networking/tftp.c

   1 /* ------------------------------------------------------------------------- */
   2 /* tftp.c                                                                    */
   3 /*                                                                           */
   4 /* A simple tftp client for busybox.                                         */
   5 /* Tries to follow RFC1350.                                                  */
   6 /* Only "octet" mode supported.                                              */
   7 /* Optional blocksize negotiation (RFC2347 + RFC2348)                        */
   8 /*                                                                           */
   9 /* Copyright (C) 2001 Magnus Damm <damm@opensource.se>                       */
  10 /*                                                                           */
  11 /* Parts of the code based on:                                               */
  12 /*                                                                           */
  13 /* atftp:  Copyright (C) 2000 Jean-Pierre Lefebvre <helix@step.polymtl.ca>   */
  14 /*                        and Remi Lefebvre <remi@debian.org>                */
  15 /*                                                                           */
  16 /* utftp:  Copyright (C) 1999 Uwe Ohse <uwe@ohse.de>                         */
  17 /*                                                                           */
  18 /* This program is free software; you can redistribute it and/or modify      */
  19 /* it under the terms of the GNU General Public License as published by      */
  20 /* the Free Software Foundation; either version 2 of the License, or         */
  21 /* (at your option) any later version.                                       */
  22 /*                                                                           */
  23 /* This program is distributed in the hope that it will be useful,           */
  24 /* but WITHOUT ANY WARRANTY; without even the implied warranty of            */
  25 /* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU          */
  26 /* General Public License for more details.                                  */
  27 /*                                                                           */
  28 /* You should have received a copy of the GNU General Public License         */
  29 /* along with this program; if not, write to the Free Software               */
  30 /* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA   */
  31 /*                                                                           */
  32 /* ------------------------------------------------------------------------- */
  33
  34 #include <stdio.h>
  35 #include <stdlib.h>
  36 #include <string.h>
  37 #include <sys/types.h>
  38 #include <sys/socket.h>
  39 #include <sys/time.h>
  40 #include <sys/stat.h>
  41 #include <netdb.h>
  42 #include <netinet/in.h>
  43 #include <arpa/inet.h>
  44 #include <unistd.h>
  45 #include <fcntl.h>
  46
  47 #include "busybox.h"
  48
  49 //#define CONFIG_FEATURE_TFTP_DEBUG
  50
  51 #define TFTP_BLOCKSIZE_DEFAULT 512 /* according to RFC 1350, don't change */
  52 #define TFTP_TIMEOUT 5             /* seconds */
  53
  54 /* opcodes we support */
  55
  56 #define TFTP_RRQ   1
  57 #define TFTP_WRQ   2
  58 #define TFTP_DATA  3
  59 #define TFTP_ACK   4
  60 #define TFTP_ERROR 5
  61 #define TFTP_OACK  6
  62
  63 static const char *tftp_bb_error_msg[] = {
  64         "Undefined error",
  65         "File not found",
  66         "Access violation",
  67         "Disk full or allocation error",
  68         "Illegal TFTP operation",
  69         "Unknown transfer ID",
  70         "File already exists",
  71         "No such user"
  72 };
  73
  74 const int tftp_cmd_get = 1;
  75 const int tftp_cmd_put = 2;
  76
  77 #ifdef CONFIG_FEATURE_TFTP_BLOCKSIZE
  78
  79 static int tftp_blocksize_check(int blocksize, int bufsize)
  80 {
  81         /* Check if the blocksize is valid:
  82          * RFC2348 says between 8 and 65464,
  83          * but our implementation makes it impossible
  84          * to use blocksizes smaller than 22 octets.
  85          */
  86
  87         if ((bufsize && (blocksize > bufsize)) ||
  88             (blocksize < 8) || (blocksize > 65464)) {
  89                 bb_error_msg("bad blocksize");
  90                 return 0;
  91         }
  92
  93         return blocksize;
  94 }
  95
  96 static char *tftp_option_get(char *buf, int len, char *option)
  97 {
  98         int opt_val = 0;
  99         int opt_found = 0;
 100         int k;
 101
 102         while (len > 0) {
 103
 104                 /* Make sure the options are terminated correctly */
 105
 106                 for (k = 0; k < len; k++) {
 107                         if (buf[k] == '\0') {
 108                                 break;
 109                         }
 110                 }
 111
 112                 if (k >= len) {
 113                         break;
 114                 }
 115
 116                 if (opt_val == 0) {
 117                         if (strcasecmp(buf, option) == 0) {
 118                                 opt_found = 1;
 119                         }
 120                 }
 121                 else {
 122                         if (opt_found) {
 123                                 return buf;
 124                         }
 125                 }
 126
 127                 k++;
 128
 129                 buf += k;
 130                 len -= k;
 131
 132                 opt_val ^= 1;
 133         }
 134
 135         return NULL;
 136 }
 137
 138 #endif
 139
 140 static inline int tftp(const int cmd, const struct hostent *host,
 141         const char *remotefile, int localfd, const int port, int tftp_bufsize)
 142 {
 143         const int cmd_get = cmd & tftp_cmd_get;
 144         const int cmd_put = cmd & tftp_cmd_put;
 145         const int bb_tftp_num_retries = 5;
 146
 147         struct sockaddr_in sa;
 148         struct sockaddr_in from;
 149         struct timeval tv;
 150         socklen_t fromlen;
 151         fd_set rfds;
 152         char *cp;
 153         unsigned short tmp;
 154         int socketfd;
 155         int len;
 156         int opcode = 0;
 157         int finished = 0;
 158         int timeout = bb_tftp_num_retries;
 159         int block_nr = 1;
 160
 161 #ifdef CONFIG_FEATURE_TFTP_BLOCKSIZE
 162         int want_option_ack = 0;
 163 #endif
 164
 165         /* Can't use RESERVE_CONFIG_BUFFER here since the allocation
 166          * size varies meaning BUFFERS_GO_ON_STACK would fail */
 167         char *buf=xmalloc(tftp_bufsize + 4);
 168
 169         tftp_bufsize += 4;
 170
 171         if ((socketfd = socket(PF_INET, SOCK_DGRAM, 0)) < 0) {
 172                 bb_perror_msg("socket");
 173                 return EXIT_FAILURE;
 174         }
 175
 176         len = sizeof(sa);
 177
 178         memset(&sa, 0, len);
 179         bind(socketfd, (struct sockaddr *)&sa, len);
 180
 181         sa.sin_family = host->h_addrtype;
 182         sa.sin_port = htons(port);
 183         memcpy(&sa.sin_addr, (struct in_addr *) host->h_addr,
 184                    sizeof(sa.sin_addr));
 185
 186         /* build opcode */
 187
 188         if (cmd_get) {
 189                 opcode = TFTP_RRQ;
 190         }
 191
 192         if (cmd_put) {
 193                 opcode = TFTP_WRQ;
 194         }
 195
 196         while (1) {
 197
 198                 cp = buf;
 199
 200                 /* first create the opcode part */
 201
 202                 *((unsigned short *) cp) = htons(opcode);
 203
 204                 cp += 2;
 205
 206                 /* add filename and mode */
 207
 208                 if ((cmd_get && (opcode == TFTP_RRQ)) ||
 209                         (cmd_put && (opcode == TFTP_WRQ))) {
 210                         int too_long = 0;
 211
 212                         /* see if the filename fits into buf */
 213                         /* and fill in packet                */
 214
 215                         len = strlen(remotefile) + 1;
 216
 217                         if ((cp + len) >= &buf[tftp_bufsize - 1]) {
 218                                 too_long = 1;
 219                         }
 220                         else {
 221                                 safe_strncpy(cp, remotefile, len);
 222                                 cp += len;
 223                         }
 224
 225                         if (too_long || ((&buf[tftp_bufsize - 1] - cp) < 6)) {
 226                                 bb_error_msg("too long remote-filename");
 227                                 break;
 228                         }
 229
 230                         /* add "mode" part of the package */
 231
 232                         memcpy(cp, "octet", 6);
 233                         cp += 6;
 234
 235 #ifdef CONFIG_FEATURE_TFTP_BLOCKSIZE
 236
 237                         len = tftp_bufsize - 4; /* data block size */
 238
 239                         if (len != TFTP_BLOCKSIZE_DEFAULT) {
 240
 241                                 if ((&buf[tftp_bufsize - 1] - cp) < 15) {
 242                                         bb_error_msg("too long remote-filename");
 243                                         break;
 244                                 }
 245
 246                                 /* add "blksize" + number of blocks  */
 247
 248                                 memcpy(cp, "blksize", 8);
 249                                 cp += 8;
 250
 251                                 cp += snprintf(cp, 6, "%d", len) + 1;
 252
 253                                 want_option_ack = 1;
 254                         }
 255 #endif
 256                 }
 257
 258                 /* add ack and data */
 259
 260                 if ((cmd_get && (opcode == TFTP_ACK)) ||
 261                         (cmd_put && (opcode == TFTP_DATA))) {
 262
 263                         *((unsigned short *) cp) = htons(block_nr);
 264
 265                         cp += 2;
 266
 267                         block_nr++;
 268
 269                         if (cmd_put && (opcode == TFTP_DATA)) {
 270                                 len = read(localfd, cp, tftp_bufsize - 4);
 271
 272                                 if (len < 0) {
 273                                         bb_perror_msg("read");
 274                                         break;
 275                                 }
 276
 277                                 if (len != (tftp_bufsize - 4)) {
 278                                         finished++;
 279                                 }
 280
 281                                 cp += len;
 282                         }
 283                 }
 284
 285
 286                 /* send packet */
 287
 288
 289                 timeout = bb_tftp_num_retries;  /* re-initialize */
 290                 do {
 291
 292                         len = cp - buf;
 293
 294 #ifdef CONFIG_FEATURE_TFTP_DEBUG
 295                         printf("sending %u bytes\n", len);
 296                         for (cp = buf; cp < &buf[len]; cp++)
 297                                 printf("%02x ", *cp);
 298                         printf("\n");
 299 #endif
 300                         if (sendto(socketfd, buf, len, 0,
 301                                         (struct sockaddr *) &sa, sizeof(sa)) < 0) {
 302                                 bb_perror_msg("send");
 303                                 len = -1;
 304                                 break;
 305                         }
 306
 307
 308                         if (finished && (opcode == TFTP_ACK)) {
 309                                 break;
 310                         }
 311
 312                         /* receive packet */
 313
 314                         memset(&from, 0, sizeof(from));
 315                         fromlen = sizeof(from);
 316
 317                         tv.tv_sec = TFTP_TIMEOUT;
 318                         tv.tv_usec = 0;
 319
 320                         FD_ZERO(&rfds);
 321                         FD_SET(socketfd, &rfds);
 322
 323                         switch (select(FD_SETSIZE, &rfds, NULL, NULL, &tv)) {
 324                         case 1:
 325                                 len = recvfrom(socketfd, buf, tftp_bufsize, 0,
 326                                                 (struct sockaddr *) &from, &fromlen);
 327
 328                                 if (len < 0) {
 329                                         bb_perror_msg("recvfrom");
 330                                         break;
 331                                 }
 332
 333                                 timeout = 0;
 334
 335                                 if (sa.sin_port == htons(port)) {
 336                                         sa.sin_port = from.sin_port;
 337                                 }
 338                                 if (sa.sin_port == from.sin_port) {
 339                                         break;
 340                                 }
 341
 342                                 /* fall-through for bad packets! */
 343                                 /* discard the packet - treat as timeout */
 344                                 timeout = bb_tftp_num_retries;
 345
 346                         case 0:
 347                                 bb_error_msg("timeout");
 348
 349                                 timeout--;
 350                                 if (timeout == 0) {
 351                                         len = -1;
 352                                         bb_error_msg("last timeout");
 353                                 }
 354                                 break;
 355
 356                         default:
 357                                 bb_perror_msg("select");
 358                                 len = -1;
 359                         }
 360
 361                 } while (timeout && (len >= 0));
 362
 363                 if ((finished) || (len < 0)) {
 364                         break;
 365                 }
 366
 367                 /* process received packet */
 368
 369
 370                 opcode = ntohs(*((unsigned short *) buf));
 371                 tmp = ntohs(*((unsigned short *) &buf[2]));
 372
 373 #ifdef CONFIG_FEATURE_TFTP_DEBUG
 374                 printf("received %d bytes: %04x %04x\n", len, opcode, tmp);
 375 #endif
 376
 377                 if (opcode == TFTP_ERROR) {
 378                         char *msg = NULL;
 379
 380                         if (buf[4] != '\0') {
 381                                 msg = &buf[4];
 382                                 buf[tftp_bufsize - 1] = '\0';
 383                         } else if (tmp < (sizeof(tftp_bb_error_msg)
 384                                           / sizeof(char *))) {
 385
 386                                 msg = (char *) tftp_bb_error_msg[tmp];
 387                         }
 388
 389                         if (msg) {
 390                                 bb_error_msg("server says: %s", msg);
 391                         }
 392
 393                         break;
 394                 }
 395
 396 #ifdef CONFIG_FEATURE_TFTP_BLOCKSIZE
 397                 if (want_option_ack) {
 398
 399                          want_option_ack = 0;
 400
 401                          if (opcode == TFTP_OACK) {
 402
 403                                  /* server seems to support options */
 404
 405                                  char *res;
 406
 407                                  res = tftp_option_get(&buf[2], len-2,
 408                                                        "blksize");
 409
 410                                  if (res) {
 411                                          int blksize = atoi(res);
 412
 413                                          if (tftp_blocksize_check(blksize,
 414                                                            tftp_bufsize - 4)) {
 415
 416                                                  if (cmd_put) {
 417                                                          opcode = TFTP_DATA;
 418                                                  }
 419                                                  else {
 420                                                          opcode = TFTP_ACK;
 421                                                  }
 422 #ifdef CONFIG_FEATURE_TFTP_DEBUG
 423                                                  printf("using blksize %u\n", blksize);
 424 #endif
 425                                                  tftp_bufsize = blksize + 4;
 426                                                  block_nr = 0;
 427                                                  continue;
 428                                          }
 429                                  }
 430                                  /* FIXME:
 431                                   * we should send ERROR 8 */
 432                                  bb_error_msg("bad server option");
 433                                  break;
 434                          }
 435
 436                          bb_error_msg("warning: blksize not supported by server"
 437                                    " - reverting to 512");
 438
 439                          tftp_bufsize = TFTP_BLOCKSIZE_DEFAULT + 4;
 440                 }
 441 #endif
 442
 443                 if (cmd_get && (opcode == TFTP_DATA)) {
 444
 445                         if (tmp == block_nr) {
 446
 447                                 len = write(localfd, &buf[4], len - 4);
 448
 449                                 if (len < 0) {
 450                                         bb_perror_msg("write");
 451                                         break;
 452                                 }
 453
 454                                 if (len != (tftp_bufsize - 4)) {
 455                                         finished++;
 456                                 }
 457
 458                                 opcode = TFTP_ACK;
 459                                 continue;
 460                         }
 461                 }
 462
 463                 if (cmd_put && (opcode == TFTP_ACK)) {
 464
 465                         if (tmp == (block_nr - 1)) {
 466                                 if (finished) {
 467                                         break;
 468                                 }
 469
 470                                 opcode = TFTP_DATA;
 471                                 continue;
 472                         }
 473                 }
 474         }
 475
 476 #ifdef CONFIG_FEATURE_CLEAN_UP
 477         close(socketfd);
 478
 479         free(buf);
 480 #endif
 481
 482         return finished ? EXIT_SUCCESS : EXIT_FAILURE;
 483 }
 484
 485 int tftp_main(int argc, char **argv)
 486 {
 487         struct hostent *host = NULL;
 488         char *localfile = NULL;
 489         char *remotefile = NULL;
 490         int port = 69;
 491         int cmd = 0;
 492         int fd = -1;
 493         int flags = 0;
 494         int opt;
 495         int result;
 496         int blocksize = TFTP_BLOCKSIZE_DEFAULT;
 497
 498         /* figure out what to pass to getopt */
 499
 500 #ifdef CONFIG_FEATURE_TFTP_BLOCKSIZE
 501 #define BS "b:"
 502 #else
 503 #define BS
 504 #endif
 505
 506 #ifdef CONFIG_FEATURE_TFTP_GET
 507 #define GET "g"
 508 #else
 509 #define GET
 510 #endif
 511
 512 #ifdef CONFIG_FEATURE_TFTP_PUT
 513 #define PUT "p"
 514 #else
 515 #define PUT
 516 #endif
 517
 518         while ((opt = getopt(argc, argv, BS GET PUT "l:r:")) != -1) {
 519                 switch (opt) {
 520 #ifdef CONFIG_FEATURE_TFTP_BLOCKSIZE
 521                 case 'b':
 522                         blocksize = atoi(optarg);
 523                         if (!tftp_blocksize_check(blocksize, 0)) {
 524                                 return EXIT_FAILURE;
 525                         }
 526                         break;
 527 #endif
 528 #ifdef CONFIG_FEATURE_TFTP_GET
 529                 case 'g':
 530                         cmd = tftp_cmd_get;
 531                         flags = O_WRONLY | O_CREAT;
 532                         break;
 533 #endif
 534 #ifdef CONFIG_FEATURE_TFTP_PUT
 535                 case 'p':
 536                         cmd = tftp_cmd_put;
 537                         flags = O_RDONLY;
 538                         break;
 539 #endif
 540                 case 'l':
 541                         localfile = bb_xstrdup(optarg);
 542                         break;
 543                 case 'r':
 544                         remotefile = bb_xstrdup(optarg);
 545                         break;
 546                 }
 547         }
 548
 549         if ((cmd == 0) || (optind == argc)) {
 550                 bb_show_usage();
 551         }
 552         if(localfile && strcmp(localfile, "-") == 0) {
 553             fd = fileno((cmd==tftp_cmd_get)? stdout : stdin);
 554         }
 555         if(localfile == NULL)
 556             localfile = remotefile;
 557         if(remotefile == NULL)
 558             remotefile = localfile;
 559         if (fd==-1) {
 560             fd = open(localfile, flags, 0644);
 561         }
 562         if (fd < 0) {
 563                 bb_perror_msg_and_die("local file");
 564         }
 565
 566         host = xgethostbyname(argv[optind]);
 567
 568         if (optind + 2 == argc) {
 569                 port = atoi(argv[optind + 1]);
 570         }
 571
 572 #ifdef CONFIG_FEATURE_TFTP_DEBUG
 573         printf("using server \"%s\", remotefile \"%s\", "
 574                 "localfile \"%s\".\n",
 575                 inet_ntoa(*((struct in_addr *) host->h_addr)),
 576                 remotefile, localfile);
 577 #endif
 578
 579         result = tftp(cmd, host, remotefile, fd, port, blocksize);
 580
 581 #ifdef CONFIG_FEATURE_CLEAN_UP
 582         if (!(fd == fileno(stdout) || fd == fileno(stdin))) {
 583             close(fd);
 584         }
 585 #endif
 586         return(result);
 587 }