source: vendor/current/libcli/smb/smb2_create_blob.c

/*
   Unix SMB/CIFS implementation.

   SMB2 Create Context Blob handling

   Copyright (C) Andrew Tridgell 2005
   Copyright (C) Stefan Metzmacher 2008-2009

   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/smb/smb_common.h"

static size_t smb2_create_blob_padding(uint32_t offset, size_t n)
{
        if ((offset & (n-1)) == 0) return 0;
        return n - (offset & (n-1));
}

/*
  parse a set of SMB2 create blobs
*/
NTSTATUS smb2_create_blob_parse(TALLOC_CTX *mem_ctx, const DATA_BLOB buffer,
                                struct smb2_create_blobs *blobs)
{
        const uint8_t *data = buffer.data;
        uint32_t remaining = buffer.length;

        while (remaining > 0) {
                uint32_t next;
                uint32_t name_offset, name_length;
                uint32_t data_offset;
                uint32_t data_length;
                char *tag;
                DATA_BLOB b;
                NTSTATUS status;

                if (remaining < 16) {
                        return NT_STATUS_INVALID_PARAMETER;
                }
                next        = IVAL(data, 0);
                name_offset = SVAL(data, 4);
                name_length = SVAL(data, 6);
#if 0
                reserved    = SVAL(data, 8);
#endif
                data_offset = SVAL(data, 10);
                data_length = IVAL(data, 12);

                if ((next & 0x7) != 0 ||
                    next > remaining ||
                    name_offset != 16 ||
                    name_length < 4 ||
                    name_offset + name_length > remaining ||
                    (data_offset & 0x7) != 0 ||
                    (data_offset && (data_offset < name_offset + name_length)) ||
                    (data_offset > remaining) ||
                    (data_offset + (uint64_t)data_length > remaining)) {
                        return NT_STATUS_INVALID_PARAMETER;
                }

                tag = talloc_strndup(mem_ctx, (const char *)data + name_offset, name_length);
                if (tag == NULL) {
                        return NT_STATUS_NO_MEMORY;
                }

                b = data_blob_const(data+data_offset, data_length);
                status = smb2_create_blob_add(mem_ctx, blobs, tag, b);
                if (!NT_STATUS_IS_OK(status)) {
                        return status;
                }

                talloc_free(tag);

                if (next == 0) break;

                remaining -= next;
                data += next;

                if (remaining < 16) {
                        return NT_STATUS_INVALID_PARAMETER;
                }
        }

        return NT_STATUS_OK;
}


/*
  add a blob to a smb2_create attribute blob
*/
static NTSTATUS smb2_create_blob_push_one(TALLOC_CTX *mem_ctx, DATA_BLOB *buffer,
                                          const struct smb2_create_blob *blob,
                                          bool last)
{
        uint32_t ofs = buffer->length;
        size_t tag_length = strlen(blob->tag);
        size_t blob_offset = 0;
        size_t blob_pad = 0;
        size_t next_offset = 0;
        size_t next_pad = 0;
        bool ok;

        blob_offset = 0x10 + tag_length;
        blob_pad = smb2_create_blob_padding(blob_offset, 8);
        next_offset = blob_offset + blob_pad + blob->data.length;
        if (!last) {
                next_pad = smb2_create_blob_padding(next_offset, 8);
        }

        ok = data_blob_realloc(mem_ctx, buffer,
                               buffer->length + next_offset + next_pad);
        if (!ok) {
                return NT_STATUS_NO_MEMORY;
        }

        if (last) {
                SIVAL(buffer->data, ofs+0x00, 0);
        } else {
                SIVAL(buffer->data, ofs+0x00, next_offset + next_pad);
        }
        SSVAL(buffer->data, ofs+0x04, 0x10); /* offset of tag */
        SIVAL(buffer->data, ofs+0x06, tag_length); /* tag length */
        SSVAL(buffer->data, ofs+0x0A, blob_offset + blob_pad); /* offset of data */
        SIVAL(buffer->data, ofs+0x0C, blob->data.length);
        memcpy(buffer->data+ofs+0x10, blob->tag, tag_length);
        if (blob_pad > 0) {
                memset(buffer->data+ofs+blob_offset, 0, blob_pad);
                blob_offset += blob_pad;
        }
        memcpy(buffer->data+ofs+blob_offset, blob->data.data, blob->data.length);
        if (next_pad > 0) {
                memset(buffer->data+ofs+next_offset, 0, next_pad);
                next_offset += next_pad;
        }

        return NT_STATUS_OK;
}


/*
  create a buffer of a set of create blobs
*/
NTSTATUS smb2_create_blob_push(TALLOC_CTX *mem_ctx, DATA_BLOB *buffer,
                               const struct smb2_create_blobs blobs)
{
        int i;
        NTSTATUS status;

        *buffer = data_blob(NULL, 0);
        for (i=0; i < blobs.num_blobs; i++) {
                bool last = false;
                const struct smb2_create_blob *c;

                if ((i + 1) == blobs.num_blobs) {
                        last = true;
                }

                c = &blobs.blobs[i];
                status = smb2_create_blob_push_one(mem_ctx, buffer, c, last);
                if (!NT_STATUS_IS_OK(status)) {
                        return status;
                }
        }
        return NT_STATUS_OK;
}


NTSTATUS smb2_create_blob_add(TALLOC_CTX *mem_ctx, struct smb2_create_blobs *b,
                              const char *tag, DATA_BLOB data)
{
        struct smb2_create_blob *array;

        array = talloc_realloc(mem_ctx, b->blobs,
                               struct smb2_create_blob,
                               b->num_blobs + 1);
        NT_STATUS_HAVE_NO_MEMORY(array);
        b->blobs = array;

        b->blobs[b->num_blobs].tag = talloc_strdup(b->blobs, tag);
        NT_STATUS_HAVE_NO_MEMORY(b->blobs[b->num_blobs].tag);

        if (data.data) {
                b->blobs[b->num_blobs].data = data_blob_talloc(b->blobs,
                                                               data.data,
                                                               data.length);
                NT_STATUS_HAVE_NO_MEMORY(b->blobs[b->num_blobs].data.data);
        } else {
                b->blobs[b->num_blobs].data = data_blob_null;
        }

        b->num_blobs += 1;

        return NT_STATUS_OK;
}

/*
 * return the first blob with the given tag
 */
struct smb2_create_blob *smb2_create_blob_find(const struct smb2_create_blobs *b,
                                               const char *tag)
{
        uint32_t i;

        for (i=0; i < b->num_blobs; i++) {
                if (strcmp(b->blobs[i].tag, tag) == 0) {
                        return &b->blobs[i];
                }
        }

        return NULL;
}