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xwords/relay/xwrelay.cpp
ehouse a26549afa9 Pass protocol version code with connect request, and return error if 
it isn't what relay can handle.  Report error to user.
2005-07-06 01:36:52 +00:00

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11 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.
*/
//////////////////////////////////////////////////////////////////////////////
//
// This program is a *very rough* cut at a message forwarding server that's
// meant to sit somewhere that cellphones can reach and forward packets across
// connections so that they can communicate. It exists to work around the
// fact that many cellular carriers prevent direct incoming connections from
// reaching devices on their networks. It's meant for Crosswords, but might
// be useful for other things. It also needs a lot of work, and I hacked it
// up before making an exhaustive search for other alternatives.
//
//////////////////////////////////////////////////////////////////////////////
#include <stdio.h>
#include <unistd.h>
#include <netdb.h> /* gethostbyname */
#include <errno.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <unistd.h>
#include <fcntl.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdlib.h>
#include <string.h>
#include <pthread.h>
#include <assert.h>
#include <sys/select.h>
#include <stdarg.h>
#include <sys/time.h>
#include "xwrelay.h"
#include "cref.h"
#include "ctrl.h"
#include "mlock.h"
#include "tpool.h"
#define N_WORKER_THREADS 5
#define MILLIS 1000000
void
logf( const char* format, ... )
{
FILE* where = stderr;
struct tm* timp;
struct timeval tv;
struct timezone tz;
gettimeofday( &tv, &tz );
timp = localtime( &tv.tv_sec );
pthread_t me = pthread_self();
fprintf( where, "<%lx>%d:%d:%d: ", me, timp->tm_hour, timp->tm_min,
timp->tm_sec );
va_list ap;
va_start( ap, format );
vfprintf( where, format, ap );
va_end(ap);
fprintf( where, "\n" );
} /* logf */
static unsigned short
getNetShort( unsigned char** bufpp )
{
unsigned short tmp;
memcpy( &tmp, *bufpp, 2 );
*bufpp += 2;
return ntohs( tmp );
} /* getNetShort */
static unsigned short
getNetLong( unsigned char** bufpp )
{
unsigned long tmp;
memcpy( &tmp, *bufpp, sizeof(tmp) );
*bufpp += sizeof(tmp);
assert( sizeof(tmp) == 4 );
return ntohl( tmp );
} /* getNetLong */
static void
processHeartbeat( unsigned char* buf, int bufLen, int socket )
{
CookieID cookieID = getNetLong( &buf );
HostID hostID = getNetShort( &buf );
logf( "processHeartbeat: cookieID 0x%lx, hostID 0x%x", cookieID, hostID );
CookieRef* cref = get_cookieRef( cookieID );
if ( cref != NULL ) {
cref->HandleHeartbeat( hostID, socket );
} else {
killSocket( socket, "no cref for socket" );
}
} /* processHeartbeat */
static int
readCookie( unsigned char** bufp, const unsigned char* end,
char* outBuf )
{
unsigned char clen = **bufp;
++*bufp;
if ( *bufp < end && clen > 0 && clen < MAX_COOKIE_LEN ) {
memcpy( outBuf, *bufp, clen );
outBuf[clen] = '\0';
*bufp += clen;
return 1;
}
return 0;
} /* readCookie */
static int
flagsOK( unsigned char flags )
{
return flags == XWRELAY_PROTO_VERSION;
} /* flagsOK */
static void
denyConnection( int socket )
{
unsigned char buf[2];
buf[0] = XWRELAY_CONNECTDENIED;
buf[1] = XWRELAY_ERROR_BADPROTO;
send_with_length_unsafe( socket, buf, sizeof(buf) );
}
/* No mutex here. Caller better be ensuring no other thread can access this
* socket. */
int
send_with_length_unsafe( int socket, unsigned char* buf, int bufLen )
{
int ok = 0;
unsigned short len = htons( bufLen );
ssize_t nSent = send( socket, &len, 2, 0 );
if ( nSent == 2 ) {
nSent = send( socket, buf, bufLen, 0 );
if ( nSent == bufLen ) {
logf( "sent %d bytes on socket %d", nSent, socket );
ok = 1;
}
}
return ok;
} /* send_with_length_unsafe */
/* A CONNECT message from a device gives us the hostID and socket we'll
* associate with one participant in a relayed session. We'll store this
* information with the cookie where other participants can find it when they
* arrive.
*
* What to do if we already have a game going? In that case the connection ID
* passed in will be non-zero. If the device can be associated with an
* ongoing game, with its new socket, associate it and forward any messages
* outstanding. Otherwise close down the socket. And maybe the others in the
* game?
*/
static void
processConnect( unsigned char* bufp, int bufLen, int socket )
{
char cookie[MAX_COOKIE_LEN+1];
unsigned char* end = bufp + bufLen;
logf( "processConnect" );
unsigned char flags = *bufp++;
if ( flagsOK( flags ) ) {
if ( readCookie( &bufp, end, cookie ) ) {
HostID srcID;
CookieID cookieID;
if ( bufp + sizeof(srcID) + sizeof(cookieID) == end ) {
srcID = getNetShort( &bufp );
cookieID = getNetLong( &bufp );
CookieRef* cref = get_make_cookieRef( cookie, cookieID );
assert( cref != NULL );
cref->Connect( socket, srcID );
}
}
} else {
denyConnection( socket );
}
} /* processConnect */
void
killSocket( int socket, char* why )
{
logf( "killSocket(%d): %s", socket, why );
SocketMgr::RemoveSocketRefs( socket );
/* Might want to kill the thread it belongs to if we're not in it,
e.g. when unable to write to another socket. */
logf( "killSocket done" );
}
time_t
now()
{
return (unsigned long)time(NULL);
}
/* forward the message. Need only change the command after looking up the
* socket and it's ready to go. */
static int
forwardMessage( unsigned char* buf, int buflen, int srcSocket )
{
int success = 0;
unsigned char* bufp = buf + 1; /* skip cmd */
CookieID cookieID = getNetLong( &bufp );
logf( "cookieID = %d", cookieID );
CookieRef* cref = get_cookieRef( cookieID );
if ( cref != NULL ) {
HostID src = getNetShort( &bufp );
HostID dest = getNetShort( &bufp );
cref->Forward( src, dest, buf, buflen );
success = 1;
}
return success;
} /* forwardMessage */
static void
processMessage( unsigned char* buf, int bufLen, int socket )
{
XWRELAY_Cmd cmd = *buf;
switch( cmd ) {
case XWRELAY_CONNECT:
logf( "processMessage got XWRELAY_CONNECT" );
processConnect( buf+1, bufLen-1, socket );
break;
case XWRELAY_CONNECTRESP:
logf( "bad: processMessage got XWRELAY_CONNECTRESP" );
break;
case XWRELAY_MSG_FROMRELAY:
logf( "bad: processMessage got XWRELAY_MSG_FROMRELAY" );
break;
case XWRELAY_HEARTBEAT:
logf( "processMessage got XWRELAY_HEARTBEAT" );
processHeartbeat( buf + 1, bufLen - 1, socket );
break;
case XWRELAY_MSG_TORELAY:
logf( "processMessage got XWRELAY_MSG_TORELAY" );
if ( !forwardMessage( buf, bufLen, socket ) ) {
killSocket( socket, "couldn't forward message" );
} else {
}
break;
default:
assert(0);
}
} /* processMessage */
static int
make_socket( unsigned long addr, unsigned short port )
{
int sock = socket( AF_INET, SOCK_STREAM, 0 );
struct sockaddr_in sockAddr;
sockAddr.sin_family = AF_INET;
sockAddr.sin_addr.s_addr = htonl(addr);
sockAddr.sin_port = htons(port);
int result = bind( sock, (struct sockaddr*)&sockAddr, sizeof(sockAddr) );
if ( result != 0 ) {
logf( "exiting: unable to bind port %d: %d, errno = %d\n",
port, result, errno );
return -1;
}
logf( "bound socket %d on port %d", sock, port );
result = listen( sock, 5 );
if ( result != 0 ) {
logf( "exiting: unable to listen: %d, errno = %d\n", result, errno );
return -1;
}
return sock;
} /* make_socket */
static void
sighandler( int signal )
{
logf( "sighandler" );
vector<int> victims;
CheckHeartbeats( now(), &victims );
unsigned int i;
for ( i = 0; i < victims.size(); ++i ) {
killSocket( victims[i], "heartbeat check failed" );
}
logf( "sighandler done" );
} /* sighandler */
int main( int argc, char** argv )
{
int port = 10999;
if ( argc > 1 ) {
port = atoi( argv[1] );
}
/* Open a listening socket. For each received message, fork a thread into
which relevant stuff is passed. */
int listener = make_socket( INADDR_ANY, port );
if ( listener == -1 ) {
exit( 1 );
}
int control = make_socket( INADDR_LOOPBACK, port + 1 );
if ( control == -1 ) {
exit( 1 );
}
/* generate a signal after n milliseconds, then every m milliseconds */
(void)signal( SIGALRM, sighandler );
(void)ualarm( 2 * HEARTBEAT * MILLIS, 2 * HEARTBEAT* MILLIS );
XWThreadPool* tPool = XWThreadPool::GetTPool();
tPool->Setup( N_WORKER_THREADS, processMessage );
/* set up select call */
fd_set rfds;
for ( ; ; ) {
FD_ZERO(&rfds);
FD_SET( listener, &rfds );
FD_SET( control, &rfds );
int highest = listener;
if ( control > listener ) {
highest = control;
}
++highest;
int retval = select( highest, &rfds, NULL, NULL, NULL );
if ( retval < 0 ) {
logf( "errno: %d", errno );
} else {
if ( FD_ISSET( listener, &rfds ) ) {
struct sockaddr_in newaddr;
socklen_t siz = sizeof(newaddr);
int newSock = accept( listener, (sockaddr*)&newaddr, &siz );
unsigned long remoteIP = newaddr.sin_addr.s_addr;
logf( "accepting connection from 0x%lx", ntohl( remoteIP ) );
tPool->AddSocket( newSock );
--retval;
}
if ( FD_ISSET( control, &rfds ) ) {
run_ctrl_thread( control );
--retval;
}
assert( retval == 0 );
}
}
close( listener );
close( control );
return 0;
} // main
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