summaryrefslogtreecommitdiff
path: root/tftp.c
blob: 999b5d706c5c9c6aaf404aabe862a5c770ec3836 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
/* ------------------------------------------------------------------------- */
/* tftp.c                                                                    */
/*                                                                           */
/* A simple tftp client for busybox.                                         */
/* Tries to follow RFC1350.                                                  */
/* Only "octet" mode and 512-byte data blocks are supported.                 */
/*                                                                           */
/* Copyright (C) 2001 Magnus Damm <damm@opensource.se>                       */
/*                                                                           */
/* Parts of the code based on:                                               */
/*                                                                           */
/* atftp:  Copyright (C) 2000 Jean-Pierre Lefebvre <helix@step.polymtl.ca>   */
/*                        and Remi Lefebvre <remi@debian.org>                */
/*                                                                           */
/* utftp:  Copyright (C) 1999 Uwe Ohse <uwe@ohse.de>                         */
/*                                                                           */
/* This program is free software; you can redistribute it and/or modify      */
/* it under the terms of the GNU General Public License as published by      */
/* the Free Software Foundation; either version 2 of the License, or         */
/* (at your option) any later version.                                       */
/*                                                                           */
/* This program is distributed in the hope that it will be useful,           */
/* but WITHOUT ANY WARRANTY; without even the implied warranty of            */
/* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU          */
/* General Public License for more details.                                  */
/*                                                                           */
/* You should have received a copy of the GNU General Public License         */
/* along with this program; if not, write to the Free Software               */
/* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA   */
/*                                                                           */
/* ------------------------------------------------------------------------- */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <sys/stat.h>
#include <netdb.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <fcntl.h>

#include "busybox.h"

//#define BB_FEATURE_TFTP_DEBUG

static const char *tftp_error_msg[] = {
	"Undefined error",
	"File not found",
	"Access violation",
	"Disk full or allocation error",
	"Illegal TFTP operation",
	"Unknown transfer ID",
	"File already exists",
	"No such user"
};

const int tftp_cmd_get = 1;
const int tftp_cmd_put = 2;

static inline int tftp(const int cmd, const struct hostent *host,
	const char *serverfile, int localfd, const int port, int tftp_bufsize)
{
	const int cmd_get = cmd & tftp_cmd_get;
	const int cmd_put = cmd & tftp_cmd_put;
	const int bb_tftp_num_retries = 5;

	struct sockaddr_in sa;
	struct sockaddr_in from;
	struct timeval tv;
	socklen_t fromlen;
	fd_set rfds;
	char *cp;
	unsigned short tmp;
	int socketfd;
	int len;
	int opcode = 0;
	int finished = 0;
	int timeout = bb_tftp_num_retries;
	int block_nr = 1;
	RESERVE_BB_BUFFER(buf, tftp_bufsize + 4); // Why 4 ?

	tftp_bufsize += 4;

	if ((socketfd = socket(PF_INET, SOCK_DGRAM, 0)) < 0) {
		perror_msg("socket");
		return EXIT_FAILURE;
	}

	len = sizeof(sa);

	memset(&sa, 0, len);
	bind(socketfd, (struct sockaddr *)&sa, len);

	sa.sin_family = host->h_addrtype;
	sa.sin_port = htons(port);
	memcpy(&sa.sin_addr, (struct in_addr *) host->h_addr,
		   sizeof(sa.sin_addr));

	/* build opcode */

	if (cmd_get) {
		opcode = 1;	// read request = 1
	}

	if (cmd_put) {
		opcode = 2;	// write request = 2
	}

	while (1) {


		/* build packet of type "opcode" */


		cp = buf;

		*((unsigned short *) cp) = htons(opcode);

		cp += 2;

		/* add filename and mode */

		if ((cmd_get && (opcode == 1)) || // read request = 1
			(cmd_put && (opcode == 2))) { // write request = 2

			/* what is this trying to do ? */
			while (cp != &buf[tftp_bufsize - 1]) {
				if ((*cp = *serverfile++) == '\0')
					break;
				cp++;
			}
			/* and this ? */
			if ((*cp != '\0') || (&buf[tftp_bufsize - 1] - cp) < 7) {
				error_msg("too long server-filename");
				break;
			}

			memcpy(cp + 1, "octet", 6);
			cp += 7;
		}

		/* add ack and data */

		if ((cmd_get && (opcode == 4)) || // acknowledgement = 4
			(cmd_put && (opcode == 3))) { // data packet == 3

			*((unsigned short *) cp) = htons(block_nr);

			cp += 2;

			block_nr++;

			if (cmd_put && (opcode == 3)) { // data packet == 3
				len = read(localfd, cp, tftp_bufsize - 4);

				if (len < 0) {
					perror_msg("read");
					break;
				}

				if (len != (tftp_bufsize - 4)) {
					finished++;
				}

				cp += len;
			} else if (finished) {
				break;
			}
		}


		/* send packet */


		do {

			len = cp - buf;

#ifdef BB_FEATURE_TFTP_DEBUG
			printf("sending %u bytes\n", len);
			for (cp = buf; cp < &buf[len]; cp++)
				printf("%02x ", *cp);
			printf("\n");
#endif
			if (sendto(socketfd, buf, len, 0,
					(struct sockaddr *) &sa, sizeof(sa)) < 0) {
				perror_msg("send");
				len = -1;
				break;
			}


			/* receive packet */


			memset(&from, 0, sizeof(from));
			fromlen = sizeof(from);

			tv.tv_sec = 5; // BB_TFPT_TIMEOUT = 5
			tv.tv_usec = 0;

			FD_ZERO(&rfds);
			FD_SET(socketfd, &rfds);

			switch (select(FD_SETSIZE, &rfds, NULL, NULL, &tv)) {
			case 1:
				len = recvfrom(socketfd, buf, tftp_bufsize, 0,
						(struct sockaddr *) &from, &fromlen);

				if (len < 0) {
					perror_msg("recvfrom");
					break;
				}

				timeout = 0;

				if (sa.sin_port == htons(port)) {
					sa.sin_port = from.sin_port;
				}
				if (sa.sin_port == from.sin_port) {
					break;
				}

				/* fall-through for bad packets! */
				/* discard the packet - treat as timeout */
				timeout = bb_tftp_num_retries;

			case 0:
				error_msg("timeout");

				if (timeout == 0) {
					len = -1;
					error_msg("last timeout");
				} else {
					timeout--;
				}
				break;

			default:
				perror_msg("select");
				len = -1;
			}

		} while (timeout && (len >= 0));

		if (len < 0) {
			break;
		}

		/* process received packet */


		opcode = ntohs(*((unsigned short *) buf));
		tmp = ntohs(*((unsigned short *) &buf[2]));

#ifdef BB_FEATURE_TFTP_DEBUG
		printf("received %d bytes: %04x %04x\n", len, opcode, tmp);
#endif

		if (cmd_get && (opcode == 3)) { // data packet == 3

			if (tmp == block_nr) {
				len = write(localfd, &buf[4], len - 4);

				if (len < 0) {
					perror_msg("write");
					break;
				}

				if (len != (tftp_bufsize - 4)) {
					finished++;
				}

				opcode = 4; // acknowledgement = 4
				continue;
			}
		}

		if (cmd_put && (opcode == 4)) { // acknowledgement = 4

			if (tmp == (block_nr - 1)) {
				if (finished) {
					break;
				}

				opcode = 3; // data packet == 3
				continue;
			}
		}

		if (opcode == 5) { // error code == 5
			char *msg = NULL;

			if (buf[4] != '\0') {
				msg = &buf[4];
				buf[tftp_bufsize - 1] = '\0';
			} else if (tmp < (sizeof(tftp_error_msg) / sizeof(char *))) {
				msg = (char *) tftp_error_msg[tmp];
			}

			if (msg) {
				error_msg("server says: %s", msg);
			}

			break;
		}
	}

	close(socketfd);

	return finished ? EXIT_SUCCESS : EXIT_FAILURE;
}

int tftp_main(int argc, char **argv)
{
	struct hostent *host = NULL;
	char *localfile = NULL;
	char *remotefile = NULL;
	int port = 69;
	int cmd = 0;
	int fd = -1;
	int flags = 0;
	int opt;
	int result;
	int blocksize = 512;

	while ((opt = getopt(argc, argv, "b:gpl:r:")) != -1) {
		switch (opt) {
		case 'b':
			blocksize = atoi(optarg);
			break;
#ifdef BB_FEATURE_TFTP_GET
		case 'g':
			cmd = tftp_cmd_get;
			flags = O_WRONLY | O_CREAT;
			break;
#endif
#ifdef BB_FEATURE_TFTP_PUT
		case 'p':
			cmd = tftp_cmd_put;
			flags = O_RDONLY;
			break;
#endif
		case 'l': 
			localfile = xstrdup(optarg);
			break;
		case 'r':
			remotefile = xstrdup(optarg);
			break;
		}
	}

	if ((cmd == 0) || (optind == argc)) {
		show_usage();
	}

	fd = open(localfile, flags, 0644);
	if (fd < 0) {
		perror_msg_and_die("local file");
	}

	host = xgethostbyname(argv[optind]);

	if (optind + 2 == argc) {
		port = atoi(argv[optind + 1]);
	}

#ifdef BB_FEATURE_TFTP_DEBUG
	printf("using server \"%s\", serverfile \"%s\","
		"localfile \"%s\".\n",
		inet_ntoa(*((struct in_addr *) host->h_addr)),
		remotefile, localfile);
#endif

	result = tftp(cmd, host, remotefile, fd, port, blocksize);
	close(fd);

	return(result);
}