ftpd.c

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

      fd = creat(filename,
        S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH);

    if (0 > fd)
    {
      send_reply(info, 550, "Error creating file.");
      close_data_socket(info);
      return;
    }

    if(info->xfer_mode == TYPE_I)
    {
      while ((n = recv(s, buf, FTPD_DATASIZE, 0)) > 0)
      {
        if (wrt(fd, buf, n) != n)
        {
          res = 0;
          break;
        }
      }
    }
    else if(info->xfer_mode == TYPE_A)
    {
      int rest = 0;
      int pended_cr = 0;
      while (res && rest == 0 && (n = recv(s, buf, FTPD_DATASIZE, 0)) > 0)
      {
        char const* e = buf;
        char const* b;
        int i;

        rest = n;
        if(pended_cr && *e != '\n')
        {
          char const lf = '\r';
          pended_cr = 0;
          if(wrt(fd, &lf, 1) != 1)
          {
            res = 0;
            break;
          }
        }
        do
        {
          int count;
          int sub = 0;

          b = e;
          for(i = 0; i < rest; ++i, ++e)
          {
            int pcr = pended_cr;
            pended_cr = 0;
            if(*e == '\r')
            {
              pended_cr = 1;
            }
            else if(*e == '\n')
            {
              if(pcr)
              {
                sub = 2;
                ++i;
                ++e;
                break;
              }
              ++bare_lfs;
            }
          }
          if(res == 0)
            break;
          count = i - sub - pended_cr;
          if(count > 0 && wrt(fd, b, count) != count)
          {
            res = 0;
            break;
          }
          if(sub == 2 && wrt(fd, e - 1, 1) != 1)
            res = 0;
        }
        while((rest -= i) > 0);
      }
    }

    if (0 > close(fd) || res == 0)
    {
      send_reply(info, 452, "Error writing file.");
      close_data_socket(info);
      return;
    }
  }

  if (bare_lfs > 0)
  {
    snprintf(buf, FTPD_BUFSIZE,
      "Transfer complete. WARNING! %d bare linefeeds received in ASCII mode.",
      bare_lfs);
    send_reply(info, 226, buf);
  }
  else
    send_reply(info, 226, "Transfer complete.");
  close_data_socket(info);

}


/*PAGE
 *
 * send_dirline
 *
 * Sends one line of LIST command reply corresponding to single file.
 *
 * Input parameters:
 *   s - socket descriptor to send data to
 *   wide - if 0, send only file name.  If not 0, send 'stat' info as well in
 *          "ls -l" format.
 *   curTime - current time
 *   path - path to be prepended to what is given by 'add'
 *   add  - path to be appended to what is given by 'path', the resulting path
 *          is then passed to 'stat()' routine
 *   name - file name to be reported in output
 *   buf  - buffer for temporary data
 *
 * Output parameters:
 *   returns 0 on failure, 1 on success
 *
 */
static int
send_dirline(int s, int wide, time_t curTime, char const* path,
  char const* add, char const* fname, char* buf)
{
  if(wide)
  {
    struct stat stat_buf;

    int plen = strlen(path);
    int alen = strlen(add);
    if(plen == 0)
    {
      buf[plen++] = '/';
      buf[plen] = '\0';
    }
    else
    {
      strcpy(buf, path);
      if(alen > 0 && buf[plen - 1] != '/')
      {
        buf[plen++] = '/';
        if(plen >= FTPD_BUFSIZE)
          return 0;
        buf[plen] = '\0';
      }
    }
    if(plen + alen >= FTPD_BUFSIZE)
      return 0;
    strcpy(buf + plen, add);

    if (stat(buf, &stat_buf) == 0)
    {
      int len;
      struct tm bt;
      time_t tf = stat_buf.st_mtime;
      enum { SIZE = 80 };
      enum { SIX_MONTHS = 365*24*60*60/2 };
      char timeBuf[SIZE];
      gmtime_r(&tf, &bt);
      if(curTime > tf + SIX_MONTHS || tf > curTime + SIX_MONTHS)
        strftime (timeBuf, SIZE, "%b %d  %Y", &bt);
      else
        strftime (timeBuf, SIZE, "%b %d %H:%M", &bt);

      len = snprintf(buf, FTPD_BUFSIZE,
        "%c%c%c%c%c%c%c%c%c%c  1 %5d %5d %11u %s %s\r\n",
        (S_ISLNK(stat_buf.st_mode)?('l'):
          (S_ISDIR(stat_buf.st_mode)?('d'):('-'))),
        (stat_buf.st_mode & S_IRUSR)?('r'):('-'),
        (stat_buf.st_mode & S_IWUSR)?('w'):('-'),
        (stat_buf.st_mode & S_IXUSR)?('x'):('-'),
        (stat_buf.st_mode & S_IRGRP)?('r'):('-'),
        (stat_buf.st_mode & S_IWGRP)?('w'):('-'),
        (stat_buf.st_mode & S_IXGRP)?('x'):('-'),
        (stat_buf.st_mode & S_IROTH)?('r'):('-'),
        (stat_buf.st_mode & S_IWOTH)?('w'):('-'),
        (stat_buf.st_mode & S_IXOTH)?('x'):('-'),
        (int)stat_buf.st_uid,
        (int)stat_buf.st_gid,
        (int)stat_buf.st_size,
        timeBuf,
        fname
      );

      if(send(s, buf, len, 0) != len)
        return 0;
    }
  }
  else
  {
    int len = snprintf(buf, FTPD_BUFSIZE, "%s\r\n", fname);
    if(send(s, buf, len, 0) != len)
      return 0;
  }
  return 1;
}

/*PAGE
 *
 * command_list
 *
 * Send file list to client.
 *
 * Input parameters:
 *   info - corresponding SessionInfo structure
 *   char *fname  - File (or directory) to list.
 *
 * Output parameters:
 *   NONE
 */
static void
command_list(FTPD_SessionInfo_t *info, char const *fname, int wide)
{
  int                 s;
  DIR                 *dirp = 0;
  struct dirent       *dp = 0;
  struct stat         stat_buf;
  char                buf[FTPD_BUFSIZE];
  time_t curTime;
  int sc = 1;

  send_reply(info, 150, "Opening ASCII mode data connection for LIST.");

  s = data_socket(info);
  if(0 > s)
  {
    syslog(LOG_ERR, "ftpd: Error connecting to data socket.");
    return;
  }

  if(fname[0] == '\0')
    fname = ".";

  if (0 > stat(fname, &stat_buf))
  {
    snprintf(buf, FTPD_BUFSIZE,
      "%s: No such file or directory.\r\n", fname);
    send(s, buf, strlen(buf), 0);
  }
  else if (S_ISDIR(stat_buf.st_mode) && (NULL == (dirp = opendir(fname))))
  {
    snprintf(buf, FTPD_BUFSIZE,
      "%s: Can not open directory.\r\n", fname);
    send(s, buf, strlen(buf), 0);
  }
  else
  {
    time(&curTime);
    if(!dirp && *fname)
      sc = sc && send_dirline(s, wide, curTime, fname, "", fname, buf);
    else {
      /* FIXME: need "." and ".." only when '-a' option is given */
      sc = sc && send_dirline(s, wide, curTime, fname, "", ".", buf);
      sc = sc && send_dirline(s, wide, curTime, fname,
        (strcmp(fname, ftpd_root) ? ".." : ""), "..", buf);
      while (sc && (dp = readdir(dirp)) != NULL)
        sc = sc &&
          send_dirline(s, wide, curTime, fname, dp->d_name, dp->d_name, buf);
    }
  }

  if(dirp)
    closedir(dirp);
  close_data_socket(info);

  if(sc)
    send_reply(info, 226, "Transfer complete.");
  else
    send_reply(info, 426, "Connection aborted.");
}


/*PAGE
 *
 * command_cwd
 *
 * Change current working directory.
 *
 * Input parameters:
 *   info - corresponding SessionInfo structure
 *   dir  - directory name passed in CWD command
 *
 * Output parameters:
 *   NONE
 *
 */
static void
command_cwd(FTPD_SessionInfo_t  *info, char *dir)
{
  if(chdir(dir) == 0)
    send_reply(info, 250, "CWD command successful.");
  else
    send_reply(info, 550, "CWD command failed.");
}


/*PAGE
 *
 * command_pwd
 *
 * Send current working directory to client.
 *
 * Input parameters:
 *   info - corresponding SessionInfo structure
 *
 * Output parameters:
 *   NONE
 */
static void
command_pwd(FTPD_SessionInfo_t  *info)
{
  char buf[FTPD_BUFSIZE];
  char const* cwd;
  errno = 0;
  buf[0] = '"';
  cwd = getcwd(buf + 1, FTPD_BUFSIZE - 4);
  if(cwd)
  {
    int len = strlen(cwd);
    static char const txt[] = "\" is the current directory.";
    int size = sizeof(txt);
    if(len + size + 1 >= FTPD_BUFSIZE)
      size = FTPD_BUFSIZE - len - 2;
    memcpy(buf + len + 1, txt, size);
    buf[len + size] = '\0';
    send_reply(info, 250, buf);
  }
  else {
    snprintf(buf, FTPD_BUFSIZE, "Error: %s.", serr());
    send_reply(info, 452, buf);
  }
}

/*PAGE
 *
 * command_mdtm
 *
 * Handle FTP MDTM command (send file modification time to client)/
 *
 * Input parameters:
 *   info - corresponding SessionInfo structure
 *   fname - file name passed in MDTM command
 *
 * Output parameters:
 *   info->cwd is set to new CWD value.
 */
static void
command_mdtm(FTPD_SessionInfo_t  *info, char const* fname)
{
  struct stat stbuf;
  char buf[FTPD_BUFSIZE];

  if (0 > stat(fname, &stbuf))
  {
    snprintf(buf, FTPD_BUFSIZE, "%s: %s.", fname, serr());
    send_reply(info, 550, buf);
  }
  else
  {
    struct tm *t = gmtime(&stbuf.st_mtime);
    snprintf(buf, FTPD_BUFSIZE, "%04d%02d%02d%02d%02d%02d",
      1900 + t->tm_year,
      t->tm_mon+1, t->tm_mday,
      t->tm_hour, t->tm_min, t->tm_sec);
    send_reply(info, 213, buf);
  }
}

/*PAGE
 *
 * command_port
 *
 * This procedure fills address for data connection given the IP address and
 * port of the remote machine.
 *
 * Input parameters:
 *   info - corresponding SessionInfo structure
 *   args - arguments to the "PORT" command.
 *
 * Output parameters:
 *   info->data_addr is set according to arguments of the PORT command.
 *   info->use_default is set to 0 on success, 1 on failure.
 */
static void
command_port(FTPD_SessionInfo_t *info, char const *args)
{
  enum { NUM_FIELDS = 6 };
  unsigned int a[NUM_FIELDS];
  int n;

  close_data_socket(info);

  n = sscanf(args, "%u,%u,%u,%u,%u,%u", a+0, a+1, a+2, a+3, a+4, a+5);
  if(NUM_FIELDS == n)
  {
    int i;
    unsigned8 b[NUM_FIELDS];

    for(i = 0; i < NUM_FIELDS; ++i)
    {
      if(a[i] > 255)
        break;
      b[i] = (unsigned8)a[i];
    }

    if(i == NUM_FIELDS)
    {
      /* Note: while it contradicts with RFC959, we don't allow PORT command
       * to specify IP address different than those of the originating client
       * for the sake of safety. */
      unsigned32 const *ip   = (unsigned32 *)b;
      if(*ip == info->def_addr.sin_addr.s_addr)
      {
        info->data_addr.sin_addr.s_addr = *ip;
        info->data_addr.sin_port        = *(unsigned16 *)(b + 4);
        info->data_addr.sin_family      = AF_INET;
        memset(info->data_addr.sin_zero, 0, sizeof(info->data_addr.sin_zero));

        info->use_default = 0;
        send_reply(info, 200, "PORT command successful.");
        return; /* success */
      }
      else
      {
        send_reply(info, 425, "Address doesn't match peer's IP.");
        return;
      }
    }
  }
  send_reply(info, 501, "Syntax error.");
}


/*PAGE
 *
 * command_pasv
 *
 * Handle FTP PASV command.
 * Open socket, listen for and accept connection on it.
 *
 * Input parameters:
 *   info - corresponding SessionInfo structure
 *
 * Output parameters:
 *   info->pasv_socket is set to the descriptor of the data socket
 */
static void
command_pasv(FTPD_SessionInfo_t *info)
{
  int s = -1;
  int err = 1;

  close_data_socket(info);

  s = socket(PF_INET, SOCK_STREAM, 0);
  if (s < 0)
    syslog(LOG_ERR, "ftpd: Error creating PASV socket: %s", serr());
  else
  {
    struct sockaddr_in addr;
    int addrLen = sizeof(addr);

    addr = info->ctrl_addr;
    addr.sin_port = htons(0);

    if (0 > bind(s, (struct sockaddr *)&addr, addrLen))
      syslog(LOG_ERR, "ftpd: Error binding PASV socket: %s", serr());
    else if (0 > listen(s, 1))
      syslog(LOG_ERR, "ftpd: Error listening on PASV socket: %s", serr());
    else if(set_socket_timeout(s, info->idle))
    {
      char buf[FTPD_BUFSIZE];
      unsigned char const *ip, *p;

      getsockname(s, (struct sockaddr *)&addr, &addrLen);
      ip = (unsigned char const*)&(addr.sin_addr);
      p  = (unsigned char const*)&(addr.sin_port);
      snprintf(buf, FTPD_BUFSIZE, "Entering passive mode (%u,%u,%u,%u,%u,%u).",
        ip[0], ip[1], ip[2], ip[3], p[0], p[1]);
      send_reply(info, 227, buf);

      info->pasv_socket = accept(s, (struct sockaddr *)&addr, &addrLen);
      if (0 > info->pasv_socket)
        syslog(LOG_ERR, "ftpd: Error accepting PASV connection: %s", serr());
      else
      {
        close_socket(s);
        s = -1;
        err = 0;
      }
    }
  }
  if(err)
  {
    /* (OSV) The note is from FreeBSD FTPD.
     * Note: a response of 425 is not mentioned as a possible response to
     * the PASV command in RFC959.  However, it has been blessed as a
     * legitimate response by Jon Postel in a telephone conversation
     * with Rick Adams on 25 Jan 89. */
    send_reply(info, 425, "Can't open passive connection.");
    close_socket(s);
  }
}


/*PAGE
 *
 * skip_options
 *
 * Utility routine to skip options (if any) from input command.