source: vendor/3.6.0/source4/libcli/smb2/request.c

/* 
   Unix SMB/CIFS implementation.

   SMB2 client request handling

   Copyright (C) Andrew Tridgell        2005
   Copyright (C) Stefan Metzmacher      2005
   
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.
   
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
   
   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#include "includes.h"
#include "libcli/raw/libcliraw.h"
#include "libcli/smb2/smb2.h"
#include "../lib/util/dlinklist.h"
#include "lib/events/events.h"
#include "libcli/smb2/smb2_calls.h"

/* fill in the bufinfo */
void smb2_setup_bufinfo(struct smb2_request *req)
{
        req->in.bufinfo.mem_ctx    = req;
        req->in.bufinfo.flags      = BUFINFO_FLAG_UNICODE | BUFINFO_FLAG_SMB2;
        req->in.bufinfo.align_base = req->in.buffer;
        if (req->in.dynamic) {
                req->in.bufinfo.data       = req->in.dynamic;
                req->in.bufinfo.data_size  = req->in.body_size - req->in.body_fixed;
        } else {
                req->in.bufinfo.data       = NULL;
                req->in.bufinfo.data_size  = 0;
        }
}


/* destroy a request structure */
static int smb2_request_destructor(struct smb2_request *req)
{
        if (req->transport) {
                /* remove it from the list of pending requests (a null op if
                   its not in the list) */
                DLIST_REMOVE(req->transport->pending_recv, req);
        }
        return 0;
}

/*
  initialise a smb2 request
*/
struct smb2_request *smb2_request_init(struct smb2_transport *transport, uint16_t opcode,
                                       uint16_t body_fixed_size, bool body_dynamic_present,
                                       uint32_t body_dynamic_size)
{
        struct smb2_request *req;
        uint64_t seqnum;
        uint32_t hdr_offset;
        uint32_t flags = 0;
        bool compound = false;

        if (body_dynamic_present) {
                if (body_dynamic_size == 0) {
                        body_dynamic_size = 1;
                }
        } else {
                body_dynamic_size = 0;
        }

        req = talloc(transport, struct smb2_request);
        if (req == NULL) return NULL;

        seqnum = transport->seqnum;
        if (transport->credits.charge > 0) {
                transport->seqnum += transport->credits.charge;
        } else {
                transport->seqnum += 1;
        }

        req->state     = SMB2_REQUEST_INIT;
        req->transport = transport;
        req->session   = NULL;
        req->tree      = NULL;
        req->seqnum    = seqnum;
        req->status    = NT_STATUS_OK;
        req->async.fn  = NULL;
        req->next = req->prev = NULL;

        ZERO_STRUCT(req->cancel);
        ZERO_STRUCT(req->in);

        if (transport->compound.missing > 0) {
                compound = true;
                transport->compound.missing -= 1;
                req->out = transport->compound.buffer;
                ZERO_STRUCT(transport->compound.buffer);
                if (transport->compound.related) {
                        flags |= SMB2_HDR_FLAG_CHAINED;
                }
        } else {
                ZERO_STRUCT(req->out);
        }

        if (req->out.size > 0) {
                hdr_offset = req->out.size;
        } else {
                hdr_offset = NBT_HDR_SIZE;
        }

        req->out.size      = hdr_offset + SMB2_HDR_BODY + body_fixed_size;
        req->out.allocated = req->out.size + body_dynamic_size;

        req->out.buffer = talloc_realloc(req, req->out.buffer,
                                         uint8_t, req->out.allocated);
        if (req->out.buffer == NULL) {
                talloc_free(req);
                return NULL;
        }

        req->out.hdr       = req->out.buffer + hdr_offset;
        req->out.body      = req->out.hdr + SMB2_HDR_BODY;
        req->out.body_fixed= body_fixed_size;
        req->out.body_size = body_fixed_size;
        req->out.dynamic   = (body_dynamic_size ? req->out.body + body_fixed_size : NULL);

        SIVAL(req->out.hdr, 0,                          SMB2_MAGIC);
        SSVAL(req->out.hdr, SMB2_HDR_LENGTH,            SMB2_HDR_BODY);
        SSVAL(req->out.hdr, SMB2_HDR_EPOCH,             transport->credits.charge);
        SIVAL(req->out.hdr, SMB2_HDR_STATUS,            0);
        SSVAL(req->out.hdr, SMB2_HDR_OPCODE,            opcode);
        SSVAL(req->out.hdr, SMB2_HDR_CREDIT,            transport->credits.ask_num);
        SIVAL(req->out.hdr, SMB2_HDR_FLAGS,             flags);
        SIVAL(req->out.hdr, SMB2_HDR_NEXT_COMMAND,      0);
        SBVAL(req->out.hdr, SMB2_HDR_MESSAGE_ID,        req->seqnum);
        SIVAL(req->out.hdr, SMB2_HDR_PID,               0);
        SIVAL(req->out.hdr, SMB2_HDR_TID,               0);
        SBVAL(req->out.hdr, SMB2_HDR_SESSION_ID,                0);
        memset(req->out.hdr+SMB2_HDR_SIGNATURE, 0, 16);

        /* set the length of the fixed body part and +1 if there's a dynamic part also */
        SSVAL(req->out.body, 0, body_fixed_size + (body_dynamic_size?1:0));

        /* 
         * if we have a dynamic part, make sure the first byte
         * which is always be part of the packet is initialized
         */
        if (body_dynamic_size && !compound) {
                req->out.size += 1;
                SCVAL(req->out.dynamic, 0, 0);
        }

        talloc_set_destructor(req, smb2_request_destructor);

        return req;
}

/*
    initialise a smb2 request for tree operations
*/
struct smb2_request *smb2_request_init_tree(struct smb2_tree *tree, uint16_t opcode,
                                            uint16_t body_fixed_size, bool body_dynamic_present,
                                            uint32_t body_dynamic_size)
{
        struct smb2_request *req = smb2_request_init(tree->session->transport, opcode, 
                                                     body_fixed_size, body_dynamic_present,
                                                     body_dynamic_size);
        if (req == NULL) return NULL;

        SBVAL(req->out.hdr,  SMB2_HDR_SESSION_ID, tree->session->uid);
        SIVAL(req->out.hdr,  SMB2_HDR_PID, tree->session->pid);
        SIVAL(req->out.hdr,  SMB2_HDR_TID, tree->tid);
        req->session = tree->session;
        req->tree = tree;

        return req;     
}

/* destroy a request structure and return final status */
NTSTATUS smb2_request_destroy(struct smb2_request *req)
{
        NTSTATUS status;

        /* this is the error code we give the application for when a
           _send() call fails completely */
        if (!req) return NT_STATUS_UNSUCCESSFUL;

        if (req->state == SMB2_REQUEST_ERROR &&
            NT_STATUS_IS_OK(req->status)) {
                status = NT_STATUS_INTERNAL_ERROR;
        } else {
                status = req->status;
        }

        talloc_free(req);
        return status;
}

/*
  receive a response to a packet
*/
bool smb2_request_receive(struct smb2_request *req)
{
        /* req can be NULL when a send has failed. This eliminates lots of NULL
           checks in each module */
        if (!req) return false;

        /* keep receiving packets until this one is replied to */
        while (req->state <= SMB2_REQUEST_RECV) {
                if (event_loop_once(req->transport->socket->event.ctx) != 0) {
                        return false;
                }
        }

        return req->state == SMB2_REQUEST_DONE;
}

/* Return true if the last packet was in error */
bool smb2_request_is_error(struct smb2_request *req)
{
        return NT_STATUS_IS_ERR(req->status);
}

/* Return true if the last packet was OK */
bool smb2_request_is_ok(struct smb2_request *req)
{
        return NT_STATUS_IS_OK(req->status);
}

/*
  check if a range in the reply body is out of bounds
*/
bool smb2_oob(struct smb2_request_buffer *buf, const uint8_t *ptr, size_t size)
{
        if (size == 0) {
                /* zero bytes is never out of range */
                return false;
        }
        /* be careful with wraparound! */
        if ((uintptr_t)ptr < (uintptr_t)buf->body ||
            (uintptr_t)ptr >= (uintptr_t)buf->body + buf->body_size ||
            size > buf->body_size ||
            (uintptr_t)ptr + size > (uintptr_t)buf->body + buf->body_size) {
                return true;
        }
        return false;
}

size_t smb2_padding_size(uint32_t offset, size_t n)
{
        if ((offset & (n-1)) == 0) return 0;
        return n - (offset & (n-1));
}

static size_t smb2_padding_fix(struct smb2_request_buffer *buf)
{
        if (buf->dynamic == (buf->body + buf->body_fixed)) {
                if (buf->dynamic != (buf->buffer + buf->size)) {
                        return 1;
                }
        }
        return 0;
}

/*
  grow a SMB2 buffer by the specified amount
*/
NTSTATUS smb2_grow_buffer(struct smb2_request_buffer *buf, size_t increase)
{
        size_t hdr_ofs;
        size_t dynamic_ofs;
        uint8_t *buffer_ptr;
        uint32_t newsize = buf->size + increase;

        /* a packet size should be limited a bit */
        if (newsize >= 0x00FFFFFF) return NT_STATUS_MARSHALL_OVERFLOW;

        if (newsize <= buf->allocated) return NT_STATUS_OK;

        hdr_ofs = buf->hdr - buf->buffer;
        dynamic_ofs = buf->dynamic - buf->buffer;

        buffer_ptr = talloc_realloc(buf, buf->buffer, uint8_t, newsize);
        NT_STATUS_HAVE_NO_MEMORY(buffer_ptr);

        buf->buffer     = buffer_ptr;
        buf->hdr        = buf->buffer + hdr_ofs;
        buf->body       = buf->hdr    + SMB2_HDR_BODY;
        buf->dynamic    = buf->buffer + dynamic_ofs;
        buf->allocated  = newsize;

        return NT_STATUS_OK;
}

/*
  pull a uint16_t ofs/ uint16_t length/blob triple from a data blob
  the ptr points to the start of the offset/length pair
*/
NTSTATUS smb2_pull_o16s16_blob(struct smb2_request_buffer *buf, TALLOC_CTX *mem_ctx, uint8_t *ptr, DATA_BLOB *blob)
{
        uint16_t ofs, size;
        if (smb2_oob(buf, ptr, 4)) {
                return NT_STATUS_INVALID_PARAMETER;
        }
        ofs  = SVAL(ptr, 0);
        size = SVAL(ptr, 2);
        if (ofs == 0) {
                *blob = data_blob(NULL, 0);
                return NT_STATUS_OK;
        }
        if (smb2_oob(buf, buf->hdr + ofs, size)) {
                return NT_STATUS_INVALID_PARAMETER;
        }
        *blob = data_blob_talloc(mem_ctx, buf->hdr + ofs, size);
        NT_STATUS_HAVE_NO_MEMORY(blob->data);
        return NT_STATUS_OK;
}

/*
  push a uint16_t ofs/ uint16_t length/blob triple into a data blob
  the ofs points to the start of the offset/length pair, and is relative
  to the body start
*/
NTSTATUS smb2_push_o16s16_blob(struct smb2_request_buffer *buf, 
                               uint16_t ofs, DATA_BLOB blob)
{
        NTSTATUS status;
        size_t offset;
        size_t padding_length;
        size_t padding_fix;
        uint8_t *ptr = buf->body+ofs;

        if (buf->dynamic == NULL) {
                return NT_STATUS_INVALID_PARAMETER;
        }

        /* we have only 16 bit for the size */
        if (blob.length > 0xFFFF) {
                return NT_STATUS_INVALID_PARAMETER;
        }

        /* check if there're enough room for ofs and size */
        if (smb2_oob(buf, ptr, 4)) {
                return NT_STATUS_INVALID_PARAMETER;
        }

        if (blob.data == NULL) {
                if (blob.length != 0) {
                        return NT_STATUS_INTERNAL_ERROR;
                }
                SSVAL(ptr, 0, 0);
                SSVAL(ptr, 2, 0);
                return NT_STATUS_OK;
        }

        offset = buf->dynamic - buf->hdr;
        padding_length = smb2_padding_size(offset, 2);
        offset += padding_length;
        padding_fix = smb2_padding_fix(buf);

        SSVAL(ptr, 0, offset);
        SSVAL(ptr, 2, blob.length);

        status = smb2_grow_buffer(buf, blob.length + padding_length - padding_fix);
        NT_STATUS_NOT_OK_RETURN(status);

        memset(buf->dynamic, 0, padding_length);
        buf->dynamic += padding_length;

        memcpy(buf->dynamic, blob.data, blob.length);
        buf->dynamic += blob.length;

        buf->size += blob.length + padding_length - padding_fix;
        buf->body_size += blob.length + padding_length;

        return NT_STATUS_OK;
}


/*
  push a uint16_t ofs/ uint32_t length/blob triple into a data blob
  the ofs points to the start of the offset/length pair, and is relative
  to the body start
*/
NTSTATUS smb2_push_o16s32_blob(struct smb2_request_buffer *buf, 
                               uint16_t ofs, DATA_BLOB blob)
{
        NTSTATUS status;
        size_t offset;
        size_t padding_length;
        size_t padding_fix;
        uint8_t *ptr = buf->body+ofs;

        if (buf->dynamic == NULL) {
                return NT_STATUS_INVALID_PARAMETER;
        }

        /* check if there're enough room for ofs and size */
        if (smb2_oob(buf, ptr, 6)) {
                return NT_STATUS_INVALID_PARAMETER;
        }

        if (blob.data == NULL) {
                if (blob.length != 0) {
                        return NT_STATUS_INTERNAL_ERROR;
                }
                SSVAL(ptr, 0, 0);
                SIVAL(ptr, 2, 0);
                return NT_STATUS_OK;
        }

        offset = buf->dynamic - buf->hdr;
        padding_length = smb2_padding_size(offset, 2);
        offset += padding_length;
        padding_fix = smb2_padding_fix(buf);

        SSVAL(ptr, 0, offset);
        SIVAL(ptr, 2, blob.length);

        status = smb2_grow_buffer(buf, blob.length + padding_length - padding_fix);
        NT_STATUS_NOT_OK_RETURN(status);

        memset(buf->dynamic, 0, padding_length);
        buf->dynamic += padding_length;

        memcpy(buf->dynamic, blob.data, blob.length);
        buf->dynamic += blob.length;

        buf->size += blob.length + padding_length - padding_fix;
        buf->body_size += blob.length + padding_length;

        return NT_STATUS_OK;
}


/*
  push a uint32_t ofs/ uint32_t length/blob triple into a data blob
  the ofs points to the start of the offset/length pair, and is relative
  to the body start
*/
NTSTATUS smb2_push_o32s32_blob(struct smb2_request_buffer *buf, 
                               uint32_t ofs, DATA_BLOB blob)
{
        NTSTATUS status;
        size_t offset;
        size_t padding_length;
        size_t padding_fix;
        uint8_t *ptr = buf->body+ofs;

        if (buf->dynamic == NULL) {
                return NT_STATUS_INVALID_PARAMETER;
        }

        /* check if there're enough room for ofs and size */
        if (smb2_oob(buf, ptr, 8)) {
                return NT_STATUS_INVALID_PARAMETER;
        }

        if (blob.data == NULL) {
                if (blob.length != 0) {
                        return NT_STATUS_INTERNAL_ERROR;
                }
                SIVAL(ptr, 0, 0);
                SIVAL(ptr, 4, 0);
                return NT_STATUS_OK;
        }

        offset = buf->dynamic - buf->hdr;
        padding_length = smb2_padding_size(offset, 8);
        offset += padding_length;
        padding_fix = smb2_padding_fix(buf);

        SIVAL(ptr, 0, offset);
        SIVAL(ptr, 4, blob.length);

        status = smb2_grow_buffer(buf, blob.length + padding_length - padding_fix);
        NT_STATUS_NOT_OK_RETURN(status);

        memset(buf->dynamic, 0, padding_length);
        buf->dynamic += padding_length;

        memcpy(buf->dynamic, blob.data, blob.length);
        buf->dynamic += blob.length;

        buf->size += blob.length + padding_length - padding_fix;
        buf->body_size += blob.length + padding_length;

        return NT_STATUS_OK;
}


/*
  push a uint32_t length/ uint32_t ofs/blob triple into a data blob
  the ofs points to the start of the length/offset pair, and is relative
  to the body start
*/
NTSTATUS smb2_push_s32o32_blob(struct smb2_request_buffer *buf, 
                               uint32_t ofs, DATA_BLOB blob)
{
        NTSTATUS status;
        size_t offset;
        size_t padding_length;
        size_t padding_fix;
        uint8_t *ptr = buf->body+ofs;

        if (buf->dynamic == NULL) {
                return NT_STATUS_INVALID_PARAMETER;
        }

        /* check if there're enough room for ofs and size */
        if (smb2_oob(buf, ptr, 8)) {
                return NT_STATUS_INVALID_PARAMETER;
        }

        if (blob.data == NULL) {
                if (blob.length != 0) {
                        return NT_STATUS_INTERNAL_ERROR;
                }
                SIVAL(ptr, 0, 0);
                SIVAL(ptr, 4, 0);
                return NT_STATUS_OK;
        }

        offset = buf->dynamic - buf->hdr;
        padding_length = smb2_padding_size(offset, 8);
        offset += padding_length;
        padding_fix = smb2_padding_fix(buf);

        SIVAL(ptr, 0, blob.length);
        SIVAL(ptr, 4, offset);

        status = smb2_grow_buffer(buf, blob.length + padding_length - padding_fix);
        NT_STATUS_NOT_OK_RETURN(status);

        memset(buf->dynamic, 0, padding_length);
        buf->dynamic += padding_length;

        memcpy(buf->dynamic, blob.data, blob.length);
        buf->dynamic += blob.length;

        buf->size += blob.length + padding_length - padding_fix;
        buf->body_size += blob.length + padding_length;

        return NT_STATUS_OK;
}

/*
  pull a uint16_t ofs/ uint32_t length/blob triple from a data blob
  the ptr points to the start of the offset/length pair
*/
NTSTATUS smb2_pull_o16s32_blob(struct smb2_request_buffer *buf, TALLOC_CTX *mem_ctx, uint8_t *ptr, DATA_BLOB *blob)
{
        uint16_t ofs;
        uint32_t size;

        if (smb2_oob(buf, ptr, 6)) {
                return NT_STATUS_INVALID_PARAMETER;
        }
        ofs  = SVAL(ptr, 0);
        size = IVAL(ptr, 2);
        if (ofs == 0) {
                *blob = data_blob(NULL, 0);
                return NT_STATUS_OK;
        }
        if (smb2_oob(buf, buf->hdr + ofs, size)) {
                return NT_STATUS_INVALID_PARAMETER;
        }
        *blob = data_blob_talloc(mem_ctx, buf->hdr + ofs, size);
        NT_STATUS_HAVE_NO_MEMORY(blob->data);
        return NT_STATUS_OK;
}

/*
  pull a uint32_t ofs/ uint32_t length/blob triple from a data blob
  the ptr points to the start of the offset/length pair
*/
NTSTATUS smb2_pull_o32s32_blob(struct smb2_request_buffer *buf, TALLOC_CTX *mem_ctx, uint8_t *ptr, DATA_BLOB *blob)
{
        uint32_t ofs, size;
        if (smb2_oob(buf, ptr, 8)) {
                return NT_STATUS_INVALID_PARAMETER;
        }
        ofs  = IVAL(ptr, 0);
        size = IVAL(ptr, 4);
        if (ofs == 0) {
                *blob = data_blob(NULL, 0);
                return NT_STATUS_OK;
        }
        if (smb2_oob(buf, buf->hdr + ofs, size)) {
                return NT_STATUS_INVALID_PARAMETER;
        }
        *blob = data_blob_talloc(mem_ctx, buf->hdr + ofs, size);
        NT_STATUS_HAVE_NO_MEMORY(blob->data);
        return NT_STATUS_OK;
}

/*
  pull a uint16_t ofs/ uint32_t length/blob triple from a data blob
  the ptr points to the start of the offset/length pair
  
  In this varient the uint16_t is padded by an extra 2 bytes, making
  the size aligned on 4 byte boundary
*/
NTSTATUS smb2_pull_o16As32_blob(struct smb2_request_buffer *buf, TALLOC_CTX *mem_ctx, uint8_t *ptr, DATA_BLOB *blob)
{
        uint32_t ofs, size;
        if (smb2_oob(buf, ptr, 8)) {
                return NT_STATUS_INVALID_PARAMETER;
        }
        ofs  = SVAL(ptr, 0);
        size = IVAL(ptr, 4);
        if (ofs == 0) {
                *blob = data_blob(NULL, 0);
                return NT_STATUS_OK;
        }
        if (smb2_oob(buf, buf->hdr + ofs, size)) {
                return NT_STATUS_INVALID_PARAMETER;
        }
        *blob = data_blob_talloc(mem_ctx, buf->hdr + ofs, size);
        NT_STATUS_HAVE_NO_MEMORY(blob->data);
        return NT_STATUS_OK;
}

/*
  pull a uint32_t length/ uint32_t ofs/blob triple from a data blob
  the ptr points to the start of the offset/length pair
*/
NTSTATUS smb2_pull_s32o32_blob(struct smb2_request_buffer *buf, TALLOC_CTX *mem_ctx, uint8_t *ptr, DATA_BLOB *blob)
{
        uint32_t ofs, size;
        if (smb2_oob(buf, ptr, 8)) {
                return NT_STATUS_INVALID_PARAMETER;
        }
        size = IVAL(ptr, 0);
        ofs  = IVAL(ptr, 4);
        if (ofs == 0) {
                *blob = data_blob(NULL, 0);
                return NT_STATUS_OK;
        }
        if (smb2_oob(buf, buf->hdr + ofs, size)) {
                return NT_STATUS_INVALID_PARAMETER;
        }
        *blob = data_blob_talloc(mem_ctx, buf->hdr + ofs, size);
        NT_STATUS_HAVE_NO_MEMORY(blob->data);
        return NT_STATUS_OK;
}

/*
  pull a uint32_t length/ uint16_t ofs/blob triple from a data blob
  the ptr points to the start of the offset/length pair
*/
NTSTATUS smb2_pull_s32o16_blob(struct smb2_request_buffer *buf, TALLOC_CTX *mem_ctx, uint8_t *ptr, DATA_BLOB *blob)
{
        uint32_t ofs, size;
        if (smb2_oob(buf, ptr, 8)) {
                return NT_STATUS_INVALID_PARAMETER;
        }
        size = IVAL(ptr, 0);
        ofs  = SVAL(ptr, 4);
        if (ofs == 0) {
                *blob = data_blob(NULL, 0);
                return NT_STATUS_OK;
        }
        if (smb2_oob(buf, buf->hdr + ofs, size)) {
                return NT_STATUS_INVALID_PARAMETER;
        }
        *blob = data_blob_talloc(mem_ctx, buf->hdr + ofs, size);
        NT_STATUS_HAVE_NO_MEMORY(blob->data);
        return NT_STATUS_OK;
}

/*
  pull a string in a uint16_t ofs/ uint16_t length/blob format
  UTF-16 without termination
*/
NTSTATUS smb2_pull_o16s16_string(struct smb2_request_buffer *buf, TALLOC_CTX *mem_ctx,
                                 uint8_t *ptr, const char **str)
{
        DATA_BLOB blob;
        NTSTATUS status;
        void *vstr;
        bool ret;

        status = smb2_pull_o16s16_blob(buf, mem_ctx, ptr, &blob);
        NT_STATUS_NOT_OK_RETURN(status);

        if (blob.data == NULL) {
                *str = NULL;
                return NT_STATUS_OK;
        }

        if (blob.length == 0) {
                char *s;
                s = talloc_strdup(mem_ctx, "");
                NT_STATUS_HAVE_NO_MEMORY(s);
                *str = s;
                return NT_STATUS_OK;
        }

        ret = convert_string_talloc(mem_ctx, CH_UTF16, CH_UNIX, 
                                     blob.data, blob.length, &vstr, NULL, false);
        data_blob_free(&blob);
        (*str) = (char *)vstr;
        if (!ret) {
                return NT_STATUS_ILLEGAL_CHARACTER;
        }
        return NT_STATUS_OK;
}

/*
  push a string in a uint16_t ofs/ uint16_t length/blob format
  UTF-16 without termination
*/
NTSTATUS smb2_push_o16s16_string(struct smb2_request_buffer *buf,
                                 uint16_t ofs, const char *str)
{
        DATA_BLOB blob;
        NTSTATUS status;
        bool ret;

        if (str == NULL) {
                return smb2_push_o16s16_blob(buf, ofs, data_blob(NULL, 0));
        }

        if (*str == 0) {
                blob.data = discard_const_p(uint8_t, str);
                blob.length = 0;
                return smb2_push_o16s16_blob(buf, ofs, blob);
        }

        ret = convert_string_talloc(buf->buffer, CH_UNIX, CH_UTF16, 
                                     str, strlen(str), (void **)&blob.data, &blob.length, 
                                         false);
        if (!ret) {
                return NT_STATUS_ILLEGAL_CHARACTER;
        }

        status = smb2_push_o16s16_blob(buf, ofs, blob);
        data_blob_free(&blob);
        return status;
}

/*
  push a file handle into a buffer
*/
void smb2_push_handle(uint8_t *data, struct smb2_handle *h)
{
        SBVAL(data, 0, h->data[0]);
        SBVAL(data, 8, h->data[1]);
}

/*
  pull a file handle from a buffer
*/
void smb2_pull_handle(uint8_t *ptr, struct smb2_handle *h)
{
        h->data[0] = BVAL(ptr, 0);
        h->data[1] = BVAL(ptr, 8);
}