ftpd.c

来自「RTEMS (Real-Time Executive for Multiproc」· C语言 代码 · 共 2,063 行 · 第 1/4 页

 *
 * Input parameters:
 *   p  - pointer to pointer to command
 *
 * Output parameters:
 *   p  - is changed to point to first non-option argument
 */
static void
skip_options(char **p)
{
  char* buf = *p;
  char* last = NULL;
  while(1) {
    while(isspace(*buf))
      ++buf;
    if(*buf == '-') {
      if(*++buf == '-') { /* `--' should terminate options */
        if(isspace(*++buf)) {
          last = buf;
          do ++buf;
          while(isspace(*buf));
          break;
        }
      }
      while(*buf && !isspace(*buf))
        ++buf;
      last = buf;
    }
    else
      break;
  }
  if(last)
    *last = '\0';
  *p = buf;
}

/*PAGE
 *
 * split_command
 *
 * Split command into command itself, options, and arguments. Command itself
 * is converted to upper case.
 *
 * Input parameters:
 *   buf - initial command string
 *
 * Output parameter:
 *   buf  - is modified by inserting '\0' at ends of split entities
 *   cmd  - upper-cased command code
 *   opts - string containing all the options
 *   args - string containing all the arguments
 */
void
split_command(char *buf, char **cmd, char **opts, char **args)
{
  char* eoc;
  char* p = buf;
  while(isspace(*p))
    ++p;
  *cmd = p;
  while(*p && !isspace(*p))
  {
    *p = toupper(*p);
    ++p;
  }
  eoc = p;
  if(*p)
    *p++ = '\0';
  while(isspace(*p))
    ++p;
  *opts = p;
  skip_options(&p);
  *args = p;
  if(*opts == p)
    *opts = eoc;
  while(*p && *p != '\r' && *p != '\n')
    ++p;
  if(*p)
    *p++ = '\0';
}

/*PAGE
 *
 * exec_command
 *
 * Parse and execute FTP command.
 *
 * FIXME: This section is somewhat of a hack.  We should have a better
 *        way to parse commands.
 *
 * Input parameters:
 *   info - corresponding SessionInfo structure
 *   cmd  - command to be executed (upper-case)
 *   args - arguments of the command
 *
 * Output parameters:
 *    NONE
 */
static void
exec_command(FTPD_SessionInfo_t *info, char* cmd, char* args)
{
  char fname[FTPD_BUFSIZE];
  int wrong_command = 0;

  fname[0] = '\0';

  if (!strcmp("PORT", cmd))
  {
    command_port(info, args);
  }
  else if (!strcmp("PASV", cmd))
  {
    command_pasv(info);
  }
  else if (!strcmp("RETR", cmd))
  {
    sscanf(args, "%254s", fname);
    command_retrieve(info, fname);
  }
  else if (!strcmp("STOR", cmd))
  {
    sscanf(args, "%254s", fname);
    command_store(info, fname);
  }
  else if (!strcmp("LIST", cmd))
  {
    sscanf(args, "%254s", fname);
    command_list(info, fname, 1);
  }
  else if (!strcmp("NLST", cmd))
  {
    sscanf(args, "%254s", fname);
    command_list(info, fname, 0);
  }
  else if (!strcmp("MDTM", cmd))
  {
    sscanf(args, "%254s", fname);
    command_mdtm(info, fname);
  }
  else if (!strcmp("SYST", cmd))
  {
    send_reply(info, 215, FTPD_SYSTYPE);
  }
  else if (!strcmp("TYPE", cmd))
  {
    if (args[0] == 'I')
    {
      info->xfer_mode = TYPE_I;
      send_reply(info, 200, "Type set to I.");
    }
    else if (args[0] == 'A')
    {
      info->xfer_mode = TYPE_A;
      send_reply(info, 200, "Type set to A.");
    }
    else
    {
      info->xfer_mode = TYPE_I;
      send_reply(info, 504, "Type not implemented.  Set to I.");
    }
  }
  else if (!strcmp("USER", cmd) || !strcmp("PASS", cmd))
  {
    send_reply(info, 230, "User logged in.");
  }
  else if (!strcmp("DELE", cmd))
  {
    if(!can_write())
    {
      send_reply(info, 550, "Access denied.");
    }
    else if (
      1 == sscanf(args, "%254s", fname) &&
      unlink(fname) == 0)
    {
      send_reply(info, 257, "DELE successful.");
    }
    else
    {
      send_reply(info, 550, "DELE failed.");
    }
  }
  else if (!strcmp("SITE", cmd))
  {
    char* opts;
    split_command(args, &cmd, &opts, &args);
    if(!strcmp("CHMOD", cmd))
    {
      int mask;

      if(!can_write())
      {
        send_reply(info, 550, "Access denied.");
      }
      else if(
        2 == sscanf(args, "%o %254s", &mask, fname) &&
        chmod(fname, (mode_t)mask) == 0)
      {
        send_reply(info, 257, "CHMOD successful.");
      }
      else
      {
        send_reply(info, 550, "CHMOD failed.");
      }
    }
    else
      wrong_command = 1;
  }
  else if (!strcmp("RMD", cmd))
  {
    if(!can_write())
    {
      send_reply(info, 550, "Access denied.");
    }
    else if (
      1 == sscanf(args, "%254s", fname) &&
      rmdir(fname) == 0)
    {
      send_reply(info, 257, "RMD successful.");
    }
    else
    {
      send_reply(info, 550, "RMD failed.");
    }
  }
  else if (!strcmp("MKD", cmd))
  {
    if(!can_write())
    {
      send_reply(info, 550, "Access denied.");
    }
    else if (
      1 == sscanf(args, "%254s", fname) &&
      mkdir(fname, S_IRWXU | S_IRWXG | S_IRWXO) == 0)
    {
      send_reply(info, 257, "MKD successful.");
    }
    else
    {
      send_reply(info, 550, "MKD failed.");
    }
  }
  else if (!strcmp("CWD", cmd))
  {
    sscanf(args, "%254s", fname);
    command_cwd(info, fname);
  }
  else if (!strcmp("CDUP", cmd))
  {
    command_cwd(info, "..");
  }
  else if (!strcmp("PWD", cmd))
  {
    command_pwd(info);
  }
  else
    wrong_command = 1;

  if(wrong_command)
    send_reply(info, 500, "Command not understood.");
}


/*PAGE
 *
 * session
 *
 * This task handles single session.  It is waked up when the FTP daemon gets a
 * service request from a remote machine.  Here, we watch for commands that
 * will come through the control connection.  These commands are then parsed
 * and executed until the connection is closed, either unintentionally or
 * intentionally with the "QUIT" command.
 *
 * Input parameters:
 *   arg - pointer to corresponding SessionInfo.
 *
 * Output parameters:
 *   NONE
 */
static void
session(rtems_task_argument arg)
{
  FTPD_SessionInfo_t  *const info = (FTPD_SessionInfo_t  *)arg;
  int chroot_made = 0;

  rtems_libio_set_private_env();

  /* chroot() can fail here because the directory may not exist yet. */
  chroot_made = chroot(ftpd_root) == 0;

  while(1)
  {
    rtems_event_set set;

    rtems_event_receive(FTPD_RTEMS_EVENT, RTEMS_EVENT_ANY, RTEMS_NO_TIMEOUT,
      &set);

    chroot_made = chroot_made || chroot(ftpd_root) == 0;
    chdir("/");

    errno = 0;

    send_reply(info, 220, FTPD_SERVER_MESSAGE);

    while (1)
    {
      char buf[FTPD_BUFSIZE];
      char *cmd, *opts, *args;

      if (fgets(buf, FTPD_BUFSIZE, info->ctrl_fp) == NULL)
      {
        syslog(LOG_INFO, "ftpd: Connection aborted.");
        break;
      }

      split_command(buf, &cmd, &opts, &args);

      if (!strcmp("QUIT", cmd))
      {
        send_reply(info, 221, "Goodbye.");
        break;
      }
      else
      {
        exec_command(info, cmd, args);
      }
    }

    /* Close connection and put ourselves back into the task pool. */
    close_data_socket(info);
    close_stream(info);
    task_pool_release(info);
  }
}


/*PAGE
 *
 * daemon
 *
 * This task runs forever.  It waits for service requests on the FTP port
 * (port 21 by default).  When a request is received, it opens a new session
 * to handle those requests until the connection is closed.
 *
 * Input parameters:
 *   NONE
 *
 * Output parameters:
 *   NONE
 */
static void
daemon()
{
  int                 s;
  int                 addrLen;
  struct sockaddr_in  addr;
  FTPD_SessionInfo_t  *info = NULL;


  s = socket(PF_INET, SOCK_STREAM, 0);
  if (s < 0)
    syslog(LOG_ERR, "ftpd: Error creating socket: %s", serr());

  addr.sin_family      = AF_INET;
  addr.sin_port        = htons(rtems_ftpd_configuration.port);
  addr.sin_addr.s_addr = htonl(INADDR_ANY);
  memset(addr.sin_zero, 0, sizeof(addr.sin_zero));

  if (0 > bind(s, (struct sockaddr *)&addr, sizeof(addr)))
    syslog(LOG_ERR, "ftpd: Error binding control socket: %s", serr());
  else if (0 > listen(s, 1))
    syslog(LOG_ERR, "ftpd: Error listening on control socket: %s", serr());
  else while (1)
  {
    int ss;
    addrLen = sizeof(addr);
    ss = accept(s, (struct sockaddr *)&addr, &addrLen);
    if (0 > ss)
      syslog(LOG_ERR, "ftpd: Error accepting control connection: %s", serr());
    else if(!set_socket_timeout(ss, ftpd_timeout))
      close_socket(ss);
    else
    {
      info = task_pool_obtain();
      if (NULL == info)
      {
        close_socket(ss);
      }
      else
      {
        info->ctrl_socket = ss;
        if ((info->ctrl_fp = fdopen(info->ctrl_socket, "r+")) == NULL)
        {
          syslog(LOG_ERR, "ftpd: fdopen() on socket failed: %s", serr());
          close_stream(info);
          task_pool_release(info);
        }
        else
        {
          /* Initialize corresponding SessionInfo structure */
          info->def_addr = addr;
          if(0 > getsockname(ss, (struct sockaddr *)&addr, &addrLen))
          {
            syslog(LOG_ERR, "ftpd: getsockname(): %s", serr());
            close_stream(info);
            task_pool_release(info);
          }
          else
          {
            info->use_default = 1;
            info->ctrl_addr  = addr;
            info->pasv_socket = -1;
            info->data_socket = -1;
            info->xfer_mode   = TYPE_A;
            info->data_addr.sin_port =
              htons(ntohs(info->ctrl_addr.sin_port) - 1);
            info->idle = ftpd_timeout;
            /* Wakeup the session task.  The task will call task_pool_release
               after it closes connection. */
            rtems_event_send(info->tid, FTPD_RTEMS_EVENT);
          }
        }
      }
    }
  }
  rtems_task_delete(RTEMS_SELF);
}


/*PAGE
 *
 * rtems_ftpd_start
 *
 * Here, we start the FTPD task which waits for FTP requests and services
 * them.  This procedure returns to its caller once the task is started.
 *
 *
 * Input parameters:
 *
 * Output parameters:
 *    returns RTEMS_SUCCESSFUL on successful start of the daemon.
 */
int
rtems_initialize_ftpd()
{
  rtems_status_code   sc;
  rtems_id            tid;
  rtems_task_priority priority;
  int count;

  if (rtems_ftpd_configuration.port == 0)
  {
    rtems_ftpd_configuration.port = FTPD_CONTROL_PORT;
  }

  if (rtems_ftpd_configuration.priority == 0)
  {
    rtems_ftpd_configuration.priority = 40;
  }
  priority = rtems_ftpd_configuration.priority;

  ftpd_timeout = rtems_ftpd_configuration.idle;
  if (ftpd_timeout < 0)
    ftpd_timeout = 0;
  rtems_ftpd_configuration.idle = ftpd_timeout;

  ftpd_access = rtems_ftpd_configuration.access;

  if (rtems_ftpd_configuration.tasks_count <= 0)
    rtems_ftpd_configuration.tasks_count = 1;
  count = rtems_ftpd_configuration.tasks_count;

  if (!task_pool_init(count, priority))
  {
    syslog(LOG_ERR, "ftpd: Could not initialize task pool.");
    return RTEMS_UNSATISFIED;
  }

  sc = rtems_task_create(rtems_build_name('F', 'T', 'P', 'D'),
    priority, FTPD_STACKSIZE,
    RTEMS_PREEMPT | RTEMS_NO_TIMESLICE | RTEMS_NO_ASR |
    RTEMS_INTERRUPT_LEVEL(0),
    RTEMS_NO_FLOATING_POINT | RTEMS_LOCAL,
    &tid);

  if (sc == RTEMS_SUCCESSFUL)
  {
    sc = rtems_task_start(tid, daemon, 0);
    if (sc != RTEMS_SUCCESSFUL)
      rtems_task_delete(tid);
  }

  if (sc != RTEMS_SUCCESSFUL)
  {
    task_pool_done(count);
    syslog(LOG_ERR, "ftpd: Could not create/start FTP daemon: %s",
      rtems_status_text(sc));
    return RTEMS_UNSATISFIED;
  }

  ftpd_root = "/";
  if (
    rtems_ftpd_configuration.root &&
    rtems_ftpd_configuration.root[0] == '/'
  )
    ftpd_root = rtems_ftpd_configuration.root;

  rtems_ftpd_configuration.root = ftpd_root;

  syslog(LOG_INFO, "ftpd: FTP daemon started (%d session%s max)",
    count, ((count > 1) ? "s" : ""));

  return RTEMS_SUCCESSFUL;
}