text: /*	$NetBSD: getaddrinfo.c,v 1.91.6.1 2009/01/26 00:27:34 snj Exp $	*/
  /*	$KAME: getaddrinfo.c,v 1.29 2000/08/31 17:26:57 itojun Exp $	*/
  
  /*
   * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
   * 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. Neither the name of the project 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 PROJECT 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 PROJECT 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.
   */
  
  /*
   * Issues to be discussed:
   * - Return values.  There are nonstandard return values defined and used
   *   in the source code.  This is because RFC2553 is silent about which error
   *   code must be returned for which situation.
   * - IPv4 classful (shortened) form.  RFC2553 is silent about it.  XNET 5.2
   *   says to use inet_aton() to convert IPv4 numeric to binary (alows
   *   classful form as a result).
   *   current code - disallow classful form for IPv4 (due to use of inet_pton).
   * - freeaddrinfo(NULL).  RFC2553 is silent about it.  XNET 5.2 says it is
   *   invalid.
   *   current code - SEGV on freeaddrinfo(NULL)
   * Note:
   * - The code filters out AFs that are not supported by the kernel,
   *   when globbing NULL hostname (to loopback, or wildcard).  Is it the right
   *   thing to do?  What is the relationship with post-RFC2553 AI_ADDRCONFIG
   *   in ai_flags?
   * - (post-2553) semantics of AI_ADDRCONFIG itself is too vague.
   *   (1) what should we do against numeric hostname (2) what should we do
   *   against NULL hostname (3) what is AI_ADDRCONFIG itself.  AF not ready?
   *   non-loopback address configured?  global address configured?
   */
  
  #include <sys/cdefs.h>
  #if defined(LIBC_SCCS) && !defined(lint)
  __RCSID("$NetBSD: getaddrinfo.c,v 1.91.6.1 2009/01/26 00:27:34 snj Exp $");
  #endif /* LIBC_SCCS and not lint */
  
  #define INET6   1
  
  #include "namespace.h"
  #include <sys/types.h>
  #include <sys/param.h>
  #include <sys/socket.h>
  #include <net/if.h>
  #include <netinet/in.h>
  #include <arpa/inet.h>
  #include <arpa/nameser.h>
  #include <assert.h>
  #include <ctype.h>
  #include <errno.h>
  #include <netdb.h>
  #include <resolv.h>
  #include <stddef.h>
  #include <stdio.h>
  #include <stdlib.h>
  #include <string.h>
  #include <unistd.h>
  
  #include <stdarg.h>
  #include <nsswitch.h>
  #include <resolv.h>
  
  //#ifdef YP
  //#include <rpc/rpc.h>
  //#include <rpcsvc/yp_prot.h>
  //#include <rpcsvc/ypclnt.h>
  //#endif
  
  #include <net/servent.h>
  
  #define endservent_r(svd)   endservent()
  #define res_nmkquery(state,op,dname,class,type,data,datalen,newrr_in,buf,buflen)  res_mkquery( op, dname, class, type, data, datalen, newrr_in, buf, buflen )
  #define res_nsend(state,buf,buflen,ans,anssiz)    res_send ( buf, buflen, ans, anssiz )
  
  /* Things involving an internal (static) resolver context. */
  __BEGIN_DECLS
  #define __res_get_state()   (( 0 != _res.nscount ) ? &_res : NULL )
  #define __res_put_state(state)
  #define __res_state()   _res
  __END_DECLS
  
  #ifdef __weak_alias
  __weak_alias(getaddrinfo,_getaddrinfo)
  __weak_alias(freeaddrinfo,_freeaddrinfo)
  __weak_alias(gai_strerror,_gai_strerror)
  #endif
  
  #define SUCCESS 0
  #define ANY 0
  #define YES 1
  #define NO  0
  
  static const char in_addrany[] = { 0, 0, 0, 0 };
  static const char in_loopback[] = { 127, 0, 0, 1 };
  #ifdef INET6
  static const char in6_addrany[] = {
  	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
  };
  static const char in6_loopback[] = {
  	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1
  };
  #endif
  
  static const struct afd {
  	int a_af;
  	int a_addrlen;
  	int a_socklen;
  	int a_off;
  	const char *a_addrany;
  	const char *a_loopback;	
  	int a_scoped;
  } afdl [] = {
  #ifdef INET6
  	{PF_INET6, sizeof(struct in6_addr),
  	 sizeof(struct sockaddr_in6),
  	 offsetof(struct sockaddr_in6, sin6_addr),
  	 in6_addrany, in6_loopback, 1},
  #endif
  	{PF_INET, sizeof(struct in_addr),
  	 sizeof(struct sockaddr_in),
  	 offsetof(struct sockaddr_in, sin_addr),
  	 in_addrany, in_loopback, 0},
  	{0, 0, 0, 0, NULL, NULL, 0},
  };
  
  struct explore {
  	int e_af;
  	int e_socktype;
  	int e_protocol;
  	const char *e_protostr;
  	int e_wild;
  #define WILD_AF(ex)		((ex)->e_wild & 0x01)
  #define WILD_SOCKTYPE(ex)	((ex)->e_wild & 0x02)
  #define WILD_PROTOCOL(ex)	((ex)->e_wild & 0x04)
  };
  
  static const struct explore explore[] = {
  #if 0
  	{ PF_LOCAL, 0, ANY, ANY, NULL, 0x01 },
  #endif
  #ifdef INET6
  	{ PF_INET6, SOCK_DGRAM, IPPROTO_UDP, "udp", 0x07 },
  	{ PF_INET6, SOCK_STREAM, IPPROTO_TCP, "tcp", 0x07 },
  	{ PF_INET6, SOCK_RAW, ANY, NULL, 0x05 },
  #endif
  	{ PF_INET, SOCK_DGRAM, IPPROTO_UDP, "udp", 0x07 },
  	{ PF_INET, SOCK_STREAM, IPPROTO_TCP, "tcp", 0x07 },
  	{ PF_INET, SOCK_RAW, ANY, NULL, 0x05 },
  	{ PF_UNSPEC, SOCK_DGRAM, IPPROTO_UDP, "udp", 0x07 },
  	{ PF_UNSPEC, SOCK_STREAM, IPPROTO_TCP, "tcp", 0x07 },
  	{ PF_UNSPEC, SOCK_RAW, ANY, NULL, 0x05 },
  	{ -1, 0, 0, NULL, 0 },
  };
  
  #ifdef INET6
  #define PTON_MAX	16
  #else
  #define PTON_MAX	4
  #endif
  
  static const ns_src default_dns_files[] = {
  	{ NSSRC_FILES, 	NS_SUCCESS },
  	{ NSSRC_DNS, 	NS_SUCCESS },
  	{ 0, 0 }
  };
  
  #define MAXPACKET	(64*1024)
  
  typedef union {
  	HEADER hdr;
  	u_char buf[MAXPACKET];
  } querybuf;
  
  struct res_target {
  	struct res_target *next;
  	const char *name;	/* domain name */
  	int qclass, qtype;	/* class and type of query */
  	u_char *answer;		/* buffer to put answer */
  	int anslen;		/* size of answer buffer */
  	int n;			/* result length */
  };
  
  static int str2number(const char *);
  static int explore_fqdn(const struct addrinfo *, const char *,
  	const char *, struct addrinfo **, struct servent_data *);
  static int explore_null(const struct addrinfo *,
  	const char *, struct addrinfo **, struct servent_data *);
  static int explore_numeric(const struct addrinfo *, const char *,
  	const char *, struct addrinfo **, const char *, struct servent_data *);
  static int explore_numeric_scope(const struct addrinfo *, const char *,
  	const char *, struct addrinfo **, struct servent_data *);
  static int get_canonname(const struct addrinfo *,
  	struct addrinfo *, const char *);
  static struct addrinfo *get_ai(const struct addrinfo *,
  	const struct afd *, const char *);
  static int get_portmatch(const struct addrinfo *, const char *,
      struct servent_data *);
  static int get_port(const struct addrinfo *, const char *, int,
      struct servent_data *);
  static const struct afd *find_afd(int);
  #ifdef INET6
  static int ip6_str2scopeid(char *, struct sockaddr_in6 *, u_int32_t *);
  #endif
  
  static struct addrinfo *getanswer(const querybuf *, int, const char *, int,
  	const struct addrinfo *);
  static void aisort(struct addrinfo *s, res_state res);
  static int _dns_getaddrinfo(void *, void *, va_list);
  static void _sethtent(FILE **);
  static void _endhtent(FILE **);
  static struct addrinfo *_gethtent(FILE **, const char *,
      const struct addrinfo *);
  static int _files_getaddrinfo(void *, void *, va_list);
  #ifdef YP
  static struct addrinfo *_yphostent(char *, const struct addrinfo *);
  static int _yp_getaddrinfo(void *, void *, va_list);
  #endif
  
  static int res_queryN(const char *, struct res_target *, res_state);
  static int res_searchN(const char *, struct res_target *, res_state);
  static int res_querydomainN(const char *, const char *,
  	struct res_target *, res_state);
  
  static const char * const ai_errlist[] = {
  	"Success",
  	"Address family for hostname not supported",	/* EAI_ADDRFAMILY */
  	"Temporary failure in name resolution",		/* EAI_AGAIN      */
  	"Invalid value for ai_flags",		       	/* EAI_BADFLAGS   */
  	"Non-recoverable failure in name resolution", 	/* EAI_FAIL       */
  	"ai_family not supported",			/* EAI_FAMILY     */
  	"Memory allocation failure", 			/* EAI_MEMORY     */
  	"No address associated with hostname", 		/* EAI_NODATA     */
  	"hostname nor servname provided, or not known",	/* EAI_NONAME     */
  	"servname not supported for ai_socktype",	/* EAI_SERVICE    */
  	"ai_socktype not supported", 			/* EAI_SOCKTYPE   */
  	"System error returned in errno", 		/* EAI_SYSTEM     */
  	"Invalid value for hints",			/* EAI_BADHINTS	  */
  	"Resolved protocol is unknown",			/* EAI_PROTOCOL   */
  	"Argument buffer overflow",			/* EAI_OVERFLOW   */
  	"Unknown error", 				/* EAI_MAX        */
  };
  
  /* XXX macros that make external reference is BAD. */
  
  #define GET_AI(ai, afd, addr) 					\
  do { 								\
  	/* external reference: pai, error, and label free */ 	\
  	(ai) = get_ai(pai, (afd), (addr)); 			\
  	if ((ai) == NULL) { 					\
  		error = EAI_MEMORY; 				\
  		goto free; 					\
  	} 							\
  } while (/*CONSTCOND*/0)
  
  #define GET_PORT(ai, serv, svd) 				\
  do { 								\
  	/* external reference: error and label free */ 		\
  	error = get_port((ai), (serv), 0, (svd)); 		\
  	if (error != 0) 					\
  		goto free; 					\
  } while (/*CONSTCOND*/0)
  
  #define GET_CANONNAME(ai, str) 					\
  do { 								\
  	/* external reference: pai, error and label free */ 	\
  	error = get_canonname(pai, (ai), (str)); 		\
  	if (error != 0) 					\
  		goto free; 					\
  } while (/*CONSTCOND*/0)
  
  #define ERR(err) 						\
  do { 								\
  	/* external reference: error, and label bad */ 		\
  	error = (err); 						\
  	goto bad; 						\
  	/*NOTREACHED*/ 						\
  } while (/*CONSTCOND*/0)
  
  #define MATCH_FAMILY(x, y, w) 						\
  	((x) == (y) || (/*CONSTCOND*/(w) && ((x) == PF_UNSPEC || 	\
  	    (y) == PF_UNSPEC)))	
  #define MATCH(x, y, w) 							\
  	((x) == (y) || (/*CONSTCOND*/(w) && ((x) == ANY || (y) == ANY)))
  
  int nsdispatch(void *result, const ns_dtab dist_tab[], const char* database,
                 const char *method, const ns_src defaults[], ...)
  {
    return NS_NOTFOUND;
  }
  
  const char *
  gai_strerror(int ecode)
  {
  	if (ecode < 0 || ecode > EAI_MAX)
  		ecode = EAI_MAX;
  	return ai_errlist[ecode];
  }
  
  void
  freeaddrinfo(struct addrinfo *ai)
  {
  	struct addrinfo *next;
  
  	_DIAGASSERT(ai != NULL);
  
  	do {
  		next = ai->ai_next;
  		if (ai->ai_canonname)
  			free(ai->ai_canonname);
  		/* no need to free(ai->ai_addr) */
  		free(ai);
  		ai = next;
  	} while (ai);
  }
  
  static int
  str2number(const char *p)
  {
  	char *ep;
  	unsigned long v;
  
  	_DIAGASSERT(p != NULL);
  
  	if (*p == '\0')
  		return -1;
  	ep = NULL;
  	errno = 0;
  	v = strtoul(p, &ep, 10);
  	if (errno == 0 && ep && *ep == '\0' && v <= UINT_MAX)
  		return v;
  	else
  		return -1;
  }
  
  int
  getaddrinfo(const char *hostname, const char *servname,
      const struct addrinfo *hints, struct addrinfo **res)
  {
  	struct addrinfo sentinel;
  	struct addrinfo *cur;
  	int error = 0;
  	struct addrinfo ai;
  	struct addrinfo ai0;
  	struct addrinfo *pai;
  	const struct explore *ex;
  	struct servent_data svd;
  
  	/* hostname is allowed to be NULL */
  	/* servname is allowed to be NULL */
  	/* hints is allowed to be NULL */
  	_DIAGASSERT(res != NULL);
  
  	(void)memset(&svd, 0, sizeof(svd));
  	memset(&sentinel, 0, sizeof(sentinel));
  	cur = &sentinel;
  	memset(&ai, 0, sizeof(ai));
  	pai = &ai;
  	pai->ai_flags = 0;
  	pai->ai_family = PF_UNSPEC;
  	pai->ai_socktype = ANY;
  	pai->ai_protocol = ANY;
  	pai->ai_addrlen = 0;
  	pai->ai_canonname = NULL;
  	pai->ai_addr = NULL;
  	pai->ai_next = NULL;
  	
  	if (hostname == NULL && servname == NULL)
  		return EAI_NONAME;
  	if (hints) {
  		/* error check for hints */
  		if (hints->ai_addrlen || hints->ai_canonname ||
  		    hints->ai_addr || hints->ai_next)
  			ERR(EAI_BADHINTS); /* xxx */
  		if (hints->ai_flags & ~AI_MASK)
  			ERR(EAI_BADFLAGS);
  		switch (hints->ai_family) {
  		case PF_UNSPEC:
  		case PF_INET:
  #ifdef INET6
  		case PF_INET6:
  #endif
  			break;
  		default:
  			ERR(EAI_FAMILY);
  		}
  		memcpy(pai, hints, sizeof(*pai));
  
  		/*
  		 * if both socktype/protocol are specified, check if they
  		 * are meaningful combination.
  		 */
  		if (pai->ai_socktype != ANY && pai->ai_protocol != ANY) {
  			for (ex = explore; ex->e_af >= 0; ex++) {
  				if (pai->ai_family != ex->e_af)
  					continue;
  				if (ex->e_socktype == ANY)
  					continue;
  				if (ex->e_protocol == ANY)
  					continue;
  				if (pai->ai_socktype == ex->e_socktype
  				 && pai->ai_protocol != ex->e_protocol) {
  					ERR(EAI_BADHINTS);
  				}
  			}
  		}
  	}
  
  	/*
  	 * check for special cases.  (1) numeric servname is disallowed if
  	 * socktype/protocol are left unspecified. (2) servname is disallowed
  	 * for raw and other inet{,6} sockets.
  	 */
  	if (MATCH_FAMILY(pai->ai_family, PF_INET, 1)
  #ifdef PF_INET6
  	 || MATCH_FAMILY(pai->ai_family, PF_INET6, 1)
  #endif
  	    ) {
  		ai0 = *pai;	/* backup *pai */
  
  		if (pai->ai_family == PF_UNSPEC) {
  #ifdef PF_INET6
  			pai->ai_family = PF_INET6;
  #else
  			pai->ai_family = PF_INET;
  #endif
  		}
  		error = get_portmatch(pai, servname, &svd);
  		if (error)
  			ERR(error);
  
  		*pai = ai0;
  	}
  
  	ai0 = *pai;
  
  	/* NULL hostname, or numeric hostname */
  	for (ex = explore; ex->e_af >= 0; ex++) {
  		*pai = ai0;
  
  		/* PF_UNSPEC entries are prepared for DNS queries only */
  		if (ex->e_af == PF_UNSPEC)
  			continue;
  
  		if (!MATCH_FAMILY(pai->ai_family, ex->e_af, WILD_AF(ex)))
  			continue;
  		if (!MATCH(pai->ai_socktype, ex->e_socktype, WILD_SOCKTYPE(ex)))
  			continue;
  		if (!MATCH(pai->ai_protocol, ex->e_protocol, WILD_PROTOCOL(ex)))
  			continue;
  
  		if (pai->ai_family == PF_UNSPEC)
  			pai->ai_family = ex->e_af;
  		if (pai->ai_socktype == ANY && ex->e_socktype != ANY)
  			pai->ai_socktype = ex->e_socktype;
  		if (pai->ai_protocol == ANY && ex->e_protocol != ANY)
  			pai->ai_protocol = ex->e_protocol;
  
  		if (hostname == NULL)
  			error = explore_null(pai, servname, &cur->ai_next,
  			    &svd);
  		else
  			error = explore_numeric_scope(pai, hostname, servname,
  			    &cur->ai_next, &svd);
  
  		if (error)
  			goto free;
  
  		while (cur->ai_next)
  			cur = cur->ai_next;
  	}
  
  	/*
  	 * XXX
  	 * If numeric representation of AF1 can be interpreted as FQDN
  	 * representation of AF2, we need to think again about the code below.
  	 */
  	if (sentinel.ai_next)
  		goto good;
  
  	if (hostname == NULL)
  		ERR(EAI_NODATA);
  	if (pai->ai_flags & AI_NUMERICHOST)
  		ERR(EAI_NONAME);
  
  	/*
  	 * hostname as alphabetical name.
  	 * we would like to prefer AF_INET6 than AF_INET, so we'll make a
  	 * outer loop by AFs.
  	 */
  	for (ex = explore; ex->e_af >= 0; ex++) {
  		*pai = ai0;
  
  		/* require exact match for family field */
  		if (pai->ai_family != ex->e_af)
  			continue;
  
  		if (!MATCH(pai->ai_socktype, ex->e_socktype,
  				WILD_SOCKTYPE(ex))) {
  			continue;
  		}
  		if (!MATCH(pai->ai_protocol, ex->e_protocol,
  				WILD_PROTOCOL(ex))) {
  			continue;
  		}
  
  		if (pai->ai_socktype == ANY && ex->e_socktype != ANY)
  			pai->ai_socktype = ex->e_socktype;
  		if (pai->ai_protocol == ANY && ex->e_protocol != ANY)
  			pai->ai_protocol = ex->e_protocol;
  
  		error = explore_fqdn(pai, hostname, servname, &cur->ai_next,
  		    &svd);
  
  		while (cur && cur->ai_next)
  			cur = cur->ai_next;
  	}
  
  	/* XXX */
  	if (sentinel.ai_next)
  		error = 0;
  
  	if (error)
  		goto free;
  
  	if (sentinel.ai_next) {
   good:
  		endservent_r(&svd);
  		*res = sentinel.ai_next;
  		return SUCCESS;
  	} else
  		error = EAI_FAIL;
   free:
   bad:
  	endservent_r(&svd);
  	if (sentinel.ai_next)
  		freeaddrinfo(sentinel.ai_next);
  	*res = NULL;
  	return error;
  }
  
  static const ns_dtab dtab[] = {
    NS_FILES_CB(((nss_method)_files_getaddrinfo), NULL)
    { NSSRC_DNS, ((nss_method)_dns_getaddrinfo), NULL },  /* force -DHESIOD */
    NS_NIS_CB(_yp_getaddrinfo, NULL)
    NS_NULL_CB
  };
  
  /*
   * FQDN hostname, DNS lookup
   */
  static int
  explore_fqdn(const struct addrinfo *pai, const char *hostname,
      const char *servname, struct addrinfo **res, struct servent_data *svd)
  {
  	struct addrinfo *result;
  	struct addrinfo *cur;
  	int error = 0;
  
  	_DIAGASSERT(pai != NULL);
  	/* hostname may be NULL */
  	/* servname may be NULL */
  	_DIAGASSERT(res != NULL);
  
  	result = NULL;
  
  	/*
  	 * if the servname does not match socktype/protocol, ignore it.
  	 */
  	if (get_portmatch(pai, servname, svd) != 0)
  		return 0;
  
  	switch (nsdispatch(&result, dtab, NSDB_HOSTS, "getaddrinfo",
  			default_dns_files, hostname, pai)) {
  	case NS_TRYAGAIN:
  		error = EAI_AGAIN;
  		goto free;
  	case NS_UNAVAIL:
  		error = EAI_FAIL;
  		goto free;
  	case NS_NOTFOUND:
  		error = EAI_NODATA;
  		goto free;
  	case NS_SUCCESS:
  		error = 0;
  		for (cur = result; cur; cur = cur->ai_next) {
  			GET_PORT(cur, servname, svd);
  			/* canonname should be filled already */
  		}
  		break;
  	}
  
  	*res = result;
  
  	return 0;
  
  free:
  	if (result)
  		freeaddrinfo(result);
  	return error;
  }
  
  /*
   * hostname == NULL.
   * passive socket -> anyaddr (0.0.0.0 or ::)
   * non-passive socket -> localhost (127.0.0.1 or ::1)
   */
  static int
  explore_null(const struct addrinfo *pai, const char *servname,
      struct addrinfo **res, struct servent_data *svd)
  {
  	int s;
  	const struct afd *afd;
  	struct addrinfo *cur;
  	struct addrinfo sentinel;
  	int error;
  
  	_DIAGASSERT(pai != NULL);
  	/* servname may be NULL */
  	_DIAGASSERT(res != NULL);
  
  	*res = NULL;
  	sentinel.ai_next = NULL;
  	cur = &sentinel;
  
  	/*
  	 * filter out AFs that are not supported by the kernel
  	 * XXX errno?
  	 */
  	s = socket(pai->ai_family, SOCK_DGRAM, 0);
  	if (s < 0) {
  		if (errno != EMFILE)
  			return 0;
  	} else
  		close(s);
  
  	/*
  	 * if the servname does not match socktype/protocol, ignore it.
  	 */
  	if (get_portmatch(pai, servname, svd) != 0)
  		return 0;
  
  	afd = find_afd(pai->ai_family);
  	if (afd == NULL)
  		return 0;
  
  	if (pai->ai_flags & AI_PASSIVE) {
  		GET_AI(cur->ai_next, afd, afd->a_addrany);
  		/* xxx meaningless?
  		 * GET_CANONNAME(cur->ai_next, "anyaddr");
  		 */
  		GET_PORT(cur->ai_next, servname, svd);
  	} else {
  		GET_AI(cur->ai_next, afd, afd->a_loopback);
  		/* xxx meaningless?
  		 * GET_CANONNAME(cur->ai_next, "localhost");
  		 */
  		GET_PORT(cur->ai_next, servname, svd);
  	}
  	cur = cur->ai_next;
  
  	*res = sentinel.ai_next;
  	return 0;
  
  free:
  	if (sentinel.ai_next)
  		freeaddrinfo(sentinel.ai_next);
  	return error;
  }
  
  /*
   * numeric hostname
   */
  static int
  explore_numeric(const struct addrinfo *pai, const char *hostname,
      const char *servname, struct addrinfo **res, const char *canonname,
      struct servent_data *svd)
  {
  	const struct afd *afd;
  	struct addrinfo *cur;
  	struct addrinfo sentinel;
  	int error;
  	char pton[PTON_MAX];
  
  	_DIAGASSERT(pai != NULL);
  	/* hostname may be NULL */
  	/* servname may be NULL */
  	_DIAGASSERT(res != NULL);
  
  	*res = NULL;
  	sentinel.ai_next = NULL;
  	cur = &sentinel;
  
  	/*
  	 * if the servname does not match socktype/protocol, ignore it.
  	 */
  	if (get_portmatch(pai, servname, svd) != 0)
  		return 0;
  
  	afd = find_afd(pai->ai_family);
  	if (afd == NULL)
  		return 0;
  
  	switch (afd->a_af) {
  #if 0 /*X/Open spec*/
  	case AF_INET:
  		if (inet_aton(hostname, (struct in_addr *)pton) == 1) {
  			if (pai->ai_family == afd->a_af ||
  			    pai->ai_family == PF_UNSPEC /*?*/) {
  				GET_AI(cur->ai_next, afd, pton);
  				GET_PORT(cur->ai_next, servname, svd);
  				if ((pai->ai_flags & AI_CANONNAME)) {
  					/*
  					 * Set the numeric address itself as
  					 * the canonical name, based on a
  					 * clarification in rfc2553bis-03.
  					 */
  					GET_CANONNAME(cur->ai_next, canonname);
  				}
  				while (cur && cur->ai_next)
  					cur = cur->ai_next;
  			} else
  				ERR(EAI_FAMILY);	/*xxx*/
  		}
  		break;
  #endif
  	default:
  		if (inet_pton(afd->a_af, hostname, pton) == 1) {
  			if (pai->ai_family == afd->a_af ||
  			    pai->ai_family == PF_UNSPEC /*?*/) {
  				GET_AI(cur->ai_next, afd, pton);
  				GET_PORT(cur->ai_next, servname, svd);
  				if ((pai->ai_flags & AI_CANONNAME)) {
  					/*
  					 * Set the numeric address itself as
  					 * the canonical name, based on a
  					 * clarification in rfc2553bis-03.
  					 */
  					GET_CANONNAME(cur->ai_next, canonname);
  				}
  				while (cur->ai_next)
  					cur = cur->ai_next;
  			} else
  				ERR(EAI_FAMILY);	/*xxx*/
  		}
  		break;
  	}
  
  	*res = sentinel.ai_next;
  	return 0;
  
  free:
  bad:
  	if (sentinel.ai_next)
  		freeaddrinfo(sentinel.ai_next);
  	return error;
  }
  
  /*
   * numeric hostname with scope
   */
  static int
  explore_numeric_scope(const struct addrinfo *pai, const char *hostname,
      const char *servname, struct addrinfo **res, struct servent_data *svd)
  {
  #if !defined(SCOPE_DELIMITER) || !defined(INET6)
  	return explore_numeric(pai, hostname, servname, res, hostname, svd);
  #else
  	const struct afd *afd;
  	struct addrinfo *cur;
  	int error;
  	char *cp, *hostname2 = NULL, *scope, *addr;
  	struct sockaddr_in6 *sin6;
  
  	_DIAGASSERT(pai != NULL);
  	/* hostname may be NULL */
  	/* servname may be NULL */
  	_DIAGASSERT(res != NULL);
  
  	/*
  	 * if the servname does not match socktype/protocol, ignore it.
  	 */
  	if (get_portmatch(pai, servname, svd) != 0)
  		return 0;
  
  	afd = find_afd(pai->ai_family);
  	if (afd == NULL)
  		return 0;
  
  	if (!afd->a_scoped)
  		return explore_numeric(pai, hostname, servname, res, hostname,
  		    svd);
  
  	cp = strchr(hostname, SCOPE_DELIMITER);
  	if (cp == NULL)
  		return explore_numeric(pai, hostname, servname, res, hostname,
  		    svd);
  
  	/*
  	 * Handle special case of <scoped_address><delimiter><scope id>
  	 */
  	hostname2 = strdup(hostname);
  	if (hostname2 == NULL)
  		return EAI_MEMORY;
  	/* terminate at the delimiter */
  	hostname2[cp - hostname] = '\0';
  	addr = hostname2;
  	scope = cp + 1;
  
  	error = explore_numeric(pai, addr, servname, res, hostname, svd);
  	if (error == 0) {
  		u_int32_t scopeid;
  
  		for (cur = *res; cur; cur = cur->ai_next) {
  			if (cur->ai_family != AF_INET6)
  				continue;
  			sin6 = (struct sockaddr_in6 *)(void *)cur->ai_addr;
  			if (ip6_str2scopeid(scope, sin6, &scopeid) == -1) {
  				free(hostname2);
  				return(EAI_NODATA); /* XXX: is return OK? */
  			}
  			sin6->sin6_scope_id = scopeid;
  		}
  	}
  
  	free(hostname2);
  
  	return error;
  #endif
  }
  
  static int
  get_canonname(const struct addrinfo *pai, struct addrinfo *ai, const char *str)
  {
  
  	_DIAGASSERT(pai != NULL);
  	_DIAGASSERT(ai != NULL);
  	_DIAGASSERT(str != NULL);
  
  	if ((pai->ai_flags & AI_CANONNAME) != 0) {
  		ai->ai_canonname = strdup(str);
  		if (ai->ai_canonname == NULL)
  			return EAI_MEMORY;
  	}
  	return 0;
  }
  
  static struct addrinfo *
  get_ai(const struct addrinfo *pai, const struct afd *afd, const char *addr)
  {
  	char *p;
  	struct addrinfo *ai;
  
  	_DIAGASSERT(pai != NULL);
  	_DIAGASSERT(afd != NULL);
  	_DIAGASSERT(addr != NULL);
  
  	ai = (struct addrinfo *)malloc(sizeof(struct addrinfo)
  		+ (afd->a_socklen));
  	if (ai == NULL)
  		return NULL;
  
  	memcpy(ai, pai, sizeof(struct addrinfo));
  	ai->ai_addr = (struct sockaddr *)(void *)(ai + 1);
  	memset(ai->ai_addr, 0, (size_t)afd->a_socklen);
  	ai->ai_addr->sa_len = (uint8_t)afd->a_socklen;
  	ai->ai_addrlen = afd->a_socklen;
  	ai->ai_family = afd->a_af;
  	ai->ai_addr->sa_family = (sa_family_t)ai->ai_family;
  	p = (char *)(void *)(ai->ai_addr);
  	memcpy(p + afd->a_off, addr, (size_t)afd->a_addrlen);
  	return ai;
  }
  
  static int
  get_portmatch(const struct addrinfo *ai, const char *servname,
      struct servent_data *svd)
  {
  
  	_DIAGASSERT(ai != NULL);
  	/* servname may be NULL */
  
  	return get_port(ai, servname, 1, svd);
  }
  
  static int
  get_port(const struct addrinfo *ai, const char *servname, int matchonly,
      struct servent_data *svd)
  {
  	const char *proto;
  	struct servent *sp;
  	int port;
  	int allownumeric;
  
  	_DIAGASSERT(ai != NULL);
  	/* servname may be NULL */
  
  	if (servname == NULL)
  		return 0;
  	switch (ai->ai_family) {
  	case AF_INET:
  #ifdef AF_INET6
  	case AF_INET6:
  #endif
  		break;
  	default:
  		return 0;
  	}
  
  	switch (ai->ai_socktype) {
  	case SOCK_RAW:
  		return EAI_SERVICE;
  	case SOCK_DGRAM:
  	case SOCK_STREAM:
  		allownumeric = 1;
  		break;
  	case ANY:
  		/*
  		 * This was 0.  It is now 1 so that queries specifying
  		 * a NULL hint, or hint without socktype (but, hopefully,
  		 * with protocol) and numeric address actually work.
  		 */
  		allownumeric = 1;
  		break;
  	default:
  		return EAI_SOCKTYPE;
  	}
  
  	port = str2number(servname);
  	if (port >= 0) {
  		if (!allownumeric)
  			return EAI_SERVICE;
  		if (port < 0 || port > 65535)
  			return EAI_SERVICE;
  		port = htons(port);
  	} else {
  //		struct servent sv;
  		if (ai->ai_flags & AI_NUMERICSERV)
  			return EAI_NONAME;
  
  		switch (ai->ai_socktype) {
  		case SOCK_DGRAM:
  			proto = "udp";
  			break;
  		case SOCK_STREAM:
  			proto = "tcp";
  			break;
  		default:
  			proto = NULL;
  			break;
  		}
  
  //		sp = getservbyname_r(servname, proto, &sv, svd);
      sp = getservbyname ( servname, proto );
  		if (sp == NULL)
  			return EAI_SERVICE;
  		port = sp->s_port;
  	}
  
  	if (!matchonly) {
  		switch (ai->ai_family) {
  		case AF_INET:
  			((struct sockaddr_in *)(void *)
  			    ai->ai_addr)->sin_port = (in_port_t)port;
  			break;
  #ifdef INET6
  		case AF_INET6:
  			((struct sockaddr_in6 *)(void *)
  			    ai->ai_addr)->sin6_port = (in_port_t)port;
  			break;
  #endif
  		}
  	}
  
  	return 0;
  }
  
  static const struct afd *
  find_afd(int af)
  {
  	const struct afd *afd;
  
  	if (af == PF_UNSPEC)
  		return NULL;
  	for (afd = afdl; afd->a_af; afd++) {
  		if (afd->a_af == af)
  			return afd;
  	}
  	return NULL;
  }
  
  #ifdef INET6
  /* convert a string to a scope identifier. XXX: IPv6 specific */
  static int
  ip6_str2scopeid(char *scope, struct sockaddr_in6 *sin6, u_int32_t *scopeid)
  {
  	u_long lscopeid;
  	struct in6_addr *a6;
  	char *ep;
  
  	_DIAGASSERT(scope != NULL);
  	_DIAGASSERT(sin6 != NULL);
  	_DIAGASSERT(scopeid != NULL);
  
  	a6 = &sin6->sin6_addr;
  
  	/* empty scopeid portion is invalid */
  	if (*scope == '\0')
  		return -1;
  
  	if (IN6_IS_ADDR_LINKLOCAL(a6) || IN6_IS_ADDR_MC_LINKLOCAL(a6)) {
  		/*
  		 * We currently assume a one-to-one mapping between links
  		 * and interfaces, so we simply use interface indices for
  		 * like-local scopes.
  		 */
  /*
  		*scopeid = if_nametoindex(scope);
  		if (*scopeid == 0)
  			goto trynumeric;
  		return 0;
  */
  		return -1;
  	}
  
  	/* still unclear about literal, allow numeric only - placeholder */
  	if (IN6_IS_ADDR_SITELOCAL(a6) || IN6_IS_ADDR_MC_SITELOCAL(a6))
  		goto trynumeric;
  	if (IN6_IS_ADDR_MC_ORGLOCAL(a6))
  		goto trynumeric;
  	else
  		goto trynumeric;	/* global */
  
  	/* try to convert to a numeric id as a last resort */
    trynumeric:
  	errno = 0;
  	lscopeid = strtoul(scope, &ep, 10);
  	*scopeid = (u_int32_t)(lscopeid & 0xffffffffUL);
  	if (errno == 0 && ep && *ep == '\0' && *scopeid == lscopeid)
  		return 0;
  	else
  		return -1;
  }
  #endif
  
  /* code duplicate with gethnamaddr.c */
  
  static struct addrinfo *
  getanswer(const querybuf *answer, int anslen, const char *qname, int qtype,
      const struct addrinfo *pai)
  {
  	struct addrinfo sentinel, *cur;
  	struct addrinfo ai;
  	const struct afd *afd;
  	char *canonname;
  	const HEADER *hp;
  	const u_char *cp;
  	int n;
  	const u_char *eom;
  	char *bp, *ep;
  	int type, class, ancount, qdcount;
  	int haveanswer, had_error;
  	char tbuf[MAXDNAME];
  	int (*name_ok) (const char *);
  	static char hostbuf[8*1024];
  
  	_DIAGASSERT(answer != NULL);
  	_DIAGASSERT(qname != NULL);
  	_DIAGASSERT(pai != NULL);
  
  	memset(&sentinel, 0, sizeof(sentinel));
  	cur = &sentinel;
  
  	canonname = NULL;
  	eom = answer->buf + anslen;
  	switch (qtype) {
  	case T_A:
  	case T_AAAA:
  	case T_ANY:	/*use T_ANY only for T_A/T_AAAA lookup*/
  		name_ok = res_hnok;
  		break;
  	default:
  		return NULL;	/* XXX should be abort(); */
  	}
  	/*
  	 * find first satisfactory answer
  	 */
  	hp = &answer->hdr;
  	ancount = ntohs(hp->ancount);
  	qdcount = ntohs(hp->qdcount);
  	bp = hostbuf;
  	ep = hostbuf + sizeof hostbuf;
  	cp = answer->buf + HFIXEDSZ;
  	if (qdcount != 1) {
  		h_errno = NO_RECOVERY;
  		return (NULL);
  	}
  	n = dn_expand(answer->buf, eom, cp, bp, (int)(ep - bp));
  	if ((n < 0) || !(*name_ok)(bp)) {
  		h_errno = NO_RECOVERY;
  		return (NULL);
  	}
  	cp += n + QFIXEDSZ;
  	if (qtype == T_A || qtype == T_AAAA || qtype == T_ANY) {
  		/* res_send() has already verified that the query name is the
  		 * same as the one we sent; this just gets the expanded name
  		 * (i.e., with the succeeding search-domain tacked on).
  		 */
  		n = (int)strlen(bp) + 1;		/* for the \0 */
  		if (n >= MAXHOSTNAMELEN) {
  			h_errno = NO_RECOVERY;
  			return (NULL);
  		}
  		canonname = bp;
  		bp += n;
  		/* The qname can be abbreviated, but h_name is now absolute. */
  		qname = canonname;
  	}
  	haveanswer = 0;
  	had_error = 0;
  	while (ancount-- > 0 && cp < eom && !had_error) {
  		n = dn_expand(answer->buf, eom, cp, bp, (int)(ep - bp));
  		if ((n < 0) || !(*name_ok)(bp)) {
  			had_error++;
  			continue;
  		}
  		cp += n;			/* name */
  		type = _getshort(cp);
   		cp += INT16SZ;			/* type */
  		class = _getshort(cp);
   		cp += INT16SZ + INT32SZ;	/* class, TTL */
  		n = _getshort(cp);
  		cp += INT16SZ;			/* len */
  		if (class != C_IN) {
  			/* XXX - debug? syslog? */
  			cp += n;
  			continue;		/* XXX - had_error++ ? */
  		}
  		if ((qtype == T_A || qtype == T_AAAA || qtype == T_ANY) &&
  		    type == T_CNAME) {
  			n = dn_expand(answer->buf, eom, cp, tbuf, sizeof tbuf);
  			if ((n < 0) || !(*name_ok)(tbuf)) {
  				had_error++;
  				continue;
  			}
  			cp += n;
  			/* Get canonical name. */
  			n = (int)strlen(tbuf) + 1;	/* for the \0 */
  			if (n > ep - bp || n >= MAXHOSTNAMELEN) {
  				had_error++;
  				continue;
  			}
  			strlcpy(bp, tbuf, (size_t)(ep - bp));
  			canonname = bp;
  			bp += n;
  			continue;
  		}
  		if (qtype == T_ANY) {
  			if (!(type == T_A || type == T_AAAA)) {
  				cp += n;
  				continue;
  			}
  		} else if (type != qtype) {
  			if (type != T_KEY && type != T_SIG) {
  #ifdef _ORG_FREEBSD_
  				struct syslog_data sd = SYSLOG_DATA_INIT;
  				syslog_r(LOG_NOTICE|LOG_AUTH, &sd,
  	       "gethostby*.getanswer: asked for \"%s %s %s\", got type \"%s\"",
  				       qname, p_class(C_IN), p_type(qtype),
  				       p_type(type));
  #endif
  			}
  			cp += n;
  			continue;		/* XXX - had_error++ ? */
  		}
  		switch (type) {
  		case T_A:
  		case T_AAAA:
  			if (strcasecmp(canonname, bp) != 0) {
  #ifdef _ORG_FREEBSD_
  				struct syslog_data sd = SYSLOG_DATA_INIT;
  				syslog_r(LOG_NOTICE|LOG_AUTH, &sd,
  				       AskedForGot, canonname, bp);
  #endif
  				cp += n;
  				continue;	/* XXX - had_error++ ? */
  			}
  			if (type == T_A && n != INADDRSZ) {
  				cp += n;
  				continue;
  			}
  			if (type == T_AAAA && n != IN6ADDRSZ) {
  				cp += n;
  				continue;
  			}
  			if (type == T_AAAA) {
  				struct in6_addr in6;
  				memcpy(&in6, cp, IN6ADDRSZ);
  				if (IN6_IS_ADDR_V4MAPPED(&in6)) {
  					cp += n;
  					continue;
  				}
  			}
  			if (!haveanswer) {
  				int nn;
  
  				canonname = bp;
  				nn = (int)strlen(bp) + 1;	/* for the \0 */
  				bp += nn;
  			}
  
  			/* don't overwrite pai */
  			ai = *pai;
  			ai.ai_family = (type == T_A) ? AF_INET : AF_INET6;
  			afd = find_afd(ai.ai_family);
  			if (afd == NULL) {
  				cp += n;
  				continue;
  			}
  			cur->ai_next = get_ai(&ai, afd, (const char *)cp);
  			if (cur->ai_next == NULL)
  				had_error++;
  			while (cur && cur->ai_next)
  				cur = cur->ai_next;
  			cp += n;
  			break;
  		default:
  			abort();
  		}
  		if (!had_error)
  			haveanswer++;
  	}
  	if (haveanswer) {
  		if (!canonname)
  			(void)get_canonname(pai, sentinel.ai_next, qname);
  		else
  			(void)get_canonname(pai, sentinel.ai_next, canonname);
  		h_errno = NETDB_SUCCESS;
  		return sentinel.ai_next;
  	}
  
  	h_errno = NO_RECOVERY;
  	return NULL;
  }
  
  #define SORTEDADDR(p)	(((struct sockaddr_in *)(void *)(p->ai_next->ai_addr))->sin_addr.s_addr)
  #define SORTMATCH(p, s) ((SORTEDADDR(p) & (s).mask) == (s).addr.s_addr)
  
  static void
  aisort(struct addrinfo *s, res_state res)
  {
  	struct addrinfo head, *t, *p;
  	int i;
  
  	head.ai_next = NULL;
  	t = &head;
  
  	for (i = 0; i < (int)res->nsort; i++) {
  		p = s;
  		while (p->ai_next) {
  			if ((p->ai_next->ai_family != AF_INET)
  			|| SORTMATCH(p, res->sort_list[i])) {
  				t->ai_next = p->ai_next;
  				t = t->ai_next;
  				p->ai_next = p->ai_next->ai_next;
  			} else {
  				p = p->ai_next;
  			}
  		}
  	}
  
  	/* add rest of list and reset s to the new list*/
  	t->ai_next = s->ai_next;
  	s->ai_next = head.ai_next;
  }
  
  /*ARGSUSED*/
  static int
  _dns_getaddrinfo(void *rv, void	*cb_data, va_list ap)
  {
  	struct addrinfo *ai;
  	querybuf *buf, *buf2;
  	const char *name;
  	const struct addrinfo *pai;
  	struct addrinfo sentinel, *cur;
  	struct res_target q, q2;
  	res_state res;
  
  	name = va_arg(ap, char *);
  	pai = va_arg(ap, const struct addrinfo *);
  
  	memset(&q, 0, sizeof(q));
  	memset(&q2, 0, sizeof(q2));
  	memset(&sentinel, 0, sizeof(sentinel));
  	cur = &sentinel;
  
  	buf = malloc(sizeof(*buf));
  	if (buf == NULL) {
  		h_errno = NETDB_INTERNAL;
  		return NS_NOTFOUND;
  	}
  	buf2 = malloc(sizeof(*buf2));
  	if (buf2 == NULL) {
  		free(buf);
  		h_errno = NETDB_INTERNAL;
  		return NS_NOTFOUND;
  	}
  
  	switch (pai->ai_family) {
  	case AF_UNSPEC:
  		/* prefer IPv6 */
  		q.name = name;
  		q.qclass = C_IN;
  		q.qtype = T_AAAA;
  		q.answer = buf->buf;
  		q.anslen = sizeof(buf->buf);
  		q.next = &q2;
  		q2.name = name;
  		q2.qclass = C_IN;
  		q2.qtype = T_A;
  		q2.answer = buf2->buf;
  		q2.anslen = sizeof(buf2->buf);
  		break;
  	case AF_INET:
  		q.name = name;
  		q.qclass = C_IN;
  		q.qtype = T_A;
  		q.answer = buf->buf;
  		q.anslen = sizeof(buf->buf);
  		break;
  	case AF_INET6:
  		q.name = name;
  		q.qclass = C_IN;
  		q.qtype = T_AAAA;
  		q.answer = buf->buf;
  		q.anslen = sizeof(buf->buf);
  		break;
  	default:
  		free(buf);
  		free(buf2);
  		return NS_UNAVAIL;
  	}
  
  	res = __res_get_state();
  	if (res == NULL) {
  		free(buf);
  		free(buf2);
  		return NS_NOTFOUND;
  	}
  
  	if (res_searchN(name, &q, res) < 0) {
  		__res_put_state(res);
  		free(buf);
  		free(buf2);
  		return NS_NOTFOUND;
  	}
  	ai = getanswer(buf, q.n, q.name, q.qtype, pai);
  	if (ai) {
  		cur->ai_next = ai;
  		while (cur && cur->ai_next)
  			cur = cur->ai_next;
  	}
  	if (q.next) {
  		ai = getanswer(buf2, q2.n, q2.name, q2.qtype, pai);
  		if (ai)
  			cur->ai_next = ai;
  	}
  	free(buf);
  	free(buf2);
  	if (sentinel.ai_next == NULL) {
  		__res_put_state(res);
  		switch (h_errno) {
  		case HOST_NOT_FOUND:
  			return NS_NOTFOUND;
  		case TRY_AGAIN:
  			return NS_TRYAGAIN;
  		default:
  			return NS_UNAVAIL;
  		}
  	}
  
  	if (res->nsort)
  		aisort(&sentinel, res);
  
  	__res_put_state(res);
  
  	*((struct addrinfo **)rv) = sentinel.ai_next;
  	return NS_SUCCESS;
  }
  
  static void
  _sethtent(FILE **hostf)
  {
  
  	if (!*hostf)
  		*hostf = fopen(_PATH_HOSTS, "r" );
  	else
  		rewind(*hostf);
  }
  
  static void
  _endhtent(FILE **hostf)
  {
  
  	if (*hostf) {
  		(void) fclose(*hostf);
  		*hostf = NULL;
  	}
  }
  
  static struct addrinfo *
  _gethtent(FILE **hostf, const char *name, const struct addrinfo *pai)
  {
  	char *p;
  	char *cp, *tname, *cname;
  	struct addrinfo hints, *res0, *res;
  	int error;
  	const char *addr;
  	static char hostbuf[8*1024];
  
  	_DIAGASSERT(name != NULL);
  	_DIAGASSERT(pai != NULL);
  
  	if (!*hostf && ( NULL == (*hostf = fopen(_PATH_HOSTS, "r" ))))
  		return (NULL);
   again:
  	if ( NULL == (p = fgets(hostbuf, sizeof hostbuf, *hostf)))
  		return (NULL);
  	if (*p == '#')
  		goto again;
  	if ( NULL == (cp = strpbrk(p, "#\n")))
  		goto again;
  	*cp = '\0';
  	if ( NULL == (cp = strpbrk(p, " \t")))
  		goto again;
  	*cp++ = '\0';
  	addr = p;
  	/* if this is not something we're looking for, skip it. */
  	cname = NULL;
  	while (cp && *cp) {
  		if (*cp == ' ' || *cp == '\t') {
  			cp++;
  			continue;
  		}
  		if (!cname)
  			cname = cp;
  		tname = cp;
  		if ((cp = strpbrk(cp, " \t")) != NULL)
  			*cp++ = '\0';
  		if (strcasecmp(name, tname) == 0)
  			goto found;
  	}
  	goto again;
  
  found:
  	hints = *pai;
  	hints.ai_flags = AI_NUMERICHOST;
  	error = getaddrinfo(addr, NULL, &hints, &res0);
  	if (error)
  		goto again;
  	for (res = res0; res; res = res->ai_next) {
  		/* cover it up */
  		res->ai_flags = pai->ai_flags;
  
  		if (pai->ai_flags & AI_CANONNAME) {
  			if (get_canonname(pai, res, cname) != 0) {
  				freeaddrinfo(res0);
  				goto again;
  			}
  		}
  	}
  	return res0;
  }
  
  /*ARGSUSED*/
  static int
  _files_getaddrinfo(void *rv, void *cb_data, va_list ap)
  {
  	const char *name;
  	const struct addrinfo *pai;
  	struct addrinfo sentinel, *cur;
  	struct addrinfo *p;
  #ifndef _REENTRANT
  	static
  #endif
  	FILE *hostf = NULL;
  
  	name = va_arg(ap, char *);
  	pai = va_arg(ap, const struct addrinfo *);
  
  	memset(&sentinel, 0, sizeof(sentinel));
  	cur = &sentinel;
  
  	_sethtent(&hostf);
  	while ((p = _gethtent(&hostf, name, pai)) != NULL) {
  		cur->ai_next = p;
  		while (cur && cur->ai_next)
  			cur = cur->ai_next;
  	}
  	_endhtent(&hostf);
  
  	*((struct addrinfo **)rv) = sentinel.ai_next;
  	if (sentinel.ai_next == NULL)
  		return NS_NOTFOUND;
  	return NS_SUCCESS;
  }
  
  #ifdef YP
  /*ARGSUSED*/
  static struct addrinfo *
  _yphostent(char *line, const struct addrinfo *pai)
  {
  	struct addrinfo sentinel, *cur;
  	struct addrinfo hints, *res, *res0;
  	int error;
  	char *p;
  	const char *addr, *canonname;
  	char *nextline;
  	char *cp;
  
  	_DIAGASSERT(line != NULL);
  	_DIAGASSERT(pai != NULL);
  
  	p = line;
  	addr = canonname = NULL;
  
  	memset(&sentinel, 0, sizeof(sentinel));
  	cur = &sentinel;
  
  nextline:
  	/* terminate line */
  	cp = strchr(p, '\n');
  	if (cp) {
  		*cp++ = '\0';
  		nextline = cp;
  	} else
  		nextline = NULL;
  
  	cp = strpbrk(p, " \t");
  	if (cp == NULL) {
  		if (canonname == NULL)
  			return (NULL);
  		else
  			goto done;
  	}
  	*cp++ = '\0';
  
  	addr = p;
  
  	while (cp && *cp) {
  		if (*cp == ' ' || *cp == '\t') {
  			cp++;
  			continue;
  		}
  		if (!canonname)
  			canonname = cp;
  		if ((cp = strpbrk(cp, " \t")) != NULL)
  			*cp++ = '\0';
  	}
  
  	hints = *pai;
  	hints.ai_flags = AI_NUMERICHOST;
  	error = getaddrinfo(addr, NULL, &hints, &res0);
  	if (error == 0) {
  		for (res = res0; res; res = res->ai_next) {
  			/* cover it up */
  			res->ai_flags = pai->ai_flags;
  
  			if (pai->ai_flags & AI_CANONNAME)
  				(void)get_canonname(pai, res, canonname);
  		}
  	} else
  		res0 = NULL;
  	if (res0) {
  		cur->ai_next = res0;
  		while (cur->ai_next)
  			cur = cur->ai_next;
  	}
  
  	if (nextline) {
  		p = nextline;
  		goto nextline;
  	}
  
  done:
  	return sentinel.ai_next;
  }
  
  /*ARGSUSED*/
  static int
  _yp_getaddrinfo(void *rv, void *cb_data, va_list ap)
  {
  	struct addrinfo sentinel, *cur;
  	struct addrinfo *ai = NULL;
  	char *ypbuf;
  	int ypbuflen, r;
  	const char *name;
  	const struct addrinfo *pai;
  	char *ypdomain;
  
  	if (_yp_check(&ypdomain) == 0)
  		return NS_UNAVAIL;
  
  	name = va_arg(ap, char *);
  	pai = va_arg(ap, const struct addrinfo *);
  
  	memset(&sentinel, 0, sizeof(sentinel));
  	cur = &sentinel;
  
  	/* hosts.byname is only for IPv4 (Solaris8) */
  	if (pai->ai_family == PF_UNSPEC || pai->ai_family == PF_INET) {
  		r = yp_match(ypdomain, "hosts.byname", name,
  			(int)strlen(name), &ypbuf, &ypbuflen);
  		if (r == 0) {
  			struct addrinfo ai4;
  
  			ai4 = *pai;
  			ai4.ai_family = AF_INET;
  			ai = _yphostent(ypbuf, &ai4);
  			if (ai) {
  				cur->ai_next = ai;
  				while (cur && cur->ai_next)
  					cur = cur->ai_next;
  			}
  		}
  		free(ypbuf);
  	}
  
  	/* ipnodes.byname can hold both IPv4/v6 */
  	r = yp_match(ypdomain, "ipnodes.byname", name,
  		(int)strlen(name), &ypbuf, &ypbuflen);
  	if (r == 0) {
  		ai = _yphostent(ypbuf, pai);
  		if (ai)
  			cur->ai_next = ai;
  		free(ypbuf);
  	}
  
  	if (sentinel.ai_next == NULL) {
  		h_errno = HOST_NOT_FOUND;
  		return NS_NOTFOUND;
  	}
  	*((struct addrinfo **)rv) = sentinel.ai_next;
  	return NS_SUCCESS;
  }
  #endif
  
  /* resolver logic */
  
  /*
   * 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.
   */
  static int
  res_queryN(const char *name, /* domain name */ struct res_target *target,
      res_state res)
  {
  	static u_char buf[MAXPACKET];
  	HEADER *hp;
  	int n;
  	struct res_target *t;
  	int rcode;
  	int ancount;
  
  	_DIAGASSERT(name != NULL);
  	/* XXX: target may be NULL??? */
  
  	rcode = NOERROR;
  	ancount = 0;
  
  	for (t = target; t; t = t->next) {
  		int class, type;
  		u_char *answer;
  		int anslen;
  
  		hp = (HEADER *)(void *)t->answer;
  		hp->rcode = NOERROR;	/* default */
  
  		/* make it easier... */
  		class = t->qclass;
  		type = t->qtype;
  		answer = t->answer;
  		anslen = t->anslen;
  #ifdef DEBUG
  		if (res->options & RES_DEBUG)
  			printf(";; res_nquery(%s, %d, %d)\n", name, class, type);
  #endif
  
  		n = res_nmkquery(res, QUERY, name, class, type, NULL, 0, NULL,
  		    buf, sizeof(buf));
  #ifdef RES_USE_EDNS0
  		if (n > 0 && (res->options & RES_USE_EDNS0) != 0)
  			n = res_nopt(res, n, buf, sizeof(buf), anslen);
  #endif
  		if (n <= 0) {
  #ifdef DEBUG
  			if (res->options & RES_DEBUG)
  				printf(";; res_nquery: mkquery failed\n");
  #endif
  			h_errno = NO_RECOVERY;
  			return n;
  		}
  		n = res_nsend(res, buf, n, answer, anslen);
  #if 0
  		if (n < 0) {
  #ifdef DEBUG
  			if (res->options & RES_DEBUG)
  				printf(";; res_query: send error\n");
  #endif
  			h_errno = TRY_AGAIN;
  			return n;
  		}
  #endif
  
  		if (n < 0 || hp->rcode != NOERROR || ntohs(hp->ancount) == 0) {
  			rcode = hp->rcode;	/* record most recent error */
  #ifdef DEBUG
  			if (res->options & RES_DEBUG)
  				printf(";; rcode = %u, ancount=%u\n", hp->rcode,
  				    ntohs(hp->ancount));
  #endif
  			continue;
  		}
  
  		ancount += ntohs(hp->ancount);
  
  		t->n = n;
  	}
  
  	if (ancount == 0) {
  		switch (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 ancount;
  }
  
  /*
   * 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.
   */
  static int
  res_searchN(const char *name, struct res_target *target, res_state res)
  {
  	const char *cp, * const *domain;
  	HEADER *hp;
  	u_int dots;
  	int trailing_dot, ret, saved_herrno;
  	int got_nodata = 0, got_servfail = 0, tried_as_is = 0;
  
  	_DIAGASSERT(name != NULL);
  	_DIAGASSERT(target != NULL);
  
  	hp = (HEADER *)(void *)target->answer;	/*XXX*/
  
  	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) {
  		ret = res_queryN(cp, target, res);
  		return ret;
  	}
  
  	/*
  	 * 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_querydomainN(name, NULL, target, res);
  		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_querydomainN(name, *domain, target, res);
  			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_querydomainN(name, NULL, target, res);
  		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.
   */
  static int
  res_querydomainN(const char *name, const char *domain,
      struct res_target *target, res_state res)
  {
  	char nbuf[MAXDNAME];
  	const char *longname = nbuf;
  	size_t n, d;
  
  	_DIAGASSERT(name != NULL);
  	/* XXX: target may be NULL??? */
  
  #ifdef DEBUG
  	if (res->options & RES_DEBUG)
  		printf(";; res_querydomain(%s, %s)\n",
  			name, domain?domain:"<Nil>");
  #endif
  	if (domain == NULL) {
  		/*
  		 * Check for trailing '.';
  		 * copy without '.' if present.
  		 */
  		n = strlen(name);
  		if (n + 1 > sizeof(nbuf)) {
  			h_errno = NO_RECOVERY;
  			return -1;
  		}
  		if (n > 0 && name[--n] == '.') {
  			strncpy(nbuf, name, n);
  			nbuf[n] = '\0';
  		} else
  			longname = name;
  	} else {
  		n = strlen(name);
  		d = strlen(domain);
  		if (n + 1 + d + 1 > sizeof(nbuf)) {
  			h_errno = NO_RECOVERY;
  			return -1;
  		}
  		snprintf(nbuf, sizeof(nbuf), "%s.%s", name, domain);
  	}
  	return res_queryN(longname, target, res);
  }
  