/*
 * 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 2018 Nexenta Systems, Inc.  All rights reserved.
 */

#include <smbsrv/smb_kproto.h>
#include <smbsrv/smb_fsops.h>

/*
 * The maximum number of bytes to return from SMB Core
 * SmbRead or SmbLockAndRead.
 */
#define SMB_CORE_READ_MAX       4432

/*
 * The limit in bytes for SmbReadX.
 */
#define SMB_READX_MAX           0x10000

int smb_common_read(smb_request_t *, smb_rw_param_t *);

/*
 * Read bytes from a file or named pipe (SMB Core).
 *
 * The requested count specifies the number of bytes desired.  Offset
 * is limited to 32 bits, so this client request is inappropriate for
 * files with 64 bit offsets.
 *
 * On return, count is the number of bytes actually being returned, which
 * may be less than the count requested only if a read specifies bytes
 * beyond the current file size.  In this case only the bytes that exist
 * are returned.  A read completely beyond the end of file results in a
 * response of length zero.  This is the only circumstance when a zero
 * length response is generated.  A count returned which is less than the
 * count requested is the end of file indicator.
 */
smb_sdrc_t
smb_pre_read(smb_request_t *sr)
{
        smb_rw_param_t *param;
        uint32_t off_low;
        uint16_t count;
        uint16_t remcnt;
        int rc;

        param = kmem_zalloc(sizeof (smb_rw_param_t), KM_SLEEP);
        sr->arg.rw = param;

        rc = smbsr_decode_vwv(sr, "wwlw", &sr->smb_fid,
            &count, &off_low, &remcnt);

        param->rw_offset = (uint64_t)off_low;
        param->rw_count = (uint32_t)count;
        param->rw_mincnt = 0;

        DTRACE_SMB_START(op__Read, smb_request_t *, sr); /* arg.rw */

        return ((rc == 0) ? SDRC_SUCCESS : SDRC_ERROR);
}

void
smb_post_read(smb_request_t *sr)
{
        DTRACE_SMB_DONE(op__Read, smb_request_t *, sr); /* arg.rw */

        kmem_free(sr->arg.rw, sizeof (smb_rw_param_t));
}

smb_sdrc_t
smb_com_read(smb_request_t *sr)
{
        smb_rw_param_t *param = sr->arg.rw;
        uint16_t count;
        int rc;

        smbsr_lookup_file(sr);
        if (sr->fid_ofile == NULL) {
                smbsr_error(sr, NT_STATUS_INVALID_HANDLE, ERRDOS, ERRbadfid);
                return (SDRC_ERROR);
        }

        sr->user_cr = smb_ofile_getcred(sr->fid_ofile);

        if (param->rw_count > SMB_CORE_READ_MAX)
                param->rw_count = SMB_CORE_READ_MAX;

        if ((rc = smb_common_read(sr, param)) != 0) {
                smbsr_errno(sr, rc);
                return (SDRC_ERROR);
        }

        count = (uint16_t)param->rw_count;
        rc = smbsr_encode_result(sr, 5, VAR_BCC, "bw8.wbwC",
            5, count, VAR_BCC, 0x01, count, &sr->raw_data);

        return ((rc == 0) ? SDRC_SUCCESS : SDRC_ERROR);
}

/*
 * Lock and read bytes from a file (SMB Core Plus).  The SmbLockAndRead/
 * SmbLockAndWrite sub-dialect is only valid on disk files: reject any
 * attempt to use it on non-disk shares.
 *
 * The requested count specifies the number of bytes desired.  Offset
 * specifies the offset in the file of the first byte to be locked then
 * read. Note that offset is limited to 32 bits, so this client request
 * is inappropriate for files with 64 bit offsets.
 *
 * As with SMB_LOCK_BYTE_RANGE request, if the lock cannot be granted
 * immediately an error should be returned to the client.  If an error
 * occurs on the lock, the bytes should not be read.
 *
 * On return, count is the number of bytes actually being returned, which
 * may be less than the count requested only if a read specifies bytes
 * beyond the current file size.  In this case only the bytes that exist
 * are returned.  A read completely beyond the end of file results in a
 * response of length zero.  This is the only circumstance when a zero
 * length response is generated.  A count returned which is less than the
 * count requested is the end of file indicator.
 */
smb_sdrc_t
smb_pre_lock_and_read(smb_request_t *sr)
{
        smb_rw_param_t *param;
        uint32_t off_low;
        uint16_t count;
        uint16_t remcnt;
        int rc;

        param = kmem_zalloc(sizeof (smb_rw_param_t), KM_SLEEP);
        sr->arg.rw = param;

        rc = smbsr_decode_vwv(sr, "wwlw", &sr->smb_fid,
            &count, &off_low, &remcnt);

        param->rw_offset = (uint64_t)off_low;
        param->rw_count = (uint32_t)count;
        param->rw_mincnt = 0;

        DTRACE_SMB_START(op__LockAndRead, smb_request_t *, sr); /* arg.rw */

        return ((rc == 0) ? SDRC_SUCCESS : SDRC_ERROR);
}

void
smb_post_lock_and_read(smb_request_t *sr)
{
        DTRACE_SMB_DONE(op__LockAndRead, smb_request_t *, sr); /* arg.rw */

        kmem_free(sr->arg.rw, sizeof (smb_rw_param_t));
}

smb_sdrc_t
smb_com_lock_and_read(smb_request_t *sr)
{
        smb_rw_param_t *param = sr->arg.rw;
        DWORD status;
        uint32_t lk_pid;
        uint16_t count;
        int rc;

        if (STYPE_ISDSK(sr->tid_tree->t_res_type) == 0) {
                smbsr_error(sr, NT_STATUS_ACCESS_DENIED, ERRDOS, ERRnoaccess);
                return (SDRC_ERROR);
        }

        smbsr_lookup_file(sr);
        if (sr->fid_ofile == NULL) {
                smbsr_error(sr, NT_STATUS_INVALID_HANDLE, ERRDOS, ERRbadfid);
                return (SDRC_ERROR);
        }

        sr->user_cr = smb_ofile_getcred(sr->fid_ofile);

        /* Note: SMB1 locking uses 16-bit PIDs. */
        lk_pid = sr->smb_pid & 0xFFFF;

        status = smb_lock_range(sr, param->rw_offset, (uint64_t)param->rw_count,
            lk_pid, SMB_LOCK_TYPE_READWRITE, 0);

        if (status != NT_STATUS_SUCCESS) {
                smb_lock_range_error(sr, status);
                return (SDRC_ERROR);
        }

        if (param->rw_count > SMB_CORE_READ_MAX)
                param->rw_count = SMB_CORE_READ_MAX;

        if ((rc = smb_common_read(sr, param)) != 0) {
                smbsr_errno(sr, rc);
                return (SDRC_ERROR);
        }

        count = (uint16_t)param->rw_count;
        rc = smbsr_encode_result(sr, 5, VAR_BCC, "bw8.wbwC",
            5, count, VAR_BCC, 0x1, count, &sr->raw_data);

        return ((rc == 0) ? SDRC_SUCCESS : SDRC_ERROR);
}

/*
 * The SMB_COM_READ_RAW protocol was a negotiated option introduced in
 * SMB Core Plus to maximize performance when reading a large block
 * of data from a server.  It's obsolete and no longer supported.
 *
 * We keep a handler for it so the dtrace provider can see if
 * the client tried to use this command.
 */
smb_sdrc_t
smb_pre_read_raw(smb_request_t *sr)
{
        DTRACE_SMB_START(op__ReadRaw, smb_request_t *, sr);
        return (SDRC_SUCCESS);
}

void
smb_post_read_raw(smb_request_t *sr)
{
        DTRACE_SMB_DONE(op__ReadRaw, smb_request_t *, sr);
}

smb_sdrc_t
smb_com_read_raw(smb_request_t *sr)
{
        smbsr_error(sr, NT_STATUS_NOT_SUPPORTED, ERRDOS,
            ERROR_NOT_SUPPORTED);
        return (SDRC_ERROR);
}

/*
 * Read bytes from a file (SMB Core).  This request was extended in
 * LM 0.12 to support 64-bit offsets, indicated by sending a wct of
 * 12 and including additional offset information.
 *
 * MS-SMB 3.3.5.7 update to LM 0.12 4.2.4:
 * If wct is 12 and CAP_LARGE_READX is set, the count may be larger
 * than the negotiated buffer size.  If maxcnt_high is 0xFF, it must
 * be ignored.  Otherwise, maxcnt_high represents the upper 16 bits
 * of rw_count.
 */
smb_sdrc_t
smb_pre_read_andx(smb_request_t *sr)
{
        smb_rw_param_t *param;
        uint32_t off_low;
        uint32_t off_high;
        uint32_t maxcnt_high;
        uint16_t maxcnt_low;
        uint16_t mincnt;
        uint16_t remcnt;
        int rc;

        param = kmem_zalloc(sizeof (smb_rw_param_t), KM_SLEEP);
        sr->arg.rw = param;

        if (sr->smb_wct == 12) {
                rc = smbsr_decode_vwv(sr, "b3.wlwwlwl", &param->rw_andx,
                    &sr->smb_fid, &off_low, &maxcnt_low, &mincnt, &maxcnt_high,
                    &remcnt, &off_high);

                param->rw_offset = ((uint64_t)off_high << 32) |
                    (uint64_t)off_low;

                param->rw_count = (uint32_t)maxcnt_low;

                if ((sr->session->capabilities & CAP_LARGE_READX) &&
                    (maxcnt_high < 0xFF))
                        param->rw_count |= maxcnt_high << 16;
        } else {
                rc = smbsr_decode_vwv(sr, "b3.wlwwlw", &param->rw_andx,
                    &sr->smb_fid, &off_low, &maxcnt_low, &mincnt, &maxcnt_high,
                    &remcnt);

                param->rw_offset = (uint64_t)off_low;
                param->rw_count = (uint32_t)maxcnt_low;
        }

        param->rw_mincnt = 0;

        DTRACE_SMB_START(op__ReadX, smb_request_t *, sr); /* arg.rw */

        return ((rc == 0) ? SDRC_SUCCESS : SDRC_ERROR);
}

void
smb_post_read_andx(smb_request_t *sr)
{
        DTRACE_SMB_DONE(op__ReadX, smb_request_t *, sr); /* arg.rw */

        kmem_free(sr->arg.rw, sizeof (smb_rw_param_t));
}

smb_sdrc_t
smb_com_read_andx(smb_request_t *sr)
{
        smb_rw_param_t *param = sr->arg.rw;
        uint16_t datalen_high;
        uint16_t datalen_low;
        uint16_t data_offset;
        uint16_t offset2;
        int rc;

        smbsr_lookup_file(sr);
        if (sr->fid_ofile == NULL) {
                smbsr_error(sr, NT_STATUS_INVALID_HANDLE, ERRDOS, ERRbadfid);
                return (SDRC_ERROR);
        }

        sr->user_cr = smb_ofile_getcred(sr->fid_ofile);

        if (param->rw_count >= SMB_READX_MAX)
                param->rw_count = 0;

        if ((rc = smb_common_read(sr, param)) != 0) {
                smbsr_errno(sr, rc);
                return (SDRC_ERROR);
        }

        datalen_low = param->rw_count & 0xFFFF;
        datalen_high = (param->rw_count >> 16) & 0xFF;

        /*
         * If this is a secondary command, the data offset
         * includes the previous wct + sizeof(wct).
         */
        data_offset = (sr->andx_prev_wct == 0) ? 0 : sr->andx_prev_wct + 1;

        if (STYPE_ISIPC(sr->tid_tree->t_res_type)) {
                data_offset += 60;
                offset2 = (param->rw_andx == 0xFF) ? 0 : param->rw_count + 60;

                rc = smbsr_encode_result(sr, 12, VAR_BCC, "bb1.ww4.www8.wbC",
                    12,                 /* wct */
                    param->rw_andx,     /* secondary andx command */
                    offset2,            /* offset to next command */
                    0,                  /* set to 0 for named pipes */
                    datalen_low,        /* data byte count */
                    data_offset,        /* offset from start to data */
                    datalen_high,       /* data byte count */
                    VAR_BCC,            /* BCC marker */
                    0x00,               /* padding */
                    &sr->raw_data);
        } else {
                data_offset += 59;
                offset2 = (param->rw_andx == 0xFF) ? 0 : param->rw_count + 59;

                rc = smbsr_encode_result(sr, 12, VAR_BCC, "bb1.ww4.www8.wC",
                    12,                 /* wct */
                    param->rw_andx,     /* secondary andx command */
                    offset2,            /* offset to next command */
                    -1,                 /* must be -1 for regular files */
                    datalen_low,        /* data byte count */
                    data_offset,        /* offset from start to data */
                    datalen_high,       /* data byte count */
                    VAR_BCC,            /* BCC marker */
                    &sr->raw_data);
        }

        return ((rc == 0) ? SDRC_SUCCESS : SDRC_ERROR);
}

/*
 * Common function for reading files or IPC/MSRPC named pipes.  All
 * protocol read functions should lookup the fid before calling this
 * function.  We can't move the fid lookup here because lock-and-read
 * requires the fid to do locking before attempting the read.
 *
 * Reading from a file does not break oplocks because any need for
 * breaking before read is handled in open.
 *
 * Returns errno values.
 */
int
smb_common_read(smb_request_t *sr, smb_rw_param_t *param)
{
        smb_ofile_t *ofile = sr->fid_ofile;
        smb_node_t *node;
        smb_vdb_t *vdb = &param->rw_vdb;
        struct mbuf *top;
        int rc;

        vdb->vdb_tag = 0;
        vdb->vdb_uio.uio_iov = &vdb->vdb_iovec[0];
        vdb->vdb_uio.uio_iovcnt = MAX_IOVEC;
        vdb->vdb_uio.uio_resid = param->rw_count;
        vdb->vdb_uio.uio_loffset = (offset_t)param->rw_offset;
        vdb->vdb_uio.uio_segflg = UIO_SYSSPACE;
        vdb->vdb_uio.uio_extflg = UIO_COPY_DEFAULT;

        switch (sr->tid_tree->t_res_type & STYPE_MASK) {
        case STYPE_DISKTREE:
                node = ofile->f_node;

                if (!smb_node_is_dir(node)) {
                        rc = smb_lock_range_access(sr, node, param->rw_offset,
                            param->rw_count, B_FALSE);
                        if (rc != NT_STATUS_SUCCESS) {
                                rc = ERANGE;
                                break;
                        }
                }

                if ((ofile->f_flags & SMB_OFLAGS_EXECONLY) &&
                    !(sr->smb_flg2 & SMB_FLAGS2_READ_IF_EXECUTE)) {
                        /*
                         * SMB_FLAGS2_READ_IF_EXECUTE: permit execute-only
                         * reads.
                         *
                         * Reject request if the file has been opened
                         * execute-only and SMB_FLAGS2_READ_IF_EXECUTE is not
                         * set.
                         */
                        rc = EACCES;
                        break;
                }

                sr->raw_data.max_bytes = vdb->vdb_uio.uio_resid;
                top = smb_mbuf_allocate(&vdb->vdb_uio);

                rc = smb_fsop_read(sr, sr->user_cr, node, ofile,
                    &vdb->vdb_uio, 0);

                sr->raw_data.max_bytes -= vdb->vdb_uio.uio_resid;
                smb_mbuf_trim(top, sr->raw_data.max_bytes);
                MBC_ATTACH_MBUF(&sr->raw_data, top);
                break;

        case STYPE_IPC:
                sr->raw_data.max_bytes = vdb->vdb_uio.uio_resid;
                top = smb_mbuf_allocate(&vdb->vdb_uio);

                rc = smb_opipe_read(sr, &vdb->vdb_uio);

                sr->raw_data.max_bytes -= vdb->vdb_uio.uio_resid;
                smb_mbuf_trim(top, sr->raw_data.max_bytes);
                MBC_ATTACH_MBUF(&sr->raw_data, top);
                break;

        default:
                rc = EACCES;
                break;
        }

        param->rw_count -= vdb->vdb_uio.uio_resid;

        if (rc != 0)
                return (rc);

        if (param->rw_mincnt != 0 && param->rw_count < param->rw_mincnt) {
                /*
                 * mincnt is only used by read-raw and is typically
                 * zero.  If mincnt is greater than zero and the
                 * number of bytes read is less than mincnt, tell
                 * the client that we read nothing.
                 */
                param->rw_count = 0;
        }

        param->rw_offset += param->rw_count;
        mutex_enter(&sr->fid_ofile->f_mutex);
        ofile->f_seek_pos = param->rw_offset;
        mutex_exit(&sr->fid_ofile->f_mutex);
        return (rc);
}