libc/gen/getpwent.c

/*-
 * Copyright (c) 2003 Networks Associates Technology, Inc.
 * All rights reserved.
 *
 * This software was developed for the FreeBSD Project by
 * Jacques A. Vidrine, Safeport Network Services, and Network
 * Associates Laboratories, the Security Research Division of Network
 * Associates, Inc. under DARPA/SPAWAR contract N66001-01-C-8035
 * ("CBOSS"), as part of the DARPA CHATS research program.
 *
 * 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 AUTHOR 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 AUTHOR 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>
__FBSDID("$FreeBSD$");

#include "namespace.h"
#include <sys/param.h>
#ifdef YP
#include <rpc/rpc.h>
#include <rpcsvc/yp_prot.h>
#include <rpcsvc/ypclnt.h>
#endif
#include <arpa/inet.h>
#include <errno.h>
#include <fcntl.h>
#ifdef HESIOD
#include <hesiod.h>
#endif
#include <netdb.h>
#include <nsswitch.h>
#include <pthread.h>
#include <pthread_np.h>
#include <pwd.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <syslog.h>
#include <unistd.h>
#include "un-namespace.h"
#include <db.h>
#include "libc_private.h"
#include "pw_scan.h"
#include "nss_tls.h"
#ifdef NS_CACHING
#include "nscache.h"
#endif

#ifndef CTASSERT
#define CTASSERT(x)             _CTASSERT(x, __LINE__)
#define _CTASSERT(x, y)         __CTASSERT(x, y)
#define __CTASSERT(x, y)        typedef char __assert_ ## y [(x) ? 1 : -1]
#endif

/* Counter as stored in /etc/pwd.db */
typedef int             pwkeynum;

CTASSERT(MAXLOGNAME > sizeof(uid_t));
CTASSERT(MAXLOGNAME > sizeof(pwkeynum));

enum constants {
        PWD_STORAGE_INITIAL     = 1 << 10, /* 1 KByte */
        PWD_STORAGE_MAX         = 1 << 20, /* 1 MByte */
        SETPWENT                = 1,
        ENDPWENT                = 2,
        HESIOD_NAME_MAX         = 256
};

static const ns_src defaultsrc[] = {
        { NSSRC_COMPAT, NS_SUCCESS },
        { NULL, 0 }
};

int     __pw_match_entry(const char *, size_t, enum nss_lookup_type,
            const char *, uid_t);
int     __pw_parse_entry(char *, size_t, struct passwd *, int, int *errnop);

static  void     pwd_init(struct passwd *);

union key {
        const char      *name;
        uid_t            uid;
};

static  struct passwd *getpw(int (*fn)(union key, struct passwd *, char *,
                    size_t, struct passwd **), union key);
static  int      wrap_getpwnam_r(union key, struct passwd *, char *,
                    size_t, struct passwd **);
static  int      wrap_getpwuid_r(union key, struct passwd *, char *, size_t,
                    struct passwd **);
static  int      wrap_getpwent_r(union key, struct passwd *, char *, size_t,
                    struct passwd **);

static  int      pwdb_match_entry_v3(char *, size_t, enum nss_lookup_type,
                    const char *, uid_t);
static  int      pwdb_parse_entry_v3(char *, size_t, struct passwd *, int *);
static  int      pwdb_match_entry_v4(char *, size_t, enum nss_lookup_type,
                    const char *, uid_t);
static  int      pwdb_parse_entry_v4(char *, size_t, struct passwd *, int *);


struct {
        int     (*match)(char *, size_t, enum nss_lookup_type, const char *,
                    uid_t);
        int     (*parse)(char *, size_t, struct passwd *, int *);
} pwdb_versions[] = {
        { NULL, NULL },                                 /* version 0 */
        { NULL, NULL },                                 /* version 1 */
        { NULL, NULL },                                 /* version 2 */
        { pwdb_match_entry_v3, pwdb_parse_entry_v3 },   /* version 3 */
        { pwdb_match_entry_v4, pwdb_parse_entry_v4 },   /* version 4 */
};


struct files_state {
        DB              *db;
        pwkeynum         keynum;
        int              stayopen;
        int              version;
};
static  void    files_endstate(void *);
NSS_TLS_HANDLING(files);
static  DB      *pwdbopen(int *);
static  void     files_endstate(void *);
static  int      files_setpwent(void *, void *, va_list);
static  int      files_passwd(void *, void *, va_list);


#ifdef HESIOD
struct dns_state {
        long    counter;
};
static  void    dns_endstate(void *);
NSS_TLS_HANDLING(dns);
static  int      dns_setpwent(void *, void *, va_list);
static  int      dns_passwd(void *, void *, va_list);
#endif


#ifdef YP
struct nis_state {
        char     domain[MAXHOSTNAMELEN];
        int      done;
        char    *key;
        int      keylen;
};
static  void     nis_endstate(void *);
NSS_TLS_HANDLING(nis);
static  int      nis_setpwent(void *, void *, va_list);
static  int      nis_passwd(void *, void *, va_list);
static  int      nis_map(char *, enum nss_lookup_type, char *, size_t, int *);
static  int      nis_adjunct(char *, const char *, char *, size_t);
#endif


struct compat_state {
        DB              *db;
        pwkeynum         keynum;
        int              stayopen;
        int              version;
        DB              *exclude;
        struct passwd    template;
        char            *name;
        enum _compat {
                COMPAT_MODE_OFF = 0,
                COMPAT_MODE_ALL,
                COMPAT_MODE_NAME,
                COMPAT_MODE_NETGROUP
        }                compat;
};
static  void     compat_endstate(void *);
NSS_TLS_HANDLING(compat);
static  int      compat_setpwent(void *, void *, va_list);
static  int      compat_passwd(void *, void *, va_list);
static  void     compat_clear_template(struct passwd *);
static  int      compat_set_template(struct passwd *, struct passwd *);
static  int      compat_use_template(struct passwd *, struct passwd *, char *,
                    size_t);
static  int      compat_redispatch(struct compat_state *, enum nss_lookup_type,
                    enum nss_lookup_type, const char *, const char *, uid_t,
                    struct passwd *, char *, size_t, int *);

#ifdef NS_CACHING
static  int      pwd_id_func(char *, size_t *, va_list ap, void *);
static  int      pwd_marshal_func(char *, size_t *, void *, va_list, void *);
static  int      pwd_unmarshal_func(char *, size_t, void *, va_list, void *);

static int
pwd_id_func(char *buffer, size_t *buffer_size, va_list ap, void *cache_mdata)
{
        char    *name;
        uid_t   uid;
        size_t  size, desired_size;
        int     res = NS_UNAVAIL;
        enum nss_lookup_type lookup_type;

        lookup_type = (enum nss_lookup_type)cache_mdata;
        switch (lookup_type) {
        case nss_lt_name:
                name = va_arg(ap, char *);
                size = strlen(name);
                desired_size = sizeof(enum nss_lookup_type) + size + 1;
                if (desired_size > *buffer_size) {
                        res = NS_RETURN;
                        goto fin;
                }

                memcpy(buffer, &lookup_type, sizeof(enum nss_lookup_type));
                memcpy(buffer + sizeof(enum nss_lookup_type), name, size + 1);

                res = NS_SUCCESS;
                break;
        case nss_lt_id:
                uid = va_arg(ap, uid_t);
                desired_size = sizeof(enum nss_lookup_type) + sizeof(uid_t);
                if (desired_size > *buffer_size) {
                        res = NS_RETURN;
                        goto fin;
                }

                memcpy(buffer, &lookup_type, sizeof(enum nss_lookup_type));
                memcpy(buffer + sizeof(enum nss_lookup_type), &uid,
                    sizeof(uid_t));

                res = NS_SUCCESS;
                break;
        default:
                /* should be unreachable */
                return (NS_UNAVAIL);
        }

fin:
        *buffer_size = desired_size;
        return (res);
}

static int
pwd_marshal_func(char *buffer, size_t *buffer_size, void *retval, va_list ap,
    void *cache_mdata)
{
        char *name;
        uid_t uid;
        struct passwd *pwd;
        char *orig_buf;
        size_t orig_buf_size;

        struct passwd new_pwd;
        size_t desired_size, size;
        char *p;

        switch ((enum nss_lookup_type)cache_mdata) {
        case nss_lt_name:
                name = va_arg(ap, char *);
                break;
        case nss_lt_id:
                uid = va_arg(ap, uid_t);
                break;
        case nss_lt_all:
                break;
        default:
                /* should be unreachable */
                return (NS_UNAVAIL);
        }

        pwd = va_arg(ap, struct passwd *);
        orig_buf = va_arg(ap, char *);
        orig_buf_size = va_arg(ap, size_t);

        desired_size = sizeof(struct passwd) + sizeof(char *) +
            strlen(pwd->pw_name) + 1;
        if (pwd->pw_passwd != NULL)
                desired_size += strlen(pwd->pw_passwd) + 1;
        if (pwd->pw_class != NULL)
                desired_size += strlen(pwd->pw_class) + 1;
        if (pwd->pw_gecos != NULL)
                desired_size += strlen(pwd->pw_gecos) + 1;
        if (pwd->pw_dir != NULL)
                desired_size += strlen(pwd->pw_dir) + 1;
        if (pwd->pw_shell != NULL)
                desired_size += strlen(pwd->pw_shell) + 1;

        if (*buffer_size < desired_size) {
                /* this assignment is here for future use */
                *buffer_size = desired_size;
                return (NS_RETURN);
        }

        memcpy(&new_pwd, pwd, sizeof(struct passwd));
        memset(buffer, 0, desired_size);

        *buffer_size = desired_size;
        p = buffer + sizeof(struct passwd) + sizeof(char *);
        memcpy(buffer + sizeof(struct passwd), &p, sizeof(char *));

        if (new_pwd.pw_name != NULL) {
                size = strlen(new_pwd.pw_name);
                memcpy(p, new_pwd.pw_name, size);
                new_pwd.pw_name = p;
                p += size + 1;
        }

        if (new_pwd.pw_passwd != NULL) {
                size = strlen(new_pwd.pw_passwd);
                memcpy(p, new_pwd.pw_passwd, size);
                new_pwd.pw_passwd = p;
                p += size + 1;
        }

        if (new_pwd.pw_class != NULL) {
                size = strlen(new_pwd.pw_class);
                memcpy(p, new_pwd.pw_class, size);
                new_pwd.pw_class = p;
                p += size + 1;
        }

        if (new_pwd.pw_gecos != NULL) {
                size = strlen(new_pwd.pw_gecos);
                memcpy(p, new_pwd.pw_gecos, size);
                new_pwd.pw_gecos = p;
                p += size + 1;
        }

        if (new_pwd.pw_dir != NULL) {
                size = strlen(new_pwd.pw_dir);
                memcpy(p, new_pwd.pw_dir, size);
                new_pwd.pw_dir = p;
                p += size + 1;
        }

        if (new_pwd.pw_shell != NULL) {
                size = strlen(new_pwd.pw_shell);
                memcpy(p, new_pwd.pw_shell, size);
                new_pwd.pw_shell = p;
                p += size + 1;
        }

        memcpy(buffer, &new_pwd, sizeof(struct passwd));
        return (NS_SUCCESS);
}

static int
pwd_unmarshal_func(char *buffer, size_t buffer_size, void *retval, va_list ap,
    void *cache_mdata)
{
        char *name;
        uid_t uid;
        struct passwd *pwd;
        char *orig_buf;
        size_t orig_buf_size;
        int *ret_errno;

        char *p;

        switch ((enum nss_lookup_type)cache_mdata) {
        case nss_lt_name:
                name = va_arg(ap, char *);
                break;
        case nss_lt_id:
                uid = va_arg(ap, uid_t);
                break;
        case nss_lt_all:
                break;
        default:
                /* should be unreachable */
                return (NS_UNAVAIL);
        }

        pwd = va_arg(ap, struct passwd *);
        orig_buf = va_arg(ap, char *);
        orig_buf_size = va_arg(ap, size_t);
        ret_errno = va_arg(ap, int *);

        if (orig_buf_size <
            buffer_size - sizeof(struct passwd) - sizeof(char *)) {
                *ret_errno = ERANGE;
                return (NS_RETURN);
        }

        memcpy(pwd, buffer, sizeof(struct passwd));
        memcpy(&p, buffer + sizeof(struct passwd), sizeof(char *));
        memcpy(orig_buf, buffer + sizeof(struct passwd) + sizeof(char *),
            buffer_size - sizeof(struct passwd) - sizeof(char *));

        NS_APPLY_OFFSET(pwd->pw_name, orig_buf, p, char *);
        NS_APPLY_OFFSET(pwd->pw_passwd, orig_buf, p, char *);
        NS_APPLY_OFFSET(pwd->pw_class, orig_buf, p, char *);
        NS_APPLY_OFFSET(pwd->pw_gecos, orig_buf, p, char *);
        NS_APPLY_OFFSET(pwd->pw_dir, orig_buf, p, char *);
        NS_APPLY_OFFSET(pwd->pw_shell, orig_buf, p, char *);

        if (retval != NULL)
                *((struct passwd **)retval) = pwd;

        return (NS_SUCCESS);
}

NSS_MP_CACHE_HANDLING(passwd);
#endif /* NS_CACHING */

void
setpwent(void)
{
#ifdef NS_CACHING
        static const nss_cache_info cache_info = NS_MP_CACHE_INFO_INITIALIZER(
                passwd, (void *)nss_lt_all,
                NULL, NULL);
#endif

        static const ns_dtab dtab[] = {
                { NSSRC_FILES, files_setpwent, (void *)SETPWENT },
#ifdef HESIOD
                { NSSRC_DNS, dns_setpwent, (void *)SETPWENT },
#endif
#ifdef YP
                { NSSRC_NIS, nis_setpwent, (void *)SETPWENT },
#endif
                { NSSRC_COMPAT, compat_setpwent, (void *)SETPWENT },
#ifdef NS_CACHING
                NS_CACHE_CB(&cache_info)
#endif
                { NULL, NULL, NULL }
        };
        (void)_nsdispatch(NULL, dtab, NSDB_PASSWD, "setpwent", defaultsrc, 0);
}


int
setpassent(int stayopen)
{
#ifdef NS_CACHING
        static const nss_cache_info cache_info = NS_MP_CACHE_INFO_INITIALIZER(
                passwd, (void *)nss_lt_all,
                NULL, NULL);
#endif

        static const ns_dtab dtab[] = {
                { NSSRC_FILES, files_setpwent, (void *)SETPWENT },
#ifdef HESIOD
                { NSSRC_DNS, dns_setpwent, (void *)SETPWENT },
#endif
#ifdef YP
                { NSSRC_NIS, nis_setpwent, (void *)SETPWENT },
#endif
                { NSSRC_COMPAT, compat_setpwent, (void *)SETPWENT },
#ifdef NS_CACHING
                NS_CACHE_CB(&cache_info)
#endif
                { NULL, NULL, NULL }
        };
        (void)_nsdispatch(NULL, dtab, NSDB_PASSWD, "setpwent", defaultsrc,
            stayopen);
        return (1);
}


void
endpwent(void)
{
#ifdef NS_CACHING
        static const nss_cache_info cache_info = NS_MP_CACHE_INFO_INITIALIZER(
                passwd, (void *)nss_lt_all,
                NULL, NULL);
#endif

        static const ns_dtab dtab[] = {
                { NSSRC_FILES, files_setpwent, (void *)ENDPWENT },
#ifdef HESIOD
                { NSSRC_DNS, dns_setpwent, (void *)ENDPWENT },
#endif
#ifdef YP
                { NSSRC_NIS, nis_setpwent, (void *)ENDPWENT },
#endif
                { NSSRC_COMPAT, compat_setpwent, (void *)ENDPWENT },
#ifdef NS_CACHING
                NS_CACHE_CB(&cache_info)
#endif
                { NULL, NULL, NULL }
        };
        (void)_nsdispatch(NULL, dtab, NSDB_PASSWD, "endpwent", defaultsrc);
}


int
getpwent_r(struct passwd *pwd, char *buffer, size_t bufsize,
    struct passwd **result)
{
#ifdef NS_CACHING
        static const nss_cache_info cache_info = NS_MP_CACHE_INFO_INITIALIZER(
                passwd, (void *)nss_lt_all,
                pwd_marshal_func, pwd_unmarshal_func);
#endif

        static const ns_dtab dtab[] = {
                { NSSRC_FILES, files_passwd, (void *)nss_lt_all },
#ifdef HESIOD
                { NSSRC_DNS, dns_passwd, (void *)nss_lt_all },
#endif
#ifdef YP
                { NSSRC_NIS, nis_passwd, (void *)nss_lt_all },
#endif
                { NSSRC_COMPAT, compat_passwd, (void *)nss_lt_all },
#ifdef NS_CACHING
                NS_CACHE_CB(&cache_info)
#endif
                { NULL, NULL, NULL }
        };
        int     rv, ret_errno;

        pwd_init(pwd);
        ret_errno = 0;
        *result = NULL;
        rv = _nsdispatch(result, dtab, NSDB_PASSWD, "getpwent_r", defaultsrc,
            pwd, buffer, bufsize, &ret_errno);
        if (rv == NS_SUCCESS)
                return (0);
        else
                return (ret_errno);
}


int
getpwnam_r(const char *name, struct passwd *pwd, char *buffer, size_t bufsize,
    struct passwd **result)
{
#ifdef NS_CACHING
        static const nss_cache_info cache_info =
                NS_COMMON_CACHE_INFO_INITIALIZER(
                passwd, (void *)nss_lt_name,
                pwd_id_func, pwd_marshal_func, pwd_unmarshal_func);
#endif

        static const ns_dtab dtab[] = {
                { NSSRC_FILES, files_passwd, (void *)nss_lt_name },
#ifdef HESIOD
                { NSSRC_DNS, dns_passwd, (void *)nss_lt_name },
#endif
#ifdef YP
                { NSSRC_NIS, nis_passwd, (void *)nss_lt_name },
#endif
                { NSSRC_COMPAT, compat_passwd, (void *)nss_lt_name },
#ifdef NS_CACHING
                NS_CACHE_CB(&cache_info)
#endif
                { NULL, NULL, NULL }
        };
        int     rv, ret_errno;

        pwd_init(pwd);
        ret_errno = 0;
        *result = NULL;
        rv = _nsdispatch(result, dtab, NSDB_PASSWD, "getpwnam_r", defaultsrc,
            name, pwd, buffer, bufsize, &ret_errno);
        if (rv == NS_SUCCESS)
                return (0);
        else
                return (ret_errno);
}


int
getpwuid_r(uid_t uid, struct passwd *pwd, char *buffer, size_t bufsize,
    struct passwd **result)
{
#ifdef NS_CACHING
        static const nss_cache_info cache_info =
                NS_COMMON_CACHE_INFO_INITIALIZER(
                passwd, (void *)nss_lt_id,
                pwd_id_func, pwd_marshal_func, pwd_unmarshal_func);
#endif

        static const ns_dtab dtab[] = {
                { NSSRC_FILES, files_passwd, (void *)nss_lt_id },
#ifdef HESIOD
                { NSSRC_DNS, dns_passwd, (void *)nss_lt_id },
#endif
#ifdef YP
                { NSSRC_NIS, nis_passwd, (void *)nss_lt_id },
#endif
                { NSSRC_COMPAT, compat_passwd, (void *)nss_lt_id },
#ifdef NS_CACHING
                NS_CACHE_CB(&cache_info)
#endif
                { NULL, NULL, NULL }
        };
        int     rv, ret_errno;

        pwd_init(pwd);
        ret_errno = 0;
        *result = NULL;
        rv = _nsdispatch(result, dtab, NSDB_PASSWD, "getpwuid_r", defaultsrc,
            uid, pwd, buffer, bufsize, &ret_errno);
        if (rv == NS_SUCCESS)
                return (0);
        else
                return (ret_errno);
}


static void
pwd_init(struct passwd *pwd)
{
        static char nul[] = "";

        memset(pwd, 0, sizeof(*pwd));
        pwd->pw_uid = (uid_t)-1;  /* Considered least likely to lead to */
        pwd->pw_gid = (gid_t)-1;  /* a security issue.                  */
        pwd->pw_name = nul;
        pwd->pw_passwd = nul;
        pwd->pw_class = nul;
        pwd->pw_gecos = nul;
        pwd->pw_dir = nul;
        pwd->pw_shell = nul;
}


static struct passwd     pwd;
static char             *pwd_storage;
static size_t            pwd_storage_size;


static struct passwd *
getpw(int (*fn)(union key, struct passwd *, char *, size_t, struct passwd **),
    union key key)
{
        int              rv;
        struct passwd   *res;

        if (pwd_storage == NULL) {
                pwd_storage = malloc(PWD_STORAGE_INITIAL);
                if (pwd_storage == NULL)
                        return (NULL);
                pwd_storage_size = PWD_STORAGE_INITIAL;
        }
        do {
                rv = fn(key, &pwd, pwd_storage, pwd_storage_size, &res);
                if (res == NULL && rv == ERANGE) {
                        free(pwd_storage);
                        if ((pwd_storage_size << 1) > PWD_STORAGE_MAX) {
                                pwd_storage = NULL;
                                errno = ERANGE;
                                return (NULL);
                        }
                        pwd_storage_size <<= 1;
                        pwd_storage = malloc(pwd_storage_size);
                        if (pwd_storage == NULL)
                                return (NULL);
                }
        } while (res == NULL && rv == ERANGE);
        if (rv != 0)
                errno = rv;
        return (res);
}


static int
wrap_getpwnam_r(union key key, struct passwd *pwd, char *buffer,
    size_t bufsize, struct passwd **res)
{
        return (getpwnam_r(key.name, pwd, buffer, bufsize, res));
}


static int
wrap_getpwuid_r(union key key, struct passwd *pwd, char *buffer,
    size_t bufsize, struct passwd **res)
{
        return (getpwuid_r(key.uid, pwd, buffer, bufsize, res));
}


static int
wrap_getpwent_r(union key key __unused, struct passwd *pwd, char *buffer,
    size_t bufsize, struct passwd **res)
{
        return (getpwent_r(pwd, buffer, bufsize, res));
}


struct passwd *
getpwnam(const char *name)
{
        union key key;

        key.name = name;
        return (getpw(wrap_getpwnam_r, key));
}


struct passwd *
getpwuid(uid_t uid)
{
        union key key;

        key.uid = uid;
        return (getpw(wrap_getpwuid_r, key));
}


struct passwd *
getpwent(void)
{
        union key key;

        key.uid = 0; /* not used */
        return (getpw(wrap_getpwent_r, key));
}


/*
 * files backend
 */
static DB *
pwdbopen(int *version)
{
        DB      *res;
        DBT      key, entry;
        int      rv;

        if (geteuid() != 0 ||
            (res = dbopen(_PATH_SMP_DB, O_RDONLY, 0, DB_HASH, NULL)) == NULL)
                res = dbopen(_PATH_MP_DB, O_RDONLY, 0, DB_HASH, NULL);
        if (res == NULL)
                return (NULL);
        key.data = _PWD_VERSION_KEY;
        key.size = strlen(_PWD_VERSION_KEY);
        rv = res->get(res, &key, &entry, 0);
        if (rv == 0)
                *version = *(unsigned char *)entry.data;
        else
                *version = 3;
        if (*version < 3 ||
            *version >= nitems(pwdb_versions)) {
                syslog(LOG_CRIT, "Unsupported password database version %d",
                    *version);
                res->close(res);
                res = NULL;
        }
        return (res);
}


static void
files_endstate(void *p)
{
        DB      *db;

        if (p == NULL)
                return;
        db = ((struct files_state *)p)->db;
        if (db != NULL)
                db->close(db);
        free(p);
}


static int
files_setpwent(void *retval, void *mdata, va_list ap)
{
        struct files_state      *st;
        int                      rv, stayopen;

        rv = files_getstate(&st);
        if (rv != 0)
                return (NS_UNAVAIL);
        switch ((enum constants)mdata) {
        case SETPWENT:
                stayopen = va_arg(ap, int);
                st->keynum = 0;
                if (stayopen)
                        st->db = pwdbopen(&st->version);
                st->stayopen = stayopen;
                break;
        case ENDPWENT:
                if (st->db != NULL) {
                        (void)st->db->close(st->db);
                        st->db = NULL;
                }
                break;
        default:
                break;
        }
        return (NS_UNAVAIL);
}


static int
files_passwd(void *retval, void *mdata, va_list ap)
{
        char                     keybuf[MAXLOGNAME + 1];
        DBT                      key, entry;
        struct files_state      *st;
        enum nss_lookup_type     how;
        const char              *name;
        struct passwd           *pwd;
        char                    *buffer;
        size_t                   bufsize, namesize;
        uid_t                    uid;
        uint32_t                 store;
        int                      rv, stayopen = 0, *errnop;

        name = NULL;
        uid = (uid_t)-1;
        how = (enum nss_lookup_type)mdata;
        switch (how) {
        case nss_lt_name:
                name = va_arg(ap, const char *);
                keybuf[0] = _PW_KEYBYNAME;
                break;
        case nss_lt_id:
                uid = va_arg(ap, uid_t);
                keybuf[0] = _PW_KEYBYUID;
                break;
        case nss_lt_all:
                keybuf[0] = _PW_KEYBYNUM;
                break;
        default:
                rv = NS_NOTFOUND;
                goto fin;
        }
        pwd = va_arg(ap, struct passwd *);
        buffer = va_arg(ap, char *);
        bufsize = va_arg(ap, size_t);
        errnop = va_arg(ap, int *);
        *errnop = files_getstate(&st);
        if (*errnop != 0)
                return (NS_UNAVAIL);
        if (how == nss_lt_all && st->keynum < 0) {
                rv = NS_NOTFOUND;
                goto fin;
        }
        if (st->db == NULL &&
            (st->db = pwdbopen(&st->version)) == NULL) {
                *errnop = errno;
                rv = NS_UNAVAIL;
                goto fin;
        }
        if (how == nss_lt_all)
                stayopen = 1;
        else
                stayopen = st->stayopen;
        key.data = keybuf;
        do {
                switch (how) {
                case nss_lt_name:
                        /* MAXLOGNAME includes NUL byte, but we do not
                         * include the NUL byte in the key.
                         */
                        namesize = strlcpy(&keybuf[1], name, sizeof(keybuf)-1);
                        if (namesize >= sizeof(keybuf)-1) {
                                *errnop = EINVAL;
                                rv = NS_NOTFOUND;
                                goto fin;
                        }
                        key.size = namesize + 1;
                        break;
                case nss_lt_id:
                        if (st->version < _PWD_CURRENT_VERSION) {
                                memcpy(&keybuf[1], &uid, sizeof(uid));
                                key.size = sizeof(uid) + 1;
                        } else {
                                store = htonl(uid);
                                memcpy(&keybuf[1], &store, sizeof(store));
                                key.size = sizeof(store) + 1;
                        }
                        break;
                case nss_lt_all:
                        st->keynum++;
                        if (st->version < _PWD_CURRENT_VERSION) {
                                memcpy(&keybuf[1], &st->keynum,
                                    sizeof(st->keynum));
                                key.size = sizeof(st->keynum) + 1;
                        } else {
                                store = htonl(st->keynum);
                                memcpy(&keybuf[1], &store, sizeof(store));
                                key.size = sizeof(store) + 1;
                        }
                        break;
                }
                keybuf[0] = _PW_VERSIONED(keybuf[0], st->version);
                rv = st->db->get(st->db, &key, &entry, 0);
                if (rv < 0 || rv > 1) { /* should never return > 1 */
                        *errnop = errno;
                        rv = NS_UNAVAIL;
                        goto fin;
                } else if (rv == 1) {
                        if (how == nss_lt_all)
                                st->keynum = -1;
                        rv = NS_NOTFOUND;
                        goto fin;
                }
                rv = pwdb_versions[st->version].match(entry.data, entry.size,
                    how, name, uid);
                if (rv != NS_SUCCESS)
                        continue;
                if (entry.size > bufsize) {
                        *errnop = ERANGE;
                        rv = NS_RETURN;
                        break;
                }
                memcpy(buffer, entry.data, entry.size);
                rv = pwdb_versions[st->version].parse(buffer, entry.size, pwd,
                    errnop);
        } while (how == nss_lt_all && !(rv & NS_TERMINATE));
fin:
        if (st->db != NULL && !stayopen) {
                (void)st->db->close(st->db);
                st->db = NULL;
        }
        if (rv == NS_SUCCESS) {
                pwd->pw_fields &= ~_PWF_SOURCE;
                pwd->pw_fields |= _PWF_FILES;
                if (retval != NULL)
                        *(struct passwd **)retval = pwd;
        }
        return (rv);
}


static int
pwdb_match_entry_v3(char *entry, size_t entrysize, enum nss_lookup_type how,
    const char *name, uid_t uid)
{
        const char      *p, *eom;
        uid_t            uid2;

        eom = &entry[entrysize];
        for (p = entry; p < eom; p++)
                if (*p == '\0')
                        break;
        if (*p != '\0')
                return (NS_NOTFOUND);
        if (how == nss_lt_all)
                return (NS_SUCCESS);
        if (how == nss_lt_name)
                return (strcmp(name, entry) == 0 ? NS_SUCCESS : NS_NOTFOUND);
        for (p++; p < eom; p++)
                if (*p == '\0')
                        break;
        if (*p != '\0' || (++p) + sizeof(uid) >= eom)
                return (NS_NOTFOUND);
        memcpy(&uid2, p, sizeof(uid2));
        return (uid == uid2 ? NS_SUCCESS : NS_NOTFOUND);
}


static int
pwdb_parse_entry_v3(char *buffer, size_t bufsize, struct passwd *pwd,
    int *errnop)
{
        char            *p, *eom;
        int32_t          pw_change, pw_expire;

        /* THIS CODE MUST MATCH THAT IN pwd_mkdb. */
        p = buffer;
        eom = &buffer[bufsize];
#define STRING(field)   do {                    \
                (field) = p;                    \
                while (p < eom && *p != '\0')   \
                        p++;                    \
                if (p >= eom)                   \
                        return (NS_NOTFOUND);   \
                p++;                            \
        } while (0)
#define SCALAR(field)   do {                            \
                if (p + sizeof(field) > eom)            \
                        return (NS_NOTFOUND);           \
                memcpy(&(field), p, sizeof(field));     \
                p += sizeof(field);                     \
        } while (0)
        STRING(pwd->pw_name);
        STRING(pwd->pw_passwd);
        SCALAR(pwd->pw_uid);
        SCALAR(pwd->pw_gid);
        SCALAR(pw_change);
        STRING(pwd->pw_class);
        STRING(pwd->pw_gecos);
        STRING(pwd->pw_dir);
        STRING(pwd->pw_shell);
        SCALAR(pw_expire);
        SCALAR(pwd->pw_fields);
#undef STRING
#undef SCALAR
        pwd->pw_change = pw_change;
        pwd->pw_expire = pw_expire;
        return (NS_SUCCESS);
}


static int
pwdb_match_entry_v4(char *entry, size_t entrysize, enum nss_lookup_type how,
    const char *name, uid_t uid)
{
        const char      *p, *eom;
        uint32_t         uid2;

        eom = &entry[entrysize];
        for (p = entry; p < eom; p++)
                if (*p == '\0')
                        break;
        if (*p != '\0')
                return (NS_NOTFOUND);
        if (how == nss_lt_all)
                return (NS_SUCCESS);
        if (how == nss_lt_name)
                return (strcmp(name, entry) == 0 ? NS_SUCCESS : NS_NOTFOUND);
        for (p++; p < eom; p++)
                if (*p == '\0')
                        break;
        if (*p != '\0' || (++p) + sizeof(uid) >= eom)
                return (NS_NOTFOUND);
        memcpy(&uid2, p, sizeof(uid2));
        uid2 = ntohl(uid2);
        return (uid == (uid_t)uid2 ? NS_SUCCESS : NS_NOTFOUND);
}


static int
pwdb_parse_entry_v4(char *buffer, size_t bufsize, struct passwd *pwd,
    int *errnop)
{
        char            *p, *eom;
        uint32_t         n;

        /* THIS CODE MUST MATCH THAT IN pwd_mkdb. */
        p = buffer;
        eom = &buffer[bufsize];
#define STRING(field)   do {                    \
                (field) = p;                    \
                while (p < eom && *p != '\0')   \
                        p++;                    \
                if (p >= eom)                   \
                        return (NS_NOTFOUND);   \
                p++;                            \
        } while (0)
#define SCALAR(field)   do {                            \
                if (p + sizeof(n) > eom)                \
                        return (NS_NOTFOUND);           \
                memcpy(&n, p, sizeof(n));               \
                (field) = ntohl(n);                     \
                p += sizeof(n);                         \
        } while (0)
        STRING(pwd->pw_name);
        STRING(pwd->pw_passwd);
        SCALAR(pwd->pw_uid);
        SCALAR(pwd->pw_gid);
        SCALAR(pwd->pw_change);
        STRING(pwd->pw_class);
        STRING(pwd->pw_gecos);
        STRING(pwd->pw_dir);
        STRING(pwd->pw_shell);
        SCALAR(pwd->pw_expire);
        SCALAR(pwd->pw_fields);
#undef STRING
#undef SCALAR
        return (NS_SUCCESS);
}


#ifdef HESIOD
/*
 * dns backend
 */
static void
dns_endstate(void *p)
{
        free(p);
}


static int
dns_setpwent(void *retval, void *mdata, va_list ap)
{
        struct dns_state        *st;
        int                      rv;

        rv = dns_getstate(&st);
        if (rv != 0)
                return (NS_UNAVAIL);
        st->counter = 0;
        return (NS_UNAVAIL);
}


static int
dns_passwd(void *retval, void *mdata, va_list ap)
{
        char                     buf[HESIOD_NAME_MAX];
        struct dns_state        *st;
        struct passwd           *pwd;
        const char              *name, *label;
        void                    *ctx;
        char                    *buffer, **hes;
        size_t                   bufsize, linesize;
        uid_t                    uid;
        enum nss_lookup_type     how;
        int                      rv, *errnop;

        ctx = NULL;
        hes = NULL;
        name = NULL;
        uid = (uid_t)-1;
        how = (enum nss_lookup_type)mdata;
        switch (how) {
        case nss_lt_name:
                name = va_arg(ap, const char *);
                break;
        case nss_lt_id:
                uid = va_arg(ap, uid_t);
                break;
        case nss_lt_all:
                break;
        }
        pwd     = va_arg(ap, struct passwd *);
        buffer  = va_arg(ap, char *);
        bufsize = va_arg(ap, size_t);
        errnop  = va_arg(ap, int *);
        *errnop = dns_getstate(&st);
        if (*errnop != 0)
                return (NS_UNAVAIL);
        if (hesiod_init(&ctx) != 0) {
                *errnop = errno;
                rv = NS_UNAVAIL;
                goto fin;
        }
        do {
                rv = NS_NOTFOUND;
                switch (how) {
                case nss_lt_name:
                        label = name;
                        break;
                case nss_lt_id:
                        if (snprintf(buf, sizeof(buf), "%lu",
                            (unsigned long)uid) >= sizeof(buf))
                                goto fin;
                        label = buf;
                        break;
                case nss_lt_all:
                        if (st->counter < 0)
                                goto fin;
                        if (snprintf(buf, sizeof(buf), "passwd-%ld",
                            st->counter++) >= sizeof(buf))
                                goto fin;
                        label = buf;
                        break;
                }
                hes = hesiod_resolve(ctx, label,
                    how == nss_lt_id ? "uid" : "passwd");
                if (hes == NULL) {
                        if (how == nss_lt_all)
                                st->counter = -1;
                        if (errno != ENOENT)
                                *errnop = errno;
                        goto fin;
                }
                rv = __pw_match_entry(hes[0], strlen(hes[0]), how, name, uid);
                if (rv != NS_SUCCESS) {
                        hesiod_free_list(ctx, hes);
                        hes = NULL;
                        continue;
                }
                linesize = strlcpy(buffer, hes[0], bufsize);
                if (linesize >= bufsize) {
                        *errnop = ERANGE;
                        rv = NS_RETURN;
                        continue;
                }
                hesiod_free_list(ctx, hes);
                hes = NULL;
                rv = __pw_parse_entry(buffer, bufsize, pwd, 0, errnop);
        } while (how == nss_lt_all && !(rv & NS_TERMINATE));
fin:
        if (hes != NULL)
                hesiod_free_list(ctx, hes);
        if (ctx != NULL)
                hesiod_end(ctx);
        if (rv == NS_SUCCESS) {
                pwd->pw_fields &= ~_PWF_SOURCE;
                pwd->pw_fields |= _PWF_HESIOD;
                if (retval != NULL)
                        *(struct passwd **)retval = pwd;
        }
        return (rv);
}
#endif /* HESIOD */


#ifdef YP
/*
 * nis backend
 */
static void
nis_endstate(void *p)
{
        free(((struct nis_state *)p)->key);
        free(p);
}

/*
 * Test for the presence of special FreeBSD-specific master.passwd.by*
 * maps. We do this using yp_order(). If it fails, then either the server
 * doesn't have the map, or the YPPROC_ORDER procedure isn't supported by
 * the server (Sun NIS+ servers in YP compat mode behave this way). If
 * the master.passwd.by* maps don't exist, then let the lookup routine try
 * the regular passwd.by* maps instead. If the lookup routine fails, it
 * can return an error as needed.
 */
static int
nis_map(char *domain, enum nss_lookup_type how, char *buffer, size_t bufsize,
    int *master)
{
        int     rv, order;

        *master = 0;
        if (geteuid() == 0) {
                if (snprintf(buffer, bufsize, "master.passwd.by%s",
                    (how == nss_lt_id) ? "uid" : "name") >= bufsize)
                        return (NS_UNAVAIL);
                rv = yp_order(domain, buffer, &order);
                if (rv == 0) {
                        *master = 1;
                        return (NS_SUCCESS);
                }
        }

        if (snprintf(buffer, bufsize, "passwd.by%s",
            (how == nss_lt_id) ? "uid" : "name") >= bufsize)
                return (NS_UNAVAIL);

        return (NS_SUCCESS);
}


static int
nis_adjunct(char *domain, const char *name, char *buffer, size_t bufsize)
{
        int      rv;
        char    *result, *p, *q, *eor;
        int      resultlen;

        result = NULL;
        rv = yp_match(domain, "passwd.adjunct.byname", name, strlen(name),
            &result, &resultlen);
        if (rv != 0)
                rv = 1;
        else {
                eor = &result[resultlen];
                p = memchr(result, ':', eor - result);
                if (p != NULL && ++p < eor &&
                    (q = memchr(p, ':', eor - p)) != NULL) {
                        if (q - p >= bufsize)
                                rv = -1;
                        else {
                                memcpy(buffer, p, q - p);
                                buffer[q - p] ='\0';
                        }
                } else
                        rv = 1;
        }
        free(result);
        return (rv);
}


static int
nis_setpwent(void *retval, void *mdata, va_list ap)
{
        struct nis_state        *st;
        int                      rv;

        rv = nis_getstate(&st);
        if (rv != 0)
                return (NS_UNAVAIL);
        st->done = 0;
        free(st->key);
        st->key = NULL;
        return (NS_UNAVAIL);
}


static int
nis_passwd(void *retval, void *mdata, va_list ap)
{
        char             map[YPMAXMAP];
        struct nis_state *st;
        struct passwd   *pwd;
        const char      *name;
        char            *buffer, *key, *result;
        size_t           bufsize;
        uid_t            uid;
        enum nss_lookup_type how;
        int             *errnop, keylen, resultlen, rv, master;

        name = NULL;
        uid = (uid_t)-1;
        how = (enum nss_lookup_type)mdata;
        switch (how) {
        case nss_lt_name:
                name = va_arg(ap, const char *);
                break;
        case nss_lt_id:
                uid = va_arg(ap, uid_t);
                break;
        case nss_lt_all:
                break;
        }
        pwd     = va_arg(ap, struct passwd *);
        buffer  = va_arg(ap, char *);
        bufsize = va_arg(ap, size_t);
        errnop  = va_arg(ap, int *);
        *errnop = nis_getstate(&st);
        if (*errnop != 0)
                return (NS_UNAVAIL);
        if (st->domain[0] == '\0') {
                if (getdomainname(st->domain, sizeof(st->domain)) != 0) {
                        *errnop = errno;
                        return (NS_UNAVAIL);
                }
        }
        rv = nis_map(st->domain, how, map, sizeof(map), &master);
        if (rv != NS_SUCCESS)
                return (rv);
        result = NULL;
        do {
                rv = NS_NOTFOUND;
                switch (how) {
                case nss_lt_name:
                        if (strlcpy(buffer, name, bufsize) >= bufsize)
                                goto erange;
                        break;
                case nss_lt_id:
                        if (snprintf(buffer, bufsize, "%lu",
                            (unsigned long)uid) >= bufsize)
                                goto erange;
                        break;
                case nss_lt_all:
                        if (st->done)
                                goto fin;
                        break;
                }
                result = NULL;
                if (how == nss_lt_all) {
                        if (st->key == NULL)
                                rv = yp_first(st->domain, map, &st->key,
                                    &st->keylen, &result, &resultlen);
                        else {
                                key = st->key;
                                keylen = st->keylen;
                                st->key = NULL;
                                rv = yp_next(st->domain, map, key, keylen,
                                    &st->key, &st->keylen, &result,
                                    &resultlen);
                                free(key);
                        }
                        if (rv != 0) {
                                free(result);
                                free(st->key);
                                st->key = NULL;
                                if (rv == YPERR_NOMORE)
                                        st->done = 1;
                                else
                                        rv = NS_UNAVAIL;
                                goto fin;
                        }
                } else {
                        rv = yp_match(st->domain, map, buffer, strlen(buffer),
                            &result, &resultlen);
                        if (rv == YPERR_KEY) {
                                rv = NS_NOTFOUND;
                                continue;
                        } else if (rv != 0) {
                                free(result);
                                rv = NS_UNAVAIL;
                                continue;
                        }
                }
                if (resultlen >= bufsize) {
                        free(result);
                        goto erange;
                }
                memcpy(buffer, result, resultlen);
                buffer[resultlen] = '\0';
                free(result);
                rv = __pw_match_entry(buffer, resultlen, how, name, uid);
                if (rv == NS_SUCCESS)
                        rv = __pw_parse_entry(buffer, resultlen, pwd, master,
                            errnop);
        } while (how == nss_lt_all && !(rv & NS_TERMINATE));
fin:
        if (rv == NS_SUCCESS) {
                if (strstr(pwd->pw_passwd, "##") != NULL) {
                        rv = nis_adjunct(st->domain, pwd->pw_name,
                            &buffer[resultlen+1], bufsize-resultlen-1);
                        if (rv < 0)
                                goto erange;
                        else if (rv == 0)
                                pwd->pw_passwd = &buffer[resultlen+1];
                }
                pwd->pw_fields &= ~_PWF_SOURCE;
                pwd->pw_fields |= _PWF_NIS;
                if (retval != NULL)
                        *(struct passwd **)retval = pwd;
                rv = NS_SUCCESS;
        }
        return (rv);
erange:
        *errnop = ERANGE;
        return (NS_RETURN);
}
#endif /* YP */


/*
 * compat backend
 */
static void
compat_clear_template(struct passwd *template)
{

        free(template->pw_passwd);
        free(template->pw_gecos);
        free(template->pw_dir);
        free(template->pw_shell);
        memset(template, 0, sizeof(*template));
}


static int
compat_set_template(struct passwd *src, struct passwd *template)
{

        compat_clear_template(template);
#ifdef PW_OVERRIDE_PASSWD
        if ((src->pw_fields & _PWF_PASSWD) &&
            (template->pw_passwd = strdup(src->pw_passwd)) == NULL)
                goto enomem;
#endif
        if (src->pw_fields & _PWF_UID)
                template->pw_uid = src->pw_uid;
        if (src->pw_fields & _PWF_GID)
                template->pw_gid = src->pw_gid;
        if ((src->pw_fields & _PWF_GECOS) &&
            (template->pw_gecos = strdup(src->pw_gecos)) == NULL)
                goto enomem;
        if ((src->pw_fields & _PWF_DIR) &&
            (template->pw_dir = strdup(src->pw_dir)) == NULL)
                goto enomem;
        if ((src->pw_fields & _PWF_SHELL) &&
            (template->pw_shell = strdup(src->pw_shell)) == NULL)
                goto enomem;
        template->pw_fields = src->pw_fields;
        return (0);
enomem:
        syslog(LOG_ERR, "getpwent memory allocation failure");
        return (-1);
}


static int
compat_use_template(struct passwd *pwd, struct passwd *template, char *buffer,
    size_t bufsize)
{
        struct passwd hold;
        char    *copy, *p, *q, *eob;
        size_t   n;

        /* We cannot know the layout of the password fields in `buffer',
         * so we have to copy everything.
         */
        if (template->pw_fields == 0) /* nothing to fill-in */
                return (0);
        n = 0;
        n += pwd->pw_name != NULL ? strlen(pwd->pw_name) + 1 : 0;
        n += pwd->pw_passwd != NULL ? strlen(pwd->pw_passwd) + 1 : 0;
        n += pwd->pw_class != NULL ? strlen(pwd->pw_class) + 1 : 0;
        n += pwd->pw_gecos != NULL ? strlen(pwd->pw_gecos) + 1 : 0;
        n += pwd->pw_dir != NULL ? strlen(pwd->pw_dir) + 1 : 0;
        n += pwd->pw_shell != NULL ? strlen(pwd->pw_shell) + 1 : 0;
        copy = malloc(n);
        if (copy == NULL) {
                syslog(LOG_ERR, "getpwent memory allocation failure");
                return (ENOMEM);
        }
        p = copy;
        eob = &copy[n];
#define COPY(field) do {                                \
        if (pwd->field == NULL)                         \
                hold.field = NULL;                      \
        else {                                          \
                hold.field = p;                         \
                p += strlcpy(p, pwd->field, eob-p) + 1; \
        }                                               \
} while (0)
        COPY(pw_name);
        COPY(pw_passwd);
        COPY(pw_class);
        COPY(pw_gecos);
        COPY(pw_dir);
        COPY(pw_shell);
#undef COPY
        p = buffer;
        eob = &buffer[bufsize];
#define COPY(field, flag) do {                                           \
        q = (template->pw_fields & flag) ? template->field : hold.field; \
        if (q == NULL)                                                   \
                pwd->field = NULL;                                       \
        else {                                                           \
                pwd->field = p;                                          \
                if ((n = strlcpy(p, q, eob-p)) >= eob-p) {               \
                        free(copy);                                      \
                        return (ERANGE);                                 \
                }                                                        \
                p += n + 1;                                              \
        }                                                                \
} while (0)
        COPY(pw_name, 0);
#ifdef PW_OVERRIDE_PASSWD
        COPY(pw_passwd, _PWF_PASSWD);
#else
        COPY(pw_passwd, 0);
#endif
        COPY(pw_class, 0);
        COPY(pw_gecos, _PWF_GECOS);
        COPY(pw_dir, _PWF_DIR);
        COPY(pw_shell, _PWF_SHELL);
#undef COPY
#define COPY(field, flag) do {                  \
        if (template->pw_fields & flag)         \
                pwd->field = template->field;   \
} while (0)
        COPY(pw_uid, _PWF_UID);
        COPY(pw_gid, _PWF_GID);
#undef COPY
        free(copy);
        return (0);
}


static int
compat_exclude(const char *name, DB **db)
{
        DBT     key, data;

        if (*db == NULL &&
            (*db = dbopen(NULL, O_RDWR, 600, DB_HASH, 0)) == NULL)
                return (errno);
        key.size = strlen(name);
        key.data = (char *)name;
        data.size = 0;
        data.data = NULL;

        if ((*db)->put(*db, &key, &data, 0) == -1)
                return (errno);
        return (0);
}


static int
compat_is_excluded(const char *name, DB *db)
{
        DBT     key, data;

        if (db == NULL)
                return (0);
        key.size = strlen(name);
        key.data = (char *)name;
        return (db->get(db, &key, &data, 0) == 0);
}


static int
compat_redispatch(struct compat_state *st, enum nss_lookup_type how,
    enum nss_lookup_type lookup_how, const char *name, const char *lookup_name,
    uid_t uid, struct passwd *pwd, char *buffer, size_t bufsize, int *errnop)
{
        static const ns_src compatsrc[] = {
#ifdef YP
                { NSSRC_NIS, NS_SUCCESS },
#endif
                { NULL, 0 }
        };
        ns_dtab dtab[] = {
#ifdef YP
                { NSSRC_NIS, nis_passwd, NULL },
#endif
#ifdef HESIOD
                { NSSRC_DNS, dns_passwd, NULL },
#endif
                { NULL, NULL, NULL }
        };
        void            *discard;
        int              e, i, rv;

        for (i = 0; i < (int)(nitems(dtab) - 1); i++)
                dtab[i].mdata = (void *)lookup_how;
more:
        pwd_init(pwd);
        switch (lookup_how) {
        case nss_lt_all:
                rv = _nsdispatch(&discard, dtab, NSDB_PASSWD_COMPAT,
                    "getpwent_r", compatsrc, pwd, buffer, bufsize,
                    errnop);
                break;
        case nss_lt_id:
                rv = _nsdispatch(&discard, dtab, NSDB_PASSWD_COMPAT,
                    "getpwuid_r", compatsrc, uid, pwd, buffer,
                    bufsize, errnop);
                break;
        case nss_lt_name:
                rv = _nsdispatch(&discard, dtab, NSDB_PASSWD_COMPAT,
                    "getpwnam_r", compatsrc, lookup_name, pwd, buffer,
                    bufsize, errnop);
                break;
        default:
                return (NS_UNAVAIL);
        }
        if (rv != NS_SUCCESS)
                return (rv);
        if (compat_is_excluded(pwd->pw_name, st->exclude)) {
                if (how == nss_lt_all)
                        goto more;
                return (NS_NOTFOUND);
        }
        e = compat_use_template(pwd, &st->template, buffer, bufsize);
        if (e != 0) {
                *errnop = e;
                if (e == ERANGE)
                        return (NS_RETURN);
                else
                        return (NS_UNAVAIL);
        }
        switch (how) {
        case nss_lt_name:
                if (strcmp(name, pwd->pw_name) != 0)
                        return (NS_NOTFOUND);
                break;
        case nss_lt_id:
                if (uid != pwd->pw_uid)
                        return (NS_NOTFOUND);
                break;
        default:
                break;
        }
        return (NS_SUCCESS);
}


static void
compat_endstate(void *p)
{
        struct compat_state *st;

        if (p == NULL)
                return;
        st = (struct compat_state *)p;
        if (st->db != NULL)
                st->db->close(st->db);
        if (st->exclude != NULL)
                st->exclude->close(st->exclude);
        compat_clear_template(&st->template);
        free(p);
}


static int
compat_setpwent(void *retval, void *mdata, va_list ap)
{
        static const ns_src compatsrc[] = {
#ifdef YP
                { NSSRC_NIS, NS_SUCCESS },
#endif
                { NULL, 0 }
        };
        ns_dtab dtab[] = {
#ifdef YP
                { NSSRC_NIS, nis_setpwent, NULL },
#endif
#ifdef HESIOD
                { NSSRC_DNS, dns_setpwent, NULL },
#endif
                { NULL, NULL, NULL }
        };
        struct compat_state     *st;
        int                      rv, stayopen;

#define set_setent(x, y) do {                                   \
        int i;                                                  \
        for (i = 0; i < (int)(nitems(x) - 1); i++)              \
                x[i].mdata = (void *)y;                         \
} while (0)

        rv = compat_getstate(&st);
        if (rv != 0)
                return (NS_UNAVAIL);
        switch ((enum constants)mdata) {
        case SETPWENT:
                stayopen = va_arg(ap, int);
                st->keynum = 0;
                if (stayopen)
                        st->db = pwdbopen(&st->version);
                st->stayopen = stayopen;
                set_setent(dtab, mdata);
                (void)_nsdispatch(NULL, dtab, NSDB_PASSWD_COMPAT, "setpwent",
                    compatsrc, 0);
                break;
        case ENDPWENT:
                if (st->db != NULL) {
                        (void)st->db->close(st->db);
                        st->db = NULL;
                }
                set_setent(dtab, mdata);
                (void)_nsdispatch(NULL, dtab, NSDB_PASSWD_COMPAT, "endpwent",
                    compatsrc, 0);
                break;
        default:
                break;
        }
        return (NS_UNAVAIL);
#undef set_setent
}


static int
compat_passwd(void *retval, void *mdata, va_list ap)
{
        char                     keybuf[MAXLOGNAME + 1];
        DBT                      key, entry;
        struct compat_state     *st;
        enum nss_lookup_type     how;
        const char              *name;
        struct passwd           *pwd;
        char                    *buffer, *pw_name;
        char                    *host, *user, *domain;
        size_t                   bufsize;
        uid_t                    uid;
        uint32_t                 store;
        int                      rv, from_compat, stayopen, *errnop;

        from_compat = 0;
        name = NULL;
        uid = (uid_t)-1;
        how = (enum nss_lookup_type)mdata;
        switch (how) {
        case nss_lt_name:
                name = va_arg(ap, const char *);
                break;
        case nss_lt_id:
                uid = va_arg(ap, uid_t);
                break;
        case nss_lt_all:
                break;
        default:
                rv = NS_NOTFOUND;
                goto fin;
        }
        pwd = va_arg(ap, struct passwd *);
        buffer = va_arg(ap, char *);
        bufsize = va_arg(ap, size_t);
        errnop = va_arg(ap, int *);
        *errnop = compat_getstate(&st);
        if (*errnop != 0)
                return (NS_UNAVAIL);
        if (how == nss_lt_all && st->keynum < 0) {
                rv = NS_NOTFOUND;
                goto fin;
        }
        if (st->db == NULL &&
            (st->db = pwdbopen(&st->version)) == NULL) {
                *errnop = errno;
                rv = NS_UNAVAIL;
                goto fin;
        }
        if (how == nss_lt_all) {
                if (st->keynum < 0) {
                        rv = NS_NOTFOUND;
                        goto fin;
                }
                stayopen = 1;
        } else {
                st->keynum = 0;
                stayopen = st->stayopen;
        }
docompat:
        rv = NS_NOTFOUND;
        switch (st->compat) {
        case COMPAT_MODE_ALL:
                rv = compat_redispatch(st, how, how, name, name, uid, pwd,
                    buffer, bufsize, errnop);
                if (rv != NS_SUCCESS)
                        st->compat = COMPAT_MODE_OFF;
                break;
        case COMPAT_MODE_NETGROUP:
                /* XXX getnetgrent is not thread-safe. */
                do {
                        rv = getnetgrent(&host, &user, &domain);
                        if (rv == 0) {
                                endnetgrent();
                                st->compat = COMPAT_MODE_OFF;
                                rv = NS_NOTFOUND;
                                continue;
                        } else if (user == NULL || user[0] == '\0')
                                continue;
                        rv = compat_redispatch(st, how, nss_lt_name, name,
                            user, uid, pwd, buffer, bufsize, errnop);
                } while (st->compat == COMPAT_MODE_NETGROUP &&
                    !(rv & NS_TERMINATE));
                break;
        case COMPAT_MODE_NAME:
                rv = compat_redispatch(st, how, nss_lt_name, name, st->name,
                    uid, pwd, buffer, bufsize, errnop);
                free(st->name);
                st->name = NULL;
                st->compat = COMPAT_MODE_OFF;
                break;
        default:
                break;
        }
        if (rv & NS_TERMINATE) {
                from_compat = 1;
                goto fin;
        }
        key.data = keybuf;
        rv = NS_NOTFOUND;
        while (st->keynum >= 0) {
                st->keynum++;
                if (st->version < _PWD_CURRENT_VERSION) {
                        memcpy(&keybuf[1], &st->keynum, sizeof(st->keynum));
                        key.size = sizeof(st->keynum) + 1;
                } else {
                        store = htonl(st->keynum);
                        memcpy(&keybuf[1], &store, sizeof(store));
                        key.size = sizeof(store) + 1;
                }
                keybuf[0] = _PW_VERSIONED(_PW_KEYBYNUM, st->version);
                rv = st->db->get(st->db, &key, &entry, 0);
                if (rv < 0 || rv > 1) { /* should never return > 1 */
                        *errnop = errno;
                        rv = NS_UNAVAIL;
                        goto fin;
                } else if (rv == 1) {
                        st->keynum = -1;
                        rv = NS_NOTFOUND;
                        goto fin;
                }
                pw_name = (char *)entry.data;
                switch (pw_name[0]) {
                case '+':
                        switch (pw_name[1]) {
                        case '\0':
                                st->compat = COMPAT_MODE_ALL;
                                break;
                        case '@':
                                setnetgrent(&pw_name[2]);
                                st->compat = COMPAT_MODE_NETGROUP;
                                break;
                        default:
                                st->name = strdup(&pw_name[1]);
                                if (st->name == NULL) {
                                        syslog(LOG_ERR,
                                         "getpwent memory allocation failure");
                                        *errnop = ENOMEM;
                                        rv = NS_UNAVAIL;
                                        break;
                                }
                                st->compat = COMPAT_MODE_NAME;
                        }
                        if (entry.size > bufsize) {
                                *errnop = ERANGE;
                                rv = NS_RETURN;
                                goto fin;
                        }
                        memcpy(buffer, entry.data, entry.size);
                        rv = pwdb_versions[st->version].parse(buffer,
                            entry.size, pwd, errnop);
                        if (rv != NS_SUCCESS)
                                ;
                        else if (compat_set_template(pwd, &st->template) < 0) {
                                *errnop = ENOMEM;
                                rv = NS_UNAVAIL;
                                goto fin;
                        }
                        goto docompat;
                case '-':
                        switch (pw_name[1]) {
                        case '\0':
                                /* XXX Maybe syslog warning */
                                continue;
                        case '@':
                                setnetgrent(&pw_name[2]);
                                while (getnetgrent(&host, &user, &domain) !=
                                    0) {
                                        if (user != NULL && user[0] != '\0')
                                                compat_exclude(user,
                                                    &st->exclude);
                                }
                                endnetgrent();
                                continue;
                        default:
                                compat_exclude(&pw_name[1], &st->exclude);
                                continue;
                        }
                        break;
                default:
                        break;
                }
                if (compat_is_excluded((char *)entry.data, st->exclude))
                        continue;
                rv = pwdb_versions[st->version].match(entry.data, entry.size,
                    how, name, uid);
                if (rv == NS_RETURN)
                        break;
                else if (rv != NS_SUCCESS)
                        continue;
                if (entry.size > bufsize) {
                        *errnop = ERANGE;
                        rv = NS_RETURN;
                        break;
                }
                memcpy(buffer, entry.data, entry.size);
                rv = pwdb_versions[st->version].parse(buffer, entry.size, pwd,
                    errnop);
                if (rv & NS_TERMINATE)
                        break;
        }
fin:
        if (st->db != NULL && !stayopen) {
                (void)st->db->close(st->db);
                st->db = NULL;
        }
        if (rv == NS_SUCCESS) {
                if (!from_compat) {
                        pwd->pw_fields &= ~_PWF_SOURCE;
                        pwd->pw_fields |= _PWF_FILES;
                }
                if (retval != NULL)
                        *(struct passwd **)retval = pwd;
        }
        return (rv);
}


/*
 * common passwd line matching and parsing
 */
int
__pw_match_entry(const char *entry, size_t entrysize, enum nss_lookup_type how,
    const char *name, uid_t uid)
{
        const char      *p, *eom;
        char            *q;
        size_t           len;
        unsigned long    m;

        eom = entry + entrysize;
        for (p = entry; p < eom; p++)
                if (*p == ':')
                        break;
        if (*p != ':')
                return (NS_NOTFOUND);
        if (how == nss_lt_all)
                return (NS_SUCCESS);
        if (how == nss_lt_name) {
                len = strlen(name);
                if (len == (p - entry) && memcmp(name, entry, len) == 0)
                        return (NS_SUCCESS);
                else
                        return (NS_NOTFOUND);
        }
        for (p++; p < eom; p++)
                if (*p == ':')
                        break;
        if (*p != ':')
                return (NS_NOTFOUND);
        m = strtoul(++p, &q, 10);
        if (q[0] != ':' || (uid_t)m != uid)
                return (NS_NOTFOUND);
        else
                return (NS_SUCCESS);
}


/* XXX buffer must be NUL-terminated.  errnop is not set correctly. */
int
__pw_parse_entry(char *buffer, size_t bufsize __unused, struct passwd *pwd,
    int master, int *errnop __unused)
{

        if (__pw_scan(buffer, pwd, master ? _PWSCAN_MASTER : 0) == 0)
                return (NS_NOTFOUND);
        else
                return (NS_SUCCESS);
}