mux-parse.c 4.79 KB
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/*
 ** mux-parse.c                                    Handle the MUX protocol
 * This is a hack. Clean this mess up with lacgen.
 */
 
#include <stddef.h>
#include <stdarg.h>
#include <string.h>
#include "lyskomd.h"
#include <kom-types.h>
#include "com.h"
#include "connections.h"
#include "isc.h"
#include "mux.h"
#include "smalloc.h"
#include <setjmp.h>
#include <string.h>
#include <stdio.h>
#include "mux-parse.h"
#include "minmax.h"
#include "config.h"
#include <s-string.h>

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,
		      s_fcrea_str(" \t\n\r"));

    /* 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
 * are read. The following characters are discarded.
 */
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;
    String tmp;

    switch ( mux->parse.string_parse_pos )
    {
    case 0:
	/* Get number and discard trailing 'H' */
	result->len = s_strtol(s_fsubstr(mux->parse.unparsed,
					 mux->parse.first_to_parse,
					 END_OF_STRING),
			       &hptr, PROTOCOL_NUMBER_BASE);

	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 */

	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;
	/* Fall through */
    case 1:
	/* 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) */
	truncated_len = min(maxlen + 1, result->len);
	mux_len = result->len;
	
	if ( mux->parse.first_to_parse + truncated_len
	    > s_strlen(mux->parse.unparsed) )
	{
	    longjmp(mux_parse_env, MUX_MSG_INCOMPLETE);
	}

	result->string = (mux->parse.unparsed.string
			  + mux->parse.first_to_parse);
	result->len = truncated_len;
	tmp = EMPTY_STRING;
	s_strcpy(&tmp, *result); /* Copy the string. */
	*result = tmp;
	result->len = mux_len;

	mux->parse.first_to_parse += truncated_len;
	mux->parse.string_parse_pos = 2;
	/* Fall through */
    case 2:
	/* Was the string too long? If so, skip the truncated data. */

	mux_len = result->len;
	truncated_len = min(maxlen+1, result->len);
	
	if ( mux_len > truncated_len )
	{
	    to_skip = min(mux_len - truncated_len,
			   mux->parse.unparsed.len - mux->parse.first_to_parse);
	    mux_len -= to_skip;
	    mux->parse.first_to_parse += to_skip;
	}

	result->len = mux_len;
	
	if ( mux_len > truncated_len )
	    longjmp(mux_parse_env, MUX_MSG_INCOMPLETE);
	/* 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;
    }
}