ftp.c

Wget很好的处理了http和ftp的下载,很值得学习的经典代码

        }
      if (err != FTPRESTFAIL && !opt.server_response)
        logputs (LOG_VERBOSE, _("done.    "));
    } /* restval && cmd & DO_RETR */

  if (cmd & DO_RETR)
    {
      /* If we're in spider mode, don't really retrieve anything.  The
         fact that we got to this point should be proof enough that
         the file exists, vaguely akin to HTTP's concept of a "HEAD"
         request.  */
      if (opt.spider)
        {
          fd_close (csock);
          con->csock = -1;
          fd_close (dtsock);
          fd_close (local_sock);
          return RETRFINISHED;
        }

      if (opt.verbose)
        {
          if (!opt.server_response)
            {
              if (restval)
                logputs (LOG_VERBOSE, "\n");
              logprintf (LOG_VERBOSE, "==> RETR %s ... ", escnonprint (u->file));
            }
        }

      err = ftp_retr (csock, u->file);
      /* FTPRERR, WRITEFAILED, FTPNSFOD */
      switch (err)
        {
        case FTPRERR:
          logputs (LOG_VERBOSE, "\n");
          logputs (LOG_NOTQUIET, _("\
Error in server response, closing control connection.\n"));
          fd_close (csock);
          con->csock = -1;
          fd_close (dtsock);
          fd_close (local_sock);
          return err;
        case WRITEFAILED:
          logputs (LOG_VERBOSE, "\n");
          logputs (LOG_NOTQUIET,
                   _("Write failed, closing control connection.\n"));
          fd_close (csock);
          con->csock = -1;
          fd_close (dtsock);
          fd_close (local_sock);
          return err;
        case FTPNSFOD:
          logputs (LOG_VERBOSE, "\n");
          logprintf (LOG_NOTQUIET, _("No such file `%s'.\n\n"),
                     escnonprint (u->file));
          fd_close (dtsock);
          fd_close (local_sock);
          return err;
        case FTPOK:
          break;
        default:
          abort ();
        }

      if (!opt.server_response)
        logputs (LOG_VERBOSE, _("done.\n"));
      expected_bytes = ftp_expected_bytes (ftp_last_respline);
    } /* do retrieve */

  if (cmd & DO_LIST)
    {
      if (!opt.server_response)
        logputs (LOG_VERBOSE, "==> LIST ... ");
      /* As Maciej W. Rozycki ([e-mail]) says, `LIST'
         without arguments is better than `LIST .'; confirmed by
         RFC959.  */
      err = ftp_list (csock, NULL);
      /* FTPRERR, WRITEFAILED */
      switch (err)
        {
        case FTPRERR:
          logputs (LOG_VERBOSE, "\n");
          logputs (LOG_NOTQUIET, _("\
Error in server response, closing control connection.\n"));
          fd_close (csock);
          con->csock = -1;
          fd_close (dtsock);
          fd_close (local_sock);
          return err;
        case WRITEFAILED:
          logputs (LOG_VERBOSE, "\n");
          logputs (LOG_NOTQUIET,
                   _("Write failed, closing control connection.\n"));
          fd_close (csock);
          con->csock = -1;
          fd_close (dtsock);
          fd_close (local_sock);
          return err;
        case FTPNSFOD:
          logputs (LOG_VERBOSE, "\n");
          logprintf (LOG_NOTQUIET, _("No such file or directory `%s'.\n\n"),
                     ".");
          fd_close (dtsock);
          fd_close (local_sock);
          return err;
        case FTPOK:
          break;
        default:
          abort ();
        }
      if (!opt.server_response)
        logputs (LOG_VERBOSE, _("done.\n"));
      expected_bytes = ftp_expected_bytes (ftp_last_respline);
    } /* cmd & DO_LIST */

  if (!(cmd & (DO_LIST | DO_RETR)) || (opt.spider && !(cmd & DO_LIST)))
    return RETRFINISHED;

  /* Some FTP servers return the total length of file after REST
     command, others just return the remaining size. */
  if (*len && restval && expected_bytes
      && (expected_bytes == *len - restval))
    {
      DEBUGP (("Lying FTP server found, adjusting.\n"));
      expected_bytes = *len;
    }

  /* If no transmission was required, then everything is OK.  */
  if (!pasv_mode_open)  /* we are not using pasive mode so we need
                              to accept */
    {
      /* Wait for the server to connect to the address we're waiting
         at.  */
      dtsock = accept_connection (local_sock);
      if (dtsock < 0)
        {
          logprintf (LOG_NOTQUIET, "accept: %s\n", strerror (errno));
          return err;
        }
    }

  /* Open the file -- if output_stream is set, use it instead.  */
  if (!output_stream || con->cmd & DO_LIST)
    {
      mkalldirs (con->target);
      if (opt.backups)
        rotate_backups (con->target);

      if (restval)
        fp = fopen (con->target, "ab");
      else if (opt.noclobber || opt.always_rest || opt.timestamping || opt.dirstruct
               || opt.output_document)
        fp = fopen (con->target, "wb");
      else
        {
          fp = fopen_excl (con->target, true);
          if (!fp && errno == EEXIST)
            {
              /* We cannot just invent a new name and use it (which is
                 what functions like unique_create typically do)
                 because we told the user we'd use this name.
                 Instead, return and retry the download.  */
              logprintf (LOG_NOTQUIET, _("%s has sprung into existence.\n"),
                         con->target);
              fd_close (csock);
              con->csock = -1;
              fd_close (dtsock);
              fd_close (local_sock);
              return FOPEN_EXCL_ERR;
            }
        }
      if (!fp)
        {
          logprintf (LOG_NOTQUIET, "%s: %s\n", con->target, strerror (errno));
          fd_close (csock);
          con->csock = -1;
          fd_close (dtsock);
          fd_close (local_sock);
          return FOPENERR;
        }
    }
  else
    fp = output_stream;

  if (*len)
    {
      print_length (*len, restval, true);
      expected_bytes = *len;    /* for fd_read_body's progress bar */
    }
  else if (expected_bytes)
    print_length (expected_bytes, restval, false);

  /* Get the contents of the document.  */
  flags = 0;
  if (restval && rest_failed)
    flags |= rb_skip_startpos;
  *len = restval;
  rd_size = 0;
  res = fd_read_body (dtsock, fp,
                      expected_bytes ? expected_bytes - restval : 0,
                      restval, &rd_size, len, &con->dltime, flags);

  tms = datetime_str (time (NULL));
  tmrate = retr_rate (rd_size, con->dltime);
  total_download_time += con->dltime;

  fd_close (local_sock);
  /* Close the local file.  */
  if (!output_stream || con->cmd & DO_LIST)
    fclose (fp);

  /* If fd_read_body couldn't write to fp, bail out.  */
  if (res == -2)
    {
      logprintf (LOG_NOTQUIET, _("%s: %s, closing control connection.\n"),
                 con->target, strerror (errno));
      fd_close (csock);
      con->csock = -1;
      fd_close (dtsock);
      return FWRITEERR;
    }
  else if (res == -1)
    {
      logprintf (LOG_NOTQUIET, _("%s (%s) - Data connection: %s; "),
                 tms, tmrate, fd_errstr (dtsock));
      if (opt.server_response)
        logputs (LOG_ALWAYS, "\n");
    }
  fd_close (dtsock);

  /* Get the server to tell us if everything is retrieved.  */
  err = ftp_response (csock, &respline);
  if (err != FTPOK)
    {
      /* The control connection is decidedly closed.  Print the time
         only if it hasn't already been printed.  */
      if (res != -1)
        logprintf (LOG_NOTQUIET, "%s (%s) - ", tms, tmrate);
      logputs (LOG_NOTQUIET, _("Control connection closed.\n"));
      /* If there is an error on the control connection, close it, but
         return FTPRETRINT, since there is a possibility that the
         whole file was retrieved nevertheless (but that is for
         ftp_loop_internal to decide).  */
      fd_close (csock);
      con->csock = -1;
      return FTPRETRINT;
    } /* err != FTPOK */
  /* If retrieval failed for any reason, return FTPRETRINT, but do not
     close socket, since the control connection is still alive.  If
     there is something wrong with the control connection, it will
     become apparent later.  */
  if (*respline != '2')
    {
      xfree (respline);
      if (res != -1)
        logprintf (LOG_NOTQUIET, "%s (%s) - ", tms, tmrate);
      logputs (LOG_NOTQUIET, _("Data transfer aborted.\n"));
      return FTPRETRINT;
    }
  xfree (respline);

  if (res == -1)
    {
      /* What now?  The data connection was erroneous, whereas the
         response says everything is OK.  We shall play it safe.  */
      return FTPRETRINT;
    }

  if (!(cmd & LEAVE_PENDING))
    {
      /* Closing the socket is faster than sending 'QUIT' and the
         effect is the same.  */
      fd_close (csock);
      con->csock = -1;
    }
  /* If it was a listing, and opt.server_response is true,
     print it out.  */
  if (opt.server_response && (con->cmd & DO_LIST))
    {
      mkalldirs (con->target);
      fp = fopen (con->target, "r");
      if (!fp)
        logprintf (LOG_ALWAYS, "%s: %s\n", con->target, strerror (errno));
      else
        {
          char *line;
          /* The lines are being read with read_whole_line because of
             no-buffering on opt.lfile.  */
          while ((line = read_whole_line (fp)) != NULL)
            {
              char *p = strchr (line, '\0');
              while (p > line && (p[-1] == '\n' || p[-1] == '\r'))
                *--p = '\0';
              logprintf (LOG_ALWAYS, "%s\n", escnonprint (line));
              xfree (line);
            }
          fclose (fp);
        }
    } /* con->cmd & DO_LIST && server_response */

  return RETRFINISHED;
}

/* A one-file FTP loop.  This is the part where FTP retrieval is
   retried, and retried, and retried, and...

   This loop either gets commands from con, or (if ON_YOUR_OWN is
   set), makes them up to retrieve the file given by the URL.  */
static uerr_t
ftp_loop_internal (struct url *u, struct fileinfo *f, ccon *con)
{
  int count, orig_lp;
  wgint restval, len = 0;
  char *tms, *locf;
  const char *tmrate = NULL;
  uerr_t err;
  struct_stat st;

  if (!con->target)
    con->target = url_file_name (u);

  if (opt.noclobber && file_exists_p (con->target))
    {
      logprintf (LOG_VERBOSE,
                 _("File `%s' already there; not retrieving.\n"), con->target);
      /* If the file is there, we suppose it's retrieved OK.  */
      return RETROK;
    }

  /* Remove it if it's a link.  */
  remove_link (con->target);
  if (!opt.output_document)
    locf = con->target;
  else
    locf = opt.output_document;

  count = 0;

  if (con->st & ON_YOUR_OWN)
    con->st = ON_YOUR_OWN;

  orig_lp = con->cmd & LEAVE_PENDING ? 1 : 0;

  /* THE loop.  */
  do
    {
      /* Increment the pass counter.  */
      ++count;
      sleep_between_retrievals (count);
      if (con->st & ON_YOUR_OWN)
        {
          con->cmd = 0;
          con->cmd |= (DO_RETR | LEAVE_PENDING);
          if (con->csock != -1)
            con->cmd &= ~ (DO_LOGIN | DO_CWD);
          else
            con->cmd |= (DO_LOGIN | DO_CWD);
        }
      else /* not on your own */
        {
          if (con->csock != -1)
            con->cmd &= ~DO_LOGIN;
          else
            con->cmd |= DO_LOGIN;
          if (con->st & DONE_CWD)
            con->cmd &= ~DO_CWD;
          else
            con->cmd |= DO_CWD;
        }

      /* Decide whether or not to restart.  */
      if (opt.always_rest
          && stat (locf, &st) == 0
          && S_ISREG (st.st_mode))
        /* When -c is used, continue from on-disk size.  (Can't use
           hstat.len even if count>1 because we don't want a failed
           first attempt to clobber existing data.)  */
        restval = st.st_size;
      else if (count > 1)
        restval = len;          /* start where the previous run left off */
      else
        restval = 0;

      /* Get the current time string.  */
      tms = datetime_str (time (NULL));