/*      $NetBSD: getaddrinfo.c,v 1.119.2.1 2020/11/29 11:25:31 martin 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 1.119.2.1 2020/11/29 11:25:31 martin Exp $");
#endif /* LIBC_SCCS and not lint */
#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 <ifaddrs.h>

#include <syslog.h>
#include <stdarg.h>

#ifdef YP
#include <rpc/rpc.h>
#include <rpcsvc/yp_prot.h>
#include <rpcsvc/ypclnt.h>
#endif

#include <FindDirectory.h>

#include "netdb_private.h"
#include "nsswitch.h"
#include "servent.h"
#include <libutil.h>

#ifndef RUMP_ACTION
#ifdef __weak_alias
__weak_alias(getaddrinfo,_getaddrinfo)
__weak_alias(allocaddrinfo,_allocaddrinfo)
__weak_alias(freeaddrinfo,_freeaddrinfo)
__weak_alias(gai_strerror,_gai_strerror)
#endif
#endif

#define SUCCESS 0
#define ANY 0
#define YES 1
#define NO  0

#define sa4addr(sa) ((void *)&((struct sockaddr_in *)(void *)sa)->sin_addr)
#define sa6addr(sa) ((void *)&((struct sockaddr_in6 *)(void *)sa)->sin6_addr)

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

struct policyqueue {
        TAILQ_ENTRY(policyqueue) pc_entry;
#if defined(INET6) && !defined(__HAIKU__)
        struct in6_addrpolicy pc_policy;
#endif
};
TAILQ_HEAD(policyhead, policyqueue);

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
#define N_INET6 0
        {PF_INET6, sizeof(struct in6_addr), sizeof(struct sockaddr_in6),
                offsetof(struct sockaddr_in6, sin6_addr), in6_addrany, in6_loopback, 1},
#define N_INET 1
#define N_LOCAL 2
#else
#define N_INET 0
#define N_LOCAL 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

#define AIO_SRCFLAG_DEPRECATED  0x1

struct ai_order {
        union {
                struct sockaddr_storage aiou_ss;
                struct sockaddr aiou_sa;
        } aio_src_un;
#define aio_srcsa aio_src_un.aiou_sa
        u_int32_t aio_srcflag;
        int aio_srcscope;
        int aio_dstscope;
        struct policyqueue *aio_srcpolicy;
        struct policyqueue *aio_dstpolicy;
        struct addrinfo *aio_ai;
        int aio_matchlen;
};

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 */
};

struct srvinfo {
       struct srvinfo *next;
       char name[MAXDNAME];
       int port, pri, weight;
};

static int gai_srvok(const char *);
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);
static int addrconfig(uint64_t *);
static void set_source(struct ai_order *, struct policyhead *,
    struct servent_data *);
static int comp_dst(const void *, const void *);
#ifdef INET6
static int ip6_str2scopeid(char *, struct sockaddr_in6 *, u_int32_t *);
#endif
static int gai_addr2scopetype(struct sockaddr *);

static int reorder(struct addrinfo *, struct servent_data *);
static int get_addrselectpolicy(struct policyhead *);
static void free_addrselectpolicy(struct policyhead *);
static struct policyqueue *match_addrselectpolicy(struct sockaddr *,
        struct policyhead *);
static int matchlen(struct sockaddr *, struct sockaddr *);

static struct addrinfo *getanswer(res_state, const querybuf *, int,
    const char *, int, const struct addrinfo *);
static void aisort(struct addrinfo *s, res_state res);
static struct addrinfo * _dns_query(struct res_target *,
    const struct addrinfo *, res_state, int);
static struct addrinfo * _dns_srv_lookup(const char *, const char *,
    const struct addrinfo *);
static struct addrinfo * _dns_host_lookup(const char *,
    const struct addrinfo *);
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 or servname not 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)))

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);
}

/*
 * We don't want localization to affect us
 */
#define PERIOD '.'
#define hyphenchar(c) ((c) == '-')
#define periodchar(c) ((c) == PERIOD)
#define underschar(c) ((c) == '_')
#define alphachar(c) (((c) >= 'a' && (c) <= 'z') || ((c) >= 'A' && (c) <= 'Z'))
#define digitchar(c) ((c) >= '0' && (c) <= '9')

#define firstchar(c)  (alphachar(c) || digitchar(c) || underschar(c))
#define lastchar(c)   (alphachar(c) || digitchar(c))
#define middlechar(c) (lastchar(c) || hyphenchar(c))

static int
gai_srvok(const char *dn)
{
        int nch, pch, ch;

        for (pch = PERIOD, nch = ch = *dn++; ch != '\0'; pch = ch, ch = nch) {
                if (periodchar(ch))
                        continue;
                if (periodchar(pch)) {
                        if (!firstchar(ch))
                                return 0;
                } else if (periodchar(nch) || nch == '\0') {
                        if (!lastchar(ch))
                                return 0;
                } else if (!middlechar(ch))
                        return 0;
       }
       return 1;
}

static in_port_t *
getport(struct addrinfo *ai) {
        static in_port_t p;

        switch (ai->ai_family) {
        case AF_INET:
                return &((struct sockaddr_in *)(void *)ai->ai_addr)->sin_port;
#ifdef INET6
        case AF_INET6:
                return &((struct sockaddr_in6 *)(void *)ai->ai_addr)->sin6_port;
#endif
        default:
                p = 0;
                /* XXX: abort()? */
                return &p;
        }
}

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 <= INT_MAX)
                return (int)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;
        uint64_t mask = (uint64_t)~0ULL;
        int numeric = 0;

        /* 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);
                                }
                        }
                }
        }

        /*
         * RFC 3493: AI_ALL and AI_V4MAPPED are effective only against
         * AF_INET6 query.  They need to be ignored if specified in other
         * occassions.
         */
        switch (pai->ai_flags & (AI_ALL | AI_V4MAPPED)) {
                case AI_V4MAPPED:
                case AI_ALL | AI_V4MAPPED:
#ifdef INET6
                        if (pai->ai_family != AF_INET6)
                                pai->ai_flags &= ~(AI_ALL | AI_V4MAPPED);
                        break;
#endif
                case AI_ALL:
                        pai->ai_flags &= ~(AI_ALL | AI_V4MAPPED);
                        break;
        }

        if ((pai->ai_flags & AI_ADDRCONFIG) != 0 && addrconfig(&mask) == -1)
                ERR(EAI_FAIL);

        /*
         * 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)
                        goto bad;

                *pai = ai0;
        }

        ai0 = *pai;

        /* NULL hostname, or numeric hostname */
        for (ex = explore; ex->e_af >= 0; ex++) {
                *pai = ai0;

                /* ADDRCONFIG check */
                if ((((uint64_t)1 << ex->e_af) & mask) == 0)
                        continue;

                /* 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) {
                numeric = 1;
                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;


                /* ADDRCONFIG check */
                /* PF_UNSPEC entries are prepared for DNS queries only */
                if (ex->e_af != PF_UNSPEC &&
                    (((uint64_t)1 << ex->e_af) & mask) == 0)
                        continue;

                /* 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);

#ifndef __HAIKU__
                while (cur && cur->ai_next)
                        cur = cur->ai_next;
#else
                while (cur && cur->ai_next) {
                        if ((((uint64_t)1 << cur->ai_next->ai_family) & mask) == 0) {
                                /* entry does not match addrconfig mask, remove from list */
                                struct addrinfo* removed = cur->ai_next;
                                cur->ai_next = removed->ai_next;
                                removed->ai_next = NULL;
                                freeaddrinfo(removed);
                        } else {
                                /* entry does match, keep it in list and move to next one */
                                cur = cur->ai_next;
                        }
                }
#endif
        }

        /* XXX */
        if (sentinel.ai_next)
                error = 0;

        if (error)
                goto free;

        if (sentinel.ai_next) {
 good:
                /*
                 * If the returned entry is for an active connection,
                 * and the given name is not numeric, reorder the
                 * list, so that the application would try the list
                 * in the most efficient order.  Since the head entry
                 * of the original list may contain ai_canonname and
                 * that entry may be moved elsewhere in the new list,
                 * we keep the pointer and will  restore it in the new
                 * head entry.  (Note that RFC3493 requires the head
                 * entry store it when requested by the caller).
                 */
                if (hints == NULL || !(hints->ai_flags & AI_PASSIVE)) {
                        if (!numeric) {
                                char *canonname;

                                canonname = sentinel.ai_next->ai_canonname;
                                sentinel.ai_next->ai_canonname = NULL;
                                (void)reorder(&sentinel, &svd);
                                if (sentinel.ai_next->ai_canonname == NULL) {
                                        sentinel.ai_next->ai_canonname
                                            = canonname;
                                } else if (canonname != NULL)
                                        free(canonname);
                        }
                }
                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 int
reorder(struct addrinfo *sentinel, struct servent_data *svd)
{
        struct addrinfo *ai, **aip;
        struct ai_order *aio;
        int i, n;
        struct policyhead policyhead;

        /* count the number of addrinfo elements for sorting. */
        for (n = 0, ai = sentinel->ai_next; ai != NULL; ai = ai->ai_next, n++)
                ;

        /*
         * If the number is small enough, we can skip the reordering process.
         */
        if (n <= 1)
                return n;

        /* allocate a temporary array for sort and initialization of it. */
        if ((aio = malloc(sizeof(*aio) * n)) == NULL)
                return n;       /* give up reordering */
        memset(aio, 0, sizeof(*aio) * n);

        /* retrieve address selection policy from the kernel */
        TAILQ_INIT(&policyhead);
        if (!get_addrselectpolicy(&policyhead)) {
                /* no policy is installed into kernel, we don't sort. */
                free(aio);
                return n;
        }

        for (i = 0, ai = sentinel->ai_next; i < n; ai = ai->ai_next, i++) {
                aio[i].aio_ai = ai;
                aio[i].aio_dstscope = gai_addr2scopetype(ai->ai_addr);
                aio[i].aio_dstpolicy = match_addrselectpolicy(ai->ai_addr,
                                                              &policyhead);
                set_source(&aio[i], &policyhead, svd);
        }

        /* perform sorting. */
        qsort(aio, n, sizeof(*aio), comp_dst);

        /* reorder the addrinfo chain. */
        for (i = 0, aip = &sentinel->ai_next; i < n; i++) {
                *aip = aio[i].aio_ai;
                aip = &aio[i].aio_ai->ai_next;
        }
        *aip = NULL;

        /* cleanup and return */
        free(aio);
        free_addrselectpolicy(&policyhead);
        return n;
}

static int
get_addrselectpolicy(struct policyhead *head)
{
#if defined(INET6) && !defined(__HAIKU__)
        static const int mib[] = { 
            CTL_NET, PF_INET6, IPPROTO_IPV6, IPV6CTL_ADDRCTLPOLICY };
        static const u_int miblen = (u_int)__arraycount(mib);
        size_t l;
        char *buf;
        struct in6_addrpolicy *pol, *ep;

        if (sysctl(mib, miblen, NULL, &l, NULL, 0) < 0)
                return 0;
        if (l == 0)
                return 0;
        if ((buf = malloc(l)) == NULL)
                return 0;
        if (sysctl(mib, miblen, buf, &l, NULL, 0) < 0) {
                free(buf);
                return 0;
        }

        ep = (void *)(buf + l);
        for (pol = (void *)buf; pol + 1 <= ep; pol++) {
                struct policyqueue *new;

                if ((new = malloc(sizeof(*new))) == NULL) {
                        free_addrselectpolicy(head); /* make the list empty */
                        break;
                }
                new->pc_policy = *pol;
                TAILQ_INSERT_TAIL(head, new, pc_entry);
        }

        free(buf);
        return 1;
#else
        return 0;
#endif
}

static void
free_addrselectpolicy(struct policyhead *head)
{
        struct policyqueue *ent, *nent;

        for (ent = TAILQ_FIRST(head); ent; ent = nent) {
                nent = TAILQ_NEXT(ent, pc_entry);
                TAILQ_REMOVE(head, ent, pc_entry);
                free(ent);
        }
}

static struct policyqueue *
match_addrselectpolicy(struct sockaddr *addr, struct policyhead *head)
{
#if defined(INET6) && !defined(__HAIKU__)
        struct policyqueue *ent, *bestent = NULL;
        struct in6_addrpolicy *pol;
        int curmatchlen, bestmatchlen = -1;
        u_char *mp, *ep, *k, *p;
        u_int m;
        struct sockaddr_in6 key;

        switch(addr->sa_family) {
        case AF_INET6:
                memcpy(&key, addr, sizeof(key));
                break;
        case AF_INET:
                /* convert the address into IPv4-mapped IPv6 address. */
                memset(&key, 0, sizeof(key));
                key.sin6_family = AF_INET6;
                key.sin6_len = sizeof(key);
                key.sin6_addr.s6_addr[10] = 0xff;
                key.sin6_addr.s6_addr[11] = 0xff;
                memcpy(&key.sin6_addr.s6_addr[12], sa4addr(addr), 4);
                break;
        default:
                return NULL;
        }

        for (ent = TAILQ_FIRST(head); ent; ent = TAILQ_NEXT(ent, pc_entry)) {
                pol = &ent->pc_policy;
                curmatchlen = 0;

                mp = (void *)&pol->addrmask.sin6_addr;
                ep = mp + 16;   /* XXX: scope field? */
                k = (void *)&key.sin6_addr;
                p = (void *)&pol->addr.sin6_addr;
                for (; mp < ep && *mp; mp++, k++, p++) {
                        m = *mp;
                        if ((*k & m) != *p)
                                goto next; /* not match */
                        if (m == 0xff) /* short cut for a typical case */
                                curmatchlen += 8;
                        else {
                                while (m >= 0x80) {
                                        curmatchlen++;
                                        m <<= 1;
                                }
                        }
                }

                /* matched.  check if this is better than the current best. */
                if (curmatchlen > bestmatchlen) {
                        bestent = ent;
                        bestmatchlen = curmatchlen;
                }

          next:
                continue;
        }

        return bestent;
#else
        return NULL;
#endif

}

static void
set_source(struct ai_order *aio, struct policyhead *ph,
    struct servent_data *svd)
{
        struct addrinfo ai = *aio->aio_ai;
        struct sockaddr_storage ss;
        socklen_t srclen;
        int s;

        /* set unspec ("no source is available"), just in case */
        aio->aio_srcsa.sa_family = AF_UNSPEC;
        aio->aio_srcscope = -1;

        switch(ai.ai_family) {
        case AF_INET:
#ifdef INET6
        case AF_INET6:
#endif
                break;
        default:                /* ignore unsupported AFs explicitly */
                return;
        }

        /* XXX: make a dummy addrinfo to call connect() */
        ai.ai_socktype = SOCK_DGRAM;
        ai.ai_protocol = IPPROTO_UDP; /* is UDP too specific? */
        ai.ai_next = NULL;
        memset(&ss, 0, sizeof(ss));
        memcpy(&ss, ai.ai_addr, ai.ai_addrlen);
        ai.ai_addr = (void *)&ss;
        get_port(&ai, "1", 0, svd);

#ifndef SOCK_CLOEXEC
#define SOCK_CLOEXEC 0
#endif

        /* open a socket to get the source address for the given dst */
        if ((s = socket(ai.ai_family, ai.ai_socktype | SOCK_CLOEXEC,
            ai.ai_protocol)) < 0)
                return;         /* give up */

#ifdef INET6
        if (ai.ai_family == AF_INET6) {
                struct sockaddr_in6* sin6 = (struct sockaddr_in6*)ai.ai_addr;
                int off = 0;

                if (IN6_IS_ADDR_V4MAPPED(&sin6->sin6_addr))
                        (void)setsockopt(s, IPPROTO_IPV6, IPV6_V6ONLY, (char*)&off, sizeof(off));
        }
#endif

#if SOCK_CLOEXEC == 0
        fcntl(s, F_SETFD, FD_CLOEXEC);
#endif
        if (connect(s, ai.ai_addr, ai.ai_addrlen) < 0)
                goto cleanup;
        srclen = ai.ai_addrlen;
        if (getsockname(s, &aio->aio_srcsa, &srclen) < 0) {
                aio->aio_srcsa.sa_family = AF_UNSPEC;
                goto cleanup;
        }
        aio->aio_srcscope = gai_addr2scopetype(&aio->aio_srcsa);
        aio->aio_srcpolicy = match_addrselectpolicy(&aio->aio_srcsa, ph);
        aio->aio_matchlen = matchlen(&aio->aio_srcsa, aio->aio_ai->ai_addr);
#if defined(INET6) && !defined(__HAIKU__)
        if (ai.ai_family == AF_INET6) {
                struct in6_ifreq ifr6;
                u_int32_t flags6;

                memset(&ifr6, 0, sizeof(ifr6));
                memcpy(&ifr6.ifr_addr, ai.ai_addr, ai.ai_addrlen);
                if (ioctl(s, SIOCGIFAFLAG_IN6, &ifr6) == 0) {
                        flags6 = ifr6.ifr_ifru.ifru_flags6;
                        if ((flags6 & IN6_IFF_DEPRECATED))
                                aio->aio_srcflag |= AIO_SRCFLAG_DEPRECATED;
                }
        }
#endif

  cleanup:
        close(s);
        return;
}

static int
matchlen(struct sockaddr *src, struct sockaddr *dst)
{
        int match = 0;
        u_char *s, *d;
        u_char *lim;
        u_int r, addrlen;

        switch (src->sa_family) {
#ifdef INET6
        case AF_INET6:
                s = sa6addr(src);
                d = sa6addr(dst);
                addrlen = sizeof(struct in6_addr);
                lim = s + addrlen;
                break;
#endif
        case AF_INET:
                s = sa4addr(src);
                d = sa4addr(dst);
                addrlen = sizeof(struct in_addr);
                lim = s + addrlen;
                break;
        default:
                return 0;
        }

        while (s < lim)
                if ((r = (*d++ ^ *s++)) != 0) {
                        while (r < addrlen * 8) {
                                match++;
                                r <<= 1;
                        }
                        break;
                } else
                        match += 8;
        return match;
}

static int
comp_dst(const void *arg1, const void *arg2)
{
        const struct ai_order *dst1 = arg1, *dst2 = arg2;

        /*
         * Rule 1: Avoid unusable destinations.
         * XXX: we currently do not consider if an appropriate route exists.
         */
        if (dst1->aio_srcsa.sa_family != AF_UNSPEC &&
            dst2->aio_srcsa.sa_family == AF_UNSPEC) {
                return -1;
        }
        if (dst1->aio_srcsa.sa_family == AF_UNSPEC &&
            dst2->aio_srcsa.sa_family != AF_UNSPEC) {
                return 1;
        }

        /* Rule 2: Prefer matching scope. */
        if (dst1->aio_dstscope == dst1->aio_srcscope &&
            dst2->aio_dstscope != dst2->aio_srcscope) {
                return -1;
        }
        if (dst1->aio_dstscope != dst1->aio_srcscope &&
            dst2->aio_dstscope == dst2->aio_srcscope) {
                return 1;
        }

        /* Rule 3: Avoid deprecated addresses. */
        if (dst1->aio_srcsa.sa_family != AF_UNSPEC &&
            dst2->aio_srcsa.sa_family != AF_UNSPEC) {
                if (!(dst1->aio_srcflag & AIO_SRCFLAG_DEPRECATED) &&
                    (dst2->aio_srcflag & AIO_SRCFLAG_DEPRECATED)) {
                        return -1;
                }
                if ((dst1->aio_srcflag & AIO_SRCFLAG_DEPRECATED) &&
                    !(dst2->aio_srcflag & AIO_SRCFLAG_DEPRECATED)) {
                        return 1;
                }
        }

        /* Rule 4: Prefer home addresses. */
        /* XXX: not implemented yet */

        /* Rule 5: Prefer matching label. */
#if defined(INET6) && !defined(__HAIKU__)
        if (dst1->aio_srcpolicy && dst1->aio_dstpolicy &&
            dst1->aio_srcpolicy->pc_policy.label ==
            dst1->aio_dstpolicy->pc_policy.label &&
            (dst2->aio_srcpolicy == NULL || dst2->aio_dstpolicy == NULL ||
             dst2->aio_srcpolicy->pc_policy.label !=
             dst2->aio_dstpolicy->pc_policy.label)) {
                return -1;
        }
        if (dst2->aio_srcpolicy && dst2->aio_dstpolicy &&
            dst2->aio_srcpolicy->pc_policy.label ==
            dst2->aio_dstpolicy->pc_policy.label &&
            (dst1->aio_srcpolicy == NULL || dst1->aio_dstpolicy == NULL ||
             dst1->aio_srcpolicy->pc_policy.label !=
             dst1->aio_dstpolicy->pc_policy.label)) {
                return 1;
        }
#endif

        /* Rule 6: Prefer higher precedence. */
#if defined(INET6) && !defined(__HAIKU__)
        if (dst1->aio_dstpolicy &&
            (dst2->aio_dstpolicy == NULL ||
             dst1->aio_dstpolicy->pc_policy.preced >
             dst2->aio_dstpolicy->pc_policy.preced)) {
                return -1;
        }
        if (dst2->aio_dstpolicy &&
            (dst1->aio_dstpolicy == NULL ||
             dst2->aio_dstpolicy->pc_policy.preced >
             dst1->aio_dstpolicy->pc_policy.preced)) {
                return 1;
        }
#endif

        /* Rule 7: Prefer native transport. */
        /* XXX: not implemented yet */

        /* Rule 8: Prefer smaller scope. */
        if (dst1->aio_dstscope >= 0 &&
            dst1->aio_dstscope < dst2->aio_dstscope) {
                return -1;
        }
        if (dst2->aio_dstscope >= 0 &&
            dst2->aio_dstscope < dst1->aio_dstscope) {
                return 1;
        }

        /*
         * Rule 9: Use longest matching prefix.
         * We compare the match length in a same AF only.
         */
        if (dst1->aio_ai->ai_addr->sa_family ==
            dst2->aio_ai->ai_addr->sa_family &&
            dst1->aio_ai->ai_addr->sa_family != AF_INET) {
                if (dst1->aio_matchlen > dst2->aio_matchlen) {
                        return -1;
                }
                if (dst1->aio_matchlen < dst2->aio_matchlen) {
                        return 1;
                }
        }

        /* Rule 10: Otherwise, leave the order unchanged. */
        return -1;
}

/*
 * Copy from scope.c.
 * XXX: we should standardize the functions and link them as standard
 * library.
 */
static int
gai_addr2scopetype(struct sockaddr *sa)
{
#ifdef INET6
        struct sockaddr_in6 *sa6;
#endif
        struct sockaddr_in *sa4;
        u_char *p;

        switch(sa->sa_family) {
#ifdef INET6
        case AF_INET6:
                sa6 = (void *)sa;
                if (IN6_IS_ADDR_MULTICAST(&sa6->sin6_addr)) {
                        /* just use the scope field of the multicast address */
                        return sa6->sin6_addr.s6_addr[2] & 0x0f;
                }
                /*
                 * Unicast addresses: map scope type to corresponding scope
                 * value defined for multcast addresses.
                 * XXX: hardcoded scope type values are bad...
                 */
                if (IN6_IS_ADDR_LOOPBACK(&sa6->sin6_addr))
                        return 1; /* node local scope */
                if (IN6_IS_ADDR_LINKLOCAL(&sa6->sin6_addr))
                        return 2; /* link-local scope */
                if (IN6_IS_ADDR_SITELOCAL(&sa6->sin6_addr))
                        return 5; /* site-local scope */
                return 14;      /* global scope */
#endif
        case AF_INET:
                /*
                 * IPv4 pseudo scoping according to RFC 3484.
                 */
                sa4 = (void *)sa;
                p = (u_char *)(void *)&sa4->sin_addr;
                /* IPv4 autoconfiguration addresses have link-local scope. */
                if (p[0] == 169 && p[1] == 254)
                        return 2;
                /* Private addresses have site-local scope. */
                if (p[0] == 10 ||
                    (p[0] == 172 && (p[1] & 0xf0) == 16) ||
                    (p[0] == 192 && p[1] == 168))
                        return 14;      /* XXX: It should be 5 unless NAT */
                /* Loopback addresses have link-local scope. */
                if (p[0] == 127)
                        return 2;
                return 14;
        default:
                errno = EAFNOSUPPORT; /* is this a good error? */
                return -1;
        }
}

/*
 * 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;
        static const ns_dtab dtab[] = {
                NS_FILES_CB(_files_getaddrinfo, NULL)
                { NSSRC_DNS, _dns_getaddrinfo, NULL },  /* force -DHESIOD */
                NS_NIS_CB(_yp_getaddrinfo, NULL)
                NS_NULL_CB
        };

        _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, servname)) {
        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) {
                        /* Check for already filled port. */
                        if (*getport(cur))
                                continue;
                        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, ai0;
        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) {
        case AF_INET:
               /*
                * RFC3493 section 6.1, requires getaddrinfo() to accept
                * AF_INET formats that are accepted by inet_addr(); here
                * we use the equivalent inet_aton() function so we can
                * check for errors. inet_pton() only accepts addresses
                * in the dotted quad format and only in base 10, so we
                * need to treat AF_INET specially.
                *
                * We also check for trailing characters and fail if there
                * are any. This matches the inet_pton6(), but not the
                * inet_pton4() behavior. We choose to make the protocol
                * behavior consistent.
                */
                   if (inet_aton(hostname, (void*)pton) != 1
                           || hostname[strspn(hostname, "0123456789.xabcdefXABCDEF")] != '\0') {
                           return 0;
                   }
                break;
        default:
                if (inet_pton(afd->a_af, hostname, pton) != 1) {
                        if (pai->ai_family != AF_INET6 || (pai->ai_flags & AI_V4MAPPED) != AI_V4MAPPED)
                                return 0;
                        if (inet_aton(hostname, (struct in_addr*)pton) != 1)
                                return 0;
                        afd = &afdl[N_INET];
                        ai0 = *pai;
                        ai0.ai_family = AF_INET;
                        pai = &ai0;
                }
                break;
        }

        if (pai->ai_family == afd->a_af) {
                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 RFC3493.
                         */
                        GET_CANONNAME(cur->ai_next, canonname);
                }
                while (cur->ai_next)
                        cur = cur->ai_next;
        } else {
                ERR(EAI_FAMILY); /*xxx*/
        }

        *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;
}

struct addrinfo *
allocaddrinfo(socklen_t addrlen)
{
        struct addrinfo *ai;

        ai = calloc(sizeof(struct addrinfo) + addrlen, 1);
        if (ai) {
                ai->ai_addr = (void *)(ai+1);
                ai->ai_addrlen = ai->ai_addr->sa_len = addrlen;
        }

        return ai;
}


static struct addrinfo *
get_ai(const struct addrinfo *pai, const struct afd *afd, const char *addr)
{
        char *p;
        struct addrinfo *ai;
        struct sockaddr *save;

#ifdef INET6
        struct in6_addr mapaddr;
#endif

        _DIAGASSERT(pai != NULL);
        _DIAGASSERT(afd != NULL);
        _DIAGASSERT(addr != NULL);

#ifdef INET6
        if (afd->a_af == AF_INET && (pai->ai_flags & AI_V4MAPPED) != 0) {
                afd = &afdl[N_INET6];
                _map_v4v6_address(addr, (char*)&mapaddr);
                addr = (char*)&mapaddr;
        }
#endif

        ai = allocaddrinfo((socklen_t)afd->a_socklen);
        if (ai == NULL)
                return NULL;

        save = ai->ai_addr;
        memcpy(ai, pai, sizeof(struct addrinfo));

        /* since we just overwrote all of ai, we have
           to restore ai_addr and ai_addrlen */
        ai->ai_addr = save;
        ai->ai_addrlen = (socklen_t)afd->a_socklen;

        ai->ai_addr->sa_family = ai->ai_family = afd->a_af;
        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);
                if (sp == NULL)
                        return EAI_SERVICE;
                port = sp->s_port;
        }

        if (!matchonly)
                *getport(__DECONST(struct addrinfo*, ai)) = port;
        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;
}

/*
 * AI_ADDRCONFIG check: Build a mask containing a bit set for each address
 * family configured in the system.
 *
 */
static int
addrconfig(uint64_t *mask)
{
        struct ifaddrs *ifaddrs, *ifa;

        if (getifaddrs(&ifaddrs) == -1)
                return -1;

        *mask = 0;
        for (ifa = ifaddrs; ifa != NULL; ifa = ifa->ifa_next)
#ifndef __HAIKU__
                if (ifa->ifa_addr && (ifa->ifa_flags & IFF_UP)) {
#else
                if (ifa->ifa_addr && (ifa->ifa_flags & IFF_UP)
                                && !(ifa->ifa_flags & IFF_LOOPBACK)) {
                        assert(ifa->ifa_addr->sa_family < 64);
#endif
                        *mask |= (uint64_t)1 << ifa->ifa_addr->sa_family;
                }

        freeifaddrs(ifaddrs);
        return 0;
}

#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;
        }

        /* 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 const char AskedForGot[] =
        "gethostby*.getanswer: asked for \"%s\", got \"%s\"";

#define maybe_ok(res, nm, ok) (((res)->options & RES_NOCHECKNAME) != 0U || \
                               (ok)(nm) != 0)
static struct addrinfo *
getanswer(res_state res, const querybuf *answer, int anslen, const char *qname,
    int qtype, const struct addrinfo *pai)
{
        struct addrinfo sentinel, *cur;
        struct addrinfo ai, *aip;
        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 *);
        char hostbuf[8*1024];
        int port, pri, weight;
        struct srvinfo *srvlist, *srv, *csrv;

        _DIAGASSERT(answer != NULL);
        _DIAGASSERT(qname != NULL);
        _DIAGASSERT(pai != NULL);
        _DIAGASSERT(res != 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;
        case T_SRV:
                name_ok = gai_srvok;
                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) || !maybe_ok(res, bp, name_ok)) {
                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;
        srvlist = NULL;
        while (ancount-- > 0 && cp < eom && !had_error) {
                n = dn_expand(answer->buf, eom, cp, bp, (int)(ep - bp));
                if ((n < 0) || !maybe_ok(res, bp, name_ok)) {
                        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, (int)sizeof tbuf);
                        if ((n < 0) || !maybe_ok(res, tbuf, name_ok)) {
                                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) {
                                syslog(LOG_NOTICE|LOG_AUTH,
               "gethostby*.getanswer: asked for \"%s %s %s\", got type \"%s\"",
                                       qname, p_class(C_IN), p_type(qtype),
                                       p_type(type));
                        }
                        cp += n;
                        continue;               /* XXX - had_error++ ? */
                }
                switch (type) {
                case T_A:
                case T_AAAA:
                        if (strcasecmp(canonname, bp) != 0) {
                                syslog(LOG_NOTICE|LOG_AUTH,
                                       AskedForGot, canonname, bp);
                                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;
                case T_SRV:
                        /* Add to SRV list. Insertion sort on priority. */
                        pri = _getshort(cp);
                        cp += INT16SZ;
                        weight = _getshort(cp);
                        cp += INT16SZ;
                        port = _getshort(cp);
                        cp += INT16SZ;
                        n = dn_expand(answer->buf, eom, cp, tbuf,
                            (int)sizeof(tbuf));
                        if ((n < 0) || !maybe_ok(res, tbuf, res_hnok)) {
                                had_error++;
                                continue;
                        }
                        cp += n;
                        if (strlen(tbuf) + 1 >= MAXDNAME) {
                                had_error++;
                                continue;
                        }
                        srv = malloc(sizeof(*srv));
                        if (!srv) {
                                had_error++;
                                continue;
                        }
                        strlcpy(srv->name, tbuf, sizeof(srv->name));
                        srv->pri = pri;
                        srv->weight = weight;
                        srv->port = port;
                        /* Weight 0 is sorted before other weights. */
                        if (!srvlist
                            || srv->pri < srvlist->pri
                            || (srv->pri == srvlist->pri &&
                            (!srv->weight || srvlist->weight))) {
                                srv->next = srvlist;
                                srvlist = srv;
                        } else {
                                for (csrv = srvlist;
                                    csrv->next && csrv->next->pri <= srv->pri;
                                    csrv = csrv->next) {
                                        if (csrv->next->pri == srv->pri
                                            && (!srv->weight ||
                                            csrv->next->weight))
                                                break;
                                }
                                srv->next = csrv->next;
                                csrv->next = srv;
                        }
                        continue; /* Don't add to haveanswer yet. */
                default:
                        abort();
                }
                if (!had_error)
                        haveanswer++;
        }

        if (srvlist) {
                /*
                 * Check for explicit rejection.
                 */
                if (!srvlist->next && !srvlist->name[0]) {
                        free(srvlist);
                        h_errno = HOST_NOT_FOUND;
                        return NULL;
                }

                while (srvlist) {
                        struct res_target q, q2;

                        srv = srvlist;
                        srvlist = srvlist->next;

                        /*
                         * Since res_* doesn't give the additional
                         * section, we always look up.
                         */
                        memset(&q, 0, sizeof(q));
                        memset(&q2, 0, sizeof(q2));

                        q.name = srv->name;
                        q.qclass = C_IN;
                        q.qtype = T_AAAA;
                        q.next = &q2;
                        q2.name = srv->name;
                        q2.qclass = C_IN;
                        q2.qtype = T_A;

                        aip = _dns_query(&q, pai, res, 0);

                        if (aip != NULL) {
                                cur->ai_next = aip;
                                while (cur && cur->ai_next) {
                                        cur = cur->ai_next;
                                        *getport(cur) = htons(srv->port);
                                        haveanswer++;
                                }
                        }
                        free(srv);
                }
        }
        if (haveanswer) {
                if (!sentinel.ai_next->ai_canonname)
                       (void)get_canonname(pai, sentinel.ai_next,
                           canonname ? canonname : qname);
                h_errno = NETDB_SUCCESS;
                return sentinel.ai_next;
        }

        /* We could have walked a CNAME chain, */
        /* but the ultimate target may not have what we looked for */
        h_errno = ntohs(hp->ancount) > 0? NO_DATA : 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 < 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;
}

static struct addrinfo *
_dns_query(struct res_target *q, const struct addrinfo *pai,
    res_state res, int dosearch)
{
        struct res_target *q2 = q->next;
        querybuf *buf, *buf2;
        struct addrinfo sentinel, *cur, *ai;

#ifdef DNS_DEBUG
        struct res_target *iter;
        for (iter = q; iter; iter = iter->next)
                printf("Query type %d for %s\n", iter->qtype, iter->name);
#endif

        buf = malloc(sizeof(*buf));
        if (buf == NULL) {
                h_errno = NETDB_INTERNAL;
                return NULL;
        }
        buf2 = malloc(sizeof(*buf2));
        if (buf2 == NULL) {
                free(buf);
                h_errno = NETDB_INTERNAL;
                return NULL;
        }

        memset(&sentinel, 0, sizeof(sentinel));
        cur = &sentinel;

        q->answer = buf->buf;
        q->anslen = sizeof(buf->buf);
        if (q2) {
                q2->answer = buf2->buf;
                q2->anslen = sizeof(buf2->buf);
        }

        if (dosearch) {
                if (res_searchN(q->name, q, res) < 0)
                        goto out;
        } else {
                if (res_queryN(q->name, q, res) < 0)
                        goto out;
        }

        ai = getanswer(res, buf, q->n, q->name, q->qtype, pai);
        if (ai) {
                cur->ai_next = ai;
                while (cur && cur->ai_next)
                        cur = cur->ai_next;
        }
        if (q2) {
                if (!ai || pai->ai_family != AF_UNSPEC
                        || (pai->ai_flags & (AI_ALL | AI_V4MAPPED)) != AI_V4MAPPED) {
                        ai = getanswer(res, buf2, q2->n, q2->name, q2->qtype, pai);
                        if (ai)
                                cur->ai_next = ai;
                }
        }
        free(buf);
        free(buf2);
        return sentinel.ai_next;
out:
        free(buf);
        free(buf2);
        return NULL;
}

/*ARGSUSED*/
static struct addrinfo *
_dns_srv_lookup(const char *name, const char *servname,
    const struct addrinfo *pai)
{
        static const char * const srvprotos[] = { "tcp", "udp" };
        static const int srvnottype[] = { SOCK_DGRAM, SOCK_STREAM };
        static const int nsrvprotos = 2;
        struct addrinfo sentinel, *cur, *ai;
        struct servent *serv, sv;
        struct servent_data svd;
        struct res_target q;
        res_state res;
        char *tname;
        int i;

        res = __res_get_state();
        if (res == NULL)
                return NULL;

        memset(&svd, 0, sizeof(svd));
        memset(&sentinel, 0, sizeof(sentinel));
        cur = &sentinel;

        /*
         * Iterate over supported SRV protocols.
         * (currently UDP and TCP only)
         */
        for (i = 0; i < nsrvprotos; i++) {
                /*
                 * Check that the caller didn't specify a hint
                 * which precludes this protocol.
                 */
                if (pai->ai_socktype == srvnottype[i])
                        continue;
                /*
                 * If the caller specified a port,
                 * then lookup the database for the
                 * official service name.
                 */
                serv = getservbyname_r(servname, srvprotos[i], &sv, &svd);
                if (serv == NULL)
                        continue;

                /*
                 * Construct service DNS name.
                 */
                if (asprintf(&tname, "_%s._%s.%s", serv->s_name, serv->s_proto,
                    name) < 0)
                        continue;

                memset(&q, 0, sizeof(q));
                q.name = tname;
                q.qclass = C_IN;
                q.qtype = T_SRV;

                /*
                 * Do SRV query.
                 */
                ai = _dns_query(&q, pai, res, 1);
                if (ai) {
                        cur->ai_next = ai;
                        while (cur && cur->ai_next)
                                cur = cur->ai_next;
                }
                free(tname);
        }

        if (res->nsort)
                aisort(&sentinel, res);

        __res_put_state(res);

        return sentinel.ai_next;
}

/*ARGSUSED*/
static struct addrinfo *
_dns_host_lookup(const char *name, const struct addrinfo *pai)
{
        struct res_target q, q2;
        struct addrinfo sentinel, *ai;
        res_state res;

        res = __res_get_state();
        if (res == NULL)
                return NULL;

        memset(&q, 0, sizeof(q2));
        memset(&q2, 0, sizeof(q2));

        switch (pai->ai_family) {
        case AF_UNSPEC:
                /* prefer IPv6 */
                q.name = name;
                q.qclass = C_IN;
                q.qtype = T_AAAA;
                q.next = &q2;
                q2.name = name;
                q2.qclass = C_IN;
                q2.qtype = T_A;
                break;
        case AF_INET:
                q.name = name;
                q.qclass = C_IN;
                q.qtype = T_A;
                break;
        case AF_INET6:
                q.name = name;
                q.qclass = C_IN;
                q.qtype = T_AAAA;
                break;
        default:
                __res_put_state(res);
                h_errno = NETDB_INTERNAL;
                return NULL;
        }

        ai = _dns_query(&q, pai, res, 1);

        memset(&sentinel, 0, sizeof(sentinel));
        sentinel.ai_next = ai;

        if (ai != NULL && res->nsort)
                aisort(&sentinel, res);

        __res_put_state(res);

        return sentinel.ai_next;
}

/*ARGSUSED*/
static int
_dns_getaddrinfo(void *rv, void *cb_data, va_list ap)
{
        struct addrinfo ai0, *ai = NULL;
        const char *name, *servname;
        const struct addrinfo *pai;

        name = va_arg(ap, char *);
        pai = va_arg(ap, const struct addrinfo *);
        servname = va_arg(ap, char *);

        if (pai->ai_family == AF_INET6 && (pai->ai_flags & AI_V4MAPPED) == AI_V4MAPPED) {
                ai0 = *pai;
                ai0.ai_family = AF_UNSPEC;
                pai = &ai0;
        }

        /*
         * Try doing SRV lookup on service first.
         */
        if (servname
#ifdef AI_SRV
            && (pai->ai_flags & AI_SRV)
#endif
            && !(pai->ai_flags & AI_NUMERICSERV)
            && str2number(servname) == -1) {

#ifdef DNS_DEBUG
                printf("%s: try SRV lookup\n", __func__);
#endif
                ai = _dns_srv_lookup(name, servname, pai);
        }

        /*
         * Do lookup on name.
         */
        if (ai == NULL) {

#ifdef DNS_DEBUG
                printf("%s: try HOST lookup\n", __func__);
#endif
                ai = _dns_host_lookup(name, pai);

                if (ai == NULL) {
                        switch (h_errno) {
                        case HOST_NOT_FOUND:
                        case NO_DATA:   // XXX: Perhaps we could differentiate
                                        // So that we could return EAI_NODATA?
                                return NS_NOTFOUND;
                        case TRY_AGAIN:
                                return NS_TRYAGAIN;
                        default:
                                return NS_UNAVAIL;
                        }
                }
        }

        *((struct addrinfo **)rv) = ai;
        return NS_SUCCESS;
}

static void
_sethtent(FILE **hostf)
{

        if (!*hostf) {
                char buffer[256];
                find_directory(B_SYSTEM_SETTINGS_DIRECTORY, 0, false, buffer, sizeof(buffer));
                strlcat(buffer, "/network/hosts", sizeof(buffer));

                *hostf = fopen(buffer, "re");
        } 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;
        char hostbuf[8*1024];

        assert(name != NULL);
        assert(pai != NULL);

        if (!*hostf)
                _sethtent(hostf);
        if (!*hostf)
                return (NULL);
 again:
        if (!(p = fgets(hostbuf, (int)sizeof hostbuf, *hostf)))
                return NULL;
        if (*p == '#')
                goto again;
        if (!(cp = strpbrk(p, "#\n")))
                goto again;
        *cp = '\0';
        if (!(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;

        if (pai->ai_family == AF_INET6 && (pai->ai_flags & AI_V4MAPPED) == AI_V4MAPPED)
                hints.ai_flags |= AI_V4MAPPED;

        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;
}


static struct addrinfo*
_getht(FILE** hostf, const char* name, const struct addrinfo* pai, struct addrinfo* cur)
{
        struct addrinfo* p;

        while ((p = _gethtent(hostf, name, pai)) != NULL) {
                cur->ai_next = p;
                while (cur && cur->ai_next)
                        cur = cur->ai_next;
        }
        return cur;
}

/*ARGSUSED*/
static int
_files_getaddrinfo(void *rv, void *cb_data, va_list ap)
{
        const char *name;
        const struct addrinfo *pai;
        struct addrinfo sentinel, *cur;
#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);
        if (pai->ai_family == AF_INET6 && (pai->ai_flags & (AI_ALL | AI_V4MAPPED)) == AI_V4MAPPED) {
                struct addrinfo ai0 = *pai;

                ai0.ai_flags &= ~AI_V4MAPPED;
                cur = _getht(&hostf, name, &ai0, cur);
                if (sentinel.ai_next == NULL) {
                        _sethtent(&hostf);
                        ai0.ai_flags |= AI_V4MAPPED;
                        cur = _getht(&hostf, name, &ai0, cur);
                }
        } else {
                cur = _getht(&hostf, name, pai, cur);
        }
        _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;
        if (pai->ai_family == AF_INET6 && (pai->ai_flags & AI_V4MAPPED) == AI_V4MAPPED)
                hints.ai_flags |= AI_V4MAPPED;
        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;

        /* 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;
                        while (cur && cur->ai_next)
                                cur = cur->ai_next;
                }
                free(ypbuf);
        }

        if (ai != NULL) {
                struct sockaddr_in6* sin6;

                switch (ai->ai_family) {
                        case AF_INET:
                                goto done;
                        case AF_INET6:
                                sin6 = (struct sockaddr_in6*)ai->ai_addr;
                                if (IN6_IS_ADDR_V4MAPPED(&sin6->sin6_addr))
                                        goto done;
                                break;
                }
        }

        /* hosts.byname is only for IPv4 (Solaris8) */
        if (pai->ai_family == AF_UNSPEC || pai->ai_family == AF_INET
                || ((pai->ai_family == AF_INET6 && (pai->ai_flags & AI_V4MAPPED) == AI_V4MAPPED)
                        && (ai == NULL || (pai->ai_flags & AI_ALL) == AI_ALL))) {
                r = yp_match(ypdomain, "hosts.byname", name,
                        (int)strlen(name), &ypbuf, &ypbuflen);
                if (r == 0) {
                        struct addrinfo ai4;

                        ai4 = *pai;
                        if (pai->ai_family == AF_UNSPEC)
                                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);
        }

done:
        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 statp)
{
        u_char buf[MAXPACKET];
        HEADER *hp;
        int n;
        struct res_target *t;
        int rcode;
        u_char *rdata;
        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;
                u_int oflags;

                hp = (HEADER *)(void *)t->answer;
                oflags = statp->_flags;

again:
                hp->rcode = NOERROR;    /* default */

                /* make it easier... */
                class = t->qclass;
                type = t->qtype;
                answer = t->answer;
                anslen = t->anslen;
#ifdef DEBUG
                if (statp->options & RES_DEBUG)
                        printf(";; res_nquery(%s, %d, %d)\n", name, class, type);
#endif

                n = res_nmkquery(statp, QUERY, name, class, type, NULL, 0, NULL,
                    buf, (int)sizeof(buf));
#ifdef RES_USE_EDNS0
                if (n > 0 && (statp->_flags & RES_F_EDNS0ERR) == 0 &&
                    (statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0) {
                        n = res_nopt(statp, n, buf, (int)sizeof(buf), anslen);
                        rdata = &buf[n];
                        if (n > 0 && (statp->options & RES_NSID) != 0U) {
                                n = res_nopt_rdata(statp, n, buf,
                                    (int)sizeof(buf),
                                    rdata, NS_OPT_NSID, 0, NULL);
                        }
                }
#endif
                if (n <= 0) {
#ifdef DEBUG
                        if (statp->options & RES_DEBUG)
                                printf(";; res_nquery: mkquery failed\n");
#endif
                        h_errno = NO_RECOVERY;
                        return n;
                }
                n = res_nsend(statp, buf, n, answer, anslen);
                if (n < 0) {
#ifdef RES_USE_EDNS0
                        /* if the query choked with EDNS0, retry without EDNS0 */
                        if ((statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0U &&
                            ((oflags ^ statp->_flags) & RES_F_EDNS0ERR) != 0) {
                                statp->_flags |= RES_F_EDNS0ERR;
                                if (statp->options & RES_DEBUG)
                                        printf(";; res_nquery: retry without EDNS0\n");
                                goto again;
                        }
#endif
#if 0
#ifdef DEBUG
                        if (statp->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 (statp->options & RES_DEBUG)
                                printf(";; rcode = (%s), counts = an:%d ns:%d ar:%d\n",
                                       p_rcode(hp->rcode),
                                       ntohs(hp->ancount),
                                       ntohs(hp->nscount),
                                       ntohs(hp->arcount));
#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;
        char buf[MAXHOSTNAMELEN];
        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 = res_hostalias(res, name, buf, sizeof(buf))) != 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);
}

#ifdef TEST
int
main(int argc, char *argv[]) {
        struct addrinfo *ai, *sai;
        int i, e;
        char buf[1024];

        for (i = 1; i < argc; i++) {
                if ((e = getaddrinfo(argv[i], NULL, NULL, &sai)) != 0)
                        warnx("%s: %s", argv[i], gai_strerror(e));
                for (ai = sai; ai; ai = ai->ai_next) {
                        sockaddr_snprintf(buf, sizeof(buf), "%a", ai->ai_addr);
                        printf("flags=0x%x family=%d socktype=%d protocol=%d "
                            "addrlen=%zu addr=%s canonname=%s next=%p\n",
                            ai->ai_flags,
                            ai->ai_family,
                            ai->ai_socktype,
                            ai->ai_protocol,
                            (size_t)ai->ai_addrlen,
                            buf,
                            ai->ai_canonname,
                            ai->ai_next);
                }
                if (sai)
                        freeaddrinfo(sai);
        }
        return 0;
}
#endif