xmodemtransmit.c

This a naive implementation of BOOTP/TFTPBOOT, the protocols to use to bootstrap a computer through

/*
	Copyright 2001, 2002 Georges Menie (www.menie.org)

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU Lesser 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 Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser 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
*/

#include "baselib.h"
#include "xmodem.h"
#include "crc16.h"
#include "xmodemdefs.h"

int xmodemTransmit(unsigned char *src, int srcsz)
{
	unsigned char xbuff[1030]; /* 1024 for XModem 1k + 3 head chars + 2 crc + nul */
	int bufsz, crc = -1;
	unsigned char packetno = 1;
	int i, c, len = 0;
	int retry;

	for(;;) {
		for( retry = 0; retry < 16; ++retry) {
			if ((c = _inbyte((DLY_1S)<<1)) >= 0) {
				switch (c) {
				case 'C':
					crc = 1;
					goto start_trans;
				case NAK:
					crc = 0;
					goto start_trans;
				case CAN:
					if ((c = _inbyte(DLY_1S)) == CAN) {
						_outbyte(ACK);
						FLUSHINPUT;
						return -1; /* canceled by remote */
					}
					break;
				default:
					break;
				}
			}
		}
		_outbyte(CAN);
		_outbyte(CAN);
		_outbyte(CAN);
		FLUSHINPUT;
		return -2; /* no sync */

		for(;;) {
		start_trans:
			xbuff[0] = SOH; bufsz = 128;
			xbuff[1] = packetno;
			xbuff[2] = ~packetno;
			c = srcsz - len;
			if (c > bufsz) c = bufsz;
			if (c >= 0) {
				memset (&xbuff[3], 0, bufsz);
				if (c == 0) {
					xbuff[3] = CTRLZ;
				}
				else {
					memcpy (&xbuff[3], &src[len], c);
					if (c < bufsz) xbuff[3+c] = CTRLZ;
				}
				if (crc) {
					unsigned short ccrc = crc16_ccitt(&xbuff[3], bufsz);
					xbuff[bufsz+3] = (ccrc>>8) & 0xFF;
					xbuff[bufsz+4] = ccrc & 0xFF;
				}
				else {
					unsigned char ccks = 0;
					for (i = 3; i < bufsz+3; ++i) {
						ccks += xbuff[i];
					}
					xbuff[bufsz+3] = ccks;
				}
				for (retry = 0; retry < MAXRETRANS; ++retry) {
					for (i = 0; i < bufsz+4+(crc?1:0); ++i) {
						_outbyte(xbuff[i]);
					}
					if ((c = _inbyte(DLY_1S)) >= 0 ) {
						switch (c) {
						case ACK:
							++packetno;
							len += bufsz;
							goto start_trans;
						case CAN:
							if ((c = _inbyte(DLY_1S)) == CAN) {
								_outbyte(ACK);
								FLUSHINPUT;
								return -1; /* canceled by remote */
							}
							break;
						case NAK:
						default:
							break;
						}
					}
				}
				_outbyte(CAN);
				_outbyte(CAN);
				_outbyte(CAN);
				FLUSHINPUT;
				return -4; /* xmit error */
			}
			else {
				for (retry = 0; retry < 10; ++retry) {
					_outbyte(EOT);
					if ((c = _inbyte((DLY_1S)<<1)) == ACK) break;
				}
				FLUSHINPUT;
				return (c == ACK)?len:-5;
			}
		}
	}
}