/*      $NetBSD: pwcache.c,v 1.35 2024/05/12 10:58:58 rillig Exp $      */

/*-
 * Copyright (c) 1992 Keith Muller.
 * Copyright (c) 1992, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Keith Muller of the University of California, San Diego.
 *
 * 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 University 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 REGENTS 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 REGENTS 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.
 */

/*-
 * Copyright (c) 2002 The NetBSD Foundation, Inc.
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
 */

#if HAVE_NBTOOL_CONFIG_H
#include "nbtool_config.h"
/*
 * XXX Undefine the renames of these functions so that we don't
 * XXX rename the versions found in the host's <pwd.h> by mistake!
 */
#undef group_from_gid
#undef user_from_uid
#endif

#include <sys/cdefs.h>
#if defined(LIBC_SCCS) && !defined(lint)
#if 0
static char sccsid[] = "@(#)cache.c     8.1 (Berkeley) 5/31/93";
#else
__RCSID("$NetBSD: pwcache.c,v 1.35 2024/05/12 10:58:58 rillig Exp $");
#endif
#endif /* LIBC_SCCS and not lint */

#include "namespace.h"

#include <sys/types.h>
#include <sys/param.h>

#include <assert.h>
#include <grp.h>
#include <pwd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#if HAVE_NBTOOL_CONFIG_H
/* XXX Now, re-apply the renaming that we undid above. */
#define group_from_gid  __nbcompat_group_from_gid
#define user_from_uid   __nbcompat_user_from_uid
#endif

#ifdef __weak_alias
__weak_alias(user_from_uid,_user_from_uid)
__weak_alias(group_from_gid,_group_from_gid)
__weak_alias(pwcache_groupdb,_pwcache_groupdb)
#endif

#if !HAVE_PWCACHE_USERDB || HAVE_NBTOOL_CONFIG_H
#include "pwcache.h"

/*
 * routines that control user, group, uid and gid caches (for the archive
 * member print routine).
 * IMPORTANT:
 * these routines cache BOTH hits and misses, a major performance improvement
 */

/*
 * function pointers to various name lookup routines.
 * these may be changed as necessary.
 */
static  int             (*_pwcache_setgroupent)(int)            = setgroupent;
static  void            (*_pwcache_endgrent)(void)              = endgrent;
static  struct group *  (*_pwcache_getgrnam)(const char *)      = getgrnam;
static  struct group *  (*_pwcache_getgrgid)(gid_t)             = getgrgid;
static  int             (*_pwcache_setpassent)(int)             = setpassent;
static  void            (*_pwcache_endpwent)(void)              = endpwent;
static  struct passwd * (*_pwcache_getpwnam)(const char *)      = getpwnam;
static  struct passwd * (*_pwcache_getpwuid)(uid_t)             = getpwuid;

/*
 * internal state
 */
static  int     pwopn;          /* is password file open */
static  int     gropn;          /* is group file open */
static  UIDC    **uidtb;        /* uid to name cache */
static  GIDC    **gidtb;        /* gid to name cache */
static  UIDC    **usrtb;        /* user name to uid cache */
static  GIDC    **grptb;        /* group name to gid cache */

static  int     uidtb_fail;     /* uidtb_start() failed ? */
static  int     gidtb_fail;     /* gidtb_start() failed ? */
static  int     usrtb_fail;     /* usrtb_start() failed ? */
static  int     grptb_fail;     /* grptb_start() failed ? */


static  u_int   st_hash(const char *, size_t, int);
static  int     uidtb_start(void);
static  int     gidtb_start(void);
static  int     usrtb_start(void);
static  int     grptb_start(void);


static u_int
st_hash(const char *name, size_t len, int tabsz)
{
        u_int key = 0;

        _DIAGASSERT(name != NULL);

        while (len--) {
                key += *name++;
                key = (key << 8) | (key >> 24);
        }

        return (key % tabsz);
}

/*
 * uidtb_start
 *      creates an empty uidtb
 * Return:
 *      0 if ok, -1 otherwise
 */
static int
uidtb_start(void)
{

        if (uidtb != NULL)
                return (0);
        if (uidtb_fail)
                return (-1);
        if ((uidtb = (UIDC **)calloc(UID_SZ, sizeof(UIDC *))) == NULL) {
                ++uidtb_fail;
                return (-1);
        }
        return (0);
}

/*
 * gidtb_start
 *      creates an empty gidtb
 * Return:
 *      0 if ok, -1 otherwise
 */
static int
gidtb_start(void)
{

        if (gidtb != NULL)
                return (0);
        if (gidtb_fail)
                return (-1);
        if ((gidtb = (GIDC **)calloc(GID_SZ, sizeof(GIDC *))) == NULL) {
                ++gidtb_fail;
                return (-1);
        }
        return (0);
}

/*
 * usrtb_start
 *      creates an empty usrtb
 * Return:
 *      0 if ok, -1 otherwise
 */
static int
usrtb_start(void)
{

        if (usrtb != NULL)
                return (0);
        if (usrtb_fail)
                return (-1);
        if ((usrtb = (UIDC **)calloc(UNM_SZ, sizeof(UIDC *))) == NULL) {
                ++usrtb_fail;
                return (-1);
        }
        return (0);
}

/*
 * grptb_start
 *      creates an empty grptb
 * Return:
 *      0 if ok, -1 otherwise
 */
static int
grptb_start(void)
{

        if (grptb != NULL)
                return (0);
        if (grptb_fail)
                return (-1);
        if ((grptb = (GIDC **)calloc(GNM_SZ, sizeof(GIDC *))) == NULL) {
                ++grptb_fail;
                return (-1);
        }
        return (0);
}

/*
 * user_from_uid()
 *      caches the name (if any) for the uid. If noname clear, we always
 *      return the stored name (if valid or invalid match).
 *      We use a simple hash table.
 * Return
 *      Pointer to stored name (or a empty string)
 */
const char *
user_from_uid(uid_t uid, int noname)
{
        struct passwd *pw;
        UIDC *ptr, **pptr;

        if ((uidtb == NULL) && (uidtb_start() < 0))
                return (NULL);

        /*
         * see if we have this uid cached
         */
        pptr = uidtb + (uid % UID_SZ);
        ptr = *pptr;

        if ((ptr != NULL) && (ptr->valid > 0) && (ptr->uid == uid)) {
                /*
                 * have an entry for this uid
                 */
                if (!noname || (ptr->valid == VALID))
                        return (ptr->name);
                return (NULL);
        }

        /*
         * No entry for this uid, we will add it
         */
        if (!pwopn) {
                if (_pwcache_setpassent != NULL)
                        (*_pwcache_setpassent)(1);
                ++pwopn;
        }

        if (ptr == NULL)
                *pptr = ptr = (UIDC *)malloc(sizeof(UIDC));

        if ((pw = (*_pwcache_getpwuid)(uid)) == NULL) {
                /*
                 * no match for this uid in the local password file
                 * a string that is the uid in numeric format
                 */
                if (ptr == NULL)
                        return (NULL);
                ptr->uid = uid;
                (void)snprintf(ptr->name, UNMLEN, "%lu", (long) uid);
                ptr->valid = INVALID;
                if (noname)
                        return (NULL);
        } else {
                /*
                 * there is an entry for this uid in the password file
                 */
                if (ptr == NULL)
                        return (pw->pw_name);
                ptr->uid = uid;
                (void)strlcpy(ptr->name, pw->pw_name, UNMLEN);
                ptr->valid = VALID;
        }
        return (ptr->name);
}

/*
 * group_from_gid()
 *      caches the name (if any) for the gid. If noname clear, we always
 *      return the stored name (if valid or invalid match).
 *      We use a simple hash table.
 * Return
 *      Pointer to stored name (or a empty string)
 */
const char *
group_from_gid(gid_t gid, int noname)
{
        struct group *gr;
        GIDC *ptr, **pptr;

        if ((gidtb == NULL) && (gidtb_start() < 0))
                return (NULL);

        /*
         * see if we have this gid cached
         */
        pptr = gidtb + (gid % GID_SZ);
        ptr = *pptr;

        if ((ptr != NULL) && (ptr->valid > 0) && (ptr->gid == gid)) {
                /*
                 * have an entry for this gid
                 */
                if (!noname || (ptr->valid == VALID))
                        return (ptr->name);
                return (NULL);
        }

        /*
         * No entry for this gid, we will add it
         */
        if (!gropn) {
                if (_pwcache_setgroupent != NULL)
                        (*_pwcache_setgroupent)(1);
                ++gropn;
        }

        if (ptr == NULL)
                *pptr = ptr = (GIDC *)malloc(sizeof(GIDC));

        if ((gr = (*_pwcache_getgrgid)(gid)) == NULL) {
                /*
                 * no match for this gid in the local group file, put in
                 * a string that is the gid in numeric format
                 */
                if (ptr == NULL)
                        return (NULL);
                ptr->gid = gid;
                (void)snprintf(ptr->name, GNMLEN, "%lu", (long) gid);
                ptr->valid = INVALID;
                if (noname)
                        return (NULL);
        } else {
                /*
                 * there is an entry for this group in the group file
                 */
                if (ptr == NULL)
                        return (gr->gr_name);
                ptr->gid = gid;
                (void)strlcpy(ptr->name, gr->gr_name, GNMLEN);
                ptr->valid = VALID;
        }
        return (ptr->name);
}

/*
 * uid_from_user()
 *      caches the uid for a given user name. We use a simple hash table.
 * Return
 *      the uid (if any) for a user name, or a -1 if no match can be found
 */
int
uid_from_user(const char *name, uid_t *uid)
{
        struct passwd *pw;
        UIDC *ptr, **pptr;
        size_t namelen;

        /*
         * return -1 for mangled names
         */
        if (name == NULL || ((namelen = strlen(name)) == 0))
                return (-1);
        if ((usrtb == NULL) && (usrtb_start() < 0))
                return (-1);

        /*
         * look up in hash table, if found and valid return the uid,
         * if found and invalid, return a -1
         */
        pptr = usrtb + st_hash(name, namelen, UNM_SZ);
        ptr = *pptr;

        if ((ptr != NULL) && (ptr->valid > 0) && !strcmp(name, ptr->name)) {
                if (ptr->valid == INVALID)
                        return (-1);
                *uid = ptr->uid;
                return (0);
        }

        if (!pwopn) {
                if (_pwcache_setpassent != NULL)
                        (*_pwcache_setpassent)(1);
                ++pwopn;
        }

        if (ptr == NULL)
                *pptr = ptr = (UIDC *)malloc(sizeof(UIDC));

        /*
         * no match, look it up, if no match store it as an invalid entry,
         * or store the matching uid
         */
        if (ptr == NULL) {
                if ((pw = (*_pwcache_getpwnam)(name)) == NULL)
                        return (-1);
                *uid = pw->pw_uid;
                return (0);
        }
        (void)strlcpy(ptr->name, name, UNMLEN);
        if ((pw = (*_pwcache_getpwnam)(name)) == NULL) {
                ptr->valid = INVALID;
                return (-1);
        }
        ptr->valid = VALID;
        *uid = ptr->uid = pw->pw_uid;
        return (0);
}

/*
 * gid_from_group()
 *      caches the gid for a given group name. We use a simple hash table.
 * Return
 *      the gid (if any) for a group name, or a -1 if no match can be found
 */
int
gid_from_group(const char *name, gid_t *gid)
{
        struct group *gr;
        GIDC *ptr, **pptr;
        size_t namelen;

        /*
         * return -1 for mangled names
         */
        if (name == NULL || ((namelen = strlen(name)) == 0))
                return (-1);
        if ((grptb == NULL) && (grptb_start() < 0))
                return (-1);

        /*
         * look up in hash table, if found and valid return the uid,
         * if found and invalid, return a -1
         */
        pptr = grptb + st_hash(name, namelen, GID_SZ);
        ptr = *pptr;

        if ((ptr != NULL) && (ptr->valid > 0) && !strcmp(name, ptr->name)) {
                if (ptr->valid == INVALID)
                        return (-1);
                *gid = ptr->gid;
                return (0);
        }

        if (!gropn) {
                if (_pwcache_setgroupent != NULL)
                        (*_pwcache_setgroupent)(1);
                ++gropn;
        }

        if (ptr == NULL)
                *pptr = ptr = (GIDC *)malloc(sizeof(GIDC));

        /*
         * no match, look it up, if no match store it as an invalid entry,
         * or store the matching gid
         */
        if (ptr == NULL) {
                if ((gr = (*_pwcache_getgrnam)(name)) == NULL)
                        return (-1);
                *gid = gr->gr_gid;
                return (0);
        }

        (void)strlcpy(ptr->name, name, GNMLEN);
        if ((gr = (*_pwcache_getgrnam)(name)) == NULL) {
                ptr->valid = INVALID;
                return (-1);
        }
        ptr->valid = VALID;
        *gid = ptr->gid = gr->gr_gid;
        return (0);
}

#define FLUSHTB(arr, len, fail)                         \
        do {                                            \
                if (arr != NULL) {                      \
                        for (i = 0; i < len; i++)       \
                                if (arr[i] != NULL)     \
                                        free(arr[i]);   \
                        arr = NULL;                     \
                }                                       \
                fail = 0;                               \
        } while (0)

int
pwcache_userdb(
        int             (*a_setpassent)(int),
        void            (*a_endpwent)(void),
        struct passwd * (*a_getpwnam)(const char *),
        struct passwd * (*a_getpwuid)(uid_t))
{
        int i;

                /* a_setpassent and a_endpwent may be NULL */
        if (a_getpwnam == NULL || a_getpwuid == NULL)
                return (-1);

        if (_pwcache_endpwent != NULL)
                (*_pwcache_endpwent)();
        FLUSHTB(uidtb, UID_SZ, uidtb_fail);
        FLUSHTB(usrtb, UNM_SZ, usrtb_fail);
        pwopn = 0;
        _pwcache_setpassent = a_setpassent;
        _pwcache_endpwent = a_endpwent;
        _pwcache_getpwnam = a_getpwnam;
        _pwcache_getpwuid = a_getpwuid;

        return (0);
}

int
pwcache_groupdb(
        int             (*a_setgroupent)(int),
        void            (*a_endgrent)(void),
        struct group *  (*a_getgrnam)(const char *),
        struct group *  (*a_getgrgid)(gid_t))
{
        int i;

                /* a_setgroupent and a_endgrent may be NULL */
        if (a_getgrnam == NULL || a_getgrgid == NULL)
                return (-1);

        if (_pwcache_endgrent != NULL)
                (*_pwcache_endgrent)();
        FLUSHTB(gidtb, GID_SZ, gidtb_fail);
        FLUSHTB(grptb, GNM_SZ, grptb_fail);
        gropn = 0;
        _pwcache_setgroupent = a_setgroupent;
        _pwcache_endgrent = a_endgrent;
        _pwcache_getgrnam = a_getgrnam;
        _pwcache_getgrgid = a_getgrgid;

        return (0);
}


#ifdef TEST_PWCACHE

struct passwd *
test_getpwnam(const char *name)
{
        static struct passwd foo;

        memset(&foo, 0, sizeof(foo));
        if (strcmp(name, "toor") == 0) {
                foo.pw_uid = 666;
                return &foo;
        }
        return (getpwnam(name));
}

int
main(int argc, char *argv[])
{
        uid_t   u;
        int     r, i;

        printf("pass 1 (default userdb)\n");
        for (i = 1; i < argc; i++) {
                printf("i: %d, pwopn %d usrtb_fail %d usrtb %p\n",
                    i, pwopn, usrtb_fail, usrtb);
                r = uid_from_user(argv[i], &u);
                if (r == -1)
                        printf("  uid_from_user %s: failed\n", argv[i]);
                else
                        printf("  uid_from_user %s: %d\n", argv[i], u);
        }
        printf("pass 1 finish: pwopn %d usrtb_fail %d usrtb %p\n",
                    pwopn, usrtb_fail, usrtb);

        puts("");
        printf("pass 2 (replacement userdb)\n");
        printf("pwcache_userdb returned %d\n",
            pwcache_userdb(setpassent, test_getpwnam, getpwuid));
        printf("pwopn %d usrtb_fail %d usrtb %p\n", pwopn, usrtb_fail, usrtb);

        for (i = 1; i < argc; i++) {
                printf("i: %d, pwopn %d usrtb_fail %d usrtb %p\n",
                    i, pwopn, usrtb_fail, usrtb);
                u = -1;
                r = uid_from_user(argv[i], &u);
                if (r == -1)
                        printf("  uid_from_user %s: failed\n", argv[i]);
                else
                        printf("  uid_from_user %s: %d\n", argv[i], u);
        }
        printf("pass 2 finish: pwopn %d usrtb_fail %d usrtb %p\n",
                    pwopn, usrtb_fail, usrtb);

        puts("");
        printf("pass 3 (null pointers)\n");
        printf("pwcache_userdb returned %d\n",
            pwcache_userdb(NULL, NULL, NULL));

        return (0);
}
#endif  /* TEST_PWCACHE */
#endif  /* !HAVE_PWCACHE_USERDB */