zm.c

ZMODEM协议的实现

			}
			goto again;
		}
	/* **** FALL THRU TO **** */
	default:
agn2:
		if ( --n == 0) {
			c = GCOUNT;  goto fifi;
		}
		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;
	}


	Rxhlen = 4;		/* Set default length */
	Rxframeind = c = noxrd7();
	switch (c) {
	case ZVBIN32:
		if ((Rxhlen = c = zdlread()) < 0)
			goto fifi;
		if (c > ZMAXHLEN)
			goto agn2;
		Crc32r = 1;  c = zrbhd32(hdr); break;
	case ZBIN32:
		if (Usevhdrs)
			goto agn2;
		Crc32r = 1;  c = zrbhd32(hdr); break;
	case ZVBINR32:
		if ((Rxhlen = c = zdlread()) < 0)
			goto fifi;
		if (c > ZMAXHLEN)
			goto agn2;
		Crc32r = 2;  c = zrbhd32(hdr); break;
	case ZBINR32:
		if (Usevhdrs)
			goto agn2;
		Crc32r = 2;  c = zrbhd32(hdr); break;
	case RCDO:
	case TIMEOUT:
		goto fifi;
	case ZVBIN:
		if ((Rxhlen = c = zdlread()) < 0)
			goto fifi;
		if (c > ZMAXHLEN)
			goto agn2;
		Crc32r = 0;  c = zrbhdr(hdr); break;
	case ZBIN:
		if (Usevhdrs)
			goto agn2;
		Crc32r = 0;  c = zrbhdr(hdr); break;
	case ZVHEX:
		if ((Rxhlen = c = zgethex()) < 0)
			goto fifi;
		if (c > ZMAXHLEN)
			goto agn2;
		Crc32r = 0;  c = zrhhdr(hdr); break;
	case ZHEX:
		if (Usevhdrs)
			goto agn2;
		Crc32r = 0;  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:
	case GCOUNT:
		zperr("Got %s", frametypes[c+FTOFFSET]);
	/* **** FALL THRU TO **** */
#ifndef DSZ
	default:
		if (c >= -4 && c <= FRTYPES)
			vfile("zgethdr: %c %d %s %lx", Rxframeind, Rxhlen,
			  frametypes[c+FTOFFSET], Rxpos);
		else
			vfile("zgethdr: %c %d %lx", Rxframeind, c, Rxpos);
#endif
	}
	/* Use variable length headers if we got one */
	if (c >= 0 && c <= FRTYPES && Rxframeind & 040)
		Usevhdrs = 1;
	return c;
}

/* Receive a binary style header (type and position) */
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=Rxhlen; --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 */
zrbhd32(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("zrbhd32 c=%X  crc=%lX", c, crc);
#endif

	for (n=Rxhlen; --n >= 0; ++hdr) {
		if ((c = zdlread()) & ~0377)
			return c;
		crc = UPDC32(c, crc);
		*hdr = c;
#ifdef DEBUGZ
		vfile("zrbhd32 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("zrbhd32 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) */
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=Rxhlen; --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 */
zputhex(c)
register int c;
{
	static char	digits[]	= "0123456789abcdef";

#ifdef DEBUGZ
	if (Verbose>8)
		vfile("zputhex: %02X", c);
#endif
	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)
 */
zsendline(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 */
zgethex()
{
	register int c;

	c = zgeth1();
#ifdef DEBUGZ
	if (Verbose>8)
		vfile("zgethex: %02X", c);
#endif
	return c;
}
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
 */
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.
 */
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 */
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 */