zmodem.c

Gcomm is a serial communications program similar to seyon, but more modern, and easier to use. Works

#ifndef lint
static const char rcsid[] = "$Id: zmodem.c,v 1.1.1.1 2001/03/08 00:01:48 efalk Exp $" ;
#endif

/*
 * Copyright (c) 1995 by Edward A. Falk
 */


/**********
 *
 *
 *	@@@@@  @   @   @@@   @@@@   @@@@@  @   @  
 *	   @   @@ @@  @   @  @   @  @      @@ @@  
 *	  @    @ @ @  @   @  @   @  @@@    @ @ @  
 *	 @     @ @ @  @   @  @   @  @      @ @ @  
 *	@@@@@  @ @ @   @@@   @@@@   @@@@@  @ @ @  
 *
 *	ZMODEM - main logic parser for zmodem library
 *
 *
 *	Routines provided here:
 *
 *
 *	name (args)
 *		Brief description.
 *
 *	int ZmodemRcv(u_char *buffer, int len, ZModem *info)
 *		Call whenever characters are received.  If this function
 *		returns ZmDone, previous function has completed successfully,
 *		either call ZmodemTFile() to start next file, or call
 *		ZmodemTFinish() to terminate the session.
 *
 *
 *	int
 *	ZmodemTimeout(ZModem *info)
 *		Call whenever the timeout period expires and no
 *		characters have been received.
 *
 *	int
 *	ZmodemAttention(ZModem *info)
 *		Call whenever the attention sequence has been received
 *		from the remote end.  It is safe to call this function
 *		from an interrupt handler.
 *
 *	int
 *	ZmodemAbort(ZModem *info)
 *		Call to abort transfer.  Physical connection remains
 *		open until you close it.
 *
 *
 *
 *
 *	Edward A. Falk
 *
 *	January, 1995
 *
 *
 *
 **********/

#include <stdio.h>

/****
 *
 * Constants,  typedefs, externals, globals, statics, macros, block data
 *
 ****/



/* TODO: sample input before initial send */
/* TODO: more intelligent timeout dispatch */
/* TODO: read all pending input before sending next data packet out */
/* TODO: if received ZDATA while waiting for ZFILE/ZFIN, it's probably
	leftovers */
/* TODO: enable flow control for zmodem, disable for X/YModem */

#include <ctype.h>
#include <errno.h>
#include <string.h>

#include "zmodem.h"
#include "crctab.h"

static	u_char	zeros[4] = {0,0,0,0} ;


extern	int	YrcvChar( char c, register ZModem *info ) ;
extern	int	YrcvTimeout( register ZModem *info ) ;
extern	void	ZIdleStr(u_char *buffer, int len, ZModem *info) ;


	/* LEXICAL BOX: handle characters received from remote end.
	 * These may be header, data or noise.
	 *
	 * This section is a finite state machine for parsing headers
	 * and reading input data.  The info->chrCount field is effectively
	 * the state variable.
	 */

static	int	FinishChar( char c, register ZModem *info ) ;
static	int	DataChar( u_char c, register ZModem *info ) ;
static	int	HdrChar( u_char c, register ZModem *info ) ;
static	int	IdleChar(u_char c, register ZModem *info) ;
extern	int	YsendChar() ;

static	int	ZProtocol(), ZDataReceived() ;


int
ZmodemRcv( register u_char *str, int len, register ZModem *info )
{
register u_char	c ;
	int	err ;

	info->rcvlen = len ;

	while( --info->rcvlen >= 0 )
	{
	  c = *str++ ;

	  if( c == CAN ) {
	    if( ++info->canCount >= 5 ) {
	      ZStatus(RmtCancel, 0, NULL) ;
	      return ZmErrCancel ;
	    }
	  }
	  else
	    info->canCount = 0 ;

	  if( info->InputState == Ysend ) {
	    if( (err = YsendChar(c, info)) )
	      return err ;
	  }
	  else if( info->InputState == Yrcv ) {
	    if( (err = YrcvChar(c, info)) )
	      return err ;
	  }

	  else if( c != XON && c != XOFF )
	  {
	    /* now look at what we have */

	    switch( info->InputState )
	    {
	      case Idle:
		if( (err = IdleChar(c, info)) )
		  return err ;
		break ;

	      case Inhdr:
		if( (err = HdrChar(c, info)) )
		  return err ;
		break ;

	      case Indata:
		if( (err = DataChar(c, info)) )
		  return err ;
		break ;

	      case Finish:
		if( (err = FinishChar(c, info)) )
		  return err ;
		break ;

	      default:
		break ;
	    }
	  }
	}

	return 0 ;
}







	/* handle character input while idling
	 * looking for ZPAD-ZDLE sequence which introduces a header
	 */

static	int
IdleChar(u_char c, register ZModem *info)
{
	if( info->chrCount == 0 )
	{
	  if( c == ZPAD )
	    ++info->chrCount ;
	  else if( info->state == Sending  &&  ++info->noiseCount > MaxNoise )
	    info->waitflag = 1 ;
	  else if( info->state == TStart && (c == 'C' || c == 'G' || c == NAK) )
	  {
	    /* switch to ymodem */
	    info->state = YTStart ;
	    info->InputState = Ysend ;
	    info->Protocol = YMODEM ;
	    return YsendChar(c, info) ;
	  }
	  else
	    ZIdleStr(&c, 1, info) ;
	}

	else
	{
	  switch( c ) {
	    case ZPAD:
	      ++info->chrCount ;
	      break ;
	    case ZDLE:
	      info->InputState = Inhdr ;
	      info->chrCount=0 ;
	      break ;
	    default:
	      while( --info->chrCount >= 0 )
		ZIdleStr((u_char *)"*", 1, info) ;
	      info->chrCount = 0 ;
	      break ;
	  }
	}
	return 0 ;
}



static	u_int
rcvHex( u_int i, char c )
{
	if( c <= '9' )
	  c -= '0' ;
	else if( c <= 'F' )
	  c -= 'A'-10 ;
	else
	  c -= 'a'-10 ;
	return (i<<4)+c ;
}

	/* handle character input in a header */

static	int
HdrChar( u_char c, register ZModem *info )
{
	int	i ;
	int	crc=0 ;

	if( c == ZDLE ) {
	  info->escape = 1 ;
	  return 0 ;
	}

	if( info->escape ) {
	  info->escape = 0 ;
	  switch( c ) {
	    case ZRUB0: c = 0177 ; break ;
	    case ZRUB1: c = 0377 ; break ;
	    default: c ^= 0100 ; break ;
	  }
	}

	if( info->chrCount == 0 ) {	/* waiting for format */
	  switch( c ) {
	    case ZHEX:
	    case ZBIN:
	    case ZBIN32:
	      info->DataType = c ;
	      info->chrCount = 1 ;
	      info->crc = (info->DataType != ZBIN32) ? 0 : 0xffffffffL ;
	      memset(info->hdrData,0,sizeof(info->hdrData)) ;
	      break ;
	    default:
	      info->InputState = Idle ;
	      info->chrCount = 0 ;
	      return ZXmitHdrHex(ZNAK, zeros, info) ;
	  }
	  return 0 ;
	}


	switch( info->DataType ) {
	  /* hex header is 14 hex digits, cr, lf.  Optional xon is ignored */
	  case ZHEX:
	    if( info->chrCount <= 14  &&   !isxdigit(c) ) {
		info->InputState = Idle ;
		info->chrCount = 0 ;
		return ZXmitHdrHex(ZNAK, zeros, info) ;
	    }

	    if( info->chrCount <= 14 ) {
	      i = (info->chrCount-1)/2 ;
	      info->hdrData[i] = rcvHex(info->hdrData[i], c) ;
	    }

	    if( info->chrCount == 16 ) {
	      crc = 0 ;
	      for(i=0; i<7; ++i)
		crc = updcrc(info->hdrData[i], crc) ;
	      info->InputState = Idle ;
	      info->chrCount = 0 ;
	      if( (crc&0xffff) != 0 )
		return ZXmitHdrHex(ZNAK, zeros, info) ;
	      else
		return ZProtocol(info) ;
	    }
	    else
	      ++info->chrCount ;
	    break ;


	  case ZBIN:
	    /* binary header is type, 4 bytes data, 2 bytes CRC */
	    info->hdrData[info->chrCount-1] = c ;
	    info->crc = updcrc(c, info->crc) ;
	    if( ++info->chrCount > 7 ) {
	      info->InputState = Idle ;
	      info->chrCount = 0 ;
	      if( (crc&0xffff) != 0 )
		return ZXmitHdrHex(ZNAK, zeros, info) ;
	      else
		return ZProtocol(info) ;
	    }
	    break ;


	  case ZBIN32:
	    /* binary32 header is type, 4 bytes data, 4 bytes CRC */
	    info->hdrData[info->chrCount-1] = c ;
	    info->crc = UPDC32(c, info->crc) ;
	    if( ++info->chrCount > 9 ) {
	      info->InputState = Idle ;
	      info->chrCount = 0 ;
	      if( info->crc != 0xdebb20e3 )	/* see note below */
		return ZXmitHdrHex(ZNAK, zeros, info) ;
	      else
		return ZProtocol(info) ;
	    }
	    break ;
	}
	return 0 ;
}

	/* handle character input in a data buffer */

static	int
DataChar( u_char c, register ZModem *info )
{
	if( c == ZDLE ) {
	  info->escape = 1 ;
	  return 0 ;
	}

	if( info->escape ) {
	  info->escape = 0 ;
	  switch( c ) {
	    case ZCRCE:
	    case ZCRCG:
	    case ZCRCQ:
	    case ZCRCW:
	      info->PacketType = c ;
	      info->crcCount = (info->DataType == ZBIN32) ? 4 : 2 ;
		if( info->DataType == ZBIN )
		  info->crc = updcrc(c, info->crc) ;
		else
		  info->crc = UPDC32(c, info->crc) ;
	      return 0 ;
	    case ZRUB0: c = 0177 ; break ;
	    case ZRUB1: c = 0377 ; break ;
	    default: c ^= 0100 ; break ;
	  }
	}


	switch( info->DataType ) {
	  /* TODO: are hex data packets ever used? */

	  case ZBIN:
	    info->crc = updcrc(c, info->crc) ;
	    if( info->crcCount == 0 )
	      info->buffer[info->chrCount++] = c ;
	    else if( --info->crcCount == 0 ) {
	      return ZDataReceived(info, (info->crc&0xffff) == 0) ;
	    }
	    break ;


	  case ZBIN32:
	    info->crc = UPDC32(c, info->crc) ;
	    if( info->crcCount == 0 )
	      info->buffer[info->chrCount++] = c ;
	    else if( --info->crcCount == 0 ) {
	      return ZDataReceived(info, info->crc == 0xdebb20e3) ;
	    }
	    break ;
	}
	return 0 ;
}


	/* wait for "OO" */

static	int
FinishChar( char c, register ZModem *info )
{
	if( c == 'O' ) {
	  if( ++info->chrCount >= 2 )
	    return ZmDone ;
	}
	else
	  info->chrCount = 0 ;
	return 0 ;
}






	int	ZPF() ;
	int	Ignore() ;
	int	AnswerChallenge() ;
	int	GotAbort() ;
	int	GotCancel() ;
	int	GotCommand() ;
	int	GotStderr() ;
	int	RetDone() ;
static	int	GotCommandData() ;
static	int	GotStderrData() ;

	/* PROTOCOL LOGIC:  This section of code handles the actual
	 * protocol.  This is also driven by a finite state machine
	 *
	 * State tables are sorted by approximate frequency order to
	 * reduce search time.
	 */

	/* Extra ZRINIT headers are the receiver trying to resync.  */



	/* If compiling for Send Only or Receive Only, convert table
	 * entries to no-ops so we don't have to link zmodem[rt].o
	 */

#if	SendOnly
#define	RStartOps	DoneOps
#define	RSinitWaitOps	DoneOps
#define	RFileNameOps	DoneOps
#define	RCrcOps		DoneOps
#define	RFileOps	DoneOps