source: MondoRescue/branches/3.3/mindi-busybox/networking/tftp.c@ 3621

/* vi: set sw=4 ts=4: */
/*
 * A simple tftp client/server for busybox.
 * Tries to follow RFC1350.
 * Only "octet" mode supported.
 * Optional blocksize negotiation (RFC2347 + RFC2348)
 *
 * Copyright (C) 2001 Magnus Damm <damm@opensource.se>
 *
 * Parts of the code based on:
 *
 * atftp:  Copyright (C) 2000 Jean-Pierre Lefebvre <helix@step.polymtl.ca>
 *                        and Remi Lefebvre <remi@debian.org>
 *
 * utftp:  Copyright (C) 1999 Uwe Ohse <uwe@ohse.de>
 *
 * tftpd added by Denys Vlasenko & Vladimir Dronnikov
 *
 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
 */

//usage:#define tftp_trivial_usage
//usage:       "[OPTIONS] HOST [PORT]"
//usage:#define tftp_full_usage "\n\n"
//usage:       "Transfer a file from/to tftp server\n"
//usage:     "\n    -l FILE Local FILE"
//usage:     "\n    -r FILE Remote FILE"
//usage:    IF_FEATURE_TFTP_GET(
//usage:     "\n    -g  Get file"
//usage:    )
//usage:    IF_FEATURE_TFTP_PUT(
//usage:     "\n    -p  Put file"
//usage:    )
//usage:    IF_FEATURE_TFTP_BLOCKSIZE(
//usage:     "\n    -b SIZE Transfer blocks of SIZE octets"
//usage:    )
//usage:
//usage:#define tftpd_trivial_usage
//usage:       "[-cr] [-u USER] [DIR]"
//usage:#define tftpd_full_usage "\n\n"
//usage:       "Transfer a file on tftp client's request\n"
//usage:       "\n"
//usage:       "tftpd should be used as an inetd service.\n"
//usage:       "tftpd's line for inetd.conf:\n"
//usage:       "    69 dgram udp nowait root tftpd tftpd -l /files/to/serve\n"
//usage:       "It also can be ran from udpsvd:\n"
//usage:       "    udpsvd -vE 0.0.0.0 69 tftpd /files/to/serve\n"
//usage:     "\n    -r  Prohibit upload"
//usage:     "\n    -c  Allow file creation via upload"
//usage:     "\n    -u  Access files as USER"
//usage:     "\n    -l  Log to syslog (inetd mode requires this)"

#include "libbb.h"
#include "common_bufsiz.h"
#include <syslog.h>

#if ENABLE_FEATURE_TFTP_GET || ENABLE_FEATURE_TFTP_PUT

#define TFTP_BLKSIZE_DEFAULT       512  /* according to RFC 1350, don't change */
#define TFTP_BLKSIZE_DEFAULT_STR "512"
/* Was 50 ms but users asked to bump it up a bit */
#define TFTP_TIMEOUT_MS            100
#define TFTP_MAXTIMEOUT_MS        2000
#define TFTP_NUM_RETRIES            12  /* number of backed-off retries */

/* opcodes we support */
#define TFTP_RRQ   1
#define TFTP_WRQ   2
#define TFTP_DATA  3
#define TFTP_ACK   4
#define TFTP_ERROR 5
#define TFTP_OACK  6

/* error codes sent over network (we use only 0, 1, 3 and 8) */
/* generic (error message is included in the packet) */
#define ERR_UNSPEC   0
#define ERR_NOFILE   1
#define ERR_ACCESS   2
/* disk full or allocation exceeded */
#define ERR_WRITE    3
#define ERR_OP       4
#define ERR_BAD_ID   5
#define ERR_EXIST    6
#define ERR_BAD_USER 7
#define ERR_BAD_OPT  8

/* masks coming from getopt32 */
enum {
    TFTP_OPT_GET = (1 << 0),
    TFTP_OPT_PUT = (1 << 1),
    /* pseudo option: if set, it's tftpd */
    TFTPD_OPT = (1 << 7) * ENABLE_TFTPD,
    TFTPD_OPT_r = (1 << 8) * ENABLE_TFTPD,
    TFTPD_OPT_c = (1 << 9) * ENABLE_TFTPD,
    TFTPD_OPT_u = (1 << 10) * ENABLE_TFTPD,
    TFTPD_OPT_l = (1 << 11) * ENABLE_TFTPD,
};

#if ENABLE_FEATURE_TFTP_GET && !ENABLE_FEATURE_TFTP_PUT
#define IF_GETPUT(...)
#define CMD_GET(cmd) 1
#define CMD_PUT(cmd) 0
#elif !ENABLE_FEATURE_TFTP_GET && ENABLE_FEATURE_TFTP_PUT
#define IF_GETPUT(...)
#define CMD_GET(cmd) 0
#define CMD_PUT(cmd) 1
#else
#define IF_GETPUT(...) __VA_ARGS__
#define CMD_GET(cmd) ((cmd) & TFTP_OPT_GET)
#define CMD_PUT(cmd) ((cmd) & TFTP_OPT_PUT)
#endif
/* NB: in the code below
 * CMD_GET(cmd) and CMD_PUT(cmd) are mutually exclusive
 */


struct globals {
    /* u16 TFTP_ERROR; u16 reason; both network-endian, then error text: */
    uint8_t error_pkt[4 + 32];
    struct passwd *pw;
    /* Used in tftpd_main() for initial packet */
    /* Some HP PA-RISC firmware always sends fixed 516-byte requests */
    char block_buf[516];
    char block_buf_tail[1];
#if ENABLE_FEATURE_TFTP_PROGRESS_BAR
    off_t pos;
    off_t size;
    const char *file;
    bb_progress_t pmt;
#endif
} FIX_ALIASING;
#define G (*(struct globals*)bb_common_bufsiz1)
#define INIT_G() do { \
    setup_common_bufsiz(); \
    BUILD_BUG_ON(sizeof(G) > COMMON_BUFSIZE); \
} while (0)

#define G_error_pkt_reason (G.error_pkt[3])
#define G_error_pkt_str    ((char*)(G.error_pkt + 4))

#if ENABLE_FEATURE_TFTP_PROGRESS_BAR
static void tftp_progress_update(void)
{
    bb_progress_update(&G.pmt, 0, G.pos, G.size);
}
static void tftp_progress_init(void)
{
    bb_progress_init(&G.pmt, G.file);
    tftp_progress_update();
}
static void tftp_progress_done(void)
{
    if (is_bb_progress_inited(&G.pmt)) {
        tftp_progress_update();
        bb_putchar_stderr('\n');
        bb_progress_free(&G.pmt);
    }
}
#else
# define tftp_progress_init() ((void)0)
# define tftp_progress_done() ((void)0)
#endif

#if ENABLE_FEATURE_TFTP_BLOCKSIZE

static int tftp_blksize_check(const char *blksize_str, int maxsize)
{
    /* Check if the blksize is valid:
     * RFC2348 says between 8 and 65464,
     * but our implementation makes it impossible
     * to use blksizes smaller than 22 octets. */
    unsigned blksize = bb_strtou(blksize_str, NULL, 10);
    if (errno
     || (blksize < 24) || (blksize > maxsize)
    ) {
        bb_error_msg("bad blocksize '%s'", blksize_str);
        return -1;
    }
# if ENABLE_TFTP_DEBUG
    bb_error_msg("using blksize %u", blksize);
# endif
    return blksize;
}

static char *tftp_get_option(const char *option, char *buf, int len)
{
    int opt_val = 0;
    int opt_found = 0;
    int k;

    /* buf points to:
     * "opt_name<NUL>opt_val<NUL>opt_name2<NUL>opt_val2<NUL>..." */

    while (len > 0) {
        /* Make sure options are terminated correctly */
        for (k = 0; k < len; k++) {
            if (buf[k] == '\0') {
                goto nul_found;
            }
        }
        return NULL;
 nul_found:
        if (opt_val == 0) { /* it's "name" part */
            if (strcasecmp(buf, option) == 0) {
                opt_found = 1;
            }
        } else if (opt_found) {
            return buf;
        }

        k++;
        buf += k;
        len -= k;
        opt_val ^= 1;
    }

    return NULL;
}

#endif

static int tftp_protocol(
        /* NULL if tftp, !NULL if tftpd: */
        len_and_sockaddr *our_lsa,
        len_and_sockaddr *peer_lsa,
        const char *local_file
        IF_TFTP(, const char *remote_file)
#if !ENABLE_TFTP
# define remote_file NULL
#endif
        /* 1 for tftp; 1/0 for tftpd depending whether client asked about it: */
        IF_FEATURE_TFTP_BLOCKSIZE(, int want_transfer_size)
        IF_FEATURE_TFTP_BLOCKSIZE(, int blksize))
{
#if !ENABLE_FEATURE_TFTP_BLOCKSIZE
    enum { blksize = TFTP_BLKSIZE_DEFAULT };
#endif

    struct pollfd pfd[1];
#define socket_fd (pfd[0].fd)
    int len;
    int send_len;
    IF_FEATURE_TFTP_BLOCKSIZE(smallint expect_OACK = 0;)
    smallint finished = 0;
    uint16_t opcode;
    uint16_t block_nr;
    uint16_t recv_blk;
    int open_mode, local_fd;
    int retries, waittime_ms;
    int io_bufsize = blksize + 4;
    char *cp;
    /* Can't use RESERVE_CONFIG_BUFFER here since the allocation
     * size varies meaning BUFFERS_GO_ON_STACK would fail.
     *
     * We must keep the transmit and receive buffers separate
     * in case we rcv a garbage pkt - we need to rexmit the last pkt.
     */
    char *xbuf = xmalloc(io_bufsize);
    char *rbuf = xmalloc(io_bufsize);

    socket_fd = xsocket(peer_lsa->u.sa.sa_family, SOCK_DGRAM, 0);
    setsockopt_reuseaddr(socket_fd);

    if (!ENABLE_TFTP || our_lsa) { /* tftpd */
        /* Create a socket which is:
         * 1. bound to IP:port peer sent 1st datagram to,
         * 2. connected to peer's IP:port
         * This way we will answer from the IP:port peer
         * expects, will not get any other packets on
         * the socket, and also plain read/write will work. */
        xbind(socket_fd, &our_lsa->u.sa, our_lsa->len);
        xconnect(socket_fd, &peer_lsa->u.sa, peer_lsa->len);

        /* Is there an error already? Send pkt and bail out */
        if (G_error_pkt_reason || G_error_pkt_str[0])
            goto send_err_pkt;

        if (G.pw) {
            change_identity(G.pw); /* initgroups, setgid, setuid */
        }
    }

    /* Prepare open mode */
    if (CMD_PUT(option_mask32)) {
        open_mode = O_RDONLY;
    } else {
        open_mode = O_WRONLY | O_TRUNC | O_CREAT;
#if ENABLE_TFTPD
        if ((option_mask32 & (TFTPD_OPT+TFTPD_OPT_c)) == TFTPD_OPT) {
            /* tftpd without -c */
            open_mode = O_WRONLY | O_TRUNC;
        }
#endif
    }

    /* Examples of network traffic.
     * Note two cases when ACKs with block# of 0 are sent.
     *
     * Download without options:
     * tftp -> "\0\1FILENAME\0octet\0"
     *         "\0\3\0\1FILEDATA..." <- tftpd
     * tftp -> "\0\4\0\1"
     * ...
     * Download with option of blksize 16384:
     * tftp -> "\0\1FILENAME\0octet\0blksize\00016384\0"
     *         "\0\6blksize\00016384\0" <- tftpd
     * tftp -> "\0\4\0\0"
     *         "\0\3\0\1FILEDATA..." <- tftpd
     * tftp -> "\0\4\0\1"
     * ...
     * Upload without options:
     * tftp -> "\0\2FILENAME\0octet\0"
     *         "\0\4\0\0" <- tftpd
     * tftp -> "\0\3\0\1FILEDATA..."
     *         "\0\4\0\1" <- tftpd
     * ...
     * Upload with option of blksize 16384:
     * tftp -> "\0\2FILENAME\0octet\0blksize\00016384\0"
     *         "\0\6blksize\00016384\0" <- tftpd
     * tftp -> "\0\3\0\1FILEDATA..."
     *         "\0\4\0\1" <- tftpd
     * ...
     */
    block_nr = 1;
    cp = xbuf + 2;

    if (!ENABLE_TFTP || our_lsa) { /* tftpd */
        /* Open file (must be after changing user) */
        local_fd = open(local_file, open_mode, 0666);
        if (local_fd < 0) {
            G_error_pkt_reason = ERR_NOFILE;
            strcpy(G_error_pkt_str, "can't open file");
            goto send_err_pkt;
        }
/* gcc 4.3.1 would NOT optimize it out as it should! */
#if ENABLE_FEATURE_TFTP_BLOCKSIZE
        if (blksize != TFTP_BLKSIZE_DEFAULT || want_transfer_size) {
            /* Create and send OACK packet. */
            /* For the download case, block_nr is still 1 -
             * we expect 1st ACK from peer to be for (block_nr-1),
             * that is, for "block 0" which is our OACK pkt */
            opcode = TFTP_OACK;
            goto add_blksize_opt;
        }
#endif
        if (CMD_GET(option_mask32)) {
            /* It's upload and we don't send OACK.
             * We must ACK 1st packet (with filename)
             * as if it is "block 0" */
            block_nr = 0;
        }
    } else { /* tftp */
        /* Open file (must be after changing user) */
        local_fd = CMD_GET(option_mask32) ? STDOUT_FILENO : STDIN_FILENO;
        if (NOT_LONE_DASH(local_file))
            local_fd = xopen(local_file, open_mode);
/* Removing #if, or using if() statement instead of #if may lead to
 * "warning: null argument where non-null required": */
#if ENABLE_TFTP
        /* tftp */

        /* We can't (and don't really need to) bind the socket:
         * we don't know from which local IP datagrams will be sent,
         * but kernel will pick the same IP every time (unless routing
         * table is changed), thus peer will see dgrams consistently
         * coming from the same IP.
         * We would like to connect the socket, but since peer's
         * UDP code can be less perfect than ours, _peer's_ IP:port
         * in replies may differ from IP:port we used to send
         * our first packet. We can connect() only when we get
         * first reply. */

        /* build opcode */
        opcode = TFTP_WRQ;
        if (CMD_GET(option_mask32)) {
            opcode = TFTP_RRQ;
        }
        /* add filename and mode */
        /* fill in packet if the filename fits into xbuf */
        len = strlen(remote_file) + 1;
        if (2 + len + sizeof("octet") >= io_bufsize) {
            bb_error_msg("remote filename is too long");
            goto ret;
        }
        strcpy(cp, remote_file);
        cp += len;
        /* add "mode" part of the packet */
        strcpy(cp, "octet");
        cp += sizeof("octet");

# if ENABLE_FEATURE_TFTP_BLOCKSIZE
        if (blksize == TFTP_BLKSIZE_DEFAULT && !want_transfer_size)
            goto send_pkt;

        /* Need to add option to pkt */
        if ((&xbuf[io_bufsize - 1] - cp) < sizeof("blksize NNNNN tsize ") + sizeof(off_t)*3) {
            bb_error_msg("remote filename is too long");
            goto ret;
        }
        expect_OACK = 1;
# endif
#endif /* ENABLE_TFTP */

#if ENABLE_FEATURE_TFTP_BLOCKSIZE
 add_blksize_opt:
        if (blksize != TFTP_BLKSIZE_DEFAULT) {
            /* add "blksize", <nul>, blksize, <nul> */
            strcpy(cp, "blksize");
            cp += sizeof("blksize");
            cp += snprintf(cp, 6, "%d", blksize) + 1;
        }
        if (want_transfer_size) {
            /* add "tsize", <nul>, size, <nul> (see RFC2349) */
            /* if tftp and downloading, we send "0" (since we opened local_fd with O_TRUNC)
             * and this makes server to send "tsize" option with the size */
            /* if tftp and uploading, we send file size (maybe dont, to not confuse old servers???) */
            /* if tftpd and downloading, we are answering to client's request */
            /* if tftpd and uploading: !want_transfer_size, this code is not executed */
            struct stat st;
            strcpy(cp, "tsize");
            cp += sizeof("tsize");
            st.st_size = 0;
            fstat(local_fd, &st);
            cp += sprintf(cp, "%"OFF_FMT"u", (off_t)st.st_size) + 1;
# if ENABLE_FEATURE_TFTP_PROGRESS_BAR
            /* Save for progress bar. If 0 (tftp downloading),
             * we look at server's reply later */
            G.size = st.st_size;
            if (remote_file && st.st_size)
                tftp_progress_init();
# endif
        }
#endif
        /* First packet is built, so skip packet generation */
        goto send_pkt;
    }

    /* Using mostly goto's - continue/break will be less clear
     * in where we actually jump to */
    while (1) {
        /* Build ACK or DATA */
        cp = xbuf + 2;
        *((uint16_t*)cp) = htons(block_nr);
        cp += 2;
        block_nr++;
        opcode = TFTP_ACK;
        if (CMD_PUT(option_mask32)) {
            opcode = TFTP_DATA;
            len = full_read(local_fd, cp, blksize);
            if (len < 0) {
                goto send_read_err_pkt;
            }
            if (len != blksize) {
                finished = 1;
            }
            cp += len;
            IF_FEATURE_TFTP_PROGRESS_BAR(G.pos += len;)
        }
 send_pkt:
        /* Send packet */
        *((uint16_t*)xbuf) = htons(opcode); /* fill in opcode part */
        send_len = cp - xbuf;
        /* NB: send_len value is preserved in code below
         * for potential resend */

        retries = TFTP_NUM_RETRIES;  /* re-initialize */
        waittime_ms = TFTP_TIMEOUT_MS;

 send_again:
#if ENABLE_TFTP_DEBUG
        fprintf(stderr, "sending %u bytes\n", send_len);
        for (cp = xbuf; cp < &xbuf[send_len]; cp++)
            fprintf(stderr, "%02x ", (unsigned char) *cp);
        fprintf(stderr, "\n");
#endif
        xsendto(socket_fd, xbuf, send_len, &peer_lsa->u.sa, peer_lsa->len);

#if ENABLE_FEATURE_TFTP_PROGRESS_BAR
        if (is_bb_progress_inited(&G.pmt))
            tftp_progress_update();
#endif
        /* Was it final ACK? then exit */
        if (finished && (opcode == TFTP_ACK))
            goto ret;

 recv_again:
        /* Receive packet */
        /*pfd[0].fd = socket_fd;*/
        pfd[0].events = POLLIN;
        switch (safe_poll(pfd, 1, waittime_ms)) {
        default:
            /*bb_perror_msg("poll"); - done in safe_poll */
            goto ret;
        case 0:
            retries--;
            if (retries == 0) {
                tftp_progress_done();
                bb_error_msg("timeout");
                goto ret; /* no err packet sent */
            }

            /* exponential backoff with limit */
            waittime_ms += waittime_ms/2;
            if (waittime_ms > TFTP_MAXTIMEOUT_MS) {
                waittime_ms = TFTP_MAXTIMEOUT_MS;
            }

            goto send_again; /* resend last sent pkt */
        case 1:
            if (!our_lsa) {
                /* tftp (not tftpd!) receiving 1st packet */
                our_lsa = ((void*)(ptrdiff_t)-1); /* not NULL */
                len = recvfrom(socket_fd, rbuf, io_bufsize, 0,
                        &peer_lsa->u.sa, &peer_lsa->len);
                /* Our first dgram went to port 69
                 * but reply may come from different one.
                 * Remember and use this new port (and IP) */
                if (len >= 0)
                    xconnect(socket_fd, &peer_lsa->u.sa, peer_lsa->len);
            } else {
                /* tftpd, or not the very first packet:
                 * socket is connect()ed, can just read from it. */
                /* Don't full_read()!
                 * This is not TCP, one read == one pkt! */
                len = safe_read(socket_fd, rbuf, io_bufsize);
            }
            if (len < 0) {
                goto send_read_err_pkt;
            }
            if (len < 4) { /* too small? */
                goto recv_again;
            }
        }

        /* Process recv'ed packet */
        opcode = ntohs( ((uint16_t*)rbuf)[0] );
        recv_blk = ntohs( ((uint16_t*)rbuf)[1] );
#if ENABLE_TFTP_DEBUG
        fprintf(stderr, "received %d bytes: %04x %04x\n", len, opcode, recv_blk);
#endif
        if (opcode == TFTP_ERROR) {
            static const char errcode_str[] ALIGN1 =
                "\0"
                "file not found\0"
                "access violation\0"
                "disk full\0"
                "bad operation\0"
                "unknown transfer id\0"
                "file already exists\0"
                "no such user\0"
                "bad option";

            const char *msg = "";

            if (len > 4 && rbuf[4] != '\0') {
                msg = &rbuf[4];
                rbuf[io_bufsize - 1] = '\0'; /* paranoia */
            } else if (recv_blk <= 8) {
                msg = nth_string(errcode_str, recv_blk);
            }
            bb_error_msg("server error: (%u) %s", recv_blk, msg);
            goto ret;
        }

#if ENABLE_FEATURE_TFTP_BLOCKSIZE
        if (expect_OACK) {
            expect_OACK = 0;
            if (opcode == TFTP_OACK) {
                /* server seems to support options */
                char *res;

                res = tftp_get_option("blksize", &rbuf[2], len - 2);
                if (res) {
                    blksize = tftp_blksize_check(res, blksize);
                    if (blksize < 0) {
                        G_error_pkt_reason = ERR_BAD_OPT;
                        goto send_err_pkt;
                    }
                    io_bufsize = blksize + 4;
                }
# if ENABLE_FEATURE_TFTP_PROGRESS_BAR
                if (remote_file && G.size == 0) { /* if we don't know it yet */
                    res = tftp_get_option("tsize", &rbuf[2], len - 2);
                    if (res) {
                        G.size = bb_strtoull(res, NULL, 10);
                        if (G.size)
                            tftp_progress_init();
                    }
                }
# endif
                if (CMD_GET(option_mask32)) {
                    /* We'll send ACK for OACK,
                     * such ACK has "block no" of 0 */
                    block_nr = 0;
                }
                continue;
            }
            /* rfc2347:
             * "An option not acknowledged by the server
             * must be ignored by the client and server
             * as if it were never requested." */
            if (blksize != TFTP_BLKSIZE_DEFAULT)
                bb_error_msg("falling back to blocksize "TFTP_BLKSIZE_DEFAULT_STR);
            blksize = TFTP_BLKSIZE_DEFAULT;
            io_bufsize = TFTP_BLKSIZE_DEFAULT + 4;
        }
#endif
        /* block_nr is already advanced to next block# we expect
         * to get / block# we are about to send next time */

        if (CMD_GET(option_mask32) && (opcode == TFTP_DATA)) {
            if (recv_blk == block_nr) {
                int sz = full_write(local_fd, &rbuf[4], len - 4);
                if (sz != len - 4) {
                    strcpy(G_error_pkt_str, bb_msg_write_error);
                    G_error_pkt_reason = ERR_WRITE;
                    goto send_err_pkt;
                }
                if (sz != blksize) {
                    finished = 1;
                }
                IF_FEATURE_TFTP_PROGRESS_BAR(G.pos += sz;)
                continue; /* send ACK */
            }
/* Disabled to cope with servers with Sorcerer's Apprentice Syndrome */
#if 0
            if (recv_blk == (block_nr - 1)) {
                /* Server lost our TFTP_ACK.  Resend it */
                block_nr = recv_blk;
                continue;
            }
#endif
        }

        if (CMD_PUT(option_mask32) && (opcode == TFTP_ACK)) {
            /* did peer ACK our last DATA pkt? */
            if (recv_blk == (uint16_t) (block_nr - 1)) {
                if (finished)
                    goto ret;
                continue; /* send next block */
            }
        }
        /* Awww... recv'd packet is not recognized! */
        goto recv_again;
        /* why recv_again? - rfc1123 says:
         * "The sender (i.e., the side originating the DATA packets)
         *  must never resend the current DATA packet on receipt
         *  of a duplicate ACK".
         * DATA pkts are resent ONLY on timeout.
         * Thus "goto send_again" will ba a bad mistake above.
         * See:
         * http://en.wikipedia.org/wiki/Sorcerer's_Apprentice_Syndrome
         */
    } /* end of "while (1)" */
 ret:
    if (ENABLE_FEATURE_CLEAN_UP) {
        close(local_fd);
        close(socket_fd);
        free(xbuf);
        free(rbuf);
    }
    return finished == 0; /* returns 1 on failure */

 send_read_err_pkt:
    strcpy(G_error_pkt_str, bb_msg_read_error);
 send_err_pkt:
    if (G_error_pkt_str[0])
        bb_error_msg("%s", G_error_pkt_str);
    G.error_pkt[1] = TFTP_ERROR;
    xsendto(socket_fd, G.error_pkt, 4 + 1 + strlen(G_error_pkt_str),
            &peer_lsa->u.sa, peer_lsa->len);
    return EXIT_FAILURE;
#undef remote_file
}

#if ENABLE_TFTP

int tftp_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int tftp_main(int argc UNUSED_PARAM, char **argv)
{
    len_and_sockaddr *peer_lsa;
    const char *local_file = NULL;
    const char *remote_file = NULL;
# if ENABLE_FEATURE_TFTP_BLOCKSIZE
    const char *blksize_str = TFTP_BLKSIZE_DEFAULT_STR;
    int blksize;
# endif
    int result;
    int port;
    IF_GETPUT(int opt;)

    INIT_G();

    /* -p or -g is mandatory, and they are mutually exclusive */
    opt_complementary = "" IF_FEATURE_TFTP_GET("g:") IF_FEATURE_TFTP_PUT("p:")
            IF_GETPUT("g--p:p--g:");

    IF_GETPUT(opt =) getopt32(argv,
            IF_FEATURE_TFTP_GET("g") IF_FEATURE_TFTP_PUT("p")
                "l:r:" IF_FEATURE_TFTP_BLOCKSIZE("b:"),
            &local_file, &remote_file
            IF_FEATURE_TFTP_BLOCKSIZE(, &blksize_str));
    argv += optind;

# if ENABLE_FEATURE_TFTP_BLOCKSIZE
    /* Check if the blksize is valid:
     * RFC2348 says between 8 and 65464 */
    blksize = tftp_blksize_check(blksize_str, 65564);
    if (blksize < 0) {
        //bb_error_msg("bad block size");
        return EXIT_FAILURE;
    }
# endif

    if (remote_file) {
        if (!local_file) {
            const char *slash = strrchr(remote_file, '/');
            local_file = slash ? slash + 1 : remote_file;
        }
    } else {
        remote_file = local_file;
    }

    /* Error if filename or host is not known */
    if (!remote_file || !argv[0])
        bb_show_usage();

    port = bb_lookup_port(argv[1], "udp", 69);
    peer_lsa = xhost2sockaddr(argv[0], port);

# if ENABLE_TFTP_DEBUG
    fprintf(stderr, "using server '%s', remote_file '%s', local_file '%s'\n",
            xmalloc_sockaddr2dotted(&peer_lsa->u.sa),
            remote_file, local_file);
# endif

# if ENABLE_FEATURE_TFTP_PROGRESS_BAR
    G.file = remote_file;
# endif
    result = tftp_protocol(
        NULL /*our_lsa*/, peer_lsa,
        local_file, remote_file
        IF_FEATURE_TFTP_BLOCKSIZE(, 1 /* want_transfer_size */)
        IF_FEATURE_TFTP_BLOCKSIZE(, blksize)
    );
    tftp_progress_done();

    if (result != EXIT_SUCCESS && NOT_LONE_DASH(local_file) && CMD_GET(opt)) {
        unlink(local_file);
    }
    return result;
}

#endif /* ENABLE_TFTP */

#if ENABLE_TFTPD
int tftpd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int tftpd_main(int argc UNUSED_PARAM, char **argv)
{
    len_and_sockaddr *our_lsa;
    len_and_sockaddr *peer_lsa;
    char *mode, *user_opt;
    char *local_file = local_file;
    const char *error_msg;
    int opt, result, opcode;
    IF_FEATURE_TFTP_BLOCKSIZE(int blksize = TFTP_BLKSIZE_DEFAULT;)
    IF_FEATURE_TFTP_BLOCKSIZE(int want_transfer_size = 0;)

    INIT_G();

    our_lsa = get_sock_lsa(STDIN_FILENO);
    if (!our_lsa) {
        /* This is confusing:
         *bb_error_msg_and_die("stdin is not a socket");
         * Better: */
        bb_show_usage();
        /* Help text says that tftpd must be used as inetd service,
         * which is by far the most usual cause of get_sock_lsa
         * failure */
    }
    peer_lsa = xzalloc(LSA_LEN_SIZE + our_lsa->len);
    peer_lsa->len = our_lsa->len;

    /* Shifting to not collide with TFTP_OPTs */
    opt = option_mask32 = TFTPD_OPT | (getopt32(argv, "rcu:l", &user_opt) << 8);
    argv += optind;
    if (opt & TFTPD_OPT_l) {
        openlog(applet_name, LOG_PID, LOG_DAEMON);
        logmode = LOGMODE_SYSLOG;
    }
    if (opt & TFTPD_OPT_u) {
        /* Must be before xchroot */
        G.pw = xgetpwnam(user_opt);
    }
    if (argv[0]) {
        xchroot(argv[0]);
    }

    result = recv_from_to(STDIN_FILENO,
            G.block_buf, sizeof(G.block_buf) + 1,
            /* ^^^ sizeof+1 to reliably detect oversized input */
            0 /* flags */,
            &peer_lsa->u.sa, &our_lsa->u.sa, our_lsa->len);

    error_msg = "malformed packet";
    opcode = ntohs(*(uint16_t*)G.block_buf);
    if (result < 4 || result > sizeof(G.block_buf)
    /*|| G.block_buf[result-1] != '\0' - bug compatibility, see below */
     || (IF_FEATURE_TFTP_PUT(opcode != TFTP_RRQ) /* not download */
         IF_GETPUT(&&)
         IF_FEATURE_TFTP_GET(opcode != TFTP_WRQ) /* not upload */
        )
    ) {
        goto err;
    }
    /* Some HP PA-RISC firmware always sends fixed 516-byte requests,
     * with trailing garbage.
     * Support that by not requiring NUL to be the last byte (see above).
     * To make strXYZ() ops safe, force NUL termination:
     */
    G.block_buf_tail[0] = '\0';

    local_file = G.block_buf + 2;
    if (local_file[0] == '.' || strstr(local_file, "/.")) {
        error_msg = "dot in file name";
        goto err;
    }
    mode = local_file + strlen(local_file) + 1;
    /* RFC 1350 says mode string is case independent */
    if (mode >= G.block_buf + result || strcasecmp(mode, "octet") != 0) {
        goto err;
    }
# if ENABLE_FEATURE_TFTP_BLOCKSIZE
    {
        char *res;
        char *opt_str = mode + sizeof("octet");
        int opt_len = G.block_buf + result - opt_str;
        if (opt_len > 0) {
            res = tftp_get_option("blksize", opt_str, opt_len);
            if (res) {
                blksize = tftp_blksize_check(res, 65564);
                if (blksize < 0) {
                    G_error_pkt_reason = ERR_BAD_OPT;
                    /* will just send error pkt */
                    goto do_proto;
                }
            }
            if (opcode != TFTP_WRQ /* download? */
            /* did client ask us about file size? */
             && tftp_get_option("tsize", opt_str, opt_len)
            ) {
                want_transfer_size = 1;
            }
        }
    }
# endif

    if (!ENABLE_FEATURE_TFTP_PUT || opcode == TFTP_WRQ) {
        if (opt & TFTPD_OPT_r) {
            /* This would mean "disk full" - not true */
            /*G_error_pkt_reason = ERR_WRITE;*/
            error_msg = bb_msg_write_error;
            goto err;
        }
        IF_GETPUT(option_mask32 |= TFTP_OPT_GET;) /* will receive file's data */
    } else {
        IF_GETPUT(option_mask32 |= TFTP_OPT_PUT;) /* will send file's data */
    }

    /* NB: if G_error_pkt_str or G_error_pkt_reason is set up,
     * tftp_protocol() just sends one error pkt and returns */

 do_proto:
    close(STDIN_FILENO); /* close old, possibly wildcard socket */
    /* tftp_protocol() will create new one, bound to particular local IP */
    result = tftp_protocol(
        our_lsa, peer_lsa,
        local_file IF_TFTP(, NULL /*remote_file*/)
        IF_FEATURE_TFTP_BLOCKSIZE(, want_transfer_size)
        IF_FEATURE_TFTP_BLOCKSIZE(, blksize)
    );

    return result;
 err:
    strcpy(G_error_pkt_str, error_msg);
    goto do_proto;
}

#endif /* ENABLE_TFTPD */

#endif /* ENABLE_FEATURE_TFTP_GET || ENABLE_FEATURE_TFTP_PUT */