gnupg/g10/plaintext.c

/* plaintext.c -  process plaintext packets
 * Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
 *               2006, 2009, 2010 Free Software Foundation, Inc.
 *
 * This file is part of GnuPG.
 *
 * GnuPG is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
 * GnuPG is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, see <https://www.gnu.org/licenses/>.
 */

#include <config.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <sys/types.h>
#ifdef HAVE_DOSISH_SYSTEM
# include <fcntl.h> /* for setmode() */
#endif

#include "gpg.h"
#include "../common/util.h"
#include "options.h"
#include "packet.h"
#include "../common/ttyio.h"
#include "filter.h"
#include "main.h"
#include "../common/status.h"
#include "../common/i18n.h"


/* Get the output filename.  On success, the actual filename that is
   used is set in *FNAMEP and a filepointer is returned in *FP.

   EMBEDDED_NAME AND EMBEDDED_NAMELEN are normally stored in a
   plaintext packet.  EMBEDDED_NAMELEN should not include any NUL
   terminator (EMBEDDED_NAME does not need to be NUL terminated).

   DATA is the iobuf containing the input data.  We just use it to get
   the input file's filename.

   On success, the caller is responsible for calling xfree on *FNAMEP
   and calling es_close on *FPP.  */
gpg_error_t
get_output_file (const byte *embedded_name, int embedded_namelen,
                 iobuf_t data, char **fnamep, estream_t *fpp)
{
  gpg_error_t err = 0;
  char *fname = NULL;
  estream_t fp = NULL;
  int nooutput = 0;

  /* Create the filename as C string.  */
  if (opt.outfp)
    {
      fname = xtrystrdup ("[FP]");
      if (!fname)
        {
          err = gpg_error_from_syserror ();
          goto leave;
        }
    }
  else if (opt.outfile
           && !(opt.flags.use_embedded_filename && opt.flags.dummy_outfile))
    {
      fname = xtrystrdup (opt.outfile);
      if (!fname)
        {
          err = gpg_error_from_syserror ();
          goto leave;
        }
    }
  else if (embedded_namelen == 8 && !memcmp (embedded_name, "_CONSOLE", 8))
    {
      log_info (_("data not saved; use option \"--output\" to save it\n"));
      nooutput = 1;
    }
  else if (!opt.flags.use_embedded_filename)
    {
      if (data)
        fname = make_outfile_name (iobuf_get_real_fname (data));
      if (!fname)
	fname = ask_outfile_name (embedded_name, embedded_namelen);
      if (!fname)
	{
	  err = gpg_error (GPG_ERR_GENERAL);	/* Can't create file. */
	  goto leave;
	}
    }
  else
    fname = utf8_to_native (embedded_name, embedded_namelen, 0);

  if (nooutput)
    ;
  else if (opt.outfp)
    {
      fp = opt.outfp;
      es_set_binary (fp);
    }
  else if (iobuf_is_pipe_filename (fname) || !*fname)
    {
      /* Special file name, no filename, or "-" given; write to the
       * file descriptor or to stdout. */
      gnupg_fd_t fd;
      char xname[64];

      fd = gnupg_check_special_filename (fname);
      if (fd == GNUPG_INVALID_FD)
        {
          /* Not a special filename, thus we want stdout.  */
          fp = es_stdout;
          es_set_binary (fp);
        }
      else if (!(fp = open_stream_nc (fd, "wb")))
        {
          err = gpg_error_from_syserror ();
          snprintf (xname, sizeof xname, "[fd %d]", FD_DBG (fd));
          log_error (_("can't open '%s': %s\n"), xname, gpg_strerror (err));
          goto leave;
        }
    }
  else
    {
      while (!overwrite_filep (fname))
	{
	  char *tmp = ask_outfile_name (NULL, 0);
	  if (!tmp || !*tmp)
	    {
	      xfree (tmp);
              err = gpg_error (GPG_ERR_EEXIST);
	      goto leave;
	    }
	  xfree (fname);
	  fname = tmp;
	}
    }

  if (fp || nooutput)
    ;
  else if (is_secured_filename (fname))
    {
      gpg_err_set_errno (EPERM);
      err = gpg_error_from_syserror ();
      log_error (_("error creating '%s': %s\n"), fname, gpg_strerror (err));
      goto leave;
    }
  else if (!(fp = es_fopen (fname, "wb")))
    {
      err = gpg_error_from_syserror ();
      log_error (_("error creating '%s': %s\n"), fname, gpg_strerror (err));
      goto leave;
    }

 leave:
  if (err)
    {
      if (fp && fp != es_stdout && fp != opt.outfp)
        es_fclose (fp);
      xfree (fname);
      return err;
    }

  *fnamep = fname;
  *fpp = fp;
  return 0;
}

/* Handle a plaintext packet.  If MFX is not NULL, update the MDs
 * Note: We should have used the filter stuff here, but we have to add
 * some easy mimic to set a read limit, so we calculate only the bytes
 * from the plaintext.  */
int
handle_plaintext (PKT_plaintext * pt, md_filter_context_t * mfx,
		  int nooutput, int clearsig)
{
  char *fname = NULL;
  estream_t fp = NULL;
  static off_t count = 0;
  int err = 0;
  int c;
  int convert;
#ifdef __riscos__
  int filetype = 0xfff;
#endif

  if (pt->mode == 't' || pt->mode == 'u' || pt->mode == 'm')
    convert = pt->mode;
  else
    convert = 0;

  /* Let people know what the plaintext info is. This allows the
     receiving program to try and do something different based on the
     format code (say, recode UTF-8 to local). */
  if (!nooutput && is_status_enabled ())
    {
      char status[50];

      /* Better make sure that stdout has been flushed in case the
         output will be written to it.  This is to make sure that no
         not-yet-flushed stuff will be written after the plaintext
         status message.  */
      es_fflush (es_stdout);

      snprintf (status, sizeof status,
                "%X %lu ", (byte) pt->mode, (ulong) pt->timestamp);
      write_status_text_and_buffer (STATUS_PLAINTEXT,
				    status, pt->name, pt->namelen, 0);

      if (!pt->is_partial)
	{
	  snprintf (status, sizeof status, "%lu", (ulong) pt->len);
	  write_status_text (STATUS_PLAINTEXT_LENGTH, status);
	}
    }

  if (! nooutput)
    {
      err = get_output_file (pt->name, pt->namelen, pt->buf, &fname, &fp);
      if (err)
        goto leave;
    }

  if (!pt->is_partial)
    {
      /* We have an actual length (which might be zero). */

      if (clearsig)
	{
	  log_error ("clearsig encountered while not expected\n");
	  err = gpg_error (GPG_ERR_UNEXPECTED);
	  goto leave;
	}

      if (convert) /* Text mode.  */
	{
	  for (; pt->len; pt->len--)
	    {
	      if ((c = iobuf_get (pt->buf)) == -1)
		{
		  err = gpg_error_from_syserror ();
		  log_error ("problem reading source (%u bytes remaining)\n",
			     (unsigned) pt->len);
		  goto leave;
		}
	      if (mfx->md)
		gcry_md_putc (mfx->md, c);
#ifndef HAVE_DOSISH_SYSTEM
              /* Convert to native line ending. */
              /* fixme: this hack might be too simple */
	      if (c == '\r' && convert != 'm')
		continue;
#endif
	      if (fp)
		{
		  if (opt.max_output && (++count) > opt.max_output)
		    {
		      log_error ("error writing to '%s': %s\n",
				 fname, "exceeded --max-output limit\n");
		      err = gpg_error (GPG_ERR_TOO_LARGE);
		      goto leave;
		    }
		  else if (es_putc (c, fp) == EOF)
		    {
		      if (es_ferror (fp))
			err = gpg_error_from_syserror ();
		      else
			err = gpg_error (GPG_ERR_EOF);
		      log_error ("error writing to '%s': %s\n",
				 fname, gpg_strerror (err));
		      goto leave;
		    }
		}
	    }
	}
      else  /* Binary mode.  */
	{
	  size_t temp_size = iobuf_set_buffer_size(0) * 1024;
	  byte *buffer;

	  if (fp)
	    {
	      /* Disable buffering in estream as we are passing large
	       * buffers to es_fwrite. */
	      es_setbuf (fp, NULL);
	    }

	  buffer = xmalloc (temp_size);
          if (!buffer)
            {
              err = gpg_error_from_syserror ();
              goto leave;
            }

	  while (pt->len)
	    {
	      int len = pt->len > temp_size ? temp_size : pt->len;
	      len = iobuf_read (pt->buf, buffer, len);
	      if (len == -1)
		{
		  err = gpg_error_from_syserror ();
		  log_error ("problem reading source (%u bytes remaining)\n",
			     (unsigned) pt->len);
		  xfree (buffer);
		  goto leave;
		}
	      if (mfx->md)
		gcry_md_write (mfx->md, buffer, len);
	      if (fp)
		{
		  if (opt.max_output && (count += len) > opt.max_output)
		    {
		      log_error ("error writing to '%s': %s\n",
				 fname, "exceeded --max-output limit\n");
		      err = gpg_error (GPG_ERR_TOO_LARGE);
		      xfree (buffer);
		      goto leave;
		    }
		  else if (es_fwrite (buffer, 1, len, fp) != len)
		    {
		      err = gpg_error_from_syserror ();
		      log_error ("error writing to '%s': %s\n",
				 fname, gpg_strerror (err));
		      xfree (buffer);
		      goto leave;
		    }
		}
	      pt->len -= len;
	    }
	  xfree (buffer);
	}
    }
  else if (!clearsig)
    {
      if (convert)
	{			/* text mode */
	  while ((c = iobuf_get (pt->buf)) != -1)
	    {
	      if (mfx->md)
		gcry_md_putc (mfx->md, c);
#ifndef HAVE_DOSISH_SYSTEM
	      if (c == '\r' && convert != 'm')
		continue;	/* fixme: this hack might be too simple */
#endif
	      if (fp)
		{
		  if (opt.max_output && (++count) > opt.max_output)
		    {
		      log_error ("Error writing to '%s': %s\n",
				 fname, "exceeded --max-output limit\n");
		      err = gpg_error (GPG_ERR_TOO_LARGE);
		      goto leave;
		    }
		  else if (es_putc (c, fp) == EOF)
		    {
		      if (es_ferror (fp))
			err = gpg_error_from_syserror ();
		      else
			err = gpg_error (GPG_ERR_EOF);
		      log_error ("error writing to '%s': %s\n",
				 fname, gpg_strerror (err));
		      goto leave;
		    }
		}
	    }
	}
      else
	{			/* binary mode */
	  size_t temp_size = iobuf_set_buffer_size(0) * 1024;
	  byte *buffer;
	  int eof_seen = 0;

	  if (fp)
	    {
	      /* Disable buffering in estream as we are passing large
	       * buffers to es_fwrite. */
	      es_setbuf (fp, NULL);
	    }

          buffer = xtrymalloc (temp_size);
          if (!buffer)
            {
              err = gpg_error_from_syserror ();
              goto leave;
            }

	  while (!eof_seen)
	    {
	      /* Why do we check for len < temp_size:
	       * If we won't, we would practically read 2 EOFs but
	       * the first one has already popped the block_filter
	       * off and therefore we don't catch the boundary.
	       * So, always assume EOF if iobuf_read returns less bytes
	       * then requested */
	      int len = iobuf_read (pt->buf, buffer, temp_size);
	      if (len == -1)
		break;
	      if (len < temp_size)
		eof_seen = 1;
	      if (mfx->md)
		gcry_md_write (mfx->md, buffer, len);
	      if (fp)
		{
		  if (opt.max_output && (count += len) > opt.max_output)
		    {
		      log_error ("error writing to '%s': %s\n",
				 fname, "exceeded --max-output limit\n");
		      err = gpg_error (GPG_ERR_TOO_LARGE);
		      xfree (buffer);
		      goto leave;
		    }
		  else if (es_fwrite (buffer, 1, len, fp) != len)
		    {
		      err = gpg_error_from_syserror ();
		      log_error ("error writing to '%s': %s\n",
				 fname, gpg_strerror (err));
		      xfree (buffer);
		      goto leave;
		    }
		}
	    }
	  xfree (buffer);
	}
      pt->buf = NULL;
    }
  else /* Clear text signature - don't hash the last CR,LF.   */
    {
      int state = 0;

      while ((c = iobuf_get (pt->buf)) != -1)
	{
	  if (fp)
	    {
	      if (opt.max_output && (++count) > opt.max_output)
		{
		  log_error ("error writing to '%s': %s\n",
			     fname, "exceeded --max-output limit\n");
		  err = gpg_error (GPG_ERR_TOO_LARGE);
		  goto leave;
		}
	      else if (es_putc (c, fp) == EOF)
		{
		  err = gpg_error_from_syserror ();
		  log_error ("error writing to '%s': %s\n",
			     fname, gpg_strerror (err));
		  goto leave;
		}
	    }
	  if (!mfx->md)
	    continue;
	  if (state == 2)
	    {
	      gcry_md_putc (mfx->md, '\r');
	      gcry_md_putc (mfx->md, '\n');
	      state = 0;
	    }
	  if (!state)
	    {
	      if (c == '\r')
		state = 1;
	      else if (c == '\n')
		state = 2;
	      else
		gcry_md_putc (mfx->md, c);
	    }
	  else if (state == 1)
	    {
	      if (c == '\n')
		state = 2;
	      else
		{
		  gcry_md_putc (mfx->md, '\r');
		  if (c == '\r')
		    state = 1;
		  else
		    {
		      state = 0;
		      gcry_md_putc (mfx->md, c);
		    }
		}
	    }
	}
      pt->buf = NULL;
    }

  if (fp && fp != es_stdout && fp != opt.outfp && es_fclose (fp))
    {
      err = gpg_error_from_syserror ();
      log_error ("error closing '%s': %s\n", fname, gpg_strerror (err));
      fp = NULL;
      goto leave;
    }
  fp = NULL;

 leave:
  /* Make sure that stdout gets flushed after the plaintext has been
     handled.  This is for extra security as we do a flush anyway
     before checking the signature.  */
  if (es_fflush (es_stdout))
    {
      /* We need to check the return code to detect errors like disk
         full for short plaintexts.  See bug#1207.  Checking return
         values is a good idea in any case.  */
      if (!err)
        err = gpg_error_from_syserror ();
      log_error ("error flushing '%s': %s\n", "[stdout]",
                 gpg_strerror (err));
    }

  if (fp && fp != es_stdout && fp != opt.outfp)
    es_fclose (fp);
  xfree (fname);
  return err;
}


static void
do_hash (gcry_md_hd_t md, gcry_md_hd_t md2, IOBUF fp, int textmode)
{
  text_filter_context_t tfx;
  int c;

  if (textmode)
    {
      memset (&tfx, 0, sizeof tfx);
      iobuf_push_filter (fp, text_filter, &tfx);
    }
  if (md2)
    {				/* work around a strange behaviour in pgp2 */
      /* It seems that at least PGP5 converts a single CR to a CR,LF too */
      int lc = -1;
      while ((c = iobuf_get (fp)) != -1)
	{
	  if (c == '\n' && lc == '\r')
	    gcry_md_putc (md2, c);
	  else if (c == '\n')
	    {
	      gcry_md_putc (md2, '\r');
	      gcry_md_putc (md2, c);
	    }
	  else if (c != '\n' && lc == '\r')
	    {
	      gcry_md_putc (md2, '\n');
	      gcry_md_putc (md2, c);
	    }
	  else
	    gcry_md_putc (md2, c);

	  if (md)
	    gcry_md_putc (md, c);
	  lc = c;
	}
    }
  else
    {
      size_t temp_size = iobuf_set_buffer_size(0) * 1024;
      byte *buffer = xmalloc (temp_size);
      int ret;

      while ((ret = iobuf_read (fp, buffer, temp_size)) != -1)
	{
	  if (md)
	    gcry_md_write (md, buffer, ret);
	}

      xfree (buffer);
    }
}


/****************
 * Ask for the detached datafile and calculate the digest from it.
 * INFILE is the name of the input file.
 */
int
ask_for_detached_datafile (gcry_md_hd_t md, gcry_md_hd_t md2,
			   const char *inname, int textmode)
{
  progress_filter_context_t *pfx;
  char *answer = NULL;
  IOBUF fp;
  int rc = 0;

  pfx = new_progress_context ();
  fp = open_sigfile (inname, pfx);	/* Open default file. */

  if (!fp && !opt.batch)
    {
      int any = 0;
      tty_printf (_("Detached signature.\n"));
      do
	{
	  char *name;

	  xfree (answer);
	  tty_enable_completion (NULL);
	  name = cpr_get ("detached_signature.filename",
			  _("Please enter name of data file: "));
	  tty_disable_completion ();
	  cpr_kill_prompt ();
	  answer = make_filename (name, (void *) NULL);
	  xfree (name);

	  if (any && !*answer)
	    {
	      rc = gpg_error (GPG_ERR_GENERAL);	/*G10ERR_READ_FILE */
	      goto leave;
	    }
	  fp = iobuf_open (answer);
	  if (fp && is_secured_file (iobuf_get_fd (fp)))
	    {
	      iobuf_close (fp);
	      fp = NULL;
	      gpg_err_set_errno (EPERM);
	    }
	  if (!fp && errno == ENOENT)
	    {
	      tty_printf ("No such file, try again or hit enter to quit.\n");
	      any++;
	    }
	  else if (!fp)
	    {
	      rc = gpg_error_from_syserror ();
	      log_error (_("can't open '%s': %s\n"), answer,
			 strerror (errno));
	      goto leave;
	    }
	}
      while (!fp);
    }

  if (!fp)
    {
      if (opt.verbose)
	log_info (_("reading stdin ...\n"));
      fp = iobuf_open (NULL);
      log_assert (fp);
    }
  do_hash (md, md2, fp, textmode);
  iobuf_close (fp);

leave:
  xfree (answer);
  release_progress_context (pfx);
  return rc;
}



/* Hash the given files and append the hash to hash contexts MD and
 * MD2.  If FILES is NULL, stdin is hashed.  */
int
hash_datafiles (gcry_md_hd_t md, gcry_md_hd_t md2, strlist_t files,
		const char *sigfilename, int textmode)
{
  progress_filter_context_t *pfx;
  IOBUF fp;
  strlist_t sl;

  pfx = new_progress_context ();

  if (!files)
    {
      /* Check whether we can open the signed material.  We avoid
         trying to open a file if run in batch mode.  This assumed
         data file for a sig file feature is just a convenience thing
         for the command line and the user needs to read possible
         warning messages. */
      if (!opt.batch)
        {
          fp = open_sigfile (sigfilename, pfx);
          if (fp)
            {
              do_hash (md, md2, fp, textmode);
              iobuf_close (fp);
              release_progress_context (pfx);
              return 0;
            }
        }
      log_error (_("no signed data\n"));
      release_progress_context (pfx);
      return gpg_error (GPG_ERR_NO_DATA);
    }


  for (sl = files; sl; sl = sl->next)
    {
      fp = iobuf_open (sl->d);
      if (fp && is_secured_file (iobuf_get_fd (fp)))
	{
	  iobuf_close (fp);
	  fp = NULL;
	  gpg_err_set_errno (EPERM);
	}
      if (!fp)
	{
	  int rc = gpg_error_from_syserror ();
	  log_error (_("can't open signed data '%s'\n"),
		     print_fname_stdin (sl->d));
	  release_progress_context (pfx);
	  return rc;
	}
      handle_progress (pfx, fp, sl->d);
      do_hash (md, md2, fp, textmode);
      iobuf_close (fp);
    }

  release_progress_context (pfx);
  return 0;
}


/* Hash the data from file descriptor DATA_FD and append the hash to hash
   contexts MD and MD2.  */
int
hash_datafile_by_fd (gcry_md_hd_t md, gcry_md_hd_t md2,
                     gnupg_fd_t data_fd, int textmode)
{
  progress_filter_context_t *pfx = new_progress_context ();
  iobuf_t fp;

  if (is_secured_file (data_fd))
    {
      fp = NULL;
      gpg_err_set_errno (EPERM);
    }
  else
    fp = iobuf_fdopen_nc (data_fd, "rb");

  if (!fp)
    {
      int rc = gpg_error_from_syserror ();
      log_error (_("can't open signed data fd=%d: %s\n"),
		 FD_DBG (data_fd), strerror (errno));
      release_progress_context (pfx);
      return rc;
    }

  handle_progress (pfx, fp, NULL);

  do_hash (md, md2, fp, textmode);

  iobuf_close (fp);

  release_progress_context (pfx);
  return 0;
}


/* Set up a plaintext packet with the appropriate filename.  If there
   is a --set-filename, use it (it's already UTF8).  If there is a
   regular filename, UTF8-ize it if necessary.  If there is no
   filenames at all, set the field empty. */

PKT_plaintext *
setup_plaintext_name (const char *filename, IOBUF iobuf)
{
  PKT_plaintext *pt;

  if ((filename && !iobuf_is_pipe_filename (filename))
       || (opt.set_filename && !iobuf_is_pipe_filename (opt.set_filename)))
    {
      char *s;

      if (opt.set_filename)
	s = make_basename (opt.set_filename, iobuf_get_real_fname (iobuf));
      else if (filename && !opt.flags.utf8_filename)
	{
	  char *tmp = native_to_utf8 (filename);
	  s = make_basename (tmp, iobuf_get_real_fname (iobuf));
	  xfree (tmp);
	}
      else
	s = make_basename (filename, iobuf_get_real_fname (iobuf));

      pt = xmalloc (sizeof *pt + strlen (s) - 1);
      pt->namelen = strlen (s);
      memcpy (pt->name, s, pt->namelen);
      xfree (s);
    }
  else
    {
      /* no filename */
      pt = xmalloc (sizeof *pt - 1);
      pt->namelen = 0;
    }

  return pt;
}