char nbuf[MAXDNAME];
char nbuf[MAXDNAME*2+1];
const char *hostalias __P((const char *));int h_errno;/* * Formulate a normal query, send, and await answer. * Returned answer is placed in supplied buffer "answer". * Perform preliminary check of answer, returning success only * if no error is indicated and the answer count is nonzero. * Return the size of the response on success, -1 on error. * Error number is left in h_errno. * * Caller must parse answer and determine whether it answers the question. */intres_query(name, class, type, answer, anslen)	const char *name;	/* domain name */	int class, type;	/* class and type of query */	u_char *answer;		/* buffer to put answer */	int anslen;		/* size of answer buffer */{	u_char buf[MAXPACKET];	register HEADER *hp = (HEADER *) answer;	int n;	hp->rcode = NOERROR;	/* default */	if ((_res.options & RES_INIT) == 0 && res_init() == -1) {		h_errno = NETDB_INTERNAL;		return (-1);	}#ifdef DEBUG	if (_res.options & RES_DEBUG)		printf(";; res_query(%s, %d, %d)\n", name, class, type);#endif	n = res_mkquery(QUERY, name, class, type, NULL, 0, NULL,			buf, sizeof(buf));	if (n <= 0) {#ifdef DEBUG		if (_res.options & RES_DEBUG)			printf(";; res_query: mkquery failed\n");#endif		h_errno = NO_RECOVERY;		return (n);	}	n = res_send(buf, n, answer, anslen);	if (n < 0) {#ifdef DEBUG		if (_res.options & RES_DEBUG)			printf(";; res_query: send error\n");#endif		h_errno = TRY_AGAIN;		return (n);	}	if (hp->rcode != NOERROR || ntohs(hp->ancount) == 0) {#ifdef DEBUG		if (_res.options & RES_DEBUG)			printf(";; rcode = %d, ancount=%d\n", hp->rcode,			    ntohs(hp->ancount));#endif		switch (hp->rcode) {		case NXDOMAIN:			h_errno = HOST_NOT_FOUND;			break;		case SERVFAIL:			h_errno = TRY_AGAIN;			break;		case NOERROR:			h_errno = NO_DATA;			break;		case FORMERR:		case NOTIMP:		case REFUSED:		default:			h_errno = NO_RECOVERY;			break;		}		return (-1);	}	return (n);}/* * Formulate a normal query, send, and retrieve answer in supplied buffer. * Return the size of the response on success, -1 on error. * If enabled, implement search rules until answer or unrecoverable failure * is detected.  Error code, if any, is left in h_errno. */intres_search(name, class, type, answer, anslen)	const char *name;	/* domain name */	int class, type;	/* class and type of query */	u_char *answer;		/* buffer to put answer */	int anslen;		/* size of answer */{	register const char *cp, * const *domain;	HEADER *hp = (HEADER *) answer;	u_int dots;	int trailing_dot, ret, saved_herrno;	int got_nodata = 0, got_servfail = 0, tried_as_is = 0;	if ((_res.options & RES_INIT) == 0 && res_init() == -1) {		h_errno = NETDB_INTERNAL;		return (-1);	}	errno = 0;	h_errno = HOST_NOT_FOUND;	/* default, if we never query */	dots = 0;	for (cp = name; *cp; cp++)		dots += (*cp == '.');	trailing_dot = 0;	if (cp > name && *--cp == '.')		trailing_dot++;	/*	 * if there aren't any dots, it could be a user-level alias	 */	if (!dots && (cp = __hostalias(name)) != NULL)		return (res_query(cp, class, type, answer, anslen));	/*	 * If there are dots in the name already, let's just give it a try	 * 'as is'.  The threshold can be set with the "ndots" option.	 */	saved_herrno = -1;	if (dots >= _res.ndots) {		ret = res_querydomain(name, NULL, class, type, answer, anslen);		if (ret > 0)			return (ret);		saved_herrno = h_errno;		tried_as_is++;	}	/*	 * We do at least one level of search if	 *	- there is no dot and RES_DEFNAME is set, or	 *	- there is at least one dot, there is no trailing dot,	 *	  and RES_DNSRCH is set.	 */	if ((!dots && (_res.options & RES_DEFNAMES)) ||	    (dots && !trailing_dot && (_res.options & RES_DNSRCH))) {		int done = 0;		for (domain = (const char * const *)_res.dnsrch;		     *domain && !done;		     domain++) {			ret = res_querydomain(name, *domain, class, type,					      answer, anslen);			if (ret > 0)				return (ret);			/*			 * If no server present, give up.			 * If name isn't found in this domain,			 * keep trying higher domains in the search list			 * (if that's enabled).			 * On a NO_DATA error, keep trying, otherwise			 * a wildcard entry of another type could keep us			 * from finding this entry higher in the domain.			 * If we get some other error (negative answer or			 * server failure), then stop searching up,			 * but try the input name below in case it's			 * fully-qualified.			 */			if (errno == ECONNREFUSED) {				h_errno = TRY_AGAIN;				return (-1);			}			switch (h_errno) {			case NO_DATA:				got_nodata++;				/* FALLTHROUGH */			case HOST_NOT_FOUND:				/* keep trying */				break;			case TRY_AGAIN:				if (hp->rcode == SERVFAIL) {					/* try next search element, if any */					got_servfail++;					break;				}				/* FALLTHROUGH */			default:				/* anything else implies that we're done */				done++;			}			/* if we got here for some reason other than DNSRCH,			 * we only wanted one iteration of the loop, so stop.			 */			if (!(_res.options & RES_DNSRCH))				done++;		}	}	/* if we have not already tried the name "as is", do that now.	 * note that we do this regardless of how many dots were in the	 * name or whether it ends with a dot.	 */	if (!tried_as_is) {		ret = res_querydomain(name, NULL, class, type, answer, anslen);		if (ret > 0)			return (ret);	}	/* if we got here, we didn't satisfy the search.	 * if we did an initial full query, return that query's h_errno	 * (note that we wouldn't be here if that query had succeeded).	 * else if we ever got a nodata, send that back as the reason.	 * else send back meaningless h_errno, that being the one from	 * the last DNSRCH we did.	 */	if (saved_herrno != -1)		h_errno = saved_herrno;	else if (got_nodata)		h_errno = NO_DATA;	else if (got_servfail)		h_errno = TRY_AGAIN;	return (-1);}/* * Perform a call on res_query on the concatenation of name and domain, * removing a trailing dot from name if domain is NULL. */intres_querydomain(name, domain, class, type, answer, anslen)	const char *name, *domain;	int class, type;	/* class and type of query */	u_char *answer;		/* buffer to put answer */	int anslen;		/* size of answer */{	char nbuf[MAXDNAME];	const char *longname = nbuf;	int n;	if ((_res.options & RES_INIT) == 0 && res_init() == -1) {		h_errno = NETDB_INTERNAL;		return (-1);	}#ifdef DEBUG	if (_res.options & RES_DEBUG)		printf(";; res_querydomain(%s, %s, %d, %d)\n",		       name, domain?domain:"<Nil>", class, type);#endif	if (domain == NULL) {		/*		 * Check for trailing '.';		 * copy without '.' if present.		 */		n = strlen(name) - 1;		if (n != (0 - 1) && name[n] == '.' && n < sizeof(nbuf) - 1) {			bcopy(name, nbuf, n);			nbuf[n] = '\0';		} else			longname = name;	} else		sprintf(nbuf, "%.*s.%.*s", MAXDNAME, name, MAXDNAME, domain);	return (res_query(longname, class, type, answer, anslen));}const char *hostalias(name)	register const char *name;{	register char *cp1, *cp2;	FILE *fp;	char *file;	char buf[BUFSIZ];	static char abuf[MAXDNAME];	size_t len;	if (_res.options & RES_NOALIASES)		return (NULL);	file = getenv("HOSTALIASES");	if (issetugid() != 0 || file == NULL || (fp = fopen(file, "r")) == NULL)		return (NULL);	setbuf(fp, NULL);	while ((cp1 = fgetln(fp, &len)) != NULL) {		if (cp1[len-1] == '\n')			len--;		if (len >= sizeof(buf) || len == 0)			continue;		(void)memcpy(buf, cp1, len);		buf[len] = '\0';				for (cp1 = buf; *cp1 && !isspace(*cp1); ++cp1)			;		if (!*cp1)			break;		*cp1 = '\0';		if (!strcasecmp(buf, name)) {			while (isspace(*++cp1))				;			if (!*cp1)				break;			for (cp2 = cp1 + 1; *cp2 && !isspace(*cp2); ++cp2)				;			strncpy(abuf, cp1, sizeof(abuf) - 1);			abuf[sizeof(abuf) - 1] = *cp2 = '\0';			fclose(fp);			return (abuf);		}	}	fclose(fp);	return (NULL);}