASESTR(XW_ACT_SEND_1ST_RERSP);
CASESTR(XW_ACT_CHKCOUNTS);
CASESTR(XW_ACT_REJECT);
CASESTR(XW_ACT_SEND_RSP);
CASESTR(XW_ACT_SEND_RERSP);
CASESTR(XW_ACT_SENDALLHERE);
CASESTR(XW_ACT_2ND_SNDALLHERE);
CASESTR(XW_ACT_FWD);
CASESTR(XW_ACT_NOTEHEART);
CASESTR(XW_ACT_DISCONNECTALL);
CASESTR(XW_ACT_TIMERDISCONNECT);
CASESTR(XW_ACT_CHECKDEST);
CASESTR(XW_ACT_DISCONNECT);
CASESTR(XW_ACT_NOTIFYDISCON);
CASESTR(XW_ACT_REMOVESOCKET);
CASESTR(XW_ACT_CHECK_CAN_LOCK);
CASESTR(XW_ACT_HEARTDISCONNECT);
}
assert(0);
return "";
}
#undef CASESTR
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