1 /*
2 * Copyright (c) 1983 Regents of the University of California.
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. All advertising materials mentioning features or use of this software
14 * must display the following acknowledgement:
15 * This product includes software developed by the University of
16 * California, Berkeley and its contributors.
17 * 4. Neither the name of the University nor the names of its contributors
18 * may be used to endorse or promote products derived from this software
19 * without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 */
33
34 #ifndef lint
35 /*static char sccsid[] = "from: @(#)tftpsubs.c 5.6 (Berkeley) 2/28/91";*/
36 /* static char rcsid[] = "$Id: tftpsubs.c,v 1.2 1993/08/01 18:07:04 mycroft Exp $"; */
37 #endif /* not lint */
38
39 /* Simple minded read-ahead/write-behind subroutines for tftp user and
40 server. Written originally with multiple buffers in mind, but current
41 implementation has two buffer logic wired in.
42
43 Todo: add some sort of final error check so when the write-buffer
44 is finally flushed, the caller can detect if the disk filled up
45 (or had an i/o error) and return a nak to the other side.
46
47 Jim Guyton 10/85
48 */
49
50 #include <sys/types.h>
51 #include <sys/socket.h>
52 #include <sys/ioctl.h>
53 #include <netinet/in.h>
54 #include <unistd.h>
55 #include <stdio.h>
56
57 #include "tftp.h"
58
59 #define PKTSIZE SEGSIZE+4 /* should be moved to tftp.h */
60
61 struct bf {
62 int counter; /* size of data in buffer, or flag */
63 char buf[PKTSIZE]; /* room for data packet */
64 } bfs[2];
65
66 /* Values for bf.counter */
67 #define BF_ALLOC -3 /* alloc'd but not yet filled */
68 #define BF_FREE -2 /* free */
69 /* [-1 .. SEGSIZE] = size of data in the data buffer */
70
71 static int nextone; /* index of next buffer to use */
72 static int current; /* index of buffer in use */
73
74 /* control flags for crlf conversions */
75 int newline = 0; /* fillbuf: in middle of newline expansion */
76 int prevchar = -1; /* putbuf: previous char (cr check) */
77
78 struct tftphdr *rw_init(int);
79
w_init()80 struct tftphdr *w_init() { return rw_init(0); } /* write-behind */
r_init()81 struct tftphdr *r_init() { return rw_init(1); } /* read-ahead */
82
83 /* init for either read-ahead or write-behind */
84 /* x is zero for write-behind, one for read-head */
rw_init(int x)85 struct tftphdr *rw_init(int x)
86 {
87 newline = 0; /* init crlf flag */
88 prevchar = -1;
89 bfs[0].counter = BF_ALLOC; /* pass out the first buffer */
90 current = 0;
91 bfs[1].counter = BF_FREE;
92 nextone = x; /* ahead or behind? */
93 return (struct tftphdr *)bfs[0].buf;
94 }
95
96
97 /* Have emptied current buffer by sending to net and getting ack.
98 Free it and return next buffer filled with data.
99 */
readit(FILE * file,struct tftphdr ** dpp,int convert)100 int readit(FILE * file, struct tftphdr **dpp, int convert)
101 {
102 struct bf *b;
103
104 bfs[current].counter = BF_FREE; /* free old one */
105 current = !current; /* "incr" current */
106
107 b = &bfs[current]; /* look at new buffer */
108 if (b->counter == BF_FREE) /* if it's empty */
109 read_ahead(file, convert); /* fill it */
110 #if 0
111 assert(b->counter != BF_FREE); /* check */
112 #endif
113 *dpp = (struct tftphdr *)b->buf; /* set caller's ptr */
114 return b->counter;
115 }
116
117 /*
118 * fill the input buffer, doing ascii conversions if requested
119 * conversions are lf -> cr,lf and cr -> cr, nul
120 */
read_ahead(FILE * file,int convert)121 void read_ahead(FILE *file, int convert)
122 {
123 register int i;
124 register char *p;
125 register int c;
126 struct bf *b;
127 struct tftphdr *dp;
128
129 b = &bfs[nextone]; /* look at "next" buffer */
130 if (b->counter != BF_FREE) /* nop if not free */
131 return;
132 nextone = !nextone; /* "incr" next buffer ptr */
133
134 dp = (struct tftphdr *)b->buf;
135
136 if (convert == 0) {
137 b->counter = read(fileno(file), dp->th_data, SEGSIZE);
138 return;
139 }
140
141 p = dp->th_data;
142 for (i = 0 ; i < SEGSIZE; i++) {
143 if (newline) {
144 if (prevchar == '\n')
145 c = '\n'; /* lf to cr,lf */
146 else c = '\0'; /* cr to cr,nul */
147 newline = 0;
148 }
149 else {
150 c = getc(file);
151 if (c == EOF) break;
152 if (c == '\n' || c == '\r') {
153 prevchar = c;
154 c = '\r';
155 newline = 1;
156 }
157 }
158 *p++ = c;
159 }
160 b->counter = (int)(p - dp->th_data);
161 }
162
163 /* Update count associated with the buffer, get new buffer
164 from the queue. Calls write_behind only if next buffer not
165 available.
166 */
writeit(FILE * file,struct tftphdr ** dpp,int ct,int convert)167 int writeit(FILE *file, struct tftphdr **dpp, int ct, int convert)
168 {
169 bfs[current].counter = ct; /* set size of data to write */
170 current = !current; /* switch to other buffer */
171 if (bfs[current].counter != BF_FREE) /* if not free */
172 write_behind(file, convert); /* flush it */
173 bfs[current].counter = BF_ALLOC; /* mark as alloc'd */
174 *dpp = (struct tftphdr *)bfs[current].buf;
175 return ct; /* this is a lie of course */
176 }
177
178 /*
179 * Output a buffer to a file, converting from netascii if requested.
180 * CR,NUL -> CR and CR,LF => LF.
181 * Note spec is undefined if we get CR as last byte of file or a
182 * CR followed by anything else. In this case we leave it alone.
183 */
write_behind(FILE * file,int convert)184 int write_behind(FILE *file, int convert)
185 {
186 char *buf;
187 int count;
188 register int ct;
189 register char *p;
190 register int c; /* current character */
191 struct bf *b;
192 struct tftphdr *dp;
193
194 b = &bfs[nextone];
195 if (b->counter < -1) /* anything to flush? */
196 return 0; /* just nop if nothing to do */
197
198 count = b->counter; /* remember byte count */
199 b->counter = BF_FREE; /* reset flag */
200 dp = (struct tftphdr *)b->buf;
201 nextone = !nextone; /* incr for next time */
202 buf = dp->th_data;
203
204 if (count <= 0) return -1; /* nak logic? */
205
206 if (convert == 0)
207 return write(fileno(file), buf, count);
208
209 p = buf;
210 ct = count;
211 while (ct--) { /* loop over the buffer */
212 c = *p++; /* pick up a character */
213 if (prevchar == '\r') { /* if prev char was cr */
214 if (c == '\n') /* if have cr,lf then just */
215 fseek(file, -1, 1); /* smash lf on top of the cr */
216 else
217 if (c == '\0') /* if have cr,nul then */
218 goto skipit; /* just skip over the putc */
219 /* else just fall through and allow it */
220 }
221 putc(c, file);
222 skipit:
223 prevchar = c;
224 }
225 return count;
226 }
227
228
229 /* When an error has occurred, it is possible that the two sides
230 * are out of synch. Ie: that what I think is the other side's
231 * response to packet N is really their response to packet N-1.
232 *
233 * So, to try to prevent that, we flush all the input queued up
234 * for us on the network connection on our host.
235 *
236 * We return the number of packets we flushed (mostly for reporting
237 * when trace is active).
238 */
239
synchnet(int f)240 int synchnet(int f)
241 {
242 int j = 0;
243 char dummy;
244
245 while (1) {
246 if (recv(f, &dummy, 1, MSG_DONTWAIT) < 0)
247 break;
248 j++;
249 }
250 return j;
251 }
252