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 IF_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 IF_GETPUT(...)
72 #define CMD_GET(cmd) 0
73 #define CMD_PUT(cmd) 1
75 #define IF_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_TFTP_DEBUG
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 IF_TFTP(, const char *remote_file)
164 IF_FEATURE_TFTP_BLOCKSIZE(IF_TFTPD(, void *tsize))
165 IF_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 IF_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 = xgetpwnam(user_opt);
227 change_identity(pw); /* initgroups, setgid, setuid */
231 /* Open local file (must be after changing user) */
232 if (CMD_PUT(option_mask32)) {
233 open_mode = O_RDONLY;
235 open_mode = O_WRONLY | O_TRUNC | O_CREAT;
237 if ((option_mask32 & (TFTPD_OPT+TFTPD_OPT_c)) == TFTPD_OPT) {
238 /* tftpd without -c */
239 open_mode = O_WRONLY | O_TRUNC;
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);
248 local_fd = open(local_file, open_mode);
250 error_pkt_reason = ERR_NOFILE;
251 strcpy((char*)error_pkt_str, "can't open file");
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 */
265 goto add_blksize_opt;
269 /* Removing it, or using if() statement instead of #if may lead to
270 * "warning: null argument where non-null required": */
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
287 if (CMD_GET(option_mask32)) {
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");
297 strcpy(cp, remote_file);
299 /* add "mode" part of the package */
301 cp += sizeof("octet");
303 #if ENABLE_FEATURE_TFTP_BLOCKSIZE
304 if (blksize == TFTP_BLKSIZE_DEFAULT)
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");
314 #endif /* ENABLE_TFTP */
316 #if ENABLE_FEATURE_TFTP_BLOCKSIZE
321 /* add "tsize", <nul>, size, <nul> */
323 cp += sizeof("tsize");
324 fstat(local_fd, &st);
325 cp += snprintf(cp, 10, "%u", (int) st.st_size) + 1;
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;
335 /* First packet is built, so skip packet generation */
339 /* Using mostly goto's - continue/break will be less clear
340 * in where we actually jump to */
342 /* Build ACK or DATA */
344 *((uint16_t*)cp) = htons(block_nr);
348 if (CMD_PUT(option_mask32)) {
350 len = full_read(local_fd, cp, blksize);
352 goto send_read_err_pkt;
354 if (len != blksize) {
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 */
366 retries = TFTP_NUM_RETRIES; /* re-initialize */
367 waittime_ms = TFTP_TIMEOUT_MS;
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");
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))
383 /*pfd[0].fd = socket_fd;*/
384 pfd[0].events = POLLIN;
385 switch (safe_poll(pfd, 1, waittime_ms)) {
387 /*bb_perror_msg("poll"); - done in safe_poll */
392 bb_error_msg("timeout");
393 goto ret; /* no err packet sent */
396 /* exponential backoff with limit */
397 waittime_ms += waittime_ms/2;
398 if (waittime_ms > TFTP_MAXTIMEOUT_MS) {
399 waittime_ms = TFTP_MAXTIMEOUT_MS;
402 goto send_again; /* resend last sent pkt */
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) */
413 xconnect(socket_fd, &peer_lsa->u.sa, peer_lsa->len);
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);
422 goto send_read_err_pkt;
424 if (len < 4) { /* too small? */
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);
435 if (opcode == TFTP_ERROR) {
436 static const char errcode_str[] ALIGN1 =
442 "unknown transfer id\0"
443 "file already exists\0"
447 const char *msg = "";
449 if (len > 4 && rbuf[4] != '\0') {
451 rbuf[io_bufsize - 1] = '\0'; /* paranoia */
452 } else if (recv_blk <= 8) {
453 msg = nth_string(errcode_str, recv_blk);
455 bb_error_msg("server error: (%u) %s", recv_blk, msg);
459 #if ENABLE_FEATURE_TFTP_BLOCKSIZE
460 if (want_option_ack) {
462 if (opcode == TFTP_OACK) {
463 /* server seems to support options */
466 res = tftp_get_option("blksize", &rbuf[2], len - 2);
468 blksize = tftp_blksize_check(res, blksize);
470 error_pkt_reason = ERR_BAD_OPT;
473 io_bufsize = blksize + 4;
474 /* Send ACK for OACK ("block" no: 0) */
479 * "An option not acknowledged by the server
480 * must be ignored by the client and server
481 * as if it were never requested." */
483 bb_error_msg("server only supports blocksize of 512");
484 blksize = TFTP_BLKSIZE_DEFAULT;
485 io_bufsize = TFTP_BLKSIZE_DEFAULT + 4;
488 /* block_nr is already advanced to next block# we expect
489 * to get / block# we are about to send next time */
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);
495 strcpy((char*)error_pkt_str, bb_msg_write_error);
496 error_pkt_reason = ERR_WRITE;
502 continue; /* send ACK */
504 if (recv_blk == (block_nr - 1)) {
505 /* Server lost our TFTP_ACK. Resend it */
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)) {
516 continue; /* send next block */
519 /* Awww... recv'd packet is not recognized! */
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.
528 * http://en.wikipedia.org/wiki/Sorcerer's_Apprentice_Syndrome
530 } /* end of "while (1)" */
532 if (ENABLE_FEATURE_CLEAN_UP) {
538 return finished == 0; /* returns 1 on failure */
541 strcpy((char*)error_pkt_str, bb_msg_read_error);
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);
555 int tftp_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
556 int tftp_main(int argc UNUSED_PARAM, char **argv)
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;
571 /* -p or -g is mandatory, and they are mutually exclusive */
572 opt_complementary = "" IF_FEATURE_TFTP_GET("g:") IF_FEATURE_TFTP_PUT("p:")
573 IF_GETPUT("g--p:p--g:");
575 IF_GETPUT(opt =) getopt32(argv,
576 IF_FEATURE_TFTP_GET("g") IF_FEATURE_TFTP_PUT("p")
577 "l:r:" IF_FEATURE_TFTP_BLOCKSIZE("b:"),
578 &local_file, &remote_file
579 IF_FEATURE_TFTP_BLOCKSIZE(, &blksize_str));
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);
587 //bb_error_msg("bad block size");
594 const char *slash = strrchr(remote_file, '/');
595 local_file = slash ? slash + 1 : remote_file;
598 remote_file = local_file;
601 /* Error if filename or host is not known */
602 if (!remote_file || !argv[0])
605 port = bb_lookup_port(argv[1], "udp", 69);
606 peer_lsa = xhost2sockaddr(argv[0], port);
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);
614 result = tftp_protocol(
615 NULL /*our_lsa*/, peer_lsa,
616 local_file, remote_file
617 IF_FEATURE_TFTP_BLOCKSIZE(IF_TFTPD(, NULL /*tsize*/))
618 IF_FEATURE_TFTP_BLOCKSIZE(, blksize)
621 if (result != EXIT_SUCCESS && NOT_LONE_DASH(local_file) && CMD_GET(opt)) {
627 #endif /* ENABLE_TFTP */
630 int tftpd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
631 int tftpd_main(int argc UNUSED_PARAM, char **argv)
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 IF_FEATURE_TFTP_BLOCKSIZE(int blksize = TFTP_BLKSIZE_DEFAULT;)
639 IF_FEATURE_TFTP_BLOCKSIZE(char *tsize = NULL;)
643 our_lsa = get_sock_lsa(STDIN_FILENO);
645 /* This is confusing:
646 *bb_error_msg_and_die("stdin is not a socket");
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
653 peer_lsa = xzalloc(LSA_LEN_SIZE + our_lsa->len);
654 peer_lsa->len = our_lsa->len;
656 /* Shifting to not collide with TFTP_OPTs */
657 opt = option_mask32 = TFTPD_OPT | (getopt32(argv, "rcu:", &user_opt) << 8);
662 result = recv_from_to(STDIN_FILENO, block_buf, sizeof(block_buf),
664 &peer_lsa->u.sa, &our_lsa->u.sa, our_lsa->len);
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 || (IF_FEATURE_TFTP_PUT(opcode != TFTP_RRQ) /* not download */
672 IF_FEATURE_TFTP_GET(opcode != TFTP_WRQ) /* not upload */
677 local_file = block_buf + 2;
678 if (local_file[0] == '.' || strstr(local_file, "/.")) {
679 error_msg = "dot in file name";
682 mode = local_file + strlen(local_file) + 1;
683 if (mode >= block_buf + result || strcmp(mode, "octet") != 0) {
686 #if ENABLE_FEATURE_TFTP_BLOCKSIZE
689 char *opt_str = mode + sizeof("octet");
690 int opt_len = block_buf + result - opt_str;
692 res = tftp_get_option("blksize", opt_str, opt_len);
694 blksize = tftp_blksize_check(res, 65564);
696 error_pkt_reason = ERR_BAD_OPT;
697 /* will just send error pkt */
701 /* did client ask us about file size? */
702 tsize = tftp_get_option("tsize", opt_str, opt_len);
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;
714 IF_GETPUT(option_mask32 |= TFTP_OPT_GET;) /* will receive file's data */
716 IF_GETPUT(option_mask32 |= TFTP_OPT_PUT;) /* will send file's data */
719 /* NB: if error_pkt_str or error_pkt_reason is set up,
720 * tftp_protocol() just sends one error pkt and returns */
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(
727 local_file IF_TFTP(, NULL /*remote_file*/)
728 IF_FEATURE_TFTP_BLOCKSIZE(, tsize)
729 IF_FEATURE_TFTP_BLOCKSIZE(, blksize)
734 strcpy((char*)error_pkt_str, error_msg);
738 #endif /* ENABLE_TFTPD */
740 #endif /* ENABLE_FEATURE_TFTP_GET || ENABLE_FEATURE_TFTP_PUT */