xref: /xsrc/external/mit/xhost/dist/xhost.c

/* $Xorg: xhost.c,v 1.4 2001/02/09 02:05:46 xorgcvs Exp $ */
/* $XdotOrg: app/xhost/xhost.c,v 1.4 2005/06/18 08:03:35 alanc Exp $ */
/*

Copyright 1985, 1986, 1987, 1998  The Open Group
Copyright 2004 Sun Microsystems, Inc.

All rights reserved.

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, and/or sell copies of the Software, and to permit persons
to whom the Software is furnished to do so, provided that the above
copyright notice(s) and this permission notice appear in all copies of
the Software and that both the above copyright notice(s) and this
permission notice appear in supporting documentation.

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
OF THIRD PARTY RIGHTS. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
HOLDERS INCLUDED IN THIS NOTICE BE LIABLE FOR ANY CLAIM, OR 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.

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

X Window System is a trademark of The Open Group.

*/
/* $XFree86: xc/programs/xhost/xhost.c,v 3.26 2003/07/27 14:05:45 herrb Exp $ */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#if defined(TCPCONN) || defined(STREAMSCONN)
#define NEEDSOCKETS
#endif
#ifdef UNIXCONN
#define NEEDSOCKETS
#endif
#ifdef DNETCONN
#define NEEDSOCKETS
#endif

#include <X11/Xlib.h>
#include <X11/Xos.h>
#include <X11/Xproto.h>
#include <X11/Xfuncs.h>
#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
#ifdef X_NOT_POSIX
#include <setjmp.h>
#endif
#include <ctype.h>
#include <X11/Xauth.h>
#include <X11/Xmu/Error.h>
#include <stdlib.h>

#ifdef NEEDSOCKETS
#ifdef att
typedef unsigned short unsign16;
typedef unsigned long unsign32;
typedef short sign16;
typedef long sign32;
#include <interlan/socket.h>
#include <interlan/netdb.h>
#include <interlan/in.h>
#else
#ifndef Lynx
#include <sys/socket.h>
#else
#include <socket.h>
#endif
#include <netdb.h>
#include <netinet/in.h>
#endif
#endif /* NEEDSOCKETS */

#ifndef BAD_ARPAINET
#include <arpa/inet.h>
#else
/* bogus definition of inet_makeaddr() in BSD 4.2 and Ultrix */
extern unsigned long inet_makeaddr();
#endif

#ifdef DNETCONN
#include <netdnet/dn.h>
#include <netdnet/dnetdb.h>
#endif

#ifdef SECURE_RPC
#include <pwd.h>
#include <rpc/rpc.h>
#ifdef X_POSIX_C_SOURCE
#define _POSIX_C_SOURCE X_POSIX_C_SOURCE
#include <limits.h>
#undef _POSIX_C_SOURCE
#else
#if defined(X_NOT_POSIX) || defined(_POSIX_SOURCE)
#include <limits.h>
#else
#define _POSIX_SOURCE
#include <limits.h>
#undef _POSIX_SOURCE
#endif
#endif
#ifndef NGROUPS_MAX
#include <sys/param.h>
#define NGROUPS_MAX NGROUPS
#endif
#ifdef sun
/* Go figure, there's no getdomainname() prototype available */
extern int getdomainname(char *name, size_t len);
#endif
#endif

static int change_host(Display *dpy, char *name, Bool add);
static char *get_hostname(XHostAddress *ha);
static int local_xerror(Display *dpy, XErrorEvent *rep);

#ifdef RETSIGTYPE /* autoconf AC_TYPE_SIGNAL */
# define signal_t RETSIGTYPE
#else /* Imake */
#ifdef SIGNALRETURNSINT
#define signal_t int
#else
#define signal_t void
#endif
#endif /* RETSIGTYPE */
static signal_t nameserver_lost(int sig);

#define NAMESERVER_TIMEOUT 5	/* time to wait for nameserver */

static volatile int nameserver_timedout;

static char *ProgramName;

#ifdef NEEDSOCKETS
static int
XFamily(int af)
{
    int i;
    static struct _familyMap {
	int af, xf;
    } familyMap[] = {
#ifdef	AF_DECnet
        { AF_DECnet, FamilyDECnet },
#endif
#ifdef	AF_CHAOS
        { AF_CHAOS, FamilyChaos },
#endif
#ifdef	AF_INET
        { AF_INET, FamilyInternet },
#if defined(IPv6) && defined(AF_INET6)
        { AF_INET6, FamilyInternet6 },
#endif
#endif
};

#define FAMILIES ((sizeof familyMap)/(sizeof familyMap[0]))

    for (i = 0; i < FAMILIES; i++)
	if (familyMap[i].af == af) return familyMap[i].xf;
    return -1;
}
#endif /* NEEDSOCKETS */

static Display *dpy;

int
main(int argc, char *argv[])
{
    register char *arg;
    int i, nhosts = 0;
    char *hostname;
    int nfailed = 0;
    XHostAddress *list;
    Bool enabled = False;
#ifdef DNETCONN
    char *dnet_htoa();
    struct nodeent *np;
    struct dn_naddr *nlist, dnaddr, *dnaddrp, *dnet_addr();
    char *cp;
#endif

    ProgramName = argv[0];

    if ((dpy = XOpenDisplay(NULL)) == NULL) {
	fprintf(stderr, "%s:  unable to open display \"%s\"\n",
		ProgramName, XDisplayName (NULL));
	exit(1);
    }

    XSetErrorHandler(local_xerror);


    if (argc == 1) {
#ifdef DNETCONN
	setnodeent(1);		/* keep the database accessed */
#endif
	sethostent(1);		/* don't close the data base each time */
	list = XListHosts(dpy, &nhosts, &enabled);
	if (enabled)
	    printf ("access control enabled, only authorized clients can connect\n");
	else
	    printf ("access control disabled, clients can connect from any host\n");

	if (nhosts != 0) {
	    for (i = 0; i < nhosts; i++ )  {
		hostname = get_hostname(&list[i]);
		if (hostname) {
		    switch (list[i].family) {
		    case FamilyInternet:
			printf("INET:");
			break;
		    case FamilyInternet6:
			printf("INET6:");
			break;
		    case FamilyDECnet:
			printf("DNET:");
			break;
		    case FamilyNetname:
			printf("NIS:");
			break;
		    case FamilyKrb5Principal:
			printf("KRB:");
			break;
		    case FamilyLocalHost:
			printf("LOCAL:");
			break;
		    case FamilyServerInterpreted:
			printf("SI:");
			break;
		    default:
			printf("<unknown family type %d>:", list[i].family);
			break;
		    }
		    printf ("%s", hostname);
		} else {
		    printf ("<unknown address in family %d>",
			    list[i].family);
		}
		if (nameserver_timedout) {
		    printf("\t(no nameserver response within %d seconds)\n",
			   NAMESERVER_TIMEOUT);
		    nameserver_timedout = 0;
		} else
		    printf("\n");
	    }
	    free(list);
	    endhostent();
	}
	exit(0);
    }

    if (argc == 2 && !strcmp(argv[1], "-help")) {
	fprintf(stderr, "usage: %s [[+-]hostname ...]\n", argv[0]);
	exit(1);
    }

    for (i = 1; i < argc; i++) {
	arg = argv[i];
	if (*arg == '-') {

	    if (!argv[i][1] && ((i+1) == argc)) {
		printf ("access control enabled, only authorized clients can connect\n");
		XEnableAccessControl(dpy);
	    } else {
		arg = argv[i][1]? &argv[i][1] : argv[++i];
		if (!change_host (dpy, arg, False)) {
		    fprintf (stderr, "%s:  bad hostname \"%s\"\n",
			     ProgramName, arg);
		    nfailed++;
		}
	    }
	} else {
	    if (*arg == '+' && !argv[i][1] && ((i+1) == argc)) {
		printf ("access control disabled, clients can connect from any host\n");
		XDisableAccessControl(dpy);
	    } else {
		if (*arg == '+') {
		    arg = argv[i][1]? &argv[i][1] : argv[++i];
		}
		if (!change_host (dpy, arg, True)) {
		    fprintf (stderr, "%s:  bad hostname \"%s\"\n",
			     ProgramName, arg);
		    nfailed++;
		}
	    }
	}
    }
    XCloseDisplay (dpy);	/* does an XSync first */
    exit(nfailed);
}



/*
 * change_host - edit the list of hosts that may connect to the server;
 * it parses DECnet names (expo::), Internet addresses (18.30.0.212), or
 * Internet names (expo.lcs.mit.edu); if 4.3bsd macro h_addr is defined
 * (from <netdb.h>), it will add or remove all addresses with the given
 * address.
 */

static int
change_host(Display *dpy, char *name, Bool add)
{
    XHostAddress ha;
    char *lname;
    int namelen, i, family = FamilyWild;
#ifdef K5AUTH
    krb5_principal princ;
    krb5_data kbuf;
#endif
#ifdef NEEDSOCKETS
    static struct in_addr addr;	/* so we can point at it */
#if defined(IPv6) && defined(AF_INET6)
    static struct in6_addr addr6; /* so we can point at it */
#else
    struct hostent *hp;
#endif
#endif
    char *cp;
#ifdef DNETCONN
    struct dn_naddr *dnaddrp;
    struct nodeent *np;
    static struct dn_naddr dnaddr;
#endif				/* DNETCONN */
    static char *add_msg = "being added to access control list";
    static char *remove_msg = "being removed from access control list";

    namelen = strlen(name);
    if ((lname = (char *)malloc(namelen+1)) == NULL) {
	fprintf (stderr, "%s: malloc bombed in change_host\n", ProgramName);
	exit (1);
    }
    for (i = 0; i < namelen; i++) {
	lname[i] = tolower(name[i]);
    }
    lname[namelen] = '\0';
    if (!strncmp("inet:", lname, 5)) {
#if defined(TCPCONN) || defined(STREAMSCONN)
	family = FamilyInternet;
	name += 5;
#else
	fprintf (stderr, "%s: not compiled for TCP/IP\n", ProgramName);
	free(lname);
	return 0;
#endif
    }
    else if (!strncmp("inet6:", lname, 6)) {
#if (defined(TCPCONN) || defined(STREAMSCONN)) && \
    defined(IPv6) && defined(AF_INET6)
	family = FamilyInternet6;
	name += 6;
#else
	fprintf (stderr, "%s: not compiled for IPv6\n", ProgramName);
	free(lname);
	return 0;
#endif
    }
#ifdef ACCEPT_INETV6 /* Allow inetv6 as an alias for inet6 for compatibility
			with original X11 over IPv6 draft. */
    else if (!strncmp("inetv6:", lname, 7)) {
#if (defined(TCPCONN) || defined(STREAMSCONN)) && \
    defined(IPv6) && defined(AF_INET6)
	family = FamilyInternet6;
	name += 7;
#else
	fprintf (stderr, "%s: not compiled for IPv6\n", ProgramName);
	free(lname);
	return 0;
#endif
    }
#endif /* ACCEPT_INETV6 */
    else if (!strncmp("dnet:", lname, 5)) {
#ifdef DNETCONN
	family = FamilyDECnet;
	name += 5;
#else
	fprintf (stderr, "%s: not compiled for DECnet\n", ProgramName);
	free(lname);
	return 0;
#endif
    }
    else if (!strncmp("nis:", lname, 4)) {
#ifdef SECURE_RPC
	family = FamilyNetname;
	name += 4;
#else
	fprintf (stderr, "%s: not compiled for Secure RPC\n", ProgramName);
	free(lname);
	return 0;
#endif
    }
    else if (!strncmp("krb:", lname, 4)) {
#ifdef K5AUTH
	family = FamilyKrb5Principal;
	name +=4;
#else
	fprintf (stderr, "%s: not compiled for Kerberos 5\n", ProgramName);
	free(lname);
	return 0;
#endif
    }
    else if (!strncmp("local:", lname, 6)) {
	family = FamilyLocalHost;
    }
    else if (!strncmp("si:", lname, 3)) {
	family = FamilyServerInterpreted;
	name += 3;
    }
    if (family == FamilyWild && (cp = strchr(lname, ':'))) {
	*cp = '\0';
	fprintf (stderr, "%s: unknown address family \"%s\"\n",
		 ProgramName, lname);
	free(lname);
	return 0;
    }
    free(lname);

    if (family == FamilyServerInterpreted) {
	XServerInterpretedAddress siaddr;
	int namelen;

	cp = strchr(name, ':');
	if (cp == NULL || cp == name) {
	    fprintf(stderr,
	   "%s: type must be specified for server interpreted family \"%s\"\n",
	      ProgramName, name);
	    return 0;
	}
	ha.family = FamilyServerInterpreted;
	ha.address = (char *) &siaddr;
	namelen = strlen(name);
	siaddr.type = malloc(namelen);
	if (siaddr.type == NULL) {
	    return 0;
	}
	memcpy(siaddr.type, name, namelen);
	siaddr.typelength = cp - name;
	siaddr.type[siaddr.typelength] = '\0';
	siaddr.value = siaddr.type + siaddr.typelength + 1;
	siaddr.valuelength = namelen - (siaddr.typelength + 1);
	if (add)
	    XAddHost(dpy, &ha);
	else
	    XRemoveHost(dpy, &ha);
	free(siaddr.type);
	printf( "%s %s\n", name, add ? add_msg : remove_msg);
	return 1;
    }

#ifdef DNETCONN
    if (family == FamilyDECnet || ((family == FamilyWild) &&
	(cp = strchr(name, ':')) && (*(cp + 1) == ':') &&
	!(*cp = '\0'))) {
	ha.family = FamilyDECnet;
	if (dnaddrp = dnet_addr(name)) {
	    dnaddr = *dnaddrp;
	} else {
	    if ((np = getnodebyname (name)) == NULL) {
		fprintf (stderr, "%s:  unable to get node name for \"%s::\"\n",
			 ProgramName, name);
		return 0;
	    }
	    dnaddr.a_len = np->n_length;
	    memmove( dnaddr.a_addr, np->n_addr, np->n_length);
	}
	ha.length = sizeof(struct dn_naddr);
	ha.address = (char *)&dnaddr;
	if (add) {
	    XAddHost (dpy, &ha);
	    printf ("%s:: %s\n", name, add_msg);
	} else {
	    XRemoveHost (dpy, &ha);
	    printf ("%s:: %s\n", name, remove_msg);
	}
	return 1;
    }
#endif				/* DNETCONN */
#ifdef K5AUTH
    if (family == FamilyKrb5Principal) {
	krb5_error_code retval;

	retval = krb5_parse_name(name, &princ);
	if (retval) {
	    krb5_init_ets();	/* init krb errs for error_message() */
	    fprintf(stderr, "%s: cannot parse Kerberos name: %s\n",
		    ProgramName, error_message(retval));
	    return 0;
	}
	XauKrb5Encode(princ, &kbuf);
	ha.length = kbuf.length;
	ha.address = kbuf.data;
	ha.family = family;
	if (add)
	    XAddHost(dpy, &ha);
	else
	    XRemoveHost(dpy, &ha);
	krb5_free_principal(princ);
	free(kbuf.data);
	printf( "%s %s\n", name, add ? add_msg : remove_msg);
	return 1;
    }
#endif
    if (family == FamilyLocalHost) {
	ha.length = 0;
	ha.address = "";
	ha.family = family;
	if (add)
	    XAddHost(dpy, &ha);
	else
	    XRemoveHost(dpy, &ha);
	printf( "non-network local connections %s\n", add ? add_msg : remove_msg);
	return 1;
    }
    /*
     * If it has an '@', it's a netname
     */
    if ((family == FamilyNetname && (cp = strchr(name, '@'))) ||
	(cp = strchr(name, '@'))) {
        char *netname = name;
#ifdef SECURE_RPC
	static char username[MAXNETNAMELEN];

	if (!cp[1]) {
	    struct passwd *pwd;
	    static char domainname[128];

	    *cp = '\0';
	    pwd = getpwnam(name);
	    if (!pwd) {
		fprintf(stderr, "no such user \"%s\"\n", name);
		return 0;
	    }
	    getdomainname(domainname, sizeof(domainname));
	    if (!user2netname(username, pwd->pw_uid, domainname)) {
		fprintf(stderr, "failed to get netname for \"%s\"\n", name);
		return 0;
	    }
	    netname = username;
	}
#endif
	ha.family = FamilyNetname;
	ha.length = strlen(netname);
	ha.address = netname;
	if (add)
	    XAddHost (dpy, &ha);
	else
	    XRemoveHost (dpy, &ha);
	if (netname != name)
	    printf ("%s@ (%s) %s\n", name, netname, add ? add_msg : remove_msg);
	else
	    printf ("%s %s\n", netname, add ? add_msg : remove_msg);
        return 1;
    }
#ifdef NEEDSOCKETS
    /*
     * First see if inet_addr() can grok the name; if so, then use it.
     */
    if (((family == FamilyWild) || (family == FamilyInternet)) &&
	((addr.s_addr = inet_addr(name)) != -1)) {
	ha.family = FamilyInternet;
	ha.length = 4;		/* but for Cray would be sizeof(addr.s_addr) */
	ha.address = (char *)&addr; /* but for Cray would be &addr.s_addr */
	if (add) {
	    XAddHost (dpy, &ha);
	    printf ("%s %s\n", name, add_msg);
	} else {
	    XRemoveHost (dpy, &ha);
	    printf ("%s %s\n", name, remove_msg);
	}
	return 1;
    }
#if defined(IPv6) && defined(AF_INET6)
    /*
     * Check to see if inet_pton() can grok it as an IPv6 address
     */
    else if (((family == FamilyWild) || (family == FamilyInternet6)) &&
	     (inet_pton(AF_INET6, name, &addr6.s6_addr) == 1)) {
	ha.family = FamilyInternet6;
	ha.length = sizeof(addr6.s6_addr);
	ha.address = (char *) &addr6.s6_addr;
	if (add) {
	    XAddHost (dpy, &ha);
	    printf ("%s %s\n", name, add_msg);
	} else {
	    XRemoveHost (dpy, &ha);
	    printf ("%s %s\n", name, remove_msg);
	}
	return 1;
    } else {
    /*
     * Is it in the namespace?
     *
     * If no family was specified, use both Internet v4 & v6 addresses.
     * Otherwise, use only addresses matching specified family.
     */
	struct addrinfo *addresses;
	struct addrinfo *a;
	Bool didit = False;

	if (getaddrinfo(name, NULL, NULL, &addresses) != 0)
	    return 0;

	for (a = addresses; a != NULL; a = a->ai_next) {
	    if ( ((a->ai_family == AF_INET) && (family != FamilyInternet6))
	      || ((a->ai_family == AF_INET6) && (family != FamilyInternet)) ) {
		char ad[INET6_ADDRSTRLEN];
		ha.family = XFamily(a->ai_family);
		if (a->ai_family == AF_INET6) {
		    ha.address = (char *)
		      &((struct sockaddr_in6 *) a->ai_addr)->sin6_addr;
		    ha.length =
		      sizeof (((struct sockaddr_in6 *) a->ai_addr)->sin6_addr);
		} else {
		    ha.address = (char *)
		      &((struct sockaddr_in *) a->ai_addr)->sin_addr;
		    ha.length =
		      sizeof (((struct sockaddr_in *) a->ai_addr)->sin_addr);
		}
		inet_ntop(a->ai_family, ha.address, ad, sizeof(ad));
	/* printf("Family: %d\nLength: %d\n", a->ai_family, ha.length); */
		/* printf("Address: %s\n", ad); */

		if (add) {
		    XAddHost (dpy, &ha);
		} else {
		    XRemoveHost (dpy, &ha);
		}
		didit = True;
	    }
	}
	if (didit == True) {
	    printf ("%s %s\n", name, add ? add_msg : remove_msg);
	} else {
	    const char *familyMsg = "";

	    if (family == FamilyInternet6) {
		familyMsg = "inet6 ";
	    } else if (family == FamilyInternet) {
		familyMsg = "inet ";
	    }

	    fprintf(stderr, "%s: unable to get %saddress for \"%s\"\n",
		ProgramName, familyMsg, name);
	}
	freeaddrinfo(addresses);
	return 1;
    }
#else /* !IPv6 */
    /*
     * Is it in the namespace?
     */
    else if (((hp = gethostbyname(name)) == (struct hostent *)NULL)
	     || hp->h_addrtype != AF_INET) {
	return 0;
    } else {
	ha.family = XFamily(hp->h_addrtype);
	ha.length = hp->h_length;
#ifdef h_addr			/* new 4.3bsd version of gethostent */
    {
	char **list;

	/* iterate over the hosts */
	for (list = hp->h_addr_list; *list; list++) {
	    ha.address = *list;
	    if (add) {
		XAddHost (dpy, &ha);
	    } else {
		XRemoveHost (dpy, &ha);
	    }
	}
    }
#else
	ha.address = hp->h_addr;
	if (add) {
	    XAddHost (dpy, &ha);
	} else {
	    XRemoveHost (dpy, &ha);
	}
#endif
	printf ("%s %s\n", name, add ? add_msg : remove_msg);
	return 1;
    }
#endif /* IPv6 */
#else /* NEEDSOCKETS */
    return 0;
#endif /* NEEDSOCKETS */
}


/*
 * get_hostname - Given an internet address, return a name (CHARON.MIT.EDU)
 * or a string representing the address (18.58.0.13) if the name cannot
 * be found.
 */

#ifdef X_NOT_POSIX
jmp_buf env;
#endif

static char *
get_hostname(XHostAddress *ha)
{
#if (defined(TCPCONN) || defined(STREAMSCONN)) &&	\
     (!defined(IPv6) || !defined(AF_INET6))
    static struct hostent *hp = NULL;
#endif
#ifdef DNETCONN
    struct nodeent *np;
    static char nodeaddr[5 + 2 * DN_MAXADDL];
#endif				/* DNETCONN */
#ifdef K5AUTH
    krb5_principal princ;
    krb5_data kbuf;
    char *kname;
    static char kname_out[255];
#endif
#ifndef X_NOT_POSIX
    struct sigaction sa;
#endif

#if defined(TCPCONN) || defined(STREAMSCONN)
#if defined(IPv6) && defined(AF_INET6)
    if ((ha->family == FamilyInternet) || (ha->family == FamilyInternet6)) {
	struct sockaddr_storage saddr;
	static char inetname[NI_MAXHOST];
	int saddrlen;

	inetname[0] = '\0';
	memset(&saddr, 0, sizeof saddr);
	if (ha->family == FamilyInternet) {
	    struct sockaddr_in *sin = (struct sockaddr_in *) &saddr;
#ifdef BSD44SOCKETS
	    sin->sin_len = sizeof(struct sockaddr_in);
#endif
	    sin->sin_family = AF_INET;
	    sin->sin_port = 0;
	    memcpy(&sin->sin_addr, ha->address, sizeof(sin->sin_addr));
	    saddrlen = sizeof(struct sockaddr_in);
	} else {
	    struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *) &saddr;
#ifdef SIN6_LEN
	    sin6->sin6_len = sizeof(struct sockaddr_in6);
#endif
	    sin6->sin6_family = AF_INET6;
	    sin6->sin6_port = 0;
	    memcpy(&sin6->sin6_addr, ha->address, sizeof(sin6->sin6_addr));
	    saddrlen = sizeof(struct sockaddr_in6);
	}

	/* gethostbyaddr can take a LONG time if the host does not exist.
	   Assume that if it does not respond in NAMESERVER_TIMEOUT seconds
	   that something is wrong and do not make the user wait.
	   gethostbyaddr will continue after a signal, so we have to
	   jump out of it.
	   */
#ifndef X_NOT_POSIX
	memset(&sa, 0, sizeof sa);
	sa.sa_handler = nameserver_lost;
	sa.sa_flags = 0;	/* don't restart syscalls */
	sigaction(SIGALRM, &sa, NULL);
#else
	signal(SIGALRM, nameserver_lost);
#endif
	alarm(NAMESERVER_TIMEOUT);
#ifdef X_NOT_POSIX
	if (setjmp(env) == 0)
#endif
	{
	    getnameinfo((struct sockaddr *) &saddr, saddrlen, inetname,
	      sizeof(inetname), NULL, 0, 0);
	}
	alarm(0);
	if (nameserver_timedout || inetname[0] == '\0')
	    inet_ntop(((struct sockaddr *)&saddr)->sa_family, ha->address,
		inetname, sizeof(inetname));
	return inetname;
    }
#else
    if (ha->family == FamilyInternet) {
#ifdef CRAY
	struct in_addr t_addr;
	bzero((char *)&t_addr, sizeof(t_addr));
	bcopy(ha->address, (char *)&t_addr, 4);
	ha->address = (char *)&t_addr;
#endif
	/* gethostbyaddr can take a LONG time if the host does not exist.
	   Assume that if it does not respond in NAMESERVER_TIMEOUT seconds
	   that something is wrong and do not make the user wait.
	   gethostbyaddr will continue after a signal, so we have to
	   jump out of it.
	   */
#ifndef X_NOT_POSIX
	memset(&sa, 0, sizeof sa);
	sa.sa_handler = nameserver_lost;
	sa.sa_flags = 0;	/* don't restart syscalls */
	sigaction(SIGALRM, &sa, NULL);
#else
	signal(SIGALRM, nameserver_lost);
#endif
	alarm(4);
#ifdef X_NOT_POSIX
	if (setjmp(env) == 0) {
#endif
	    hp = gethostbyaddr (ha->address, ha->length, AF_INET);
#ifdef X_NOT_POSIX
	}
#endif
	alarm(0);
	if (hp)
	    return (hp->h_name);
	else return (inet_ntoa(*((struct in_addr *)(ha->address))));
    }
#endif /* IPv6 */
#endif
    if (ha->family == FamilyNetname) {
	static char netname[512];
	int len;
#ifdef SECURE_RPC
	int gidlen;
	uid_t uid;
	gid_t gid, gidlist[NGROUPS_MAX];
#endif

	if (ha->length < sizeof(netname) - 1)
	    len = ha->length;
	else
	    len = sizeof(netname) - 1;
	memmove( netname, ha->address, len);
	netname[len] = '\0';
#ifdef SECURE_RPC
	if (netname2user(netname, &uid, &gid, &gidlen, gidlist)) {
	    struct passwd *pwd;

	    pwd = getpwuid(uid);
	    if (pwd)
		sprintf(netname, "%s@ (%*.*s)", pwd->pw_name,
			ha->length, ha->length, ha->address);
	}
#endif
	return (netname);
    }
#ifdef DNETCONN
    if (ha->family == FamilyDECnet) {
	struct dn_naddr *addr_ptr = (struct dn_naddr *) ha->address;

	if (np = getnodebyaddr(addr_ptr->a_addr, addr_ptr->a_len, AF_DECnet)) {
	    sprintf(nodeaddr, "%s", np->n_name);
	} else {
	    sprintf(nodeaddr, "%s", dnet_htoa(ha->address));
	}
	return(nodeaddr);
    }
#endif
#ifdef K5AUTH
    if (ha->family == FamilyKrb5Principal) {
	kbuf.data = ha->address;
	kbuf.length = ha->length;
	XauKrb5Decode(kbuf, &princ);
	krb5_unparse_name(princ, &kname);
	krb5_free_principal(princ);
	strncpy(kname_out, kname, sizeof (kname_out));
	free(kname);
	return kname_out;
    }
#endif
    if (ha->family == FamilyLocalHost) {
	return "";
    }
    if (ha->family == FamilyServerInterpreted) {
	XServerInterpretedAddress *sip;
	static char *addressString;
	static size_t addressStringSize;
	size_t neededSize;

	sip = (XServerInterpretedAddress *) ha->address;
	neededSize = sip->typelength + sip->valuelength + 2;

	if (addressStringSize < neededSize) {
	    if (addressString != NULL) {
		free(addressString);
	    }
	    addressStringSize = neededSize;
	    addressString = malloc(addressStringSize);
	}
	if (addressString != NULL) {
	    char *cp = addressString;

	    memcpy(cp, sip->type, sip->typelength);
	    cp += sip->typelength;
	    *cp++ = ':';
	    memcpy(cp, sip->value, sip->valuelength);
	    cp += sip->valuelength;
	    *cp = '\0';
	}
	return addressString;
    }
    return (NULL);
}

/*ARGUSED*/
static signal_t
nameserver_lost(int sig)
{
    nameserver_timedout = 1;
#ifdef X_NOT_POSIX
    /* not needed with POSIX signals - stuck syscalls will not
       be restarted after signal delivery */
    longjmp(env, -1);
#endif
}

/*
 * local_xerror - local non-fatal error handling routine. If the error was
 * that an X_GetHosts request for an unknown address format was received, just
 * return, otherwise print the normal error message and continue.
 */
static int
local_xerror(Display *dpy, XErrorEvent *rep)
{
    if ((rep->error_code == BadAccess) && (rep->request_code == X_ChangeHosts)) {
	fprintf (stderr,
		 "%s:  must be on local machine to add or remove hosts.\n",
		 ProgramName);
	return 1;
    } else if ((rep->error_code == BadAccess) &&
	       (rep->request_code == X_SetAccessControl)) {
	fprintf (stderr,
	"%s:  must be on local machine to enable or disable access control.\n",
		 ProgramName);
	return 1;
    } else if ((rep->error_code == BadValue) &&
	       (rep->request_code == X_ListHosts)) {
	return 1;
    }

    XmuPrintDefaultErrorMessage (dpy, rep, stderr);
    return 0;
}

#ifdef __CYGWIN__
void sethostent(int x)
{}

void endhostent()
{}
#endif