release/src/router/busybox/networking/tftp.c

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