source: branches/3.2/mindi-busybox/networking/tftp.c @ 3232

Last change on this file since 3232 was 3232, checked in by bruno, 6 years ago
  • Update mindi-busybox to 1.21.1
File size: 24.2 KB
Line 
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 <syslog.h>
55
56#if ENABLE_FEATURE_TFTP_GET || ENABLE_FEATURE_TFTP_PUT
57
58#define TFTP_BLKSIZE_DEFAULT       512  /* according to RFC 1350, don't change */
59#define TFTP_BLKSIZE_DEFAULT_STR "512"
60/* Was 50 ms but users asked to bump it up a bit */
61#define TFTP_TIMEOUT_MS            100
62#define TFTP_MAXTIMEOUT_MS        2000
63#define TFTP_NUM_RETRIES            12  /* number of backed-off retries */
64
65/* opcodes we support */
66#define TFTP_RRQ   1
67#define TFTP_WRQ   2
68#define TFTP_DATA  3
69#define TFTP_ACK   4
70#define TFTP_ERROR 5
71#define TFTP_OACK  6
72
73/* error codes sent over network (we use only 0, 1, 3 and 8) */
74/* generic (error message is included in the packet) */
75#define ERR_UNSPEC   0
76#define ERR_NOFILE   1
77#define ERR_ACCESS   2
78/* disk full or allocation exceeded */
79#define ERR_WRITE    3
80#define ERR_OP       4
81#define ERR_BAD_ID   5
82#define ERR_EXIST    6
83#define ERR_BAD_USER 7
84#define ERR_BAD_OPT  8
85
86/* masks coming from getopt32 */
87enum {
88    TFTP_OPT_GET = (1 << 0),
89    TFTP_OPT_PUT = (1 << 1),
90    /* pseudo option: if set, it's tftpd */
91    TFTPD_OPT = (1 << 7) * ENABLE_TFTPD,
92    TFTPD_OPT_r = (1 << 8) * ENABLE_TFTPD,
93    TFTPD_OPT_c = (1 << 9) * ENABLE_TFTPD,
94    TFTPD_OPT_u = (1 << 10) * ENABLE_TFTPD,
95    TFTPD_OPT_l = (1 << 11) * ENABLE_TFTPD,
96};
97
98#if ENABLE_FEATURE_TFTP_GET && !ENABLE_FEATURE_TFTP_PUT
99#define IF_GETPUT(...)
100#define CMD_GET(cmd) 1
101#define CMD_PUT(cmd) 0
102#elif !ENABLE_FEATURE_TFTP_GET && ENABLE_FEATURE_TFTP_PUT
103#define IF_GETPUT(...)
104#define CMD_GET(cmd) 0
105#define CMD_PUT(cmd) 1
106#else
107#define IF_GETPUT(...) __VA_ARGS__
108#define CMD_GET(cmd) ((cmd) & TFTP_OPT_GET)
109#define CMD_PUT(cmd) ((cmd) & TFTP_OPT_PUT)
110#endif
111/* NB: in the code below
112 * CMD_GET(cmd) and CMD_PUT(cmd) are mutually exclusive
113 */
114
115
116struct globals {
117    /* u16 TFTP_ERROR; u16 reason; both network-endian, then error text: */
118    uint8_t error_pkt[4 + 32];
119    struct passwd *pw;
120    /* used in tftpd_main(), a bit big for stack: */
121    char block_buf[TFTP_BLKSIZE_DEFAULT];
122#if ENABLE_FEATURE_TFTP_PROGRESS_BAR
123    off_t pos;
124    off_t size;
125    const char *file;
126    bb_progress_t pmt;
127#endif
128} FIX_ALIASING;
129#define G (*(struct globals*)&bb_common_bufsiz1)
130struct BUG_G_too_big {
131    char BUG_G_too_big[sizeof(G) <= COMMON_BUFSIZE ? 1 : -1];
132};
133#define INIT_G() do { } while (0)
134
135#define G_error_pkt_reason (G.error_pkt[3])
136#define G_error_pkt_str    ((char*)(G.error_pkt + 4))
137
138#if ENABLE_FEATURE_TFTP_PROGRESS_BAR
139static void tftp_progress_update(void)
140{
141    bb_progress_update(&G.pmt, 0, G.pos, G.size);
142}
143static void tftp_progress_init(void)
144{
145    bb_progress_init(&G.pmt, G.file);
146    tftp_progress_update();
147}
148static void tftp_progress_done(void)
149{
150    if (is_bb_progress_inited(&G.pmt)) {
151        tftp_progress_update();
152        bb_putchar_stderr('\n');
153        bb_progress_free(&G.pmt);
154    }
155}
156#else
157# define tftp_progress_init() ((void)0)
158# define tftp_progress_done() ((void)0)
159#endif
160
161#if ENABLE_FEATURE_TFTP_BLOCKSIZE
162
163static int tftp_blksize_check(const char *blksize_str, int maxsize)
164{
165    /* Check if the blksize is valid:
166     * RFC2348 says between 8 and 65464,
167     * but our implementation makes it impossible
168     * to use blksizes smaller than 22 octets. */
169    unsigned blksize = bb_strtou(blksize_str, NULL, 10);
170    if (errno
171     || (blksize < 24) || (blksize > maxsize)
172    ) {
173        bb_error_msg("bad blocksize '%s'", blksize_str);
174        return -1;
175    }
176# if ENABLE_TFTP_DEBUG
177    bb_error_msg("using blksize %u", blksize);
178# endif
179    return blksize;
180}
181
182static char *tftp_get_option(const char *option, char *buf, int len)
183{
184    int opt_val = 0;
185    int opt_found = 0;
186    int k;
187
188    /* buf points to:
189     * "opt_name<NUL>opt_val<NUL>opt_name2<NUL>opt_val2<NUL>..." */
190
191    while (len > 0) {
192        /* Make sure options are terminated correctly */
193        for (k = 0; k < len; k++) {
194            if (buf[k] == '\0') {
195                goto nul_found;
196            }
197        }
198        return NULL;
199 nul_found:
200        if (opt_val == 0) { /* it's "name" part */
201            if (strcasecmp(buf, option) == 0) {
202                opt_found = 1;
203            }
204        } else if (opt_found) {
205            return buf;
206        }
207
208        k++;
209        buf += k;
210        len -= k;
211        opt_val ^= 1;
212    }
213
214    return NULL;
215}
216
217#endif
218
219static int tftp_protocol(
220        /* NULL if tftp, !NULL if tftpd: */
221        len_and_sockaddr *our_lsa,
222        len_and_sockaddr *peer_lsa,
223        const char *local_file
224        IF_TFTP(, const char *remote_file)
225#if !ENABLE_TFTP
226# define remote_file NULL
227#endif
228        /* 1 for tftp; 1/0 for tftpd depending whether client asked about it: */
229        IF_FEATURE_TFTP_BLOCKSIZE(, int want_transfer_size)
230        IF_FEATURE_TFTP_BLOCKSIZE(, int blksize))
231{
232#if !ENABLE_FEATURE_TFTP_BLOCKSIZE
233    enum { blksize = TFTP_BLKSIZE_DEFAULT };
234#endif
235
236    struct pollfd pfd[1];
237#define socket_fd (pfd[0].fd)
238    int len;
239    int send_len;
240    IF_FEATURE_TFTP_BLOCKSIZE(smallint expect_OACK = 0;)
241    smallint finished = 0;
242    uint16_t opcode;
243    uint16_t block_nr;
244    uint16_t recv_blk;
245    int open_mode, local_fd;
246    int retries, waittime_ms;
247    int io_bufsize = blksize + 4;
248    char *cp;
249    /* Can't use RESERVE_CONFIG_BUFFER here since the allocation
250     * size varies meaning BUFFERS_GO_ON_STACK would fail.
251     *
252     * We must keep the transmit and receive buffers separate
253     * in case we rcv a garbage pkt - we need to rexmit the last pkt.
254     */
255    char *xbuf = xmalloc(io_bufsize);
256    char *rbuf = xmalloc(io_bufsize);
257
258    socket_fd = xsocket(peer_lsa->u.sa.sa_family, SOCK_DGRAM, 0);
259    setsockopt_reuseaddr(socket_fd);
260
261    if (!ENABLE_TFTP || our_lsa) { /* tftpd */
262        /* Create a socket which is:
263         * 1. bound to IP:port peer sent 1st datagram to,
264         * 2. connected to peer's IP:port
265         * This way we will answer from the IP:port peer
266         * expects, will not get any other packets on
267         * the socket, and also plain read/write will work. */
268        xbind(socket_fd, &our_lsa->u.sa, our_lsa->len);
269        xconnect(socket_fd, &peer_lsa->u.sa, peer_lsa->len);
270
271        /* Is there an error already? Send pkt and bail out */
272        if (G_error_pkt_reason || G_error_pkt_str[0])
273            goto send_err_pkt;
274
275        if (G.pw) {
276            change_identity(G.pw); /* initgroups, setgid, setuid */
277        }
278    }
279
280    /* Prepare open mode */
281    if (CMD_PUT(option_mask32)) {
282        open_mode = O_RDONLY;
283    } else {
284        open_mode = O_WRONLY | O_TRUNC | O_CREAT;
285#if ENABLE_TFTPD
286        if ((option_mask32 & (TFTPD_OPT+TFTPD_OPT_c)) == TFTPD_OPT) {
287            /* tftpd without -c */
288            open_mode = O_WRONLY | O_TRUNC;
289        }
290#endif
291    }
292
293    /* Examples of network traffic.
294     * Note two cases when ACKs with block# of 0 are sent.
295     *
296     * Download without options:
297     * tftp -> "\0\1FILENAME\0octet\0"
298     *         "\0\3\0\1FILEDATA..." <- tftpd
299     * tftp -> "\0\4\0\1"
300     * ...
301     * Download with option of blksize 16384:
302     * tftp -> "\0\1FILENAME\0octet\0blksize\00016384\0"
303     *         "\0\6blksize\00016384\0" <- tftpd
304     * tftp -> "\0\4\0\0"
305     *         "\0\3\0\1FILEDATA..." <- tftpd
306     * tftp -> "\0\4\0\1"
307     * ...
308     * Upload without options:
309     * tftp -> "\0\2FILENAME\0octet\0"
310     *         "\0\4\0\0" <- tftpd
311     * tftp -> "\0\3\0\1FILEDATA..."
312     *         "\0\4\0\1" <- tftpd
313     * ...
314     * Upload with option of blksize 16384:
315     * tftp -> "\0\2FILENAME\0octet\0blksize\00016384\0"
316     *         "\0\6blksize\00016384\0" <- tftpd
317     * tftp -> "\0\3\0\1FILEDATA..."
318     *         "\0\4\0\1" <- tftpd
319     * ...
320     */
321    block_nr = 1;
322    cp = xbuf + 2;
323
324    if (!ENABLE_TFTP || our_lsa) { /* tftpd */
325        /* Open file (must be after changing user) */
326        local_fd = open(local_file, open_mode, 0666);
327        if (local_fd < 0) {
328            G_error_pkt_reason = ERR_NOFILE;
329            strcpy(G_error_pkt_str, "can't open file");
330            goto send_err_pkt;
331        }
332/* gcc 4.3.1 would NOT optimize it out as it should! */
333#if ENABLE_FEATURE_TFTP_BLOCKSIZE
334        if (blksize != TFTP_BLKSIZE_DEFAULT || want_transfer_size) {
335            /* Create and send OACK packet. */
336            /* For the download case, block_nr is still 1 -
337             * we expect 1st ACK from peer to be for (block_nr-1),
338             * that is, for "block 0" which is our OACK pkt */
339            opcode = TFTP_OACK;
340            goto add_blksize_opt;
341        }
342#endif
343        if (CMD_GET(option_mask32)) {
344            /* It's upload and we don't send OACK.
345             * We must ACK 1st packet (with filename)
346             * as if it is "block 0" */
347            block_nr = 0;
348        }
349
350    } else { /* tftp */
351        /* Open file (must be after changing user) */
352        local_fd = CMD_GET(option_mask32) ? STDOUT_FILENO : STDIN_FILENO;
353        if (NOT_LONE_DASH(local_file))
354            local_fd = xopen(local_file, open_mode);
355/* Removing #if, or using if() statement instead of #if may lead to
356 * "warning: null argument where non-null required": */
357#if ENABLE_TFTP
358        /* tftp */
359
360        /* We can't (and don't really need to) bind the socket:
361         * we don't know from which local IP datagrams will be sent,
362         * but kernel will pick the same IP every time (unless routing
363         * table is changed), thus peer will see dgrams consistently
364         * coming from the same IP.
365         * We would like to connect the socket, but since peer's
366         * UDP code can be less perfect than ours, _peer's_ IP:port
367         * in replies may differ from IP:port we used to send
368         * our first packet. We can connect() only when we get
369         * first reply. */
370
371        /* build opcode */
372        opcode = TFTP_WRQ;
373        if (CMD_GET(option_mask32)) {
374            opcode = TFTP_RRQ;
375        }
376        /* add filename and mode */
377        /* fill in packet if the filename fits into xbuf */
378        len = strlen(remote_file) + 1;
379        if (2 + len + sizeof("octet") >= io_bufsize) {
380            bb_error_msg("remote filename is too long");
381            goto ret;
382        }
383        strcpy(cp, remote_file);
384        cp += len;
385        /* add "mode" part of the packet */
386        strcpy(cp, "octet");
387        cp += sizeof("octet");
388
389# if ENABLE_FEATURE_TFTP_BLOCKSIZE
390        if (blksize == TFTP_BLKSIZE_DEFAULT && !want_transfer_size)
391            goto send_pkt;
392
393        /* Need to add option to pkt */
394        if ((&xbuf[io_bufsize - 1] - cp) < sizeof("blksize NNNNN tsize ") + sizeof(off_t)*3) {
395            bb_error_msg("remote filename is too long");
396            goto ret;
397        }
398        expect_OACK = 1;
399# endif
400#endif /* ENABLE_TFTP */
401
402#if ENABLE_FEATURE_TFTP_BLOCKSIZE
403 add_blksize_opt:
404        if (blksize != TFTP_BLKSIZE_DEFAULT) {
405            /* add "blksize", <nul>, blksize, <nul> */
406            strcpy(cp, "blksize");
407            cp += sizeof("blksize");
408            cp += snprintf(cp, 6, "%d", blksize) + 1;
409        }
410        if (want_transfer_size) {
411            /* add "tsize", <nul>, size, <nul> (see RFC2349) */
412            /* if tftp and downloading, we send "0" (since we opened local_fd with O_TRUNC)
413             * and this makes server to send "tsize" option with the size */
414            /* if tftp and uploading, we send file size (maybe dont, to not confuse old servers???) */
415            /* if tftpd and downloading, we are answering to client's request */
416            /* if tftpd and uploading: !want_transfer_size, this code is not executed */
417            struct stat st;
418            strcpy(cp, "tsize");
419            cp += sizeof("tsize");
420            st.st_size = 0;
421            fstat(local_fd, &st);
422            cp += sprintf(cp, "%"OFF_FMT"u", (off_t)st.st_size) + 1;
423# if ENABLE_FEATURE_TFTP_PROGRESS_BAR
424            /* Save for progress bar. If 0 (tftp downloading),
425             * we look at server's reply later */
426            G.size = st.st_size;
427            if (remote_file && st.st_size)
428                tftp_progress_init();
429# endif
430        }
431#endif
432        /* First packet is built, so skip packet generation */
433        goto send_pkt;
434    }
435
436    /* Using mostly goto's - continue/break will be less clear
437     * in where we actually jump to */
438    while (1) {
439        /* Build ACK or DATA */
440        cp = xbuf + 2;
441        *((uint16_t*)cp) = htons(block_nr);
442        cp += 2;
443        block_nr++;
444        opcode = TFTP_ACK;
445        if (CMD_PUT(option_mask32)) {
446            opcode = TFTP_DATA;
447            len = full_read(local_fd, cp, blksize);
448            if (len < 0) {
449                goto send_read_err_pkt;
450            }
451            if (len != blksize) {
452                finished = 1;
453            }
454            cp += len;
455            IF_FEATURE_TFTP_PROGRESS_BAR(G.pos += len;)
456        }
457 send_pkt:
458        /* Send packet */
459        *((uint16_t*)xbuf) = htons(opcode); /* fill in opcode part */
460        send_len = cp - xbuf;
461        /* NB: send_len value is preserved in code below
462         * for potential resend */
463
464        retries = TFTP_NUM_RETRIES;  /* re-initialize */
465        waittime_ms = TFTP_TIMEOUT_MS;
466
467 send_again:
468#if ENABLE_TFTP_DEBUG
469        fprintf(stderr, "sending %u bytes\n", send_len);
470        for (cp = xbuf; cp < &xbuf[send_len]; cp++)
471            fprintf(stderr, "%02x ", (unsigned char) *cp);
472        fprintf(stderr, "\n");
473#endif
474        xsendto(socket_fd, xbuf, send_len, &peer_lsa->u.sa, peer_lsa->len);
475
476#if ENABLE_FEATURE_TFTP_PROGRESS_BAR
477        if (is_bb_progress_inited(&G.pmt))
478            tftp_progress_update();
479#endif
480        /* Was it final ACK? then exit */
481        if (finished && (opcode == TFTP_ACK))
482            goto ret;
483
484 recv_again:
485        /* Receive packet */
486        /*pfd[0].fd = socket_fd;*/
487        pfd[0].events = POLLIN;
488        switch (safe_poll(pfd, 1, waittime_ms)) {
489        default:
490            /*bb_perror_msg("poll"); - done in safe_poll */
491            goto ret;
492        case 0:
493            retries--;
494            if (retries == 0) {
495                tftp_progress_done();
496                bb_error_msg("timeout");
497                goto ret; /* no err packet sent */
498            }
499
500            /* exponential backoff with limit */
501            waittime_ms += waittime_ms/2;
502            if (waittime_ms > TFTP_MAXTIMEOUT_MS) {
503                waittime_ms = TFTP_MAXTIMEOUT_MS;
504            }
505
506            goto send_again; /* resend last sent pkt */
507        case 1:
508            if (!our_lsa) {
509                /* tftp (not tftpd!) receiving 1st packet */
510                our_lsa = ((void*)(ptrdiff_t)-1); /* not NULL */
511                len = recvfrom(socket_fd, rbuf, io_bufsize, 0,
512                        &peer_lsa->u.sa, &peer_lsa->len);
513                /* Our first dgram went to port 69
514                 * but reply may come from different one.
515                 * Remember and use this new port (and IP) */
516                if (len >= 0)
517                    xconnect(socket_fd, &peer_lsa->u.sa, peer_lsa->len);
518            } else {
519                /* tftpd, or not the very first packet:
520                 * socket is connect()ed, can just read from it. */
521                /* Don't full_read()!
522                 * This is not TCP, one read == one pkt! */
523                len = safe_read(socket_fd, rbuf, io_bufsize);
524            }
525            if (len < 0) {
526                goto send_read_err_pkt;
527            }
528            if (len < 4) { /* too small? */
529                goto recv_again;
530            }
531        }
532
533        /* Process recv'ed packet */
534        opcode = ntohs( ((uint16_t*)rbuf)[0] );
535        recv_blk = ntohs( ((uint16_t*)rbuf)[1] );
536#if ENABLE_TFTP_DEBUG
537        fprintf(stderr, "received %d bytes: %04x %04x\n", len, opcode, recv_blk);
538#endif
539        if (opcode == TFTP_ERROR) {
540            static const char errcode_str[] ALIGN1 =
541                "\0"
542                "file not found\0"
543                "access violation\0"
544                "disk full\0"
545                "bad operation\0"
546                "unknown transfer id\0"
547                "file already exists\0"
548                "no such user\0"
549                "bad option";
550
551            const char *msg = "";
552
553            if (len > 4 && rbuf[4] != '\0') {
554                msg = &rbuf[4];
555                rbuf[io_bufsize - 1] = '\0'; /* paranoia */
556            } else if (recv_blk <= 8) {
557                msg = nth_string(errcode_str, recv_blk);
558            }
559            bb_error_msg("server error: (%u) %s", recv_blk, msg);
560            goto ret;
561        }
562
563#if ENABLE_FEATURE_TFTP_BLOCKSIZE
564        if (expect_OACK) {
565            expect_OACK = 0;
566            if (opcode == TFTP_OACK) {
567                /* server seems to support options */
568                char *res;
569
570                res = tftp_get_option("blksize", &rbuf[2], len - 2);
571                if (res) {
572                    blksize = tftp_blksize_check(res, blksize);
573                    if (blksize < 0) {
574                        G_error_pkt_reason = ERR_BAD_OPT;
575                        goto send_err_pkt;
576                    }
577                    io_bufsize = blksize + 4;
578                }
579# if ENABLE_FEATURE_TFTP_PROGRESS_BAR
580                if (remote_file && G.size == 0) { /* if we don't know it yet */
581                    res = tftp_get_option("tsize", &rbuf[2], len - 2);
582                    if (res) {
583                        G.size = bb_strtoull(res, NULL, 10);
584                        if (G.size)
585                            tftp_progress_init();
586                    }
587                }
588# endif
589                if (CMD_GET(option_mask32)) {
590                    /* We'll send ACK for OACK,
591                     * such ACK has "block no" of 0 */
592                    block_nr = 0;
593                }
594                continue;
595            }
596            /* rfc2347:
597             * "An option not acknowledged by the server
598             * must be ignored by the client and server
599             * as if it were never requested." */
600            if (blksize != TFTP_BLKSIZE_DEFAULT)
601                bb_error_msg("falling back to blocksize "TFTP_BLKSIZE_DEFAULT_STR);
602            blksize = TFTP_BLKSIZE_DEFAULT;
603            io_bufsize = TFTP_BLKSIZE_DEFAULT + 4;
604        }
605#endif
606        /* block_nr is already advanced to next block# we expect
607         * to get / block# we are about to send next time */
608
609        if (CMD_GET(option_mask32) && (opcode == TFTP_DATA)) {
610            if (recv_blk == block_nr) {
611                int sz = full_write(local_fd, &rbuf[4], len - 4);
612                if (sz != len - 4) {
613                    strcpy(G_error_pkt_str, bb_msg_write_error);
614                    G_error_pkt_reason = ERR_WRITE;
615                    goto send_err_pkt;
616                }
617                if (sz != blksize) {
618                    finished = 1;
619                }
620                IF_FEATURE_TFTP_PROGRESS_BAR(G.pos += sz;)
621                continue; /* send ACK */
622            }
623/* Disabled to cope with servers with Sorcerer's Apprentice Syndrome */
624#if 0
625            if (recv_blk == (block_nr - 1)) {
626                /* Server lost our TFTP_ACK.  Resend it */
627                block_nr = recv_blk;
628                continue;
629            }
630#endif
631        }
632
633        if (CMD_PUT(option_mask32) && (opcode == TFTP_ACK)) {
634            /* did peer ACK our last DATA pkt? */
635            if (recv_blk == (uint16_t) (block_nr - 1)) {
636                if (finished)
637                    goto ret;
638                continue; /* send next block */
639            }
640        }
641        /* Awww... recv'd packet is not recognized! */
642        goto recv_again;
643        /* why recv_again? - rfc1123 says:
644         * "The sender (i.e., the side originating the DATA packets)
645         *  must never resend the current DATA packet on receipt
646         *  of a duplicate ACK".
647         * DATA pkts are resent ONLY on timeout.
648         * Thus "goto send_again" will ba a bad mistake above.
649         * See:
650         * http://en.wikipedia.org/wiki/Sorcerer's_Apprentice_Syndrome
651         */
652    } /* end of "while (1)" */
653 ret:
654    if (ENABLE_FEATURE_CLEAN_UP) {
655        close(local_fd);
656        close(socket_fd);
657        free(xbuf);
658        free(rbuf);
659    }
660    return finished == 0; /* returns 1 on failure */
661
662 send_read_err_pkt:
663    strcpy(G_error_pkt_str, bb_msg_read_error);
664 send_err_pkt:
665    if (G_error_pkt_str[0])
666        bb_error_msg("%s", G_error_pkt_str);
667    G.error_pkt[1] = TFTP_ERROR;
668    xsendto(socket_fd, G.error_pkt, 4 + 1 + strlen(G_error_pkt_str),
669            &peer_lsa->u.sa, peer_lsa->len);
670    return EXIT_FAILURE;
671#undef remote_file
672}
673
674#if ENABLE_TFTP
675
676int tftp_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
677int tftp_main(int argc UNUSED_PARAM, char **argv)
678{
679    len_and_sockaddr *peer_lsa;
680    const char *local_file = NULL;
681    const char *remote_file = NULL;
682# if ENABLE_FEATURE_TFTP_BLOCKSIZE
683    const char *blksize_str = TFTP_BLKSIZE_DEFAULT_STR;
684    int blksize;
685# endif
686    int result;
687    int port;
688    IF_GETPUT(int opt;)
689
690    INIT_G();
691
692    /* -p or -g is mandatory, and they are mutually exclusive */
693    opt_complementary = "" IF_FEATURE_TFTP_GET("g:") IF_FEATURE_TFTP_PUT("p:")
694            IF_GETPUT("g--p:p--g:");
695
696    IF_GETPUT(opt =) getopt32(argv,
697            IF_FEATURE_TFTP_GET("g") IF_FEATURE_TFTP_PUT("p")
698                "l:r:" IF_FEATURE_TFTP_BLOCKSIZE("b:"),
699            &local_file, &remote_file
700            IF_FEATURE_TFTP_BLOCKSIZE(, &blksize_str));
701    argv += optind;
702
703# if ENABLE_FEATURE_TFTP_BLOCKSIZE
704    /* Check if the blksize is valid:
705     * RFC2348 says between 8 and 65464 */
706    blksize = tftp_blksize_check(blksize_str, 65564);
707    if (blksize < 0) {
708        //bb_error_msg("bad block size");
709        return EXIT_FAILURE;
710    }
711# endif
712
713    if (remote_file) {
714        if (!local_file) {
715            const char *slash = strrchr(remote_file, '/');
716            local_file = slash ? slash + 1 : remote_file;
717        }
718    } else {
719        remote_file = local_file;
720    }
721
722    /* Error if filename or host is not known */
723    if (!remote_file || !argv[0])
724        bb_show_usage();
725
726    port = bb_lookup_port(argv[1], "udp", 69);
727    peer_lsa = xhost2sockaddr(argv[0], port);
728
729# if ENABLE_TFTP_DEBUG
730    fprintf(stderr, "using server '%s', remote_file '%s', local_file '%s'\n",
731            xmalloc_sockaddr2dotted(&peer_lsa->u.sa),
732            remote_file, local_file);
733# endif
734
735# if ENABLE_FEATURE_TFTP_PROGRESS_BAR
736    G.file = remote_file;
737# endif
738    result = tftp_protocol(
739        NULL /*our_lsa*/, peer_lsa,
740        local_file, remote_file
741        IF_FEATURE_TFTP_BLOCKSIZE(, 1 /* want_transfer_size */)
742        IF_FEATURE_TFTP_BLOCKSIZE(, blksize)
743    );
744    tftp_progress_done();
745
746    if (result != EXIT_SUCCESS && NOT_LONE_DASH(local_file) && CMD_GET(opt)) {
747        unlink(local_file);
748    }
749    return result;
750}
751
752#endif /* ENABLE_TFTP */
753
754#if ENABLE_TFTPD
755int tftpd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
756int tftpd_main(int argc UNUSED_PARAM, char **argv)
757{
758    len_and_sockaddr *our_lsa;
759    len_and_sockaddr *peer_lsa;
760    char *local_file, *mode, *user_opt;
761    const char *error_msg;
762    int opt, result, opcode;
763    IF_FEATURE_TFTP_BLOCKSIZE(int blksize = TFTP_BLKSIZE_DEFAULT;)
764    IF_FEATURE_TFTP_BLOCKSIZE(int want_transfer_size = 0;)
765
766    INIT_G();
767
768    our_lsa = get_sock_lsa(STDIN_FILENO);
769    if (!our_lsa) {
770        /* This is confusing:
771         *bb_error_msg_and_die("stdin is not a socket");
772         * Better: */
773        bb_show_usage();
774        /* Help text says that tftpd must be used as inetd service,
775         * which is by far the most usual cause of get_sock_lsa
776         * failure */
777    }
778    peer_lsa = xzalloc(LSA_LEN_SIZE + our_lsa->len);
779    peer_lsa->len = our_lsa->len;
780
781    /* Shifting to not collide with TFTP_OPTs */
782    opt = option_mask32 = TFTPD_OPT | (getopt32(argv, "rcu:l", &user_opt) << 8);
783    argv += optind;
784    if (opt & TFTPD_OPT_l) {
785        openlog(applet_name, LOG_PID, LOG_DAEMON);
786        logmode = LOGMODE_SYSLOG;
787    }
788    if (opt & TFTPD_OPT_u) {
789        /* Must be before xchroot */
790        G.pw = xgetpwnam(user_opt);
791    }
792    if (argv[0]) {
793        xchroot(argv[0]);
794    }
795
796    result = recv_from_to(STDIN_FILENO, G.block_buf, sizeof(G.block_buf),
797            0 /* flags */,
798            &peer_lsa->u.sa, &our_lsa->u.sa, our_lsa->len);
799
800    error_msg = "malformed packet";
801    opcode = ntohs(*(uint16_t*)G.block_buf);
802    if (result < 4 || result >= sizeof(G.block_buf)
803     || G.block_buf[result-1] != '\0'
804     || (IF_FEATURE_TFTP_PUT(opcode != TFTP_RRQ) /* not download */
805         IF_GETPUT(&&)
806         IF_FEATURE_TFTP_GET(opcode != TFTP_WRQ) /* not upload */
807        )
808    ) {
809        goto err;
810    }
811    local_file = G.block_buf + 2;
812    if (local_file[0] == '.' || strstr(local_file, "/.")) {
813        error_msg = "dot in file name";
814        goto err;
815    }
816    mode = local_file + strlen(local_file) + 1;
817    /* RFC 1350 says mode string is case independent */
818    if (mode >= G.block_buf + result || strcasecmp(mode, "octet") != 0) {
819        goto err;
820    }
821# if ENABLE_FEATURE_TFTP_BLOCKSIZE
822    {
823        char *res;
824        char *opt_str = mode + sizeof("octet");
825        int opt_len = G.block_buf + result - opt_str;
826        if (opt_len > 0) {
827            res = tftp_get_option("blksize", opt_str, opt_len);
828            if (res) {
829                blksize = tftp_blksize_check(res, 65564);
830                if (blksize < 0) {
831                    G_error_pkt_reason = ERR_BAD_OPT;
832                    /* will just send error pkt */
833                    goto do_proto;
834                }
835            }
836            if (opcode != TFTP_WRQ /* download? */
837            /* did client ask us about file size? */
838             && tftp_get_option("tsize", opt_str, opt_len)
839            ) {
840                want_transfer_size = 1;
841            }
842        }
843    }
844# endif
845
846    if (!ENABLE_FEATURE_TFTP_PUT || opcode == TFTP_WRQ) {
847        if (opt & TFTPD_OPT_r) {
848            /* This would mean "disk full" - not true */
849            /*G_error_pkt_reason = ERR_WRITE;*/
850            error_msg = bb_msg_write_error;
851            goto err;
852        }
853        IF_GETPUT(option_mask32 |= TFTP_OPT_GET;) /* will receive file's data */
854    } else {
855        IF_GETPUT(option_mask32 |= TFTP_OPT_PUT;) /* will send file's data */
856    }
857
858    /* NB: if G_error_pkt_str or G_error_pkt_reason is set up,
859     * tftp_protocol() just sends one error pkt and returns */
860
861 do_proto:
862    close(STDIN_FILENO); /* close old, possibly wildcard socket */
863    /* tftp_protocol() will create new one, bound to particular local IP */
864    result = tftp_protocol(
865        our_lsa, peer_lsa,
866        local_file IF_TFTP(, NULL /*remote_file*/)
867        IF_FEATURE_TFTP_BLOCKSIZE(, want_transfer_size)
868        IF_FEATURE_TFTP_BLOCKSIZE(, blksize)
869    );
870
871    return result;
872 err:
873    strcpy(G_error_pkt_str, error_msg);
874    goto do_proto;
875}
876
877#endif /* ENABLE_TFTPD */
878
879#endif /* ENABLE_FEATURE_TFTP_GET || ENABLE_FEATURE_TFTP_PUT */
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