/*
 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
 * Copyright (c) 1996,1999 by Internet Software Consortium.
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
 * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

/* Imports */

#include "port_before.h"

#include <sys/types.h>

#include <netinet/in.h>
#include <arpa/nameser.h>

#include <errno.h>
#include <stdlib.h>
#include <netdb.h>
#include <resolv.h>
#include <stdio.h>
#include <string.h>

#include <isc/memcluster.h>
#include <irs.h>

#include "port_after.h"

#include "irs_p.h"
#include "gen_p.h"

/* Definitions */

struct pvt {
        struct irs_rule *       rules;
        struct irs_rule *       rule;
        struct irs_ho *         ho;
        struct __res_state *    res;
        void                    (*free_res)(void *);
};

/* Forwards */

static void             ho_close(struct irs_ho *this);
static struct hostent * ho_byname(struct irs_ho *this, const char *name);
static struct hostent * ho_byname2(struct irs_ho *this, const char *name,
                                   int af);
static struct hostent * ho_byaddr(struct irs_ho *this, const void *addr,
                                  int len, int af);
static struct hostent * ho_next(struct irs_ho *this);
static void             ho_rewind(struct irs_ho *this);
static void             ho_minimize(struct irs_ho *this);
static struct __res_state * ho_res_get(struct irs_ho *this);
static void             ho_res_set(struct irs_ho *this,
                                   struct __res_state *res,
                                   void (*free_res)(void *));
static struct addrinfo * ho_addrinfo(struct irs_ho *this, const char *name,
                                     const struct addrinfo *pai);

static int              init(struct irs_ho *this);

/* Exports */

struct irs_ho *
irs_gen_ho(struct irs_acc *this) {
        struct gen_p *accpvt = (struct gen_p *)this->private;
        struct irs_ho *ho;
        struct pvt *pvt;

        if (!(pvt = memget(sizeof *pvt))) {
                errno = ENOMEM;
                return (NULL);
        }
        memset(pvt, 0, sizeof *pvt);
        if (!(ho = memget(sizeof *ho))) {
                memput(pvt, sizeof *pvt);
                errno = ENOMEM;
                return (NULL);
        }
        memset(ho, 0x5e, sizeof *ho);
        pvt->rules = accpvt->map_rules[irs_ho];
        pvt->rule = pvt->rules;
        ho->private = pvt;
        ho->close = ho_close;
        ho->byname = ho_byname;
        ho->byname2 = ho_byname2;
        ho->byaddr = ho_byaddr;
        ho->next = ho_next;
        ho->rewind = ho_rewind;
        ho->minimize = ho_minimize;
        ho->res_get = ho_res_get;
        ho->res_set = ho_res_set;
        ho->addrinfo = ho_addrinfo;
        return (ho);
}

/* Methods. */

static void
ho_close(struct irs_ho *this) {
        struct pvt *pvt = (struct pvt *)this->private;

        ho_minimize(this);
        if (pvt->res && pvt->free_res)
                (*pvt->free_res)(pvt->res);
        memput(pvt, sizeof *pvt);
        memput(this, sizeof *this);
}

static struct hostent *
ho_byname(struct irs_ho *this, const char *name) {
        struct pvt *pvt = (struct pvt *)this->private;
        struct irs_rule *rule;
        struct hostent *rval;
        struct irs_ho *ho;
        int therrno = NETDB_INTERNAL;
        int softerror = 0;

        if (init(this) == -1)
                return (NULL);

        for (rule = pvt->rules; rule; rule = rule->next) {
                ho = rule->inst->ho;
                RES_SET_H_ERRNO(pvt->res, NETDB_INTERNAL);
                errno = 0;
                rval = (*ho->byname)(ho, name);
                if (rval != NULL)
                        return (rval);
                if (softerror == 0 &&
                    pvt->res->res_h_errno != HOST_NOT_FOUND &&
                    pvt->res->res_h_errno != NETDB_INTERNAL) {
                        softerror = 1;
                        therrno = pvt->res->res_h_errno;
                }
                if (rule->flags & IRS_CONTINUE)
                        continue;
                /*
                 * The value TRY_AGAIN can mean that the service
                 * is not available, or just that this particular name
                 * cannot be resolved now.  We use the errno ECONNREFUSED
                 * to distinguish.  If a lookup sets that errno when
                 * H_ERRNO is TRY_AGAIN, we continue to try other lookup
                 * functions, otherwise we return the TRY_AGAIN error.
                 */
                if (pvt->res->res_h_errno != TRY_AGAIN || errno != ECONNREFUSED)
                        break;
        }
        if (softerror != 0 && pvt->res->res_h_errno == HOST_NOT_FOUND)
                RES_SET_H_ERRNO(pvt->res, therrno);
        return (NULL);
}

static struct hostent *
ho_byname2(struct irs_ho *this, const char *name, int af) {
        struct pvt *pvt = (struct pvt *)this->private;
        struct irs_rule *rule;
        struct hostent *rval;
        struct irs_ho *ho;
        int therrno = NETDB_INTERNAL;
        int softerror = 0;

        if (init(this) == -1)
                return (NULL);

        for (rule = pvt->rules; rule; rule = rule->next) {
                ho = rule->inst->ho;
                RES_SET_H_ERRNO(pvt->res, NETDB_INTERNAL);
                errno = 0;
                rval = (*ho->byname2)(ho, name, af);
                if (rval != NULL)
                        return (rval);
                if (softerror == 0 &&
                    pvt->res->res_h_errno != HOST_NOT_FOUND &&
                    pvt->res->res_h_errno != NETDB_INTERNAL) {
                        softerror = 1;
                        therrno = pvt->res->res_h_errno;
                }
                if (rule->flags & IRS_CONTINUE)
                        continue;
                /*
                 * See the comments in ho_byname() explaining
                 * the interpretation of TRY_AGAIN and ECONNREFUSED.
                 */
                if (pvt->res->res_h_errno != TRY_AGAIN || errno != ECONNREFUSED)
                        break;
        }
        if (softerror != 0 && pvt->res->res_h_errno == HOST_NOT_FOUND)
                RES_SET_H_ERRNO(pvt->res, therrno);
        return (NULL);
}

static struct hostent *
ho_byaddr(struct irs_ho *this, const void *addr, int len, int af) {
        struct pvt *pvt = (struct pvt *)this->private;
        struct irs_rule *rule;
        struct hostent *rval;
        struct irs_ho *ho;
        int therrno = NETDB_INTERNAL;
        int softerror = 0;


        if (init(this) == -1)
                return (NULL);

        for (rule = pvt->rules; rule; rule = rule->next) {
                ho = rule->inst->ho;
                RES_SET_H_ERRNO(pvt->res, NETDB_INTERNAL);
                errno = 0;
                rval = (*ho->byaddr)(ho, addr, len, af);
                if (rval != NULL)
                        return (rval);
                if (softerror == 0 &&
                    pvt->res->res_h_errno != HOST_NOT_FOUND &&
                    pvt->res->res_h_errno != NETDB_INTERNAL) {
                        softerror = 1;
                        therrno = pvt->res->res_h_errno;
                }

                if (rule->flags & IRS_CONTINUE)
                        continue;
                /*
                 * See the comments in ho_byname() explaining
                 * the interpretation of TRY_AGAIN and ECONNREFUSED.
                 */
                if (pvt->res->res_h_errno != TRY_AGAIN || errno != ECONNREFUSED)
                        break;
        }
        if (softerror != 0 && pvt->res->res_h_errno == HOST_NOT_FOUND)
                RES_SET_H_ERRNO(pvt->res, therrno);
        return (NULL);
}

static struct hostent *
ho_next(struct irs_ho *this) {
        struct pvt *pvt = (struct pvt *)this->private;
        struct hostent *rval;
        struct irs_ho *ho;

        while (pvt->rule) {
                ho = pvt->rule->inst->ho;
                rval = (*ho->next)(ho);
                if (rval)
                        return (rval);
                if (!(pvt->rule->flags & IRS_CONTINUE))
                        break;
                pvt->rule = pvt->rule->next;
                if (pvt->rule) {
                        ho = pvt->rule->inst->ho;
                        (*ho->rewind)(ho);
                }
        }
        return (NULL);
}

static void
ho_rewind(struct irs_ho *this) {
        struct pvt *pvt = (struct pvt *)this->private;
        struct irs_ho *ho;

        pvt->rule = pvt->rules;
        if (pvt->rule) {
                ho = pvt->rule->inst->ho;
                (*ho->rewind)(ho);
        }
}

static void
ho_minimize(struct irs_ho *this) {
        struct pvt *pvt = (struct pvt *)this->private;
        struct irs_rule *rule;

        if (pvt->res)
                res_nclose(pvt->res);
        for (rule = pvt->rules; rule != NULL; rule = rule->next) {
                struct irs_ho *ho = rule->inst->ho;

                (*ho->minimize)(ho);
        }
}

static struct __res_state *
ho_res_get(struct irs_ho *this) {
        struct pvt *pvt = (struct pvt *)this->private;

        if (!pvt->res) {
                struct __res_state *res;
                res = (struct __res_state *)malloc(sizeof *res);
                if (!res) {
                        errno = ENOMEM;
                        return (NULL);
                }
                memset(res, 0, sizeof *res);
                ho_res_set(this, res, free);
        }

        return (pvt->res);
}

static void
ho_res_set(struct irs_ho *this, struct __res_state *res,
                void (*free_res)(void *)) {
        struct pvt *pvt = (struct pvt *)this->private;
        struct irs_rule *rule;

        if (pvt->res && pvt->free_res) {
                res_nclose(pvt->res);
                (*pvt->free_res)(pvt->res);
        }

        pvt->res = res;
        pvt->free_res = free_res;

        for (rule = pvt->rules; rule != NULL; rule = rule->next) {
                struct irs_ho *ho = rule->inst->ho;

                (*ho->res_set)(ho, pvt->res, NULL);
        }
}

static struct addrinfo *
ho_addrinfo(struct irs_ho *this, const char *name, const struct addrinfo *pai)
{
        struct pvt *pvt = (struct pvt *)this->private;
        struct irs_rule *rule;
        struct addrinfo *rval = NULL;
        struct irs_ho *ho;
        int therrno = NETDB_INTERNAL;
        int softerror = 0;

        if (init(this) == -1)
                return (NULL);

        for (rule = pvt->rules; rule; rule = rule->next) {
                ho = rule->inst->ho;
                RES_SET_H_ERRNO(pvt->res, NETDB_INTERNAL);
                errno = 0;
                if (ho->addrinfo == NULL) /*%< for safety */
                        continue;
                rval = (*ho->addrinfo)(ho, name, pai);
                if (rval != NULL)
                        return (rval);
                if (softerror == 0 &&
                    pvt->res->res_h_errno != HOST_NOT_FOUND &&
                    pvt->res->res_h_errno != NETDB_INTERNAL) {
                        softerror = 1;
                        therrno = pvt->res->res_h_errno;
                }
                if (rule->flags & IRS_CONTINUE)
                        continue;
                /*
                 * See the comments in ho_byname() explaining
                 * the interpretation of TRY_AGAIN and ECONNREFUSED.
                 */
                if (pvt->res->res_h_errno != TRY_AGAIN ||
                    errno != ECONNREFUSED)
                        break;
        }
        if (softerror != 0 && pvt->res->res_h_errno == HOST_NOT_FOUND)
                RES_SET_H_ERRNO(pvt->res, therrno);
        return (NULL);
}

static int
init(struct irs_ho *this) {
        struct pvt *pvt = (struct pvt *)this->private;

        if (!pvt->res && !ho_res_get(this))
                return (-1);

        if (((pvt->res->options & RES_INIT) == 0U) &&
            (res_ninit(pvt->res) == -1))
                return (-1);

        return (0);
}

/*! \file */