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 "common_bufsiz.h"
  55 #include <syslog.h>
  56
  57 #if ENABLE_FEATURE_TFTP_GET || ENABLE_FEATURE_TFTP_PUT
  58
  59 #define TFTP_BLKSIZE_DEFAULT       512  /* according to RFC 1350, don't change */
  60 #define TFTP_BLKSIZE_DEFAULT_STR "512"
  61 /* Was 50 ms but users asked to bump it up a bit */
  62 #define TFTP_TIMEOUT_MS            100
  63 #define TFTP_MAXTIMEOUT_MS        2000
  64 #define TFTP_NUM_RETRIES            12  /* number of backed-off retries */
  65
  66 /* opcodes we support */
  67 #define TFTP_RRQ   1
  68 #define TFTP_WRQ   2
  69 #define TFTP_DATA  3
  70 #define TFTP_ACK   4
  71 #define TFTP_ERROR 5
  72 #define TFTP_OACK  6
  73
  74 /* error codes sent over network (we use only 0, 1, 3 and 8) */
  75 /* generic (error message is included in the packet) */
  76 #define ERR_UNSPEC   0
  77 #define ERR_NOFILE   1
  78 #define ERR_ACCESS   2
  79 /* disk full or allocation exceeded */
  80 #define ERR_WRITE    3
  81 #define ERR_OP       4
  82 #define ERR_BAD_ID   5
  83 #define ERR_EXIST    6
  84 #define ERR_BAD_USER 7
  85 #define ERR_BAD_OPT  8
  86
  87 /* masks coming from getopt32 */
  88 enum {
  89         TFTP_OPT_GET = (1 << 0),
  90         TFTP_OPT_PUT = (1 << 1),
  91         /* pseudo option: if set, it's tftpd */
  92         TFTPD_OPT = (1 << 7) * ENABLE_TFTPD,
  93         TFTPD_OPT_r = (1 << 8) * ENABLE_TFTPD,
  94         TFTPD_OPT_c = (1 << 9) * ENABLE_TFTPD,
  95         TFTPD_OPT_u = (1 << 10) * ENABLE_TFTPD,
  96         TFTPD_OPT_l = (1 << 11) * ENABLE_TFTPD,
  97 };
  98
  99 #if ENABLE_FEATURE_TFTP_GET && !ENABLE_FEATURE_TFTP_PUT
 100 #define IF_GETPUT(...)
 101 #define CMD_GET(cmd) 1
 102 #define CMD_PUT(cmd) 0
 103 #elif !ENABLE_FEATURE_TFTP_GET && ENABLE_FEATURE_TFTP_PUT
 104 #define IF_GETPUT(...)
 105 #define CMD_GET(cmd) 0
 106 #define CMD_PUT(cmd) 1
 107 #else
 108 #define IF_GETPUT(...) __VA_ARGS__
 109 #define CMD_GET(cmd) ((cmd) & TFTP_OPT_GET)
 110 #define CMD_PUT(cmd) ((cmd) & TFTP_OPT_PUT)
 111 #endif
 112 /* NB: in the code below
 113  * CMD_GET(cmd) and CMD_PUT(cmd) are mutually exclusive
 114  */
 115
 116
 117 struct globals {
 118         /* u16 TFTP_ERROR; u16 reason; both network-endian, then error text: */
 119         uint8_t error_pkt[4 + 32];
 120         struct passwd *pw;
 121         /* Used in tftpd_main() for initial packet */
 122         /* Some HP PA-RISC firmware always sends fixed 516-byte requests */
 123         char block_buf[516];
 124         char block_buf_tail[1];
 125 #if ENABLE_FEATURE_TFTP_PROGRESS_BAR
 126         off_t pos;
 127         off_t size;
 128         const char *file;
 129         bb_progress_t pmt;
 130 #endif
 131 } FIX_ALIASING;
 132 #define G (*(struct globals*)bb_common_bufsiz1)
 133 #define INIT_G() do { \
 134         setup_common_bufsiz(); \
 135         BUILD_BUG_ON(sizeof(G) > COMMON_BUFSIZE); \
 136 } while (0)
 137
 138 #define G_error_pkt_reason (G.error_pkt[3])
 139 #define G_error_pkt_str    ((char*)(G.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 (G_error_pkt_reason || G_error_pkt_str[0])
 276                         goto send_err_pkt;
 277
 278                 if (G.pw) {
 279                         change_identity(G.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                         G_error_pkt_reason = ERR_NOFILE;
 332                         strcpy(G_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         } else { /* tftp */
 353                 /* Open file (must be after changing user) */
 354                 local_fd = CMD_GET(option_mask32) ? STDOUT_FILENO : STDIN_FILENO;
 355                 if (NOT_LONE_DASH(local_file))
 356                         local_fd = xopen(local_file, open_mode);
 357 /* Removing #if, or using if() statement instead of #if may lead to
 358  * "warning: null argument where non-null required": */
 359 #if ENABLE_TFTP
 360                 /* tftp */
 361
 362                 /* We can't (and don't really need to) bind the socket:
 363                  * we don't know from which local IP datagrams will be sent,
 364                  * but kernel will pick the same IP every time (unless routing
 365                  * table is changed), thus peer will see dgrams consistently
 366                  * coming from the same IP.
 367                  * We would like to connect the socket, but since peer's
 368                  * UDP code can be less perfect than ours, _peer's_ IP:port
 369                  * in replies may differ from IP:port we used to send
 370                  * our first packet. We can connect() only when we get
 371                  * first reply. */
 372
 373                 /* build opcode */
 374                 opcode = TFTP_WRQ;
 375                 if (CMD_GET(option_mask32)) {
 376                         opcode = TFTP_RRQ;
 377                 }
 378                 /* add filename and mode */
 379                 /* fill in packet if the filename fits into xbuf */
 380                 len = strlen(remote_file) + 1;
 381                 if (2 + len + sizeof("octet") >= io_bufsize) {
 382                         bb_error_msg("remote filename is too long");
 383                         goto ret;
 384                 }
 385                 strcpy(cp, remote_file);
 386                 cp += len;
 387                 /* add "mode" part of the packet */
 388                 strcpy(cp, "octet");
 389                 cp += sizeof("octet");
 390
 391 # if ENABLE_FEATURE_TFTP_BLOCKSIZE
 392                 if (blksize == TFTP_BLKSIZE_DEFAULT && !want_transfer_size)
 393                         goto send_pkt;
 394
 395                 /* Need to add option to pkt */
 396                 if ((&xbuf[io_bufsize - 1] - cp) < sizeof("blksize NNNNN tsize ") + sizeof(off_t)*3) {
 397                         bb_error_msg("remote filename is too long");
 398                         goto ret;
 399                 }
 400                 expect_OACK = 1;
 401 # endif
 402 #endif /* ENABLE_TFTP */
 403
 404 #if ENABLE_FEATURE_TFTP_BLOCKSIZE
 405  add_blksize_opt:
 406                 if (blksize != TFTP_BLKSIZE_DEFAULT) {
 407                         /* add "blksize", <nul>, blksize, <nul> */
 408                         strcpy(cp, "blksize");
 409                         cp += sizeof("blksize");
 410                         cp += snprintf(cp, 6, "%d", blksize) + 1;
 411                 }
 412                 if (want_transfer_size) {
 413                         /* add "tsize", <nul>, size, <nul> (see RFC2349) */
 414                         /* if tftp and downloading, we send "0" (since we opened local_fd with O_TRUNC)
 415                          * and this makes server to send "tsize" option with the size */
 416                         /* if tftp and uploading, we send file size (maybe dont, to not confuse old servers???) */
 417                         /* if tftpd and downloading, we are answering to client's request */
 418                         /* if tftpd and uploading: !want_transfer_size, this code is not executed */
 419                         struct stat st;
 420                         strcpy(cp, "tsize");
 421                         cp += sizeof("tsize");
 422                         st.st_size = 0;
 423                         fstat(local_fd, &st);
 424                         cp += sprintf(cp, "%"OFF_FMT"u", (off_t)st.st_size) + 1;
 425 # if ENABLE_FEATURE_TFTP_PROGRESS_BAR
 426                         /* Save for progress bar. If 0 (tftp downloading),
 427                          * we look at server's reply later */
 428                         G.size = st.st_size;
 429                         if (remote_file && st.st_size)
 430                                 tftp_progress_init();
 431 # endif
 432                 }
 433 #endif
 434                 /* First packet is built, so skip packet generation */
 435                 goto send_pkt;
 436         }
 437
 438         /* Using mostly goto's - continue/break will be less clear
 439          * in where we actually jump to */
 440         while (1) {
 441                 /* Build ACK or DATA */
 442                 cp = xbuf + 2;
 443                 *((uint16_t*)cp) = htons(block_nr);
 444                 cp += 2;
 445                 block_nr++;
 446                 opcode = TFTP_ACK;
 447                 if (CMD_PUT(option_mask32)) {
 448                         opcode = TFTP_DATA;
 449                         len = full_read(local_fd, cp, blksize);
 450                         if (len < 0) {
 451                                 goto send_read_err_pkt;
 452                         }
 453                         if (len != blksize) {
 454                                 finished = 1;
 455                         }
 456                         cp += len;
 457                         IF_FEATURE_TFTP_PROGRESS_BAR(G.pos += 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 (is_bb_progress_inited(&G.pmt))
 480                         tftp_progress_update();
 481 #endif
 482                 /* Was it final ACK? then exit */
 483                 if (finished && (opcode == TFTP_ACK))
 484                         goto ret;
 485
 486  recv_again:
 487                 /* Receive packet */
 488                 /*pfd[0].fd = socket_fd;*/
 489                 pfd[0].events = POLLIN;
 490                 switch (safe_poll(pfd, 1, waittime_ms)) {
 491                 default:
 492                         /*bb_perror_msg("poll"); - done in safe_poll */
 493                         goto ret;
 494                 case 0:
 495                         retries--;
 496                         if (retries == 0) {
 497                                 tftp_progress_done();
 498                                 bb_error_msg("timeout");
 499                                 goto ret; /* no err packet sent */
 500                         }
 501
 502                         /* exponential backoff with limit */
 503                         waittime_ms += waittime_ms/2;
 504                         if (waittime_ms > TFTP_MAXTIMEOUT_MS) {
 505                                 waittime_ms = TFTP_MAXTIMEOUT_MS;
 506                         }
 507
 508                         goto send_again; /* resend last sent pkt */
 509                 case 1:
 510                         if (!our_lsa) {
 511                                 /* tftp (not tftpd!) receiving 1st packet */
 512                                 our_lsa = ((void*)(ptrdiff_t)-1); /* not NULL */
 513                                 len = recvfrom(socket_fd, rbuf, io_bufsize, 0,
 514                                                 &peer_lsa->u.sa, &peer_lsa->len);
 515                                 /* Our first dgram went to port 69
 516                                  * but reply may come from different one.
 517                                  * Remember and use this new port (and IP) */
 518                                 if (len >= 0)
 519                                         xconnect(socket_fd, &peer_lsa->u.sa, peer_lsa->len);
 520                         } else {
 521                                 /* tftpd, or not the very first packet:
 522                                  * socket is connect()ed, can just read from it. */
 523                                 /* Don't full_read()!
 524                                  * This is not TCP, one read == one pkt! */
 525                                 len = safe_read(socket_fd, rbuf, io_bufsize);
 526                         }
 527                         if (len < 0) {
 528                                 goto send_read_err_pkt;
 529                         }
 530                         if (len < 4) { /* too small? */
 531                                 goto recv_again;
 532                         }
 533                 }
 534
 535                 /* Process recv'ed packet */
 536                 opcode = ntohs( ((uint16_t*)rbuf)[0] );
 537                 recv_blk = ntohs( ((uint16_t*)rbuf)[1] );
 538 #if ENABLE_TFTP_DEBUG
 539                 fprintf(stderr, "received %d bytes: %04x %04x\n", len, opcode, recv_blk);
 540 #endif
 541                 if (opcode == TFTP_ERROR) {
 542                         static const char errcode_str[] ALIGN1 =
 543                                 "\0"
 544                                 "file not found\0"
 545                                 "access violation\0"
 546                                 "disk full\0"
 547                                 "bad operation\0"
 548                                 "unknown transfer id\0"
 549                                 "file already exists\0"
 550                                 "no such user\0"
 551                                 "bad option";
 552
 553                         const char *msg = "";
 554
 555                         if (len > 4 && rbuf[4] != '\0') {
 556                                 msg = &rbuf[4];
 557                                 rbuf[io_bufsize - 1] = '\0'; /* paranoia */
 558                         } else if (recv_blk <= 8) {
 559                                 msg = nth_string(errcode_str, recv_blk);
 560                         }
 561                         bb_error_msg("server error: (%u) %s", recv_blk, msg);
 562                         goto ret;
 563                 }
 564
 565 #if ENABLE_FEATURE_TFTP_BLOCKSIZE
 566                 if (expect_OACK) {
 567                         expect_OACK = 0;
 568                         if (opcode == TFTP_OACK) {
 569                                 /* server seems to support options */
 570                                 char *res;
 571
 572                                 res = tftp_get_option("blksize", &rbuf[2], len - 2);
 573                                 if (res) {
 574                                         blksize = tftp_blksize_check(res, blksize);
 575                                         if (blksize < 0) {
 576                                                 G_error_pkt_reason = ERR_BAD_OPT;
 577                                                 goto send_err_pkt;
 578                                         }
 579                                         io_bufsize = blksize + 4;
 580                                 }
 581 # if ENABLE_FEATURE_TFTP_PROGRESS_BAR
 582                                 if (remote_file && G.size == 0) { /* if we don't know it yet */
 583                                         res = tftp_get_option("tsize", &rbuf[2], len - 2);
 584                                         if (res) {
 585                                                 G.size = bb_strtoull(res, NULL, 10);
 586                                                 if (G.size)
 587                                                         tftp_progress_init();
 588                                         }
 589                                 }
 590 # endif
 591                                 if (CMD_GET(option_mask32)) {
 592                                         /* We'll send ACK for OACK,
 593                                          * such ACK has "block no" of 0 */
 594                                         block_nr = 0;
 595                                 }
 596                                 continue;
 597                         }
 598                         /* rfc2347:
 599                          * "An option not acknowledged by the server
 600                          * must be ignored by the client and server
 601                          * as if it were never requested." */
 602                         if (blksize != TFTP_BLKSIZE_DEFAULT)
 603                                 bb_error_msg("falling back to blocksize "TFTP_BLKSIZE_DEFAULT_STR);
 604                         blksize = TFTP_BLKSIZE_DEFAULT;
 605                         io_bufsize = TFTP_BLKSIZE_DEFAULT + 4;
 606                 }
 607 #endif
 608                 /* block_nr is already advanced to next block# we expect
 609                  * to get / block# we are about to send next time */
 610
 611                 if (CMD_GET(option_mask32) && (opcode == TFTP_DATA)) {
 612                         if (recv_blk == block_nr) {
 613                                 int sz = full_write(local_fd, &rbuf[4], len - 4);
 614                                 if (sz != len - 4) {
 615                                         strcpy(G_error_pkt_str, bb_msg_write_error);
 616                                         G_error_pkt_reason = ERR_WRITE;
 617                                         goto send_err_pkt;
 618                                 }
 619                                 if (sz != blksize) {
 620                                         finished = 1;
 621                                 }
 622                                 IF_FEATURE_TFTP_PROGRESS_BAR(G.pos += sz;)
 623                                 continue; /* send ACK */
 624                         }
 625 /* Disabled to cope with servers with Sorcerer's Apprentice Syndrome */
 626 #if 0
 627                         if (recv_blk == (block_nr - 1)) {
 628                                 /* Server lost our TFTP_ACK.  Resend it */
 629                                 block_nr = recv_blk;
 630                                 continue;
 631                         }
 632 #endif
 633                 }
 634
 635                 if (CMD_PUT(option_mask32) && (opcode == TFTP_ACK)) {
 636                         /* did peer ACK our last DATA pkt? */
 637                         if (recv_blk == (uint16_t) (block_nr - 1)) {
 638                                 if (finished)
 639                                         goto ret;
 640                                 continue; /* send next block */
 641                         }
 642                 }
 643                 /* Awww... recv'd packet is not recognized! */
 644                 goto recv_again;
 645                 /* why recv_again? - rfc1123 says:
 646                  * "The sender (i.e., the side originating the DATA packets)
 647                  *  must never resend the current DATA packet on receipt
 648                  *  of a duplicate ACK".
 649                  * DATA pkts are resent ONLY on timeout.
 650                  * Thus "goto send_again" will ba a bad mistake above.
 651                  * See:
 652                  * http://en.wikipedia.org/wiki/Sorcerer's_Apprentice_Syndrome
 653                  */
 654         } /* end of "while (1)" */
 655  ret:
 656         if (ENABLE_FEATURE_CLEAN_UP) {
 657                 close(local_fd);
 658                 close(socket_fd);
 659                 free(xbuf);
 660                 free(rbuf);
 661         }
 662         return finished == 0; /* returns 1 on failure */
 663
 664  send_read_err_pkt:
 665         strcpy(G_error_pkt_str, bb_msg_read_error);
 666  send_err_pkt:
 667         if (G_error_pkt_str[0])
 668                 bb_error_msg("%s", G_error_pkt_str);
 669         G.error_pkt[1] = TFTP_ERROR;
 670         xsendto(socket_fd, G.error_pkt, 4 + 1 + strlen(G_error_pkt_str),
 671                         &peer_lsa->u.sa, peer_lsa->len);
 672         return EXIT_FAILURE;
 673 #undef remote_file
 674 }
 675
 676 #if ENABLE_TFTP
 677
 678 int tftp_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 679 int tftp_main(int argc UNUSED_PARAM, char **argv)
 680 {
 681         len_and_sockaddr *peer_lsa;
 682         const char *local_file = NULL;
 683         const char *remote_file = NULL;
 684 # if ENABLE_FEATURE_TFTP_BLOCKSIZE
 685         const char *blksize_str = TFTP_BLKSIZE_DEFAULT_STR;
 686         int blksize;
 687 # endif
 688         int result;
 689         int port;
 690         IF_GETPUT(int opt;)
 691
 692         INIT_G();
 693
 694         /* -p or -g is mandatory, and they are mutually exclusive */
 695         opt_complementary = "" IF_FEATURE_TFTP_GET("g:") IF_FEATURE_TFTP_PUT("p:")
 696                         IF_GETPUT("g--p:p--g:");
 697
 698         IF_GETPUT(opt =) getopt32(argv,
 699                         IF_FEATURE_TFTP_GET("g") IF_FEATURE_TFTP_PUT("p")
 700                                 "l:r:" IF_FEATURE_TFTP_BLOCKSIZE("b:"),
 701                         &local_file, &remote_file
 702                         IF_FEATURE_TFTP_BLOCKSIZE(, &blksize_str));
 703         argv += optind;
 704
 705 # if ENABLE_FEATURE_TFTP_BLOCKSIZE
 706         /* Check if the blksize is valid:
 707          * RFC2348 says between 8 and 65464 */
 708         blksize = tftp_blksize_check(blksize_str, 65564);
 709         if (blksize < 0) {
 710                 //bb_error_msg("bad block size");
 711                 return EXIT_FAILURE;
 712         }
 713 # endif
 714
 715         if (remote_file) {
 716                 if (!local_file) {
 717                         const char *slash = strrchr(remote_file, '/');
 718                         local_file = slash ? slash + 1 : remote_file;
 719                 }
 720         } else {
 721                 remote_file = local_file;
 722         }
 723
 724         /* Error if filename or host is not known */
 725         if (!remote_file || !argv[0])
 726                 bb_show_usage();
 727
 728         port = bb_lookup_port(argv[1], "udp", 69);
 729         peer_lsa = xhost2sockaddr(argv[0], port);
 730
 731 # if ENABLE_TFTP_DEBUG
 732         fprintf(stderr, "using server '%s', remote_file '%s', local_file '%s'\n",
 733                         xmalloc_sockaddr2dotted(&peer_lsa->u.sa),
 734                         remote_file, local_file);
 735 # endif
 736
 737 # if ENABLE_FEATURE_TFTP_PROGRESS_BAR
 738         G.file = remote_file;
 739 # endif
 740         result = tftp_protocol(
 741                 NULL /*our_lsa*/, peer_lsa,
 742                 local_file, remote_file
 743                 IF_FEATURE_TFTP_BLOCKSIZE(, 1 /* want_transfer_size */)
 744                 IF_FEATURE_TFTP_BLOCKSIZE(, blksize)
 745         );
 746         tftp_progress_done();
 747
 748         if (result != EXIT_SUCCESS && NOT_LONE_DASH(local_file) && CMD_GET(opt)) {
 749                 unlink(local_file);
 750         }
 751         return result;
 752 }
 753
 754 #endif /* ENABLE_TFTP */
 755
 756 #if ENABLE_TFTPD
 757 int tftpd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 758 int tftpd_main(int argc UNUSED_PARAM, char **argv)
 759 {
 760         len_and_sockaddr *our_lsa;
 761         len_and_sockaddr *peer_lsa;
 762         char *mode, *user_opt;
 763         char *local_file = local_file;
 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:l", &user_opt) << 8);
 786         argv += optind;
 787         if (opt & TFTPD_OPT_l) {
 788                 openlog(applet_name, LOG_PID, LOG_DAEMON);
 789                 logmode = LOGMODE_SYSLOG;
 790         }
 791         if (opt & TFTPD_OPT_u) {
 792                 /* Must be before xchroot */
 793                 G.pw = xgetpwnam(user_opt);
 794         }
 795         if (argv[0]) {
 796                 xchroot(argv[0]);
 797         }
 798
 799         result = recv_from_to(STDIN_FILENO,
 800                         G.block_buf, sizeof(G.block_buf) + 1,
 801                         /* ^^^ sizeof+1 to reliably detect oversized input */
 802                         0 /* flags */,
 803                         &peer_lsa->u.sa, &our_lsa->u.sa, our_lsa->len);
 804
 805         error_msg = "malformed packet";
 806         opcode = ntohs(*(uint16_t*)G.block_buf);
 807         if (result < 4 || result > sizeof(G.block_buf)
 808         /*|| G.block_buf[result-1] != '\0' - bug compatibility, see below */
 809          || (IF_FEATURE_TFTP_PUT(opcode != TFTP_RRQ) /* not download */
 810              IF_GETPUT(&&)
 811              IF_FEATURE_TFTP_GET(opcode != TFTP_WRQ) /* not upload */
 812             )
 813         ) {
 814                 goto err;
 815         }
 816         /* Some HP PA-RISC firmware always sends fixed 516-byte requests,
 817          * with trailing garbage.
 818          * Support that by not requiring NUL to be the last byte (see above).
 819          * To make strXYZ() ops safe, force NUL termination:
 820          */
 821         G.block_buf_tail[0] = '\0';
 822
 823         local_file = G.block_buf + 2;
 824         if (local_file[0] == '.' || strstr(local_file, "/.")) {
 825                 error_msg = "dot in file name";
 826                 goto err;
 827         }
 828         mode = local_file + strlen(local_file) + 1;
 829         /* RFC 1350 says mode string is case independent */
 830         if (mode >= G.block_buf + result || strcasecmp(mode, "octet") != 0) {
 831                 goto err;
 832         }
 833 # if ENABLE_FEATURE_TFTP_BLOCKSIZE
 834         {
 835                 char *res;
 836                 char *opt_str = mode + sizeof("octet");
 837                 int opt_len = G.block_buf + result - opt_str;
 838                 if (opt_len > 0) {
 839                         res = tftp_get_option("blksize", opt_str, opt_len);
 840                         if (res) {
 841                                 blksize = tftp_blksize_check(res, 65564);
 842                                 if (blksize < 0) {
 843                                         G_error_pkt_reason = ERR_BAD_OPT;
 844                                         /* will just send error pkt */
 845                                         goto do_proto;
 846                                 }
 847                         }
 848                         if (opcode != TFTP_WRQ /* download? */
 849                         /* did client ask us about file size? */
 850                          && tftp_get_option("tsize", opt_str, opt_len)
 851                         ) {
 852                                 want_transfer_size = 1;
 853                         }
 854                 }
 855         }
 856 # endif
 857
 858         if (!ENABLE_FEATURE_TFTP_PUT || opcode == TFTP_WRQ) {
 859                 if (opt & TFTPD_OPT_r) {
 860                         /* This would mean "disk full" - not true */
 861                         /*G_error_pkt_reason = ERR_WRITE;*/
 862                         error_msg = bb_msg_write_error;
 863                         goto err;
 864                 }
 865                 IF_GETPUT(option_mask32 |= TFTP_OPT_GET;) /* will receive file's data */
 866         } else {
 867                 IF_GETPUT(option_mask32 |= TFTP_OPT_PUT;) /* will send file's data */
 868         }
 869
 870         /* NB: if G_error_pkt_str or G_error_pkt_reason is set up,
 871          * tftp_protocol() just sends one error pkt and returns */
 872
 873  do_proto:
 874         close(STDIN_FILENO); /* close old, possibly wildcard socket */
 875         /* tftp_protocol() will create new one, bound to particular local IP */
 876         result = tftp_protocol(
 877                 our_lsa, peer_lsa,
 878                 local_file IF_TFTP(, NULL /*remote_file*/)
 879                 IF_FEATURE_TFTP_BLOCKSIZE(, want_transfer_size)
 880                 IF_FEATURE_TFTP_BLOCKSIZE(, blksize)
 881         );
 882
 883         return result;
 884  err:
 885         strcpy(G_error_pkt_str, error_msg);
 886         goto do_proto;
 887 }
 888
 889 #endif /* ENABLE_TFTPD */
 890
 891 #endif /* ENABLE_FEATURE_TFTP_GET || ENABLE_FEATURE_TFTP_PUT */