/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
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 */
/*
 *      getgrent.c
 *
 * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 *
 * lib/nsswitch/compat/getgrent.c -- name-service-switch backend for getgrnam()
 *   et al that does 4.x compatibility.  It looks in /etc/group; if it finds
 *   group entries there that begin with "+" or "-", it consults other
 *   services.  By default it uses NIS (YP), but the user can override this
 *   with a "group_compat" entry in /etc/nsswitch.conf, e.g.
 *                      group_compat: ldap
 *
 * This code tries to produce the same results as the 4.x code, even when
 *   the latter seems ill thought-out.  Bug-compatible, in other words.
 *   Though we do try to be more reasonable about the format of "+" and "-"
 *   entries here, i.e. you don't have to pad them with spurious colons and
 *   bogus uid/gid values.
 *
 * Caveats:
 *    - More than one source may be specified, with the usual switch semantics,
 *      but having multiple sources here is definitely odd.
 *    - People who recursively specify "compat" deserve what they get.
 */

#include <grp.h>
#include <stdlib.h>
#include <unistd.h>             /* for GF_PATH */
#include <strings.h>
#include "compat_common.h"

static DEFINE_NSS_DB_ROOT(db_root);

static void
_nss_initf_group_compat(p)
        nss_db_params_t *p;
{
        p->name           = NSS_DBNAM_GROUP;
        p->config_name    = NSS_DBNAM_GROUP_COMPAT;
        p->default_config = NSS_DEFCONF_GROUP_COMPAT;
}

/*
 * Validates group entry replacing gid > MAXUID by GID_NOBODY.
 */
int
validate_group_ids(char *line, int *linelenp, int buflen, int extra_chars)
{
        char    *linep, *limit, *gidp;
        ulong_t gid;
        int     oldgidlen, idlen;
        int     linelen = *linelenp, newlinelen;

        if (linelen == 0 || *line == '+' || *line == '-')
                return (NSS_STR_PARSE_SUCCESS);

        linep = line;
        limit = line + linelen;

        while (linep < limit && *linep++ != ':') /* skip groupname */
                continue;
        while (linep < limit && *linep++ != ':') /* skip password */
                continue;
        if (linep == limit)
                return (NSS_STR_PARSE_PARSE);

        gidp = linep;
        gid = strtoul(gidp, (char **)&linep, 10); /* grab gid */
        oldgidlen = linep - gidp;
        if (linep >= limit || oldgidlen == 0)
                return (NSS_STR_PARSE_PARSE);

        if (gid <= MAXUID)
                return (NSS_STR_PARSE_SUCCESS);

        idlen = snprintf(NULL, 0, "%u", GID_NOBODY);
        newlinelen = linelen + idlen - oldgidlen;
        if (newlinelen + extra_chars > buflen)
                return (NSS_STR_PARSE_ERANGE);

        (void) bcopy(linep, gidp + idlen, limit - linep + extra_chars);
        (void) snprintf(gidp, idlen + 1, "%u", GID_NOBODY);
        *(gidp + idlen) = ':';
        *linelenp = newlinelen;
        return (NSS_STR_PARSE_SUCCESS);
}

static const char *
get_grname(argp)
        nss_XbyY_args_t         *argp;
{
        struct group            *g = (struct group *)argp->returnval;

        return (g->gr_name);
}

static int
check_grname(argp)
        nss_XbyY_args_t         *argp;
{
        struct group            *g = (struct group *)argp->returnval;

        return (strcmp(g->gr_name, argp->key.name) == 0);
}

static nss_status_t
getbyname(be, a)
        compat_backend_ptr_t    be;
        void                    *a;
{
        nss_XbyY_args_t         *argp = (nss_XbyY_args_t *)a;

        return (_nss_compat_XY_all(be, argp, check_grname,
                                NSS_DBOP_GROUP_BYNAME));
}

static int
check_grgid(argp)
        nss_XbyY_args_t         *argp;
{
        struct group            *g = (struct group *)argp->returnval;

        return (g->gr_gid == argp->key.gid);
}

static nss_status_t
getbygid(be, a)
        compat_backend_ptr_t    be;
        void                    *a;
{
        nss_XbyY_args_t         *argp = (nss_XbyY_args_t *)a;

        if (argp->key.gid > MAXUID)
                return (NSS_NOTFOUND);
        return (_nss_compat_XY_all(be, argp, check_grgid,
                                NSS_DBOP_GROUP_BYGID));
}

static nss_status_t
getbymember(be, a)
        compat_backend_ptr_t    be;
        void                    *a;
{
        struct nss_groupsbymem  *argp = (struct nss_groupsbymem *)a;
        int                     numgids = argp->numgids;
        int                     maxgids = argp->maxgids;
        gid_t                   *gid_array = argp->gid_array;
        struct nss_XbyY_args    grargs;
        struct group            *g;
        nss_XbyY_buf_t  *gb = NULL, *b = NULL;

        /*
         * Generic implementation:  enumerate using getent(), then check each
         *   group returned by getent() to see whether it contains the user.
         *   There are much faster ways, but at least this one gets the right
         *   answer.
         */
        if (numgids >= maxgids) {
                /* full gid_array;  nobody should have bothered to call us */
                return (NSS_SUCCESS);
        }

        b = NSS_XbyY_ALLOC(&gb, sizeof (struct group), NSS_BUFLEN_GROUP);
        if (b == 0)
                return (NSS_UNAVAIL);

        NSS_XbyY_INIT(&grargs, gb->result, gb->buffer, gb->buflen,
                argp->str2ent);
        g = (struct group *)gb->result;

        (void) _nss_compat_setent(be, 0);
        while (_nss_compat_getent(be, &grargs) == NSS_SUCCESS) {
                char            **mem;

                if (grargs.returnval == 0) {
                        continue;
                }
                for (mem = g->gr_mem;  *mem != 0;  mem++) {
                        if (strcmp(*mem, argp->username) == 0) {
                                int     gid = g->gr_gid;
                                int     i;
                                for (i = 0;  i < numgids;  i++) {
                                        if (gid == gid_array[i]) {
                                                break;
                                        }
                                }
                                if (i == numgids) {
                                        gid_array[numgids++] = gid;
                                        argp->numgids = numgids;
                                        if (numgids >= maxgids) {
                                                /* filled the gid_array */
                                                (void) _nss_compat_endent(be,
                                                                0);
                                                NSS_XbyY_FREE(&gb);
                                                return (NSS_SUCCESS);
                                        }
                                        /* Done with this group, try next */
                                        break;
                                }
                        }
                }
        }
        (void) _nss_compat_endent(be, 0);
        NSS_XbyY_FREE(&gb);
        return (NSS_NOTFOUND);  /* Really means "gid_array not full yet" */
}

/*ARGSUSED*/
static int
merge_grents(be, argp, fields)
        compat_backend_ptr_t    be;
        nss_XbyY_args_t         *argp;
        const char              **fields;
{
        struct group            *g      = (struct group *)argp->buf.result;
        char                    *buf;
        char                    *s;
        int                     parsestat;
        int                     dlen;

        /*
         * We're allowed to override the passwd (has anyone ever actually used
         *   the passwd in a group entry?) and the membership list, but not
         *   the groupname or the gid.
         * That's what the SunOS 4.x code did;  who are we to question it...
         *
         * Efficiency is heartlessly abandoned in the quest for simplicity.
         */
        if (fields[1] == 0 && fields[3] == 0 &&
                        be->return_string_data != 1) {
                /* No legal overrides, leave *argp unscathed */
                return (NSS_STR_PARSE_SUCCESS);
        }
        if ((buf = malloc(NSS_LINELEN_GROUP)) == 0) {
                return (NSS_STR_PARSE_PARSE);
                /* Really "out of memory", but PARSE_PARSE will have to do */
        }
        s = buf;
        (void) snprintf(s, NSS_LINELEN_GROUP, "%s:%s:%u:",
                g->gr_name,
                fields[1] != 0 ? fields[1] : g->gr_passwd,
                g->gr_gid);
        s += strlen(s);
        if (fields[3] != 0) {
                (void) strcpy(s, fields[3]);
                s += strlen(s);
        } else {
                char    **memp;

                for (memp = g->gr_mem;  *memp != 0;  memp++) {
                        size_t  len = strlen(*memp);
                        if (s + len + 1 <= buf + NSS_LINELEN_GROUP) {
                                if (memp != g->gr_mem) {
                                        *s++ = ',';
                                }
                                (void) memcpy(s, *memp, len);
                                s += len;
                        } else {
                                free(buf);
                                return (NSS_STR_PARSE_ERANGE);
                        }
                }
        }

        dlen = s - buf;

        /*
         * if asked, return the data in /etc file format
         */
        if (be->return_string_data == 1) {
                /* reset the result ptr to the original value */
                argp->buf.result = NULL;

                if (dlen > argp->buf.buflen) {
                        parsestat = NSS_STR_PARSE_ERANGE;
                } else {
                        (void) strncpy(argp->buf.buffer, buf, dlen);
                        argp->returnval = argp->buf.buffer;
                        argp->returnlen = dlen;
                        parsestat = NSS_SUCCESS;
                }
        } else {
                parsestat = (*argp->str2ent)(buf, dlen,
                                    argp->buf.result,
                                    argp->buf.buffer,
                                    argp->buf.buflen);
        }

        free(buf);
        return (parsestat);
}

static compat_backend_op_t group_ops[] = {
        _nss_compat_destr,
        _nss_compat_endent,
        _nss_compat_setent,
        _nss_compat_getent,
        getbyname,
        getbygid,
        getbymember
};

/*ARGSUSED*/
nss_backend_t *
_nss_compat_group_constr(dummy1, dummy2, dummy3)
        const char      *dummy1, *dummy2, *dummy3;
{
        return (_nss_compat_constr(group_ops,
                                sizeof (group_ops) / sizeof (group_ops[0]),
                                GF_PATH,
                                NSS_LINELEN_GROUP,
                                &db_root,
                                _nss_initf_group_compat,
                                0,
                                get_grname,
                                merge_grents));
}