ftpd.c

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/* FIXME: 1. Parse command is a hack.  We can do better.
 *        2. Some sort of access control?
 *        3. OSV: hooks support seems to be bad, as it requires storing of
 *           entire input file in memory.  Seem to be better to change it to
 *           something more reasonable, like having
 *           'hook_write(void const *buf, int count)' routine that will be
 *           called multiple times while file is being received.
 *        4. OSV: Remove hack with "/dev/null"?
 *
 *  FTP Server Daemon
 *
 *  Submitted by: Jake Janovetz <[e-mail]>
 *
 *  Changed by:   Sergei Organov <[e-mail]> (OSV)
 *
 *  Changes:
 *
 *    2001-01-31        Sergei Organov <[e-mail]>
 *
 *      * Hacks with current dir and root dir removed in favor of new libio
 *        support for task-local current and root directories.
 *
 *    2001-01-30        Sergei Organov <[e-mail]>
 *
 *      * Bug in `close_data_socket()' introduced by previous change fixed.
 *      * `command_pasv()' changed to set timeout on socket we are listening on
 *        and code fixed to don't close socket twice on error.
 *      * `serr()' changed to clear `errno'.
 *      * `data_socket()' changed to clear `errno' before `bind()'.
 *      * `session()' changed to clear `errno' before processing session.
 *
 *    2001-01-29        Sergei Organov <[e-mail]>
 *
 *      * `close_data_socket()' fixed to close both active and passive sockets
 *      * Initialize info->data_socket to -1 in `daemon()'
 *      * Initialize `fname' to empty string  in `exec_command()'
 *
 *    2001-01-22        Sergei Organov <[e-mail]>
 *
 *      * Timeouts on sockets implemented. 'idle' field added to
 *        configuration. No timeout by default to keep backward compatibility.
 *        Note: SITE IDLE command not implemented yet.
 *      * Basic global access control implemented. 'access' field added to
 *        configuration. No access limitations by default to keep backward
 *        compatibility.
 *
 *    2001-01-17        Sergei Organov <[e-mail]>
 *
 *      * Anchor data socket for active mode (using self IP and port 20.)
 *      * Fixed default data port support (still not tested).
 *      * Don't allow IP address different from originating host in
 *        PORT command to improve security.
 *      * Fixed bug in MDTM command.
 *      * Check for correctness of parsing of argument in command_port().
 *      * Fixed squeeze_path() to don't allow names like 'NAME/smth' where
 *        'NAME' is not a directory.
 *      * Command parsing a little bit improved: command names are now
 *        converted to upper-case to be more compatible with RFC (command
 *        names are not case-sensitive.)
 *      * Reformat comments so that they have RTEMS look-and-feel.
 *
 *    2001-01-16        Sergei Organov <[e-mail]>
 *
 *      * Fixed DELE, SITE CHMOD, RMD, MKD broken by previous changes
 *      * True ASCII mode implemented (doesn't work for hooks and /dev/null)
 *      * Passive mode implemented, PASV command added.
 *      * Default port for data connection could be used (untested, can't find
 *        ftp client that doesn't send PORT command)
 *      * SYST reply changed to UNIX, as former RTEMS isn't registered name.
 *      * Reply codes reviewed and fixed.
 *
 *    2001-01-08        Sergei Organov <[e-mail]>
 *
 *      * use pool of pre-created threads to handle sessions
 *      * LIST output now similar to what "/bin/ls -al" would output, thus
 *        FTP clients could parse it.
 *      * LIST NAME now works (both for files and directories)
 *      * keep track of CWD for every session separately
 *      * ability to specify root directory name in configuration table
 *      * options sent in commands are ignored, thus LIST -al FILE works
 *      * added support for NLST, CDUP and MDTM commands
 *      * buffers are allocated on stack instead of heap where possible
 *      * drop using of task notepad to pass parameters - use function
 *        arguments instead
 *      * various bug-fixes, e.g., use of PF_INET in socket() instead of
 *        AF_INET, use snprintf() instead of sprintf() everywhere for safety,
 *        etc.
 *
 *  $Id: ftpd.c,v 1.9 2002/09/07 23:07:58 joel Exp $
 */

/*************************************************************************
 *                                 ftpd.c
 *************************************************************************
 * Description:
 *
 *    This file contains the daemon which services requests that appear
 *    on the FTP port.  This server is compatible with FTP, but it
 *    also provides 'hooks' to make it usable in situations where files
 *    are not used/necessary.  Once the server is started, it runs
 *    forever.
 *
 *
 *    Organization:
 *
 *       The FTP daemon is started upon boot along with a (configurable)
 *       number of tasks to handle sessions.  It runs all the time and
 *       waits for connections on the known FTP port (21).  When
 *       a connection is made, it wakes-up a 'session' task.  That
 *       session then interacts with the remote host.  When the session
 *       is complete, the session task goes to sleep.  The daemon still
 *       runs, however.
 *
 *
 * Supported commands are:
 *
 * RETR xxx     - Sends a file from the client.
 * STOR xxx     - Receives a file from the client.  xxx = filename.
 * LIST xxx     - Sends a file list to the client.
 * NLST xxx     - Sends a file list to the client.
 * USER         - Does nothing.
 * PASS         - Does nothing.
 * SYST         - Replies with the system type (`RTEMS').
 * DELE xxx     - Delete file xxx.
 * MKD xxx      - Create directory xxx.
 * RMD xxx      - Remove directory xxx.
 * PWD          - Print working directory.
 * CWD xxx      - Change working directory.
 * CDUP         - Change to upper directory.
 * SITE CHMOD xxx yyy - Change permissions on file yyy to xxx.
 * PORT a,b,c,d,x,y   - Setup for a data port to IP address a.b.c.d
 *                      and port (x*256 + y).
 * MDTM xxx     - Send file modification date/time to the client.
 *                xxx = filename.
 * PASV         - Use passive mode data connection.
 *
 *
 * The public routines contained in this file are:
 *
 *    rtems_initialize_ftpd - Initializes and starts the server daemon,
 *                            then returns to its caller.
 *
 *------------------------------------------------------------------------
 * Jake Janovetz
 * University of Illinois
 * 1406 West Green Street
 * Urbana IL  61801
 *************************************************************************
 * Change History:
 *  12/01/97   - Creation (JWJ)
 *  2001-01-08 - Changes by OSV
 *************************************************************************/

/*************************************************************************
 * Meanings of first and second digits of reply codes:
 *
 * Reply:  Description:
 *-------- --------------
 *  1yz    Positive preliminary reply.  The action is being started but
 *         expect another reply before sending another command.
 *  2yz    Positive completion reply.  A new command can be sent.
 *  3yz    Positive intermediate reply.  The command has been accepted
 *         but another command must be sent.
 *  4yz    Transient negative completion reply.  The requested action did
 *         not take place, but the error condition is temporary so the
 *         command can be reissued later.
 *  5yz    Permanent negative completion reply.  The command was not
 *         accepted and should not be retried.
 *-------------------------------------------------------------------------
 *  x0z    Syntax errors.
 *  x1z    Information.
 *  x2z    Connections.  Replies referring to the control or data
 *         connections.
 *  x3z    Authentication and accounting.  Replies for the login or
 *         accounting commands.
 *  x4z    Unspecified.
 *  x5z    Filesystem status.
 *************************************************************************/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <dirent.h>
#include <errno.h>
#include <ctype.h>

#include <rtems.h>
#include <rtems/rtems_bsdnet.h>
#include <rtems/error.h>
#include <rtems/libio.h>
#include <rtems/userenv.h>
#include <syslog.h>

#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/ftp.h>
#include <netinet/in.h>

#include "ftpd.h"


#ifdef __GNUC__
/* change to #if 1 to disable syslog entirely */
#if 0
#undef  syslog
#define syslog(a, b, ...) while(0){}
#endif
#endif

#define FTPD_SERVER_MESSAGE  "RTEMS FTP server (Version 1.1-JWJ) ready."

#define FTPD_SYSTYPE "UNIX Type: L8"

/* Seem to be unused */
#if 0
#define FTPD_WELCOME_MESSAGE \
   "Welcome to the RTEMS FTP server.\n" \
   "\n" \
   "Login accepted.\n"
#endif

/* Various buffer sizes */
enum
{
  FTPD_BUFSIZE  = 256,       /* Size for temporary buffers */
  FTPD_DATASIZE = 1024,      /* Size for file transfer buffers */
  FTPD_STACKSIZE = 8 * 1024, /* Tasks stack size */
};

/* Event to be used by session tasks for waiting */
enum
{
  FTPD_RTEMS_EVENT = RTEMS_EVENT_1
};

/* Configuration table */
extern struct rtems_ftpd_configuration rtems_ftpd_configuration;

/* this is not prototyped in strict ansi mode */
FILE *fdopen (int fildes, const char *mode);

/*PAGE
 * SessionInfo structure.
 *
 * The following structure is allocated for each session.
 */
typedef struct
{
  struct sockaddr_in  ctrl_addr;   /* Control connection self address */
  struct sockaddr_in  data_addr;   /* Data address set by PORT command */
  struct sockaddr_in  def_addr;    /* Default address for data */
  int                 use_default; /* 1 - use default address for data */
  FILE                *ctrl_fp;    /* File pointer for control connection */
  int                 ctrl_socket; /* Socket for ctrl connection */
  int                 pasv_socket; /* Socket for PASV connection */
  int                 data_socket; /* Socket for data connection */
  int                 idle;        /* Timeout in seconds */
  int                 xfer_mode;   /* Transfer mode (ASCII/binary) */
  rtems_id            tid;         /* Task id */
} FTPD_SessionInfo_t;


/*
 * TaskPool structure.
 */
typedef struct
{
  FTPD_SessionInfo_t    *info;
  FTPD_SessionInfo_t    **queue;
  int                   count;
  int                   head;
  int                   tail;
  rtems_id              mutex;
  rtems_id              sem;
} FTPD_TaskPool_t;

/*
 * Task pool instance.
 */
static FTPD_TaskPool_t task_pool;

/*
 * Root directory
 */

static char const* ftpd_root = "/";

/*
 * Default idle timeout for sockets in seconds.
 */
static int ftpd_timeout = 0;

/*
 * Global access flags.
 */
static int ftpd_access = 0;

/*PAGE
 *
 * serr
 *
 * Return error string corresponding to current 'errno'.
 *
 */
static char const*
serr(void)
{
  int err = errno;
  errno = 0;
  return strerror(err);
}

/*PAGE
 *
 * Utility routines for access control.
 *
 */

static int
can_read(void)
{
  return (ftpd_access & FTPD_NO_READ) == 0;
}

static int
can_write(void)
{
  return (ftpd_access & FTPD_NO_WRITE) == 0;
}

/*PAGE
 *
 * Task pool management routines
 *
 */


/*PAGE
 *
 * task_pool_done
 *
 * Cleanup task pool.
 *
 * Input parameters:
 *   count - number of entries in task pool to cleanup
 *
 * Output parameters:
 *   NONE
 *
 */
static void
task_pool_done(int count)
{
  int i;
  for(i = 0; i < count; ++i)
    rtems_task_delete(task_pool.info[i].tid);
  if(task_pool.info)
    free(task_pool.info);
  if(task_pool.queue)
    free(task_pool.queue);
  if(task_pool.mutex != (rtems_id)-1)
    rtems_semaphore_delete(task_pool.mutex);
  if(task_pool.sem != (rtems_id)-1)
    rtems_semaphore_delete(task_pool.sem);
  task_pool.info = 0;
  task_pool.queue = 0;
  task_pool.count = 0;
  task_pool.sem = -1;
  task_pool.mutex = -1;
}

/*PAGE
 *
 * task_pool_init
 *
 * Initialize task pool.
 *
 * Input parameters:
 *   count    - number of entries in task pool to create
 *   priority - priority tasks are started with
 *
 * Output parameters:
 *   returns 1 on success, 0 on failure.
 *
 */
static void session(rtems_task_argument arg); /* Forward declare */

static int
task_pool_init(int count, rtems_task_priority priority)
{
  int i;
  rtems_status_code sc;
  char id = 'a';

  task_pool.count = 0;
  task_pool.head = task_pool.tail = 0;
  task_pool.mutex = (rtems_id)-1;
  task_pool.sem   = (rtems_id)-1;

  sc = rtems_semaphore_create(
    rtems_build_name('F', 'T', 'P', 'M'),
    1,
    RTEMS_DEFAULT_ATTRIBUTES
    | RTEMS_BINARY_SEMAPHORE
    | RTEMS_INHERIT_PRIORITY
    | RTEMS_PRIORITY,
    RTEMS_NO_PRIORITY,
    &task_pool.mutex);

  if(sc == RTEMS_SUCCESSFUL)
    sc = rtems_semaphore_create(
      rtems_build_name('F', 'T', 'P', 'S'),
      count,
      RTEMS_DEFAULT_ATTRIBUTES,
      RTEMS_NO_PRIORITY,
      &task_pool.sem);

  if(sc != RTEMS_SUCCESSFUL) {
    task_pool_done(0);
    syslog(LOG_ERR, "ftpd: Can not create semaphores");
    return 0;
  }

  task_pool.info = (FTPD_SessionInfo_t*)
    malloc(sizeof(FTPD_SessionInfo_t) * count);
  task_pool.queue = (FTPD_SessionInfo_t**)
    malloc(sizeof(FTPD_SessionInfo_t*) * count);
  if (NULL == task_pool.info || NULL == task_pool.queue)
  {
    task_pool_done(0);
    syslog(LOG_ERR, "ftpd: Not enough memory");
    return 0;
  }

  for(i = 0; i < count; ++i)
  {
    FTPD_SessionInfo_t *info = &task_pool.info[i];
    sc = rtems_task_create(rtems_build_name('F', 'T', 'P', id),
      priority, FTPD_STACKSIZE,
      RTEMS_PREEMPT | RTEMS_NO_TIMESLICE |
      RTEMS_NO_ASR | RTEMS_INTERRUPT_LEVEL(0),
      RTEMS_NO_FLOATING_POINT | RTEMS_LOCAL,
      &info->tid);
    if (sc == RTEMS_SUCCESSFUL)
    {
      sc = rtems_task_start(
        info->tid, session, (rtems_task_argument)info);
      if (sc != RTEMS_SUCCESSFUL)
        task_pool_done(i);
    }
    else
      task_pool_done(i + 1);
    if (sc != RTEMS_SUCCESSFUL)
    {
      syslog(LOG_ERR, "ftpd: Could not create/start FTPD session: %s",
        rtems_status_text(sc));
      return 0;
    }
    task_pool.queue[i] = task_pool.info + i;
    if (++id > 'z')
      id = 'a';
  }
  task_pool.count = count;
  return 1;
}

/*PAGE
 *
 * task_pool_obtain
 *
 * Obtain free task from task pool.
 *
 * Input parameters:
 *   NONE
 *
 * Output parameters:
 *   returns pointer to the corresponding SessionInfo structure on success,
 *           NULL if there are no free tasks in the pool.
 *
 */
static FTPD_SessionInfo_t*
task_pool_obtain()
{
  FTPD_SessionInfo_t* info = 0;
  rtems_status_code sc;
  sc = rtems_semaphore_obtain(task_pool.sem, RTEMS_NO_WAIT, RTEMS_NO_TIMEOUT);
  if (sc == RTEMS_SUCCESSFUL)
  {
    rtems_semaphore_obtain(task_pool.mutex, RTEMS_WAIT, RTEMS_NO_TIMEOUT);
    info = task_pool.queue[task_pool.head];
    if(++task_pool.head >= task_pool.count)
      task_pool.head = 0;
    rtems_semaphore_release(task_pool.mutex);
  }
  return info;
}

/*PAGE
 *
 * task_pool_release
 *
 * Return task obtained by 'obtain()' back to the task pool.
 *
 * Input parameters:
 *   info  - pointer to corresponding SessionInfo structure.
 *
 * Output parameters:
 *   NONE
 *
 */
static void
task_pool_release(FTPD_SessionInfo_t* info)
{
  rtems_semaphore_obtain(task_pool.mutex, RTEMS_WAIT, RTEMS_NO_TIMEOUT);