/*	Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T	*/
/*	  All Rights Reserved  	*/

/*	THIS IS UNPUBLISHED PROPRIETARY SOURCE CODE OF AT&T	*/
/*	The copyright notice above does not evidence any   	*/
/*	actual or intended publication of such source code.	*/

#pragma ident	"@(#)tftpsubs.c	1.10	99/03/21 SMI"	/* SVr4.0 1.3	*/

/*
 * +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 * 		PROPRIETARY NOTICE (Combined)
 *
 * This source code is unpublished proprietary information
 * constituting, or derived under license from AT&T's UNIX(r) System V.
 * In addition, portions of such source code were derived from Berkeley
 * 4.3 BSD under license from the Regents of the University of
 * California.
 *
 *
 *
 * 		Copyright Notice
 *
 * Notice of copyright on this source code product does not indicate
 * publication.
 *
 * 	(c) 1986,1987,1988.1989  Sun Microsystems, Inc
 * 	(c) 1983,1984,1985,1986,1987,1988,1989  AT&T.
 *	All rights reserved.
 *
 */


/*
 * Simple minded read-ahead/write-behind subroutines for tftp user and
 * server.  Written originally with multiple buffers in mind, but current
 * implementation has two buffer logic wired in.
 *
 * Todo:  add some sort of final error check so when the write-buffer
 * is finally flushed, the caller can detect if the disk filled up
 * (or had an i/o error) and return a nak to the other side.
 */

#include <sys/types.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <sys/filio.h>
#include <netinet/in.h>
#include <arpa/tftp.h>
#include <stdio.h>

#ifdef TLI
#include <tiuser.h>

extern int recvfrom_tli();
#define	recvfrom recvfrom_tli
#endif TLI

#define	PKTSIZE SEGSIZE+4	/* should be moved to tftp.h */

struct bf {
	int counter;	/* size of data in buffer, or flag */
	char buf[PKTSIZE];	/* room for data packet */
} bfs[2];

				/* Values for bf.counter  */
#define	BF_ALLOC -3	/* alloc'd but not yet filled */
#define	BF_FREE  -2	/* free */
/* [-1 .. SEGSIZE] = size of data in the data buffer */

static int nextone;	/* index of next buffer to use */
static int current;	/* index of buffer in use */

			/* control flags for crlf conversions */
int newline = 0;	/* fillbuf: in middle of newline expansion */
int prevchar = -1;	/* putbuf: previous char (cr check) */

struct tftphdr *rw_init();

struct tftphdr *w_init() { return (rw_init(0)); }	/* write-behind */
struct tftphdr *r_init() { return (rw_init(1)); }	/* read-ahead */

struct tftphdr *
rw_init(x)	/* init for either read-ahead or write-behind */
int x;	/* zero for write-behind, one for read-head */
{
	newline = 0;	/* init crlf flag */
	prevchar = -1;
	bfs[0].counter =  BF_ALLOC;	/* pass out the first buffer */
	current = 0;
	bfs[1].counter = BF_FREE;
	nextone = x;	/* ahead or behind? */
	return ((struct tftphdr *)bfs[0].buf);
}


/*
 * Have emptied current buffer by sending to net and getting ack.
 * Free it and return next buffer filled with data.
 */
readit(file, dpp, convert)
	FILE *file;	/* file opened for read */
	struct tftphdr **dpp;
	int convert;	/* if true, convert to ascii */
{
	struct bf *b;

	bfs[current].counter = BF_FREE; /* free old one */
	current = !current;	/* "incr" current */

	b = &bfs[current];	/* look at new buffer */
	if (b->counter == BF_FREE)	/* if it's empty */
		read_ahead(file, convert);	/* fill it */
/*	assert(b->counter != BF_FREE); */	/* check */
	*dpp = (struct tftphdr *)b->buf;	/* set caller's ptr */
	return (b->counter);
}

/*
 * fill the input buffer, doing ascii conversions if requested
 * conversions are  lf -> cr,lf  and cr -> cr, nul
 */
read_ahead(file, convert)
	FILE *file;	/* file opened for read */
	int convert;	/* if true, convert to ascii */
{
	register int i;
	register char *p;
	register int c;
	struct bf *b;
	struct tftphdr *dp;

	b = &bfs[nextone];	/* look at "next" buffer */
	if (b->counter != BF_FREE)	/* nop if not free */
		return;
	nextone = !nextone;	/* "incr" next buffer ptr */

	dp = (struct tftphdr *)b->buf;

	if (convert == 0) {
		b->counter = read(fileno(file), dp->th_data, SEGSIZE);
		return;
	}

	p = dp->th_data;
	for (i = 0; i < SEGSIZE; i++) {
		if (newline) {
			if (prevchar == '\n')
				c = '\n';	/* lf to cr,lf */
			else    c = '\0';	/* cr to cr,nul */
			newline = 0;
		} else {
			c = getc(file);
			if (c == EOF) break;
			if (c == '\n' || c == '\r') {
				prevchar = c;
				c = '\r';
				newline = 1;
			}
		}
		*p++ = c;
	}
	b->counter = (int)(p - dp->th_data);
}

/*
 * Update count associated with the buffer, get new buffer
 * from the queue.  Calls write_behind only if next buffer not
 * available.
 */
writeit(file, dpp, ct, convert)
	FILE *file;
	struct tftphdr **dpp;
	int convert;
{
	bfs[current].counter = ct;	/* set size of data to write */
	current = !current;	/* switch to other buffer */
	if (bfs[current].counter != BF_FREE)	/* if not free */
		write_behind(file, convert);	/* flush it */
	bfs[current].counter = BF_ALLOC;	/* mark as alloc'd */
	*dpp =  (struct tftphdr *)bfs[current].buf;
	return (ct);	/* this is a lie of course */
}

/*
 * Output a buffer to a file, converting from netascii if requested.
 * CR,NUL -> CR  and CR,LF => LF.
 * Note spec is undefined if we get CR as last byte of file or a
 * CR followed by anything else.  In this case we leave it alone.
 */
write_behind(file, convert)
	FILE *file;
	int convert;
{
	char *buf;
	int count;
	register int ct;
	register char *p;
	register int c;	/* current character */
	struct bf *b;
	struct tftphdr *dp;

	b = &bfs[nextone];
	if (b->counter < -1)	/* anything to flush? */
		return (0);	/* just nop if nothing to do */

	count = b->counter;	/* remember byte count */
	b->counter = BF_FREE;	/* reset flag */
	dp = (struct tftphdr *)b->buf;
	nextone = !nextone;	/* incr for next time */
	buf = dp->th_data;

	if (count <= 0)
		return (-1);	/* nak logic? */

	if (convert == 0)
		return (write(fileno(file), buf, count));

	p = buf;
	ct = count;
	while (ct--) {	/* loop over the buffer */
	    c = *p++;	/* pick up a character */
	    if (prevchar == '\r') {	/* if prev char was cr */
		if (c == '\n')	/* if have cr,lf then just */
			    fseek(file, -1, 1);	/* smash lf on top of the cr */
		else
			    if (c == '\0')	/* if have cr,nul then */
				goto skipit;	/* just skip over the putc */
		/* else just fall through and allow it */
	    }
	    putc(c, file);
skipit:
	    prevchar = c;
	}
	return (count);
}


/*
 * When an error has occurred, it is possible that the two sides
 * are out of synch.  Ie: that what I think is the other side's
 * response to packet N is really their response to packet N-1.
 *
 * So, to try to prevent that, we flush all the input queued up
 * for us on the network connection on our host.
 *
 * We return the number of packets we flushed (mostly for reporting
 * when trace is active).
 */

int
synchnet(f)
int	f;		/* socket to flush */
{
	int i, j = 0;
	char rbuf[PKTSIZE];
	struct sockaddr_in6 from;
	socklen_t fromlen;

	while (1) {
		(void) ioctl(f, FIONREAD, &i);
		if (i) {
			j++;
			fromlen = (socklen_t)sizeof (from);
			(void) recvfrom(f, rbuf, sizeof (rbuf), 0,
				(struct sockaddr *)&from, &fromlen);
		} else {
			return (j);
		}
	}
}
