/*
 * 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
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright (c) 2007, 2010, Oracle and/or its affiliates. All rights reserved.
 * Copyright 2013 Nexenta Systems, Inc.  All rights reserved.
 */

#include <sys/param.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <pwd.h>
#include <nss_dbdefs.h>
#include <assert.h>
#include <strings.h>
#include <sys/stat.h>
#include <sys/idmap.h>
#include <smbsrv/libsmb.h>
#include <smbsrv/libmlsvc.h>
#include <smbsrv/smbinfo.h>

#define SMB_AUTOHOME_KEYSIZ     128
#define SMB_AUTOHOME_MAXARG     4
#define SMB_AUTOHOME_BUFSIZ     2048

typedef struct smb_autohome_info {
        struct smb_autohome_info *magic1;
        FILE *fp;
        smb_autohome_t autohome;
        char buf[SMB_AUTOHOME_BUFSIZ];
        char *argv[SMB_AUTOHOME_MAXARG];
        int lineno;
        struct smb_autohome_info *magic2;
} smb_autohome_info_t;

static smb_autohome_info_t smb_ai;

static smb_autohome_t *smb_autohome_make_entry(smb_autohome_info_t *);
static char *smb_autohome_keysub(const char *, char *, int);
static smb_autohome_info_t *smb_autohome_getinfo(void);
static smb_autohome_t *smb_autohome_lookup(const char *);
static void smb_autohome_setent(void);
static void smb_autohome_endent(void);
static smb_autohome_t *smb_autohome_getent(const char *);
static void smb_autohome_parse_options(smb_share_t *);
static int smb_autohome_add_private(const char *, uid_t, gid_t);

/*
 * Add an autohome share.  See smbautohome(5) for details.
 *
 * If share directory contains backslash path separators, they will
 * be converted to forward slash to support NT/DOS path style for
 * autohome shares.
 *
 * We need to serialize calls to smb_autohome_lookup because it
 * operates on the global smb_ai structure.
 */
void
smb_autohome_add(const smb_token_t *token)
{

        char            *username;
        struct passwd   pw;
        char            buf[NSS_LINELEN_PASSWD];
        uid_t           uid;
        gid_t           gid;

        if (token->tkn_flags & SMB_ATF_ANON)
                return;

        uid = token->tkn_user.i_id;
        gid = token->tkn_primary_grp.i_id;

        if (IDMAP_ID_IS_EPHEMERAL(uid)) {
                username = token->tkn_account_name;
                assert(username);
        } else {
                if (getpwuid_r(uid, &pw, buf, sizeof (buf)) == NULL) {
                        syslog(LOG_DEBUG, "unable to determine name for " \
                            "UID: %u\n", uid);
                        return;
                }
                username = pw.pw_name;
        }

        if (smb_autohome_add_private(username, uid, gid) != NERR_Success) {
                if (!smb_isstrlwr(username)) {
                        (void) smb_strlwr(username);
                        (void) smb_autohome_add_private(username, uid, gid);
                }
        }
}

/*
 * Remove an autohome share.
 */
void
smb_autohome_remove(const char *username)
{
        smb_share_t si;

        assert(username);

        if (smb_shr_get((char *)username, &si) == NERR_Success) {
                if (si.shr_flags & SMB_SHRF_AUTOHOME)
                        (void) smb_shr_remove((char *)username);
        }
}

/*
 * An autohome share is not created if a static share using the same name
 * already exists.  Autohome shares will be added for each login attempt.
 *
 * Calling smb_shr_get() may return the first argument in all lower case so
 * a copy is passed in instead.
 *
 * We need to serialize calls to smb_autohome_lookup because it
 * operates on the global smb_ai structure.
 */
static int
smb_autohome_add_private(const char *username, uid_t uid, gid_t gid)
{
        static mutex_t  autohome_mutex;
        smb_share_t     si;
        smb_autohome_t  *ai;
        char            shr_name[MAXNAMELEN];

        (void) strlcpy(shr_name, username, sizeof (shr_name));

        if (smb_shr_get(shr_name, &si) == NERR_Success) {
                if ((si.shr_flags & SMB_SHRF_AUTOHOME) == 0)
                        return (NERR_Success);

                (void) smb_shr_add(&si);
                return (NERR_Success);
        }

        (void) mutex_lock(&autohome_mutex);

        if ((ai = smb_autohome_lookup(username)) == NULL) {
                (void) mutex_unlock(&autohome_mutex);
                return (NERR_ItemNotFound);
        }

        bzero(&si, sizeof (smb_share_t));
        (void) strlcpy(si.shr_path, ai->ah_path, MAXPATHLEN);
        (void) strsubst(si.shr_path, '\\', '/');

        (void) strlcpy(si.shr_name, username, MAXNAMELEN);
        (void) strlcpy(si.shr_container, ai->ah_container, MAXPATHLEN);
        (void) strlcpy(si.shr_cmnt, "Autohome", SMB_SHARE_CMNT_MAX);
        smb_autohome_parse_options(&si);
        si.shr_flags |= SMB_SHRF_TRANS | SMB_SHRF_AUTOHOME;
        si.shr_uid = uid;
        si.shr_gid = gid;

        (void) mutex_unlock(&autohome_mutex);

        return (smb_shr_add(&si));
}

/*
 * Search the autohome database for the specified name. The name cannot
 * be an empty string or begin with * or +.
 * 1. Search the file for the specified name.
 * 2. Check for the wildcard rule and, if present, treat it as a match.
 * 3. Check for the nsswitch rule and, if present, lookup the name
 *    via the name services. Note that the nsswitch rule will never
 *    be applied if the wildcard rule is present.
 *
 * Returns a pointer to the entry on success or null on failure.
 */
static smb_autohome_t *
smb_autohome_lookup(const char *name)
{
        struct passwd *pw;
        smb_autohome_t *ah = NULL;

        if (name == NULL)
                return (NULL);

        if (*name == '\0' || *name == '*' || *name == '+')
                return (NULL);

        smb_autohome_setent();

        while ((ah = smb_autohome_getent(name)) != NULL) {
                if (strcasecmp(ah->ah_name, name) == 0)
                        break;
        }

        if (ah == NULL) {
                smb_autohome_setent();

                while ((ah = smb_autohome_getent(name)) != NULL) {
                        if (strcasecmp(ah->ah_name, "*") == 0) {
                                ah->ah_name = (char *)name;
                                break;
                        }
                }
        }

        if (ah == NULL) {
                smb_autohome_setent();

                while ((ah = smb_autohome_getent("+nsswitch")) != NULL) {
                        if (strcasecmp("+nsswitch", ah->ah_name) != 0)
                                continue;
                        if ((pw = getpwnam(name)) == NULL) {
                                ah = NULL;
                                break;
                        }

                        ah->ah_name = pw->pw_name;

                        if (ah->ah_path)
                                ah->ah_container = ah->ah_path;

                        ah->ah_path = pw->pw_dir;
                        break;
                }
        }

        smb_autohome_endent();
        return (ah);
}

/*
 * Open or rewind the autohome database.
 */
static void
smb_autohome_setent(void)
{
        smb_autohome_info_t *si;
        char path[MAXNAMELEN];
        char filename[MAXNAMELEN];
        int rc;

        if ((si = smb_autohome_getinfo()) != 0) {
                (void) fseek(si->fp, 0L, SEEK_SET);
                si->lineno = 0;
                return;
        }

        if ((si = &smb_ai) == 0)
                return;

        rc = smb_config_getstr(SMB_CI_AUTOHOME_MAP, path, sizeof (path));
        if (rc != SMBD_SMF_OK)
                return;

        (void) snprintf(filename, MAXNAMELEN, "%s/%s", path,
            SMB_AUTOHOME_FILE);

        if ((si->fp = fopen(filename, "r")) == NULL)
                return;

        si->magic1 = si;
        si->magic2 = si;
        si->lineno = 0;
}

/*
 * Close the autohome database and invalidate the autohome info.
 * We can't zero the whole info structure because the application
 * should still have access to the data after the file is closed.
 */
static void
smb_autohome_endent(void)
{
        smb_autohome_info_t *si;

        if ((si = smb_autohome_getinfo()) != 0) {
                (void) fclose(si->fp);
                si->fp = 0;
                si->magic1 = 0;
                si->magic2 = 0;
        }
}

/*
 * Return the next entry in the autohome database, opening the file
 * if necessary.  Returns null on EOF or error.
 *
 * Note that we are not looking for the specified name. The name is
 * only used for key substitution, so that the caller sees the entry
 * in expanded form.
 */
static smb_autohome_t *
smb_autohome_getent(const char *name)
{
        smb_autohome_info_t *si;
        char *bp;

        if ((si = smb_autohome_getinfo()) == 0) {
                smb_autohome_setent();

                if ((si = smb_autohome_getinfo()) == 0)
                        return (0);
        }

        /*
         * Find the next non-comment, non-empty line.
         * Anything after a # is a comment and can be discarded.
         * Discard a newline to avoid it being included in the parsing
         * that follows.
         * Leading and training whitespace is discarded, and replicated
         * whitespace is compressed to simplify the token parsing,
         * although strsep() deals with that better than strtok().
         */
        do {
                if (fgets(si->buf, SMB_AUTOHOME_BUFSIZ, si->fp) == 0)
                        return (0);

                ++si->lineno;

                if ((bp = strpbrk(si->buf, "#\r\n")) != 0)
                        *bp = '\0';

                (void) trim_whitespace(si->buf);
                bp = strcanon(si->buf, " \t");
        } while (*bp == '\0');

        (void) smb_autohome_keysub(name, si->buf, SMB_AUTOHOME_BUFSIZ);
        return (smb_autohome_make_entry(si));
}

/*
 * Set up an autohome entry from the line buffer. The line should just
 * contain tokens separated by single whitespace. The line format is:
 *      <username> <home-dir-path> <ADS container>
 */
static smb_autohome_t *
smb_autohome_make_entry(smb_autohome_info_t *si)
{
        char *bp;
        int i;

        bp = si->buf;

        for (i = 0; i < SMB_AUTOHOME_MAXARG; ++i)
                si->argv[i] = NULL;

        for (i = 0; i < SMB_AUTOHOME_MAXARG; ++i) {
                do {
                        if ((si->argv[i] = strsep(&bp, " \t")) == NULL)
                                break;
                } while (*(si->argv[i]) == '\0');

                if (si->argv[i] == NULL)
                        break;
        }

        if ((si->autohome.ah_name = si->argv[0]) == NULL) {
                /*
                 * Sanity check: the name could be an empty
                 * string but it can't be a null pointer.
                 */
                return (0);
        }

        if ((si->autohome.ah_path = si->argv[1]) == NULL)
                si->autohome.ah_path = "";

        if ((si->autohome.ah_container = si->argv[2]) == NULL)
                si->autohome.ah_container = "";

        return (&si->autohome);
}

/*
 * Substitute the ? and & map keys.
 * ? is replaced by the first character of the name
 * & is replaced by the whole name.
 */
static char *
smb_autohome_keysub(const char *name, char *buf, int buflen)
{
        char key[SMB_AUTOHOME_KEYSIZ];
        char *ampersand;
        char *tmp;
        int bufsize = buflen;

        (void) strlcpy(key, buf, SMB_AUTOHOME_KEYSIZ);

        if ((tmp = strpbrk(key, " \t")) == NULL)
                return (NULL);

        *tmp = '\0';

        /*
         * Substitution characters are not allowed in the key.
         */
        if (strpbrk(key, "?&") != NULL)
                return (NULL);

        if (strcmp(key, "*") == 0 && name != NULL)
                (void) strlcpy(key, name, SMB_AUTOHOME_KEYSIZ);

        (void) strsubst(buf, '?', *key);

        while ((ampersand = strchr(buf, '&')) != NULL) {
                if ((tmp = strdup(ampersand + 1)) == NULL)
                        return (0);

                bufsize = buflen - (ampersand - buf);
                (void) strlcpy(ampersand, key, bufsize);
                (void) strlcat(ampersand, tmp, bufsize);
                free(tmp);
        }

        return (buf);
}

/*
 * Get a pointer to the context buffer and validate it.
 */
static smb_autohome_info_t *
smb_autohome_getinfo(void)
{
        smb_autohome_info_t *si;

        if ((si = &smb_ai) == 0)
                return (0);

        if ((si->magic1 == si) && (si->magic2 == si) && (si->fp != NULL))
                return (si);

        return (0);
}

/*
 * Parse the options string, which contains a comma separated list of
 * name-value pairs.  One of the options may be an AD container, which
 * is also a comma separated list of name-value pairs.  For example,
 * dn=ad,dn=sun,dn=com,ou=users
 *
 * All options other than the AD container will be extracted from
 * shr_container and used to set share properties.
 * On return, shr_container will contain the AD container string.
 */
static void
smb_autohome_parse_options(smb_share_t *si)
{
        char buf[MAXPATHLEN];
        char **argv;
        char **ap;
        char *bp;
        char *value;
        boolean_t separator = B_FALSE;
        int argc;
        int i;

        if (strlcpy(buf, si->shr_container, MAXPATHLEN) == 0)
                return;

        for (argc = 1, bp = si->shr_container; *bp != '\0'; ++bp)
                if (*bp == ',')
                        ++argc;

        if ((argv = calloc(argc + 1, sizeof (char *))) == NULL)
                return;

        ap = argv;
        for (bp = buf, i = 0; i < argc; ++i) {
                do {
                        if ((value = strsep(&bp, ",")) == NULL)
                                break;
                } while (*value == '\0');

                if (value == NULL)
                        break;

                *ap++ = value;
        }
        *ap = NULL;

        si->shr_container[0] = '\0';
        bp = si->shr_container;

        for (ap = argv; *ap != NULL; ++ap) {
                value = *ap;

                if (strncasecmp(value, "catia=", 6) == 0) {
                        smb_shr_sa_setflag((value + 6), si, SMB_SHRF_CATIA);
                        continue;
                }

                if (strncasecmp(value, "csc=", 4) == 0) {
                        smb_shr_sa_csc_option((value + 4), si);
                        continue;
                }

                if (strncasecmp(value, "abe=", 4) == 0) {
                        smb_shr_sa_setflag((value + 4), si, SMB_SHRF_ABE);
                        continue;
                }

                if (strncasecmp(value, "description=", 12) == 0) {
                        (void) strlcpy(si->shr_cmnt, (value + 12),
                            SMB_SHARE_CMNT_MAX);
                        continue;
                }

                if (strncasecmp(value, "rw=", 3) == 0) {
                        (void) strlcpy(si->shr_access_rw, (value + 3),
                            sizeof (si->shr_access_rw));
                        continue;
                }

                if (strncasecmp(value, "ro=", 3) == 0) {
                        (void) strlcpy(si->shr_access_ro, (value + 3),
                            sizeof (si->shr_access_ro));
                        continue;
                }

                if (strncasecmp(value, "none=", 5) == 0) {
                        (void) strlcpy(si->shr_access_none, (value + 5),
                            sizeof (si->shr_access_none));
                        continue;
                }

                if (separator)
                        (void) strlcat(bp, ",", MAXPATHLEN);
                (void) strlcat(bp, value, MAXPATHLEN);
                separator = B_TRUE;
        }

        free(argv);
}