Linux debugging

Check our new training course

Linux debugging, tracing, profiling & perf. analysis

Check our new training course
with Creative Commons CC-BY-SA
lecture and lab materials

Bootlin logo

Elixir Cross Referencer

  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
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
/* ------------------------------------------------------------------------- */
/* tftp.c                                                                    */
/*                                                                           */
/* A simple tftp client for busybox.                                         */
/* Tries to follow RFC1350.                                                  */
/* Only "octet" mode supported.                                              */
/* Optional blocksize negotiation (RFC2347 + RFC2348)                        */
/*                                                                           */
/* 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 CONFIG_FEATURE_TFTP_DEBUG

#define TFTP_BLOCKSIZE_DEFAULT 512 /* according to RFC 1350, don't change */
#define TFTP_TIMEOUT 5             /* seconds */

/* opcodes we support */

#define TFTP_RRQ   1
#define TFTP_WRQ   2
#define TFTP_DATA  3
#define TFTP_ACK   4
#define TFTP_ERROR 5
#define TFTP_OACK  6

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;

#ifdef CONFIG_FEATURE_TFTP_BLOCKSIZE

static int tftp_blocksize_check(int blocksize, int bufsize)  
{
        /* Check if the blocksize is valid: 
	 * RFC2348 says between 8 and 65464,
	 * but our implementation makes it impossible
	 * to use blocksizes smaller than 22 octets.
	 */

        if ((bufsize && (blocksize > bufsize)) || 
	    (blocksize < 8) || (blocksize > 65464)) {
	        error_msg("bad blocksize");
	        return 0;
	}

	return blocksize;
}

static char *tftp_option_get(char *buf, int len, char *option)  
{
        int opt_val = 0;
	int opt_found = 0;
	int k;
  
	while (len > 0) {

	        /* Make sure the options are terminated correctly */

	        for (k = 0; k < len; k++) {
		        if (buf[k] == '\0') {
			        break;
			}
		}

		if (k >= len) {
		        break;
		}

		if (opt_val == 0) {
			if (strcasecmp(buf, option) == 0) {
			        opt_found = 1;
			}
		}      
		else {
		        if (opt_found) {
				return buf;
			}
		}
    
		k++;
		
		buf += k;
		len -= k;
		
		opt_val ^= 1;
	}
	
	return NULL;
}

#endif

static inline int tftp(const int cmd, const struct hostent *host,
	const char *remotefile, 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;

#ifdef CONFIG_FEATURE_TFTP_BLOCKSIZE
	int want_option_ack = 0;
#endif

	/* Can't use RESERVE_CONFIG_BUFFER here since the allocation
	 * size varies meaning BUFFERS_GO_ON_STACK would fail */
	char *buf=xmalloc(tftp_bufsize + 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 = TFTP_RRQ;
	}

	if (cmd_put) {
		opcode = TFTP_WRQ;
	}

	while (1) {

		cp = buf;

		/* first create the opcode part */

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

		cp += 2;

		/* add filename and mode */

		if ((cmd_get && (opcode == TFTP_RRQ)) ||
			(cmd_put && (opcode == TFTP_WRQ))) {
                        int too_long = 0; 

			/* see if the filename fits into buf */
			/* and fill in packet                */

			len = strlen(remotefile) + 1;

			if ((cp + len) >= &buf[tftp_bufsize - 1]) {
			        too_long = 1;
			}
			else {
			        safe_strncpy(cp, remotefile, len);
				cp += len;
			}

			if (too_long || ((&buf[tftp_bufsize - 1] - cp) < 6)) {
				error_msg("too long remote-filename");
				break;
			}

			/* add "mode" part of the package */

			memcpy(cp, "octet", 6);
			cp += 6;

#ifdef CONFIG_FEATURE_TFTP_BLOCKSIZE

			len = tftp_bufsize - 4; /* data block size */

			if (len != TFTP_BLOCKSIZE_DEFAULT) {

			        if ((&buf[tftp_bufsize - 1] - cp) < 15) {
				        error_msg("too long remote-filename");
					break;
				}

				/* add "blksize" + number of blocks  */

				memcpy(cp, "blksize", 8);
				cp += 8;

				cp += snprintf(cp, 6, "%d", len) + 1;

				want_option_ack = 1;
			}
#endif
		}

		/* add ack and data */

		if ((cmd_get && (opcode == TFTP_ACK)) ||
			(cmd_put && (opcode == TFTP_DATA))) {

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

			cp += 2;

			block_nr++;

			if (cmd_put && (opcode == TFTP_DATA)) {
				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 CONFIG_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 = TFTP_TIMEOUT;
			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 CONFIG_FEATURE_TFTP_DEBUG
		printf("received %d bytes: %04x %04x\n", len, opcode, tmp);
#endif

		if (opcode == TFTP_ERROR) {
			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;
		}

#ifdef CONFIG_FEATURE_TFTP_BLOCKSIZE
		if (want_option_ack) {

			 want_option_ack = 0;

		         if (opcode == TFTP_OACK) {

			         /* server seems to support options */

			         char *res;

				 res = tftp_option_get(&buf[2], len-2, 
						       "blksize");

				 if (res) {
				         int foo = atoi(res);
			     
					 if (tftp_blocksize_check(foo,
							   tftp_bufsize - 4)) {

					         if (cmd_put) {
				                         opcode = TFTP_DATA;
						 }
						 else {
				                         opcode = TFTP_ACK;
						 }
#ifdef CONFIG_FEATURE_TFTP_DEBUG
						 printf("using blksize %u\n");
#endif
					         tftp_bufsize = foo + 4;
						 block_nr = 0;
						 continue;
					 }
				 }
				 /* FIXME:
				  * we should send ERROR 8 */
				 error_msg("bad server option");
				 break;
			 }

			 error_msg("warning: blksize not supported by server"
				   " - reverting to 512");

			 tftp_bufsize = TFTP_BLOCKSIZE_DEFAULT + 4;
		}
#endif

		if (cmd_get && (opcode == TFTP_DATA)) {

			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 = TFTP_ACK;
				continue;
			}
		}

		if (cmd_put && (opcode == TFTP_ACK)) {

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

				opcode = TFTP_DATA;
				continue;
			}
		}
	}

#ifdef CONFIG_FEATURE_CLEAN_UP
	close(socketfd);

        RELEASE_CONFIG_BUFFER(buf);
#endif

	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 = TFTP_BLOCKSIZE_DEFAULT;

	/* figure out what to pass to getopt */

#ifdef CONFIG_FEATURE_TFTP_BLOCKSIZE
#define BS "b:"
#else
#define BS
#endif

#ifdef CONFIG_FEATURE_TFTP_GET
#define GET "g"
#else
#define GET 
#endif

#ifdef CONFIG_FEATURE_TFTP_PUT
#define PUT "p"
#else
#define PUT 
#endif

	while ((opt = getopt(argc, argv, BS GET PUT "l:r:")) != -1) {
		switch (opt) {
#ifdef CONFIG_FEATURE_TFTP_BLOCKSIZE
		case 'b':
			blocksize = atoi(optarg);
			if (!tftp_blocksize_check(blocksize, 0)) {
                                return EXIT_FAILURE;
			}
			break;
#endif
#ifdef CONFIG_FEATURE_TFTP_GET
		case 'g':
			cmd = tftp_cmd_get;
			flags = O_WRONLY | O_CREAT;
			break;
#endif
#ifdef CONFIG_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 CONFIG_FEATURE_TFTP_DEBUG
	printf("using server \"%s\", remotefile \"%s\", "
		"localfile \"%s\".\n",
		inet_ntoa(*((struct in_addr *) host->h_addr)),
		remotefile, localfile);
#endif

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

#ifdef CONFIG_FEATURE_CLEAN_UP
	close(fd);
#endif
	return(result);
}