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:     "\n        -l FILE Local FILE"
  27 //usage:     "\n        -r FILE Remote FILE"
  28 //usage:        IF_FEATURE_TFTP_GET(
  29 //usage:     "\n        -g      Get file"
  30 //usage:        )
  31 //usage:        IF_FEATURE_TFTP_PUT(
  32 //usage:     "\n        -p      Put file"
  33 //usage:        )
  34 //usage:        IF_FEATURE_TFTP_BLOCKSIZE(
  35 //usage:     "\n        -b SIZE Transfer blocks of SIZE octets"
  36 //usage:        )
  37 //usage:
  38 //usage:#define tftpd_trivial_usage
  39 //usage:       "[-cr] [-u USER] [DIR]"
  40 //usage:#define tftpd_full_usage "\n\n"
  41 //usage:       "Transfer a file on tftp client's request\n"
  42 //usage:       "\n"
  43 //usage:       "tftpd should be used as an inetd service.\n"
  44 //usage:       "tftpd's line for inetd.conf:\n"
  45 //usage:       "        69 dgram udp nowait root tftpd tftpd -l /files/to/serve\n"
  46 //usage:       "It also can be ran from udpsvd:\n"
  47 //usage:       "        udpsvd -vE 0.0.0.0 69 tftpd /files/to/serve\n"
  48 //usage:     "\n        -r      Prohibit upload"
  49 //usage:     "\n        -c      Allow file creation via upload"
  50 //usage:     "\n        -u      Access files as USER"
  51 //usage:     "\n        -l      Log to syslog (inetd mode requires this)"
  52
  53 #include "libbb.h"
  54 #include <syslog.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         TFTPD_OPT_l = (1 << 11) * ENABLE_TFTPD,
  96 };
  97
  98 #if ENABLE_FEATURE_TFTP_GET && !ENABLE_FEATURE_TFTP_PUT
  99 #define IF_GETPUT(...)
 100 #define CMD_GET(cmd) 1
 101 #define CMD_PUT(cmd) 0
 102 #elif !ENABLE_FEATURE_TFTP_GET && ENABLE_FEATURE_TFTP_PUT
 103 #define IF_GETPUT(...)
 104 #define CMD_GET(cmd) 0
 105 #define CMD_PUT(cmd) 1
 106 #else
 107 #define IF_GETPUT(...) __VA_ARGS__
 108 #define CMD_GET(cmd) ((cmd) & TFTP_OPT_GET)
 109 #define CMD_PUT(cmd) ((cmd) & TFTP_OPT_PUT)
 110 #endif
 111 /* NB: in the code below
 112  * CMD_GET(cmd) and CMD_PUT(cmd) are mutually exclusive
 113  */
 114
 115
 116 struct globals {
 117         /* u16 TFTP_ERROR; u16 reason; both network-endian, then error text: */
 118         uint8_t error_pkt[4 + 32];
 119         char *user_opt;
 120         /* used in tftpd_main(), a bit big for stack: */
 121         char block_buf[TFTP_BLKSIZE_DEFAULT];
 122 #if ENABLE_FEATURE_TFTP_PROGRESS_BAR
 123         off_t pos;
 124         off_t size;
 125         const char *file;
 126         bb_progress_t pmt;
 127 #endif
 128 } FIX_ALIASING;
 129 #define G (*(struct globals*)&bb_common_bufsiz1)
 130 struct BUG_G_too_big {
 131         char BUG_G_too_big[sizeof(G) <= COMMON_BUFSIZE ? 1 : -1];
 132 };
 133 #define block_buf        (G.block_buf   )
 134 #define user_opt         (G.user_opt    )
 135 #define error_pkt        (G.error_pkt   )
 136 #define INIT_G() do { } while (0)
 137
 138 #define error_pkt_reason (error_pkt[3])
 139 #define error_pkt_str    (error_pkt + 4)
 140
 141 #if ENABLE_FEATURE_TFTP_PROGRESS_BAR
 142 static void tftp_progress_update(void)
 143 {
 144         bb_progress_update(&G.pmt, 0, G.pos, G.size);
 145 }
 146 static void tftp_progress_init(void)
 147 {
 148         bb_progress_init(&G.pmt, G.file);
 149         tftp_progress_update();
 150 }
 151 static void tftp_progress_done(void)
 152 {
 153         if (is_bb_progress_inited(&G.pmt)) {
 154                 tftp_progress_update();
 155                 bb_putchar_stderr('\n');
 156                 bb_progress_free(&G.pmt);
 157         }
 158 }
 159 #else
 160 # define tftp_progress_init() ((void)0)
 161 # define tftp_progress_done() ((void)0)
 162 #endif
 163
 164 #if ENABLE_FEATURE_TFTP_BLOCKSIZE
 165
 166 static int tftp_blksize_check(const char *blksize_str, int maxsize)
 167 {
 168         /* Check if the blksize is valid:
 169          * RFC2348 says between 8 and 65464,
 170          * but our implementation makes it impossible
 171          * to use blksizes smaller than 22 octets. */
 172         unsigned blksize = bb_strtou(blksize_str, NULL, 10);
 173         if (errno
 174          || (blksize < 24) || (blksize > maxsize)
 175         ) {
 176                 bb_error_msg("bad blocksize '%s'", blksize_str);
 177                 return -1;
 178         }
 179 # if ENABLE_TFTP_DEBUG
 180         bb_error_msg("using blksize %u", blksize);
 181 # endif
 182         return blksize;
 183 }
 184
 185 static char *tftp_get_option(const char *option, char *buf, int len)
 186 {
 187         int opt_val = 0;
 188         int opt_found = 0;
 189         int k;
 190
 191         /* buf points to:
 192          * "opt_name<NUL>opt_val<NUL>opt_name2<NUL>opt_val2<NUL>..." */
 193
 194         while (len > 0) {
 195                 /* Make sure options are terminated correctly */
 196                 for (k = 0; k < len; k++) {
 197                         if (buf[k] == '\0') {
 198                                 goto nul_found;
 199                         }
 200                 }
 201                 return NULL;
 202  nul_found:
 203                 if (opt_val == 0) { /* it's "name" part */
 204                         if (strcasecmp(buf, option) == 0) {
 205                                 opt_found = 1;
 206                         }
 207                 } else if (opt_found) {
 208                         return buf;
 209                 }
 210
 211                 k++;
 212                 buf += k;
 213                 len -= k;
 214                 opt_val ^= 1;
 215         }
 216
 217         return NULL;
 218 }
 219
 220 #endif
 221
 222 static int tftp_protocol(
 223                 /* NULL if tftp, !NULL if tftpd: */
 224                 len_and_sockaddr *our_lsa,
 225                 len_and_sockaddr *peer_lsa,
 226                 const char *local_file
 227                 IF_TFTP(, const char *remote_file)
 228 #if !ENABLE_TFTP
 229 # define remote_file NULL
 230 #endif
 231                 /* 1 for tftp; 1/0 for tftpd depending whether client asked about it: */
 232                 IF_FEATURE_TFTP_BLOCKSIZE(, int want_transfer_size)
 233                 IF_FEATURE_TFTP_BLOCKSIZE(, int blksize))
 234 {
 235 #if !ENABLE_FEATURE_TFTP_BLOCKSIZE
 236         enum { blksize = TFTP_BLKSIZE_DEFAULT };
 237 #endif
 238
 239         struct pollfd pfd[1];
 240 #define socket_fd (pfd[0].fd)
 241         int len;
 242         int send_len;
 243         IF_FEATURE_TFTP_BLOCKSIZE(smallint expect_OACK = 0;)
 244         smallint finished = 0;
 245         uint16_t opcode;
 246         uint16_t block_nr;
 247         uint16_t recv_blk;
 248         int open_mode, local_fd;
 249         int retries, waittime_ms;
 250         int io_bufsize = blksize + 4;
 251         char *cp;
 252         /* Can't use RESERVE_CONFIG_BUFFER here since the allocation
 253          * size varies meaning BUFFERS_GO_ON_STACK would fail.
 254          *
 255          * We must keep the transmit and receive buffers separate
 256          * in case we rcv a garbage pkt - we need to rexmit the last pkt.
 257          */
 258         char *xbuf = xmalloc(io_bufsize);
 259         char *rbuf = xmalloc(io_bufsize);
 260
 261         socket_fd = xsocket(peer_lsa->u.sa.sa_family, SOCK_DGRAM, 0);
 262         setsockopt_reuseaddr(socket_fd);
 263
 264         if (!ENABLE_TFTP || our_lsa) { /* tftpd */
 265                 /* Create a socket which is:
 266                  * 1. bound to IP:port peer sent 1st datagram to,
 267                  * 2. connected to peer's IP:port
 268                  * This way we will answer from the IP:port peer
 269                  * expects, will not get any other packets on
 270                  * the socket, and also plain read/write will work. */
 271                 xbind(socket_fd, &our_lsa->u.sa, our_lsa->len);
 272                 xconnect(socket_fd, &peer_lsa->u.sa, peer_lsa->len);
 273
 274                 /* Is there an error already? Send pkt and bail out */
 275                 if (error_pkt_reason || error_pkt_str[0])
 276                         goto send_err_pkt;
 277
 278                 if (user_opt) {
 279                         struct passwd *pw = xgetpwnam(user_opt);
 280                         change_identity(pw); /* initgroups, setgid, setuid */
 281                 }
 282         }
 283
 284         /* Prepare open mode */
 285         if (CMD_PUT(option_mask32)) {
 286                 open_mode = O_RDONLY;
 287         } else {
 288                 open_mode = O_WRONLY | O_TRUNC | O_CREAT;
 289 #if ENABLE_TFTPD
 290                 if ((option_mask32 & (TFTPD_OPT+TFTPD_OPT_c)) == TFTPD_OPT) {
 291                         /* tftpd without -c */
 292                         open_mode = O_WRONLY | O_TRUNC;
 293                 }
 294 #endif
 295         }
 296
 297         /* Examples of network traffic.
 298          * Note two cases when ACKs with block# of 0 are sent.
 299          *
 300          * Download without options:
 301          * tftp -> "\0\1FILENAME\0octet\0"
 302          *         "\0\3\0\1FILEDATA..." <- tftpd
 303          * tftp -> "\0\4\0\1"
 304          * ...
 305          * Download with option of blksize 16384:
 306          * tftp -> "\0\1FILENAME\0octet\0blksize\00016384\0"
 307          *         "\0\6blksize\00016384\0" <- tftpd
 308          * tftp -> "\0\4\0\0"
 309          *         "\0\3\0\1FILEDATA..." <- tftpd
 310          * tftp -> "\0\4\0\1"
 311          * ...
 312          * Upload without options:
 313          * tftp -> "\0\2FILENAME\0octet\0"
 314          *         "\0\4\0\0" <- tftpd
 315          * tftp -> "\0\3\0\1FILEDATA..."
 316          *         "\0\4\0\1" <- tftpd
 317          * ...
 318          * Upload with option of blksize 16384:
 319          * tftp -> "\0\2FILENAME\0octet\0blksize\00016384\0"
 320          *         "\0\6blksize\00016384\0" <- tftpd
 321          * tftp -> "\0\3\0\1FILEDATA..."
 322          *         "\0\4\0\1" <- tftpd
 323          * ...
 324          */
 325         block_nr = 1;
 326         cp = xbuf + 2;
 327
 328         if (!ENABLE_TFTP || our_lsa) { /* tftpd */
 329                 /* Open file (must be after changing user) */
 330                 local_fd = open(local_file, open_mode, 0666);
 331                 if (local_fd < 0) {
 332                         error_pkt_reason = ERR_NOFILE;
 333                         strcpy((char*)error_pkt_str, "can't open file");
 334                         goto send_err_pkt;
 335                 }
 336 /* gcc 4.3.1 would NOT optimize it out as it should! */
 337 #if ENABLE_FEATURE_TFTP_BLOCKSIZE
 338                 if (blksize != TFTP_BLKSIZE_DEFAULT || want_transfer_size) {
 339                         /* Create and send OACK packet. */
 340                         /* For the download case, block_nr is still 1 -
 341                          * we expect 1st ACK from peer to be for (block_nr-1),
 342                          * that is, for "block 0" which is our OACK pkt */
 343                         opcode = TFTP_OACK;
 344                         goto add_blksize_opt;
 345                 }
 346 #endif
 347                 if (CMD_GET(option_mask32)) {
 348                         /* It's upload and we don't send OACK.
 349                          * We must ACK 1st packet (with filename)
 350                          * as if it is "block 0" */
 351                         block_nr = 0;
 352                 }
 353
 354         } else { /* tftp */
 355                 /* Open file (must be after changing user) */
 356                 local_fd = CMD_GET(option_mask32) ? STDOUT_FILENO : STDIN_FILENO;
 357                 if (NOT_LONE_DASH(local_file))
 358                         local_fd = xopen(local_file, open_mode);
 359 /* Removing #if, or using if() statement instead of #if may lead to
 360  * "warning: null argument where non-null required": */
 361 #if ENABLE_TFTP
 362                 /* tftp */
 363
 364                 /* We can't (and don't really need to) bind the socket:
 365                  * we don't know from which local IP datagrams will be sent,
 366                  * but kernel will pick the same IP every time (unless routing
 367                  * table is changed), thus peer will see dgrams consistently
 368                  * coming from the same IP.
 369                  * We would like to connect the socket, but since peer's
 370                  * UDP code can be less perfect than ours, _peer's_ IP:port
 371                  * in replies may differ from IP:port we used to send
 372                  * our first packet. We can connect() only when we get
 373                  * first reply. */
 374
 375                 /* build opcode */
 376                 opcode = TFTP_WRQ;
 377                 if (CMD_GET(option_mask32)) {
 378                         opcode = TFTP_RRQ;
 379                 }
 380                 /* add filename and mode */
 381                 /* fill in packet if the filename fits into xbuf */
 382                 len = strlen(remote_file) + 1;
 383                 if (2 + len + sizeof("octet") >= io_bufsize) {
 384                         bb_error_msg("remote filename is too long");
 385                         goto ret;
 386                 }
 387                 strcpy(cp, remote_file);
 388                 cp += len;
 389                 /* add "mode" part of the packet */
 390                 strcpy(cp, "octet");
 391                 cp += sizeof("octet");
 392
 393 # if ENABLE_FEATURE_TFTP_BLOCKSIZE
 394                 if (blksize == TFTP_BLKSIZE_DEFAULT && !want_transfer_size)
 395                         goto send_pkt;
 396
 397                 /* Need to add option to pkt */
 398                 if ((&xbuf[io_bufsize - 1] - cp) < sizeof("blksize NNNNN tsize ") + sizeof(off_t)*3) {
 399                         bb_error_msg("remote filename is too long");
 400                         goto ret;
 401                 }
 402                 expect_OACK = 1;
 403 # endif
 404 #endif /* ENABLE_TFTP */
 405
 406 #if ENABLE_FEATURE_TFTP_BLOCKSIZE
 407  add_blksize_opt:
 408                 if (blksize != TFTP_BLKSIZE_DEFAULT) {
 409                         /* add "blksize", <nul>, blksize, <nul> */
 410                         strcpy(cp, "blksize");
 411                         cp += sizeof("blksize");
 412                         cp += snprintf(cp, 6, "%d", blksize) + 1;
 413                 }
 414                 if (want_transfer_size) {
 415                         /* add "tsize", <nul>, size, <nul> (see RFC2349) */
 416                         /* if tftp and downloading, we send "0" (since we opened local_fd with O_TRUNC)
 417                          * and this makes server to send "tsize" option with the size */
 418                         /* if tftp and uploading, we send file size (maybe dont, to not confuse old servers???) */
 419                         /* if tftpd and downloading, we are answering to client's request */
 420                         /* if tftpd and uploading: !want_transfer_size, this code is not executed */
 421                         struct stat st;
 422                         strcpy(cp, "tsize");
 423                         cp += sizeof("tsize");
 424                         st.st_size = 0;
 425                         fstat(local_fd, &st);
 426                         cp += sprintf(cp, "%"OFF_FMT"u", (off_t)st.st_size) + 1;
 427 # if ENABLE_FEATURE_TFTP_PROGRESS_BAR
 428                         /* Save for progress bar. If 0 (tftp downloading),
 429                          * we look at server's reply later */
 430                         G.size = st.st_size;
 431                         if (remote_file && st.st_size)
 432                                 tftp_progress_init();
 433 # endif
 434                 }
 435 #endif
 436                 /* First packet is built, so skip packet generation */
 437                 goto send_pkt;
 438         }
 439
 440         /* Using mostly goto's - continue/break will be less clear
 441          * in where we actually jump to */
 442         while (1) {
 443                 /* Build ACK or DATA */
 444                 cp = xbuf + 2;
 445                 *((uint16_t*)cp) = htons(block_nr);
 446                 cp += 2;
 447                 block_nr++;
 448                 opcode = TFTP_ACK;
 449                 if (CMD_PUT(option_mask32)) {
 450                         opcode = TFTP_DATA;
 451                         len = full_read(local_fd, cp, blksize);
 452                         if (len < 0) {
 453                                 goto send_read_err_pkt;
 454                         }
 455                         if (len != blksize) {
 456                                 finished = 1;
 457                         }
 458                         cp += len;
 459                         IF_FEATURE_TFTP_PROGRESS_BAR(G.pos += len;)
 460                 }
 461  send_pkt:
 462                 /* Send packet */
 463                 *((uint16_t*)xbuf) = htons(opcode); /* fill in opcode part */
 464                 send_len = cp - xbuf;
 465                 /* NB: send_len value is preserved in code below
 466                  * for potential resend */
 467
 468                 retries = TFTP_NUM_RETRIES;  /* re-initialize */
 469                 waittime_ms = TFTP_TIMEOUT_MS;
 470
 471  send_again:
 472 #if ENABLE_TFTP_DEBUG
 473                 fprintf(stderr, "sending %u bytes\n", send_len);
 474                 for (cp = xbuf; cp < &xbuf[send_len]; cp++)
 475                         fprintf(stderr, "%02x ", (unsigned char) *cp);
 476                 fprintf(stderr, "\n");
 477 #endif
 478                 xsendto(socket_fd, xbuf, send_len, &peer_lsa->u.sa, peer_lsa->len);
 479
 480 #if ENABLE_FEATURE_TFTP_PROGRESS_BAR
 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                                 IF_FEATURE_TFTP_PROGRESS_BAR(G.pos += sz;)
 625                                 continue; /* send ACK */
 626                         }
 627 /* Disabled to cope with servers with Sorcerer's Apprentice Syndrome */
 628 #if 0
 629                         if (recv_blk == (block_nr - 1)) {
 630                                 /* Server lost our TFTP_ACK.  Resend it */
 631                                 block_nr = recv_blk;
 632                                 continue;
 633                         }
 634 #endif
 635                 }
 636
 637                 if (CMD_PUT(option_mask32) && (opcode == TFTP_ACK)) {
 638                         /* did peer ACK our last DATA pkt? */
 639                         if (recv_blk == (uint16_t) (block_nr - 1)) {
 640                                 if (finished)
 641                                         goto ret;
 642                                 continue; /* send next block */
 643                         }
 644                 }
 645                 /* Awww... recv'd packet is not recognized! */
 646                 goto recv_again;
 647                 /* why recv_again? - rfc1123 says:
 648                  * "The sender (i.e., the side originating the DATA packets)
 649                  *  must never resend the current DATA packet on receipt
 650                  *  of a duplicate ACK".
 651                  * DATA pkts are resent ONLY on timeout.
 652                  * Thus "goto send_again" will ba a bad mistake above.
 653                  * See:
 654                  * http://en.wikipedia.org/wiki/Sorcerer's_Apprentice_Syndrome
 655                  */
 656         } /* end of "while (1)" */
 657  ret:
 658         if (ENABLE_FEATURE_CLEAN_UP) {
 659                 close(local_fd);
 660                 close(socket_fd);
 661                 free(xbuf);
 662                 free(rbuf);
 663         }
 664         return finished == 0; /* returns 1 on failure */
 665
 666  send_read_err_pkt:
 667         strcpy((char*)error_pkt_str, bb_msg_read_error);
 668  send_err_pkt:
 669         if (error_pkt_str[0])
 670                 bb_error_msg("%s", (char*)error_pkt_str);
 671         error_pkt[1] = TFTP_ERROR;
 672         xsendto(socket_fd, error_pkt, 4 + 1 + strlen((char*)error_pkt_str),
 673                         &peer_lsa->u.sa, peer_lsa->len);
 674         return EXIT_FAILURE;
 675 #undef remote_file
 676 }
 677
 678 #if ENABLE_TFTP
 679
 680 int tftp_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 681 int tftp_main(int argc UNUSED_PARAM, char **argv)
 682 {
 683         len_and_sockaddr *peer_lsa;
 684         const char *local_file = NULL;
 685         const char *remote_file = NULL;
 686 # if ENABLE_FEATURE_TFTP_BLOCKSIZE
 687         const char *blksize_str = TFTP_BLKSIZE_DEFAULT_STR;
 688         int blksize;
 689 # endif
 690         int result;
 691         int port;
 692         IF_GETPUT(int opt;)
 693
 694         INIT_G();
 695
 696         /* -p or -g is mandatory, and they are mutually exclusive */
 697         opt_complementary = "" IF_FEATURE_TFTP_GET("g:") IF_FEATURE_TFTP_PUT("p:")
 698                         IF_GETPUT("g--p:p--g:");
 699
 700         IF_GETPUT(opt =) getopt32(argv,
 701                         IF_FEATURE_TFTP_GET("g") IF_FEATURE_TFTP_PUT("p")
 702                                 "l:r:" IF_FEATURE_TFTP_BLOCKSIZE("b:"),
 703                         &local_file, &remote_file
 704                         IF_FEATURE_TFTP_BLOCKSIZE(, &blksize_str));
 705         argv += optind;
 706
 707 # if ENABLE_FEATURE_TFTP_BLOCKSIZE
 708         /* Check if the blksize is valid:
 709          * RFC2348 says between 8 and 65464 */
 710         blksize = tftp_blksize_check(blksize_str, 65564);
 711         if (blksize < 0) {
 712                 //bb_error_msg("bad block size");
 713                 return EXIT_FAILURE;
 714         }
 715 # endif
 716
 717         if (remote_file) {
 718                 if (!local_file) {
 719                         const char *slash = strrchr(remote_file, '/');
 720                         local_file = slash ? slash + 1 : remote_file;
 721                 }
 722         } else {
 723                 remote_file = local_file;
 724         }
 725
 726         /* Error if filename or host is not known */
 727         if (!remote_file || !argv[0])
 728                 bb_show_usage();
 729
 730         port = bb_lookup_port(argv[1], "udp", 69);
 731         peer_lsa = xhost2sockaddr(argv[0], port);
 732
 733 # if ENABLE_TFTP_DEBUG
 734         fprintf(stderr, "using server '%s', remote_file '%s', local_file '%s'\n",
 735                         xmalloc_sockaddr2dotted(&peer_lsa->u.sa),
 736                         remote_file, local_file);
 737 # endif
 738
 739 # if ENABLE_FEATURE_TFTP_PROGRESS_BAR
 740         G.file = remote_file;
 741 # endif
 742         result = tftp_protocol(
 743                 NULL /*our_lsa*/, peer_lsa,
 744                 local_file, remote_file
 745                 IF_FEATURE_TFTP_BLOCKSIZE(, 1 /* want_transfer_size */)
 746                 IF_FEATURE_TFTP_BLOCKSIZE(, blksize)
 747         );
 748         tftp_progress_done();
 749
 750         if (result != EXIT_SUCCESS && NOT_LONE_DASH(local_file) && CMD_GET(opt)) {
 751                 unlink(local_file);
 752         }
 753         return result;
 754 }
 755
 756 #endif /* ENABLE_TFTP */
 757
 758 #if ENABLE_TFTPD
 759 int tftpd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 760 int tftpd_main(int argc UNUSED_PARAM, char **argv)
 761 {
 762         len_and_sockaddr *our_lsa;
 763         len_and_sockaddr *peer_lsa;
 764         char *local_file, *mode;
 765         const char *error_msg;
 766         int opt, result, opcode;
 767         IF_FEATURE_TFTP_BLOCKSIZE(int blksize = TFTP_BLKSIZE_DEFAULT;)
 768         IF_FEATURE_TFTP_BLOCKSIZE(int want_transfer_size = 0;)
 769
 770         INIT_G();
 771
 772         our_lsa = get_sock_lsa(STDIN_FILENO);
 773         if (!our_lsa) {
 774                 /* This is confusing:
 775                  *bb_error_msg_and_die("stdin is not a socket");
 776                  * Better: */
 777                 bb_show_usage();
 778                 /* Help text says that tftpd must be used as inetd service,
 779                  * which is by far the most usual cause of get_sock_lsa
 780                  * failure */
 781         }
 782         peer_lsa = xzalloc(LSA_LEN_SIZE + our_lsa->len);
 783         peer_lsa->len = our_lsa->len;
 784
 785         /* Shifting to not collide with TFTP_OPTs */
 786         opt = option_mask32 = TFTPD_OPT | (getopt32(argv, "rcu:l", &user_opt) << 8);
 787         argv += optind;
 788         if (opt & TFTPD_OPT_l) {
 789                 openlog(applet_name, LOG_PID, LOG_DAEMON);
 790                 logmode = LOGMODE_SYSLOG;
 791         }
 792         if (argv[0]) {
 793                 xchroot(argv[0]);
 794         }
 795
 796         result = recv_from_to(STDIN_FILENO, block_buf, sizeof(block_buf),
 797                         0 /* flags */,
 798                         &peer_lsa->u.sa, &our_lsa->u.sa, our_lsa->len);
 799
 800         error_msg = "malformed packet";
 801         opcode = ntohs(*(uint16_t*)block_buf);
 802         if (result < 4 || result >= sizeof(block_buf)
 803          || block_buf[result-1] != '\0'
 804          || (IF_FEATURE_TFTP_PUT(opcode != TFTP_RRQ) /* not download */
 805              IF_GETPUT(&&)
 806              IF_FEATURE_TFTP_GET(opcode != TFTP_WRQ) /* not upload */
 807             )
 808         ) {
 809                 goto err;
 810         }
 811         local_file = block_buf + 2;
 812         if (local_file[0] == '.' || strstr(local_file, "/.")) {
 813                 error_msg = "dot in file name";
 814                 goto err;
 815         }
 816         mode = local_file + strlen(local_file) + 1;
 817         /* RFC 1350 says mode string is case independent */
 818         if (mode >= block_buf + result || strcasecmp(mode, "octet") != 0) {
 819                 goto err;
 820         }
 821 # if ENABLE_FEATURE_TFTP_BLOCKSIZE
 822         {
 823                 char *res;
 824                 char *opt_str = mode + sizeof("octet");
 825                 int opt_len = block_buf + result - opt_str;
 826                 if (opt_len > 0) {
 827                         res = tftp_get_option("blksize", opt_str, opt_len);
 828                         if (res) {
 829                                 blksize = tftp_blksize_check(res, 65564);
 830                                 if (blksize < 0) {
 831                                         error_pkt_reason = ERR_BAD_OPT;
 832                                         /* will just send error pkt */
 833                                         goto do_proto;
 834                                 }
 835                         }
 836                         if (opcode != TFTP_WRQ /* download? */
 837                         /* did client ask us about file size? */
 838                          && tftp_get_option("tsize", opt_str, opt_len)
 839                         ) {
 840                                 want_transfer_size = 1;
 841                         }
 842                 }
 843         }
 844 # endif
 845
 846         if (!ENABLE_FEATURE_TFTP_PUT || opcode == TFTP_WRQ) {
 847                 if (opt & TFTPD_OPT_r) {
 848                         /* This would mean "disk full" - not true */
 849                         /*error_pkt_reason = ERR_WRITE;*/
 850                         error_msg = bb_msg_write_error;
 851                         goto err;
 852                 }
 853                 IF_GETPUT(option_mask32 |= TFTP_OPT_GET;) /* will receive file's data */
 854         } else {
 855                 IF_GETPUT(option_mask32 |= TFTP_OPT_PUT;) /* will send file's data */
 856         }
 857
 858         /* NB: if error_pkt_str or error_pkt_reason is set up,
 859          * tftp_protocol() just sends one error pkt and returns */
 860
 861  do_proto:
 862         close(STDIN_FILENO); /* close old, possibly wildcard socket */
 863         /* tftp_protocol() will create new one, bound to particular local IP */
 864         result = tftp_protocol(
 865                 our_lsa, peer_lsa,
 866                 local_file IF_TFTP(, NULL /*remote_file*/)
 867                 IF_FEATURE_TFTP_BLOCKSIZE(, want_transfer_size)
 868                 IF_FEATURE_TFTP_BLOCKSIZE(, blksize)
 869         );
 870
 871         return result;
 872  err:
 873         strcpy((char*)error_pkt_str, error_msg);
 874         goto do_proto;
 875 }
 876
 877 #endif /* ENABLE_TFTPD */
 878
 879 #endif /* ENABLE_FEATURE_TFTP_GET || ENABLE_FEATURE_TFTP_PUT */