gnupg/util/assuan-buffer.c

/* assuan-buffer.c - read and send data
 *	Copyright (C) 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
 *
 * This file is part of Assuan.
 *
 * Assuan is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * Assuan 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program; if not, see <http://www.gnu.org/licenses/>.
 */

/* Please note that this is a stripped down and modified version of
   the orginal Assuan code from libassuan. */


#include <config.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <errno.h>
#include <unistd.h>
#include <assert.h>
#ifdef HAVE_W32_SYSTEM
#include <process.h>
#endif
#include "assuan-defs.h"

#ifndef HAVE_MEMRCHR
void *memrchr(const void *s, int c, size_t n);
#endif

static int
writen (assuan_context_t ctx, const char *buffer, size_t length)
{
  while (length)
    {
      ssize_t nwritten = ctx->io->writefnc (ctx, buffer, length);
      
      if (nwritten < 0)
        {
          if (errno == EINTR)
            continue;
          return -1; /* write error */
        }
      length -= nwritten;
      buffer += nwritten;
    }
  return 0;  /* okay */
}

/* Read an entire line.  */
static int
readaline (assuan_context_t ctx, char *buf, size_t buflen,
	  int *r_nread, int *r_eof)
{
  size_t nleft = buflen;
  char *p;

  *r_eof = 0;
  *r_nread = 0;
  while (nleft > 0)
    {
      ssize_t n = ctx->io->readfnc (ctx, buf, nleft);

      if (n < 0)
        {
          if (errno == EINTR)
            continue;
          return -1; /* read error */
        }
      else if (!n)
        {
          *r_eof = 1;
          break; /* allow incomplete lines */
        }
      p = buf;
      nleft -= n;
      buf += n;
      *r_nread += n;

      p = memrchr (p, '\n', n);
      if (p)
        break; /* at least one full line available - that's enough for now */
    }

  return 0;
}


int
_assuan_read_line (assuan_context_t ctx)
{
  char *line = ctx->inbound.line;
  int nread, atticlen;
  int rc;
  char *endp = 0;

  if (ctx->inbound.eof)
    return -1;

  atticlen = ctx->inbound.attic.linelen;
  if (atticlen)
    {
      memcpy (line, ctx->inbound.attic.line, atticlen);
      ctx->inbound.attic.linelen = 0;

      endp = memchr (line, '\n', atticlen);
      if (endp)
	/* Found another line in the attic.  */
	{
	  rc = 0;
	  nread = atticlen;
	  atticlen = 0;
	}
      else
	/* There is pending data but not a full line.  */
        {
          assert (atticlen < LINELENGTH);
          rc = readaline (ctx, line + atticlen,
			 LINELENGTH - atticlen, &nread, &ctx->inbound.eof);
        }
    }
  else
    /* No pending data.  */
    rc = readaline (ctx, line, LINELENGTH,
                   &nread, &ctx->inbound.eof);
  if (rc)
    {
      if (ctx->log_fp)
	fprintf (ctx->log_fp, "%s[%u.%p] DBG: <- [Error: %s]\n",
		 assuan_get_assuan_log_prefix (),
                 (unsigned int)getpid (), (void *)ctx, strerror (errno));
      return ASSUAN_Read_Error;
    }
  if (!nread)
    {
      assert (ctx->inbound.eof);
      if (ctx->log_fp)
	fprintf (ctx->log_fp, "%s[%u.%p] DBG: <- [EOF]\n",
		 assuan_get_assuan_log_prefix (),
                 (unsigned int)getpid (), (void *)ctx);
      return -1;
    }

  ctx->inbound.attic.pending = 0;
  nread += atticlen;

  if (! endp)
    endp = memchr (line, '\n', nread);

  if (endp)
    {
      int n = endp - line + 1;
      if (n < nread)
	/* LINE contains more than one line.  We copy it to the attic
	   now as handlers are allowed to modify the passed
	   buffer.  */
	{
	  int len = nread - n;
	  memcpy (ctx->inbound.attic.line, endp + 1, len);
	  ctx->inbound.attic.pending = memrchr (endp + 1, '\n', len) ? 1 : 0;
	  ctx->inbound.attic.linelen = len;
	}

      if (endp != line && endp[-1] == '\r')
	endp --;
      *endp = 0;

      ctx->inbound.linelen = endp - line;
      if (ctx->log_fp)
	{
	  fprintf (ctx->log_fp, "%s[%u.%p] DBG: <- ",
		   assuan_get_assuan_log_prefix (),
                   (unsigned int)getpid (), (void *)ctx);
	  if (ctx->confidential)
	    fputs ("[Confidential data not shown]", ctx->log_fp);
	  else
	    _assuan_log_print_buffer (ctx->log_fp,
				      ctx->inbound.line,
				      ctx->inbound.linelen);
	  putc ('\n', ctx->log_fp);
	}
      return 0;
    }
  else
    {
      if (ctx->log_fp)
	fprintf (ctx->log_fp, "%s[%u.%p] DBG: <- [Invalid line]\n",
		 assuan_get_assuan_log_prefix (),
                 (unsigned int)getpid (), (void *)ctx);
      *line = 0;
      ctx->inbound.linelen = 0;
      return ctx->inbound.eof ? ASSUAN_Line_Not_Terminated
	: ASSUAN_Line_Too_Long;
    }
}


/* Read the next line from the client or server and return a pointer
   in *LINE to a buffer holding the line.  LINELEN is the length of
   *LINE.  The buffer is valid until the next read operation on it.
   The caller may modify the buffer.  The buffer is invalid (i.e. must
   not be used) if an error is returned.

   Returns 0 on success or an assuan error code.
   See also: assuan_pending_line().
*/
assuan_error_t
assuan_read_line (assuan_context_t ctx, char **line, size_t *linelen)
{
  assuan_error_t err;

  if (!ctx)
    return ASSUAN_Invalid_Value;

  err = _assuan_read_line (ctx);
  *line = ctx->inbound.line;
  *linelen = ctx->inbound.linelen;
  return err;
}


/* Return true if a full line is buffered (i.e. an entire line may be
   read without any I/O).  */
int
assuan_pending_line (assuan_context_t ctx)
{
  return ctx && ctx->inbound.attic.pending;
}


assuan_error_t 
_assuan_write_line (assuan_context_t ctx, const char *prefix,
                    const char *line, size_t len)
{
  int rc = 0;
  size_t prefixlen = prefix? strlen (prefix):0;

  /* Make sure that the line is short enough. */
  if (len + prefixlen + 2 > ASSUAN_LINELENGTH)
    {
      if (ctx->log_fp)
        fprintf (ctx->log_fp, "%s[%u.%p] DBG: -> "
                 "[supplied line too long -truncated]\n",
                 assuan_get_assuan_log_prefix (),
                 (unsigned int)getpid (), (void *)ctx);
      if (prefixlen > 5)
        prefixlen = 5;
      if (len > ASSUAN_LINELENGTH - prefixlen - 2)
        len = ASSUAN_LINELENGTH - prefixlen - 2 - 1;
    }

  /* Fixme: we should do some kind of line buffering.  */
  if (ctx->log_fp)
    {
      fprintf (ctx->log_fp, "%s[%u.%p] DBG: -> ",
	       assuan_get_assuan_log_prefix (),
               (unsigned int)getpid (), (void *)ctx);
      if (ctx->confidential)
	fputs ("[Confidential data not shown]", ctx->log_fp);
      else
	_assuan_log_print_buffer (ctx->log_fp, line, len);
      putc ('\n', ctx->log_fp);
    }

  if (prefixlen)
    {
      rc = writen (ctx, prefix, prefixlen);
      if (rc)
        rc = ASSUAN_Write_Error;
    }
  if (!rc)
    {
      rc = writen (ctx, line, len);
      if (rc)
        rc = ASSUAN_Write_Error;
      if (!rc)
        {
          rc = writen (ctx, "\n", 1);
          if (rc)
            rc = ASSUAN_Write_Error;
        }
    }
  return rc;
}


assuan_error_t 
assuan_write_line (assuan_context_t ctx, const char *line)
{
  size_t len;
  const char *s;

  if (!ctx)
    return ASSUAN_Invalid_Value;

  /* Make sure that we never take a LF from the user - this might
     violate the protocol. */
  s = strchr (line, '\n');
  len = s? (s-line) : strlen (line);

  if (ctx->log_fp && s)
    fprintf (ctx->log_fp, "%s[%u.%p] DBG: -> "
             "[supplied line contained a LF -truncated]\n",
             assuan_get_assuan_log_prefix (),
             (unsigned int)getpid (), (void *)ctx);

  return _assuan_write_line (ctx, NULL, line, len);
}



/* Write out the data in buffer as datalines with line wrapping and
   percent escaping.  This function is used for GNU's custom streams */
int
_assuan_cookie_write_data (void *cookie, const char *buffer, size_t orig_size)
{
  assuan_context_t ctx = cookie;
  size_t size = orig_size;
  char *line;
  size_t linelen;

  if (ctx->outbound.data.error)
    return 0;

  line = ctx->outbound.data.line;
  linelen = ctx->outbound.data.linelen;
  line += linelen;
  while (size)
    {
      /* insert data line header */
      if (!linelen)
        {
          *line++ = 'D';
          *line++ = ' ';
          linelen += 2;
        }
      
      /* copy data, keep some space for the CRLF and to escape one character */
      while (size && linelen < LINELENGTH-2-2)
        {
          if (*buffer == '%' || *buffer == '\r' || *buffer == '\n')
            {
              sprintf (line, "%%%02X", *(unsigned char*)buffer);
              line += 3;
              linelen += 3;
              buffer++;
            }
          else
            {
              *line++ = *buffer++;
              linelen++;
            }
          size--;
        }
      
      if (linelen >= LINELENGTH-2-2)
        {
          if (ctx->log_fp)
            {
	      fprintf (ctx->log_fp, "%s[%u.%p] DBG: -> ",
		       assuan_get_assuan_log_prefix (),
                       (unsigned int)getpid (), (void *)ctx);

              if (ctx->confidential)
                fputs ("[Confidential data not shown]", ctx->log_fp);
              else 
                _assuan_log_print_buffer (ctx->log_fp, 
                                          ctx->outbound.data.line,
                                          linelen);
              putc ('\n', ctx->log_fp);
            }
          *line++ = '\n';
          linelen++;
          if (writen (ctx, ctx->outbound.data.line, linelen))
            {
              ctx->outbound.data.error = ASSUAN_Write_Error;
              return 0;
            }
          line = ctx->outbound.data.line;
          linelen = 0;
        }
    }

  ctx->outbound.data.linelen = linelen;
  return (int)orig_size;
}


/* Write out any buffered data 
   This function is used for GNU's custom streams */
int
_assuan_cookie_write_flush (void *cookie)
{
  assuan_context_t ctx = cookie;
  char *line;
  size_t linelen;

  if (ctx->outbound.data.error)
    return 0;

  line = ctx->outbound.data.line;
  linelen = ctx->outbound.data.linelen;
  line += linelen;
  if (linelen)
    {
      if (ctx->log_fp)
	{
	  fprintf (ctx->log_fp, "%s[%u.%p] DBG: -> ",
		   assuan_get_assuan_log_prefix (),
                   (unsigned int)getpid (), (void *)ctx);
	  if (ctx->confidential)
	    fputs ("[Confidential data not shown]", ctx->log_fp);
	  else
	    _assuan_log_print_buffer (ctx->log_fp,
				      ctx->outbound.data.line, linelen);
	  putc ('\n', ctx->log_fp);
	}
      *line++ = '\n';
      linelen++;
      if (writen (ctx, ctx->outbound.data.line, linelen))
        {
          ctx->outbound.data.error = ASSUAN_Write_Error;
          return 0;
        }
      ctx->outbound.data.linelen = 0;
    }
  return 0;
}


/**
 * assuan_send_data:
 * @ctx: An assuan context
 * @buffer: Data to send or NULL to flush
 * @length: length of the data to send/
 * 
 * This function may be used by the server or the client to send data
 * lines.  The data will be escaped as required by the Assuan protocol
 * and may get buffered until a line is full.  To force sending the
 * data out @buffer may be passed as NULL (in which case @length must
 * also be 0); however when used by a client this flush operation does
 * also send the terminating "END" command to terminate the reponse on
 * a INQUIRE response.  However, when assuan_transact() is used, this
 * function takes care of sending END itself.
 * 
 * Return value: 0 on success or an error code
 **/

assuan_error_t
assuan_send_data (assuan_context_t ctx, const void *buffer, size_t length)
{
  if (!ctx)
    return ASSUAN_Invalid_Value;
  if (!buffer && length)
    return ASSUAN_Invalid_Value;

  if (!buffer)
    { /* flush what we have */
      _assuan_cookie_write_flush (ctx);
      if (ctx->outbound.data.error)
        return ctx->outbound.data.error;
      if (!ctx->is_server)
        return assuan_write_line (ctx, "END");
    }
  else
    {
      _assuan_cookie_write_data (ctx, buffer, length);
      if (ctx->outbound.data.error)
        return ctx->outbound.data.error;
    }

  return 0;
}