tftpsubs.c revision 1.1 
1/*	$NetBSD: tftpsubs.c,v 1.3 1994/12/08 09:51:31 jtc Exp $	*/
2
3/*
4 * Copyright (c) 1983, 1993
5 *	The Regents of the University of California.  All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 * 3. All advertising materials mentioning features or use of this software
16 *    must display the following acknowledgement:
17 *	This product includes software developed by the University of
18 *	California, Berkeley and its contributors.
19 * 4. Neither the name of the University nor the names of its contributors
20 *    may be used to endorse or promote products derived from this software
21 *    without specific prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * SUCH DAMAGE.
34 */
35
36#ifndef lint
37#if 0
38static char sccsid[] = "@(#)tftpsubs.c	8.1 (Berkeley) 6/6/93";
39#endif
40static char rcsid[] = "$NetBSD: tftpsubs.c,v 1.3 1994/12/08 09:51:31 jtc Exp $";
41#endif /* not lint */
42
43/* Simple minded read-ahead/write-behind subroutines for tftp user and
44   server.  Written originally with multiple buffers in mind, but current
45   implementation has two buffer logic wired in.
46
47   Todo:  add some sort of final error check so when the write-buffer
48   is finally flushed, the caller can detect if the disk filled up
49   (or had an i/o error) and return a nak to the other side.
50
51			Jim Guyton 10/85
52 */
53
54#include <sys/types.h>
55#include <sys/socket.h>
56#include <sys/ioctl.h>
57#include <netinet/in.h>
58#include <arpa/tftp.h>
59
60#include <stdio.h>
61#include <unistd.h>
62
63#include "tftpsubs.h"
64
65#define PKTSIZE SEGSIZE+4       /* should be moved to tftp.h */
66
67struct bf {
68	int counter;            /* size of data in buffer, or flag */
69	char buf[PKTSIZE];      /* room for data packet */
70} bfs[2];
71
72				/* Values for bf.counter  */
73#define BF_ALLOC -3             /* alloc'd but not yet filled */
74#define BF_FREE  -2             /* free */
75/* [-1 .. SEGSIZE] = size of data in the data buffer */
76
77static int nextone;		/* index of next buffer to use */
78static int current;		/* index of buffer in use */
79
80				/* control flags for crlf conversions */
81int newline = 0;		/* fillbuf: in middle of newline expansion */
82int prevchar = -1;		/* putbuf: previous char (cr check) */
83
84static struct tftphdr *rw_init();
85
86struct tftphdr *w_init() { return rw_init(0); }         /* write-behind */
87struct tftphdr *r_init() { return rw_init(1); }         /* read-ahead */
88
89static struct tftphdr *
90rw_init(x)			/* init for either read-ahead or write-behind */
91	int x;			/* zero for write-behind, one for read-head */
92{
93	newline = 0;		/* init crlf flag */
94	prevchar = -1;
95	bfs[0].counter =  BF_ALLOC;     /* pass out the first buffer */
96	current = 0;
97	bfs[1].counter = BF_FREE;
98	nextone = x;                    /* ahead or behind? */
99	return (struct tftphdr *)bfs[0].buf;
100}
101
102
103/* Have emptied current buffer by sending to net and getting ack.
104   Free it and return next buffer filled with data.
105 */
106int
107readit(file, dpp, convert)
108	FILE *file;                     /* file opened for read */
109	struct tftphdr **dpp;
110	int convert;                    /* if true, convert to ascii */
111{
112	struct bf *b;
113
114	bfs[current].counter = BF_FREE; /* free old one */
115	current = !current;             /* "incr" current */
116
117	b = &bfs[current];              /* look at new buffer */
118	if (b->counter == BF_FREE)      /* if it's empty */
119		read_ahead(file, convert);      /* fill it */
120/*      assert(b->counter != BF_FREE);*//* check */
121	*dpp = (struct tftphdr *)b->buf;        /* set caller's ptr */
122	return b->counter;
123}
124
125/*
126 * fill the input buffer, doing ascii conversions if requested
127 * conversions are  lf -> cr,lf  and cr -> cr, nul
128 */
129void
130read_ahead(file, convert)
131	FILE *file;                     /* file opened for read */
132	int convert;                    /* if true, convert to ascii */
133{
134	register int i;
135	register char *p;
136	register int c;
137	struct bf *b;
138	struct tftphdr *dp;
139
140	b = &bfs[nextone];              /* look at "next" buffer */
141	if (b->counter != BF_FREE)      /* nop if not free */
142		return;
143	nextone = !nextone;             /* "incr" next buffer ptr */
144
145	dp = (struct tftphdr *)b->buf;
146
147	if (convert == 0) {
148		b->counter = read(fileno(file), dp->th_data, SEGSIZE);
149		return;
150	}
151
152	p = dp->th_data;
153	for (i = 0 ; i < SEGSIZE; i++) {
154		if (newline) {
155			if (prevchar == '\n')
156				c = '\n';       /* lf to cr,lf */
157			else    c = '\0';       /* cr to cr,nul */
158			newline = 0;
159		}
160		else {
161			c = getc(file);
162			if (c == EOF) break;
163			if (c == '\n' || c == '\r') {
164				prevchar = c;
165				c = '\r';
166				newline = 1;
167			}
168		}
169	       *p++ = c;
170	}
171	b->counter = (int)(p - dp->th_data);
172}
173
174/* Update count associated with the buffer, get new buffer
175   from the queue.  Calls write_behind only if next buffer not
176   available.
177 */
178int
179writeit(file, dpp, ct, convert)
180	FILE *file;
181	struct tftphdr **dpp;
182	int ct, convert;
183{
184	bfs[current].counter = ct;      /* set size of data to write */
185	current = !current;             /* switch to other buffer */
186	if (bfs[current].counter != BF_FREE)     /* if not free */
187		(void)write_behind(file, convert); /* flush it */
188	bfs[current].counter = BF_ALLOC;        /* mark as alloc'd */
189	*dpp =  (struct tftphdr *)bfs[current].buf;
190	return ct;                      /* this is a lie of course */
191}
192
193/*
194 * Output a buffer to a file, converting from netascii if requested.
195 * CR,NUL -> CR  and CR,LF => LF.
196 * Note spec is undefined if we get CR as last byte of file or a
197 * CR followed by anything else.  In this case we leave it alone.
198 */
199int
200write_behind(file, convert)
201	FILE *file;
202	int convert;
203{
204	char *buf;
205	int count;
206	register int ct;
207	register char *p;
208	register int c;                 /* current character */
209	struct bf *b;
210	struct tftphdr *dp;
211
212	b = &bfs[nextone];
213	if (b->counter < -1)            /* anything to flush? */
214		return 0;               /* just nop if nothing to do */
215
216	count = b->counter;             /* remember byte count */
217	b->counter = BF_FREE;           /* reset flag */
218	dp = (struct tftphdr *)b->buf;
219	nextone = !nextone;             /* incr for next time */
220	buf = dp->th_data;
221
222	if (count <= 0) return -1;      /* nak logic? */
223
224	if (convert == 0)
225		return write(fileno(file), buf, count);
226
227	p = buf;
228	ct = count;
229	while (ct--) {                  /* loop over the buffer */
230	    c = *p++;                   /* pick up a character */
231	    if (prevchar == '\r') {     /* if prev char was cr */
232		if (c == '\n')          /* if have cr,lf then just */
233		   fseek(file, -1, 1);  /* smash lf on top of the cr */
234		else
235		   if (c == '\0')       /* if have cr,nul then */
236			goto skipit;    /* just skip over the putc */
237		/* else just fall through and allow it */
238	    }
239	    putc(c, file);
240skipit:
241	    prevchar = c;
242	}
243	return count;
244}
245
246
247/* When an error has occurred, it is possible that the two sides
248 * are out of synch.  Ie: that what I think is the other side's
249 * response to packet N is really their response to packet N-1.
250 *
251 * So, to try to prevent that, we flush all the input queued up
252 * for us on the network connection on our host.
253 *
254 * We return the number of packets we flushed (mostly for reporting
255 * when trace is active).
256 */
257
258int
259synchnet(f)
260	int	f;		/* socket to flush */
261{
262	int i, j = 0;
263	char rbuf[PKTSIZE];
264	struct sockaddr_in from;
265	int fromlen;
266
267	while (1) {
268		(void) ioctl(f, FIONREAD, &i);
269		if (i) {
270			j++;
271			fromlen = sizeof from;
272			(void) recvfrom(f, rbuf, sizeof (rbuf), 0,
273				(struct sockaddr *)&from, &fromlen);
274		} else {
275			return(j);
276		}
277	}
278}
279