networking/tftp.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * A simple tftp client/server for busybox.
   4  * Tries to follow RFC1350.
   5  * Only "octet" mode supported.
   6  * Optional blocksize negotiation (RFC2347 + RFC2348)
   7  *
   8  * Copyright (C) 2001 Magnus Damm <damm@opensource.se>
   9  *
  10  * Parts of the code based on:
  11  *
  12  * atftp:  Copyright (C) 2000 Jean-Pierre Lefebvre <helix@step.polymtl.ca>
  13  *                        and Remi Lefebvre <remi@debian.org>
  14  *
  15  * utftp:  Copyright (C) 1999 Uwe Ohse <uwe@ohse.de>
  16  *
  17  * tftpd added by Denys Vlasenko & Vladimir Dronnikov
  18  *
  19  * Licensed under GPLv2 or later, see file LICENSE in this source tree.
  20  */
  21
  22 //usage:#define tftp_trivial_usage
  23 //usage:       "[OPTIONS] HOST [PORT]"
  24 //usage:#define tftp_full_usage "\n\n"
  25 //usage:       "Transfer a file from/to tftp server\n"
  26 //usage:     "\nOptions:"
  27 //usage:     "\n        -l FILE Local FILE"
  28 //usage:     "\n        -r FILE Remote FILE"
  29 //usage:        IF_FEATURE_TFTP_GET(
  30 //usage:     "\n        -g      Get file"
  31 //usage:        )
  32 //usage:        IF_FEATURE_TFTP_PUT(
  33 //usage:     "\n        -p      Put file"
  34 //usage:        )
  35 //usage:        IF_FEATURE_TFTP_BLOCKSIZE(
  36 //usage:     "\n        -b SIZE Transfer blocks of SIZE octets"
  37 //usage:        )
  38 //usage:
  39 //usage:#define tftpd_trivial_usage
  40 //usage:       "[-cr] [-u USER] [DIR]"
  41 //usage:#define tftpd_full_usage "\n\n"
  42 //usage:       "Transfer a file on tftp client's request\n"
  43 //usage:       "\n"
  44 //usage:       "tftpd should be used as an inetd service.\n"
  45 //usage:       "tftpd's line for inetd.conf:\n"
  46 //usage:       "        69 dgram udp nowait root tftpd tftpd /files/to/serve\n"
  47 //usage:       "It also can be ran from udpsvd:\n"
  48 //usage:       "        udpsvd -vE 0.0.0.0 69 tftpd /files/to/serve\n"
  49 //usage:     "\nOptions:"
  50 //usage:     "\n        -r      Prohibit upload"
  51 //usage:     "\n        -c      Allow file creation via upload"
  52 //usage:     "\n        -u      Access files as USER"
  53
  54 #include "libbb.h"
  55
  56 #if ENABLE_FEATURE_TFTP_GET || ENABLE_FEATURE_TFTP_PUT
  57
  58 #define TFTP_BLKSIZE_DEFAULT       512  /* according to RFC 1350, don't change */
  59 #define TFTP_BLKSIZE_DEFAULT_STR "512"
  60 /* Was 50 ms but users asked to bump it up a bit */
  61 #define TFTP_TIMEOUT_MS            100
  62 #define TFTP_MAXTIMEOUT_MS        2000
  63 #define TFTP_NUM_RETRIES            12  /* number of backed-off retries */
  64
  65 /* opcodes we support */
  66 #define TFTP_RRQ   1
  67 #define TFTP_WRQ   2
  68 #define TFTP_DATA  3
  69 #define TFTP_ACK   4
  70 #define TFTP_ERROR 5
  71 #define TFTP_OACK  6
  72
  73 /* error codes sent over network (we use only 0, 1, 3 and 8) */
  74 /* generic (error message is included in the packet) */
  75 #define ERR_UNSPEC   0
  76 #define ERR_NOFILE   1
  77 #define ERR_ACCESS   2
  78 /* disk full or allocation exceeded */
  79 #define ERR_WRITE    3
  80 #define ERR_OP       4
  81 #define ERR_BAD_ID   5
  82 #define ERR_EXIST    6
  83 #define ERR_BAD_USER 7
  84 #define ERR_BAD_OPT  8
  85
  86 /* masks coming from getopt32 */
  87 enum {
  88         TFTP_OPT_GET = (1 << 0),
  89         TFTP_OPT_PUT = (1 << 1),
  90         /* pseudo option: if set, it's tftpd */
  91         TFTPD_OPT = (1 << 7) * ENABLE_TFTPD,
  92         TFTPD_OPT_r = (1 << 8) * ENABLE_TFTPD,
  93         TFTPD_OPT_c = (1 << 9) * ENABLE_TFTPD,
  94         TFTPD_OPT_u = (1 << 10) * ENABLE_TFTPD,
  95 };
  96
  97 #if ENABLE_FEATURE_TFTP_GET && !ENABLE_FEATURE_TFTP_PUT
  98 #define IF_GETPUT(...)
  99 #define CMD_GET(cmd) 1
 100 #define CMD_PUT(cmd) 0
 101 #elif !ENABLE_FEATURE_TFTP_GET && ENABLE_FEATURE_TFTP_PUT
 102 #define IF_GETPUT(...)
 103 #define CMD_GET(cmd) 0
 104 #define CMD_PUT(cmd) 1
 105 #else
 106 #define IF_GETPUT(...) __VA_ARGS__
 107 #define CMD_GET(cmd) ((cmd) & TFTP_OPT_GET)
 108 #define CMD_PUT(cmd) ((cmd) & TFTP_OPT_PUT)
 109 #endif
 110 /* NB: in the code below
 111  * CMD_GET(cmd) and CMD_PUT(cmd) are mutually exclusive
 112  */
 113
 114
 115 struct globals {
 116         /* u16 TFTP_ERROR; u16 reason; both network-endian, then error text: */
 117         uint8_t error_pkt[4 + 32];
 118         char *user_opt;
 119         /* used in tftpd_main(), a bit big for stack: */
 120         char block_buf[TFTP_BLKSIZE_DEFAULT];
 121 #if ENABLE_FEATURE_TFTP_PROGRESS_BAR
 122         off_t pos;
 123         off_t size;
 124         const char *file;
 125         bb_progress_t pmt;
 126 #endif
 127 } FIX_ALIASING;
 128 #define G (*(struct globals*)&bb_common_bufsiz1)
 129 struct BUG_G_too_big {
 130         char BUG_G_too_big[sizeof(G) <= COMMON_BUFSIZE ? 1 : -1];
 131 };
 132 #define block_buf        (G.block_buf   )
 133 #define user_opt         (G.user_opt    )
 134 #define error_pkt        (G.error_pkt   )
 135 #define INIT_G() do { } while (0)
 136
 137 #define error_pkt_reason (error_pkt[3])
 138 #define error_pkt_str    (error_pkt + 4)
 139
 140 #if ENABLE_FEATURE_TFTP_PROGRESS_BAR
 141 static void tftp_progress_update(void)
 142 {
 143         bb_progress_update(&G.pmt, 0, G.pos, G.size);
 144 }
 145 static void tftp_progress_init(void)
 146 {
 147         bb_progress_init(&G.pmt, G.file);
 148         tftp_progress_update();
 149 }
 150 static void tftp_progress_done(void)
 151 {
 152         if (is_bb_progress_inited(&G.pmt)) {
 153                 tftp_progress_update();
 154                 bb_putchar_stderr('\n');
 155                 bb_progress_free(&G.pmt);
 156         }
 157 }
 158 #else
 159 # define tftp_progress_init() ((void)0)
 160 # define tftp_progress_done() ((void)0)
 161 #endif
 162
 163 #if ENABLE_FEATURE_TFTP_BLOCKSIZE
 164
 165 static int tftp_blksize_check(const char *blksize_str, int maxsize)
 166 {
 167         /* Check if the blksize is valid:
 168          * RFC2348 says between 8 and 65464,
 169          * but our implementation makes it impossible
 170          * to use blksizes smaller than 22 octets. */
 171         unsigned blksize = bb_strtou(blksize_str, NULL, 10);
 172         if (errno
 173          || (blksize < 24) || (blksize > maxsize)
 174         ) {
 175                 bb_error_msg("bad blocksize '%s'", blksize_str);
 176                 return -1;
 177         }
 178 # if ENABLE_TFTP_DEBUG
 179         bb_error_msg("using blksize %u", blksize);
 180 # endif
 181         return blksize;
 182 }
 183
 184 static char *tftp_get_option(const char *option, char *buf, int len)
 185 {
 186         int opt_val = 0;
 187         int opt_found = 0;
 188         int k;
 189
 190         /* buf points to:
 191          * "opt_name<NUL>opt_val<NUL>opt_name2<NUL>opt_val2<NUL>..." */
 192
 193         while (len > 0) {
 194                 /* Make sure options are terminated correctly */
 195                 for (k = 0; k < len; k++) {
 196                         if (buf[k] == '\0') {
 197                                 goto nul_found;
 198                         }
 199                 }
 200                 return NULL;
 201  nul_found:
 202                 if (opt_val == 0) { /* it's "name" part */
 203                         if (strcasecmp(buf, option) == 0) {
 204                                 opt_found = 1;
 205                         }
 206                 } else if (opt_found) {
 207                         return buf;
 208                 }
 209
 210                 k++;
 211                 buf += k;
 212                 len -= k;
 213                 opt_val ^= 1;
 214         }
 215
 216         return NULL;
 217 }
 218
 219 #endif
 220
 221 static int tftp_protocol(
 222                 /* NULL if tftp, !NULL if tftpd: */
 223                 len_and_sockaddr *our_lsa,
 224                 len_and_sockaddr *peer_lsa,
 225                 const char *local_file
 226                 IF_TFTP(, const char *remote_file)
 227 #if !ENABLE_TFTP
 228 # define remote_file NULL
 229 #endif
 230                 /* 1 for tftp; 1/0 for tftpd depending whether client asked about it: */
 231                 IF_FEATURE_TFTP_BLOCKSIZE(, int want_transfer_size)
 232                 IF_FEATURE_TFTP_BLOCKSIZE(, int blksize))
 233 {
 234 #if !ENABLE_FEATURE_TFTP_BLOCKSIZE
 235         enum { blksize = TFTP_BLKSIZE_DEFAULT };
 236 #endif
 237
 238         struct pollfd pfd[1];
 239 #define socket_fd (pfd[0].fd)
 240         int len;
 241         int send_len;
 242         IF_FEATURE_TFTP_BLOCKSIZE(smallint expect_OACK = 0;)
 243         smallint finished = 0;
 244         uint16_t opcode;
 245         uint16_t block_nr;
 246         uint16_t recv_blk;
 247         int open_mode, local_fd;
 248         int retries, waittime_ms;
 249         int io_bufsize = blksize + 4;
 250         char *cp;
 251         /* Can't use RESERVE_CONFIG_BUFFER here since the allocation
 252          * size varies meaning BUFFERS_GO_ON_STACK would fail.
 253          *
 254          * We must keep the transmit and receive buffers separate
 255          * in case we rcv a garbage pkt - we need to rexmit the last pkt.
 256          */
 257         char *xbuf = xmalloc(io_bufsize);
 258         char *rbuf = xmalloc(io_bufsize);
 259
 260         socket_fd = xsocket(peer_lsa->u.sa.sa_family, SOCK_DGRAM, 0);
 261         setsockopt_reuseaddr(socket_fd);
 262
 263         if (!ENABLE_TFTP || our_lsa) { /* tftpd */
 264                 /* Create a socket which is:
 265                  * 1. bound to IP:port peer sent 1st datagram to,
 266                  * 2. connected to peer's IP:port
 267                  * This way we will answer from the IP:port peer
 268                  * expects, will not get any other packets on
 269                  * the socket, and also plain read/write will work. */
 270                 xbind(socket_fd, &our_lsa->u.sa, our_lsa->len);
 271                 xconnect(socket_fd, &peer_lsa->u.sa, peer_lsa->len);
 272
 273                 /* Is there an error already? Send pkt and bail out */
 274                 if (error_pkt_reason || error_pkt_str[0])
 275                         goto send_err_pkt;
 276
 277                 if (user_opt) {
 278                         struct passwd *pw = xgetpwnam(user_opt);
 279                         change_identity(pw); /* initgroups, setgid, setuid */
 280                 }
 281         }
 282
 283         /* Prepare open mode */
 284         if (CMD_PUT(option_mask32)) {
 285                 open_mode = O_RDONLY;
 286         } else {
 287                 open_mode = O_WRONLY | O_TRUNC | O_CREAT;
 288 #if ENABLE_TFTPD
 289                 if ((option_mask32 & (TFTPD_OPT+TFTPD_OPT_c)) == TFTPD_OPT) {
 290                         /* tftpd without -c */
 291                         open_mode = O_WRONLY | O_TRUNC;
 292                 }
 293 #endif
 294         }
 295
 296         /* Examples of network traffic.
 297          * Note two cases when ACKs with block# of 0 are sent.
 298          *
 299          * Download without options:
 300          * tftp -> "\0\1FILENAME\0octet\0"
 301          *         "\0\3\0\1FILEDATA..." <- tftpd
 302          * tftp -> "\0\4\0\1"
 303          * ...
 304          * Download with option of blksize 16384:
 305          * tftp -> "\0\1FILENAME\0octet\0blksize\00016384\0"
 306          *         "\0\6blksize\00016384\0" <- tftpd
 307          * tftp -> "\0\4\0\0"
 308          *         "\0\3\0\1FILEDATA..." <- tftpd
 309          * tftp -> "\0\4\0\1"
 310          * ...
 311          * Upload without options:
 312          * tftp -> "\0\2FILENAME\0octet\0"
 313          *         "\0\4\0\0" <- tftpd
 314          * tftp -> "\0\3\0\1FILEDATA..."
 315          *         "\0\4\0\1" <- tftpd
 316          * ...
 317          * Upload with option of blksize 16384:
 318          * tftp -> "\0\2FILENAME\0octet\0blksize\00016384\0"
 319          *         "\0\6blksize\00016384\0" <- tftpd
 320          * tftp -> "\0\3\0\1FILEDATA..."
 321          *         "\0\4\0\1" <- tftpd
 322          * ...
 323          */
 324         block_nr = 1;
 325         cp = xbuf + 2;
 326
 327         if (!ENABLE_TFTP || our_lsa) { /* tftpd */
 328                 /* Open file (must be after changing user) */
 329                 local_fd = open(local_file, open_mode, 0666);
 330                 if (local_fd < 0) {
 331                         error_pkt_reason = ERR_NOFILE;
 332                         strcpy((char*)error_pkt_str, "can't open file");
 333                         goto send_err_pkt;
 334                 }
 335 /* gcc 4.3.1 would NOT optimize it out as it should! */
 336 #if ENABLE_FEATURE_TFTP_BLOCKSIZE
 337                 if (blksize != TFTP_BLKSIZE_DEFAULT || want_transfer_size) {
 338                         /* Create and send OACK packet. */
 339                         /* For the download case, block_nr is still 1 -
 340                          * we expect 1st ACK from peer to be for (block_nr-1),
 341                          * that is, for "block 0" which is our OACK pkt */
 342                         opcode = TFTP_OACK;
 343                         goto add_blksize_opt;
 344                 }
 345 #endif
 346                 if (CMD_GET(option_mask32)) {
 347                         /* It's upload and we don't send OACK.
 348                          * We must ACK 1st packet (with filename)
 349                          * as if it is "block 0" */
 350                         block_nr = 0;
 351                 }
 352
 353         } else { /* tftp */
 354                 /* Open file (must be after changing user) */
 355                 local_fd = CMD_GET(option_mask32) ? STDOUT_FILENO : STDIN_FILENO;
 356                 if (NOT_LONE_DASH(local_file))
 357                         local_fd = xopen(local_file, open_mode);
 358 /* Removing #if, or using if() statement instead of #if may lead to
 359  * "warning: null argument where non-null required": */
 360 #if ENABLE_TFTP
 361                 /* tftp */
 362
 363                 /* We can't (and don't really need to) bind the socket:
 364                  * we don't know from which local IP datagrams will be sent,
 365                  * but kernel will pick the same IP every time (unless routing
 366                  * table is changed), thus peer will see dgrams consistently
 367                  * coming from the same IP.
 368                  * We would like to connect the socket, but since peer's
 369                  * UDP code can be less perfect than ours, _peer's_ IP:port
 370                  * in replies may differ from IP:port we used to send
 371                  * our first packet. We can connect() only when we get
 372                  * first reply. */
 373
 374                 /* build opcode */
 375                 opcode = TFTP_WRQ;
 376                 if (CMD_GET(option_mask32)) {
 377                         opcode = TFTP_RRQ;
 378                 }
 379                 /* add filename and mode */
 380                 /* fill in packet if the filename fits into xbuf */
 381                 len = strlen(remote_file) + 1;
 382                 if (2 + len + sizeof("octet") >= io_bufsize) {
 383                         bb_error_msg("remote filename is too long");
 384                         goto ret;
 385                 }
 386                 strcpy(cp, remote_file);
 387                 cp += len;
 388                 /* add "mode" part of the packet */
 389                 strcpy(cp, "octet");
 390                 cp += sizeof("octet");
 391
 392 # if ENABLE_FEATURE_TFTP_BLOCKSIZE
 393                 if (blksize == TFTP_BLKSIZE_DEFAULT && !want_transfer_size)
 394                         goto send_pkt;
 395
 396                 /* Need to add option to pkt */
 397                 if ((&xbuf[io_bufsize - 1] - cp) < sizeof("blksize NNNNN tsize ") + sizeof(off_t)*3) {
 398                         bb_error_msg("remote filename is too long");
 399                         goto ret;
 400                 }
 401                 expect_OACK = 1;
 402 # endif
 403 #endif /* ENABLE_TFTP */
 404
 405 #if ENABLE_FEATURE_TFTP_BLOCKSIZE
 406  add_blksize_opt:
 407                 if (blksize != TFTP_BLKSIZE_DEFAULT) {
 408                         /* add "blksize", <nul>, blksize, <nul> */
 409                         strcpy(cp, "blksize");
 410                         cp += sizeof("blksize");
 411                         cp += snprintf(cp, 6, "%d", blksize) + 1;
 412                 }
 413                 if (want_transfer_size) {
 414                         /* add "tsize", <nul>, size, <nul> (see RFC2349) */
 415                         /* if tftp and downloading, we send "0" (since we opened local_fd with O_TRUNC)
 416                          * and this makes server to send "tsize" option with the size */
 417                         /* if tftp and uploading, we send file size (maybe dont, to not confuse old servers???) */
 418                         /* if tftpd and downloading, we are answering to client's request */
 419                         /* if tftpd and uploading: !want_transfer_size, this code is not executed */
 420                         struct stat st;
 421                         strcpy(cp, "tsize");
 422                         cp += sizeof("tsize");
 423                         st.st_size = 0;
 424                         fstat(local_fd, &st);
 425                         cp += sprintf(cp, "%"OFF_FMT"u", (off_t)st.st_size) + 1;
 426 # if ENABLE_FEATURE_TFTP_PROGRESS_BAR
 427                         /* Save for progress bar. If 0 (tftp downloading),
 428                          * we look at server's reply later */
 429                         G.size = st.st_size;
 430                         if (remote_file && st.st_size)
 431                                 tftp_progress_init();
 432 # endif
 433                 }
 434 #endif
 435                 /* First packet is built, so skip packet generation */
 436                 goto send_pkt;
 437         }
 438
 439         /* Using mostly goto's - continue/break will be less clear
 440          * in where we actually jump to */
 441         while (1) {
 442                 /* Build ACK or DATA */
 443                 cp = xbuf + 2;
 444                 *((uint16_t*)cp) = htons(block_nr);
 445                 cp += 2;
 446                 block_nr++;
 447                 opcode = TFTP_ACK;
 448                 if (CMD_PUT(option_mask32)) {
 449                         opcode = TFTP_DATA;
 450                         len = full_read(local_fd, cp, blksize);
 451                         if (len < 0) {
 452                                 goto send_read_err_pkt;
 453                         }
 454                         if (len != blksize) {
 455                                 finished = 1;
 456                         }
 457                         cp += len;
 458                 }
 459  send_pkt:
 460                 /* Send packet */
 461                 *((uint16_t*)xbuf) = htons(opcode); /* fill in opcode part */
 462                 send_len = cp - xbuf;
 463                 /* NB: send_len value is preserved in code below
 464                  * for potential resend */
 465
 466                 retries = TFTP_NUM_RETRIES;  /* re-initialize */
 467                 waittime_ms = TFTP_TIMEOUT_MS;
 468
 469  send_again:
 470 #if ENABLE_TFTP_DEBUG
 471                 fprintf(stderr, "sending %u bytes\n", send_len);
 472                 for (cp = xbuf; cp < &xbuf[send_len]; cp++)
 473                         fprintf(stderr, "%02x ", (unsigned char) *cp);
 474                 fprintf(stderr, "\n");
 475 #endif
 476                 xsendto(socket_fd, xbuf, send_len, &peer_lsa->u.sa, peer_lsa->len);
 477
 478 #if ENABLE_FEATURE_TFTP_PROGRESS_BAR
 479                 if (ENABLE_TFTP && remote_file) /* tftp */
 480                         G.pos = (block_nr - 1) * (uoff_t)blksize;
 481                 if (is_bb_progress_inited(&G.pmt))
 482                         tftp_progress_update();
 483 #endif
 484                 /* Was it final ACK? then exit */
 485                 if (finished && (opcode == TFTP_ACK))
 486                         goto ret;
 487
 488  recv_again:
 489                 /* Receive packet */
 490                 /*pfd[0].fd = socket_fd;*/
 491                 pfd[0].events = POLLIN;
 492                 switch (safe_poll(pfd, 1, waittime_ms)) {
 493                 default:
 494                         /*bb_perror_msg("poll"); - done in safe_poll */
 495                         goto ret;
 496                 case 0:
 497                         retries--;
 498                         if (retries == 0) {
 499                                 tftp_progress_done();
 500                                 bb_error_msg("timeout");
 501                                 goto ret; /* no err packet sent */
 502                         }
 503
 504                         /* exponential backoff with limit */
 505                         waittime_ms += waittime_ms/2;
 506                         if (waittime_ms > TFTP_MAXTIMEOUT_MS) {
 507                                 waittime_ms = TFTP_MAXTIMEOUT_MS;
 508                         }
 509
 510                         goto send_again; /* resend last sent pkt */
 511                 case 1:
 512                         if (!our_lsa) {
 513                                 /* tftp (not tftpd!) receiving 1st packet */
 514                                 our_lsa = ((void*)(ptrdiff_t)-1); /* not NULL */
 515                                 len = recvfrom(socket_fd, rbuf, io_bufsize, 0,
 516                                                 &peer_lsa->u.sa, &peer_lsa->len);
 517                                 /* Our first dgram went to port 69
 518                                  * but reply may come from different one.
 519                                  * Remember and use this new port (and IP) */
 520                                 if (len >= 0)
 521                                         xconnect(socket_fd, &peer_lsa->u.sa, peer_lsa->len);
 522                         } else {
 523                                 /* tftpd, or not the very first packet:
 524                                  * socket is connect()ed, can just read from it. */
 525                                 /* Don't full_read()!
 526                                  * This is not TCP, one read == one pkt! */
 527                                 len = safe_read(socket_fd, rbuf, io_bufsize);
 528                         }
 529                         if (len < 0) {
 530                                 goto send_read_err_pkt;
 531                         }
 532                         if (len < 4) { /* too small? */
 533                                 goto recv_again;
 534                         }
 535                 }
 536
 537                 /* Process recv'ed packet */
 538                 opcode = ntohs( ((uint16_t*)rbuf)[0] );
 539                 recv_blk = ntohs( ((uint16_t*)rbuf)[1] );
 540 #if ENABLE_TFTP_DEBUG
 541                 fprintf(stderr, "received %d bytes: %04x %04x\n", len, opcode, recv_blk);
 542 #endif
 543                 if (opcode == TFTP_ERROR) {
 544                         static const char errcode_str[] ALIGN1 =
 545                                 "\0"
 546                                 "file not found\0"
 547                                 "access violation\0"
 548                                 "disk full\0"
 549                                 "bad operation\0"
 550                                 "unknown transfer id\0"
 551                                 "file already exists\0"
 552                                 "no such user\0"
 553                                 "bad option";
 554
 555                         const char *msg = "";
 556
 557                         if (len > 4 && rbuf[4] != '\0') {
 558                                 msg = &rbuf[4];
 559                                 rbuf[io_bufsize - 1] = '\0'; /* paranoia */
 560                         } else if (recv_blk <= 8) {
 561                                 msg = nth_string(errcode_str, recv_blk);
 562                         }
 563                         bb_error_msg("server error: (%u) %s", recv_blk, msg);
 564                         goto ret;
 565                 }
 566
 567 #if ENABLE_FEATURE_TFTP_BLOCKSIZE
 568                 if (expect_OACK) {
 569                         expect_OACK = 0;
 570                         if (opcode == TFTP_OACK) {
 571                                 /* server seems to support options */
 572                                 char *res;
 573
 574                                 res = tftp_get_option("blksize", &rbuf[2], len - 2);
 575                                 if (res) {
 576                                         blksize = tftp_blksize_check(res, blksize);
 577                                         if (blksize < 0) {
 578                                                 error_pkt_reason = ERR_BAD_OPT;
 579                                                 goto send_err_pkt;
 580                                         }
 581                                         io_bufsize = blksize + 4;
 582                                 }
 583 # if ENABLE_FEATURE_TFTP_PROGRESS_BAR
 584                                 if (remote_file && G.size == 0) { /* if we don't know it yet */
 585                                         res = tftp_get_option("tsize", &rbuf[2], len - 2);
 586                                         if (res) {
 587                                                 G.size = bb_strtoull(res, NULL, 10);
 588                                                 if (G.size)
 589                                                         tftp_progress_init();
 590                                         }
 591                                 }
 592 # endif
 593                                 if (CMD_GET(option_mask32)) {
 594                                         /* We'll send ACK for OACK,
 595                                          * such ACK has "block no" of 0 */
 596                                         block_nr = 0;
 597                                 }
 598                                 continue;
 599                         }
 600                         /* rfc2347:
 601                          * "An option not acknowledged by the server
 602                          * must be ignored by the client and server
 603                          * as if it were never requested." */
 604                         if (blksize != TFTP_BLKSIZE_DEFAULT)
 605                                 bb_error_msg("falling back to blocksize "TFTP_BLKSIZE_DEFAULT_STR);
 606                         blksize = TFTP_BLKSIZE_DEFAULT;
 607                         io_bufsize = TFTP_BLKSIZE_DEFAULT + 4;
 608                 }
 609 #endif
 610                 /* block_nr is already advanced to next block# we expect
 611                  * to get / block# we are about to send next time */
 612
 613                 if (CMD_GET(option_mask32) && (opcode == TFTP_DATA)) {
 614                         if (recv_blk == block_nr) {
 615                                 int sz = full_write(local_fd, &rbuf[4], len - 4);
 616                                 if (sz != len - 4) {
 617                                         strcpy((char*)error_pkt_str, bb_msg_write_error);
 618                                         error_pkt_reason = ERR_WRITE;
 619                                         goto send_err_pkt;
 620                                 }
 621                                 if (sz != blksize) {
 622                                         finished = 1;
 623                                 }
 624                                 continue; /* send ACK */
 625                         }
 626 /* Disabled to cope with servers with Sorcerer's Apprentice Syndrome */
 627 #if 0
 628                         if (recv_blk == (block_nr - 1)) {
 629                                 /* Server lost our TFTP_ACK.  Resend it */
 630                                 block_nr = recv_blk;
 631                                 continue;
 632                         }
 633 #endif
 634                 }
 635
 636                 if (CMD_PUT(option_mask32) && (opcode == TFTP_ACK)) {
 637                         /* did peer ACK our last DATA pkt? */
 638                         if (recv_blk == (uint16_t) (block_nr - 1)) {
 639                                 if (finished)
 640                                         goto ret;
 641                                 continue; /* send next block */
 642                         }
 643                 }
 644                 /* Awww... recv'd packet is not recognized! */
 645                 goto recv_again;
 646                 /* why recv_again? - rfc1123 says:
 647                  * "The sender (i.e., the side originating the DATA packets)
 648                  *  must never resend the current DATA packet on receipt
 649                  *  of a duplicate ACK".
 650                  * DATA pkts are resent ONLY on timeout.
 651                  * Thus "goto send_again" will ba a bad mistake above.
 652                  * See:
 653                  * http://en.wikipedia.org/wiki/Sorcerer's_Apprentice_Syndrome
 654                  */
 655         } /* end of "while (1)" */
 656  ret:
 657         if (ENABLE_FEATURE_CLEAN_UP) {
 658                 close(local_fd);
 659                 close(socket_fd);
 660                 free(xbuf);
 661                 free(rbuf);
 662         }
 663         return finished == 0; /* returns 1 on failure */
 664
 665  send_read_err_pkt:
 666         strcpy((char*)error_pkt_str, bb_msg_read_error);
 667  send_err_pkt:
 668         if (error_pkt_str[0])
 669                 bb_error_msg("%s", (char*)error_pkt_str);
 670         error_pkt[1] = TFTP_ERROR;
 671         xsendto(socket_fd, error_pkt, 4 + 1 + strlen((char*)error_pkt_str),
 672                         &peer_lsa->u.sa, peer_lsa->len);
 673         return EXIT_FAILURE;
 674 #undef remote_file
 675 }
 676
 677 #if ENABLE_TFTP
 678
 679 int tftp_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 680 int tftp_main(int argc UNUSED_PARAM, char **argv)
 681 {
 682         len_and_sockaddr *peer_lsa;
 683         const char *local_file = NULL;
 684         const char *remote_file = NULL;
 685 # if ENABLE_FEATURE_TFTP_BLOCKSIZE
 686         const char *blksize_str = TFTP_BLKSIZE_DEFAULT_STR;
 687         int blksize;
 688 # endif
 689         int result;
 690         int port;
 691         IF_GETPUT(int opt;)
 692
 693         INIT_G();
 694
 695         /* -p or -g is mandatory, and they are mutually exclusive */
 696         opt_complementary = "" IF_FEATURE_TFTP_GET("g:") IF_FEATURE_TFTP_PUT("p:")
 697                         IF_GETPUT("g--p:p--g:");
 698
 699         IF_GETPUT(opt =) getopt32(argv,
 700                         IF_FEATURE_TFTP_GET("g") IF_FEATURE_TFTP_PUT("p")
 701                                 "l:r:" IF_FEATURE_TFTP_BLOCKSIZE("b:"),
 702                         &local_file, &remote_file
 703                         IF_FEATURE_TFTP_BLOCKSIZE(, &blksize_str));
 704         argv += optind;
 705
 706 # if ENABLE_FEATURE_TFTP_BLOCKSIZE
 707         /* Check if the blksize is valid:
 708          * RFC2348 says between 8 and 65464 */
 709         blksize = tftp_blksize_check(blksize_str, 65564);
 710         if (blksize < 0) {
 711                 //bb_error_msg("bad block size");
 712                 return EXIT_FAILURE;
 713         }
 714 # endif
 715
 716         if (remote_file) {
 717                 if (!local_file) {
 718                         const char *slash = strrchr(remote_file, '/');
 719                         local_file = slash ? slash + 1 : remote_file;
 720                 }
 721         } else {
 722                 remote_file = local_file;
 723         }
 724
 725         /* Error if filename or host is not known */
 726         if (!remote_file || !argv[0])
 727                 bb_show_usage();
 728
 729         port = bb_lookup_port(argv[1], "udp", 69);
 730         peer_lsa = xhost2sockaddr(argv[0], port);
 731
 732 # if ENABLE_TFTP_DEBUG
 733         fprintf(stderr, "using server '%s', remote_file '%s', local_file '%s'\n",
 734                         xmalloc_sockaddr2dotted(&peer_lsa->u.sa),
 735                         remote_file, local_file);
 736 # endif
 737
 738 # if ENABLE_FEATURE_TFTP_PROGRESS_BAR
 739         G.file = remote_file;
 740 # endif
 741         result = tftp_protocol(
 742                 NULL /*our_lsa*/, peer_lsa,
 743                 local_file, remote_file
 744                 IF_FEATURE_TFTP_BLOCKSIZE(, 1 /* want_transfer_size */)
 745                 IF_FEATURE_TFTP_BLOCKSIZE(, blksize)
 746         );
 747         tftp_progress_done();
 748
 749         if (result != EXIT_SUCCESS && NOT_LONE_DASH(local_file) && CMD_GET(opt)) {
 750                 unlink(local_file);
 751         }
 752         return result;
 753 }
 754
 755 #endif /* ENABLE_TFTP */
 756
 757 #if ENABLE_TFTPD
 758 int tftpd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 759 int tftpd_main(int argc UNUSED_PARAM, char **argv)
 760 {
 761         len_and_sockaddr *our_lsa;
 762         len_and_sockaddr *peer_lsa;
 763         char *local_file, *mode;
 764         const char *error_msg;
 765         int opt, result, opcode;
 766         IF_FEATURE_TFTP_BLOCKSIZE(int blksize = TFTP_BLKSIZE_DEFAULT;)
 767         IF_FEATURE_TFTP_BLOCKSIZE(int want_transfer_size = 0;)
 768
 769         INIT_G();
 770
 771         our_lsa = get_sock_lsa(STDIN_FILENO);
 772         if (!our_lsa) {
 773                 /* This is confusing:
 774                  *bb_error_msg_and_die("stdin is not a socket");
 775                  * Better: */
 776                 bb_show_usage();
 777                 /* Help text says that tftpd must be used as inetd service,
 778                  * which is by far the most usual cause of get_sock_lsa
 779                  * failure */
 780         }
 781         peer_lsa = xzalloc(LSA_LEN_SIZE + our_lsa->len);
 782         peer_lsa->len = our_lsa->len;
 783
 784         /* Shifting to not collide with TFTP_OPTs */
 785         opt = option_mask32 = TFTPD_OPT | (getopt32(argv, "rcu:", &user_opt) << 8);
 786         argv += optind;
 787         if (argv[0])
 788                 xchdir(argv[0]);
 789
 790         result = recv_from_to(STDIN_FILENO, block_buf, sizeof(block_buf),
 791                         0 /* flags */,
 792                         &peer_lsa->u.sa, &our_lsa->u.sa, our_lsa->len);
 793
 794         error_msg = "malformed packet";
 795         opcode = ntohs(*(uint16_t*)block_buf);
 796         if (result < 4 || result >= sizeof(block_buf)
 797          || block_buf[result-1] != '\0'
 798          || (IF_FEATURE_TFTP_PUT(opcode != TFTP_RRQ) /* not download */
 799              IF_GETPUT(&&)
 800              IF_FEATURE_TFTP_GET(opcode != TFTP_WRQ) /* not upload */
 801             )
 802         ) {
 803                 goto err;
 804         }
 805         local_file = block_buf + 2;
 806         if (local_file[0] == '.' || strstr(local_file, "/.")) {
 807                 error_msg = "dot in file name";
 808                 goto err;
 809         }
 810         mode = local_file + strlen(local_file) + 1;
 811         if (mode >= block_buf + result || strcmp(mode, "octet") != 0) {
 812                 goto err;
 813         }
 814 # if ENABLE_FEATURE_TFTP_BLOCKSIZE
 815         {
 816                 char *res;
 817                 char *opt_str = mode + sizeof("octet");
 818                 int opt_len = block_buf + result - opt_str;
 819                 if (opt_len > 0) {
 820                         res = tftp_get_option("blksize", opt_str, opt_len);
 821                         if (res) {
 822                                 blksize = tftp_blksize_check(res, 65564);
 823                                 if (blksize < 0) {
 824                                         error_pkt_reason = ERR_BAD_OPT;
 825                                         /* will just send error pkt */
 826                                         goto do_proto;
 827                                 }
 828                         }
 829                         if (opcode != TFTP_WRQ /* download? */
 830                         /* did client ask us about file size? */
 831                          && tftp_get_option("tsize", opt_str, opt_len)
 832                         ) {
 833                                 want_transfer_size = 1;
 834                         }
 835                 }
 836         }
 837 # endif
 838
 839         if (!ENABLE_FEATURE_TFTP_PUT || opcode == TFTP_WRQ) {
 840                 if (opt & TFTPD_OPT_r) {
 841                         /* This would mean "disk full" - not true */
 842                         /*error_pkt_reason = ERR_WRITE;*/
 843                         error_msg = bb_msg_write_error;
 844                         goto err;
 845                 }
 846                 IF_GETPUT(option_mask32 |= TFTP_OPT_GET;) /* will receive file's data */
 847         } else {
 848                 IF_GETPUT(option_mask32 |= TFTP_OPT_PUT;) /* will send file's data */
 849         }
 850
 851         /* NB: if error_pkt_str or error_pkt_reason is set up,
 852          * tftp_protocol() just sends one error pkt and returns */
 853
 854  do_proto:
 855         close(STDIN_FILENO); /* close old, possibly wildcard socket */
 856         /* tftp_protocol() will create new one, bound to particular local IP */
 857         result = tftp_protocol(
 858                 our_lsa, peer_lsa,
 859                 local_file IF_TFTP(, NULL /*remote_file*/)
 860                 IF_FEATURE_TFTP_BLOCKSIZE(, want_transfer_size)
 861                 IF_FEATURE_TFTP_BLOCKSIZE(, blksize)
 862         );
 863
 864         return result;
 865  err:
 866         strcpy((char*)error_pkt_str, error_msg);
 867         goto do_proto;
 868 }
 869
 870 #endif /* ENABLE_TFTPD */
 871
 872 #endif /* ENABLE_FEATURE_TFTP_GET || ENABLE_FEATURE_TFTP_PUT */