NetBSD/usr.sbin/named/nslookup/main.c

/*	$NetBSD: main.c,v 1.4 1998/10/15 12:34:21 drochner Exp $	*/

/*
 * ++Copyright++ 1985, 1989
 * -
 * Copyright (c) 1985, 1989
 *    The Regents of the University of California.  All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 * 	This product includes software developed by the University of
 * 	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * -
 * Portions Copyright (c) 1993 by Digital Equipment Corporation.
 * 
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies, and that
 * the name of Digital Equipment Corporation not be used in advertising or
 * publicity pertaining to distribution of the document or software without
 * specific, written prior permission.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
 * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS.   IN NO EVENT SHALL DIGITAL EQUIPMENT
 * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, 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.
 * -
 * --Copyright--
 */

#ifndef lint
char copyright[] =
"@(#) Copyright (c) 1985,1989 Regents of the University of California.\n\
 All rights reserved.\n";
#endif /* not lint */

#ifndef lint
static char sccsid[] = "@(#)main.c	5.42 (Berkeley) 3/3/91";
static char rcsid[] = "$Id: main.c,v 1.4 1998/10/15 12:34:21 drochner Exp $";
#endif /* not lint */

/*
 ******************************************************************************
 *  
 *   main.c --
 *  
 *	Main routine and some action routines for the name server
 *	lookup program.
 *
 *	Andrew Cherenson
 *	U.C. Berkeley Computer Science Div.
 *	CS298-26, Fall 1985
 *  
 ******************************************************************************
 */

#include <sys/param.h>
#include <netdb.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/nameser.h>
#include <arpa/inet.h>
#include <resolv.h>
#include <signal.h>
#include <setjmp.h>
#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <limits.h>
#include "res.h"
#include "pathnames.h"


/*
 * Name of a top-level name server. Can be changed with 
 * the "set root" command.
 */

#ifndef ROOT_SERVER
#define		ROOT_SERVER "a.root-servers.net."
#endif
char		rootServerName[NAME_LEN] = ROOT_SERVER;


/*
 *  Import the state information from the resolver library.
 */

extern struct __res_state _res;


/*
 *  Info about the most recently queried host.
 */

HostInfo	curHostInfo;
int		curHostValid = FALSE;


/*
 *  Info about the default name server.
 */

HostInfo	*defaultPtr = NULL;
char		defaultServer[NAME_LEN];
struct in_addr	defaultAddr;


/*
 *  Initial name server query type is Address.
 */

int		queryType = T_A;
int		queryClass = C_IN;

/*
 * Stuff for Interrupt (control-C) signal handler.
 */

extern void	IntrHandler();
FILE		*filePtr;
jmp_buf		env;


/*
 * Browser command for help and view.
 */
char		*pager;

static void CvtAddrToPtr();
static void ReadRC();


/*
 ******************************************************************************
 *
 *  main --
 *
 *	Initializes the resolver library and determines the address
 *	of the initial name server. The yylex routine is used to
 *	read and perform commands.
 *
 ******************************************************************************
 */

main(argc, argv)
    int		argc;
    char	**argv;
{
    char	*wantedHost = NULL;
    Boolean	useLocalServer;
    int		result;
    int		i;
    struct hostent	*hp;

    /*
     *  Initialize the resolver library routines.
     */

    if (res_init() == -1) {
	fprintf(stderr,"*** Can't initialize resolver.\n");
	exit(1);
    }

    /*
     *  Allocate space for the default server's host info and
     *  find the server's address and name. If the resolver library
     *  already has some addresses for a potential name server,
     *  then use them. Otherwise, see if the current host has a server.
     *  Command line arguments may override the choice of initial server. 
     */

    defaultPtr = (HostInfo *) Calloc(1, sizeof(HostInfo));

    /*
     * Parse the arguments:
     *  no args =  go into interactive mode, use default host as server
     *	1 arg	=  use as host name to be looked up, default host will be server
     *		   non-interactive mode
     *  2 args	=  1st arg: 
     *		     if it is '-', then 
     *		        ignore but go into interactive mode
     *		     else 
     *		         use as host name to be looked up, 
     *			 go into non-interactive mode
     *		2nd arg: name or inet address of server
     *
     *	"Set" options are specified with a leading - and must come before
     *	any arguments. For example, to find the well-known services for
     *  a host, type "nslookup -query=wks host"
     */

    ReadRC();			/* look for options file */

    ++argv; --argc;		/* skip prog name */

    while (argc && *argv[0] == '-' && argv[0][1]) {
	(void) SetOption (&(argv[0][1]));
	++argv; --argc;
    }
    if (argc > 2) {
	Usage();
    } 
    if (argc && *argv[0] != '-') {
	wantedHost = *argv;	/* name of host to be looked up */
    }

    useLocalServer = FALSE;
    if (argc == 2) {
	struct in_addr addr;

	/*
	 * Use an explicit name server. If the hostname lookup fails,
	 * default to the server(s) in resolv.conf.
	 */ 

	if (inet_aton(*++argv, &addr)) {
	    _res.nscount = 1;
	    _res.nsaddr.sin_addr = addr;
	} else {
	    hp = gethostbyname(*argv);
	    if (hp == NULL) {
		fprintf(stderr, "*** Can't find server address for '%s': ", 
			*argv);
		herror((char *)NULL);
		fputc('\n', stderr);
	    } else {
		for (i = 0; i < MAXNS && hp->h_addr_list[i] != NULL; i++) {
		    bcopy(hp->h_addr_list[i], 
			    (char *)&_res.nsaddr_list[i].sin_addr, 
			    hp->h_length);
		}
		_res.nscount = i;
	    } 
	}
    }


    if (_res.nscount == 0 || useLocalServer) {
	LocalServer(defaultPtr);
    } else {
	for (i = 0; i < _res.nscount; i++) {
	    if (_res.nsaddr_list[i].sin_addr.s_addr == INADDR_ANY) {
	        LocalServer(defaultPtr);
		break;
	    } else {
		result = GetHostInfoByAddr(&(_res.nsaddr_list[i].sin_addr), 
				    &(_res.nsaddr_list[i].sin_addr), 
				    defaultPtr);
		if (result != SUCCESS) {
		    fprintf(stderr,
		    "*** Can't find server name for address %s: %s\n", 
		       inet_ntoa(_res.nsaddr_list[i].sin_addr), 
		       DecodeError(result));
		} else {
		    defaultAddr = _res.nsaddr_list[i].sin_addr;
		    break;
		}
	    }
	}

	/*
	 *  If we have exhausted the list, tell the user about the
	 *  command line argument to specify an address.
	 */

	if (i == _res.nscount) {
	    fprintf(stderr, "*** Default servers are not available\n");
	    exit(1);
	}

    }
    strcpy(defaultServer, defaultPtr->name);


#ifdef DEBUG
#ifdef DEBUG2
    _res.options |= RES_DEBUG2;
#endif
    _res.options |= RES_DEBUG;
    _res.retry    = 2;
#endif /* DEBUG */

    /*
     * If we're in non-interactive mode, look up the wanted host and quit.
     * Otherwise, print the initial server's name and continue with
     * the initialization.
     */

    if (wantedHost != (char *) NULL) {
	LookupHost(wantedHost, 0);
    } else {
	PrintHostInfo(stdout, "Default Server:", defaultPtr);

	pager = getenv("PAGER");
	if (pager == NULL) {
	    pager = _PATH_PAGERCMD;
	}

	/*
	 * Setup the environment to allow the interrupt handler to return here.
	 */

	(void) setjmp(env);

	/* 
	 * Return here after a longjmp.
	 */

	signal(SIGINT, IntrHandler);
	signal(SIGPIPE, SIG_IGN);

	/*
	 * Read and evaluate commands. The commands are described in commands.l
	 * Yylex returns 0 when ^D or 'exit' is typed. 
	 */

	printf("> ");
	fflush(stdout);
	while(yylex()) {
	    printf("> ");
	    fflush(stdout);
	}
    }
    exit(0);
}


LocalServer(defaultPtr)
    HostInfo *defaultPtr;
{
    char	hostName[NAME_LEN];

    (void) gethostname(hostName, sizeof(hostName));

    defaultAddr.s_addr = htonl(INADDR_ANY);
    (void) GetHostInfoByName(&defaultAddr, C_IN, T_A,
			     "0.0.0.0", defaultPtr, 1);
    free(defaultPtr->name);
    defaultPtr->name = Calloc(1, sizeof(hostName)+1);
    strcpy(defaultPtr->name, hostName);
}


/*
 ******************************************************************************
 *
 *  Usage --
 *
 *	Lists the proper methods to run the program and exits.
 *
 ******************************************************************************
 */

Usage()
{
    fprintf(stderr, "Usage:\n");
    fprintf(stderr,
"   nslookup [-opt ...]             # interactive mode using default server\n");
    fprintf(stderr,
"   nslookup [-opt ...] - server    # interactive mode using 'server'\n");
    fprintf(stderr,
"   nslookup [-opt ...] host        # just look up 'host' using default server\n");
    fprintf(stderr,
"   nslookup [-opt ...] host server # just look up 'host' using 'server'\n");
    exit(1);
}

/*
 ******************************************************************************
 *
 * IsAddr --
 *
 *	Returns TRUE if the string looks like an Internet address.
 *	A string with a trailing dot is not an address, even if it looks
 *	like one.
 *
 ******************************************************************************
 */

Boolean
IsAddr(host, addrPtr)
    char *host;
    struct in_addr *addrPtr;	/* If return TRUE, contains IP address */
{
    register char *cp;

    if (isdigit(host[0])) {
	    /* Make sure it has only digits and dots. */
	    for (cp = host; *cp; ++cp) {
		if (!isdigit(*cp) && *cp != '.') 
		    return FALSE;
	    }
	    /* If it has a trailing dot, don't treat it as an address. */
	    if (*--cp != '.') { 
		return inet_aton(host, addrPtr);
	    }
    }
    return FALSE;
}


/*
 ******************************************************************************
 *
 *  SetDefaultServer --
 *
 *	Changes the default name server to the one specified by
 *	the first argument. The command "server name" uses the current 
 *	default server to lookup the info for "name". The command
 *	"lserver name" uses the original server to lookup "name".
 *
 *  Side effects:
 *	This routine will cause a core dump if the allocation requests fail.
 *
 *  Results:
 *	SUCCESS		The default server was changed successfully.
 *	NONAUTH		The server was changed but addresses of
 *			other servers who know about the requested server
 *			were returned.
 *	Errors		No info about the new server was found or
 *			requests to the current server timed-out.
 *
 ******************************************************************************
 */

int
SetDefaultServer(string, local)
    char	*string;
    Boolean	local;
{
    register HostInfo	*newDefPtr;
    struct in_addr	*servAddrPtr;
    struct in_addr	addr;
    char		newServer[NAME_LEN];
    int			result;
    int			i;

    /*
     *  Parse the command line. It maybe of the form "server name",
     *  "lserver name" or just "name".
     */

    if (local) {
	i = sscanf(string, " lserver %s", newServer);
    } else {
	i = sscanf(string, " server %s", newServer);
    }
    if (i != 1) {
	i = sscanf(string, " %s", newServer);
	if (i != 1) {
	    fprintf(stderr,"SetDefaultServer: invalid name: %s\n",  string);
	    return(ERROR);
	}
    }

    /*
     * Allocate space for a HostInfo variable for the new server. Don't
     * overwrite the old HostInfo struct because info about the new server
     * might not be found and we need to have valid default server info.
     */

    newDefPtr = (HostInfo *) Calloc(1, sizeof(HostInfo));


    /*
     *	A 'local' lookup uses the original server that the program was
     *  initialized with.
     *
     *  Check to see if we have the address of the server or the
     *  address of a server who knows about this domain.
     *  XXX For now, just use the first address in the list.
     */

    if (local) {
	servAddrPtr = &defaultAddr;
    } else if (defaultPtr->addrList != NULL) {
	servAddrPtr = (struct in_addr *) defaultPtr->addrList[0];
    } else {
	servAddrPtr = (struct in_addr *) defaultPtr->servers[0]->addrList[0];
    }

    result = ERROR;
    if (IsAddr(newServer, &addr)) {
	result = GetHostInfoByAddr(servAddrPtr, &addr, newDefPtr);
	/* If we can't get the name, fall through... */
    } 
    if (result != SUCCESS && result != NONAUTH) {
	result = GetHostInfoByName(servAddrPtr, C_IN, T_A, 
			newServer, newDefPtr, 1);
    }

    /* If we ask for an A record and get none back, but get an NS
       record for the NS server, this is the NONAUTH case.
       We must check whether we got an IP address for the NS
       server or not.  */
    if ((result == SUCCESS || result == NONAUTH) &&
	((newDefPtr->addrList && newDefPtr->addrList[0] != 0) || 
	 (newDefPtr->servers && newDefPtr->servers[0] &&
			newDefPtr->servers[0]->addrList[0] != 0))) {
	    /*
	     *  Found info about the new server. Free the resources for
	     *  the old server.
	     */

	    FreeHostInfoPtr(defaultPtr);
	    free((char *)defaultPtr);
	    defaultPtr = newDefPtr;
	    strcpy(defaultServer, defaultPtr->name);
	    PrintHostInfo(stdout, "Default Server:", defaultPtr);
	    return(SUCCESS);
    } else {
	    fprintf(stderr, "*** Can't find address for server %s: %s\n",
		    newServer, DecodeError(result));
	    free((char *)newDefPtr);

	    return(result);
    }
}

/*
 ******************************************************************************
 *
 * DoLoookup --
 *
 *	Common subroutine for LookupHost and LookupHostWithServer.
 *
 *  Results:
 *	SUCCESS		- the lookup was successful.
 *	Misc. Errors	- an error message is printed if the lookup failed.
 *
 ******************************************************************************
 */

static int
DoLookup(host, servPtr, serverName)
    char	*host;
    HostInfo	*servPtr;
    char	*serverName;
{
    int result;
    struct in_addr *servAddrPtr;
    struct in_addr addr; 

    /* Skip escape character */
    if (host[0] == '\\')
	host++;

    /*
     *  If the user gives us an address for an address query, 
     *  silently treat it as a PTR query. If the query type is already
     *  PTR, then convert the address into the in-addr.arpa format.
     *
     *  Use the address of the server if it exists, otherwise use the
     *	address of a server who knows about this domain.
     *  XXX For now, just use the first address in the list.
     */

    if (servPtr->addrList != NULL) {
	servAddrPtr = (struct in_addr *) servPtr->addrList[0];
    } else {
	servAddrPtr = (struct in_addr *) servPtr->servers[0]->addrList[0];
    }

    /* 
     * RFC1123 says we "SHOULD check the string syntactically for a 
     * dotted-decimal number before looking it up [...]" (p. 13).
     */
    if (queryType == T_A && IsAddr(host, &addr)) {
	result = GetHostInfoByAddr(servAddrPtr, &addr, &curHostInfo);
    } else {
	if (queryType == T_PTR) {
	    CvtAddrToPtr(host);
	} 
	result = GetHostInfoByName(servAddrPtr, queryClass, queryType, host, 
			&curHostInfo, 0);
    }

    switch (result) {
	case SUCCESS:
	    /*
	     *  If the query was for an address, then the &curHostInfo
	     *  variable can be used by Finger.
	     *  There's no need to print anything for other query types
	     *  because the info has already been printed.
	     */
	    if (queryType == T_A) {
		curHostValid = TRUE;
		PrintHostInfo(filePtr, "Name:", &curHostInfo);
	    }
	    break;

	/*
	 * No Authoritative answer was available but we got names
	 * of servers who know about the host.
	 */
	case NONAUTH:
	    PrintHostInfo(filePtr, "Name:", &curHostInfo);
	    break;

	case NO_INFO:
	    fprintf(stderr, "*** No %s (%s) records available for %s\n", 
			DecodeType(queryType), p_type(queryType), host);
	    break;

	case TIME_OUT:
	    fprintf(stderr, "*** Request to %s timed-out\n", serverName);
	    break;

	default:
	    fprintf(stderr, "*** %s can't find %s: %s\n", serverName, host,
		    DecodeError(result));
    }
    return result;
}

/*
 ******************************************************************************
 *
 *  LookupHost --
 *
 *	Asks the default name server for information about the
 *	specified host or domain. The information is printed
 *	if the lookup was successful.
 *
 *  Results:
 *	ERROR		- the output file could not be opened.
 *	+ results of DoLookup
 *
 ******************************************************************************
 */

int
LookupHost(string, putToFile)
    char	*string;
    Boolean	putToFile;
{
    char	host[NAME_LEN];
    char	file[PATH_MAX];
    int		result;

    /*
     *  Invalidate the current host information to prevent Finger 
     *  from using bogus info.
     */

    curHostValid = FALSE;

    /*
     *	 Parse the command string into the host and
     *	 optional output file name.
     *
     */
    sscanf(string, " " NAME_LEN_STR, host);	/* removes white space */

    if (!putToFile) {
	filePtr = stdout;
    } else {
	filePtr = OpenFile(string, file);
	if (filePtr == NULL) {
	    fprintf(stderr, "*** Can't open %s for writing\n", file);
	    return(ERROR);
	}
	fprintf(filePtr,"> %s\n", string);
    }

    PrintHostInfo(filePtr, "Server:", defaultPtr);

    result = DoLookup(host, defaultPtr, defaultServer);

    if (putToFile) {
	fclose(filePtr);
	filePtr = NULL;
    }
    return(result);
}

/*
 ******************************************************************************
 *
 *  LookupHostWithServer --
 *
 *	Asks the name server specified in the second argument for 
 *	information about the host or domain specified in the first
 *	argument. The information is printed if the lookup was successful.
 *
 *	Address info about the requested name server is obtained
 *	from the default name server. This routine will return an
 *	error if the default server doesn't have info about the 
 *	requested server. Thus an error return status might not
 *	mean the requested name server doesn't have info about the
 *	requested host.
 *
 *	Comments from LookupHost apply here, too.
 *
 *  Results:
 *	ERROR		- the output file could not be opened.
 *	+ results of DoLookup
 *
 ******************************************************************************
 */

int
LookupHostWithServer(string, putToFile)
    char	*string;
    Boolean	putToFile;
{
    char	file[PATH_MAX];
    char	host[NAME_LEN];
    char	server[NAME_LEN];
    int		result;
    static HostInfo serverInfo;

    curHostValid = FALSE;

    sscanf(string, " " NAME_LEN_STR " " NAME_LEN_STR, host, server);
    if (!putToFile) {
	filePtr = stdout;
    } else {
	filePtr = OpenFile(string, file);
	if (filePtr == NULL) {
	    fprintf(stderr, "*** Can't open %s for writing\n", file);
	    return(ERROR);
	}
	fprintf(filePtr,"> %s\n", string);
    }
    
    result = GetHostInfoByName(
		defaultPtr->addrList ?
		    (struct in_addr *) defaultPtr->addrList[0] :
		    (struct in_addr *) defaultPtr->servers[0]->addrList[0], 
		C_IN, T_A, server, &serverInfo, 1);

    if (result != SUCCESS) {
	fprintf(stderr,"*** Can't find address for server %s: %s\n", server,
		 DecodeError(result));
    } else {
	PrintHostInfo(filePtr, "Server:", &serverInfo);

	result = DoLookup(host, &serverInfo, server);
    }
    if (putToFile) {
	fclose(filePtr);
	filePtr = NULL;
    }
    return(result);
}

/*
 ******************************************************************************
 *
 *  SetOption -- 
 *
 *	This routine is used to change the state information
 *	that affect the lookups. The command format is
 *	   set keyword[=value]
 *	Most keywords can be abbreviated. Parsing is very simplistic--
 *	A value must not be separated from its keyword by white space.
 *
 *	Valid keywords:		Meaning:
 *	all			lists current values of options.
 *	ALL			lists current values of options, including
 *				  hidden options.
 *	[no]d2			turn on/off extra debugging mode.
 *	[no]debug		turn on/off debugging mode.
 *	[no]defname		use/don't use default domain name.
 *	[no]search		use/don't use domain search list.
 *	domain=NAME		set default domain name to NAME.
 *	[no]ignore		ignore/don't ignore trunc. errors.
 *	query=value		set default query type to value,
 *				value is one of the query types in RFC883
 *				without the leading T_.	(e.g., A, HINFO)
 *	[no]recurse		use/don't use recursive lookup.
 *	retry=#			set number of retries to #.
 *	root=NAME		change root server to NAME.
 *	time=#			set timeout length to #.
 *	[no]vc			use/don't use virtual circuit.
 *	port			TCP/UDP port to server.
 *
 * 	Deprecated:
 *	[no]primary		use/don't use primary server.
 *
 *  Results:
 *	SUCCESS		the command was parsed correctly.
 *	ERROR		the command was not parsed correctly.
 *
 ******************************************************************************
 */

int
SetOption(option)
    register char *option;
{
    char	type[NAME_LEN];
    char	*ptr;
    int		tmp;

    while (isspace(*option))
	++option;
    if (strncmp (option, "set ", 4) == 0)
	option += 4;
    while (isspace(*option))
	++option;

    if (*option == 0) {
	fprintf(stderr, "*** Invalid set command\n");
	return(ERROR);
    } else {
	if (strncmp(option, "all", 3) == 0) {
	    ShowOptions();
	} else if (strncmp(option, "ALL", 3) == 0) {
	    ShowOptions();
	} else if (strncmp(option, "d2", 2) == 0) {	/* d2 (more debug) */
	    _res.options |= (RES_DEBUG | RES_DEBUG2);
	} else if (strncmp(option, "nod2", 4) == 0) {
	    _res.options &= ~RES_DEBUG2;
	    printf("d2 mode disabled; still in debug mode\n");
	} else if (strncmp(option, "def", 3) == 0) {	/* defname */
	    _res.options |= RES_DEFNAMES;
	} else if (strncmp(option, "nodef", 5) == 0) {
	    _res.options &= ~RES_DEFNAMES;
	} else if (strncmp(option, "do", 2) == 0) {	/* domain */
	    ptr = strchr(option, '=');
	    if (ptr != NULL) {
		sscanf(++ptr, "%s", _res.defdname);
		res_re_init();
	    }
	} else if (strncmp(option, "deb", 1) == 0) {	/* debug */
	    _res.options |= RES_DEBUG;
	} else if (strncmp(option, "nodeb", 5) == 0) {
	    _res.options &= ~(RES_DEBUG | RES_DEBUG2);
	} else if (strncmp(option, "ig", 2) == 0) {	/* ignore */
	    _res.options |= RES_IGNTC;
	} else if (strncmp(option, "noig", 4) == 0) {
	    _res.options &= ~RES_IGNTC;
	} else if (strncmp(option, "po", 2) == 0) {	/* port */
	    ptr = strchr(option, '=');
	    if (ptr != NULL) {
		sscanf(++ptr, "%hu", &nsport);
	    }
#ifdef deprecated
	} else if (strncmp(option, "pri", 3) == 0) {	/* primary */
	    _res.options |= RES_PRIMARY;
	} else if (strncmp(option, "nopri", 5) == 0) {
	    _res.options &= ~RES_PRIMARY;
#endif
	} else if (strncmp(option, "q", 1) == 0 ||	/* querytype */
	  strncmp(option, "ty", 2) == 0) {		/* type */
	    ptr = strchr(option, '=');
	    if (ptr != NULL) {
		sscanf(++ptr, "%s", type);
		queryType = StringToType(type, queryType, stderr);
	    }
	} else if (strncmp(option, "cl", 2) == 0) {	/* query class */
	    ptr = strchr(option, '=');
	    if (ptr != NULL) {
		sscanf(++ptr, "%s", type);
		queryClass = StringToClass(type, queryClass, stderr);
	    }
	} else if (strncmp(option, "rec", 3) == 0) {	/* recurse */
	    _res.options |= RES_RECURSE;
	} else if (strncmp(option, "norec", 5) == 0) {
	    _res.options &= ~RES_RECURSE;
	} else if (strncmp(option, "ret", 3) == 0) {	/* retry */
	    ptr = strchr(option, '=');
	    if (ptr != NULL) {
		sscanf(++ptr, "%d", &tmp);
		if (tmp >= 0) {
		    _res.retry = tmp;
		}
	    }
	} else if (strncmp(option, "ro", 2) == 0) {	/* root */
	    ptr = strchr(option, '=');
	    if (ptr != NULL) {
		sscanf(++ptr, "%s", rootServerName);
	    }
	} else if (strncmp(option, "sea", 3) == 0) {	/* search list */
	    _res.options |= RES_DNSRCH;
	} else if (strncmp(option, "nosea", 5) == 0) {
	    _res.options &= ~RES_DNSRCH;
	} else if (strncmp(option, "srchl", 5) == 0) {	/* domain search list */
	    ptr = strchr(option, '=');
	    if (ptr != NULL) {
		res_dnsrch(++ptr);
	    }
	} else if (strncmp(option, "ti", 2) == 0) {	/* timeout */
	    ptr = strchr(option, '=');
	    if (ptr != NULL) {
		sscanf(++ptr, "%d", &tmp);
		if (tmp >= 0) {
		    _res.retrans = tmp;
		}
	    }
	} else if (strncmp(option, "v", 1) == 0) {	/* vc */
	    _res.options |= RES_USEVC;
	} else if (strncmp(option, "nov", 3) == 0) {
	    _res.options &= ~RES_USEVC;
	} else {
	    fprintf(stderr, "*** Invalid option: %s\n",  option);
	    return(ERROR);
	}
    }
    return(SUCCESS);
}

/*
 * Fake a reinitialization when the domain is changed.
 */
res_re_init()
{
    register char *cp, **pp;
    int n;

    /* find components of local domain that might be searched */
    pp = _res.dnsrch;
    *pp++ = _res.defdname;
    for (cp = _res.defdname, n = 0; *cp; cp++)
	if (*cp == '.')
	    n++;
    cp = _res.defdname;
    for (; n >= LOCALDOMAINPARTS && pp < _res.dnsrch + MAXDFLSRCH; n--) {
	cp = strchr(cp, '.');
	*pp++ = ++cp;
    }
    *pp = 0;
    _res.options |= RES_INIT;
}

#define SRCHLIST_SEP '/'

res_dnsrch(cp)
    register char *cp;
{
    register char **pp;
    int n;

    (void)strncpy(_res.defdname, cp, sizeof(_res.defdname) - 1);
    if ((cp = strchr(_res.defdname, '\n')) != NULL)
	    *cp = '\0';
    /*
     * Set search list to be blank-separated strings
     * on rest of line.
     */
    cp = _res.defdname;
    pp = _res.dnsrch;
    *pp++ = cp;
    for (n = 0; *cp && pp < _res.dnsrch + MAXDNSRCH; cp++) {
	    if (*cp == SRCHLIST_SEP) {
		    *cp = '\0';
		    n = 1;
	    } else if (n) {
		    *pp++ = cp;
		    n = 0;
	    }
    }
    if ((cp = strchr(pp[-1], SRCHLIST_SEP)) != NULL) {
	*cp = '\0';
    }
    *pp = NULL;
}


/*
 ******************************************************************************
 *
 *  ShowOptions --
 *
 *	Prints out the state information used by the resolver
 *	library and other options set by the user.
 *
 ******************************************************************************
 */

void
ShowOptions()
{
    register char **cp;

    PrintHostInfo(stdout, "Default Server:", defaultPtr);
    if (curHostValid) {
	PrintHostInfo(stdout, "Host:", &curHostInfo);
    }

    printf("Set options:\n");
    printf("  %sdebug  \t", (_res.options & RES_DEBUG) ? "" : "no");
    printf("  %sdefname\t", (_res.options & RES_DEFNAMES) ? "" : "no");
    printf("  %ssearch\t", (_res.options & RES_DNSRCH) ? "" : "no");
    printf("  %srecurse\n", (_res.options & RES_RECURSE) ? "" : "no");

    printf("  %sd2\t\t", (_res.options & RES_DEBUG2) ? "" : "no");
    printf("  %svc\t\t", (_res.options & RES_USEVC) ? "" : "no");
    printf("  %signoretc\t", (_res.options & RES_IGNTC) ? "" : "no");
    printf("  port=%u\n", nsport);

    printf("  querytype=%s\t", p_type(queryType));
    printf("  class=%s\t", p_class(queryClass));
    printf("  timeout=%d\t", _res.retrans);
    printf("  retry=%d\n", _res.retry);
    printf("  root=%s\n", rootServerName);
    printf("  domain=%s\n", _res.defdname);
    
    if (cp = _res.dnsrch) {
	printf("  srchlist=%s", *cp);
	for (cp++; *cp; cp++) {
	    printf("%c%s", SRCHLIST_SEP, *cp);
	}
	putchar('\n');
    }
    putchar('\n');
}
#undef SRCHLIST_SEP

/*
 ******************************************************************************
 *
 *  PrintHelp --
 *
 *	Displays the help file.
 *
 ******************************************************************************
 */

void
PrintHelp()
{
	char cmd[PATH_MAX];

	sprintf(cmd, "%s %s", pager, _PATH_HELPFILE);
	system(cmd);
}

/*
 ******************************************************************************
 *
 * CvtAddrToPtr --
 *
 *	Convert a dotted-decimal Internet address into the standard
 *	PTR format (reversed address with .in-arpa. suffix).
 *
 *	Assumes the argument buffer is large enougth to hold the result.
 *
 ******************************************************************************
 */

static void
CvtAddrToPtr(name)
    char *name;
{
    char *p;
    int ip[4];
    struct in_addr addr;

    if (IsAddr(name, &addr)) {
	p = inet_ntoa(addr);
	if (sscanf(p, "%d.%d.%d.%d", &ip[0], &ip[1], &ip[2], &ip[3]) == 4) {
	    sprintf(name, "%d.%d.%d.%d.in-addr.arpa.", 
		ip[3], ip[2], ip[1], ip[0]);
	}
    }
}

/*
 ******************************************************************************
 *
 * ReadRC --
 *
 *	Use the contents of ~/.nslookuprc as options.
 *
 ******************************************************************************
 */

static void
ReadRC()
{
    register FILE *fp;
    register char *cp;
    char buf[PATH_MAX];

    if ((cp = getenv("HOME")) != NULL &&
	(strlen(cp) + strlen(_PATH_NSLOOKUPRC)) < sizeof(buf)) {

	(void) strcpy(buf, cp);
	(void) strcat(buf, _PATH_NSLOOKUPRC);

	if ((fp = fopen(buf, "r")) != NULL) {
	    while (fgets(buf, sizeof(buf), fp) != NULL) {
		if ((cp = strchr(buf, '\n')) != NULL) {
		    *cp = '\0';
		}
		(void) SetOption(buf);
	    }
	    (void) fclose(fp);
	}
    }
}