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 )
95 #define INIT_G() do { } while (0)
97 #define error_pkt_reason (error_pkt[3])
98 #define error_pkt_str (error_pkt + 4)
101 #if ENABLE_FEATURE_TFTP_BLOCKSIZE
103 static int tftp_blksize_check(const char *blksize_str, int maxsize)
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);
111 || (blksize < 24) || (blksize > maxsize)
113 bb_error_msg("bad blocksize '%s'", blksize_str);
116 #if ENABLE_DEBUG_TFTP
117 bb_error_msg("using blksize %u", blksize);
122 static char *tftp_get_option(const char *option, char *buf, int len)
129 * "opt_name<NUL>opt_val<NUL>opt_name2<NUL>opt_val2<NUL>..." */
132 /* Make sure options are terminated correctly */
133 for (k = 0; k < len; k++) {
134 if (buf[k] == '\0') {
140 if (opt_val == 0) { /* it's "name" part */
141 if (strcasecmp(buf, option) == 0) {
144 } else if (opt_found) {
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))
168 #define remote_file NULL
170 #if !(ENABLE_FEATURE_TFTP_BLOCKSIZE && ENABLE_TFTPD)
173 #if !ENABLE_FEATURE_TFTP_BLOCKSIZE
174 enum { blksize = TFTP_BLKSIZE_DEFAULT };
177 struct pollfd pfd[1];
178 #define socket_fd (pfd[0].fd)
181 USE_FEATURE_TFTP_BLOCKSIZE(smallint want_option_ack = 0;)
182 smallint finished = 0;
186 int open_mode, local_fd;
187 int retries, waittime_ms;
188 int io_bufsize = blksize + 4;
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);
197 socket_fd = xsocket(peer_lsa->u.sa.sa_family, SOCK_DGRAM, 0);
198 setsockopt_reuseaddr(socket_fd);
203 if (!ENABLE_TFTP || our_lsa) {
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);
215 /* Is there an error already? Send pkt and bail out */
216 if (error_pkt_reason || error_pkt_str[0])
219 if (CMD_GET(option_mask32)) {
220 /* it's upload - we must ACK 1st packet (with filename)
221 * as if it's "block 0" */
226 struct passwd *pw = getpwnam(user_opt);
228 bb_error_msg_and_die("unknown user '%s'", user_opt);
229 change_identity(pw); /* initgroups, setgid, setuid */
233 /* Open local file (must be after changing user) */
234 if (CMD_PUT(option_mask32)) {
235 open_mode = O_RDONLY;
237 open_mode = O_WRONLY | O_TRUNC | O_CREAT;
239 if ((option_mask32 & (TFTPD_OPT+TFTPD_OPT_c)) == TFTPD_OPT) {
240 /* tftpd without -c */
241 open_mode = O_WRONLY | O_TRUNC;
245 if (!(option_mask32 & TFTPD_OPT)) {
246 local_fd = CMD_GET(option_mask32) ? STDOUT_FILENO : STDIN_FILENO;
247 if (NOT_LONE_DASH(local_file))
248 local_fd = xopen(local_file, open_mode);
250 local_fd = open(local_file, open_mode);
252 error_pkt_reason = ERR_NOFILE;
253 strcpy((char*)error_pkt_str, "can't open file");
258 if (!ENABLE_TFTP || our_lsa) {
259 /* gcc 4.3.1 would NOT optimize it out as it should! */
260 #if ENABLE_FEATURE_TFTP_BLOCKSIZE
261 if (blksize != TFTP_BLKSIZE_DEFAULT || tsize) {
262 /* Create and send OACK packet. */
263 /* For the download case, block_nr is still 1 -
264 * we expect 1st ACK from peer to be for (block_nr-1),
265 * that is, for "block 0" which is our OACK pkt */
267 goto add_blksize_opt;
271 /* Removing it, or using if() statement instead of #if may lead to
272 * "warning: null argument where non-null required": */
276 /* We can't (and don't really need to) bind the socket:
277 * we don't know from which local IP datagrams will be sent,
278 * but kernel will pick the same IP every time (unless routing
279 * table is changed), thus peer will see dgrams consistently
280 * coming from the same IP.
281 * We would like to connect the socket, but since peer's
282 * UDP code can be less perfect than ours, _peer's_ IP:port
283 * in replies may differ from IP:port we used to send
284 * our first packet. We can connect() only when we get
289 if (CMD_GET(option_mask32)) {
292 /* add filename and mode */
293 /* fill in packet if the filename fits into xbuf */
294 len = strlen(remote_file) + 1;
295 if (2 + len + sizeof("octet") >= io_bufsize) {
296 bb_error_msg("remote filename is too long");
299 strcpy(cp, remote_file);
301 /* add "mode" part of the package */
303 cp += sizeof("octet");
305 #if ENABLE_FEATURE_TFTP_BLOCKSIZE
306 if (blksize == TFTP_BLKSIZE_DEFAULT)
309 /* Non-standard blocksize: add option to pkt */
310 if ((&xbuf[io_bufsize - 1] - cp) < sizeof("blksize NNNNN")) {
311 bb_error_msg("remote filename is too long");
316 #endif /* ENABLE_TFTP */
318 #if ENABLE_FEATURE_TFTP_BLOCKSIZE
323 /* add "tsize", <nul>, size, <nul> */
325 cp += sizeof("tsize");
326 fstat(local_fd, &st);
327 cp += snprintf(cp, 10, "%u", (int) st.st_size) + 1;
330 if (blksize != TFTP_BLKSIZE_DEFAULT) {
331 /* add "blksize", <nul>, blksize, <nul> */
332 strcpy(cp, "blksize");
333 cp += sizeof("blksize");
334 cp += snprintf(cp, 6, "%d", blksize) + 1;
337 /* First packet is built, so skip packet generation */
341 /* Using mostly goto's - continue/break will be less clear
342 * in where we actually jump to */
344 /* Build ACK or DATA */
346 *((uint16_t*)cp) = htons(block_nr);
350 if (CMD_PUT(option_mask32)) {
352 len = full_read(local_fd, cp, blksize);
354 goto send_read_err_pkt;
356 if (len != blksize) {
363 *((uint16_t*)xbuf) = htons(opcode); /* fill in opcode part */
364 send_len = cp - xbuf;
365 /* NB: send_len value is preserved in code below
366 * for potential resend */
368 retries = TFTP_NUM_RETRIES; /* re-initialize */
369 waittime_ms = TFTP_TIMEOUT_MS;
372 #if ENABLE_DEBUG_TFTP
373 fprintf(stderr, "sending %u bytes\n", send_len);
374 for (cp = xbuf; cp < &xbuf[send_len]; cp++)
375 fprintf(stderr, "%02x ", (unsigned char) *cp);
376 fprintf(stderr, "\n");
378 xsendto(socket_fd, xbuf, send_len, &peer_lsa->u.sa, peer_lsa->len);
379 /* Was it final ACK? then exit */
380 if (finished && (opcode == TFTP_ACK))
385 /*pfd[0].fd = socket_fd;*/
386 pfd[0].events = POLLIN;
387 switch (safe_poll(pfd, 1, waittime_ms)) {
389 /*bb_perror_msg("poll"); - done in safe_poll */
394 bb_error_msg("timeout");
395 goto ret; /* no err packet sent */
398 /* exponential backoff with limit */
399 waittime_ms += waittime_ms/2;
400 if (waittime_ms > TFTP_MAXTIMEOUT_MS) {
401 waittime_ms = TFTP_MAXTIMEOUT_MS;
404 goto send_again; /* resend last sent pkt */
407 /* tftp (not tftpd!) receiving 1st packet */
408 our_lsa = ((void*)(ptrdiff_t)-1); /* not NULL */
409 len = recvfrom(socket_fd, rbuf, io_bufsize, 0,
410 &peer_lsa->u.sa, &peer_lsa->len);
411 /* Our first dgram went to port 69
412 * but reply may come from different one.
413 * Remember and use this new port (and IP) */
415 xconnect(socket_fd, &peer_lsa->u.sa, peer_lsa->len);
417 /* tftpd, or not the very first packet:
418 * socket is connect()ed, can just read from it. */
419 /* Don't full_read()!
420 * This is not TCP, one read == one pkt! */
421 len = safe_read(socket_fd, rbuf, io_bufsize);
424 goto send_read_err_pkt;
426 if (len < 4) { /* too small? */
431 /* Process recv'ed packet */
432 opcode = ntohs( ((uint16_t*)rbuf)[0] );
433 recv_blk = ntohs( ((uint16_t*)rbuf)[1] );
434 #if ENABLE_DEBUG_TFTP
435 fprintf(stderr, "received %d bytes: %04x %04x\n", len, opcode, recv_blk);
437 if (opcode == TFTP_ERROR) {
438 static const char errcode_str[] ALIGN1 =
444 "unknown transfer id\0"
445 "file already exists\0"
449 const char *msg = "";
451 if (len > 4 && rbuf[4] != '\0') {
453 rbuf[io_bufsize - 1] = '\0'; /* paranoia */
454 } else if (recv_blk <= 8) {
455 msg = nth_string(errcode_str, recv_blk);
457 bb_error_msg("server error: (%u) %s", recv_blk, msg);
461 #if ENABLE_FEATURE_TFTP_BLOCKSIZE
462 if (want_option_ack) {
464 if (opcode == TFTP_OACK) {
465 /* server seems to support options */
468 res = tftp_get_option("blksize", &rbuf[2], len - 2);
470 blksize = tftp_blksize_check(res, blksize);
472 error_pkt_reason = ERR_BAD_OPT;
475 io_bufsize = blksize + 4;
476 /* Send ACK for OACK ("block" no: 0) */
481 * "An option not acknowledged by the server
482 * must be ignored by the client and server
483 * as if it were never requested." */
485 bb_error_msg("server only supports blocksize of 512");
486 blksize = TFTP_BLKSIZE_DEFAULT;
487 io_bufsize = TFTP_BLKSIZE_DEFAULT + 4;
490 /* block_nr is already advanced to next block# we expect
491 * to get / block# we are about to send next time */
493 if (CMD_GET(option_mask32) && (opcode == TFTP_DATA)) {
494 if (recv_blk == block_nr) {
495 int sz = full_write(local_fd, &rbuf[4], len - 4);
497 strcpy((char*)error_pkt_str, bb_msg_write_error);
498 error_pkt_reason = ERR_WRITE;
504 continue; /* send ACK */
506 if (recv_blk == (block_nr - 1)) {
507 /* Server lost our TFTP_ACK. Resend it */
513 if (CMD_PUT(option_mask32) && (opcode == TFTP_ACK)) {
514 /* did peer ACK our last DATA pkt? */
515 if (recv_blk == (uint16_t) (block_nr - 1)) {
518 continue; /* send next block */
521 /* Awww... recv'd packet is not recognized! */
523 /* why recv_again? - rfc1123 says:
524 * "The sender (i.e., the side originating the DATA packets)
525 * must never resend the current DATA packet on receipt
526 * of a duplicate ACK".
527 * DATA pkts are resent ONLY on timeout.
528 * Thus "goto send_again" will ba a bad mistake above.
530 * http://en.wikipedia.org/wiki/Sorcerer's_Apprentice_Syndrome
532 } /* end of "while (1)" */
534 if (ENABLE_FEATURE_CLEAN_UP) {
540 return finished == 0; /* returns 1 on failure */
543 strcpy((char*)error_pkt_str, bb_msg_read_error);
545 if (error_pkt_str[0])
546 bb_error_msg((char*)error_pkt_str);
547 error_pkt[1] = TFTP_ERROR;
548 xsendto(socket_fd, error_pkt, 4 + 1 + strlen((char*)error_pkt_str),
549 &peer_lsa->u.sa, peer_lsa->len);
557 int tftp_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
558 int tftp_main(int argc ATTRIBUTE_UNUSED, char **argv)
560 len_and_sockaddr *peer_lsa;
561 const char *local_file = NULL;
562 const char *remote_file = NULL;
563 #if ENABLE_FEATURE_TFTP_BLOCKSIZE
564 const char *blksize_str = TFTP_BLKSIZE_DEFAULT_STR;
573 /* -p or -g is mandatory, and they are mutually exclusive */
574 opt_complementary = "" USE_FEATURE_TFTP_GET("g:") USE_FEATURE_TFTP_PUT("p:")
575 USE_GETPUT("g--p:p--g:");
577 USE_GETPUT(opt =) getopt32(argv,
578 USE_FEATURE_TFTP_GET("g") USE_FEATURE_TFTP_PUT("p")
579 "l:r:" USE_FEATURE_TFTP_BLOCKSIZE("b:"),
580 &local_file, &remote_file
581 USE_FEATURE_TFTP_BLOCKSIZE(, &blksize_str));
584 #if ENABLE_FEATURE_TFTP_BLOCKSIZE
585 /* Check if the blksize is valid:
586 * RFC2348 says between 8 and 65464 */
587 blksize = tftp_blksize_check(blksize_str, 65564);
589 //bb_error_msg("bad block size");
595 local_file = remote_file;
597 remote_file = local_file;
598 /* Error if filename or host is not known */
599 if (!remote_file || !argv[0])
602 port = bb_lookup_port(argv[1], "udp", 69);
603 peer_lsa = xhost2sockaddr(argv[0], port);
605 #if ENABLE_DEBUG_TFTP
606 fprintf(stderr, "using server '%s', remote_file '%s', local_file '%s'\n",
607 xmalloc_sockaddr2dotted(&peer_lsa->u.sa),
608 remote_file, local_file);
611 result = tftp_protocol(
612 NULL /*our_lsa*/, peer_lsa,
613 local_file, remote_file
614 USE_FEATURE_TFTP_BLOCKSIZE(USE_TFTPD(, NULL /*tsize*/))
615 USE_FEATURE_TFTP_BLOCKSIZE(, blksize)
618 if (result != EXIT_SUCCESS && NOT_LONE_DASH(local_file) && CMD_GET(opt)) {
624 #endif /* ENABLE_TFTP */
628 /* TODO: libbb candidate? */
629 static len_and_sockaddr *get_sock_lsa(int s)
631 len_and_sockaddr *lsa;
634 if (getsockname(s, NULL, &len) != 0)
636 lsa = xzalloc(LSA_LEN_SIZE + len);
638 getsockname(s, &lsa->u.sa, &lsa->len);
642 int tftpd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
643 int tftpd_main(int argc ATTRIBUTE_UNUSED, char **argv)
645 len_and_sockaddr *our_lsa;
646 len_and_sockaddr *peer_lsa;
647 char *local_file, *mode;
648 const char *error_msg;
649 int opt, result, opcode;
650 USE_FEATURE_TFTP_BLOCKSIZE(int blksize = TFTP_BLKSIZE_DEFAULT;)
651 USE_FEATURE_TFTP_BLOCKSIZE(char *tsize = NULL;)
655 our_lsa = get_sock_lsa(STDIN_FILENO);
657 bb_perror_msg_and_die("stdin is not a socket");
658 peer_lsa = xzalloc(LSA_LEN_SIZE + our_lsa->len);
659 peer_lsa->len = our_lsa->len;
661 /* Shifting to not collide with TFTP_OPTs */
662 opt = option_mask32 = TFTPD_OPT | (getopt32(argv, "rcu:", &user_opt) << 8);
667 result = recv_from_to(STDIN_FILENO, block_buf, sizeof(block_buf),
669 &peer_lsa->u.sa, &our_lsa->u.sa, our_lsa->len);
671 error_msg = "malformed packet";
672 opcode = ntohs(*(uint16_t*)block_buf);
673 if (result < 4 || result >= sizeof(block_buf)
674 || block_buf[result-1] != '\0'
675 || (USE_FEATURE_TFTP_PUT(opcode != TFTP_RRQ) /* not download */
677 USE_FEATURE_TFTP_GET(opcode != TFTP_WRQ) /* not upload */
682 local_file = block_buf + 2;
683 if (local_file[0] == '.' || strstr(local_file, "/.")) {
684 error_msg = "dot in file name";
687 mode = local_file + strlen(local_file) + 1;
688 if (mode >= block_buf + result || strcmp(mode, "octet") != 0) {
691 #if ENABLE_FEATURE_TFTP_BLOCKSIZE
694 char *opt_str = mode + sizeof("octet");
695 int opt_len = block_buf + result - opt_str;
697 res = tftp_get_option("blksize", opt_str, opt_len);
699 blksize = tftp_blksize_check(res, 65564);
701 error_pkt_reason = ERR_BAD_OPT;
702 /* will just send error pkt */
706 /* did client ask us about file size? */
707 tsize = tftp_get_option("tsize", opt_str, opt_len);
712 if (!ENABLE_FEATURE_TFTP_PUT || opcode == TFTP_WRQ) {
713 if (opt & TFTPD_OPT_r) {
714 /* This would mean "disk full" - not true */
715 /*error_pkt_reason = ERR_WRITE;*/
716 error_msg = bb_msg_write_error;
719 USE_GETPUT(option_mask32 |= TFTP_OPT_GET;) /* will receive file's data */
721 USE_GETPUT(option_mask32 |= TFTP_OPT_PUT;) /* will send file's data */
724 /* NB: if error_pkt_str or error_pkt_reason is set up,
725 * tftp_protocol() just sends one error pkt and returns */
728 close(STDIN_FILENO); /* close old, possibly wildcard socket */
729 /* tftp_protocol() will create new one, bound to particular local IP */
730 result = tftp_protocol(
732 local_file USE_TFTP(, NULL /*remote_file*/)
733 USE_FEATURE_TFTP_BLOCKSIZE(, tsize)
734 USE_FEATURE_TFTP_BLOCKSIZE(, blksize)
739 strcpy((char*)error_pkt_str, error_msg);
743 #endif /* ENABLE_TFTPD */
745 #endif /* ENABLE_FEATURE_TFTP_GET || ENABLE_FEATURE_TFTP_PUT */