mux-parse.c 6.83 KB
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/*
 * $Id: mux-parse.c,v 0.7 1991/09/15 10:30:54 linus 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. 
 */
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/*
 ** mux-parse.c                                    Handle the MUX protocol
 * This is a hack. Clean this mess up with lacgen.
 */
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static char *rcsid = "$Id: mux-parse.c,v 0.7 1991/09/15 10:30:54 linus Exp $";
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#include <stddef.h>
#include <stdarg.h>
#include <string.h>
#include "lyskomd.h"
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#include "s-string.h"
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#include <kom-types.h>
#include "com.h"
#include "connections.h"
#include "isc.h"
#include "mux.h"
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#include <server/smalloc.h>
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#include <setjmp.h>
#include <string.h>
#include <stdio.h>
#include "mux-parse.h"
#include "minmax.h"
#include "config.h"
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#include "log.h"
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jmp_buf mux_parse_env;

static String
mux_get_token(Mux *mux)
{
    String result;
    String_size old_first;

    old_first = mux->parse.first_to_parse;
    
    result = s_strtok(mux->parse.unparsed, &mux->parse.first_to_parse,
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		      s_fcrea_str(WHITESPACE));
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    /* Check that there was at least one trailing blank. */
    
    if ( mux->parse.first_to_parse >= s_strlen(mux->parse.unparsed) )
    {
	mux->parse.first_to_parse = old_first;
	longjmp(mux_parse_env, MUX_MSG_INCOMPLETE);
    }

    return result;
}

static long
mux_parse_long(Mux *mux)
{
    String	token;
    String_size end;
    long	res;

    token = mux_get_token(mux);
    res = s_strtol(token, &end, PROTOCOL_NUMBER_BASE);
    if (end != s_strlen(token))
	longjmp(mux_parse_env, MUX_PROTOCOL_ERR);
    
    return res;
}


/*
 * Parse a string. At most 'maxlen' characters are allowed. If the
 * mux sends a longer string only the first 'maxlen+1' characters
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 * are read. Any remaining characters are discarded.
 *
 * longjmp if not enough characters are available or if there
 * is an error. Result is used to save state in that case.
 * +++ Result should not be used to save state.
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 */
static void
mux_parse_string(Mux	    *mux,
		 String	    *result,
		 int	     maxlen)
{
    String_size hptr;		/* Pointer to 'H' */
    String_size mux_len;	/* The len the mux is sending. */
    String_size truncated_len;	/* How much the server will receive. */
    String_size to_skip;
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    static u_long err_cnt = 0;
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    switch ( mux->parse.string_parse_pos )
    {
    case 0:
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	if ( ( result->len != 0 || result->string != NULL) && err_cnt++ < 20 )
	{
	    log ("mux_parse_string(): result->len == %lu, "
		 "result->string == %lu. This memory will not be free()'d.\n",
		 (u_long)result->len, (u_long)result->string);
	    *result = EMPTY_STRING;
	    if ( err_cnt == 20 )
		log("Won't log the above warning no more.");
	}
	
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	/* Get number and discard trailing 'H' */
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	mux_len = s_strtol(s_fsubstr(mux->parse.unparsed,
				     mux->parse.first_to_parse,
				     END_OF_STRING),
			   &hptr, PROTOCOL_NUMBER_BASE);
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	if ( hptr == -1
	    || mux->parse.first_to_parse + hptr
	    >= s_strlen(mux->parse.unparsed) )
	{
	    longjmp(mux_parse_env, MUX_MSG_INCOMPLETE);
	}
	
	/* Check that
	      a) there is a trailing H
	      b) there was at least one digit before the H */

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	/* +++ Use s-string.c to extract the char. */
	/* +++ Fix prot_a_parse_string also. */
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	if ( mux->parse.unparsed.string[ mux->parse.first_to_parse
					  + hptr ] != 'H'
	    || hptr <= 0 )
	{
	    longjmp(mux_parse_env, MUX_PROTOCOL_ERR);
	}

	mux->parse.first_to_parse += 1 + hptr;
	mux->parse.string_parse_pos = 1;
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	result->len = mux_len;	/* +++ Transfer mux_len. */
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	/* Fall through */
    case 1:
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	mux_len = result->len;
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	/* Check that the entire string is transmitted. */
	/* (Don't care about the trailing part that will be skipped if the
	 *  string is longer than maxlen) */
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	truncated_len = min(maxlen + 1, mux_len);
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	if ( mux->parse.first_to_parse + truncated_len
	    > s_strlen(mux->parse.unparsed) )
	{
	    longjmp(mux_parse_env, MUX_MSG_INCOMPLETE);
	}

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	*result = EMPTY_STRING;

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	s_mem_crea_str(result,
		       mux->parse.unparsed.string + mux->parse.first_to_parse,
		       truncated_len);
	
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	mux->parse.first_to_parse += truncated_len;
	mux->parse.string_parse_pos = 2;
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	result->len = mux_len;	/* Can't transfer the local mux_len across
				 * call boundary. +++ There should be room
				 * for mux_len in the per-connection
				 * protocol data.
				 */
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	/* Fall through */
    case 2:
	/* Was the string too long? If so, skip the truncated data. */

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	mux_len = result->len;	/* +++ shouldn't modify ->len */
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	truncated_len = min(maxlen+1, mux_len);
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	if ( mux_len > truncated_len )
	{
	    to_skip = min(mux_len - truncated_len,
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			  mux->parse.unparsed.len - mux->parse.first_to_parse);
	    /* From now on, mux_len is length of result + numer of
	       chars to skip. Clean up this! +++
	     */
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	    mux_len -= to_skip;
	    mux->parse.first_to_parse += to_skip;
	}
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	result->len = mux_len;
	
	if ( mux_len > truncated_len )
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	{
	    /* +++ mux_len is transferred in result->len. */
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	    longjmp(mux_parse_env, MUX_MSG_INCOMPLETE);
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	}
	
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	/* Fall through */
    default:
	mux->parse.string_parse_pos = 0;
    }
}





static Bool
mux_is_legal_fnc(int fnc)
{
    switch(fnc)
    {
    case 0:
    case 1:
    case 2:
    case 3:
	return TRUE;

    default:
	return FALSE;
    }
}    

static void
mux_parse_client_message(Mux *mux)
{
    switch(mux->parse.parse_pos_2)
    {
    case 0:
	mux->parse.num = mux_parse_long(mux);
	mux->parse.parse_pos_2 = 1;
	/* Fall through */
    case 1:
	mux_parse_string(mux, &mux->parse.string, 10000);
	/* Fall through */
    default:
	mux->parse.parse_pos_2 = 0;
    }
}

void
mux_parse_packet(Mux *mux)
{
    switch(mux->parse.parse_pos)
    {
    case 0:			/* Get fnc_no */
	mux->parse.function = mux_parse_long(mux);
	if ( !mux_is_legal_fnc(mux->parse.function) )
	    longjmp(mux_parse_env, MUX_PROTOCOL_ERR);
	mux->parse.parse_pos = 1;
	/* Fall through */
    case 1:
	/* Call the function that parses the arguments for this call. */
	switch(mux->parse.function)
	{
	case 0:
	    break;

	case 2:
	    mux->parse.num = mux_parse_long(mux);
	    break;

	case 1:
	case 3:
	    mux_parse_client_message(mux);
	    break;
	}
	/* Fall through */
    default:
	mux->parse.parse_pos = 0;
    }
}