/*-
 * SPDX-License-Identifier: BSD-4-Clause
 *
 * Copyright (c) 1995
 *      Bill Paul <wpaul@ctr.columbia.edu>.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by Bill Paul.
 * 4. Neither the name of the author nor the names of any co-contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY Bill Paul 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 Bill Paul 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.
 */

#include <sys/cdefs.h>
#include <db.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <paths.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/param.h>
#include <rpcsvc/yp.h>
#include "yp_extern.h"

int ypdb_debug = 0;
enum ypstat yp_errno = YP_TRUE;

#define PERM_SECURE (S_IRUSR|S_IWUSR)
HASHINFO openinfo = {
        4096,           /* bsize */
        32,             /* ffactor */
        256,            /* nelem */
        2048 * 512,     /* cachesize */
        NULL,           /* hash */
        0,              /* lorder */
};

#ifdef DB_CACHE
#include <sys/queue.h>

#ifndef MAXDBS
#define MAXDBS 20
#endif

static int numdbs = 0;

struct dbent {
        DB *dbp;
        char *name;
        char *key;
        int size;
        int flags;
};

static TAILQ_HEAD(circlehead, circleq_entry) qhead;

struct circleq_entry {
        struct dbent *dbptr;
        TAILQ_ENTRY(circleq_entry) links;
};

/*
 * Initialize the circular queue.
 */
void
yp_init_dbs(void)
{
        TAILQ_INIT(&qhead);
}

/*
 * Dynamically allocate an entry for the circular queue.
 * Return a NULL pointer on failure.
 */
static struct circleq_entry *
yp_malloc_qent(void)
{
        register struct circleq_entry *q;

        q = malloc(sizeof(struct circleq_entry));
        if (q == NULL) {
                yp_error("failed to malloc() circleq entry");
                return(NULL);
        }
        bzero((char *)q, sizeof(struct circleq_entry));
        q->dbptr = malloc(sizeof(struct dbent));
        if (q->dbptr == NULL) {
                yp_error("failed to malloc() circleq entry");
                free(q);
                return(NULL);
        }
        bzero((char *)q->dbptr, sizeof(struct dbent));

        return(q);
}

/*
 * Free a previously allocated circular queue
 * entry.
 */
static void
yp_free_qent(struct circleq_entry *q)
{
        /*
         * First, close the database. In theory, this is also
         * supposed to free the resources allocated by the DB
         * package, including the memory pointed to by q->dbptr->key.
         * This means we don't have to free q->dbptr->key here.
         */
        if (q->dbptr->dbp) {
                (void)(q->dbptr->dbp->close)(q->dbptr->dbp);
                q->dbptr->dbp = NULL;
        }
        /*
         * Then free the database name, which was strdup()'ed.
         */
        free(q->dbptr->name);

        /*
         * Free the rest of the dbent struct.
         */
        free(q->dbptr);
        q->dbptr = NULL;

        /*
         * Free the circleq struct.
         */
        free(q);
        q = NULL;
}

/*
 * Zorch a single entry in the dbent queue and release
 * all its resources. (This always removes the last entry
 * in the queue.)
 */
static void
yp_flush(void)
{
        register struct circleq_entry *qptr;

        qptr = TAILQ_LAST(&qhead, circlehead);
        TAILQ_REMOVE(&qhead, qptr, links);
        yp_free_qent(qptr);
        numdbs--;
}

/*
 * Close all databases, erase all database names and empty the queue.
 */
void
yp_flush_all(void)
{
        register struct circleq_entry *qptr;

        while (!TAILQ_EMPTY(&qhead)) {
                qptr = TAILQ_FIRST(&qhead); /* save this */
                TAILQ_REMOVE(&qhead, qptr, links);
                yp_free_qent(qptr);
        }
        numdbs = 0;

}

static char *inter_string = "YP_INTERDOMAIN";
static char *secure_string = "YP_SECURE";
static int inter_sz = sizeof("YP_INTERDOMAIN") - 1;
static int secure_sz = sizeof("YP_SECURE") - 1;

static int
yp_setflags(DB *dbp)
{
        DBT key = { NULL, 0 }, data = { NULL, 0 };
        int flags = 0;

        key.data = inter_string;
        key.size = inter_sz;

        if (!(dbp->get)(dbp, &key, &data, 0))
                flags |= YP_INTERDOMAIN;

        key.data = secure_string;
        key.size = secure_sz;

        if (!(dbp->get)(dbp, &key, &data, 0))
                flags |= YP_SECURE;

        return(flags);
}

int
yp_testflag(char *map, char *domain, int flag)
{
        char buf[MAXPATHLEN + 2];
        register struct circleq_entry *qptr;

        if (map == NULL || domain == NULL)
                return(0);

        strcpy(buf, domain);
        strcat(buf, "/");
        strcat(buf, map);

        TAILQ_FOREACH(qptr, &qhead, links) {
                if (!strcmp(qptr->dbptr->name, buf)) {
                        if (qptr->dbptr->flags & flag)
                                return(1);
                        else
                                return(0);
                }
        }

        if (yp_open_db_cache(domain, map, NULL, 0) == NULL)
                return(0);

        if (TAILQ_FIRST(&qhead)->dbptr->flags & flag)
                return(1);

        return(0);
}

/*
 * Add a DB handle and database name to the cache. We only maintain
 * fixed number of entries in the cache, so if we're asked to store
 * a new entry when all our slots are already filled, we have to kick
 * out the entry in the last slot to make room.
 */
static int
yp_cache_db(DB *dbp, char *name, int size)
{
        register struct circleq_entry *qptr;

        if (numdbs == MAXDBS) {
                if (ypdb_debug)
                        yp_error("queue overflow -- releasing last slot");
                yp_flush();
        }

        /*
         * Allocate a new queue entry.
         */

        if ((qptr = yp_malloc_qent()) == NULL) {
                yp_error("failed to allocate a new cache entry");
                return(1);
        }

        qptr->dbptr->dbp = dbp;
        qptr->dbptr->name = strdup(name);
        qptr->dbptr->size = size;
        qptr->dbptr->key = NULL;

        qptr->dbptr->flags = yp_setflags(dbp);

        TAILQ_INSERT_HEAD(&qhead, qptr, links);
        numdbs++;

        return(0);
}

/*
 * Search the list for a database matching 'name.' If we find it,
 * move it to the head of the list and return its DB handle. If
 * not, just fail: yp_open_db_cache() will subsequently try to open
 * the database itself and call yp_cache_db() to add it to the
 * list.
 *
 * The search works like this:
 *
 * - The caller specifies the name of a database to locate. We try to
 *   find an entry in our queue with a matching name.
 *
 * - If the caller doesn't specify a key or size, we assume that the
 *   first entry that we encounter with a matching name is returned.
 *   This will result in matches regardless of the key/size values
 *   stored in the queue entry.
 *
 * - If the caller also specifies a key and length, we check to see
 *   if the key and length saved in the queue entry also matches.
 *   This lets us return a DB handle that's already positioned at the
 *   correct location within a database.
 *
 * - Once we have a match, it gets migrated to the top of the queue
 *   so that it will be easier to find if another request for
 *   the same database comes in later.
 */
static DB *
yp_find_db(const char *name, const char *key, int size)
{
        register struct circleq_entry *qptr;

        TAILQ_FOREACH(qptr, &qhead, links) {
                if (!strcmp(qptr->dbptr->name, name)) {
                        if (size) {
                                if (size != qptr->dbptr->size ||
                                   strncmp(qptr->dbptr->key, key, size))
                                        continue;
                        } else {
                                if (qptr->dbptr->size)
                                        continue;
                        }
                        if (qptr != TAILQ_FIRST(&qhead)) {
                                TAILQ_REMOVE(&qhead, qptr, links);
                                TAILQ_INSERT_HEAD(&qhead, qptr, links);
                        }
                        return(qptr->dbptr->dbp);
                }
        }

        return(NULL);
}

/*
 * Open a DB database and cache the handle for later use. We first
 * check the cache to see if the required database is already open.
 * If so, we fetch the handle from the cache. If not, we try to open
 * the database and save the handle in the cache for later use.
 */
DB *
yp_open_db_cache(const char *domain, const char *map, const char *key,
    const int size)
{
        DB *dbp = NULL;
        char buf[MAXPATHLEN + 2];
/*
        snprintf(buf, sizeof(buf), "%s/%s", domain, map);
*/
        yp_errno = YP_TRUE;

        strcpy(buf, domain);
        strcat(buf, "/");
        strcat(buf, map);

        if ((dbp = yp_find_db(buf, key, size)) != NULL) {
                return(dbp);
        } else {
                if ((dbp = yp_open_db(domain, map)) != NULL) {
                        if (yp_cache_db(dbp, buf, size)) {
                                (void)(dbp->close)(dbp);
                                yp_errno = YP_YPERR;
                                return(NULL);
                        }
                }
        }

        return (dbp);
}
#endif

/*
 * Open a DB database.
 */
DB *
yp_open_db(const char *domain, const char *map)
{
        DB *dbp = NULL;
        char buf[MAXPATHLEN + 2];

        yp_errno = YP_TRUE;

        if (map[0] == '.' || strchr(map, '/')) {
                yp_errno = YP_BADARGS;
                return (NULL);
        }

#ifdef DB_CACHE
        if (yp_validdomain(domain)) {
                yp_errno = YP_NODOM;
                return(NULL);
        }
#endif
        snprintf(buf, sizeof(buf), "%s/%s/%s", yp_dir, domain, map);

#ifdef DB_CACHE
again:
#endif
        dbp = dbopen(buf, O_RDONLY, PERM_SECURE, DB_HASH, NULL);

        if (dbp == NULL) {
                switch (errno) {
#ifdef DB_CACHE
                case ENFILE:
                        /*
                         * We ran out of file descriptors. Nuke an
                         * open one and try again.
                         */
                        yp_error("ran out of file descriptors");
                        yp_flush();
                        goto again;
                        break;
#endif
                case ENOENT:
                        yp_errno = YP_NOMAP;
                        break;
                case EFTYPE:
                        yp_errno = YP_BADDB;
                        break;
                default:
                        yp_errno = YP_YPERR;
                        break;
                }
        }

        return (dbp);
}

/*
 * Database access routines.
 *
 * - yp_get_record(): retrieve an arbitrary key/data pair given one key
 *                 to match against.
 *
 * - yp_first_record(): retrieve first key/data base in a database.
 *
 * - yp_next_record(): retrieve key/data pair that sequentially follows
 *                   the supplied key value in the database.
 */

#ifdef DB_CACHE
int
yp_get_record(DB *dbp, const DBT *key, DBT *data, int allow)
#else
int
yp_get_record(const char *domain, const char *map,
    const DBT *key, DBT *data, int allow)
#endif
{
#ifndef DB_CACHE
        DB *dbp;
#endif
        int rval = 0;
#ifndef DB_CACHE
        static unsigned char buf[YPMAXRECORD];
#endif

        if (ypdb_debug)
                yp_error("looking up key [%.*s]",
                    (int)key->size, (char *)key->data);

        /*
         * Avoid passing back magic "YP_*" entries unless
         * the caller specifically requested them by setting
         * the 'allow' flag.
         */
        if (!allow && !strncmp(key->data, "YP_", 3))
                return(YP_NOKEY);

#ifndef DB_CACHE
        if ((dbp = yp_open_db(domain, map)) == NULL) {
                return(yp_errno);
        }
#endif

        if ((rval = (dbp->get)(dbp, key, data, 0)) != 0) {
#ifdef DB_CACHE
                TAILQ_FIRST(&qhead)->dbptr->size = 0;
#else
                (void)(dbp->close)(dbp);
#endif
                if (rval == 1)
                        return(YP_NOKEY);
                else
                        return(YP_BADDB);
        }

        if (ypdb_debug)
                yp_error("result of lookup: key: [%.*s] data: [%.*s]",
                    (int)key->size, (char *)key->data,
                    (int)data->size, (char *)data->data);

#ifdef DB_CACHE
        if (TAILQ_FIRST(&qhead)->dbptr->size) {
                TAILQ_FIRST(&qhead)->dbptr->key = "";
                TAILQ_FIRST(&qhead)->dbptr->size = 0;
        }
#else
        bcopy(data->data, &buf, data->size);
        data->data = &buf;
        (void)(dbp->close)(dbp);
#endif

        return(YP_TRUE);
}

int
yp_first_record(const DB *dbp, DBT *key, DBT *data, int allow)
{
        int rval;
#ifndef DB_CACHE
        static unsigned char buf[YPMAXRECORD];
#endif

        if (ypdb_debug)
                yp_error("retrieving first key in map");

        if ((rval = (dbp->seq)(dbp,key,data,R_FIRST)) != 0) {
#ifdef DB_CACHE
                TAILQ_FIRST(&qhead)->dbptr->size = 0;
#endif
                if (rval == 1)
                        return(YP_NOKEY);
                else
                        return(YP_BADDB);
        }

        /* Avoid passing back magic "YP_*" records. */
        while (!strncmp(key->data, "YP_", 3) && !allow) {
                if ((rval = (dbp->seq)(dbp,key,data,R_NEXT)) != 0) {
#ifdef DB_CACHE
                        TAILQ_FIRST(&qhead)->dbptr->size = 0;
#endif
                        if (rval == 1)
                                return(YP_NOKEY);
                        else
                                return(YP_BADDB);
                }
        }

        if (ypdb_debug)
                yp_error("result of lookup: key: [%.*s] data: [%.*s]",
                    (int)key->size, (char *)key->data,
                    (int)data->size, (char *)data->data);

#ifdef DB_CACHE
        if (TAILQ_FIRST(&qhead)->dbptr->size) {
                TAILQ_FIRST(&qhead)->dbptr->key = key->data;
                TAILQ_FIRST(&qhead)->dbptr->size = key->size;
        }
#else
        bcopy(data->data, &buf, data->size);
        data->data = &buf;
#endif

        return(YP_TRUE);
}

int
yp_next_record(const DB *dbp, DBT *key, DBT *data, int all, int allow)
{
        static DBT lkey = { NULL, 0 };
        static DBT ldata = { NULL, 0 };
        int rval;
#ifndef DB_CACHE
        static unsigned char keybuf[YPMAXRECORD];
        static unsigned char datbuf[YPMAXRECORD];
#endif

        if (key == NULL || !key->size || key->data == NULL) {
                rval = yp_first_record(dbp,key,data,allow);
                if (rval == YP_NOKEY)
                        return(YP_NOMORE);
                else {
#ifdef DB_CACHE
                        TAILQ_FIRST(&qhead)->dbptr->key = key->data;
                        TAILQ_FIRST(&qhead)->dbptr->size = key->size;
#endif
                        return(rval);
                }
        }

        if (ypdb_debug)
                yp_error("retrieving next key, previous was: [%.*s]",
                    (int)key->size, (char *)key->data);

        if (!all) {
#ifdef DB_CACHE
                if (TAILQ_FIRST(&qhead)->dbptr->key == NULL) {
#endif
                        (dbp->seq)(dbp,&lkey,&ldata,R_FIRST);
                        while (key->size != lkey.size ||
                            strncmp(key->data, lkey.data,
                            (int)key->size))
                                if ((dbp->seq)(dbp,&lkey,&ldata,R_NEXT)) {
#ifdef DB_CACHE
                                        TAILQ_FIRST(&qhead)->dbptr->size = 0;
#endif
                                        return(YP_NOKEY);
                                }

#ifdef DB_CACHE
                }
#endif
        }

        if ((dbp->seq)(dbp,key,data,R_NEXT)) {
#ifdef DB_CACHE
                TAILQ_FIRST(&qhead)->dbptr->size = 0;
#endif
                return(YP_NOMORE);
        }

        /* Avoid passing back magic "YP_*" records. */
        while (!strncmp(key->data, "YP_", 3) && !allow)
                if ((dbp->seq)(dbp,key,data,R_NEXT)) {
#ifdef DB_CACHE
                TAILQ_FIRST(&qhead)->dbptr->size = 0;
#endif
                        return(YP_NOMORE);
                }

        if (ypdb_debug)
                yp_error("result of lookup: key: [%.*s] data: [%.*s]",
                    (int)key->size, (char *)key->data,
                    (int)data->size, (char *)data->data);

#ifdef DB_CACHE
        if (TAILQ_FIRST(&qhead)->dbptr->size) {
                TAILQ_FIRST(&qhead)->dbptr->key = key->data;
                TAILQ_FIRST(&qhead)->dbptr->size = key->size;
        }
#else
        bcopy(key->data, &keybuf, key->size);
        lkey.data = &keybuf;
        lkey.size = key->size;
        bcopy(data->data, &datbuf, data->size);
        data->data = &datbuf;
#endif

        return(YP_TRUE);
}

#ifdef DB_CACHE
/*
 * Database glue functions.
 */

static DB *yp_currmap_db = NULL;
static int yp_allow_db = 0;

ypstat
yp_select_map(char *map, char *domain, keydat *key, int allow)
{
        if (key == NULL)
                yp_currmap_db = yp_open_db_cache(domain, map, NULL, 0);
        else
                yp_currmap_db = yp_open_db_cache(domain, map,
                                                 key->keydat_val,
                                                 key->keydat_len);

        yp_allow_db = allow;
        return(yp_errno);
}

ypstat
yp_getbykey(keydat *key, valdat *val)
{
        DBT db_key = { NULL, 0 }, db_val = { NULL, 0 };
        ypstat rval;

        db_key.data = key->keydat_val;
        db_key.size = key->keydat_len;

        rval = yp_get_record(yp_currmap_db,
                                &db_key, &db_val, yp_allow_db);

        if (rval == YP_TRUE) {
                val->valdat_val = db_val.data;
                val->valdat_len = db_val.size;
        }

        return(rval);
}

ypstat
yp_firstbykey(keydat *key, valdat *val)
{
        DBT db_key = { NULL, 0 }, db_val = { NULL, 0 };
        ypstat rval;

        rval = yp_first_record(yp_currmap_db, &db_key, &db_val, yp_allow_db);

        if (rval == YP_TRUE) {
                key->keydat_val = db_key.data;
                key->keydat_len = db_key.size;
                val->valdat_val = db_val.data;
                val->valdat_len = db_val.size;
        }

        return(rval);
}

ypstat
yp_nextbykey(keydat *key, valdat *val)
{
        DBT db_key = { NULL, 0 }, db_val = { NULL, 0 };
        ypstat rval;

        db_key.data = key->keydat_val;
        db_key.size = key->keydat_len;

        rval = yp_next_record(yp_currmap_db, &db_key, &db_val, 0, yp_allow_db);

        if (rval == YP_TRUE) {
                key->keydat_val = db_key.data;
                key->keydat_len = db_key.size;
                val->valdat_val = db_val.data;
                val->valdat_len = db_val.size;
        }

        return(rval);
}
#endif