commands/zmodem/zm.c
/*
 *   Z M . C
 *    ZMODEM protocol primitives
 *    05-09-88  Chuck Forsberg Omen Technology Inc
 *
 * Entry point Functions:
 *	zsbhdr(type, hdr) send binary header
 *	zshhdr(type, hdr) send hex header
 *	zgethdr(hdr, eflag) receive header - binary or hex
 *	zsdata(buf, len, frameend) send data
 *	zrdata(buf, len) receive data
 *	stohdr(pos) store position data in Txhdr
 *	long rclhdr(hdr) recover position offset from header
 */

#ifndef CANFDX
#include "zmodem.h"
#endif
int Rxtimeout = 100;		/* Tenths of seconds to wait for something */

#ifndef UNSL
#define UNSL
#endif


/* Globals used by ZMODEM functions */
int Rxframeind;		/* ZBIN ZBIN32, or ZHEX type of frame received */
int Rxtype;		/* Type of header received */
int Rxcount;		/* Count of data bytes received */
char Rxhdr[4];		/* Received header */
char Txhdr[4];		/* Transmitted header */
long Rxpos;		/* Received file position */
long Txpos;		/* Transmitted file position */
int Txfcs32;		/* TURE means send binary frames with 32 bit FCS */
int Crc32t;		/* Display flag indicating 32 bit CRC being sent */
int Crc32;		/* Display flag indicating 32 bit CRC being received */
int Znulls;		/* Number of nulls to send at beginning of ZDATA hdr */
char Attn[ZATTNLEN+1];	/* Attention string rx sends to tx on err */

static lastsent;	/* Last char we sent */
static Not8bit;		/* Seven bits seen on header */

static char *frametypes[] = {
	"Carrier Lost",		/* -3 */
	"TIMEOUT",		/* -2 */
	"ERROR",		/* -1 */
#define FTOFFSET 3
	"ZRQINIT",
	"ZRINIT",
	"ZSINIT",
	"ZACK",
	"ZFILE",
	"ZSKIP",
	"ZNAK",
	"ZABORT",
	"ZFIN",
	"ZRPOS",
	"ZDATA",
	"ZEOF",
	"ZFERR",
	"ZCRC",
	"ZCHALLENGE",
	"ZCOMPL",
	"ZCAN",
	"ZFREECNT",
	"ZCOMMAND",
	"ZSTDERR",
	"xxxxx"
#define FRTYPES 22	/* Total number of frame types in this array */
			/*  not including psuedo negative entries */
};

static char badcrc[] = "Bad CRC";

/* Send ZMODEM binary header hdr of type type */
void zsbhdr(type, hdr)
int type;
register char *hdr;
{
	register int n;
	register unsigned short crc;

	vfile("zsbhdr: %s %lx", frametypes[type+FTOFFSET], rclhdr(hdr));
	if (type == ZDATA)
		for (n = Znulls; --n >=0; )
			xsendline(0);

	xsendline(ZPAD); xsendline(ZDLE);

	if (Crc32t=Txfcs32)
		zsbh32(hdr, type);
	else {
		xsendline(ZBIN); zsendline(type); crc = updcrc(type, 0);

		for (n=4; --n >= 0; ++hdr) {
			zsendline(*hdr);
			crc = updcrc((0377& *hdr), crc);
		}
		crc = updcrc(0,updcrc(0,crc));
		zsendline(crc>>8);
		zsendline(crc);
	}
	if (type != ZDATA)
		flushmo();
}


/* Send ZMODEM binary header hdr of type type */
void zsbh32(hdr, type)
register char *hdr;
int type;
{
	register int n;
	register UNSL long crc;

	xsendline(ZBIN32);  zsendline(type);
	crc = 0xFFFFFFFFL; crc = UPDC32(type, crc);

	for (n=4; --n >= 0; ++hdr) {
		crc = UPDC32((0377 & *hdr), crc);
		zsendline(*hdr);
	}
	crc = ~crc;
	for (n=4; --n >= 0;) {
		zsendline((int)crc);
		crc >>= 8;
	}
}

/* Send ZMODEM HEX header hdr of type type */
void zshhdr(type, hdr)
int type;
register char *hdr;
{
	register int n;
	register unsigned short crc;

	vfile("zshhdr: %s %lx", frametypes[type+FTOFFSET], rclhdr(hdr));
	sendline(ZPAD); sendline(ZPAD); sendline(ZDLE); sendline(ZHEX);
	zputhex(type);
	Crc32t = 0;

	crc = updcrc(type, 0);
	for (n=4; --n >= 0; ++hdr) {
		zputhex(*hdr); crc = updcrc((0377 & *hdr), crc);
	}
	crc = updcrc(0,updcrc(0,crc));
	zputhex(crc>>8); zputhex(crc);

	/* Make it printable on remote machine */
	sendline(015); sendline(0212);
	/*
	 * Uncork the remote in case a fake XOFF has stopped data flow
	 */
	if (type != ZFIN && type != ZACK)
		sendline(021);
	flushmo();
}

/*
 * Send binary array buf of length length, with ending ZDLE sequence frameend
 */
static char *Zendnames[] = { "ZCRCE", "ZCRCG", "ZCRCQ", "ZCRCW"};

void zsdata(buf, length, frameend)
register char *buf;
int length;
int frameend;
{
	register unsigned short crc;

	vfile("zsdata: %d %s", length, Zendnames[(frameend-ZCRCE)&3]);
	if (Crc32t)
		zsda32(buf, length, frameend);
	else {
		crc = 0;
		for (;--length >= 0; ++buf) {
			zsendline(*buf); crc = updcrc((0377 & *buf), crc);
		}
		xsendline(ZDLE); xsendline(frameend);
		crc = updcrc(frameend, crc);

		crc = updcrc(0,updcrc(0,crc));
		zsendline(crc>>8); zsendline(crc);
	}
	if (frameend == ZCRCW) {
		xsendline(XON);  flushmo();
	}
}

void zsda32(buf, length, frameend)
register char *buf;
int length;
int frameend;
{
	register int c;
	register UNSL long crc;

	crc = 0xFFFFFFFFL;
	for (;--length >= 0; ++buf) {
		c = *buf & 0377;
		if (c & 0140)
			xsendline(lastsent = c);
		else
			zsendline(c);
		crc = UPDC32(c, crc);
	}
	xsendline(ZDLE); xsendline(frameend);
	crc = UPDC32(frameend, crc);

	crc = ~crc;
	for (length=4; --length >= 0;) {
		zsendline((int)crc);  crc >>= 8;
	}
}

/*
 * Receive array buf of max length with ending ZDLE sequence
 *  and CRC.  Returns the ending character or error code.
 *  NB: On errors may store length+1 bytes!
 */
int zrdata(buf, length)
register char *buf;
int length;
{
	register int c;
	register unsigned short crc;
	register char *end;
	register int d;

	if (Rxframeind == ZBIN32)
		return zrdat32(buf, length);

	crc = Rxcount = 0;  end = buf + length;
	while (buf <= end) {
		if ((c = zdlread()) & ~0377) {
crcfoo:
			switch (c) {
			case GOTCRCE:
			case GOTCRCG:
			case GOTCRCQ:
			case GOTCRCW:
				crc = updcrc((d=c)&0377, crc);
				if ((c = zdlread()) & ~0377)
					goto crcfoo;
				crc = updcrc(c, crc);
				if ((c = zdlread()) & ~0377)
					goto crcfoo;
				crc = updcrc(c, crc);
				if (crc & 0xFFFF) {
					zperr(badcrc);
					return ERROR;
				}
				Rxcount = length - (end - buf);
				vfile("zrdata: %d  %s", Rxcount,
				 Zendnames[(d-GOTCRCE)&3]);
				return d;
			case GOTCAN:
				zperr("Sender Canceled");
				return ZCAN;
			case TIMEOUT:
				zperr("TIMEOUT");
				return c;
			default:
				zperr("Bad data subpacket");
				return c;
			}
		}
		*buf++ = c;
		crc = updcrc(c, crc);
	}
	zperr("Data subpacket too long");
	return ERROR;
}

int zrdat32(buf, length)
register char *buf;
int length;
{
	register int c;
	register UNSL long crc;
	register char *end;
	register int d;

	crc = 0xFFFFFFFFL;  Rxcount = 0;  end = buf + length;
	while (buf <= end) {
		if ((c = zdlread()) & ~0377) {
crcfoo:
			switch (c) {
			case GOTCRCE:
			case GOTCRCG:
			case GOTCRCQ:
			case GOTCRCW:
				d = c;  c &= 0377;
				crc = UPDC32(c, crc);
				if ((c = zdlread()) & ~0377)
					goto crcfoo;
				crc = UPDC32(c, crc);
				if ((c = zdlread()) & ~0377)
					goto crcfoo;
				crc = UPDC32(c, crc);
				if ((c = zdlread()) & ~0377)
					goto crcfoo;
				crc = UPDC32(c, crc);
				if ((c = zdlread()) & ~0377)
					goto crcfoo;
				crc = UPDC32(c, crc);
				if (crc != 0xDEBB20E3) {
					zperr(badcrc);
					return ERROR;
				}
				Rxcount = length - (end - buf);
				vfile("zrdat32: %d %s", Rxcount,
				 Zendnames[(d-GOTCRCE)&3]);
				return d;
			case GOTCAN:
				zperr("Sender Canceled");
				return ZCAN;
			case TIMEOUT:
				zperr("TIMEOUT");
				return c;
			default:
				zperr("Bad data subpacket");
				return c;
			}
		}
		*buf++ = c;
		crc = UPDC32(c, crc);
	}
	zperr("Data subpacket too long");
	return ERROR;
}


/*
 * Read a ZMODEM header to hdr, either binary or hex.
 *  eflag controls local display of non zmodem characters:
 *	0:  no display
 *	1:  display printing characters only
 *	2:  display all non ZMODEM characters
 *  On success, set Zmodem to 1, set Rxpos and return type of header.
 *   Otherwise return negative on error.
 *   Return ERROR instantly if ZCRCW sequence, for fast error recovery.
 */
int zgethdr(hdr, eflag)
char *hdr;
int eflag;
{
	register int c, n, cancount;

	n = Zrwindow + Baudrate;	/* Max bytes before start of frame */
	Rxframeind = Rxtype = 0;

startover:
	cancount = 5;
again:
	/* Return immediate ERROR if ZCRCW sequence seen */
	switch (c = readline(Rxtimeout)) {
	case RCDO:
	case TIMEOUT:
		goto fifi;
	case CAN:
gotcan:
		if (--cancount <= 0) {
			c = ZCAN; goto fifi;
		}
		switch (c = readline(1)) {
		case TIMEOUT:
			goto again;
		case ZCRCW:
			c = ERROR;
		/* **** FALL THRU TO **** */
		case RCDO:
			goto fifi;
		default:
			break;
		case CAN:
			if (--cancount <= 0) {
				c = ZCAN; goto fifi;
			}
			goto again;
		}
	/* **** FALL THRU TO **** */
	default:
agn2:
		if ( --n == 0) {
			zperr("Garbage count exceeded");
			return(ERROR);
		}
		if (eflag && ((c &= 0177) & 0140))
			bttyout(c);
		else if (eflag > 1)
			bttyout(c);
#ifdef UNIX
		fflush(stderr);
#endif
		goto startover;
	case ZPAD|0200:		/* This is what we want. */
		Not8bit = c;
	case ZPAD:		/* This is what we want. */
		break;
	}
	cancount = 5;
splat:
	switch (c = noxrd7()) {
	case ZPAD:
		goto splat;
	case RCDO:
	case TIMEOUT:
		goto fifi;
	default:
		goto agn2;
	case ZDLE:		/* This is what we want. */
		break;
	}

	switch (c = noxrd7()) {
	case RCDO:
	case TIMEOUT:
		goto fifi;
	case ZBIN:
		Rxframeind = ZBIN;  Crc32 = FALSE;
		c =  zrbhdr(hdr);
		break;
	case ZBIN32:
		Crc32 = Rxframeind = ZBIN32;
		c =  zrbhdr32(hdr);
		break;
	case ZHEX:
		Rxframeind = ZHEX;  Crc32 = FALSE;
		c =  zrhhdr(hdr);
		break;
	case CAN:
		goto gotcan;
	default:
		goto agn2;
	}
	Rxpos = hdr[ZP3] & 0377;
	Rxpos = (Rxpos<<8) + (hdr[ZP2] & 0377);
	Rxpos = (Rxpos<<8) + (hdr[ZP1] & 0377);
	Rxpos = (Rxpos<<8) + (hdr[ZP0] & 0377);
fifi:
	switch (c) {
	case GOTCAN:
		c = ZCAN;
	/* **** FALL THRU TO **** */
	case ZNAK:
	case ZCAN:
	case ERROR:
	case TIMEOUT:
	case RCDO:
		zperr("Got %s", frametypes[c+FTOFFSET]);
	/* **** FALL THRU TO **** */
	default:
		if (c >= -3 && c <= FRTYPES)
			vfile("zgethdr: %s %lx", frametypes[c+FTOFFSET], Rxpos);
		else
			vfile("zgethdr: %d %lx", c, Rxpos);
	}
	return c;
}

/* Receive a binary style header (type and position) */
int zrbhdr(hdr)
register char *hdr;
{
	register int c, n;
	register unsigned short crc;

	if ((c = zdlread()) & ~0377)
		return c;
	Rxtype = c;
	crc = updcrc(c, 0);

	for (n=4; --n >= 0; ++hdr) {
		if ((c = zdlread()) & ~0377)
			return c;
		crc = updcrc(c, crc);
		*hdr = c;
	}
	if ((c = zdlread()) & ~0377)
		return c;
	crc = updcrc(c, crc);
	if ((c = zdlread()) & ~0377)
		return c;
	crc = updcrc(c, crc);
	if (crc & 0xFFFF) {
		zperr(badcrc);
		return ERROR;
	}
#ifdef ZMODEM
	Protocol = ZMODEM;
#endif
	Zmodem = 1;
	return Rxtype;
}

/* Receive a binary style header (type and position) with 32 bit FCS */
int zrbhdr32(hdr)
register char *hdr;
{
	register int c, n;
	register UNSL long crc;

	if ((c = zdlread()) & ~0377)
		return c;
	Rxtype = c;
	crc = 0xFFFFFFFFL; crc = UPDC32(c, crc);
#ifdef DEBUGZ
	vfile("zrbhdr32 c=%X  crc=%lX", c, crc);
#endif

	for (n=4; --n >= 0; ++hdr) {
		if ((c = zdlread()) & ~0377)
			return c;
		crc = UPDC32(c, crc);
		*hdr = c;
#ifdef DEBUGZ
		vfile("zrbhdr32 c=%X  crc=%lX", c, crc);
#endif
	}
	for (n=4; --n >= 0;) {
		if ((c = zdlread()) & ~0377)
			return c;
		crc = UPDC32(c, crc);
#ifdef DEBUGZ
		vfile("zrbhdr32 c=%X  crc=%lX", c, crc);
#endif
	}
	if (crc != 0xDEBB20E3) {
		zperr(badcrc);
		return ERROR;
	}
#ifdef ZMODEM
	Protocol = ZMODEM;
#endif
	Zmodem = 1;
	return Rxtype;
}


/* Receive a hex style header (type and position) */
int zrhhdr(hdr)
char *hdr;
{
	register int c;
	register unsigned short crc;
	register int n;

	if ((c = zgethex()) < 0)
		return c;
	Rxtype = c;
	crc = updcrc(c, 0);

	for (n=4; --n >= 0; ++hdr) {
		if ((c = zgethex()) < 0)
			return c;
		crc = updcrc(c, crc);
		*hdr = c;
	}
	if ((c = zgethex()) < 0)
		return c;
	crc = updcrc(c, crc);
	if ((c = zgethex()) < 0)
		return c;
	crc = updcrc(c, crc);
	if (crc & 0xFFFF) {
		zperr(badcrc); return ERROR;
	}
	switch ( c = readline(1)) {
	case 0215:
		Not8bit = c;
		/* **** FALL THRU TO **** */
	case 015:
	 	/* Throw away possible cr/lf */
		switch (c = readline(1)) {
		case 012:
			Not8bit |= c;
		}
	}
#ifdef ZMODEM
	Protocol = ZMODEM;
#endif
	Zmodem = 1; return Rxtype;
}

/* Send a byte as two hex digits */
void zputhex(c)
register int c;
{
	static char	digits[]	= "0123456789abcdef";

	if (Verbose>8)
		vfile("zputhex: %02X", c);
	sendline(digits[(c&0xF0)>>4]);
	sendline(digits[(c)&0xF]);
}

/*
 * Send character c with ZMODEM escape sequence encoding.
 *  Escape XON, XOFF. Escape CR following @ (Telenet net escape)
 */
void zsendline(c)
int c;
{

	/* Quick check for non control characters */
	if (c & 0140)
		xsendline(lastsent = c);
	else {
		switch (c &= 0377) {
		case ZDLE:
			xsendline(ZDLE);
			xsendline (lastsent = (c ^= 0100));
			break;
		case 015:
		case 0215:
			if (!Zctlesc && (lastsent & 0177) != '@')
				goto sendit;
		/* **** FALL THRU TO **** */
		case 020:
		case 021:
		case 023:
		case 0220:
		case 0221:
		case 0223:
			xsendline(ZDLE);
			c ^= 0100;
	sendit:
			xsendline(lastsent = c);
			break;
		default:
			if (Zctlesc && ! (c & 0140)) {
				xsendline(ZDLE);
				c ^= 0100;
			}
			xsendline(lastsent = c);
		}
	}
}

/* Decode two lower case hex digits into an 8 bit byte value */
int zgethex()
{
	register int c;

	c = zgeth1();
	if (Verbose>8)
		vfile("zgethex: %02X", c);
	return c;
}
int zgeth1()
{
	register int c, n;

	if ((c = noxrd7()) < 0)
		return c;
	n = c - '0';
	if (n > 9)
		n -= ('a' - ':');
	if (n & ~0xF)
		return ERROR;
	if ((c = noxrd7()) < 0)
		return c;
	c -= '0';
	if (c > 9)
		c -= ('a' - ':');
	if (c & ~0xF)
		return ERROR;
	c += (n<<4);
	return c;
}

/*
 * Read a byte, checking for ZMODEM escape encoding
 *  including CAN*5 which represents a quick abort
 */
int zdlread()
{
	register int c;

again:
	/* Quick check for non control characters */
	if ((c = readline(Rxtimeout)) & 0140)
		return c;
	switch (c) {
	case ZDLE:
		break;
	case 023:
	case 0223:
	case 021:
	case 0221:
		goto again;
	default:
		if (Zctlesc && !(c & 0140)) {
			goto again;
		}
		return c;
	}
again2:
	if ((c = readline(Rxtimeout)) < 0)
		return c;
	if (c == CAN && (c = readline(Rxtimeout)) < 0)
		return c;
	if (c == CAN && (c = readline(Rxtimeout)) < 0)
		return c;
	if (c == CAN && (c = readline(Rxtimeout)) < 0)
		return c;
	switch (c) {
	case CAN:
		return GOTCAN;
	case ZCRCE:
	case ZCRCG:
	case ZCRCQ:
	case ZCRCW:
		return (c | GOTOR);
	case ZRUB0:
		return 0177;
	case ZRUB1:
		return 0377;
	case 023:
	case 0223:
	case 021:
	case 0221:
		goto again2;
	default:
		if (Zctlesc && ! (c & 0140)) {
			goto again2;
		}
		if ((c & 0140) ==  0100)
			return (c ^ 0100);
		break;
	}
	if (Verbose>1)
		zperr("Bad escape sequence %x", c);
	return ERROR;
}

/*
 * Read a character from the modem line with timeout.
 *  Eat parity, XON and XOFF characters.
 */
int noxrd7()
{
	register int c;

	for (;;) {
		if ((c = readline(Rxtimeout)) < 0)
			return c;
		switch (c &= 0177) {
		case XON:
		case XOFF:
			continue;
		default:
			if (Zctlesc && !(c & 0140))
				continue;
		case '\r':
		case '\n':
		case ZDLE:
			return c;
		}
	}
}

/* Store long integer pos in Txhdr */
void stohdr(pos)
long pos;
{
	Txhdr[ZP0] = pos;
	Txhdr[ZP1] = pos>>8;
	Txhdr[ZP2] = pos>>16;
	Txhdr[ZP3] = pos>>24;
}

/* Recover a long integer from a header */
long
rclhdr(hdr)
register char *hdr;
{
	register long l;

	l = (hdr[ZP3] & 0377);
	l = (l << 8) | (hdr[ZP2] & 0377);
	l = (l << 8) | (hdr[ZP1] & 0377);
	l = (l << 8) | (hdr[ZP0] & 0377);
	return l;
}

/* End of zm.c */
