connections.c

/*
 * $Id: connections.c,v 0.19 1992/06/11 14:32:54 ceder Exp $
 * Copyright (C) 1991  Lysator Academic Computer Association.
 *
 * This file is part of the LysKOM server.
 * 
 * LysKOM 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 1, or (at your option) 
 * any later version.
 * 
 * LysKOM 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 LysKOM; see the file COPYING.  If not, write to
 * Lysator, c/o ISY, Linkoping University, S-581 83 Linkoping, SWEDEN,
 * or the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, 
 * MA 02139, USA.
 *
 * Please mail bug reports to bug-lyskom@lysator.liu.se. 
 */
/*
 * connections.c
 *
 * Denna fil inneh}ller niv}n ovanf|r isc.
 *
 * Created by Willf|r 31/3-90. Mostly written by ceder.
 */

static char *rcsid = "$Id: connections.c,v 0.19 1992/06/11 14:32:54 ceder Exp $";


#include <errno.h>
#include <setjmp.h>
#include <sys/types.h>
#include <sys/file.h>
#include <sys/stat.h>
#include <time.h>
#include <sys/time.h>
#include <string.h>

#include "s-string.h"
#include <kom-types.h>
#include "lyskomd.h"
#include <config.h>
#include <debug.h>
#include "end-of-atomic.h"
#include "log.h"
#include <services.h>
#include "isc-interface.h"
#include <kom-errno.h>
#include "com.h"
#include "connections.h"
#include "prot-a-parse.h"
#include "prot-a-output.h"
#include "prot-a.h"
#include <server/smalloc.h>
#include "prot-a-parse-arg.h"
#include "isc-parse.h"
#include "cache.h"
#include "send-async.h"
#include "mux.h"
#include "mux-parse.h"
#include "internal-connections.h"
#include "rfc931.h"

IscMaster      * kom_server_mcb    = NULL;
Connection     * active_connection = NULL;

/*
 * This is set TRUE when the server should be closed. It is checked
 * each time around the main loop. It is set if someone with enough
 * privileges issues a `shutdown', or of lyskomd receives a SIGHUP.
 * This not an abort: all data is saved before we exit.
 */
volatile Bool	 go_and_die = FALSE;

/*
 * Once upon a time the entire database was always held in core, and
 * saved to disk when we got a SIGUSR1 signal. Nowadays the server
 * keeps track of the time itself and saves at appropriate intervalls.
 * It does still write some statistics when it get a SIGUSR1 signal.
 * The signal handler sets do_sync_db. The name is retained for
 * historical reasons.
 */
volatile Bool	 do_sync_db = FALSE;

jmp_buf 	 parse_env;


const Fnc_descriptor fnc_defs[]={
#include "fnc-def-init.incl"
};

u_long service_statistics[sizeof (fnc_defs) / sizeof (Fnc_descriptor)];

BUGDECL;



static void
logout_client(Connection *cp)
{
    Connection *real_active_connection;

    if ( active_connection != NULL )
    {
	log("BUGCHK: logout_client(%d): connection %d is active.\n",
	    cp->session_no, active_connection->session_no);
    }
    
    switch (cp->magic)
    {
    case CONN_MAGIC_ALLOC:
        break;

    case CONN_MAGIC_FREE:
	log("LOGOUT_CLIENT: Trying to free freed Connection - ignored!\n");
	return;

    default:
	restart_kom("LOGOUT_CLIENT: Bad magic number\n");
    }

    if ( cp->pers_no != 0 )
    {
	real_active_connection = active_connection; /* Shouldn't be needed +++ */
	active_connection = cp;
	logout();
	active_connection = real_active_connection;
    }

    switch(cp->protocol)
    {
    case 0:			/* Hasn't yet allocated any protocol. */
	break;
	
    case 'A':
	prot_a_destruct(cp);
	break;
	
    default:
	restart_kom("logout_client(): Bad protocol.\n");
    }

    mux_close(cp);		/* Close fd's. Clear mux and isc structures. */

    kill_client(cp);		/* Free the Connection */
}

/*
 * This function is part of the shutdown tidy-up sequence.
 */
void
logout_all_clients(void)
{
    Session_no sess = 0;
    Connection *conn;
    
    while ( (sess = traverse_connections (sess)) != 0)
    {
	conn = get_conn_by_number (sess);

	if ( conn == NULL )
	    restart_kom("logout_all_clients(): cant get session %d.\n",
			sess);
	else
	    logout_client (conn);
    }

    if ( traverse_connections (0) != 0)
	restart_kom("logout_all_clients(): traverse_connections(0) == %d.\n",
		    traverse_connections(0));
}

    
    

    
/*
 * Call a function in services.c. A pointer to the result is returned.
 * The pointer points to static data which is overwritten on each call.
 */
static Success
call_function (Connection  * client,
	       Result_holder   * res)     /* This is a union. */
{
    Success	status=FAILURE;	/* OK if the call was successful. */

    if ( active_connection != NULL )
    {
	log("call_function(%d): active_connection = %d",
	    client->session_no, active_connection->session_no);
    }
    
    active_connection = client;

    service_statistics[client->function]++;

#include "call-switch.incl"

    active_connection = NULL;

    return status;
}


static void
parse_packet(Connection *client)
{
    if ( client->protocol == '\0' ) /* Not known yet. */
    {
	client->protocol = parse_char(client);
	switch(client->protocol)
	{
	case 'A':
	    prot_a_init(client);
	    break;

	default:
	    client->protocol = '\0';
	    mux_printf(client,
		    "%%%%LysKOM unsupported protocol.\n");
	    mux_flush(client);
	    BUG(("%%%%Unsupported protocol.\n"));
	    longjmp(parse_env, ISC_LOGOUT);
	}
    }

    switch(client->protocol)
    {
    case 'A':
	prot_a_parse_packet(client);
	break;

    default:
	restart_kom("parse_packet(): Bad protocol.\n");
	break;
    }
}

/*
 * Free all parsed areas which are no longer needed. Re-initialize all
 * parse_pos fields so that the parse will expect a new function.
 *
 * This function is called
 *	when a parse error occurs
 *	when a parse is complete and the function has executed.
 */
static void
free_parsed(Connection *client)
{
    s_clear(&client->c_string0);
    s_clear(&client->c_string1);
    client->string0 = EMPTY_STRING; /* So that no one frees it. */
    sfree( client->c_misc_info_p);
    client->c_misc_info_p = NULL;
    sfree( client->c_local_text_no_p);
    client->c_local_text_no_p = NULL;
    client->parse_pos = 0;
    client->fnc_parse_pos = 0;
    client->array_parse_pos = 0;
    client->struct_parse_pos = 0;
    client->string_parse_pos = 0;
}

/*
 * Send a reply to a call.
 */
static void
reply(Connection *client,
      Success	      status,
      Result_holder  *result)
{
    switch(client->protocol)
    {
    case 'A':
	prot_a_reply(client, status, result);
	break;

    default:
	restart_kom("reply(): Bad protocol.\n");
	break;
    }
}


/*
 * Try to parse enough data from client->unparsed to call a function.
 * If more data is needed set client->more_to_parse to FALSE.
 */
static void
parse_unparsed(Connection *client)
{
    String        tmp_str = EMPTY_STRING;
    Success       status;
    Result_holder result;
        
    switch ( setjmp(parse_env) )
    {
    case 0 :
	/* Parse message. If message is complete call function and reply. */
	parse_packet(client);
	client->last_request = time(NULL);
	status = call_function(client, &result);
	reply(client, status, &result);
	free_parsed(client);
	end_of_atomic(FALSE);
	break;

    case ISC_PROTOCOL_ERR:
	s_clear(&client->string0);
	free_parsed(client);
	mux_printf(client, "%% LysKOM protocol error.\n");
	mux_flush(client);
	BUG(("%%%% Protocol error.\n"));
	s_clear(&client->unparsed);
	client->first_to_parse = 0;
	client->more_to_parse = FALSE;
	end_of_atomic(FALSE);
	break;

    case ISC_MSG_INCOMPLETE:
	client->more_to_parse = FALSE;
	break;

    case ISC_LOGOUT:
	add_to_kill_list(client);
	break;
    }
    
    /* Delete the parsed part of 'unparsed' */
    
    if ( s_substr(&tmp_str, client->unparsed,
		  client->first_to_parse, END_OF_STRING) != OK )
	restart_kom("parse_unparsed: s_substr\n");

    s_clear(&client->unparsed);
    client->unparsed = tmp_str;
    client->first_to_parse = 0;
}


/*
 * There is a message in the event. Parse it.
 */
static void
parse_message(Connection *cp, String tmp_str)
{
    VBUGSTR(tmp_str);

    cp->more_to_parse = TRUE;
    
    if ( s_strcat(&cp->unparsed, tmp_str) != OK )
	restart_kom("parse_message(): s_strcat\n");

    tmp_str = EMPTY_STRING;
    
    /* Parse this packet, but leave the last token if it isn't complete. */

    parse_unparsed(cp);

    return;
}

static void
mux_handle_packet(Mux *mux)
{
    Mux_client *mcp = NULL;
    Connection *cp = NULL;

    switch(mux->parse.function)
    {
    case 0:			/* ping */
	isc_printf(mux->scb, "0\n");
	isc_flush(mux->scb);
	break;

    case 1:			/* login */

	mcp = mux_getclientbyid(mux, mux->parse.num);
	if (mcp)
	{			/* ERROR %d: Already logged in\n */
	    isc_printf(mux->scb, "4\n");
	    isc_flush(mux->scb);
	    return;
	}
    
	cp = new_client();
	cp->mux = mux;
	cp->hostname = mux->parse.string;
	mux->parse.string = EMPTY_STRING;
	
	mux_addclient(mux, mux->parse.num, cp);

    
	BUG(("\n[Client %d from %.*s via MUX %s",
	     cp->session_no,
	     (int)cp->hostname.len,
	     cp->hostname.string,
	     isc_gethostname(mux->scb->info.tcp.raddr, NULL, 0)));
	BUG((" is connecting]\n"));

	break;
    
    case 2:			/* logout */
	mcp = mux_getclientbyid(mux, mux->parse.num);
	if (!mcp)
	{			/* ERROR %d: No such mux-session */
	    isc_printf(mux->scb, "4\n");
	    isc_flush(mux->scb);
	    return;
	}

	cp = mcp->conn;
    
	BUG(("\n[Client %d via MUX(%s)",
	     cp->session_no,
	     isc_gethostname(mux->scb->info.tcp.raddr, NULL, 0)));
	BUG((" is logging out by request]\n"));

	add_to_kill_list(cp);
	break;

    case 3:			/* msg */
	mcp = mux_getclientbyid(mux, mux->parse.num);
	if (!mcp)
	{			/* ERROR %d: No such mux-session */
	    isc_printf(mux->scb, "4\n");
	    isc_flush(mux->scb);
	    return;
	}
    
	cp = mcp->conn;
    
	VBUG(("\n[Message client %d via MUX #%d]\n",
	      cp->session_no, (int)mux->scb));

	parse_message(cp, mux->parse.string);
	break;

    default:
	
	VBUG(("\nMUX Protocol error from MUX #%d]\n",
	      (int)mux->scb));

	isc_printf(mux->scb, "5\n");
	isc_flush(mux->scb);
	break;
	
    }
}
	
static void
mux_logout(Mux *mp)
{
    int i;

    for (i = 0; i < mp->client_c; i++)
	if (mp->client_v[i].conn)
	{
	    BUG(("\n[Client %d via MUX(%s)",
		 mp->client_v[i].conn->session_no,
		 isc_gethostname(mp->scb->info.tcp.raddr, NULL, 0)));
	    BUG((" is logging out by MUX shutdown]\n"));
	    logout_client(mp->client_v[i].conn);
	    end_of_atomic(FALSE);
	}
	      
    isc_destroy(kom_server_mcb, mp->scb);
    mux_destruct(mp);
}


static void
mux_parse_unparsed(Mux *mux)
{
    String        tmp_str;

    while ( mux->parse.more_to_parse )
    {
	switch ( setjmp(mux_parse_env) )
	{
	case 0 :
	    /* Parse message. Take apropriate action if message is complete. */
	    mux_parse_packet(mux);
	    mux_handle_packet(mux);
	    mux_free_parsed(mux);
	    break;

	case MUX_PROTOCOL_ERR:
	    s_clear(&mux->parse.string);
	    mux_free_parsed(mux);
	    isc_printf(mux->scb, "5\n");
	    isc_flush(mux->scb);
	    BUG(("%%%% Mux protocol error.\n"));
	    s_clear(&mux->parse.unparsed);
	    mux->parse.first_to_parse = 0;
	    mux->parse.more_to_parse = FALSE;
	    break;

	case MUX_MSG_INCOMPLETE:
	    mux->parse.more_to_parse = FALSE;
	    break;

	case MUX_LOGOUT:
	    mux_logout(mux);
	    return;
	}
    
	/* Delete the parsed part of 'unparsed' */

	tmp_str = EMPTY_STRING;

	if ( s_substr(&tmp_str, mux->parse.unparsed,
		      mux->parse.first_to_parse, END_OF_STRING) != OK )
	    restart_kom("mux_parse_unparsed: s_substr\n");

	s_clear(&mux->parse.unparsed);
	mux->parse.unparsed = tmp_str;
	mux->parse.first_to_parse = 0;
    }
}


static void
mux_parse_message(Mux *mp, String tmp_str)
{
    VBUGSTR(tmp_str);

    BUG(("mux_parse_message(): mp->parse.unparsed = { len = %d, "
	 "string = %p }\n", mp->parse.unparsed.len,
	 (void *)mp->parse.unparsed.string));
    
    if ( s_strcat(&mp->parse.unparsed, tmp_str) != OK )
	restart_kom("mux_parse_message(): s_strcat\n");

    tmp_str = EMPTY_STRING;
    
    /* Parse this packet, but leave the last token if it isn't complete. */

    mux_parse_unparsed(mp);

    return;
}

/*
 * parse data in client->unparsed and mux->unparsed if there
 * is data that has not yet been taken care of. Return TRUE
 * if there was no data to take care of.
 */
static Bool
parse_forgotten(void)
{
    Bool flg = FALSE;			/* Was there anything? */
    Connection *ci;
    Session_no session_no = 0;

    if ( traverse_connections(0) == 0 )
	return TRUE;

    while ( ( session_no = traverse_connections( session_no ) ) != 0 )
    {
	ci = get_conn_by_number (session_no);

	if ( ci->more_to_parse )
	{
	    parse_unparsed(ci);
	    flg = TRUE;
	}
    }

    return !flg;
}


/* Return 1 if the named file exists, 0 otherwise */
static int
fexists(const char *filename)
{
    struct stat buf;
    int code;
  
    code = !stat(filename, &buf);
    errno = 0;

    return code;
}


void
dump_statistics(void)
{
    static time_t last_dump = NO_TIME;
    int i;
    time_t now;
    FILE *fp;
    extern char statisticfile[1024]; /* Defined in ramkomd.c */

    if ( (fp = fopen(statisticfile, "a")) == NULL )
    {
	log(__FILE__ ": dump_statistics(): can't open file %s\n",
	    statisticfile);
	return;
    }

    time(&now);

    if (last_dump == NO_TIME)
    {
	fprintf(fp, "RESTART\n");
	last_dump = now;
    }
    
    fprintf(fp, "TIME: %s", ctime(&now));
    fprintf(fp, "SECONDS: %d\n", (int)difftime(now, last_dump));
    fprintf(fp, "STATISTICS:");
    for ( i = 0; i < sizeof(service_statistics) / sizeof(u_long); i++)
    {
	fprintf(fp, " %lu", service_statistics[i]);
	service_statistics[i]=0;
    }

    fprintf(fp, "\n");
    fclose(fp);

    last_dump = now;
}

/* List of connections to kill. */

Session_no *kill_list = NULL;
int kill_list_size = 0;

/* Schedule this client for termination. */
void
add_to_kill_list(Connection *conn)
{
    int i;

    for (i = 0; i < kill_list_size; i++)
	if (kill_list[kill_list_size] == conn->session_no)
	{
	    log("add_to_kill_list(%d): already present as %d of %d.\n",
		conn->session_no, i, kill_list_size);
	    return;
	}

    if (kill_list == NULL)
    {
	if (kill_list_size != 0)
	    restart_kom("add_to_kill_list(): size = %d\n", kill_list_size);

	kill_list_size = 1;
	kill_list = smalloc(sizeof(Session_no));
    }
    else
    {
	kill_list_size++;
	kill_list = srealloc(kill_list, kill_list_size * sizeof(Session_no));
    }

    kill_list[kill_list_size-1] = conn->session_no;
}

/*
 * check_kill_flg must NEVER be called inside an atomic call!
 */
static void
check_kill_flg(void)
{
    Connection *conn;

    if ( active_connection != NULL )
    {
	restart_kom("check_kill_flg: active_connection == %d",
		    active_connection->session_no);
    }

    while (kill_list_size > 0)
    {
	--kill_list_size;
	conn = get_conn_by_number (kill_list[kill_list_size]);
	if (conn == NULL)
	{
	    log("check_kill_flg(): Connection %d doesn't exist.\n",
		kill_list[kill_list_size]);
	}
	else
	{
	    logout_client (conn);
	    end_of_atomic (FALSE);
	}
    }

    if (kill_list != NULL)
    {
	sfree (kill_list);
	kill_list = NULL;
    }
}

static void
login_request(IscEvent  *event)
{
    Connection  * cp;
    char *realuser;
    int localport;
    IscAddress *isc_adr;
    char *hostname = NULL;

    if (isc_sessions(kom_server_mcb) >= MAX_NO_OF_CONNECTIONS)
    {
	BUG(("Connection attempt rejected.\n"));
	isc_printf(event->session, "%s", "%% No connections left.\n");
	isc_flush(event->session);
	isc_destroy(kom_server_mcb, event->session);
	      
	async_rejected_connection();
	return;
    }

    /* Supress logins if /etc/nologin exists */
    if (fexists("/etc/nologin"))
    {
	isc_printf(event->session, "%s", "%% No logins allowed.\n");
	isc_flush(event->session);
 	isc_destroy(kom_server_mcb, event->session);
	return;
    }

    /* Find out if it is a mux or a client that tries to connect to
       us.  Do it by getting the local port number. */

    isc_adr = isc_getladdress (event->session);
    if (isc_adr == NULL)
	restart_kom("login_request(): can't isc_getladdress (%lu)\n",
		    event->session);

    localport = isc_getportnum (isc_adr);
    isc_freeaddress (isc_adr);
    
    if (localport == num_ip_mux_port)
    {
	/* Multiplexer requesting connection */

	/*
	 ** Create, and setup the MUX for the MUX case
	 */
	event->session->udg = mux_create(MUX_TYPE_MUX, event->session);
	      
	BUG(("MUX #%d at %s connecting.\n",
	     (int)event->session,
	     isc_gethostname(event->session->info.tcp.raddr, NULL, 0)));
    }
    else if (localport == num_ip_client_port)
    {
	/* Client requesting connection */
	      
	/*
	 ** Create, and setup the MUX for the CLIENT case
	 */
	event->session->udg = mux_create(MUX_TYPE_CLIENT,
					 event->session);
	      
	cp = new_client();
	cp->mux = event->session->udg;
	hostname = isc_gethostname(event->session->info.tcp.raddr, NULL, 0);
	if (hostname == NULL)
	    hostname = isc_getipnum(event->session->info.tcp.raddr, NULL, 0);
	if (hostname == NULL)
	{
	    log("WNG: login_request(): unknown hostid.\n");
	    s_crea_str(&cp->hostname, "unknown");
	}
	else
	    s_crea_str(&cp->hostname, hostname);

	/* Get the real user name, as returned by the Ident protocol
	   (rfc 931). */
	realuser = get_real_username(event->session);
	if (realuser != NULL)
	    s_crea_str(&cp->ident_user, realuser);

	mux_addclient(event->session->udg, 0, cp);
	      
	BUG(("\n[Client %d from %s", cp->session_no,
	     isc_gethostname(event->session->info.tcp.raddr, NULL, 0)));
	BUG((" is connecting]\n"));
    }
    else
    {
	/* Help! It was neither a client, nor a mux. */
	restart_kom("login_request(): Neither client, nor mux.\n");
    }
}

static void
logout_request(IscEvent *event)
{
    Connection  * cp;
    
    if (event->session->udg->type == MUX_TYPE_MUX)
    {
	BUG(("\n[MUX #%d at %s", (int)event->session,
	     isc_gethostname(event->session->info.tcp.raddr, NULL, 0)));
	BUG((" is logging out]\n"));

	/*
	 ** Logout any remaining clients
	 */
	mux_logout(event->session->udg);
    }
    else
    {
	cp = event->session->udg->client_v[0].conn;
	      
	BUG(("\n[Client %d from %s", cp->session_no,
	     isc_gethostname(event->session->info.tcp.raddr, NULL, 0)));
	BUG((" is logging out]\n"));
	      
	add_to_kill_list(cp);
    }
}


static void
message_request(IscEvent *event)
{
    Connection *cp;
    String      tmp_str;

    if (event->session->udg->type == MUX_TYPE_MUX)
    {
	event->session->udg->parse.more_to_parse = TRUE;
	tmp_str.string = (unsigned char *)event->msg->buffer;
	tmp_str.len    = event->msg->length;
	mux_parse_message(event->session->udg, tmp_str);
    }
    else
    {
	cp = event->session->udg->client_v[0].conn;
	VBUG(("\n[Message from client %d]\n",
	      cp->session_no));
	/*
	 ** Pass the message on to the parser
	 */
	tmp_str.string = (unsigned char *)event->msg->buffer;
	tmp_str.len    = event->msg->length;
	parse_message(cp, tmp_str);
    }
}

static long
timevaldiff(struct timeval a,
	    struct timeval b)
{
    return 1000000 * (a.tv_sec - b.tv_sec) + a.tv_usec - b.tv_usec;
}

void
toploop(void)
{
    IscEvent      * event;
    Bool	pending_input = TRUE; /* Should be TRUE whenever there
				         is or might be pending input
					 from any client in the unparsed
					 buffer. */
    long	timeout = 0;        /* In milliseconds. Start with a
				       small value since we should
				       start garbing right away. */
    struct timeval before, after;
    
    while ( !go_and_die )
    {
        if (do_sync_db)
	{
	    /*
	     * do_sync_db used to save the entire database. Nowadays
	     * all it does is to print some statistics.
	     */
	    cache_sync();	/* A noop in lyskomd. Actually
				   stops the server and dumps
				   everything in ramkomd. */
	    dump_statistics();
	    do_sync_db = FALSE;
	}

	gettimeofday(&before, NULL);
	event = isc_getnextevent(kom_server_mcb,
				 pending_input ? 0 : timeout );
	gettimeofday(&after, NULL);

	timeout -= timevaldiff(after, before) / 1000;

	if ( timeout < 0 )
	    timeout = 0;
	
	if ( event == NULL )
	    restart_kom("toploop(): Got NULL event - shouldn't happen...\n");

	switch ( event->event )
	{
	case ISC_EVENT_ERROR:
	    if (errno != EINTR)
	    {
		log("toploop: ISC_EVENT_ERROR (error = '%s'):\n   '%s'\n",
		    strerror(errno), event->msg ? event->msg->buffer
		    : "(unknown)");
	    }
	    break;
	    
	case ISC_EVENT_TIMEOUT:
	    BUG((">"));
#ifdef DEBUG
	    fflush(stdout);
#endif
	    if ( pending_input == FALSE )
		timeout = end_of_atomic(TRUE); /* Idle. Do some cleaning up. */
	    else
	    {
		if ( timeout == 0 )
		    end_of_atomic(FALSE);
		pending_input = !parse_forgotten();
	    }
	    
	    	    
	    break;
	    
	case ISC_EVENT_LOGIN:
	    pending_input = TRUE;
	    login_request(event);
	    break;

	case ISC_EVENT_LOGOUT:
	    pending_input = TRUE;
	    logout_request(event);
	    break;

 	case ISC_EVENT_MESSAGE:
	    pending_input = TRUE;
	    message_request(event);
	    break;

	default:
	    pending_input = TRUE;
	    log("ERROR: toploop(): Unknown ISC_EVENT\n");
	    break;
	}

        isc_dispose(event);

	check_kill_flg();
    }
}