lib/libstand/tftp.c

/*  $NetBSD: tftp.c,v 1.4 1997/09/17 16:57:07 drochner Exp $     */

/*
 * Copyright (c) 1996
 *  Matthias Drochner.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *  This product includes software developed for the NetBSD Project
 *  by Matthias Drochner.
 * 4. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");

/*
 * Simple TFTP implementation for libsa.
 * Assumes:
 *  - socket descriptor (int) at open_file->f_devdata
 *  - server host IP in global servip
 * Restrictions:
 *  - read only
 *  - lseek only with SEEK_SET or SEEK_CUR
 *  - no big time differences between transfers (<tftp timeout)
 */

#include <sys/types.h>
#include <sys/stat.h>
#include <netinet/in.h>
#include <netinet/udp.h>
#include <netinet/in_systm.h>
#include <arpa/tftp.h>

#include <string.h>

#include "stand.h"
#include "net.h"
#include "netif.h"

#include "tftp.h"

struct tftp_handle;

static int  tftp_open(const char *path, struct open_file *f);
static int  tftp_close(struct open_file *f);
static int  tftp_parse_oack(struct tftp_handle *h, char *buf, size_t len);
static int  tftp_read(struct open_file *f, void *buf, size_t size, size_t *resid);
static int  tftp_write(struct open_file *f, void *buf, size_t size, size_t *resid);
static off_t    tftp_seek(struct open_file *f, off_t offset, int where);
static int  tftp_set_blksize(struct tftp_handle *h, const char *str);
static int  tftp_stat(struct open_file *f, struct stat *sb);
static ssize_t sendrecv_tftp(struct tftp_handle *h,
    ssize_t (*sproc)(struct iodesc *, void *, size_t),
    void *sbuf, size_t ssize,
    ssize_t (*rproc)(struct tftp_handle *h, void *, ssize_t, time_t, unsigned short *),
    void *rbuf, size_t rsize, unsigned short *rtype);

struct fs_ops tftp_fsops = {
    "tftp",
    tftp_open,
    tftp_close,
    tftp_read,
    tftp_write,
    tftp_seek,
    tftp_stat,
    null_readdir
};

extern struct in_addr servip;

static int      tftpport = 2000;
static int  is_open = 0;

/*
 * The legacy TFTP_BLKSIZE value was SEGSIZE(512).
 * TFTP_REQUESTED_BLKSIZE of 1428 is (Ethernet MTU, less the TFTP, UDP and
 * IP header lengths).
 */
#define TFTP_REQUESTED_BLKSIZE 1428

/*
 * Choose a blksize big enough so we can test with Ethernet
 * Jumbo frames in the future.
 */
#define TFTP_MAX_BLKSIZE 9008

struct tftp_handle {
    struct iodesc  *iodesc;
    int             currblock;  /* contents of lastdata */
    int             islastblock;    /* flag */
    int             validsize;
    int             off;
    char           *path;   /* saved for re-requests */
    unsigned int    tftp_blksize;
    unsigned long   tftp_tsize;
    struct {
        u_char header[HEADER_SIZE];
        struct tftphdr t;
        u_char space[TFTP_MAX_BLKSIZE];
    } __packed __aligned(4) lastdata;
};

#define TFTP_MAX_ERRCODE EOPTNEG
static const int tftperrors[TFTP_MAX_ERRCODE + 1] = {
    0,          /* ??? */
    ENOENT,
    EPERM,
    ENOSPC,
    EINVAL,         /* ??? */
    EINVAL,         /* ??? */
    EEXIST,
    EINVAL,         /* ??? */
    EINVAL,         /* Option negotiation failed. */
};

static int  tftp_getnextblock(struct tftp_handle *h);

/* send error message back. */
static void
tftp_senderr(struct tftp_handle *h, u_short errcode, const char *msg)
{
    struct {
        u_char header[HEADER_SIZE];
        struct tftphdr  t;
        u_char space[63]; /* +1 from t */
    } __packed __aligned(4) wbuf;
    char           *wtail;
    int             len;

    len = strlen(msg);
    if (len > sizeof(wbuf.space))
        len = sizeof(wbuf.space);

    wbuf.t.th_opcode = htons((u_short) ERROR);
    wbuf.t.th_code   = htons(errcode);

    wtail = wbuf.t.th_msg;
    bcopy(msg, wtail, len);
    wtail[len] = '\0';
    wtail += len + 1;

    sendudp(h->iodesc, &wbuf.t, wtail - (char *) &wbuf.t);
}

static void
tftp_sendack(struct tftp_handle *h)
{
    struct {
        u_char header[HEADER_SIZE];
        struct tftphdr  t;
    } __packed __aligned(4) wbuf;
    char           *wtail;

    wbuf.t.th_opcode = htons((u_short) ACK);
    wtail = (char *) &wbuf.t.th_block;
    wbuf.t.th_block = htons((u_short) h->currblock);
    wtail += 2;

    sendudp(h->iodesc, &wbuf.t, wtail - (char *) &wbuf.t);
}

static ssize_t
recvtftp(struct tftp_handle *h, void *pkt, ssize_t len, time_t tleft,
    unsigned short *rtype)
{
    struct iodesc *d = h->iodesc;
    struct tftphdr *t;

    errno = 0;

    len = readudp(d, pkt, len, tleft);

    if (len < 4)
        return (-1);

    t = (struct tftphdr *) pkt;
    *rtype = ntohs(t->th_opcode);
    switch (ntohs(t->th_opcode)) {
    case DATA: {
        int got;

        if (htons(t->th_block) != (u_short) d->xid) {
            /*
             * Expected block?
             */
            return (-1);
        }
        if (d->xid == 1) {
            /*
             * First data packet from new port.
             */
            struct udphdr *uh;
            uh = (struct udphdr *) pkt - 1;
            d->destport = uh->uh_sport;
        } /* else check uh_sport has not changed??? */
        got = len - (t->th_data - (char *) t);
        return got;
    }
    case ERROR:
        if ((unsigned) ntohs(t->th_code) > TFTP_MAX_ERRCODE) {
            printf("illegal tftp error %d\n", ntohs(t->th_code));
            errno = EIO;
        } else {
#ifdef TFTP_DEBUG
            printf("tftp-error %d\n", ntohs(t->th_code));
#endif
            errno = tftperrors[ntohs(t->th_code)];
        }
        return (-1);
    case OACK: {
        struct udphdr *uh;
        int tftp_oack_len;

        /*
         * Unexpected OACK. TFTP transfer already in progress.
         * Drop the pkt.
         */
        if (d->xid != 1) {
            return (-1);
        }

        /*
         * Remember which port this OACK came from, because we need
         * to send the ACK or errors back to it.
         */
        uh = (struct udphdr *) pkt - 1;
        d->destport = uh->uh_sport;

        /* Parse options ACK-ed by the server. */
        tftp_oack_len = len - sizeof(t->th_opcode);
        if (tftp_parse_oack(h, t->th_u.tu_stuff, tftp_oack_len) != 0) {
            tftp_senderr(h, EOPTNEG, "Malformed OACK");
            errno = EIO;
            return (-1);
        }
        return (0);
    }
    default:
#ifdef TFTP_DEBUG
        printf("tftp type %d not handled\n", ntohs(t->th_opcode));
#endif
        return (-1);
    }
}

/* send request, expect first block (or error) */
static int
tftp_makereq(struct tftp_handle *h)
{
    struct {
        u_char header[HEADER_SIZE];
        struct tftphdr  t;
        u_char space[FNAME_SIZE + 6];
    } __packed __aligned(4) wbuf;
    char           *wtail;
    int             l;
    ssize_t         res;
    struct tftphdr *t;
    char *tftp_blksize = NULL;
    int blksize_l;
    unsigned short rtype = 0;

    /*
     * Allow overriding default TFTP block size by setting
     * a tftp.blksize environment variable.
     */
    if ((tftp_blksize = getenv("tftp.blksize")) != NULL) {
        tftp_set_blksize(h, tftp_blksize);
    }

    wbuf.t.th_opcode = htons((u_short) RRQ);
    wtail = wbuf.t.th_stuff;
    l = strlen(h->path);
#ifdef TFTP_PREPEND_PATH
    if (l > FNAME_SIZE - (sizeof(TFTP_PREPEND_PATH) - 1))
        return (ENAMETOOLONG);
    bcopy(TFTP_PREPEND_PATH, wtail, sizeof(TFTP_PREPEND_PATH) - 1);
    wtail += sizeof(TFTP_PREPEND_PATH) - 1;
#else
    if (l > FNAME_SIZE)
        return (ENAMETOOLONG);
#endif
    bcopy(h->path, wtail, l + 1);
    wtail += l + 1;
    bcopy("octet", wtail, 6);
    wtail += 6;
    bcopy("blksize", wtail, 8);
    wtail += 8;
    blksize_l = sprintf(wtail, "%d", h->tftp_blksize);
    wtail += blksize_l + 1;
    bcopy("tsize", wtail, 6);
    wtail += 6;
    bcopy("0", wtail, 2);
    wtail += 2;

    t = &h->lastdata.t;

    /* h->iodesc->myport = htons(--tftpport); */
    h->iodesc->myport = htons(tftpport + (getsecs() & 0x3ff));
    h->iodesc->destport = htons(IPPORT_TFTP);
    h->iodesc->xid = 1; /* expected block */

    h->currblock = 0;
    h->islastblock = 0;
    h->validsize = 0;

    res = sendrecv_tftp(h, &sendudp, &wbuf.t, wtail - (char *) &wbuf.t,
               &recvtftp, t, sizeof(*t) + h->tftp_blksize, &rtype);

    if (rtype == OACK)
        return (tftp_getnextblock(h));

    /* Server ignored our blksize request, revert to TFTP default. */
    h->tftp_blksize = SEGSIZE;

    switch (rtype) {
        case DATA: {
            h->currblock = 1;
            h->validsize = res;
            h->islastblock = 0;
            if (res < h->tftp_blksize) {
                h->islastblock = 1; /* very short file */
                tftp_sendack(h);
            }
            return (0);
        }
        case ERROR:
        default:
            return (errno);
    }

}

/* ack block, expect next */
static int
tftp_getnextblock(struct tftp_handle *h)
{
    struct {
        u_char header[HEADER_SIZE];
        struct tftphdr t;
    } __packed __aligned(4) wbuf;
    char           *wtail;
    int             res;
    struct tftphdr *t;
    unsigned short rtype = 0;
    wbuf.t.th_opcode = htons((u_short) ACK);
    wtail = (char *) &wbuf.t.th_block;
    wbuf.t.th_block = htons((u_short) h->currblock);
    wtail += 2;

    t = &h->lastdata.t;

    h->iodesc->xid = h->currblock + 1;  /* expected block */

    res = sendrecv_tftp(h, &sendudp, &wbuf.t, wtail - (char *) &wbuf.t,
               &recvtftp, t, sizeof(*t) + h->tftp_blksize, &rtype);

    if (res == -1)      /* 0 is OK! */
        return (errno);

    h->currblock++;
    h->validsize = res;
    if (res < h->tftp_blksize)
        h->islastblock = 1; /* EOF */

    if (h->islastblock == 1) {
        /* Send an ACK for the last block */
        wbuf.t.th_block = htons((u_short) h->currblock);
        sendudp(h->iodesc, &wbuf.t, wtail - (char *)&wbuf.t);
    }

    return (0);
}

static int
tftp_open(const char *path, struct open_file *f)
{
    struct tftp_handle *tftpfile;
    struct iodesc  *io;
    int             res;
    size_t          pathsize;
    const char     *extraslash;

    if (strcmp(f->f_dev->dv_name, "net") != 0) {
#ifdef __i386__
        if (strcmp(f->f_dev->dv_name, "pxe") != 0)
            return (EINVAL);
#else
        return (EINVAL);
#endif
    }

    if (is_open)
        return (EBUSY);

    tftpfile = (struct tftp_handle *) malloc(sizeof(*tftpfile));
    if (!tftpfile)
        return (ENOMEM);

    memset(tftpfile, 0, sizeof(*tftpfile));
    tftpfile->tftp_blksize = TFTP_REQUESTED_BLKSIZE;
    tftpfile->iodesc = io = socktodesc(*(int *) (f->f_devdata));
    if (io == NULL)
        return (EINVAL);

    io->destip = servip;
    tftpfile->off = 0;
    pathsize = (strlen(rootpath) + 1 + strlen(path) + 1) * sizeof(char);
    tftpfile->path = malloc(pathsize);
    if (tftpfile->path == NULL) {
        free(tftpfile);
        return(ENOMEM);
    }
    if (rootpath[strlen(rootpath) - 1] == '/' || path[0] == '/')
        extraslash = "";
    else
        extraslash = "/";
    res = snprintf(tftpfile->path, pathsize, "%s%s%s",
        rootpath, extraslash, path);
    if (res < 0 || res > pathsize) {
        free(tftpfile->path);
        free(tftpfile);
        return(ENOMEM);
    }

    res = tftp_makereq(tftpfile);

    if (res) {
        free(tftpfile->path);
        free(tftpfile);
        return (res);
    }
    f->f_fsdata = (void *) tftpfile;
    is_open = 1;
    return (0);
}

static int
tftp_read(struct open_file *f, void *addr, size_t size,
    size_t *resid /* out */)
{
    struct tftp_handle *tftpfile;
    tftpfile = (struct tftp_handle *) f->f_fsdata;

    while (size > 0) {
        int needblock, count;

        twiddle(32);

        needblock = tftpfile->off / tftpfile->tftp_blksize + 1;

        if (tftpfile->currblock > needblock) {  /* seek backwards */
            tftp_senderr(tftpfile, 0, "No error: read aborted");
            tftp_makereq(tftpfile); /* no error check, it worked
                         * for open */
        }

        while (tftpfile->currblock < needblock) {
            int res;

            res = tftp_getnextblock(tftpfile);
            if (res) {  /* no answer */
#ifdef TFTP_DEBUG
                printf("tftp: read error\n");
#endif
                return (res);
            }
            if (tftpfile->islastblock)
                break;
        }

        if (tftpfile->currblock == needblock) {
            int offinblock, inbuffer;

            offinblock = tftpfile->off % tftpfile->tftp_blksize;

            inbuffer = tftpfile->validsize - offinblock;
            if (inbuffer < 0) {
#ifdef TFTP_DEBUG
                printf("tftp: invalid offset %d\n",
                    tftpfile->off);
#endif
                return (EINVAL);
            }
            count = (size < inbuffer ? size : inbuffer);
            bcopy(tftpfile->lastdata.t.th_data + offinblock,
                addr, count);

            addr = (char *)addr + count;
            tftpfile->off += count;
            size -= count;

            if ((tftpfile->islastblock) && (count == inbuffer))
                break;  /* EOF */
        } else {
#ifdef TFTP_DEBUG
            printf("tftp: block %d not found\n", needblock);
#endif
            return (EINVAL);
        }

    }

    if (resid)
        *resid = size;
    return (0);
}

static int
tftp_close(struct open_file *f)
{
    struct tftp_handle *tftpfile;
    tftpfile = (struct tftp_handle *) f->f_fsdata;

    /* let it time out ... */

    if (tftpfile) {
        free(tftpfile->path);
        free(tftpfile);
    }
    is_open = 0;
    return (0);
}

static int
tftp_write(struct open_file *f __unused, void *start __unused, size_t size __unused,
    size_t *resid __unused /* out */)
{
    return (EROFS);
}

static int
tftp_stat(struct open_file *f, struct stat *sb)
{
    struct tftp_handle *tftpfile;
    tftpfile = (struct tftp_handle *) f->f_fsdata;

    sb->st_mode = 0444 | S_IFREG;
    sb->st_nlink = 1;
    sb->st_uid = 0;
    sb->st_gid = 0;
    sb->st_size = (off_t) tftpfile->tftp_tsize;
    return (0);
}

static off_t
tftp_seek(struct open_file *f, off_t offset, int where)
{
    struct tftp_handle *tftpfile;
    tftpfile = (struct tftp_handle *) f->f_fsdata;

    switch (where) {
    case SEEK_SET:
        tftpfile->off = offset;
        break;
    case SEEK_CUR:
        tftpfile->off += offset;
        break;
    default:
        errno = EOFFSET;
        return (-1);
    }
    return (tftpfile->off);
}

static ssize_t
sendrecv_tftp(struct tftp_handle *h,
    ssize_t (*sproc)(struct iodesc *, void *, size_t),
    void *sbuf, size_t ssize,
    ssize_t (*rproc)(struct tftp_handle *, void *, ssize_t, time_t, unsigned short *),
    void *rbuf, size_t rsize, unsigned short *rtype)
{
    struct iodesc *d = h->iodesc;
    ssize_t cc;
    time_t t, t1, tleft;

#ifdef TFTP_DEBUG
    if (debug)
        printf("sendrecv: called\n");
#endif

    tleft = MINTMO;
    t = t1 = getsecs();
    for (;;) {
        if ((getsecs() - t) > MAXTMO) {
            errno = ETIMEDOUT;
            return -1;
        }

        cc = (*sproc)(d, sbuf, ssize);
        if (cc != -1 && cc < ssize)
            panic("sendrecv: short write! (%zd < %zu)",
                cc, ssize);

        if (cc == -1) {
            /* Error on transmit; wait before retrying */
            while ((getsecs() - t1) < tleft);
            continue;
        }

recvnext:
        /* Try to get a packet and process it. */
        cc = (*rproc)(h, rbuf, rsize, tleft, rtype);
        /* Return on data, EOF or real error. */
        if (cc != -1 || errno != 0)
            return (cc);
        if ((getsecs() - t1) < tleft) {
            goto recvnext;
        }

        /* Timed out or didn't get the packet we're waiting for */
        tleft += MINTMO;
        if (tleft > (2 * MINTMO)) {
            tleft = (2 * MINTMO);
        }
        t1 = getsecs();
    }
}

static int
tftp_set_blksize(struct tftp_handle *h, const char *str)
{
        char *endptr;
    int new_blksize;
    int ret = 0;

    if (h == NULL || str == NULL)
        return (ret);

    new_blksize =
        (unsigned int)strtol(str, &endptr, 0);

    /*
     * Only accept blksize value if it is numeric.
     * RFC2348 specifies that acceptable values are 8-65464.
     * Let's choose a limit less than MAXRSPACE.
     */
    if (*endptr == '\0' && new_blksize >= 8
        && new_blksize <= TFTP_MAX_BLKSIZE) {
        h->tftp_blksize = new_blksize;
        ret = 1;
    }

    return (ret);
}

/*
 * In RFC2347, the TFTP Option Acknowledgement package (OACK)
 * is used to acknowledge a client's option negotiation request.
 * The format of an OACK packet is:
 *    +-------+---~~---+---+---~~---+---+---~~---+---+---~~---+---+
 *    |  opc  |  opt1  | 0 | value1 | 0 |  optN  | 0 | valueN | 0 |
 *    +-------+---~~---+---+---~~---+---+---~~---+---+---~~---+---+
 *
 *    opc
 *       The opcode field contains a 6, for Option Acknowledgment.
 *
 *    opt1
 *       The first option acknowledgment, copied from the original
 *       request.
 *
 *    value1
 *       The acknowledged value associated with the first option.  If
 *       and how this value may differ from the original request is
 *       detailed in the specification for the option.
 *
 *    optN, valueN
 *       The final option/value acknowledgment pair.
 */
static int
tftp_parse_oack(struct tftp_handle *h, char *buf, size_t len)
{
    /*
     *  We parse the OACK strings into an array
     *  of name-value pairs.
     */
    char *tftp_options[128] = { 0 };
    char *val = buf;
    int i = 0;
    int option_idx = 0;
    int blksize_is_set = 0;
    int tsize = 0;

    unsigned int orig_blksize;

    while (option_idx < 128 && i < len) {
        if (buf[i] == '\0') {
            if (&buf[i] > val) {
                tftp_options[option_idx] = val;
                val = &buf[i] + 1;
                ++option_idx;
            }
        }
        ++i;
    }

    /* Save the block size we requested for sanity check later. */
    orig_blksize = h->tftp_blksize;

    /*
     * Parse individual TFTP options.
     *    * "blksize" is specified in RFC2348.
     *    * "tsize" is specified in RFC2349.
     */
    for (i = 0; i < option_idx; i += 2) {
        if (strcasecmp(tftp_options[i], "blksize") == 0) {
        if (i + 1 < option_idx)
            blksize_is_set =
                tftp_set_blksize(h, tftp_options[i + 1]);
        } else if (strcasecmp(tftp_options[i], "tsize") == 0) {
        if (i + 1 < option_idx)
            tsize = strtol(tftp_options[i + 1], (char **)NULL, 10);
        if (tsize != 0)
            h->tftp_tsize = tsize;
        } else {
        /* Do not allow any options we did not expect to be ACKed. */
        printf("unexpected tftp option '%s'\n", tftp_options[i]);
        return (-1);
        }
    }

    if (!blksize_is_set) {
        /*
         * If TFTP blksize was not set, try defaulting
         * to the legacy TFTP blksize of SEGSIZE(512)
         */
        h->tftp_blksize = SEGSIZE;
    } else if (h->tftp_blksize > orig_blksize) {
        /*
         * Server should not be proposing block sizes that
         * exceed what we said we can handle.
         */
        printf("unexpected blksize %u\n", h->tftp_blksize);
        return (-1);
    }

#ifdef TFTP_DEBUG
    printf("tftp_blksize: %u\n", h->tftp_blksize);
    printf("tftp_tsize: %lu\n", h->tftp_tsize);
#endif
    return 0;
}