/*
 * 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 2017 Nexenta Systems, Inc.  All rights reserved.
 */

#include <sys/types.h>
#include <sys/param.h>
#include <sys/sunddi.h>
#include <sys/errno.h>
#include <sys/extdirent.h>
#include <smbsrv/string.h>
#include <smbsrv/smb_vops.h>
#include <smbsrv/smb_kproto.h>
#include <smbsrv/smb_fsops.h>

/*
 * Characters we don't allow in DOS file names.
 * If a filename contains any of these chars, it should get mangled.
 *
 * '.' is also an invalid DOS char but since it's a special
 * case it doesn't appear in the list.
 */
static const char invalid_dos_chars[] =
        "\001\002\003\004\005\006\007\010\011\012\013\014\015\016\017"
        "\020\021\022\023\024\025\026\027\030\031\032\033\034\035\036\037"
        " \"/\\:|<>*?";

/*
 * According to MSKB article #142982, Windows deletes invalid chars and
 * spaces from file name in mangling process; and invalid chars include:
 * ."/\[]:;=,
 *
 * But some of these chars and some other chars (e.g. +) are replaced
 * with underscore (_). They are introduced here as special chars.
 */
static const char special_chars[] = "[];=,+";

#define isinvalid(c)    (strchr(invalid_dos_chars, c) || (c & 0x80))

static int smb_generate_mangle(uint64_t, char *, size_t);
static char smb_mangle_char(char);

/*
 * Return true if name contains characters that are invalid in a file
 * name or it is a reserved DOS device name.  Otherwise, returns false.
 *
 * Control characters (values 0 - 31) and the following characters are
 * invalid:
 *      < > : " / \ | ? *
 */
boolean_t
smb_is_invalid_filename(const char *name)
{
        const char *p;

        if ((p = strpbrk(name, invalid_dos_chars)) != NULL) {
                if (*p != ' ')
                        return (B_TRUE);
        }

        return (smb_is_reserved_dos_name(name));
}

/*
 * smb_is_reserved_dos_name
 *
 * This function checks if the name is a reserved DOS device name.
 * The device name should not be followed immediately by an extension,
 * for example, NUL.txt.
 */
boolean_t
smb_is_reserved_dos_name(const char *name)
{
        static char *cnames[] = { "CLOCK$", "COM1", "COM2", "COM3", "COM4",
                "COM5", "COM6", "COM7", "COM8", "COM9", "CON" };
        static char *lnames[] = { "LPT1", "LPT2", "LPT3", "LPT4", "LPT5",
                "LPT6", "LPT7", "LPT8", "LPT9" };
        static char *others[] = { "AUX", "NUL", "PRN" };
        char    **reserved;
        char    ch;
        int     n_reserved;
        int     len;
        int     i;

        ch = smb_toupper(*name);

        switch (ch) {
        case 'A':
        case 'N':
        case 'P':
                reserved = others;
                n_reserved = sizeof (others) / sizeof (others[0]);
                break;
        case 'C':
                reserved = cnames;
                n_reserved = sizeof (cnames) / sizeof (cnames[0]);
                break;
        case 'L':
                reserved = lnames;
                n_reserved = sizeof (lnames) / sizeof (lnames[0]);
                break;
        default:
                return (B_FALSE);
        }

        for (i  = 0; i < n_reserved; ++i) {
                len = strlen(reserved[i]);

                if (smb_strcasecmp(reserved[i], name, len) == 0) {
                        ch = *(name + len);
                        if ((ch == '\0') || (ch == '.'))
                                return (B_TRUE);
                }
        }

        return (B_FALSE);
}

/*
 * smb_needs_mangled
 *
 * A name needs to be mangled if any of the following are true:
 * - the first character is dot (.) and the name is not "." or ".."
 * - the name contains illegal or special charsacter
 * - the name name length > 12
 * - the number of dots == 0 and length > 8
 * - the number of dots > 1
 * - the number of dots == 1 and name is not 8.3
 */
boolean_t
smb_needs_mangled(const char *name)
{
        int len, extlen, ndots;
        const char *p;
        const char *last_dot;

        if ((strcmp(name, ".") == 0) || (strcmp(name, "..") == 0))
                return (B_FALSE);

        if (*name == '.')
                return (B_TRUE);

        len = 0;
        ndots = 0;
        last_dot = NULL;
        for (p = name; *p != '\0'; ++p) {
                if (smb_iscntrl(*p) ||
                    (strchr(special_chars, *p) != NULL) ||
                    (strchr(invalid_dos_chars, *p)) != NULL)
                        return (B_TRUE);

                if (*p == '.') {
                        ++ndots;
                        last_dot = p;
                }
                ++len;
        }

        if ((len > SMB_NAME83_LEN) ||
            (ndots == 0 && len > SMB_NAME83_BASELEN) ||
            (ndots > 1)) {
                return (B_TRUE);
        }

        if (last_dot != NULL) {
                extlen = strlen(last_dot + 1);
                if ((extlen == 0) || (extlen > SMB_NAME83_EXTLEN))
                        return (B_TRUE);

                if ((len - extlen - 1) > SMB_NAME83_BASELEN)
                        return (B_TRUE);
        }

        return (B_FALSE);
}

/*
 * smb_mangle_char
 *
 * If c is an invalid DOS character or non-ascii, it should
 * not be used in the mangled name. We return -1 to indicate
 * an invalid character.
 *
 * If c is a special chars, it should be replaced with '_'.
 *
 * Otherwise c is returned as uppercase.
 */
static char
smb_mangle_char(char c)
{
        if (isinvalid(c))
                return (-1);

        if (strchr(special_chars, c))
                return ('_');

        return (smb_toupper(c));
}

/*
 * smb_generate_mangle
 *
 * Generate a mangle string containing at least 2 characters and
 * at most (buflen - 1) characters.
 *
 * Returns the number of chars in the generated mangle.
 */
static int
smb_generate_mangle(uint64_t fid, char *buf, size_t buflen)
{
        static char *base36 = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
        char *p = buf;
        int i;

        if (fid == 0)
                fid = (uint64_t)-1;

        *p++ = '~';
        for (i = 2; (i < buflen) && (fid > 0); fid /= 36, ++i)
                *p++ = base36[fid % 36];
        *p = '\0';

        return (i - 1);
}

/*
 * smb_maybe_mangled
 *
 * Mangled names should be valid DOS file names: less than 12 characters
 * long, contain at least one tilde character and conform to an 8.3 name
 * format.
 *
 * Returns true if the name looks like a mangled name.
 */
boolean_t
smb_maybe_mangled(char *name)
{
        const char *p;
        boolean_t has_tilde = B_FALSE;
        int ndots = 0;
        int i;

        for (p = name, i = 0; (*p != '\0') && (i < SMB_NAME83_LEN); i++, p++) {
                if ((strchr(special_chars, *p) != NULL) ||
                    (strchr(invalid_dos_chars, *p) != NULL))
                        return (B_FALSE);

                if (*p == '.') {
                        if ((++ndots) > 1)
                                return (B_FALSE);
                }

                if ((*p == '~') && (i < SMB_NAME83_BASELEN))
                        has_tilde = B_TRUE;

                if (*p == '.' && !has_tilde)
                        return (B_FALSE);
        }

        return ((*p == '\0') && has_tilde);
}

/*
 * smb_mangle
 *
 * Microsoft knowledge base article #142982 describes how Windows
 * generates 8.3 filenames from long file names. Some other details
 * can be found in article #114816.
 *
 * This function will mangle the name whether mangling is required
 * or not. Callers should use smb_needs_mangled() to determine whether
 * mangling is required.
 *
 * name         original file name
 * fid          inode number to generate unique mangle
 * buf          output buffer (buflen bytes) to contain mangled name
 */
void
smb_mangle(const char *name, ino64_t fid, char *buf, size_t buflen)
{
        int i, avail;
        const char *p;
        char c;
        char *pbuf;
        char mangle_buf[SMB_NAME83_BASELEN];

        ASSERT(name && buf && (buflen >= SMB_SHORTNAMELEN));

        avail = SMB_NAME83_BASELEN -
            smb_generate_mangle(fid, mangle_buf, SMB_NAME83_BASELEN);
        name += strspn(name, ".");

        /*
         * Copy up to avail characters from the base part of name
         * to buf then append the generated mangle string.
         */
        p = name;
        pbuf = buf;
        for (i = 0; (i < avail) && (*p != '\0') && (*p != '.'); ++i, ++p) {
                if ((c = smb_mangle_char(*p)) == -1)
                        continue;
                *pbuf++ = c;
        }
        *pbuf = '\0';
        (void) strlcat(pbuf, mangle_buf, SMB_NAME83_BASELEN);
        pbuf = strchr(pbuf, '\0');

        /*
         * Find the last dot in the name. If there is a dot and an
         * extension, append '.' and up to SMB_NAME83_EXTLEN extension
         * characters to the mangled name.
         */
        if (((p = strrchr(name, '.')) != NULL) && (*(++p) != '\0')) {
                *pbuf++ = '.';
                for (i = 0; (i < SMB_NAME83_EXTLEN) && (*p != '\0'); ++i, ++p) {
                        if ((c = smb_mangle_char(*p)) == -1)
                                continue;
                        *pbuf++ = c;
                }
        }

        *pbuf = '\0';
}

/*
 * smb_unmangle
 *
 * Given a mangled name, try to find the real file name as it appears
 * in the directory entry.
 *
 * smb_unmangle should only be called on names for which
 * smb_maybe_mangled() is true
 *
 * The flags arg is no longer used, but retained just to avoid
 * changing the many callers of this function.
 *
 * Returns:
 *   0       - SUCCESS. Unmangled name is returned in namebuf.
 *   EINVAL  - a parameter was invalid.
 *   ENOTDIR - dnode is not a directory node.
 *   ENOENT  - an unmangled name could not be found.
 */
#define SMB_UNMANGLE_BUFSIZE    (4 * 1024)
int
smb_unmangle(smb_node_t *dnode, char *name, char *namebuf,
    int buflen, uint32_t flags)
{
        _NOTE(ARGUNUSED(flags)) // avoid changing all callers
        int             err, eof, bufsize;
        uint64_t        offset;
        ino64_t         ino;
        char            *namep, *buf;
        char            shortname[SMB_SHORTNAMELEN];
        vnode_t         *vp;
        char            *bufptr;
        dirent64_t      *dp;
        cred_t          *cr = zone_kcred();
        int             rc = ENOENT;

        if (dnode == NULL || name == NULL || namebuf == NULL || buflen == 0)
                return (EINVAL);

        ASSERT(smb_maybe_mangled(name) == B_TRUE);

        if (!smb_node_is_dir(dnode))
                return (ENOTDIR);

        vp = dnode->vp;
        *namebuf = '\0';

        buf = kmem_alloc(SMB_UNMANGLE_BUFSIZE, KM_SLEEP);
        bufptr = buf;
        bufsize = 0;
        offset = 0;     // next entry offset
        eof = B_FALSE;

        for (;;) {
                /*
                 * Read some entries, if buffer empty or
                 * we've scanned all of it.  Flags zero
                 * (no edirent, no ABE wanted here)
                 */
                if (bufsize <= 0) {
                        bufsize = SMB_UNMANGLE_BUFSIZE;
                        rc = smb_vop_readdir(vp, offset, buf,
                            &bufsize, &eof, 0, cr);
                        if (rc != 0)
                                break; /* error */
                        if (bufsize == 0) {
                                eof = B_TRUE;
                                rc = ENOENT;
                                break;
                        }
                        bufptr = buf;
                }
                /* LINTED pointer alignment */
                dp = (dirent64_t *)bufptr;

                /*
                 * Partial records are not supposed to happen,
                 * but let's be defensive. If this happens,
                 * restart at the current offset.
                 */
                bufptr += dp->d_reclen;
                bufsize -= dp->d_reclen;
                if (bufsize < 0)
                        continue;

                offset = dp->d_off;
                ino = dp->d_ino;
                namep = dp->d_name;

                /* skip non utf8 filename */
                if (u8_validate(namep, strlen(namep), NULL,
                    U8_VALIDATE_ENTIRE, &err) < 0)
                        continue;

                smb_mangle(namep, ino, shortname, SMB_SHORTNAMELEN);
                if (smb_strcasecmp(name, shortname, 0) == 0) {
                        (void) strlcpy(namebuf, namep, buflen);
                        rc = 0;
                        break;
                }
        }

        kmem_free(buf, SMB_UNMANGLE_BUFSIZE);
        return (rc);
}