/* $XConsortium: access.c,v 1.5 95/01/27 15:05:53 kaleb Exp $ */
/* $XFree86: xc/workInProgress/lbx/programs/lbxproxy/os/access.c,v 3.2 1995/01/28 16:24:00 dawes Exp $ */
/***********************************************************

Copyright (c) 1987  X Consortium

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
X CONSORTIUM BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

Except as contained in this notice, the name of the X Consortium shall not be
used in advertising or otherwise to promote the sale, use or other dealings
in this Software without prior written authorization from the X Consortium.


Copyright 1987 by Digital Equipment Corporation, Maynard, Massachusetts.

                        All Rights Reserved

Permission to use, copy, modify, and distribute this software and its 
documentation for any purpose and without fee is hereby granted, 
provided that the above copyright notice appear in all copies and that
both that copyright notice and this permission notice appear in 
supporting documentation, and that the name of Digital not be
used in advertising or publicity pertaining to distribution of the
software without specific, written prior permission.  

DIGITAL DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING
ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL
DIGITAL BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR
ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
SOFTWARE.

******************************************************************/

#include <stdio.h>
#include "Xos.h"
#include <X11/Xauth.h>
#include "X.h"
#include "Xproto.h"
#include "misc.h"
#include "site.h"
#include <errno.h>
#ifdef ESIX
#include <lan/socket.h>
#else
#include <sys/socket.h>
#endif
#include <sys/ioctl.h>
#include <ctype.h>

#if defined(TCPCONN) || defined(ISC)
#include <netinet/in.h>
#endif /* TCPCONN || ISC */
#ifdef DNETCONN
#include <netdnet/dn.h>
#include <netdnet/dnetdb.h>
#endif

#ifdef hpux
# include <sys/utsname.h>
# ifdef HAS_IFREQ
#  include <net/if.h>
# endif
#else
#if defined(SVR4) || (defined(SYSV) && defined(i386))
# include <sys/utsname.h>
#endif
#if defined(SYSV) && defined(i386)
# include <sys/stream.h>
#endif
#ifdef ESIX
# include <lan/if.h>
#else
# include <net/if.h>
#endif
#endif /* hpux */

#ifdef SVR4
#include <sys/sockio.h>
#endif

#ifdef ESIX
#include <lan/netdb.h>
#else
#include <netdb.h>
#endif

#include "dixstruct.h"
#include "osdep.h"

Bool defeatAccessControl = FALSE;

#define acmp(a1, a2, len) memcmp((char *)(a1), (char *)(a2), len)
#define acopy(a1, a2, len) memmove((char *)(a2), (char *)(a1), len)
#define addrEqual(fam, address, length, host) \
			 ((fam) == (host)->family &&\
			  (length) == (host)->len &&\
			  !acmp (address, (host)->addr, length))

#ifdef LOCALCONN
extern int xlocal_getpeername();
#define	getpeername xlocal_getpeername
#endif

#ifdef hpux
#define getpeername(fd, from, fromlen)	hpux_getpeername(fd, from, fromlen)
#endif

static int ConvertAddr(
#if NeedFunctionPrototypes
    struct sockaddr */*saddr*/,
    int */*len*/,
    pointer */*addr*/
#endif
);

static int CheckAddr(
#if NeedFunctionPrototypes
    int /*family*/,
    pointer /*pAddr*/,
    unsigned /*length*/
#endif
);

static Bool NewHost(
#if NeedFunctionPrototypes
    int /*family*/,
    pointer /*addr*/,
    int /*len*/
#endif
);

typedef struct _host {
	short		family;
	short		len;
	unsigned char	*addr;
	struct _host *next;
} HOST;

#define MakeHost(h,l)	(h)=(HOST *) xalloc(sizeof *(h)+(l));\
			(h)->addr=(unsigned char *) ((h) + 1);
#define FreeHost(h)	xfree(h)
static HOST *selfhosts = NULL;
static HOST *validhosts = NULL;
static int AccessEnabled = DEFAULT_ACCESS_CONTROL;
static int LocalHostEnabled = FALSE;
static int UsingXdmcp = FALSE;

/*
 * called when authorization is not enabled to add the
 * local host to the access list
 */

void
EnableLocalHost ()
{
    if (!UsingXdmcp)
    {
	LocalHostEnabled = TRUE;
	AddLocalHosts ();
    }
}

/*
 * called when authorization is enabled to keep us secure
 */
void
DisableLocalHost ()
{
    HOST *self;

    LocalHostEnabled = FALSE;
    for (self = selfhosts; self; self = self->next)
	(void) RemoveHost (NULL, self->family, self->len, self->addr);
}

/*
 * called at init time when XDMCP will be used; xdmcp always
 * adds local hosts manually when needed
 */

void
AccessUsingXdmcp ()
{
    UsingXdmcp = TRUE;
    LocalHostEnabled = FALSE;
}

#if !defined(SIOCGIFCONF) || (defined (hpux) && ! defined (HAS_IFREQ))
/* Define this host for access control.  Find all the hosts the OS knows about 
 * for this fd and add them to the selfhosts list.
 */
void
DefineSelf (fd)
    int fd;
{
#if !defined(TCPCONN) && !defined(UNIXCONN)
    return;
#else
    register int n;
    int	len;
    caddr_t	addr;
    int		family;
    register HOST	*host;

#ifdef __386BSD__
    char name[100];
#else
    struct utsname name;
#endif
    register struct hostent  *hp;

    union {
	struct  sockaddr   sa;
	struct  sockaddr_in  in;
    } saddr;
	
    struct	sockaddr_in	*inetaddr;

#ifdef __386BSD__
    if (gethostname (name, sizeof name) < 0)
	    hp = NULL;
    else
	    hp = gethostbyname (name);
#else
    /* Why not use gethostname()?  Well, at least on my system, I've had to
     * make an ugly kernel patch to get a name longer than 8 characters, and
     * uname() lets me access to the whole string (it smashes release, you
     * see), whereas gethostname() kindly truncates it for me.
     */
    uname(&name);
    hp = gethostbyname (name.nodename);
#endif
    if (hp != NULL)
    {
	saddr.sa.sa_family = hp->h_addrtype;
	inetaddr = (struct sockaddr_in *) (&(saddr.sa));
	acopy ( hp->h_addr, &(inetaddr->sin_addr), hp->h_length);
	len = sizeof(saddr.sa);
	family = ConvertAddr ( &(saddr.sa), &len, (pointer *)&addr);
	if ( family != -1 && family != FamilyLocal )
	{
	    for (host = selfhosts;
		 host && !addrEqual (family, addr, len, host);
		 host = host->next) ;
	    if (!host)
	    {
		/* add this host to the host list.	*/
		MakeHost(host,len)
		if (host)
		{
		    host->family = family;
		    host->len = len;
		    acopy ( addr, host->addr, len);
		    host->next = selfhosts;
		    selfhosts = host;
		}
	    }
	}
    }
    /*
     * now add a host of family FamilyLocalHost...
     */
    for (host = selfhosts;
	 host && !addrEqual(FamilyLocalHost, "", 0, host);
	 host = host->next);
    if (!host)
    {
	MakeHost(host, 0);
	if (host)
	{
	    host->family = FamilyLocalHost;
	    host->len = 0;
	    acopy("", host->addr, 0);
	    host->next = selfhosts;
	    selfhosts = host;
	}
    }
#endif /* !TCPCONN && !UNIXCONN */
}

#else
/* Define this host for access control.  Find all the hosts the OS knows about 
 * for this fd and add them to the selfhosts list.
 */
void
DefineSelf (fd)
    int fd;
{
    char		buf[2048];
    struct ifconf	ifc;
    register int	n;
    int 		len;
    unsigned char *	addr;
    int 		family;
    register HOST 	*host;
    register struct ifreq *ifr;
    
#ifdef DNETCONN
    struct dn_naddr *dnaddr = getnodeadd(0);
    /*
     * AF_DECnet may not be listed in the interface list.  Instead use
     * the supported library call to find out the local address (if any).
     */
    if (dnaddr)
    {    
	addr = (unsigned char *) dnaddr;
	len = dnaddr->a_len + sizeof(dnaddr->a_len);
	family = FamilyDECnet;
	for (host = selfhosts;
	     host && !addrEqual (family, addr, len, host);
	     host = host->next)
	    ;
        if (!host)
	{
	    MakeHost(host,len)
	    if (host)
	    {
		host->family = family;
		host->len = len;
		acopy(addr, host->addr, len);
		host->next = selfhosts;
		selfhosts = host;
	    }
	}
    }
#endif
    ifc.ifc_len = sizeof (buf);
    ifc.ifc_buf = buf;
    if (ioctl (fd, (int) SIOCGIFCONF, (pointer) &ifc) < 0)
        Error ("Getting interface configuration");
    for (ifr = ifc.ifc_req
#if defined (__bsdi__) || defined(__NetBSD__)
	 ; (char *)ifr < ifc.ifc_buf + ifc.ifc_len;
	 ifr = (struct ifreq *)((char *)ifr + sizeof (struct ifreq) +
		(ifr->ifr_addr.sa_len > sizeof (ifr->ifr_addr) ?
		 ifr->ifr_addr.sa_len - sizeof (ifr->ifr_addr) : 0))
#else
	 , n = ifc.ifc_len / sizeof (struct ifreq); --n >= 0; ifr++
#endif
	 )
    {
	len = sizeof(ifr->ifr_addr);
#ifdef DNETCONN
	/*
	 * DECnet was handled up above.
	 */
	if (ifr->ifr_addr.sa_family == AF_DECnet)
	    continue;
#endif /* DNETCONN */
	family = ConvertAddr (&ifr->ifr_addr, &len, (pointer *)&addr);
        if (family == -1 || family == FamilyLocal)
	    continue;
        for (host = selfhosts;
 	     host && !addrEqual (family, addr, len, host);
	     host = host->next)
	    ;
        if (host)
	    continue;
	MakeHost(host,len)
	if (host)
	{
	    host->family = family;
	    host->len = len;
	    acopy(addr, host->addr, len);
	    host->next = selfhosts;
	    selfhosts = host;
	}
#ifdef XDMCP
	{
	    struct sockaddr broad_addr;

	    /*
	     * If this isn't an Internet Address, don't register it.
	     */
	    if (family != FamilyInternet)
		continue;

	    /*
 	     * ignore 'localhost' entries as they're not useful
	     * on the other end of the wire
	     */
	    if (len == 4 &&
		addr[0] == 127 && addr[1] == 0 &&
		addr[2] == 0 && addr[3] == 1)
		continue;

	    XdmcpRegisterConnection (family, (char *)addr, len);
	    broad_addr = ifr->ifr_addr;
	    ((struct sockaddr_in *) &broad_addr)->sin_addr.s_addr =
		htonl (INADDR_BROADCAST);
#ifdef SIOCGIFBRDADDR
	    {
	    	struct ifreq    broad_req;
    
	    	broad_req = *ifr;
		if (ioctl (fd, SIOCGIFFLAGS, (char *) &broad_req) != -1 &&
		    (broad_req.ifr_flags & IFF_BROADCAST) &&
		    (broad_req.ifr_flags & IFF_UP)
		    )
		{
		    broad_req = *ifr;
		    if (ioctl (fd, SIOCGIFBRDADDR, &broad_req) != -1)
			broad_addr = broad_req.ifr_addr;
		    else
			continue;
		}
		else
		    continue;
	    }
#endif
	    XdmcpRegisterBroadcastAddress ((struct sockaddr_in *) &broad_addr);
	}
#endif
    }
    /*
     * add something of FamilyLocalHost
     */
    for (host = selfhosts;
	 host && !addrEqual(FamilyLocalHost, "", 0, host);
	 host = host->next);
    if (!host)
    {
	MakeHost(host, 0);
	if (host)
	{
	    host->family = FamilyLocalHost;
	    host->len = 0;
	    acopy("", host->addr, 0);
	    host->next = selfhosts;
	    selfhosts = host;
	}
    }
}
#endif /* hpux && !HAS_IFREQ */

#ifdef XDMCP
void
AugmentSelf(from, len)
    pointer	from;
    int		    len;
{
    int family;
    pointer addr;
    register HOST *host;

    family = ConvertAddr(from, &len, (pointer *)&addr);
    if (family == -1 || family == FamilyLocal)
	return;
    for (host = selfhosts; host; host = host->next)
    {
	if (addrEqual(family, addr, len, host))
	    return;
    }
    MakeHost(host,len)
    if (!host)
	return;
    host->family = family;
    host->len = len;
    acopy(addr, host->addr, len);
    host->next = selfhosts;
    selfhosts = host;
}
#endif

void
AddLocalHosts ()
{
    HOST    *self;

    for (self = selfhosts; self; self = self->next)
	(void) NewHost (self->family, self->addr, self->len);
}

/* Reset access control list to initial hosts */
void
ResetHosts (display)
    char *display;
{
    register HOST	*host;
    char                lhostname[120], ohostname[120];
    char 		*hostname = ohostname;
    char		fname[32];
    FILE		*fd;
    char		*ptr;
    int                 i, hostlen;
    union {
        struct sockaddr	sa;
#ifdef TCPCONN
        struct sockaddr_in in;
#endif /* TCPCONN */
#ifdef DNETCONN
        struct sockaddr_dn dn;
#endif
    } 			saddr;
#ifdef DNETCONN
    struct nodeent 	*np;
    struct dn_naddr 	dnaddr, *dnaddrp, *dnet_addr();
#endif
#ifdef K5AUTH
    krb5_principal      princ;
    krb5_data		kbuf;
#endif
    int			family;
    pointer		addr;
    int 		len;
    register struct hostent *hp;

    AccessEnabled = defeatAccessControl ? FALSE : DEFAULT_ACCESS_CONTROL;
    LocalHostEnabled = FALSE;
    while (host = validhosts)
    {
        validhosts = host->next;
        FreeHost (host);
    }
    strcpy (fname, "/etc/X");
    strcat (fname, display);
    strcat (fname, ".hosts");
    if (fd = fopen (fname, "r")) 
    {
        while (fgets (ohostname, sizeof (ohostname), fd))
	{
	if (*ohostname == '#')
	    continue;
    	if (ptr = strchr(ohostname, '\n'))
    	    *ptr = 0;
        hostlen = strlen(ohostname) + 1;
        for (i = 0; i < hostlen; i++)
	    lhostname[i] = tolower(ohostname[i]);
	hostname = ohostname;
	if (!strncmp("local:", lhostname, 6))
	{
	    family = FamilyLocalHost;
	    NewHost(family, "", 0);
	}
#ifdef TCPCONN
	else if (!strncmp("inet:", lhostname, 5))
	{
	    family = FamilyInternet;
	    hostname = ohostname + 5;
	}
#endif
#ifdef DNETCONN
	else if (!strncmp("dnet:", lhostname, 5))
	{
	    family = FamilyDECnet;
	    hostname = ohostname + 5;
	}
#endif
#ifdef SECURE_RPC
	else if (!strncmp("nis:", lhostname, 4))
	{
	    family = FamilyNetname;
	    hostname = ohostname + 4;
	}
#endif
#ifdef K5AUTH
	else if (!strncmp("krb:", lhostname, 4))
	{
	    family = FamilyKrb5Principal;
	    hostname = ohostname + 4;
	}
#endif
#ifdef DNETCONN
    	if ((family == FamilyDECnet) ||
	    (ptr = strchr(hostname, ':')) && (*(ptr + 1) == ':') &&
	    !(*ptr = '\0'))	/* bash trailing colons if necessary */
	{
    	    /* node name (DECnet names end in "::") */
	    dnaddrp = dnet_addr(hostname);
    	    if (!dnaddrp && (np = getnodebyname (hostname)))
	    {
		/* node was specified by name */
		saddr.sa.sa_family = np->n_addrtype;
		len = sizeof(saddr.sa);
		if (ConvertAddr (&saddr.sa, &len, (pointer *)&addr) == FamilyDECnet)
		{
		    bzero ((char *) &dnaddr, sizeof (dnaddr));
		    dnaddr.a_len = np->n_length;
		    acopy (np->n_addr, dnaddr.a_addr, np->n_length);
		    dnaddrp = &dnaddr;
		}
    	    }
	    if (dnaddrp)
		(void) NewHost(FamilyDECnet, (pointer)dnaddrp,
			(int)(dnaddrp->a_len + sizeof(dnaddrp->a_len)));
    	}
	else
#endif /* DNETCONN */
#ifdef K5AUTH
	if (family == FamilyKrb5Principal)
	{
            krb5_parse_name(hostname, &princ);
	    XauKrb5Encode(princ, &kbuf);
	    (void) NewHost(FamilyKrb5Principal, kbuf.data, kbuf.length);
	    krb5_free_principal(princ);
        }
	else
#endif
#ifdef SECURE_RPC
	if ((family == FamilyNetname) || (strchr(hostname, '@')))
	{
	    SecureRPCInit ();
	    (void) NewHost (FamilyNetname, hostname, strlen (hostname));
	}
	else
#endif /* SECURE_RPC */
#ifdef TCPCONN
	{
    	    /* host name */
    	    if (family == FamilyInternet && (hp = gethostbyname (hostname)) ||
		 (hp = gethostbyname (hostname)))
	    {
    		saddr.sa.sa_family = hp->h_addrtype;
		len = sizeof(saddr.sa);
    		if ((family = ConvertAddr (&saddr.sa, &len, (pointer *)&addr)) != -1)
		{
#ifdef h_addr				/* new 4.3bsd version of gethostent */
		    char **list;

		    /* iterate over the addresses */
		    for (list = hp->h_addr_list; *list; list++)
			(void) NewHost (family, (pointer)*list, len);
#else
    		    (void) NewHost (family, (pointer)hp->h_addr, len);
#endif
		}
    	    }
        }
#endif /* TCPCONN */
	family = FamilyWild;
        }
        fclose (fd);
    }
}

static Bool
AuthorizedClient(client)
    ClientPtr client;
{
    int    		alen, family;
    struct sockaddr	from;
    pointer		addr;
    register HOST	*host;

    if (!client || defeatAccessControl)
	return TRUE;
    alen = sizeof (from);
    if (!getpeername (((OsCommPtr)client->osPrivate)->fd, &from, &alen))
    {
	family = ConvertAddr (&from, &alen, (pointer *)&addr);
	if (family == -1)
	    return FALSE;
	if (family == FamilyLocal)
	    return TRUE;
	for (host = selfhosts; host; host = host->next)
	{
	    if (addrEqual (family, addr, alen, host))
		return TRUE;
	}
    }
    return FALSE;
}

/* Add a host to the access control list.  This is the external interface
 * called from the dispatcher */

int
AddHost (client, family, length, pAddr)
    ClientPtr		client;
    int                 family;
    unsigned            length;        /* of bytes in pAddr */
    pointer             pAddr;
{
    int			len;

    if (!AuthorizedClient(client))
	return(BadAccess);
    switch (family) {
    case FamilyLocalHost:
	len = length;
	LocalHostEnabled = TRUE;
	break;
#ifdef K5AUTH
    case FamilyKrb5Principal:
        len = length;
        break;
#endif
#ifdef SECURE_RPC
    case FamilyNetname:
	len = length;
	SecureRPCInit ();
	break;
#endif
    case FamilyInternet:
    case FamilyDECnet:
    case FamilyChaos:
	if ((len = CheckAddr (family, pAddr, length)) < 0)
	{
	    client->errorValue = length;
	    return (BadValue);
	}
	break;
    case FamilyLocal:
    default:
	client->errorValue = family;
	return (BadValue);
    }
    if (NewHost (family, pAddr, len))
	return Success;
    return BadAlloc;
}

Bool
ForEachHostInFamily (family, func, closure)
    int	    family;
    Bool    (*func)();
    pointer closure;
{
    HOST    *host;

    for (host = validhosts; host; host = host->next)
	if (family == host->family && func (host->addr, host->len, closure))
	    return TRUE;
    return FALSE;
}

/* Add a host to the access control list. This is the internal interface 
 * called when starting or resetting the server */
static Bool
NewHost (family, addr, len)
    int		family;
    pointer	addr;
    int		len;
{
    register HOST *host;

    for (host = validhosts; host; host = host->next)
    {
        if (addrEqual (family, addr, len, host))
	    return TRUE;
    }
    MakeHost(host,len)
    if (!host)
	return FALSE;
    host->family = family;
    host->len = len;
    acopy(addr, host->addr, len);
    host->next = validhosts;
    validhosts = host;
    return TRUE;
}

/* Remove a host from the access control list */

int
RemoveHost (client, family, length, pAddr)
    ClientPtr		client;
    int                 family;
    unsigned            length;        /* of bytes in pAddr */
    pointer             pAddr;
{
    int			len;
    register HOST	*host, **prev;

    if (!AuthorizedClient(client))
	return(BadAccess);
    switch (family) {
    case FamilyLocalHost:
	len = length;
	LocalHostEnabled = FALSE;
	break;
#ifdef K5AUTH
    case FamilyKrb5Principal:
        len = length;
	break;
#endif
#ifdef SECURE_RPC
    case FamilyNetname:
	len = length;
	break;
#endif
    case FamilyInternet:
    case FamilyDECnet:
    case FamilyChaos:
    	if ((len = CheckAddr (family, pAddr, length)) < 0)
    	{
	    client->errorValue = length;
            return(BadValue);
    	}
	break;
    case FamilyLocal:
    default:
	client->errorValue = family;
        return(BadValue);
    }
    for (prev = &validhosts;
         (host = *prev) && (!addrEqual (family, pAddr, len, host));
         prev = &host->next)
        ;
    if (host)
    {
        *prev = host->next;
        FreeHost (host);
    }
    return (Success);
}

/* Get all hosts in the access control list */
int
GetHosts (data, pnHosts, pLen, pEnabled)
    pointer		*data;
    int			*pnHosts;
    int			*pLen;
    BOOL		*pEnabled;
{
    int			len;
    register int 	n = 0;
    register unsigned char *ptr;
    register HOST	*host;
    int			nHosts = 0;

    *pEnabled = AccessEnabled ? EnableAccess : DisableAccess;
    for (host = validhosts; host; host = host->next)
    {
	nHosts++;
	n += (((host->len + 3) >> 2) << 2) + sizeof(xHostEntry);
    }
    if (n)
    {
        *data = ptr = (pointer) xalloc (n);
	if (!ptr)
	{
	    return(BadAlloc);
	}
        for (host = validhosts; host; host = host->next)
	{
	    len = host->len;
	    ((xHostEntry *)ptr)->family = host->family;
	    ((xHostEntry *)ptr)->length = len;
	    ptr += sizeof(xHostEntry);
	    acopy (host->addr, ptr, len);
	    ptr += ((len + 3) >> 2) << 2;
        }
    } else {
	*data = NULL;
    }
    *pnHosts = nHosts;
    *pLen = n;
    return(Success);
}

/* Check for valid address family and length, and return address length. */

/*ARGSUSED*/
static int
CheckAddr (family, pAddr, length)
    int			family;
    pointer		pAddr;
    unsigned		length;
{
    int	len;

    switch (family)
    {
#ifdef TCPCONN
      case FamilyInternet:
	if (length == sizeof (struct in_addr))
	    len = length;
	else
	    len = -1;
        break;
#endif 
#ifdef DNETCONN
      case FamilyDECnet:
        {
	    struct dn_naddr *dnaddr = (struct dn_naddr *) pAddr;

	    if ((length < sizeof(dnaddr->a_len)) ||
		(length < dnaddr->a_len + sizeof(dnaddr->a_len)))
		len = -1;
	    else
		len = dnaddr->a_len + sizeof(dnaddr->a_len);
	    if (len > sizeof(struct dn_naddr))
		len = -1;
	}
        break;
#endif
      default:
        len = -1;
    }
    return (len);
}

/* Check if a host is not in the access control list. 
 * Returns 1 if host is invalid, 0 if we've found it. */

InvalidHost (saddr, len)
    register struct sockaddr	*saddr;
    int				len;
{
    int 			family;
    pointer			addr;
    register HOST 		*selfhost, *host;

    if (!AccessEnabled)   /* just let them in */
        return(0);    
    family = ConvertAddr (saddr, &len, (pointer *)&addr);
    if (family == -1)
        return 1;
    if (family == FamilyLocal)
    {
	if (!LocalHostEnabled)
 	{
	    /*
	     * check to see if any local address is enabled.  This 
	     * implicitly enables local connections.
	     */
	    for (selfhost = selfhosts; selfhost; selfhost=selfhost->next)
 	    {
		for (host = validhosts; host; host=host->next)
		{
		    if (addrEqual (selfhost->family, selfhost->addr,
				   selfhost->len, host))
			return 0;
		}
	    }
	    return 1;
	} else
	    return 0;
    }
    for (host = validhosts; host; host = host->next)
    {
        if (addrEqual (family, addr, len, host))
    	    return (0);
    }
    return (1);
}

static int
ConvertAddr (saddr, len, addr)
    register struct sockaddr	*saddr;
    int				*len;
    pointer			*addr;
{
    if (*len == 0)
        return (FamilyLocal);
    switch (saddr->sa_family)
    {
    case AF_UNSPEC:
#ifdef UNIXCONN
    case AF_UNIX:
#endif
        return FamilyLocal;
#ifdef TCPCONN
    case AF_INET:
        *len = sizeof (struct in_addr);
        *addr = (pointer) &(((struct sockaddr_in *) saddr)->sin_addr);
        return FamilyInternet;
#endif
#ifdef DNETCONN
    case AF_DECnet:
	{
	    struct sockaddr_dn *sdn = (struct sockaddr_dn *) saddr;
	    *len = sdn->sdn_nodeaddrl + sizeof(sdn->sdn_nodeaddrl);
	    *addr = (pointer) &(sdn->sdn_add);
	}
        return FamilyDECnet;
#endif
#ifdef CHAOSCONN
    case AF_CHAOS:
	{
	    not implemented
	}
	return FamilyChaos;
#endif
    default:
        return -1;
    }
}

int
ChangeAccessControl(client, fEnabled)
    ClientPtr client;
    int fEnabled;
{
    if (!AuthorizedClient(client))
	return BadAccess;
    AccessEnabled = fEnabled;
    return Success;
}
