path: root/backend/net.c

/* sane - Scanner Access Now Easy.
   Copyright (C) 1997 David Mosberger-Tang
   Copyright (C) 2003, 2008 Julien BLACHE <jb@jblache.org>
      AF-independent code + IPv6, Avahi support

   This file is part of the SANE package.

   This program 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 2 of the
   License, or (at your option) any later version.

   This program 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/>.

   As a special exception, the authors of SANE give permission for
   additional uses of the libraries contained in this release of SANE.

   The exception is that, if you link a SANE library with other files
   to produce an executable, this does not by itself cause the
   resulting executable to be covered by the GNU General Public
   License.  Your use of that executable is in no way restricted on
   account of linking the SANE library code into it.

   This exception does not, however, invalidate any other reasons why
   the executable file might be covered by the GNU General Public
   License.

   If you submit changes to SANE to the maintainers to be included in
   a subsequent release, you agree by submitting the changes that
   those changes may be distributed with this exception intact.

   If you write modifications of your own for SANE, it is your choice
   whether to permit this exception to apply to your modifications.
   If you do not wish that, delete this exception notice.

   This file implements a SANE network-based meta backend.  */

#ifdef _AIX
# include "../include/lalloca.h" /* MUST come first for AIX! */
#endif

#include "../include/sane/config.h"
#include "../include/lalloca.h"
#include "../include/_stdint.h"

#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <pwd.h>
#ifdef HAVE_LIBC_H
# include <libc.h> /* NeXTStep/OpenStep */
#endif

#include <sys/time.h>
#include <sys/types.h>

#include <netinet/in.h>
#include <netdb.h> /* OS/2 needs this _after_ <netinet/in.h>, grrr... */

#if WITH_AVAHI
# include <avahi-client/client.h>
# include <avahi-client/lookup.h>

# include <avahi-common/thread-watch.h>
# include <avahi-common/malloc.h>
# include <avahi-common/error.h>

# define SANED_SERVICE_DNS "_sane-port._tcp"

static AvahiClient *avahi_client = NULL;
static AvahiThreadedPoll *avahi_thread = NULL;
static AvahiServiceBrowser *avahi_browser = NULL;
#endif /* WITH_AVAHI */

#include "../include/sane/sane.h"
#include "../include/sane/sanei.h"
#include "../include/sane/sanei_net.h"
#include "../include/sane/sanei_codec_bin.h"
#include "net.h"

#define BACKEND_NAME    net
#include "../include/sane/sanei_backend.h"

#ifndef PATH_MAX
# define PATH_MAX       1024
#endif

#include "../include/sane/sanei_config.h"
#define NET_CONFIG_FILE "net.conf"

/* Please increase version number with every change
   (don't forget to update net.desc) */

/* define the version string depending on which network code is used */
#if defined (HAVE_GETADDRINFO) && defined (HAVE_GETNAMEINFO)
# define NET_USES_AF_INDEP
# ifdef ENABLE_IPV6
#  define NET_VERSION "1.0.14 (AF-indep+IPv6)"
# else
#  define NET_VERSION "1.0.14 (AF-indep)"
# endif /* ENABLE_IPV6 */
#else
# undef ENABLE_IPV6
# define NET_VERSION "1.0.14"
#endif /* HAVE_GETADDRINFO && HAVE_GETNAMEINFO */

static SANE_Auth_Callback auth_callback;
static Net_Device *first_device;
static Net_Scanner *first_handle;
static const SANE_Device **devlist;
static int client_big_endian; /* 1 == big endian; 0 == little endian */
static int server_big_endian; /* 1 == big endian; 0 == little endian */
static int depth; /* bits per pixel */
static int connect_timeout = -1; /* timeout for connection to saned */

#ifndef NET_USES_AF_INDEP
static int saned_port;
#endif /* !NET_USES_AF_INDEP */

/* This variable is only needed, if the depth is 16bit/channel and
   client/server have different endianness.  A value of -1 means, that there's
   no hang over; otherwise the value has to be casted to SANE_Byte.  hang_over
   means, that there is a remaining byte from a previous call to sane_read,
   which could not be byte-swapped, e.g. because the frontend requested an odd
   number of bytes.
*/
static int hang_over;

/* This variable is only needed, if the depth is 16bit/channel and
   client/server have different endianness.  A value of -1 means, that there's
   no left over; otherwise the value has to be casted to SANE_Byte.  left_over
   means, that there is a remaining byte from a previous call to sane_read,
   which already is in the correct byte order, but could not be returned,
   e.g.  because the frontend requested only one byte per call.
*/
static int left_over;


#ifdef NET_USES_AF_INDEP
static SANE_Status
add_device (const char *name, Net_Device ** ndp)
{
  struct addrinfo hints;
  struct addrinfo *res;
  struct addrinfo *resp;
  struct sockaddr_in *sin;
#ifdef ENABLE_IPV6
  struct sockaddr_in6 *sin6;
#endif /* ENABLE_IPV6 */

  Net_Device *nd = NULL;

  int error;
  short sane_port = htons (6566);

  DBG (1, "add_device: adding backend %s\n", name);

  for (nd = first_device; nd; nd = nd->next)
    if (strcmp (nd->name, name) == 0)
      {
	DBG (1, "add_device: already in list\n");

	if (ndp)
	  *ndp = nd;

	return SANE_STATUS_GOOD;
      }

  memset (&hints, 0, sizeof(hints));

# ifdef ENABLE_IPV6
  hints.ai_family = PF_UNSPEC;
# else
  hints.ai_family = PF_INET;
# endif /* ENABLE_IPV6 */

  error = getaddrinfo (name, "sane-port", &hints, &res);
  if (error)
    {
      error = getaddrinfo (name, NULL, &hints, &res);
      if (error)
	{
	  DBG (1, "add_device: error while getting address of host %s: %s\n",
	       name, gai_strerror (error));

	  return SANE_STATUS_IO_ERROR;
	}
      else
	{
          for (resp = res; resp != NULL; resp = resp->ai_next)
            {
              switch (resp->ai_family)
                {
                  case AF_INET:
                    sin = (struct sockaddr_in *) resp->ai_addr;
                    sin->sin_port = sane_port;
                    break;
#ifdef ENABLE_IPV6
		  case AF_INET6:
		    sin6 = (struct sockaddr_in6 *) resp->ai_addr;
		    sin6->sin6_port = sane_port;
		    break;
#endif /* ENABLE_IPV6 */
                }
	    }
	}
    }

  nd = malloc (sizeof (Net_Device));
  if (!nd)
    {
      DBG (1, "add_device: not enough memory for Net_Device struct\n");

      freeaddrinfo (res);
      return SANE_STATUS_NO_MEM;
    }

  memset (nd, 0, sizeof (Net_Device));
  nd->name = strdup (name);
  if (!nd->name)
    {
      DBG (1, "add_device: not enough memory to duplicate name\n");
      free(nd);
      return SANE_STATUS_NO_MEM;
    }

  nd->addr = res;
  nd->ctl = -1;

  nd->next = first_device;

  first_device = nd;

  if (ndp)
    *ndp = nd;
  DBG (2, "add_device: backend %s added\n", name);
  return SANE_STATUS_GOOD;
}

#else /* !NET_USES_AF_INDEP */

static SANE_Status
add_device (const char *name, Net_Device ** ndp)
{
  struct hostent *he;
  Net_Device *nd;
  struct sockaddr_in *sin;

  DBG (1, "add_device: adding backend %s\n", name);

  for (nd = first_device; nd; nd = nd->next)
    if (strcmp (nd->name, name) == 0)
      {
	DBG (1, "add_device: already in list\n");

	if (ndp)
	  *ndp = nd;

	return SANE_STATUS_GOOD;
      }

  he = gethostbyname (name);
  if (!he)
    {
      DBG (1, "add_device: can't get address of host %s\n", name);
      return SANE_STATUS_IO_ERROR;
    }

  if (he->h_addrtype != AF_INET)
    {
      DBG (1, "add_device: don't know how to deal with addr family %d\n",
	   he->h_addrtype);
      return SANE_STATUS_INVAL;
    }

  nd = malloc (sizeof (*nd));
  if (!nd)
    {
      DBG (1, "add_device: not enough memory for Net_Device struct\n");
      return SANE_STATUS_NO_MEM;
    }

  memset (nd, 0, sizeof (*nd));
  nd->name = strdup (name);
  if (!nd->name)
    {
      DBG (1, "add_device: not enough memory to duplicate name\n");
      free (nd);
      return SANE_STATUS_NO_MEM;
    }
  nd->addr.sa_family = he->h_addrtype;

  sin = (struct sockaddr_in *) &nd->addr;
  memcpy (&sin->sin_addr, he->h_addr_list[0], he->h_length);

  nd->ctl = -1;
  nd->next = first_device;
  first_device = nd;
  if (ndp)
    *ndp = nd;
  DBG (2, "add_device: backend %s added\n", name);
  return SANE_STATUS_GOOD;
}
#endif /* NET_USES_AF_INDEP */

/* Calls getpwuid_r(). The return value must be freed by the caller. */
char* get_current_username()
{
  long bufsize = sysconf(_SC_GETPW_R_SIZE_MAX);
  if (bufsize == -1)
  {
    return NULL;
  }

  char* buf = (char*) malloc(bufsize);
  if (buf == NULL)
  {
    return NULL;
  }

  struct passwd pwd;
  struct passwd *result;
  if (getpwuid_r(getuid(), &pwd, buf, bufsize, &result) != 0 || result == NULL)
  {
    return NULL;
  }

  /* pw_name is allocated somewhere within buf, so we use memmove() */
  memmove(buf, pwd.pw_name, strlen(pwd.pw_name));
  return buf;
}

#ifdef NET_USES_AF_INDEP
static SANE_Status
connect_dev (Net_Device * dev)
{
  struct addrinfo *addrp;

  SANE_Word version_code;
  SANE_Init_Reply reply;
  SANE_Status status = SANE_STATUS_IO_ERROR;
  SANE_Init_Req req;
  SANE_Bool connected = SANE_FALSE;
#ifdef TCP_NODELAY
  int on = 1;
  int level = -1;
#endif
  struct timeval tv;

  int i;

  DBG (2, "connect_dev: trying to connect to %s\n", dev->name);

  for (addrp = dev->addr, i = 0; (addrp != NULL) && (connected == SANE_FALSE); addrp = addrp->ai_next, i++)
    {
# ifdef ENABLE_IPV6
      if ((addrp->ai_family != AF_INET) && (addrp->ai_family != AF_INET6))
# else /* !ENABLE_IPV6 */
      if (addrp->ai_family != AF_INET)
# endif /* ENABLE_IPV6 */
	{
	  DBG (1, "connect_dev: [%d] don't know how to deal with addr family %d\n",
	       i, addrp->ai_family);
	  continue;
	}

      dev->ctl = socket (addrp->ai_family, SOCK_STREAM, 0);
      if (dev->ctl < 0)
	{
	  DBG (1, "connect_dev: [%d] failed to obtain socket (%s)\n",
	       i, strerror (errno));
	  dev->ctl = -1;
	  continue;
	}

      /* Set SO_SNDTIMEO for the connection to saned */
      if (connect_timeout > 0)
	{
	  tv.tv_sec = connect_timeout;
	  tv.tv_usec = 0;

	  if (setsockopt (dev->ctl, SOL_SOCKET, SO_SNDTIMEO, &tv, sizeof(tv)) < 0)
	    {
	      DBG (1, "connect_dev: [%d] failed to set SO_SNDTIMEO (%s)\n", i, strerror (errno));
	    }
	}

      if (connect (dev->ctl, addrp->ai_addr, addrp->ai_addrlen) < 0)
	{
	  DBG (1, "connect_dev: [%d] failed to connect (%s)\n", i, strerror (errno));
	  dev->ctl = -1;
	  continue;
	}
      DBG (3, "connect_dev: [%d] connection succeeded (%s)\n", i, (addrp->ai_family == AF_INET6) ? "IPv6" : "IPv4");
      dev->addr_used = addrp;
      connected = SANE_TRUE;
    }

  if (connected != SANE_TRUE)
    {
      DBG (1, "connect_dev: couldn't connect to host (see messages above)\n");
      return SANE_STATUS_IO_ERROR;
    }

#else /* !NET_USES_AF_INDEP */

static SANE_Status
connect_dev (Net_Device * dev)
{
  struct sockaddr_in *sin;
  SANE_Word version_code;
  SANE_Init_Reply reply;
  SANE_Status status = SANE_STATUS_IO_ERROR;
  SANE_Init_Req req;
#ifdef TCP_NODELAY
  int on = 1;
  int level = -1;
#endif
  struct timeval tv;

  DBG (2, "connect_dev: trying to connect to %s\n", dev->name);

  if (dev->addr.sa_family != AF_INET)
    {
      DBG (1, "connect_dev: don't know how to deal with addr family %d\n",
	   dev->addr.sa_family);
      return SANE_STATUS_IO_ERROR;
    }

  dev->ctl = socket (dev->addr.sa_family, SOCK_STREAM, 0);
  if (dev->ctl < 0)
    {
      DBG (1, "connect_dev: failed to obtain socket (%s)\n",
	   strerror (errno));
      dev->ctl = -1;
      return SANE_STATUS_IO_ERROR;
    }
  sin = (struct sockaddr_in *) &dev->addr;
  sin->sin_port = saned_port;


  /* Set SO_SNDTIMEO for the connection to saned */
  if (connect_timeout > 0)
    {
      tv.tv_sec = connect_timeout;
      tv.tv_usec = 0;

      if (setsockopt (dev->ctl, SOL_SOCKET, SO_SNDTIMEO, &tv, sizeof(tv)) < 0)
	{
	  DBG (1, "connect_dev: failed to set SO_SNDTIMEO (%s)\n", strerror (errno));
	}
    }

  if (connect (dev->ctl, &dev->addr, sizeof (dev->addr)) < 0)
    {
      DBG (1, "connect_dev: failed to connect (%s)\n", strerror (errno));
      dev->ctl = -1;
      return SANE_STATUS_IO_ERROR;
    }
  DBG (3, "connect_dev: connection succeeded\n");
#endif /* NET_USES_AF_INDEP */

  /* We're connected now, so reset SO_SNDTIMEO to the default value of 0 */
  if (connect_timeout > 0)
    {
      tv.tv_sec = 0;
      tv.tv_usec = 0;

      if (setsockopt (dev->ctl, SOL_SOCKET, SO_SNDTIMEO, &tv, sizeof(tv)) < 0)
	{
	  DBG (1, "connect_dev: failed to reset SO_SNDTIMEO (%s)\n", strerror (errno));
	}
    }

#ifdef TCP_NODELAY
# ifdef SOL_TCP
  level = SOL_TCP;
# else /* !SOL_TCP */
  /* Look up the protocol level in the protocols database. */
  {
    struct protoent *p;
    p = getprotobyname ("tcp");
    if (p == 0)
      DBG (1, "connect_dev: cannot look up `tcp' protocol number");
    else
      level = p->p_proto;
  }
# endif	/* SOL_TCP */

  if (level == -1 ||
      setsockopt (dev->ctl, level, TCP_NODELAY, &on, sizeof (on)))
    DBG (1, "connect_dev: failed to put send socket in TCP_NODELAY mode (%s)",
	 strerror (errno));
#endif /* !TCP_NODELAY */

  DBG (2, "connect_dev: sanei_w_init\n");
  sanei_w_init (&dev->wire, sanei_codec_bin_init);
  dev->wire.io.fd = dev->ctl;
  dev->wire.io.read = read;
  dev->wire.io.write = write;

  /* exchange version codes with the server: */
  req.version_code = SANE_VERSION_CODE (V_MAJOR, V_MINOR,
					SANEI_NET_PROTOCOL_VERSION);
  req.username = get_current_username();
  DBG (2, "connect_dev: net_init (user=%s, local version=%d.%d.%d)\n",
       req.username, V_MAJOR, V_MINOR, SANEI_NET_PROTOCOL_VERSION);
  sanei_w_call (&dev->wire, SANE_NET_INIT,
		(WireCodecFunc) sanei_w_init_req, &req,
		(WireCodecFunc) sanei_w_init_reply, &reply);
  free(req.username);
  req.username = NULL;

  if (dev->wire.status != 0)
    {
      DBG (1, "connect_dev: argument marshalling error (%s)\n",
	   strerror (dev->wire.status));
      status = SANE_STATUS_IO_ERROR;
      goto fail;
    }

  status = reply.status;
  version_code = reply.version_code;
  DBG (2, "connect_dev: freeing init reply (status=%s, remote "
       "version=%d.%d.%d)\n", sane_strstatus (status),
       SANE_VERSION_MAJOR (version_code),
       SANE_VERSION_MINOR (version_code), SANE_VERSION_BUILD (version_code));
  sanei_w_free (&dev->wire, (WireCodecFunc) sanei_w_init_reply, &reply);

  if (status != 0)
    {
      DBG (1, "connect_dev: access to %s denied\n", dev->name);
      goto fail;
    }
  if (SANE_VERSION_MAJOR (version_code) != V_MAJOR)
    {
      DBG (1, "connect_dev: major version mismatch: got %d, expected %d\n",
	   SANE_VERSION_MAJOR (version_code), V_MAJOR);
      status = SANE_STATUS_IO_ERROR;
      goto fail;
    }
  if (SANE_VERSION_BUILD (version_code) != SANEI_NET_PROTOCOL_VERSION
      && SANE_VERSION_BUILD (version_code) != 2)
    {
      DBG (1, "connect_dev: network protocol version mismatch: "
	   "got %d, expected %d\n",
	   SANE_VERSION_BUILD (version_code), SANEI_NET_PROTOCOL_VERSION);
      status = SANE_STATUS_IO_ERROR;
      goto fail;
    }
  dev->wire.version = SANE_VERSION_BUILD (version_code);
  DBG (4, "connect_dev: done\n");
  return SANE_STATUS_GOOD;

fail:
  DBG (2, "connect_dev: closing connection to %s\n", dev->name);
  close (dev->ctl);
  dev->ctl = -1;
  return status;
}


static SANE_Status
fetch_options (Net_Scanner * s)
{
  int option_number;
  DBG (3, "fetch_options: %p\n", (void *) s);

  if (s->opt.num_options)
    {
      DBG (2, "fetch_options: %d option descriptors cached... freeing\n",
	   s->opt.num_options);
      sanei_w_set_dir (&s->hw->wire, WIRE_FREE);
      s->hw->wire.status = 0;
      sanei_w_option_descriptor_array (&s->hw->wire, &s->opt);
      if (s->hw->wire.status)
	{
	  DBG (1, "fetch_options: failed to free old list (%s)\n",
	       strerror (s->hw->wire.status));
	  return SANE_STATUS_IO_ERROR;
	}
    }
  DBG (3, "fetch_options: get_option_descriptors\n");
  sanei_w_call (&s->hw->wire, SANE_NET_GET_OPTION_DESCRIPTORS,
		(WireCodecFunc) sanei_w_word, &s->handle,
		(WireCodecFunc) sanei_w_option_descriptor_array, &s->opt);
  if (s->hw->wire.status)
    {
      DBG (1, "fetch_options: failed to get option descriptors (%s)\n",
	   strerror (s->hw->wire.status));
      return SANE_STATUS_IO_ERROR;
    }

  if (s->local_opt.num_options == 0)
    {
      DBG (3, "fetch_options: creating %d local option descriptors\n",
	   s->opt.num_options);
      s->local_opt.desc =
	malloc (s->opt.num_options * sizeof (s->local_opt.desc));
      if (!s->local_opt.desc)
	{
	  DBG (1, "fetch_options: couldn't malloc s->local_opt.desc\n");
	  return SANE_STATUS_NO_MEM;
	}
      for (option_number = 0;
	   option_number < s->opt.num_options;
	   option_number++)
	{
	  s->local_opt.desc[option_number] =
	    malloc (sizeof (SANE_Option_Descriptor));
	  if (!s->local_opt.desc[option_number])
	    {
	      DBG (1, "fetch_options: couldn't malloc "
		   "s->local_opt.desc[%d]\n", option_number);
	      return SANE_STATUS_NO_MEM;
	    }
	}
      s->local_opt.num_options = s->opt.num_options;
    }
  else if (s->local_opt.num_options != s->opt.num_options)
    {
      DBG (1, "fetch_options: option number count changed during runtime?\n");
      return SANE_STATUS_INVAL;
    }

  DBG (3, "fetch_options: copying %d option descriptors\n",
       s->opt.num_options);

  for (option_number = 0; option_number < s->opt.num_options; option_number++)
    {
      memcpy (s->local_opt.desc[option_number], s->opt.desc[option_number],
	      sizeof (SANE_Option_Descriptor));
    }

  s->options_valid = 1;
  DBG (3, "fetch_options: %d options fetched\n", s->opt.num_options);
  return SANE_STATUS_GOOD;
}

static SANE_Status
do_cancel (Net_Scanner * s)
{
  DBG (2, "do_cancel: %p\n", (void *) s);
  s->hw->auth_active = 0;
  if (s->data >= 0)
    {
      DBG (3, "do_cancel: closing data pipe\n");
      close (s->data);
      s->data = -1;
    }
  return SANE_STATUS_CANCELLED;
}

static void
do_authorization (Net_Device * dev, SANE_String resource)
{
  SANE_Authorization_Req req;
  SANE_Char username[SANE_MAX_USERNAME_LEN];
  SANE_Char password[SANE_MAX_PASSWORD_LEN];
  char *net_resource;

  DBG (2, "do_authorization: dev=%p resource=%s\n", (void *) dev, resource);

  dev->auth_active = 1;

  memset (&req, 0, sizeof (req));
  memset (username, 0, sizeof (SANE_Char) * SANE_MAX_USERNAME_LEN);
  memset (password, 0, sizeof (SANE_Char) * SANE_MAX_PASSWORD_LEN);

  net_resource = malloc (strlen (resource) + 6 + strlen (dev->name));

  if (net_resource != NULL)
    {
      sprintf (net_resource, "net:%s:%s", dev->name, resource);
      if (auth_callback)
	{
	  DBG (2, "do_authorization: invoking auth_callback, resource = %s\n",
	       net_resource);
	  (*auth_callback) (net_resource, username, password);
	}
      else
	DBG (1, "do_authorization: no auth_callback present\n");
      free (net_resource);
    }
  else /* Is this necessary? If we don't have these few bytes we will get
	  in trouble later anyway */
    {
      DBG (1, "do_authorization: not enough memory for net_resource\n");
      if (auth_callback)
	{
	  DBG (2, "do_authorization: invoking auth_callback, resource = %s\n",
	       resource);
	  (*auth_callback) (resource, username, password);
	}
      else
	DBG (1, "do_authorization: no auth_callback present\n");
    }

  if (dev->auth_active)
    {
      SANE_Word ack;

      req.resource = resource;
      req.username = username;
      req.password = password;
      DBG (2, "do_authorization: relaying authentication data\n");
      sanei_w_call (&dev->wire, SANE_NET_AUTHORIZE,
		    (WireCodecFunc) sanei_w_authorization_req, &req,
		    (WireCodecFunc) sanei_w_word, &ack);
    }
  else
    DBG (1, "do_authorization: auth_active is false... strange\n");
}


#if WITH_AVAHI
static void
net_avahi_resolve_callback (AvahiServiceResolver *r, AvahiIfIndex interface, AvahiProtocol protocol,
			    AvahiResolverEvent event, const char *name, const char *type,
			    const char *domain, const char *host_name, const AvahiAddress *address,
			    uint16_t port, AvahiStringList *txt, AvahiLookupResultFlags flags,
			    void *userdata)
{
  char a[AVAHI_ADDRESS_STR_MAX];
  char *t;

  /* unused */
  (void) interface;
  (void) protocol;
  (void) userdata;

  if (!r)
    return;

  switch (event)
    {
      case AVAHI_RESOLVER_FAILURE:
	DBG (1, "net_avahi_resolve_callback: failed to resolve service '%s' of type '%s' in domain '%s': %s\n",
	     name, type, domain, avahi_strerror (avahi_client_errno (avahi_service_resolver_get_client (r))));
	break;

      case AVAHI_RESOLVER_FOUND:
	DBG (3, "net_avahi_resolve_callback: service '%s' of type '%s' in domain '%s':\n", name, type, domain);

	avahi_address_snprint(a, sizeof (a), address);
	t = avahi_string_list_to_string (txt);

	DBG (3, "\t%s:%u (%s)\n\tTXT=%s\n\tcookie is %u\n\tis_local: %i\n\tour_own: %i\n"
	     "\twide_area: %i\n\tmulticast: %i\n\tcached: %i\n",
	     host_name, port, a, t, avahi_string_list_get_service_cookie (txt),
	     !!(flags & AVAHI_LOOKUP_RESULT_LOCAL), !!(flags & AVAHI_LOOKUP_RESULT_OUR_OWN),
	     !!(flags & AVAHI_LOOKUP_RESULT_WIDE_AREA), !!(flags & AVAHI_LOOKUP_RESULT_MULTICAST),
	     !!(flags & AVAHI_LOOKUP_RESULT_CACHED));

	/* TODO: evaluate TXT record */

	/* Try first with the name */
	if (add_device (host_name, NULL) != SANE_STATUS_GOOD)
	  {
	    DBG (1, "net_avahi_resolve_callback: couldn't add backend with name %s\n", host_name);

	    /* Then try the raw IP address */
	    if (add_device (t, NULL) != SANE_STATUS_GOOD)
	      DBG (1, "net_avahi_resolve_callback: couldn't add backend with IP address %s either\n", t);
	  }

	avahi_free (t);
	break;
    }

  avahi_service_resolver_free(r);
}

static void
net_avahi_browse_callback (AvahiServiceBrowser *b, AvahiIfIndex interface, AvahiProtocol protocol,
			   AvahiBrowserEvent event, const char *name, const char *type,
			   const char *domain, AvahiLookupResultFlags flags, void *userdata)
{
  AvahiProtocol proto;

  /* unused */
  (void) flags;
  (void) userdata;

  if (!b)
    return;

  switch (event)
    {
      case AVAHI_BROWSER_FAILURE:
	DBG (1, "net_avahi_browse_callback: %s\n", avahi_strerror (avahi_client_errno (avahi_service_browser_get_client (b))));
	avahi_threaded_poll_quit (avahi_thread);
	return;

      case AVAHI_BROWSER_NEW:
	DBG (3, "net_avahi_browse_callback: NEW: service '%s' of type '%s' in domain '%s'\n", name, type, domain);

	/* The server will actually be added to our list in the resolver callback */

	/* The resolver object will be freed in the resolver callback, or by
	 * the server if it terminates before the callback is called.
	 */
#ifdef ENABLE_IPV6
	proto = AVAHI_PROTO_UNSPEC;
#else
	proto = AVAHI_PROTO_INET;
#endif /* ENABLE_IPV6 */
	if (!(avahi_service_resolver_new (avahi_client, interface, protocol, name, type, domain, proto, 0, net_avahi_resolve_callback, NULL)))
	  DBG (2, "net_avahi_browse_callback: failed to resolve service '%s': %s\n", name, avahi_strerror (avahi_client_errno (avahi_client)));
	break;

      case AVAHI_BROWSER_REMOVE:
	DBG (3, "net_avahi_browse_callback: REMOVE: service '%s' of type '%s' in domain '%s'\n", name, type, domain);
	/* With the current architecture, we cannot safely remove a server from the list */
	break;

      case AVAHI_BROWSER_ALL_FOR_NOW:
      case AVAHI_BROWSER_CACHE_EXHAUSTED:
	DBG (3, "net_avahi_browse_callback: %s\n", event == AVAHI_BROWSER_CACHE_EXHAUSTED ? "CACHE_EXHAUSTED" : "ALL_FOR_NOW");
	break;
    }
}

static void
net_avahi_callback (AvahiClient *c, AvahiClientState state, void * userdata)
{
  AvahiProtocol proto;
  int error;

  /* unused */
  (void) userdata;

  if (!c)
    return;

  switch (state)
    {
      case AVAHI_CLIENT_CONNECTING:
	break;

      case AVAHI_CLIENT_S_COLLISION:
      case AVAHI_CLIENT_S_REGISTERING:
      case AVAHI_CLIENT_S_RUNNING:
	if (avahi_browser)
	  return;

#ifdef ENABLE_IPV6
	proto = AVAHI_PROTO_UNSPEC;
#else
	proto = AVAHI_PROTO_INET;
#endif /* ENABLE_IPV6 */

	avahi_browser = avahi_service_browser_new (c, AVAHI_IF_UNSPEC, proto, SANED_SERVICE_DNS, NULL, 0, net_avahi_browse_callback, NULL);
	if (avahi_browser == NULL)
	  {
	    DBG (1, "net_avahi_callback: could not create service browser: %s\n", avahi_strerror (avahi_client_errno (c)));
	    avahi_threaded_poll_quit (avahi_thread);
	  }
	break;

      case AVAHI_CLIENT_FAILURE:
	error = avahi_client_errno (c);

	if (error == AVAHI_ERR_DISCONNECTED)
	  {
	    /* Server disappeared - try to reconnect */
	    if (avahi_browser)
	      {
		avahi_service_browser_free (avahi_browser);
		avahi_browser = NULL;
	      }

	    avahi_client_free (avahi_client);
	    avahi_client = NULL;

	    avahi_client = avahi_client_new (avahi_threaded_poll_get (avahi_thread), AVAHI_CLIENT_NO_FAIL, net_avahi_callback, NULL, &error);
	    if (avahi_client == NULL)
	      {
		DBG (1, "net_avahi_init: could not create Avahi client: %s\n", avahi_strerror (error));
		avahi_threaded_poll_quit (avahi_thread);
	      }
	  }
	else
	  {
	    /* Another error happened - game over */
	    DBG (1, "net_avahi_callback: server connection failure: %s\n", avahi_strerror (error));
	    avahi_threaded_poll_quit (avahi_thread);
	  }
	break;
    }
}


static void
net_avahi_init (void)
{
  int error;

  avahi_thread = avahi_threaded_poll_new ();
  if (avahi_thread == NULL)
    {
      DBG (1, "net_avahi_init: could not create threaded poll object\n");
      goto fail;
    }

  avahi_client = avahi_client_new (avahi_threaded_poll_get (avahi_thread), AVAHI_CLIENT_NO_FAIL, net_avahi_callback, NULL, &error);
  if (avahi_client == NULL)
    {
      DBG (1, "net_avahi_init: could not create Avahi client: %s\n", avahi_strerror (error));
      goto fail;
    }

  if (avahi_threaded_poll_start (avahi_thread) < 0)
    {
      DBG (1, "net_avahi_init: Avahi thread failed to start\n");
      goto fail;
    }

  /* All done */
  return;

 fail:
  DBG (1, "net_avahi_init: Avahi init failed, support disabled\n");

  if (avahi_client)
    {
      avahi_client_free (avahi_client);
      avahi_client = NULL;
    }

  if (avahi_thread)
    {
      avahi_threaded_poll_free (avahi_thread);
      avahi_thread = NULL;
    }
}

static void
net_avahi_cleanup (void)
{
  if (!avahi_thread)
    return;

  DBG (1, "net_avahi_cleanup: stopping thread\n");

  avahi_threaded_poll_stop (avahi_thread);

  if (avahi_browser)
    avahi_service_browser_free (avahi_browser);

  if (avahi_client)
    avahi_client_free (avahi_client);

  avahi_threaded_poll_free (avahi_thread);

  DBG (1, "net_avahi_cleanup: done\n");
}
#endif /* WITH_AVAHI */


SANE_Status
sane_init (SANE_Int * version_code, SANE_Auth_Callback authorize)
{
  char device_name[PATH_MAX];
  const char *optval;
  const char *env;
  size_t len;
  FILE *fp;
  short ns = 0x1234;
  unsigned char *p = (unsigned char *)(&ns);

#ifndef NET_USES_AF_INDEP
  struct servent *serv;
#endif /* !NET_USES_AF_INDEP */

  DBG_INIT ();

  DBG (2, "sane_init: authorize %s null, version_code %s null\n", (authorize) ? "!=" : "==",
       (version_code) ? "!=" : "==");

  devlist = NULL;
  first_device = NULL;
  first_handle = NULL;

#if WITH_AVAHI
  net_avahi_init ();
#endif /* WITH_AVAHI */

  auth_callback = authorize;

  /* Return the version number of the sane-backends package to allow
     the frontend to print them. This is done only for net and dll,
     because these backends are usually called by the frontend. */
  if (version_code)
    *version_code = SANE_VERSION_CODE (SANE_DLL_V_MAJOR, SANE_DLL_V_MINOR,
				       SANE_DLL_V_BUILD);

  DBG (1, "sane_init: SANE net backend version %s from %s\n", NET_VERSION,
       PACKAGE_STRING);

  /* determine (client) machine byte order */
  if (*p == 0x12)
    {
      client_big_endian = 1;
      DBG (3, "sane_init: Client has big endian byte order\n");
    }
  else
    {
      client_big_endian = 0;
      DBG (3, "sane_init: Client has little endian byte order\n");
    }

#ifndef NET_USES_AF_INDEP
  DBG (2, "sane_init: determining sane service port\n");
  serv = getservbyname ("sane-port", "tcp");

  if (serv)
    {
      DBG (2, "sane_init: found port %d\n", ntohs (serv->s_port));
      saned_port = serv->s_port;
    }
  else
    {
      saned_port = htons (6566);
      DBG (1, "sane_init: could not find `sane-port' service (%s); using default "
	   "port %d\n", strerror (errno), ntohs (saned_port));
    }
#endif /* !NET_USES_AF_INDEP */

  DBG (2, "sane_init: searching for config file\n");
  fp = sanei_config_open (NET_CONFIG_FILE);
  if (fp)
    {
      while (sanei_config_read (device_name, sizeof (device_name), fp))
	{
	  if (device_name[0] == '#')	/* ignore line comments */
	    continue;
	  len = strlen (device_name);

	  if (!len)
	    continue;		/* ignore empty lines */

	  /*
	   * Check for net backend options.
	   * Anything that isn't an option is a saned host.
	   */
	  if (strstr(device_name, "connect_timeout") != NULL)
	    {
	      /* Look for the = sign; if it's not there, error out */
	      optval = strchr(device_name, '=');

	      if (!optval)
		continue;

	      optval = sanei_config_skip_whitespace (++optval);
	      if ((optval != NULL) && (*optval != '\0'))
		{
		  connect_timeout = atoi(optval);

		  DBG (2, "sane_init: connect timeout set to %d seconds\n", connect_timeout);
		}

	      continue;
	    }
#if WITH_AVAHI
	  avahi_threaded_poll_lock (avahi_thread);
#endif /* WITH_AVAHI */
	  DBG (2, "sane_init: trying to add %s\n", device_name);
	  add_device (device_name, 0);
#if WITH_AVAHI
	  avahi_threaded_poll_unlock (avahi_thread);
#endif /* WITH_AVAHI */
	}

      fclose (fp);
      DBG (2, "sane_init: done reading config\n");
    }
  else
    DBG (1, "sane_init: could not open config file (%s): %s\n",
	 NET_CONFIG_FILE, strerror (errno));

  DBG (2, "sane_init: evaluating environment variable SANE_NET_HOSTS\n");
  env = getenv ("SANE_NET_HOSTS");
  if (env)
    {
      char *copy, *next, *host;
      if ((copy = strdup (env)) != NULL)
	{
	  next = copy;
	  while ((host = strsep (&next, ":")))
	    {
#ifdef ENABLE_IPV6
	      if (host[0] == '[')
		{
		  /* skip '[' (host[0]) */
		  host++;
		  /* get the rest of the IPv6 addr (we're screwed if ] is missing)
		   * Is it worth checking for the matching ] ? Not for now. */
		  strsep (&next, "]");
		  /* add back the ":" that got removed by the strsep() */
		  host[strlen (host)] = ':';
		  /* host now holds the IPv6 address */

		  /* skip the ':' that could be after ] (avoids a call to strsep() */
		  if (next[0] == ':')
		    next++;
		}

	      /*
	       * if the IPv6 is last in the list, the strsep() call in the while()
	       * will return a string with the first char being '\0'. Skip it.
	       */
	      if (host[0] == '\0')
		  continue;
#endif /* ENABLE_IPV6 */
#if WITH_AVAHI
	      avahi_threaded_poll_lock (avahi_thread);
#endif /* WITH_AVAHI */
	      DBG (2, "sane_init: trying to add %s\n", host);
	      add_device (host, 0);
#if WITH_AVAHI
	      avahi_threaded_poll_unlock (avahi_thread);
#endif /* WITH_AVAHI */
	    }
	  free (copy);
	}
      else
	DBG (1, "sane_init: not enough memory to duplicate "
	     "environment variable\n");
    }

  DBG (2, "sane_init: evaluating environment variable SANE_NET_TIMEOUT\n");
  env = getenv ("SANE_NET_TIMEOUT");
  if (env)
    {
      connect_timeout = atoi(env);
      DBG (2, "sane_init: connect timeout set to %d seconds from env\n", connect_timeout);
    }

  DBG (2, "sane_init: done\n");
  return SANE_STATUS_GOOD;
}

void
sane_exit (void)
{
  Net_Scanner *handle, *next_handle;
  Net_Device *dev, *next_device;
  int i;

  DBG (1, "sane_exit: exiting\n");

#if WITH_AVAHI
  net_avahi_cleanup ();
#endif /* WITH_AVAHI */

  /* first, close all handles: */
  for (handle = first_handle; handle; handle = next_handle)
    {
      next_handle = handle->next;
      sane_close (handle);
    }
  first_handle = 0;

  /* now close all devices: */
  for (dev = first_device; dev; dev = next_device)
    {
      next_device = dev->next;

      DBG (2, "sane_exit: closing dev %p, ctl=%d\n", (void *) dev, dev->ctl);

      if (dev->ctl >= 0)
	{
	  sanei_w_call (&dev->wire, SANE_NET_EXIT,
			(WireCodecFunc) sanei_w_void, 0,
			(WireCodecFunc) sanei_w_void, 0);
	  sanei_w_exit (&dev->wire);
	  close (dev->ctl);
	}
      if (dev->name)
	free ((void *) dev->name);

#ifdef NET_USES_AF_INDEP
      if (dev->addr)
	freeaddrinfo(dev->addr);
#endif /* NET_USES_AF_INDEP */

      free (dev);
    }
  if (devlist)
    {
      for (i = 0; devlist[i]; ++i)
	{
	  if (devlist[i]->vendor)
	    free ((void *) devlist[i]->vendor);
	  if (devlist[i]->model)
	    free ((void *) devlist[i]->model);
	  if (devlist[i]->type)
	    free ((void *) devlist[i]->type);
	  free ((void *) devlist[i]);
	}
      free (devlist);
    }
  DBG (3, "sane_exit: finished.\n");
}

/* Note that a call to get_devices() implies that we'll have to
   connect to all remote hosts.  To avoid this, you can call
   sane_open() directly (assuming you know the name of the
   backend/device).  This is appropriate for the command-line
   interface of SANE, for example.
 */
SANE_Status
sane_get_devices (const SANE_Device *** device_list, SANE_Bool local_only)
{
  static int devlist_size = 0, devlist_len = 0;
  static const SANE_Device *empty_devlist[1] = { 0 };
  SANE_Get_Devices_Reply reply;
  SANE_Status status;
  Net_Device *dev;
  char *full_name;
  int i, num_devs;
  size_t len;
#define ASSERT_SPACE(n) do                                                 \
  {                                                                        \
    if (devlist_len + (n) > devlist_size)                                  \
      {                                                                    \
        devlist_size += (n) + 15;                                          \
        if (devlist)                                                       \
          devlist = realloc (devlist, devlist_size * sizeof (devlist[0])); \
        else                                                               \
          devlist = malloc (devlist_size * sizeof (devlist[0]));           \
        if (!devlist)                                                      \
          {                                                                \
             DBG (1, "sane_get_devices: not enough memory\n");	           \
             return SANE_STATUS_NO_MEM;                                    \
          }                                                                \
      }                                                                    \
  } while (0)

  DBG (3, "sane_get_devices: local_only = %d\n", local_only);

  if (local_only)
    {
      *device_list = empty_devlist;
      return SANE_STATUS_GOOD;
    }

  if (devlist)
    {
      DBG (2, "sane_get_devices: freeing devlist\n");
      for (i = 0; devlist[i]; ++i)
	{
	  if (devlist[i]->vendor)
	    free ((void *) devlist[i]->vendor);
	  if (devlist[i]->model)
	    free ((void *) devlist[i]->model);
	  if (devlist[i]->type)
	    free ((void *) devlist[i]->type);
	  free ((void *) devlist[i]);
	}
      free (devlist);
      devlist = 0;
    }
  devlist_len = 0;
  devlist_size = 0;

  for (dev = first_device; dev; dev = dev->next)
    {
      if (dev->ctl < 0)
	{
	  status = connect_dev (dev);
	  if (status != SANE_STATUS_GOOD)
	    {
	      DBG (1, "sane_get_devices: ignoring failure to connect to %s\n",
		   dev->name);
	      continue;
	    }
	}
      sanei_w_call (&dev->wire, SANE_NET_GET_DEVICES,
		    (WireCodecFunc) sanei_w_void, 0,
		    (WireCodecFunc) sanei_w_get_devices_reply, &reply);
      if (reply.status != SANE_STATUS_GOOD)
	{
	  DBG (1, "sane_get_devices: ignoring rpc-returned status %s\n",
	       sane_strstatus (reply.status));
	  sanei_w_free (&dev->wire,
			(WireCodecFunc) sanei_w_get_devices_reply, &reply);
	  continue;
	}

      /* count the number of devices for this backend: */
      for (num_devs = 0; reply.device_list[num_devs]; ++num_devs);

      ASSERT_SPACE (num_devs);

      for (i = 0; i < num_devs; ++i)
	{
	  SANE_Device *rdev;
	  char *mem;
#ifdef ENABLE_IPV6
	  SANE_Bool IPv6 = SANE_FALSE;
#endif /* ENABLE_IPV6 */

	  /* create a new device entry with a device name that is the
	     sum of the backend name a colon and the backend's device
	     name: */
	  len = strlen (dev->name) + 1 + strlen (reply.device_list[i]->name);

#ifdef ENABLE_IPV6
	  if (strchr (dev->name, ':') != NULL)
	    {
	      len += 2;
	      IPv6 = SANE_TRUE;
	    }
#endif /* ENABLE_IPV6 */

	  mem = malloc (sizeof (*dev) + len + 1);
	  if (!mem)
	    {
	      DBG (1, "sane_get_devices: not enough free memory\n");
	      sanei_w_free (&dev->wire,
			    (WireCodecFunc) sanei_w_get_devices_reply,
			    &reply);
	      return SANE_STATUS_NO_MEM;
	    }

	  memset (mem, 0, sizeof (*dev) + len);
	  full_name = mem + sizeof (*dev);

#ifdef ENABLE_IPV6
	  if (IPv6 == SANE_TRUE)
	    strcat (full_name, "[");
#endif /* ENABLE_IPV6 */

	  strcat (full_name, dev->name);

#ifdef ENABLE_IPV6
	  if (IPv6 == SANE_TRUE)
	    strcat (full_name, "]");
#endif /* ENABLE_IPV6 */

	  strcat (full_name, ":");
	  strcat (full_name, reply.device_list[i]->name);
	  DBG (3, "sane_get_devices: got %s\n", full_name);

	  rdev = (SANE_Device *) mem;
	  rdev->name = full_name;
	  rdev->vendor = strdup (reply.device_list[i]->vendor);
	  rdev->model = strdup (reply.device_list[i]->model);
	  rdev->type = strdup (reply.device_list[i]->type);

	  if ((!rdev->vendor) || (!rdev->model) || (!rdev->type))
	    {
	      DBG (1, "sane_get_devices: not enough free memory\n");
	      if (rdev->vendor)
		free ((void *) rdev->vendor);
	      if (rdev->model)
		free ((void *) rdev->model);
	      if (rdev->type)
		free ((void *) rdev->type);
	      free (rdev);
	      sanei_w_free (&dev->wire,
			    (WireCodecFunc) sanei_w_get_devices_reply,
			    &reply);
	      return SANE_STATUS_NO_MEM;
	    }

	  devlist[devlist_len++] = rdev;
	}
      /* now free up the rpc return value: */
      sanei_w_free (&dev->wire,
		    (WireCodecFunc) sanei_w_get_devices_reply, &reply);
    }

  /* terminate device list with NULL entry: */
  ASSERT_SPACE (1);
  devlist[devlist_len++] = 0;

  *device_list = devlist;
  DBG (2, "sane_get_devices: finished (%d devices)\n", devlist_len - 1);
  return SANE_STATUS_GOOD;
}

SANE_Status
sane_open (SANE_String_Const full_name, SANE_Handle * meta_handle)
{
  SANE_Open_Reply reply;
  const char *dev_name;
#ifdef ENABLE_IPV6
  const char *tmp_name;
  SANE_Bool v6addr = SANE_FALSE;
#endif /* ENABLE_IPV6 */
  SANE_String nd_name;
  SANE_Status status;
  SANE_Word handle;
  SANE_Word ack;
  Net_Device *dev;
  Net_Scanner *s;
  int need_auth;

  DBG (3, "sane_open(\"%s\")\n", full_name);

#ifdef ENABLE_IPV6
  /*
   * Check whether a numerical IPv6 host was specified
   * [2001:42:42::12] <== check for '[' as full_name[0]
   * ex: [2001:42:42::12]:test:0 (syntax taken from Apache 2)
   */
  if (full_name[0] == '[')
    {
      v6addr = SANE_TRUE;
      tmp_name = strchr (full_name, ']');
      if (!tmp_name)
	{
	  DBG (1, "sane_open: incorrect host address: missing matching ']'\n");
	  return SANE_STATUS_INVAL;
	}
    }
  else
    tmp_name = full_name;

  dev_name = strchr (tmp_name, ':');
#else /* !ENABLE_IPV6 */

  dev_name = strchr (full_name, ':');
#endif /* ENABLE_IPV6 */

  if (dev_name)
    {
#ifdef strndupa
# ifdef ENABLE_IPV6
      if (v6addr == SANE_TRUE)
	nd_name = strndupa (full_name + 1, dev_name - full_name - 2);
      else
	nd_name = strndupa (full_name, dev_name - full_name);

# else /* !ENABLE_IPV6 */

      nd_name = strndupa (full_name, dev_name - full_name);
# endif /* ENABLE_IPV6 */

      if (!nd_name)
	{
	  DBG (1, "sane_open: not enough free memory\n");
	  return SANE_STATUS_NO_MEM;
	}
#else
      char *tmp;

# ifdef ENABLE_IPV6
      if (v6addr == SANE_TRUE)
	tmp = alloca (dev_name - full_name - 2 + 1);
      else
	tmp = alloca (dev_name - full_name + 1);

# else /* !ENABLE_IPV6 */

      tmp = alloca (dev_name - full_name + 1);
# endif /* ENABLE_IPV6 */

      if (!tmp)
	{
	  DBG (1, "sane_open: not enough free memory\n");
	  return SANE_STATUS_NO_MEM;
	}

# ifdef ENABLE_IPV6
      if (v6addr == SANE_TRUE)
	{
	  memcpy (tmp, full_name + 1, dev_name - full_name - 2);
	  tmp[dev_name - full_name - 2] = '\0';
	}
      else
	{
	  memcpy (tmp, full_name, dev_name - full_name);
	  tmp[dev_name - full_name] = '\0';
	}

# else /* !ENABLE_IPV6 */

      memcpy (tmp, full_name, dev_name - full_name);
      tmp[dev_name - full_name] = '\0';
# endif /* ENABLE_IPV6 */

      nd_name = tmp;
#endif
      ++dev_name;		/* skip colon */
    }
  else
    {
      /* if no colon interpret full_name as the host name; an empty
         device name will cause us to open the first device of that
         host.  */
#ifdef ENABLE_IPV6
      if (v6addr == SANE_TRUE)
	{
	  nd_name = alloca (strlen (full_name) - 2 + 1);
	  if (!nd_name)
	    {
	      DBG (1, "sane_open: not enough free memory\n");
	      return SANE_STATUS_NO_MEM;
	    }
	  memcpy (nd_name, full_name + 1, strlen (full_name) - 2);
	  nd_name[strlen (full_name) - 2] = '\0';
	}
      else
	nd_name = (char *) full_name;

#else /* !ENABLE_IPV6 */

      nd_name = (char *) full_name;
#endif /* ENABLE_IPV6 */

      dev_name = "";
    }
  DBG (2, "sane_open: host = %s, device = %s\n", nd_name, dev_name);

  if (!nd_name[0])
    {
      /* Unlike other backends, we never allow an empty backend-name.
         Otherwise, it's possible that sane_open("") will result in
         endless looping (consider the case where NET is the first
         backend...) */

      DBG (1, "sane_open: empty backend name is not allowed\n");
      return SANE_STATUS_INVAL;
    }
  else
    for (dev = first_device; dev; dev = dev->next)
      if (strcmp (dev->name, nd_name) == 0)
	break;

  if (!dev)
    {
      DBG (1,
	   "sane_open: device %s not found, trying to register it anyway\n",
	   nd_name);
#if WITH_AVAHI
      avahi_threaded_poll_lock (avahi_thread);
#endif /* WITH_AVAHI */
      status = add_device (nd_name, &dev);
#if WITH_AVAHI
      avahi_threaded_poll_unlock (avahi_thread);
#endif /* WITH_AVAHI */
      if (status != SANE_STATUS_GOOD)
	{
	  DBG (1, "sane_open: could not open device\n");
	  return status;
	}
    }
  else
    DBG (2, "sane_open: device found in list\n");

  if (dev->ctl < 0)
    {
      DBG (2, "sane_open: device not connected yet...\n");
      status = connect_dev (dev);
      if (status != SANE_STATUS_GOOD)
	{
	  DBG (1, "sane_open: could not connect to device\n");
	  return status;
	}
    }

  DBG (3, "sane_open: net_open\n");
  sanei_w_call (&dev->wire, SANE_NET_OPEN,
		(WireCodecFunc) sanei_w_string, &dev_name,
		(WireCodecFunc) sanei_w_open_reply, &reply);
  do
    {
      if (dev->wire.status != 0)
	{
	  DBG (1, "sane_open: open rpc call failed (%s)\n",
	       strerror (dev->wire.status));
	  return SANE_STATUS_IO_ERROR;
	}

      status = reply.status;
      handle = reply.handle;
      need_auth = (reply.resource_to_authorize != 0);

      if (need_auth)
	{
	  DBG (3, "sane_open: authorization required\n");
	  do_authorization (dev, reply.resource_to_authorize);

	  sanei_w_free (&dev->wire, (WireCodecFunc) sanei_w_open_reply,
			&reply);

	  if (dev->wire.direction != WIRE_DECODE)
	    sanei_w_set_dir (&dev->wire, WIRE_DECODE);
	  sanei_w_open_reply (&dev->wire, &reply);

	  continue;
	}
      else
	sanei_w_free (&dev->wire, (WireCodecFunc) sanei_w_open_reply, &reply);

      if (need_auth && !dev->auth_active)
	{
	  DBG (2, "sane_open: open cancelled\n");
	  return SANE_STATUS_CANCELLED;
	}

      if (status != SANE_STATUS_GOOD)
	{
	  DBG (1, "sane_open: remote open failed\n");
	  return reply.status;
	}
    }
  while (need_auth);

  s = malloc (sizeof (*s));
  if (!s)
    {
      DBG (1, "sane_open: not enough free memory\n");
      return SANE_STATUS_NO_MEM;
    }

  memset (s, 0, sizeof (*s));
  s->hw = dev;
  s->handle = handle;
  s->data = -1;
  s->next = first_handle;
  s->local_opt.desc = 0;
  s->local_opt.num_options = 0;

  DBG (3, "sane_open: getting option descriptors\n");
  status = fetch_options (s);
  if (status != SANE_STATUS_GOOD)
    {
      DBG (1, "sane_open: fetch_options failed (%s), closing device again\n",
	   sane_strstatus (status));

      sanei_w_call (&s->hw->wire, SANE_NET_CLOSE,
		    (WireCodecFunc) sanei_w_word, &s->handle,
		    (WireCodecFunc) sanei_w_word, &ack);

      free (s);

      return status;
    }

  first_handle = s;
  *meta_handle = s;

  DBG (3, "sane_open: success\n");
  return SANE_STATUS_GOOD;
}

void
sane_close (SANE_Handle handle)
{
  Net_Scanner *prev, *s;
  SANE_Word ack;
  int option_number;

  DBG (3, "sane_close: handle %p\n", handle);

  prev = 0;
  for (s = first_handle; s; s = s->next)
    {
      if (s == handle)
	break;
      prev = s;
    }
  if (!s)
    {
      DBG (1, "sane_close: invalid handle %p\n", handle);
      return;			/* oops, not a handle we know about */
    }
  if (prev)
    prev->next = s->next;
  else
    first_handle = s->next;

  if (s->opt.num_options)
    {
      DBG (2, "sane_close: removing cached option descriptors\n");
      sanei_w_set_dir (&s->hw->wire, WIRE_FREE);
      s->hw->wire.status = 0;
      sanei_w_option_descriptor_array (&s->hw->wire, &s->opt);
      if (s->hw->wire.status)
	DBG (1, "sane_close: couldn't free sanei_w_option_descriptor_array "
	     "(%s)\n", sane_strstatus (s->hw->wire.status));
    }

  DBG (2, "sane_close: removing local option descriptors\n");
  for (option_number = 0; option_number < s->local_opt.num_options;
       option_number++)
    free (s->local_opt.desc[option_number]);
  if (s->local_opt.desc)
    free (s->local_opt.desc);

  DBG (2, "sane_close: net_close\n");
  sanei_w_call (&s->hw->wire, SANE_NET_CLOSE,
		(WireCodecFunc) sanei_w_word, &s->handle,
		(WireCodecFunc) sanei_w_word, &ack);
  if (s->data >= 0)
    {
      DBG (2, "sane_close: closing data pipe\n");
      close (s->data);
    }
  free (s);
  DBG (2, "sane_close: done\n");
}

const SANE_Option_Descriptor *
sane_get_option_descriptor (SANE_Handle handle, SANE_Int option)
{
  Net_Scanner *s = handle;
  SANE_Status status;

  DBG (3, "sane_get_option_descriptor: option %d\n", option);

  if (!s->options_valid)
    {
      DBG (3, "sane_get_option_descriptor: getting option descriptors\n");
      status = fetch_options (s);
      if (status != SANE_STATUS_GOOD)
	{
	  DBG (1, "sane_get_option_descriptor: fetch_options failed (%s)\n",
	       sane_strstatus (status));
	  return 0;
	}
    }

  if (((SANE_Word) option >= s->opt.num_options) || (option < 0))
    {
      DBG (2, "sane_get_option_descriptor: invalid option number\n");
      return 0;
    }
  return s->local_opt.desc[option];
}

SANE_Status
sane_control_option (SANE_Handle handle, SANE_Int option,
		     SANE_Action action, void *value, SANE_Word * info)
{
  Net_Scanner *s = handle;
  SANE_Control_Option_Req req;
  SANE_Control_Option_Reply reply;
  SANE_Status status;
  size_t value_size;
  int need_auth;
  SANE_Word local_info;

  DBG (3, "sane_control_option: option %d, action %d\n", option, action);

  if (!s->options_valid)
    {
      DBG (1, "sane_control_option: FRONTEND BUG: option descriptors reload needed\n");
      return SANE_STATUS_INVAL;
    }

  if (((SANE_Word) option >= s->opt.num_options) || (option < 0))
    {
      DBG (1, "sane_control_option: invalid option number\n");
      return SANE_STATUS_INVAL;
    }

  switch (s->opt.desc[option]->type)
    {
    case SANE_TYPE_BUTTON:
    case SANE_TYPE_GROUP:	/* shouldn't happen... */
      /* the SANE standard defines that the option size of a BUTTON or
         GROUP is IGNORED.  */
      value_size = 0;
      break;
    case SANE_TYPE_STRING:	/* strings can be smaller than size */
      value_size = s->opt.desc[option]->size;
      if ((action == SANE_ACTION_SET_VALUE)
	  && (((SANE_Int) strlen ((SANE_String) value) + 1)
	      < s->opt.desc[option]->size))
	value_size = strlen ((SANE_String) value) + 1;
      break;
    default:
      value_size = s->opt.desc[option]->size;
      break;
    }

  /* Avoid leaking memory bits */
  if (value && (action != SANE_ACTION_SET_VALUE))
    memset (value, 0, value_size);

  /* for SET_AUTO the parameter ``value'' is ignored */
  if (action == SANE_ACTION_SET_AUTO)
    value_size = 0;

  req.handle = s->handle;
  req.option = option;
  req.action = action;
  req.value_type = s->opt.desc[option]->type;
  req.value_size = value_size;
  req.value = value;

  local_info = 0;

  DBG (3, "sane_control_option: remote control option\n");
  sanei_w_call (&s->hw->wire, SANE_NET_CONTROL_OPTION,
		(WireCodecFunc) sanei_w_control_option_req, &req,
		(WireCodecFunc) sanei_w_control_option_reply, &reply);

  do
    {
      status = reply.status;
      need_auth = (reply.resource_to_authorize != 0);
      if (need_auth)
	{
	  DBG (3, "sane_control_option: auth required\n");
	  do_authorization (s->hw, reply.resource_to_authorize);
	  sanei_w_free (&s->hw->wire,
			(WireCodecFunc) sanei_w_control_option_reply, &reply);

	  sanei_w_set_dir (&s->hw->wire, WIRE_DECODE);

	  sanei_w_control_option_reply (&s->hw->wire, &reply);
	  continue;

	}
      else if (status == SANE_STATUS_GOOD)
	{
	  local_info = reply.info;

	  if (info)
	    *info = reply.info;
	  if (value_size > 0)
	    {
	      if ((SANE_Word) value_size == reply.value_size)
		memcpy (value, reply.value, reply.value_size);
	      else
		DBG (1, "sane_control_option: size changed from %d to %d\n",
		     s->opt.desc[option]->size, reply.value_size);
	    }

	  if (reply.info & SANE_INFO_RELOAD_OPTIONS)
	    s->options_valid = 0;
	}
      sanei_w_free (&s->hw->wire,
		    (WireCodecFunc) sanei_w_control_option_reply, &reply);
      if (need_auth && !s->hw->auth_active)
	return SANE_STATUS_CANCELLED;
    }
  while (need_auth);

  DBG (2, "sane_control_option: remote done (%s, info %x)\n", sane_strstatus (status), local_info);

  if ((status == SANE_STATUS_GOOD) && (info == NULL) && (local_info & SANE_INFO_RELOAD_OPTIONS))
    {
      DBG (2, "sane_control_option: reloading options as frontend does not care\n");

      status = fetch_options (s);

      DBG (2, "sane_control_option: reload done (%s)\n", sane_strstatus (status));
    }

  DBG (2, "sane_control_option: done (%s, info %x)\n", sane_strstatus (status), local_info);

  return status;
}

SANE_Status
sane_get_parameters (SANE_Handle handle, SANE_Parameters * params)
{
  Net_Scanner *s = handle;
  SANE_Get_Parameters_Reply reply;
  SANE_Status status;

  DBG (3, "sane_get_parameters\n");

  if (!params)
    {
      DBG (1, "sane_get_parameters: parameter params not supplied\n");
      return SANE_STATUS_INVAL;
    }

  DBG (3, "sane_get_parameters: remote get parameters\n");
  sanei_w_call (&s->hw->wire, SANE_NET_GET_PARAMETERS,
		(WireCodecFunc) sanei_w_word, &s->handle,
		(WireCodecFunc) sanei_w_get_parameters_reply, &reply);

  status = reply.status;
  *params = reply.params;
  depth = reply.params.depth;
  sanei_w_free (&s->hw->wire,
		(WireCodecFunc) sanei_w_get_parameters_reply, &reply);

  DBG (3, "sane_get_parameters: returned status %s\n",
       sane_strstatus (status));
  return status;
}

#ifdef NET_USES_AF_INDEP
SANE_Status
sane_start (SANE_Handle handle)
{
  Net_Scanner *s = handle;
  SANE_Start_Reply reply;
  struct sockaddr_in sin;
  struct sockaddr *sa;
#ifdef ENABLE_IPV6
  struct sockaddr_in6 sin6;
#endif /* ENABLE_IPV6 */
  SANE_Status status;
  int fd, need_auth;
  socklen_t len;
  uint16_t port;			/* Internet-specific */


  DBG (3, "sane_start\n");

  hang_over = -1;
  left_over = -1;

  if (s->data >= 0)
    {
      DBG (2, "sane_start: data pipe already exists\n");
      return SANE_STATUS_INVAL;
    }

  /* Do this ahead of time so in case anything fails, we can
     recover gracefully (without hanging our server).  */

  switch (s->hw->addr_used->ai_family)
    {
      case AF_INET:
	len = sizeof (sin);
	sa = (struct sockaddr *) &sin;
	break;
#ifdef ENABLE_IPV6
      case AF_INET6:
	len = sizeof (sin6);
	sa = (struct sockaddr *) &sin6;
	break;
#endif /* ENABLE_IPV6 */
      default:
	DBG (1, "sane_start: unknown address family : %d\n",
	     s->hw->addr_used->ai_family);
	return SANE_STATUS_INVAL;
    }

  if (getpeername (s->hw->ctl, sa, &len) < 0)
    {
      DBG (1, "sane_start: getpeername() failed (%s)\n", strerror (errno));
      return SANE_STATUS_IO_ERROR;
    }

  fd = socket (s->hw->addr_used->ai_family, SOCK_STREAM, 0);
  if (fd < 0)
    {
      DBG (1, "sane_start: socket() failed (%s)\n", strerror (errno));
      return SANE_STATUS_IO_ERROR;
    }

  DBG (3, "sane_start: remote start\n");
  sanei_w_call (&s->hw->wire, SANE_NET_START,
		(WireCodecFunc) sanei_w_word, &s->handle,
		(WireCodecFunc) sanei_w_start_reply, &reply);
  do
    {
      status = reply.status;
      port = reply.port;
      if (reply.byte_order == 0x1234)
	{
	  server_big_endian = 0;
	  DBG (1, "sane_start: server has little endian byte order\n");
	}
      else
	{
	  server_big_endian = 1;
	  DBG (1, "sane_start: server has big endian byte order\n");
	}

      need_auth = (reply.resource_to_authorize != 0);
      if (need_auth)
	{
	  DBG (3, "sane_start: auth required\n");
	  do_authorization (s->hw, reply.resource_to_authorize);

	  sanei_w_free (&s->hw->wire,
			(WireCodecFunc) sanei_w_start_reply, &reply);

	  sanei_w_set_dir (&s->hw->wire, WIRE_DECODE);

	  sanei_w_start_reply (&s->hw->wire, &reply);

	  continue;
	}
      sanei_w_free (&s->hw->wire, (WireCodecFunc) sanei_w_start_reply,
		    &reply);
      if (need_auth && !s->hw->auth_active)
	return SANE_STATUS_CANCELLED;

      if (status != SANE_STATUS_GOOD)
	{
	  DBG (1, "sane_start: remote start failed (%s)\n",
	       sane_strstatus (status));
	  close (fd);
	  return status;
	}
    }
  while (need_auth);
  DBG (3, "sane_start: remote start finished, data at port %hu\n", port);

  switch (s->hw->addr_used->ai_family)
    {
      case AF_INET:
	sin.sin_port = htons (port);
	break;
#ifdef ENABLE_IPV6
      case AF_INET6:
	sin6.sin6_port = htons (port);
	break;
#endif /* ENABLE_IPV6 */
    }

  if (connect (fd, sa, len) < 0)
    {
      DBG (1, "sane_start: connect() failed (%s)\n", strerror (errno));
      close (fd);
      return SANE_STATUS_IO_ERROR;
    }
  shutdown (fd, 1);
  s->data = fd;
  s->reclen_buf_offset = 0;
  s->bytes_remaining = 0;
  DBG (3, "sane_start: done (%s)\n", sane_strstatus (status));
  return status;
}

#else /* !NET_USES_AF_INDEP */

SANE_Status
sane_start (SANE_Handle handle)
{
  Net_Scanner *s = handle;
  SANE_Start_Reply reply;
  struct sockaddr_in sin;
  SANE_Status status;
  int fd, need_auth;
  socklen_t len;
  uint16_t port;			/* Internet-specific */


  DBG (3, "sane_start\n");

  hang_over = -1;
  left_over = -1;

  if (s->data >= 0)
    {
      DBG (2, "sane_start: data pipe already exists\n");
      return SANE_STATUS_INVAL;
    }

  /* Do this ahead of time so in case anything fails, we can
     recover gracefully (without hanging our server).  */
  len = sizeof (sin);
  if (getpeername (s->hw->ctl, (struct sockaddr *) &sin, &len) < 0)
    {
      DBG (1, "sane_start: getpeername() failed (%s)\n", strerror (errno));
      return SANE_STATUS_IO_ERROR;
    }

  fd = socket (s->hw->addr.sa_family, SOCK_STREAM, 0);
  if (fd < 0)
    {
      DBG (1, "sane_start: socket() failed (%s)\n", strerror (errno));
      return SANE_STATUS_IO_ERROR;
    }

  DBG (3, "sane_start: remote start\n");
  sanei_w_call (&s->hw->wire, SANE_NET_START,
		(WireCodecFunc) sanei_w_word, &s->handle,
		(WireCodecFunc) sanei_w_start_reply, &reply);
  do
    {

      status = reply.status;
      port = reply.port;
      if (reply.byte_order == 0x1234)
	{
	  server_big_endian = 0;
	  DBG (1, "sane_start: server has little endian byte order\n");
	}
      else
	{
	  server_big_endian = 1;
	  DBG (1, "sane_start: server has big endian byte order\n");
	}

      need_auth = (reply.resource_to_authorize != 0);
      if (need_auth)
	{
	  DBG (3, "sane_start: auth required\n");
	  do_authorization (s->hw, reply.resource_to_authorize);

	  sanei_w_free (&s->hw->wire,
			(WireCodecFunc) sanei_w_start_reply, &reply);

	  sanei_w_set_dir (&s->hw->wire, WIRE_DECODE);

	  sanei_w_start_reply (&s->hw->wire, &reply);

	  continue;
	}
      sanei_w_free (&s->hw->wire, (WireCodecFunc) sanei_w_start_reply,
		    &reply);
      if (need_auth && !s->hw->auth_active)
	return SANE_STATUS_CANCELLED;

      if (status != SANE_STATUS_GOOD)
	{
	  DBG (1, "sane_start: remote start failed (%s)\n",
	       sane_strstatus (status));
	  close (fd);
	  return status;
	}
    }
  while (need_auth);
  DBG (3, "sane_start: remote start finished, data at port %hu\n", port);
  sin.sin_port = htons (port);

  if (connect (fd, (struct sockaddr *) &sin, len) < 0)
    {
      DBG (1, "sane_start: connect() failed (%s)\n", strerror (errno));
      close (fd);
      return SANE_STATUS_IO_ERROR;
    }
  shutdown (fd, 1);
  s->data = fd;
  s->reclen_buf_offset = 0;
  s->bytes_remaining = 0;
  DBG (3, "sane_start: done (%s)\n", sane_strstatus (status));
  return status;
}
#endif /* NET_USES_AF_INDEP */


SANE_Status
sane_read (SANE_Handle handle, SANE_Byte * data, SANE_Int max_length,
	   SANE_Int * length)
{
  Net_Scanner *s = handle;
  ssize_t nread;
  SANE_Int cnt;
  SANE_Int start_cnt;
  SANE_Int end_cnt;
  SANE_Byte swap_buf;
  SANE_Byte temp_hang_over;
  int is_even;

  DBG (3, "sane_read: handle=%p, data=%p, max_length=%d, length=%p\n",
       handle, (void *) data, max_length, (void *) length);
  if (!length)
    {
      DBG (1, "sane_read: length == NULL\n");
      return SANE_STATUS_INVAL;
    }

  is_even = 1;
  *length = 0;

  /* If there's a left over, i.e. a byte already in the correct byte order,
     return it immediately; otherwise read may fail with a SANE_STATUS_EOF and
     the caller never can read the last byte */
  if ((depth == 16) && (server_big_endian != client_big_endian))
    {
      if (left_over > -1)
	{
	  DBG (3, "sane_read: left_over from previous call, return "
	       "immediately\n");
	  /* return the byte, we've currently scanned; hang_over becomes
	     left_over */
	  *data = (SANE_Byte) left_over;
	  left_over = -1;
	  *length = 1;
	  return SANE_STATUS_GOOD;
	}
    }

  if (s->data < 0)
    {
      DBG (1, "sane_read: data pipe doesn't exist, scan cancelled?\n");
      return SANE_STATUS_CANCELLED;
    }

  if (s->bytes_remaining == 0)
    {
      /* boy, is this painful or what? */

      DBG (4, "sane_read: reading packet length\n");
      nread = read (s->data, s->reclen_buf + s->reclen_buf_offset,
		    4 - s->reclen_buf_offset);
      if (nread < 0)
	{
	  DBG (3, "sane_read: read failed (%s)\n", strerror (errno));
	  if (errno == EAGAIN)
	    {
	      DBG (3, "sane_read: try again later\n");
	      return SANE_STATUS_GOOD;
	    }
	  else
	    {
	      DBG (1, "sane_read: cancelling read\n");
	      do_cancel (s);
	      return SANE_STATUS_IO_ERROR;
	    }
	}
      DBG (4, "sane_read: read %lu bytes, %d from 4 total\n", (u_long) nread,
	   s->reclen_buf_offset);
      s->reclen_buf_offset += nread;
      if (s->reclen_buf_offset < 4)
	{
	  DBG (4, "sane_read: enough for now\n");
	  return SANE_STATUS_GOOD;
	}

      s->reclen_buf_offset = 0;
      s->bytes_remaining = (((u_long) s->reclen_buf[0] << 24)
			    | ((u_long) s->reclen_buf[1] << 16)
			    | ((u_long) s->reclen_buf[2] << 8)
			    | ((u_long) s->reclen_buf[3] << 0));
      DBG (3, "sane_read: next record length=%ld bytes\n",
	   (long) s->bytes_remaining);
      if (s->bytes_remaining == 0xffffffff)
	{
	  char ch;

	  DBG (2, "sane_read: received error signal\n");

	  /* turn off non-blocking I/O (s->data will be closed anyhow): */
	  fcntl (s->data, F_SETFL, 0);

	  /* read the status byte: */
	  if (read (s->data, &ch, sizeof (ch)) != 1)
	    {
	      DBG (1, "sane_read: failed to read error code\n");
	      ch = SANE_STATUS_IO_ERROR;
	    }
	  DBG (1, "sane_read: error code %s\n",
	       sane_strstatus ((SANE_Status) ch));
	  do_cancel (s);
	  return (SANE_Status) ch;
	}
    }

  if (max_length > (SANE_Int) s->bytes_remaining)
    max_length = s->bytes_remaining;

  nread = read (s->data, data, max_length);

  if (nread < 0)
    {
      DBG (2, "sane_read: error code %s\n", strerror (errno));
      if (errno == EAGAIN)
	return SANE_STATUS_GOOD;
      else
	{
	  DBG (1, "sane_read: cancelling scan\n");
	  do_cancel (s);
	  return SANE_STATUS_IO_ERROR;
	}
    }

  s->bytes_remaining -= nread;

  *length = nread;
  /* Check whether we are scanning with a depth of 16 bits/pixel and whether
     server and client have different byte order. If this is true, then it's
     necessary to check whether read returned an odd number. If an odd number
     has been returned, we must save the last byte.
  */
  if ((depth == 16) && (server_big_endian != client_big_endian))
    {
      DBG (1,"sane_read: client/server have different byte order; "
	   "must swap\n");
      /* special case: 1 byte scanned and hang_over */
      if ((nread == 1) && (hang_over > -1))
	{
	  /* return the byte, we've currently scanned; hang_over becomes
	     left_over */
	  left_over = hang_over;
	  hang_over = -1;
	  return SANE_STATUS_GOOD;
	}
      /* check whether an even or an odd number of bytes has been scanned */
      if ((nread % 2) == 0)
        is_even = 1;
      else
        is_even = 0;
      /* check, whether there's a hang over from a previous call;
	 in this case we memcopy the data up one byte */
      if ((nread > 1) && (hang_over > -1))
	{
	  /* store last byte */
	  temp_hang_over = *(data + nread - 1);
	  memmove (data + 1, data, nread - 1);
	  *data = (SANE_Byte) hang_over;
	  /* what happens with the last byte depends on whether the number
	     of bytes is even or odd */
	  if (is_even == 1)
	    {
	      /* number of bytes is even; no new hang_over, exchange last
		 byte with hang over; last byte becomes left_over */
	      left_over = *(data + nread - 1);
	      *(data + nread - 1) = temp_hang_over;
	      hang_over = -1;
	      start_cnt = 0;
	      /* last byte already swapped */
	      end_cnt = nread - 2;
	    }
	  else
	    {
	      /* number of bytes is odd; last byte becomes new hang_over */
	      hang_over = temp_hang_over;
	      left_over = -1;
	      start_cnt = 0;
	      end_cnt = nread - 1;
	    }
	}
      else if (nread == 1)
	{
	  /* if only one byte has been read, save it as hang_over and return
	     length=0 */
	  hang_over = (int) *data;
	  *length = 0;
	  return SANE_STATUS_GOOD;
	}
      else
	{
	  /* no hang_over; test for even or odd byte number */
	  if(is_even == 1)
	    {
	      start_cnt = 0;
	      end_cnt = *length;
	    }
	  else
	    {
	      start_cnt = 0;
	      hang_over = *(data + *length - 1);
	      *length -= 1;
	      end_cnt = *length;
	    }
	}
      /* swap the bytes */
      for (cnt = start_cnt; cnt < end_cnt - 1; cnt += 2)
	{
	  swap_buf = *(data + cnt);
	  *(data + cnt) = *(data + cnt + 1);
	  *(data + cnt + 1) = swap_buf;
	}
    }
  DBG (3, "sane_read: %lu bytes read, %lu remaining\n", (u_long) nread,
       (u_long) s->bytes_remaining);

  return SANE_STATUS_GOOD;
}

void
sane_cancel (SANE_Handle handle)
{
  Net_Scanner *s = handle;
  SANE_Word ack;

  DBG (3, "sane_cancel: sending net_cancel\n");

  sanei_w_call (&s->hw->wire, SANE_NET_CANCEL,
		(WireCodecFunc) sanei_w_word, &s->handle,
		(WireCodecFunc) sanei_w_word, &ack);
  do_cancel (s);
  DBG (4, "sane_cancel: done\n");
}

SANE_Status
sane_set_io_mode (SANE_Handle handle, SANE_Bool non_blocking)
{
  Net_Scanner *s = handle;

  DBG (3, "sane_set_io_mode: non_blocking = %d\n", non_blocking);
  if (s->data < 0)
    {
      DBG (1, "sane_set_io_mode: pipe doesn't exist\n");
      return SANE_STATUS_INVAL;
    }

  if (fcntl (s->data, F_SETFL, non_blocking ? O_NONBLOCK : 0) < 0)
    {
      DBG (1, "sane_set_io_mode: fcntl failed (%s)\n", strerror (errno));
      return SANE_STATUS_IO_ERROR;
    }

  return SANE_STATUS_GOOD;
}

SANE_Status
sane_get_select_fd (SANE_Handle handle, SANE_Int * fd)
{
  Net_Scanner *s = handle;

  DBG (3, "sane_get_select_fd\n");

  if (s->data < 0)
    {
      DBG (1, "sane_get_select_fd: pipe doesn't exist\n");
      return SANE_STATUS_INVAL;
    }

  *fd = s->data;
  DBG (3, "sane_get_select_fd: done; *fd = %d\n", *fd);
  return SANE_STATUS_GOOD;
}