1 /* vi: set sw=4 ts=4: */
2 /* -------------------------------------------------------------------------
5 * A simple tftp client/server for busybox.
6 * Tries to follow RFC1350.
7 * Only "octet" mode supported.
8 * Optional blocksize negotiation (RFC2347 + RFC2348)
10 * Copyright (C) 2001 Magnus Damm <damm@opensource.se>
12 * Parts of the code based on:
14 * atftp: Copyright (C) 2000 Jean-Pierre Lefebvre <helix@step.polymtl.ca>
15 * and Remi Lefebvre <remi@debian.org>
17 * utftp: Copyright (C) 1999 Uwe Ohse <uwe@ohse.de>
19 * tftpd added by Denys Vlasenko & Vladimir Dronnikov
21 * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
22 * ------------------------------------------------------------------------- */
26 #if ENABLE_FEATURE_TFTP_GET || ENABLE_FEATURE_TFTP_PUT
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 */
34 /* opcodes we support */
42 /* error codes sent over network (we use only 0, 1, 3 and 8) */
43 /* generic (error message is included in the packet) */
47 /* disk full or allocation exceeded */
52 #define ERR_BAD_USER 7
55 /* masks coming from getopt32 */
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,
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
75 #define USE_GETPUT(...) __VA_ARGS__
76 #define CMD_GET(cmd) ((cmd) & TFTP_OPT_GET)
77 #define CMD_PUT(cmd) ((cmd) & TFTP_OPT_PUT)
79 /* NB: in the code below
80 * CMD_GET(cmd) and CMD_PUT(cmd) are mutually exclusive
85 /* u16 TFTP_ERROR; u16 reason; both network-endian, then error text: */
86 uint8_t error_pkt[4 + 32];
88 /* used in tftpd_main(), a bit big for stack: */
89 char block_buf[TFTP_BLKSIZE_DEFAULT];
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 )
99 #define error_pkt_reason (error_pkt[3])
100 #define error_pkt_str (error_pkt + 4)
103 #if ENABLE_FEATURE_TFTP_BLOCKSIZE
105 static int tftp_blksize_check(const char *blksize_str, int maxsize)
107 /* Check if the blksize is valid:
108 * RFC2348 says between 8 and 65464,
109 * but our implementation makes it impossible
110 * to use blksizes smaller than 22 octets. */
111 unsigned blksize = bb_strtou(blksize_str, NULL, 10);
113 || (blksize < 24) || (blksize > maxsize)
115 bb_error_msg("bad blocksize '%s'", blksize_str);
118 #if ENABLE_DEBUG_TFTP
119 bb_error_msg("using blksize %u", blksize);
124 static char *tftp_get_option(const char *option, char *buf, int len)
131 * "opt_name<NUL>opt_val<NUL>opt_name2<NUL>opt_val2<NUL>..." */
134 /* Make sure options are terminated correctly */
135 for (k = 0; k < len; k++) {
136 if (buf[k] == '\0') {
142 if (opt_val == 0) { /* it's "name" part */
143 if (strcasecmp(buf, option) == 0) {
146 } else if (opt_found) {
161 static int tftp_protocol(
162 len_and_sockaddr *our_lsa,
163 len_and_sockaddr *peer_lsa,
164 const char *local_file
165 USE_TFTP(, const char *remote_file)
166 USE_FEATURE_TFTP_BLOCKSIZE(USE_TFTPD(, void *tsize))
167 USE_FEATURE_TFTP_BLOCKSIZE(, int blksize))
170 #define remote_file NULL
172 #if !(ENABLE_FEATURE_TFTP_BLOCKSIZE && ENABLE_TFTPD)
175 #if !ENABLE_FEATURE_TFTP_BLOCKSIZE
176 enum { blksize = TFTP_BLKSIZE_DEFAULT };
179 struct pollfd pfd[1];
180 #define socket_fd (pfd[0].fd)
183 USE_FEATURE_TFTP_BLOCKSIZE(smallint want_option_ack = 0;)
184 smallint finished = 0;
188 int open_mode, local_fd;
189 int retries, waittime_ms;
190 int io_bufsize = blksize + 4;
192 /* Can't use RESERVE_CONFIG_BUFFER here since the allocation
193 * size varies meaning BUFFERS_GO_ON_STACK would fail */
194 /* We must keep the transmit and receive buffers seperate */
195 /* In case we rcv a garbage pkt and we need to rexmit the last pkt */
196 char *xbuf = xmalloc(io_bufsize);
197 char *rbuf = xmalloc(io_bufsize);
199 socket_fd = xsocket(peer_lsa->u.sa.sa_family, SOCK_DGRAM, 0);
200 setsockopt_reuseaddr(socket_fd);
205 if (!ENABLE_TFTP || our_lsa) {
208 /* Create a socket which is:
209 * 1. bound to IP:port peer sent 1st datagram to,
210 * 2. connected to peer's IP:port
211 * This way we will answer from the IP:port peer
212 * expects, will not get any other packets on
213 * the socket, and also plain read/write will work. */
214 xbind(socket_fd, &our_lsa->u.sa, our_lsa->len);
215 xconnect(socket_fd, &peer_lsa->u.sa, peer_lsa->len);
217 /* Is there an error already? Send pkt and bail out */
218 if (error_pkt_reason || error_pkt_str[0])
221 if (CMD_GET(option_mask32)) {
222 /* it's upload - we must ACK 1st packet (with filename)
223 * as if it's "block 0" */
228 struct passwd *pw = getpwnam(user_opt);
230 bb_error_msg_and_die("unknown user '%s'", user_opt);
231 change_identity(pw); /* initgroups, setgid, setuid */
235 /* Open local file (must be after changing user) */
236 if (CMD_PUT(option_mask32)) {
237 open_mode = O_RDONLY;
239 open_mode = O_WRONLY | O_TRUNC | O_CREAT;
241 if ((option_mask32 & (TFTPD_OPT+TFTPD_OPT_c)) == TFTPD_OPT) {
242 /* tftpd without -c */
243 open_mode = O_WRONLY | O_TRUNC;
247 if (!(option_mask32 & TFTPD_OPT)) {
248 local_fd = CMD_GET(option_mask32) ? STDOUT_FILENO : STDIN_FILENO;
249 if (NOT_LONE_DASH(local_file))
250 local_fd = xopen(local_file, open_mode);
252 local_fd = open(local_file, open_mode);
254 error_pkt_reason = ERR_NOFILE;
255 strcpy((char*)error_pkt_str, "can't open file");
260 if (!ENABLE_TFTP || our_lsa) {
261 /* gcc 4.3.1 would NOT optimize it out as it should! */
262 #if ENABLE_FEATURE_TFTP_BLOCKSIZE
263 if (blksize != TFTP_BLKSIZE_DEFAULT || tsize) {
264 /* Create and send OACK packet. */
265 /* For the download case, block_nr is still 1 -
266 * we expect 1st ACK from peer to be for (block_nr-1),
267 * that is, for "block 0" which is our OACK pkt */
269 goto add_blksize_opt;
273 /* Removing it, or using if() statement instead of #if may lead to
274 * "warning: null argument where non-null required": */
278 /* We can't (and don't really need to) bind the socket:
279 * we don't know from which local IP datagrams will be sent,
280 * but kernel will pick the same IP every time (unless routing
281 * table is changed), thus peer will see dgrams consistently
282 * coming from the same IP.
283 * We would like to connect the socket, but since peer's
284 * UDP code can be less perfect than ours, _peer's_ IP:port
285 * in replies may differ from IP:port we used to send
286 * our first packet. We can connect() only when we get
291 if (CMD_GET(option_mask32)) {
294 /* add filename and mode */
295 /* fill in packet if the filename fits into xbuf */
296 len = strlen(remote_file) + 1;
297 if (2 + len + sizeof("octet") >= io_bufsize) {
298 bb_error_msg("remote filename is too long");
301 strcpy(cp, remote_file);
303 /* add "mode" part of the package */
305 cp += sizeof("octet");
307 #if ENABLE_FEATURE_TFTP_BLOCKSIZE
308 if (blksize == TFTP_BLKSIZE_DEFAULT)
311 /* Non-standard blocksize: add option to pkt */
312 if ((&xbuf[io_bufsize - 1] - cp) < sizeof("blksize NNNNN")) {
313 bb_error_msg("remote filename is too long");
318 #endif /* ENABLE_TFTP */
320 #if ENABLE_FEATURE_TFTP_BLOCKSIZE
325 /* add "tsize", <nul>, size, <nul> */
327 cp += sizeof("tsize");
328 fstat(local_fd, &st);
329 cp += snprintf(cp, 10, "%u", (int) st.st_size) + 1;
332 if (blksize != TFTP_BLKSIZE_DEFAULT) {
333 /* add "blksize", <nul>, blksize, <nul> */
334 strcpy(cp, "blksize");
335 cp += sizeof("blksize");
336 cp += snprintf(cp, 6, "%d", blksize) + 1;
339 /* First packet is built, so skip packet generation */
343 /* Using mostly goto's - continue/break will be less clear
344 * in where we actually jump to */
346 /* Build ACK or DATA */
348 *((uint16_t*)cp) = htons(block_nr);
352 if (CMD_PUT(option_mask32)) {
354 len = full_read(local_fd, cp, blksize);
356 goto send_read_err_pkt;
358 if (len != blksize) {
365 *((uint16_t*)xbuf) = htons(opcode); /* fill in opcode part */
366 send_len = cp - xbuf;
367 /* NB: send_len value is preserved in code below
368 * for potential resend */
370 retries = TFTP_NUM_RETRIES; /* re-initialize */
371 waittime_ms = TFTP_TIMEOUT_MS;
374 #if ENABLE_DEBUG_TFTP
375 fprintf(stderr, "sending %u bytes\n", send_len);
376 for (cp = xbuf; cp < &xbuf[send_len]; cp++)
377 fprintf(stderr, "%02x ", (unsigned char) *cp);
378 fprintf(stderr, "\n");
380 xsendto(socket_fd, xbuf, send_len, &peer_lsa->u.sa, peer_lsa->len);
381 /* Was it final ACK? then exit */
382 if (finished && (opcode == TFTP_ACK))
387 /*pfd[0].fd = socket_fd;*/
388 pfd[0].events = POLLIN;
389 switch (safe_poll(pfd, 1, waittime_ms)) {
391 /*bb_perror_msg("poll"); - done in safe_poll */
396 bb_error_msg("timeout");
397 goto ret; /* no err packet sent */
400 /* exponential backoff with limit */
401 waittime_ms += waittime_ms/2;
402 if (waittime_ms > TFTP_MAXTIMEOUT_MS) {
403 waittime_ms = TFTP_MAXTIMEOUT_MS;
406 goto send_again; /* resend last sent pkt */
409 /* tftp (not tftpd!) receiving 1st packet */
410 our_lsa = ((void*)(ptrdiff_t)-1); /* not NULL */
411 len = recvfrom(socket_fd, rbuf, io_bufsize, 0,
412 &peer_lsa->u.sa, &peer_lsa->len);
413 /* Our first dgram went to port 69
414 * but reply may come from different one.
415 * Remember and use this new port (and IP) */
417 xconnect(socket_fd, &peer_lsa->u.sa, peer_lsa->len);
419 /* tftpd, or not the very first packet:
420 * socket is connect()ed, can just read from it. */
421 /* Don't full_read()!
422 * This is not TCP, one read == one pkt! */
423 len = safe_read(socket_fd, rbuf, io_bufsize);
426 goto send_read_err_pkt;
428 if (len < 4) { /* too small? */
433 /* Process recv'ed packet */
434 opcode = ntohs( ((uint16_t*)rbuf)[0] );
435 recv_blk = ntohs( ((uint16_t*)rbuf)[1] );
436 #if ENABLE_DEBUG_TFTP
437 fprintf(stderr, "received %d bytes: %04x %04x\n", len, opcode, recv_blk);
439 if (opcode == TFTP_ERROR) {
440 static const char errcode_str[] ALIGN1 =
446 "unknown transfer id\0"
447 "file already exists\0"
451 const char *msg = "";
453 if (len > 4 && rbuf[4] != '\0') {
455 rbuf[io_bufsize - 1] = '\0'; /* paranoia */
456 } else if (recv_blk <= 8) {
457 msg = nth_string(errcode_str, recv_blk);
459 bb_error_msg("server error: (%u) %s", recv_blk, msg);
463 #if ENABLE_FEATURE_TFTP_BLOCKSIZE
464 if (want_option_ack) {
466 if (opcode == TFTP_OACK) {
467 /* server seems to support options */
470 res = tftp_get_option("blksize", &rbuf[2], len - 2);
472 blksize = tftp_blksize_check(res, blksize);
474 error_pkt_reason = ERR_BAD_OPT;
477 io_bufsize = blksize + 4;
478 /* Send ACK for OACK ("block" no: 0) */
483 * "An option not acknowledged by the server
484 * must be ignored by the client and server
485 * as if it were never requested." */
487 bb_error_msg("server only supports blocksize of 512");
488 blksize = TFTP_BLKSIZE_DEFAULT;
489 io_bufsize = TFTP_BLKSIZE_DEFAULT + 4;
492 /* block_nr is already advanced to next block# we expect
493 * to get / block# we are about to send next time */
495 if (CMD_GET(option_mask32) && (opcode == TFTP_DATA)) {
496 if (recv_blk == block_nr) {
497 int sz = full_write(local_fd, &rbuf[4], len - 4);
499 strcpy((char*)error_pkt_str, bb_msg_write_error);
500 error_pkt_reason = ERR_WRITE;
506 continue; /* send ACK */
508 if (recv_blk == (block_nr - 1)) {
509 /* Server lost our TFTP_ACK. Resend it */
515 if (CMD_PUT(option_mask32) && (opcode == TFTP_ACK)) {
516 /* did peer ACK our last DATA pkt? */
517 if (recv_blk == (uint16_t) (block_nr - 1)) {
520 continue; /* send next block */
523 /* Awww... recv'd packet is not recognized! */
525 /* why recv_again? - rfc1123 says:
526 * "The sender (i.e., the side originating the DATA packets)
527 * must never resend the current DATA packet on receipt
528 * of a duplicate ACK".
529 * DATA pkts are resent ONLY on timeout.
530 * Thus "goto send_again" will ba a bad mistake above.
532 * http://en.wikipedia.org/wiki/Sorcerer's_Apprentice_Syndrome
534 } /* end of "while (1)" */
536 if (ENABLE_FEATURE_CLEAN_UP) {
542 return finished == 0; /* returns 1 on failure */
545 strcpy((char*)error_pkt_str, bb_msg_read_error);
547 if (error_pkt_str[0])
548 bb_error_msg((char*)error_pkt_str);
549 error_pkt[1] = TFTP_ERROR;
550 xsendto(socket_fd, error_pkt, 4 + 1 + strlen((char*)error_pkt_str),
551 &peer_lsa->u.sa, peer_lsa->len);
559 int tftp_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
560 int tftp_main(int argc ATTRIBUTE_UNUSED, char **argv)
562 len_and_sockaddr *peer_lsa;
563 const char *local_file = NULL;
564 const char *remote_file = NULL;
565 #if ENABLE_FEATURE_TFTP_BLOCKSIZE
566 const char *blksize_str = TFTP_BLKSIZE_DEFAULT_STR;
575 /* -p or -g is mandatory, and they are mutually exclusive */
576 opt_complementary = "" USE_FEATURE_TFTP_GET("g:") USE_FEATURE_TFTP_PUT("p:")
577 USE_GETPUT("g--p:p--g:");
579 USE_GETPUT(opt =) getopt32(argv,
580 USE_FEATURE_TFTP_GET("g") USE_FEATURE_TFTP_PUT("p")
581 "l:r:" USE_FEATURE_TFTP_BLOCKSIZE("b:"),
582 &local_file, &remote_file
583 USE_FEATURE_TFTP_BLOCKSIZE(, &blksize_str));
586 #if ENABLE_FEATURE_TFTP_BLOCKSIZE
587 /* Check if the blksize is valid:
588 * RFC2348 says between 8 and 65464 */
589 blksize = tftp_blksize_check(blksize_str, 65564);
591 //bb_error_msg("bad block size");
597 local_file = remote_file;
599 remote_file = local_file;
600 /* Error if filename or host is not known */
601 if (!remote_file || !argv[0])
604 port = bb_lookup_port(argv[1], "udp", 69);
605 peer_lsa = xhost2sockaddr(argv[0], port);
607 #if ENABLE_DEBUG_TFTP
608 fprintf(stderr, "using server '%s', remote_file '%s', local_file '%s'\n",
609 xmalloc_sockaddr2dotted(&peer_lsa->u.sa),
610 remote_file, local_file);
613 result = tftp_protocol(
614 NULL /*our_lsa*/, peer_lsa,
615 local_file, remote_file
616 USE_FEATURE_TFTP_BLOCKSIZE(USE_TFTPD(, NULL /*tsize*/))
617 USE_FEATURE_TFTP_BLOCKSIZE(, blksize)
620 if (result != EXIT_SUCCESS && NOT_LONE_DASH(local_file) && CMD_GET(opt)) {
626 #endif /* ENABLE_TFTP */
630 /* TODO: libbb candidate? */
631 static len_and_sockaddr *get_sock_lsa(int s)
633 len_and_sockaddr *lsa;
636 if (getsockname(s, NULL, &len) != 0)
638 lsa = xzalloc(LSA_LEN_SIZE + len);
640 getsockname(s, &lsa->u.sa, &lsa->len);
644 int tftpd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
645 int tftpd_main(int argc ATTRIBUTE_UNUSED, char **argv)
647 len_and_sockaddr *our_lsa;
648 len_and_sockaddr *peer_lsa;
649 char *local_file, *mode;
650 const char *error_msg;
651 int opt, result, opcode;
652 USE_FEATURE_TFTP_BLOCKSIZE(int blksize = TFTP_BLKSIZE_DEFAULT;)
653 USE_FEATURE_TFTP_BLOCKSIZE(char *tsize = NULL;)
657 our_lsa = get_sock_lsa(STDIN_FILENO);
659 bb_perror_msg_and_die("stdin is not a socket");
660 peer_lsa = xzalloc(LSA_LEN_SIZE + our_lsa->len);
661 peer_lsa->len = our_lsa->len;
663 /* Shifting to not collide with TFTP_OPTs */
664 opt = option_mask32 = TFTPD_OPT | (getopt32(argv, "rcu:", &user_opt) << 8);
669 result = recv_from_to(STDIN_FILENO, block_buf, sizeof(block_buf),
671 &peer_lsa->u.sa, &our_lsa->u.sa, our_lsa->len);
673 error_msg = "malformed packet";
674 opcode = ntohs(*(uint16_t*)block_buf);
675 if (result < 4 || result >= sizeof(block_buf)
676 || block_buf[result-1] != '\0'
677 || (USE_FEATURE_TFTP_PUT(opcode != TFTP_RRQ) /* not download */
679 USE_FEATURE_TFTP_GET(opcode != TFTP_WRQ) /* not upload */
684 local_file = block_buf + 2;
685 if (local_file[0] == '.' || strstr(local_file, "/.")) {
686 error_msg = "dot in file name";
689 mode = local_file + strlen(local_file) + 1;
690 if (mode >= block_buf + result || strcmp(mode, "octet") != 0) {
693 #if ENABLE_FEATURE_TFTP_BLOCKSIZE
696 char *opt_str = mode + sizeof("octet");
697 int opt_len = block_buf + result - opt_str;
699 res = tftp_get_option("blksize", opt_str, opt_len);
701 blksize = tftp_blksize_check(res, 65564);
703 error_pkt_reason = ERR_BAD_OPT;
704 /* will just send error pkt */
708 /* did client ask us about file size? */
709 tsize = tftp_get_option("tsize", opt_str, opt_len);
714 if (!ENABLE_FEATURE_TFTP_PUT || opcode == TFTP_WRQ) {
715 if (opt & TFTPD_OPT_r) {
716 /* This would mean "disk full" - not true */
717 /*error_pkt_reason = ERR_WRITE;*/
718 error_msg = bb_msg_write_error;
721 USE_GETPUT(option_mask32 |= TFTP_OPT_GET;) /* will receive file's data */
723 USE_GETPUT(option_mask32 |= TFTP_OPT_PUT;) /* will send file's data */
726 /* NB: if error_pkt_str or error_pkt_reason is set up,
727 * tftp_protocol() just sends one error pkt and returns */
730 close(STDIN_FILENO); /* close old, possibly wildcard socket */
731 /* tftp_protocol() will create new one, bound to particular local IP */
732 result = tftp_protocol(
734 local_file USE_TFTP(, NULL /*remote_file*/)
735 USE_FEATURE_TFTP_BLOCKSIZE(, tsize)
736 USE_FEATURE_TFTP_BLOCKSIZE(, blksize)
741 strcpy((char*)error_pkt_str, error_msg);
745 #endif /* ENABLE_TFTPD */
747 #endif /* ENABLE_FEATURE_TFTP_GET || ENABLE_FEATURE_TFTP_PUT */