tftpdriver.c

RTEMS (Real-Time Executive for Multiprocessor Systems) is a free open source real-time operating sys

/*
 * vim: set expandtab tabstop=4 shiftwidth=4 ai :
 * 
 * Trivial File Transfer Protocol (RFC 1350)
 *
 * Transfer file to/from remote host
 *
 * W. Eric Norum
 * Saskatchewan Accelerator Laboratory
 * University of Saskatchewan
 * Saskatoon, Saskatchewan, CANADA
 * [e-mail]
 *
 *  $Id: tftpDriver.c,v 1.21 2002/10/28 13:55:58 joel Exp $
 *
 */

#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <malloc.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <rtems.h>
#include <rtems/libio.h>
#include <rtems/libio_.h>
#include <rtems/seterr.h>
#include <rtems/rtems_bsdnet.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#ifdef RTEMS_TFTP_DRIVER_DEBUG
int rtems_tftp_driver_debug = 1;
#endif

/*
 * Range of UDP ports to try
 */
#define UDP_PORT_BASE        3180

/*
 * Pathname prefix
 */
#define TFTP_PATHNAME_PREFIX "/TFTP/"

/*
 * Root node_access value
 * By using the address of a local static variable
 * we ensure a unique value for this identifier.
 */
#define ROOT_NODE_ACCESS    (&tftp_mutex)

/*
 * Default limits
 */
#define PACKET_FIRST_TIMEOUT_MILLISECONDS  400
#define PACKET_TIMEOUT_MILLISECONDS        6000
#define OPEN_RETRY_LIMIT                   10
#define IO_RETRY_LIMIT                     10

/*
 * TFTP opcodes
 */
#define TFTP_OPCODE_RRQ     1
#define TFTP_OPCODE_WRQ     2
#define TFTP_OPCODE_DATA    3
#define TFTP_OPCODE_ACK     4
#define TFTP_OPCODE_ERROR   5

/*
 * Largest data transfer
 */
#define TFTP_BUFSIZE        512

/*
 * Packets transferred between machines
 */
union tftpPacket {
    /*
     * RRQ/WRQ packet
     */
    struct tftpRWRQ {
        rtems_unsigned16    opcode;
        char                filename_mode[TFTP_BUFSIZE];
    } tftpRWRQ;

    /*
     * DATA packet
     */
    struct tftpDATA {
        rtems_unsigned16    opcode;
        rtems_unsigned16    blocknum;
        rtems_unsigned8     data[TFTP_BUFSIZE];
    } tftpDATA;

    /*
     * ACK packet
     */
    struct tftpACK {
        rtems_unsigned16    opcode;
        rtems_unsigned16    blocknum;
    } tftpACK;

    /*
     * ERROR packet
     */
    struct tftpERROR {
        rtems_unsigned16    opcode;
        rtems_unsigned16    errorCode;
        char                errorMessage[TFTP_BUFSIZE];
    } tftpERROR;
};

/*
 * State of each TFTP stream
 */
struct tftpStream {
    /*
     * Buffer for storing most recently-received packet
     */
    union tftpPacket    pkbuf;

    /*
     * Last block number transferred
     */
    rtems_unsigned16    blocknum;

    /*
     * Data transfer socket
     */
    int                 socket;
    struct sockaddr_in  myAddress;
    struct sockaddr_in  farAddress;

    /*
     * Indices into buffer
     */
    int     nleft;
    int     nused;

    /*
     * Flags
     */
    int     firstReply;
    int     eof;
    int     writing;
};

/*
 * Number of streams open at the same time
 */
static rtems_id tftp_mutex;
static int nStreams;
static struct tftpStream ** volatile tftpStreams;

typedef const char *tftp_node;
extern rtems_filesystem_operations_table  rtems_tftp_ops;
extern rtems_filesystem_file_handlers_r   rtems_tftp_handlers;

/*
 *  Direct copy from the IMFS.  Look at this.
 */

rtems_filesystem_limits_and_options_t rtems_tftp_limits_and_options = {
   5,   /* link_max */
   6,   /* max_canon */
   7,   /* max_input */
   255, /* name_max */
   255, /* path_max */
   2,   /* pipe_buf */
   1,   /* posix_async_io */
   2,   /* posix_chown_restrictions */
   3,   /* posix_no_trunc */
   4,   /* posix_prio_io */
   5,   /* posix_sync_io */
   6    /* posix_vdisable */
};

static int rtems_tftp_mount_me(
  rtems_filesystem_mount_table_entry_t *temp_mt_entry
)
{
  rtems_status_code  sc;

  temp_mt_entry->mt_fs_root.handlers = &rtems_tftp_handlers;
  temp_mt_entry->mt_fs_root.ops      = &rtems_tftp_ops;

  /*
   *   We have no tftp filesystem specific data to maintain.  This
   *   filesystem may only be mounted ONCE.
   *
   *   And we maintain no real filesystem nodes, so there is no real root.
   */

  temp_mt_entry->fs_info                = NULL;
  temp_mt_entry->mt_fs_root.node_access = ROOT_NODE_ACCESS;

  /*
   *  These need to be looked at for full POSIX semantics.
   */

  temp_mt_entry->pathconf_limits_and_options = rtems_tftp_limits_and_options; 


  /*
   *  Now allocate a semaphore for mutual exclusion.
   *
   *  NOTE:  This could be in an fsinfo for this filesystem type.
   */
  
  sc = rtems_semaphore_create (
    rtems_build_name('T', 'F', 'T', 'P'),
    1,
    RTEMS_FIFO |
    RTEMS_BINARY_SEMAPHORE |
    RTEMS_NO_INHERIT_PRIORITY |
    RTEMS_NO_PRIORITY_CEILING |
    RTEMS_LOCAL,
    0,
    &tftp_mutex
  );

  if (sc != RTEMS_SUCCESSFUL)
    rtems_set_errno_and_return_minus_one( ENOMEM ); 

  return 0;
}

/*
 * Initialize the TFTP driver
 */

int rtems_bsdnet_initialize_tftp_filesystem () 
{
    int                                   status;
    rtems_filesystem_mount_table_entry_t *entry;

    status = mkdir( TFTP_PATHNAME_PREFIX, S_IRWXU | S_IRWXG | S_IRWXO );
    if ( status == -1 )
        return status; 

    status = mount( 
            &entry,
            &rtems_tftp_ops,
            RTEMS_FILESYSTEM_READ_WRITE,
            NULL,
            TFTP_PATHNAME_PREFIX
    );

    if ( status )
        perror( "TFTP mount failed" );

    return status;
}

/*
 * Map error message
 */
static int
tftpErrno (struct tftpStream *tp)
{
    unsigned int tftpError;
    static const int errorMap[] = {
        EINVAL,
        ENOENT,
        EPERM,
        ENOSPC,
        EINVAL,
        ENXIO,
        EEXIST,
        ESRCH,
    };

    tftpError = ntohs (tp->pkbuf.tftpERROR.errorCode);
    if (tftpError < (sizeof errorMap / sizeof errorMap[0]))
        return errorMap[tftpError];
    else
        return 1000 + tftpError;
}

/*
 * Send a message to make the other end shut up
 */
static void
sendStifle (struct tftpStream *tp, struct sockaddr_in *to)
{
    int len;
    struct {
        rtems_unsigned16    opcode;
        rtems_unsigned16    errorCode;
        char                errorMessage[12];
    } msg;

    /*
     * Create the error packet (Unknown transfer ID).
     */
    msg.opcode = htons (TFTP_OPCODE_ERROR);
    msg.errorCode = htons (5);
    len = sizeof msg.opcode + sizeof msg.errorCode + 1;
    len += sprintf (msg.errorMessage, "GO AWAY"); 

    /*
     * Send it
     */
    sendto (tp->socket, (char *)&msg, len, 0, (struct sockaddr *)to, sizeof *to);
}

/*
 * Wait for a data packet
 */
static int
getPacket (struct tftpStream *tp, int retryCount)
{
    int len;
    struct timeval tv;

    if (retryCount == 0) {
        tv.tv_sec = PACKET_FIRST_TIMEOUT_MILLISECONDS / 1000;
        tv.tv_usec = (PACKET_FIRST_TIMEOUT_MILLISECONDS % 1000) * 1000;
    }
    else {
        tv.tv_sec = PACKET_TIMEOUT_MILLISECONDS / 1000;
        tv.tv_usec = (PACKET_TIMEOUT_MILLISECONDS % 1000) * 1000;
    }
    setsockopt (tp->socket, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof tv);
    for (;;) {
        union {
            struct sockaddr s;
            struct sockaddr_in i;
        } from;
        int fromlen = sizeof from;
        len = recvfrom (tp->socket, (char *)&tp->pkbuf,
                                                    sizeof tp->pkbuf, 0,
                                                    &from.s, &fromlen);
        if (len < 0)
            break;
        if (from.i.sin_addr.s_addr == tp->farAddress.sin_addr.s_addr) {
            if (tp->firstReply) {
                tp->firstReply = 0;
                tp->farAddress.sin_port = from.i.sin_port;
            }
            if (tp->farAddress.sin_port == from.i.sin_port) 
                break;
        }

        /*
         * Packet is from someone with whom we are
         * not interested.  Tell them to go away.
         */
        sendStifle (tp, &from.i);
    }
    tv.tv_sec = 0;
    tv.tv_usec = 0;
    setsockopt (tp->socket, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof tv);
#ifdef RTEMS_TFTP_DRIVER_DEBUG
    if (rtems_tftp_driver_debug) {
        if (len >= (int) sizeof tp->pkbuf.tftpACK) {
            int opcode = ntohs (tp->pkbuf.tftpDATA.opcode);
            switch (opcode) {
            default:
                printf ("TFTP: OPCODE %d\n", opcode);
                break;

            case TFTP_OPCODE_DATA:
                printf ("TFTP: RECV %d\n", ntohs (tp->pkbuf.tftpDATA.blocknum));
                break;

            case TFTP_OPCODE_ACK:
                printf ("TFTP: GOT ACK %d\n", ntohs (tp->pkbuf.tftpACK.blocknum));
                break;
            }
        }
        else {
            printf ("TFTP: %d-byte packet\n", len);
        }
    }
#endif
    return len;
}

/*
 * Send an acknowledgement
 */
static int
sendAck (struct tftpStream *tp)
{
#ifdef RTEMS_TFTP_DRIVER_DEBUG
    if (rtems_tftp_driver_debug)
        printf ("TFTP: ACK %d\n", tp->blocknum);
#endif

    /*
     * Create the acknowledgement
     */
    tp->pkbuf.tftpACK.opcode = htons (TFTP_OPCODE_ACK);
    tp->pkbuf.tftpACK.blocknum = htons (tp->blocknum);

    /*
     * Send it
     */
    if (sendto (tp->socket, (char *)&tp->pkbuf, sizeof tp->pkbuf.tftpACK, 0,
                                    (struct sockaddr *)&tp->farAddress,
                                    sizeof tp->farAddress) < 0)
        return errno;
    return 0;
}

/*
 * Release a stream and clear the pointer to it
 */
static void
releaseStream (int s)
{
    rtems_semaphore_obtain (tftp_mutex, RTEMS_WAIT, RTEMS_NO_TIMEOUT);
    free (tftpStreams[s]);
    tftpStreams[s] = NULL;
    rtems_semaphore_release (tftp_mutex);
}

static int rtems_tftp_evaluate_for_make(
   const char                         *path,       /* IN     */
   rtems_filesystem_location_info_t   *pathloc,    /* IN/OUT */
   const char                        **name        /* OUT    */
)
{  
  pathloc->node_access = NULL;
  rtems_set_errno_and_return_minus_one( EIO );    
}

/*
 * Convert a path to canonical form
 */
static void
fixPath (char *path)
{
    char *inp, *outp, *base;

    outp = inp = path;
    base = NULL;
    for (;;) {
        if (inp[0] == '.') {
            if (inp[1] == '\0')
                break;
            if (inp[1] == '/') {
                inp += 2;
                continue;
            }
            if (inp[1] == '.') {
                if (inp[2] == '\0') {
                    if ((base != NULL) && (outp > base)) {
                        outp--;
                        while ((outp > base) && (outp[-1] != '/'))
                            outp--;
                    }
                    break;
                }
                if (inp[2] == '/') {
                    inp += 3;
                    if (base == NULL)
                        continue;
                    if (outp > base) {
                        outp--;
                        while ((outp > base) && (outp[-1] != '/'))
                            outp--;
                    }
                    continue;
                }
            }
        }
        if (base == NULL)
            base = inp;
        while (inp[0] != '/') {
            if ((*outp++ = *inp++) == '\0')
                return;
        }
        *outp++ = '/';
        while (inp[0] == '/')
            inp++;
    }
    *outp = '\0';
    return;
}

static int rtems_tftp_eval_path(  
  const char                        *pathname,     /* IN     */
  int                                flags,        /* IN     */
  rtems_filesystem_location_info_t  *pathloc       /* IN/OUT */
)
{
    pathloc->handlers    = &rtems_tftp_handlers;

    /*
     * Hack to provide the illusion of directories inside the TFTP file system.
     * Paths ending in a / are assumed to be directories.
     */
    if (pathname[strlen(pathname)-1] == '/') {
        int isRelative = (pathloc->node_access != ROOT_NODE_ACCESS);
        char *cp;
        
        /*
         * Reject attempts to open() directories
         */
        if (flags & RTEMS_LIBIO_PERMS_RDWR)
            rtems_set_errno_and_return_minus_one( EISDIR );
        if (isRelative) {
            cp = malloc (strlen(pathloc->node_access)+strlen(pathname)+1);
            if (cp == NULL)
                rtems_set_errno_and_return_minus_one( ENOMEM );
            strcpy (cp, pathloc->node_access);
            strcat (cp, pathname);
        }
        else {
            cp = strdup (pathname);
            if (cp == NULL)
                rtems_set_errno_and_return_minus_one( ENOMEM );
        }
        fixPath (cp);
        pathloc->node_access = cp;
        return 0;
    }
    if (pathloc->node_access != ROOT_NODE_ACCESS)
        pathloc->node_access = 0;