librpc/ndr/ndr.c

説明を見る。

/* 
   Unix SMB/CIFS implementation.

   libndr interface

   Copyright (C) Andrew Tridgell 2003
   
   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 2 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, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

/*
  this provides the core routines for NDR parsing functions

  see http://www.opengroup.org/onlinepubs/9629399/chap14.htm for details
  of NDR encoding rules
*/

#include "includes.h"

#define NDR_BASE_MARSHALL_SIZE 1024

/* this guid indicates NDR encoding in a protocol tower */
const struct dcerpc_syntax_id ndr_transfer_syntax = {
  { 0x8a885d04, 0x1ceb, 0x11c9, {0x9f, 0xe8}, {0x08,0x00,0x2b,0x10,0x48,0x60} },
  2
};

const struct dcerpc_syntax_id ndr64_transfer_syntax = {
  { 0x71710533, 0xbeba, 0x4937, {0x83, 0x19}, {0xb5,0xdb,0xef,0x9c,0xcc,0x36} },
  1
};

/*
  work out the number of bytes needed to align on a n byte boundary
*/
size_t ndr_align_size(uint32_t offset, size_t n)
{
        if ((offset & (n-1)) == 0) return 0;
        return n - (offset & (n-1));
}

/*
  initialise a ndr parse structure from a data blob
*/
struct ndr_pull *ndr_pull_init_blob(const DATA_BLOB *blob, TALLOC_CTX *mem_ctx)
{
        struct ndr_pull *ndr;

        ndr = talloc_zero(mem_ctx, struct ndr_pull);
        if (!ndr) return NULL;
        ndr->current_mem_ctx = mem_ctx;

        ndr->data = blob->data;
        ndr->data_size = blob->length;

        return ndr;
}

/*
  advance by 'size' bytes
*/
NTSTATUS ndr_pull_advance(struct ndr_pull *ndr, uint32_t size)
{
        ndr->offset += size;
        if (ndr->offset > ndr->data_size) {
                return ndr_pull_error(ndr, NDR_ERR_BUFSIZE, 
                                      "ndr_pull_advance by %u failed",
                                      size);
        }
        return NT_STATUS_OK;
}

/*
  set the parse offset to 'ofs'
*/
static NTSTATUS ndr_pull_set_offset(struct ndr_pull *ndr, uint32_t ofs)
{
        ndr->offset = ofs;
        if (ndr->offset > ndr->data_size) {
                return ndr_pull_error(ndr, NDR_ERR_BUFSIZE, 
                                      "ndr_pull_set_offset %u failed",
                                      ofs);
        }
        return NT_STATUS_OK;
}

/* save the offset/size of the current ndr state */
void ndr_pull_save(struct ndr_pull *ndr, struct ndr_pull_save *save)
{
        save->offset = ndr->offset;
        save->data_size = ndr->data_size;
}

/* restore the size/offset of a ndr structure */
void ndr_pull_restore(struct ndr_pull *ndr, struct ndr_pull_save *save)
{
        ndr->offset = save->offset;
        ndr->data_size = save->data_size;
}


/* create a ndr_push structure, ready for some marshalling */
struct ndr_push *ndr_push_init_ctx(TALLOC_CTX *mem_ctx)
{
        struct ndr_push *ndr;

        ndr = talloc_zero(mem_ctx, struct ndr_push);
        if (!ndr) {
                return NULL;
        }

        ndr->flags = 0;
        ndr->alloc_size = NDR_BASE_MARSHALL_SIZE;
        ndr->data = talloc_array(ndr, uint8_t, ndr->alloc_size);
        if (!ndr->data) {
                return NULL;
        }

        return ndr;
}


/* create a ndr_push structure, ready for some marshalling */
struct ndr_push *ndr_push_init(void)
{
        return ndr_push_init_ctx(NULL);
}

/* free a ndr_push structure */
void ndr_push_free(struct ndr_push *ndr)
{
        talloc_free(ndr);
}


/* return a DATA_BLOB structure for the current ndr_push marshalled data */
DATA_BLOB ndr_push_blob(struct ndr_push *ndr)
{
        DATA_BLOB blob;
        blob.data = ndr->data;
        blob.length = ndr->offset;
        blob.free = NULL;
        if (ndr->alloc_size > ndr->offset) {
                ndr->data[ndr->offset] = 0;
        }
        return blob;
}


/*
  expand the available space in the buffer to ndr->offset + extra_size
*/
NTSTATUS ndr_push_expand(struct ndr_push *ndr, uint32_t extra_size)
{
        uint32_t size = extra_size + ndr->offset;

        if (size < ndr->offset) {
                /* extra_size overflowed the offset */
                return ndr_push_error(ndr, NDR_ERR_BUFSIZE, "Overflow in push_expand to %u",
                                        size);
        }

        if (ndr->alloc_size > size) {
                return NT_STATUS_OK;
        }

        ndr->alloc_size += NDR_BASE_MARSHALL_SIZE;
        if (size+1 > ndr->alloc_size) {
                ndr->alloc_size = size+1;
        }
        ndr->data = talloc_realloc(ndr, ndr->data, uint8_t, ndr->alloc_size);
        if (!ndr->data) {
                return ndr_push_error(ndr, NDR_ERR_ALLOC, "Failed to push_expand to %u",
                                      ndr->alloc_size);
        }

        return NT_STATUS_OK;
}

void ndr_print_debug_helper(struct ndr_print *ndr, const char *format, ...) _PRINTF_ATTRIBUTE(2,3)
{
        va_list ap;
        char *s = NULL;
        int i;

        va_start(ap, format);
        vasprintf(&s, format, ap);
        va_end(ap);

        for (i=0;i<ndr->depth;i++) {
                DEBUG(0,("    "));
        }

        DEBUG(0,("%s\n", s));
        free(s);
}

static void ndr_print_string_helper(struct ndr_print *ndr, const char *format, ...) _PRINTF_ATTRIBUTE(2,3)
{
        va_list ap;
        int i;

        for (i=0;i<ndr->depth;i++) {
                ndr->private_data = talloc_asprintf_append(
                        (char *)ndr->private_data, "    ");
        }

        va_start(ap, format);
        ndr->private_data = talloc_vasprintf_append(
                (char *)ndr->private_data, format, ap);
        va_end(ap);
        ndr->private_data = talloc_asprintf_append(
                (char *)ndr->private_data, "\n");
}

/*
  a useful helper function for printing idl structures via DEBUG()
*/
void ndr_print_debug(ndr_print_fn_t fn, const char *name, void *ptr)
{
        struct ndr_print *ndr;

        ndr = talloc_zero(NULL, struct ndr_print);
        if (!ndr) return;
        ndr->print = ndr_print_debug_helper;
        ndr->depth = 1;
        ndr->flags = 0;
        fn(ndr, name, ptr);
        talloc_free(ndr);
}

/*
  a useful helper function for printing idl unions via DEBUG()
*/
void ndr_print_union_debug(ndr_print_fn_t fn, const char *name, uint32_t level, void *ptr)
{
        struct ndr_print *ndr;

        ndr = talloc_zero(NULL, struct ndr_print);
        if (!ndr) return;
        ndr->print = ndr_print_debug_helper;
        ndr->depth = 1;
        ndr->flags = 0;
        ndr_print_set_switch_value(ndr, ptr, level);
        fn(ndr, name, ptr);
        talloc_free(ndr);
}

/*
  a useful helper function for printing idl function calls via DEBUG()
*/
void ndr_print_function_debug(ndr_print_function_t fn, const char *name, int flags, void *ptr)
{
        struct ndr_print *ndr;

        ndr = talloc_zero(NULL, struct ndr_print);
        if (!ndr) return;
        ndr->print = ndr_print_debug_helper;
        ndr->depth = 1;
        ndr->flags = 0;
        fn(ndr, name, flags, ptr);
        talloc_free(ndr);
}


/*
  a useful helper function for printing idl function calls to a string
*/
char *ndr_print_function_string(TALLOC_CTX *mem_ctx,
                                ndr_print_function_t fn, const char *name, 
                                int flags, void *ptr)
{
        struct ndr_print *ndr;
        char *ret = NULL;

        ndr = talloc_zero(mem_ctx, struct ndr_print);
        if (!ndr) return NULL;
        if (!(ndr->private_data = talloc_strdup(mem_ctx, ""))) {
                TALLOC_FREE(ndr);
                return NULL;
        }
        ndr->print = ndr_print_string_helper;
        ndr->depth = 1;
        ndr->flags = 0;
        fn(ndr, name, flags, ptr);
        ret = (char *)ndr->private_data;
        talloc_free(ndr);
        return ret;
}

void ndr_set_flags(uint32_t *pflags, uint32_t new_flags)
{
        /* the big/little endian flags are inter-dependent */
        if (new_flags & LIBNDR_FLAG_LITTLE_ENDIAN) {
                (*pflags) &= ~LIBNDR_FLAG_BIGENDIAN;
        }
        if (new_flags & LIBNDR_FLAG_BIGENDIAN) {
                (*pflags) &= ~LIBNDR_FLAG_LITTLE_ENDIAN;
        }
        if (new_flags & LIBNDR_FLAG_REMAINING) {
                (*pflags) &= ~LIBNDR_ALIGN_FLAGS;
        }
        if (new_flags & LIBNDR_ALIGN_FLAGS) {
                (*pflags) &= ~LIBNDR_FLAG_REMAINING;
        }
        (*pflags) |= new_flags;
}

static NTSTATUS ndr_map_error(enum ndr_err_code ndr_err)
{
        switch (ndr_err) {
        case NDR_ERR_BUFSIZE:
                return NT_STATUS_BUFFER_TOO_SMALL;
        case NDR_ERR_TOKEN:
                return NT_STATUS_INTERNAL_ERROR;
        case NDR_ERR_ALLOC:
                return NT_STATUS_NO_MEMORY;
        case NDR_ERR_ARRAY_SIZE:
                return NT_STATUS_ARRAY_BOUNDS_EXCEEDED;
        default:
                break;
        }

        /* we should map all error codes to different status codes */
        return NT_STATUS_INVALID_PARAMETER;
}

/*
  return and possibly log an NDR error
*/
NTSTATUS ndr_pull_error(struct ndr_pull *ndr,
                                 enum ndr_err_code ndr_err,
                                 const char *format, ...) _PRINTF_ATTRIBUTE(3,4)
{
        char *s=NULL;
        va_list ap;

        va_start(ap, format);
        vasprintf(&s, format, ap);
        va_end(ap);

        DEBUG(3,("ndr_pull_error(%u): %s\n", ndr_err, s));

        free(s);

        return ndr_map_error(ndr_err);
}

/*
  return and possibly log an NDR error
*/
NTSTATUS ndr_push_error(struct ndr_push *ndr,
                                 enum ndr_err_code ndr_err,
                                 const char *format, ...)  _PRINTF_ATTRIBUTE(3,4)
{
        char *s=NULL;
        va_list ap;

        va_start(ap, format);
        vasprintf(&s, format, ap);
        va_end(ap);

        DEBUG(3,("ndr_push_error(%u): %s\n", ndr_err, s));

        free(s);

        return ndr_map_error(ndr_err);
}

/*
  handle subcontext buffers, which in midl land are user-marshalled, but
  we use magic in pidl to make them easier to cope with
*/
NTSTATUS ndr_pull_subcontext_start(struct ndr_pull *ndr, 
                                   struct ndr_pull **_subndr,
                                   size_t header_size,
                                   ssize_t size_is)
{
        struct ndr_pull *subndr;
        uint32_t r_content_size;

        switch (header_size) {
        case 0: {
                uint32_t content_size = ndr->data_size - ndr->offset;
                if (size_is >= 0) {
                        content_size = size_is;
                }
                r_content_size = content_size;
                break;
        }

        case 2: {
                uint16_t content_size;
                NDR_CHECK(ndr_pull_uint16(ndr, NDR_SCALARS, &content_size));
                if (size_is >= 0 && size_is != content_size) {
                        return ndr_pull_error(ndr, NDR_ERR_SUBCONTEXT, "Bad subcontext (PULL) size_is(%d) mismatch content_size %d", 
                                                (int)size_is, (int)content_size);
                }
                r_content_size = content_size;
                break;
        }

        case 4: {
                uint32_t content_size;
                NDR_CHECK(ndr_pull_uint32(ndr, NDR_SCALARS, &content_size));
                if (size_is >= 0 && size_is != content_size) {
                        return ndr_pull_error(ndr, NDR_ERR_SUBCONTEXT, "Bad subcontext (PULL) size_is(%d) mismatch content_size %d", 
                                                (int)size_is, (int)content_size);
                }
                r_content_size = content_size;
                break;
        }
        default:
                return ndr_pull_error(ndr, NDR_ERR_SUBCONTEXT, "Bad subcontext (PULL) header_size %d", 
                                      (int)header_size);
        }

        NDR_PULL_NEED_BYTES(ndr, r_content_size);

        subndr = talloc_zero(ndr, struct ndr_pull);
        NT_STATUS_HAVE_NO_MEMORY(subndr);
        subndr->flags           = ndr->flags;
        subndr->current_mem_ctx = ndr->current_mem_ctx;

        subndr->data = ndr->data + ndr->offset;
        subndr->offset = 0;
        subndr->data_size = r_content_size;

        *_subndr = subndr;
        return NT_STATUS_OK;
}

NTSTATUS ndr_pull_subcontext_end(struct ndr_pull *ndr, 
                                 struct ndr_pull *subndr,
                                 size_t header_size,
                                 ssize_t size_is)
{
        uint32_t advance;
        if (size_is >= 0) {
                advance = size_is;
        } else if (header_size > 0) {
                advance = subndr->data_size;
        } else {
                advance = subndr->offset;
        }
        NDR_CHECK(ndr_pull_advance(ndr, advance));
        return NT_STATUS_OK;
}

NTSTATUS ndr_push_subcontext_start(struct ndr_push *ndr,
                                   struct ndr_push **_subndr,
                                   size_t header_size,
                                   ssize_t size_is)
{
        struct ndr_push *subndr;

        subndr = ndr_push_init_ctx(ndr);
        NT_STATUS_HAVE_NO_MEMORY(subndr);
        subndr->flags   = ndr->flags;

        *_subndr = subndr;
        return NT_STATUS_OK;
}

/*
  push a subcontext header 
*/
NTSTATUS ndr_push_subcontext_end(struct ndr_push *ndr,
                                 struct ndr_push *subndr,
                                 size_t header_size,
                                 ssize_t size_is)
{
        if (size_is >= 0) {
                ssize_t padding_len = size_is - subndr->offset;
                if (padding_len > 0) {
                        NDR_CHECK(ndr_push_zero(subndr, padding_len));
                } else if (padding_len < 0) {
                        return ndr_push_error(ndr, NDR_ERR_SUBCONTEXT, "Bad subcontext (PUSH) content_size %d is larger than size_is(%d)",
                                              (int)subndr->offset, (int)size_is);
                }
        }

        switch (header_size) {
        case 0: 
                break;

        case 2: 
                NDR_CHECK(ndr_push_uint16(ndr, NDR_SCALARS, subndr->offset));
                break;

        case 4: 
                NDR_CHECK(ndr_push_uint32(ndr, NDR_SCALARS, subndr->offset));
                break;

        default:
                return ndr_push_error(ndr, NDR_ERR_SUBCONTEXT, "Bad subcontext header size %d", 
                                      (int)header_size);
        }

        NDR_CHECK(ndr_push_bytes(ndr, subndr->data, subndr->offset));
        return NT_STATUS_OK;
}

/*
  store a token in the ndr context, for later retrieval
*/
NTSTATUS ndr_token_store(TALLOC_CTX *mem_ctx, 
                         struct ndr_token_list **list, 
                         const void *key, 
                         uint32_t value)
{
        struct ndr_token_list *tok;
        tok = talloc(mem_ctx, struct ndr_token_list);
        if (tok == NULL) {
                return NT_STATUS_NO_MEMORY;
        }
        tok->key = key;
        tok->value = value;
        DLIST_ADD((*list), tok);
        return NT_STATUS_OK;
}

/*
  retrieve a token from a ndr context, using cmp_fn to match the tokens
*/
NTSTATUS ndr_token_retrieve_cmp_fn(struct ndr_token_list **list, const void *key, uint32_t *v,
                                   comparison_fn_t _cmp_fn, BOOL _remove_tok)
{
        struct ndr_token_list *tok;
        for (tok=*list;tok;tok=tok->next) {
                if (_cmp_fn && _cmp_fn(tok->key,key)==0) goto found;
                else if (!_cmp_fn && tok->key == key) goto found;
        }
        return ndr_map_error(NDR_ERR_TOKEN);
found:
        *v = tok->value;
        if (_remove_tok) {
                DLIST_REMOVE((*list), tok);
                talloc_free(tok);
        }
        return NT_STATUS_OK;            
}

/*
  retrieve a token from a ndr context
*/
NTSTATUS ndr_token_retrieve(struct ndr_token_list **list, const void *key, uint32_t *v)
{
        return ndr_token_retrieve_cmp_fn(list, key, v, NULL, True);
}

/*
  peek at but don't removed a token from a ndr context
*/
uint32_t ndr_token_peek(struct ndr_token_list **list, const void *key)
{
        NTSTATUS status;
        uint32_t v;
        status = ndr_token_retrieve_cmp_fn(list, key, &v, NULL, False);
        if (NT_STATUS_IS_OK(status)) return v;
        return 0;
}

/*
  pull an array size field and add it to the array_size_list token list
*/
NTSTATUS ndr_pull_array_size(struct ndr_pull *ndr, const void *p)
{
        uint32_t size;
        NDR_CHECK(ndr_pull_uint32(ndr, NDR_SCALARS, &size));
        return ndr_token_store(ndr, &ndr->array_size_list, p, size);
}

/*
  get the stored array size field
*/
uint32_t ndr_get_array_size(struct ndr_pull *ndr, const void *p)
{
        return ndr_token_peek(&ndr->array_size_list, p);
}

/*
  check the stored array size field
*/
NTSTATUS ndr_check_array_size(struct ndr_pull *ndr, void *p, uint32_t size)
{
        uint32_t stored;
        stored = ndr_token_peek(&ndr->array_size_list, p);
        if (stored != size) {
                return ndr_pull_error(ndr, NDR_ERR_ARRAY_SIZE, 
                                      "Bad array size - got %u expected %u\n",
                                      stored, size);
        }
        return NT_STATUS_OK;
}

/*
  pull an array length field and add it to the array_length_list token list
*/
NTSTATUS ndr_pull_array_length(struct ndr_pull *ndr, const void *p)
{
        uint32_t length, offset;
        NDR_CHECK(ndr_pull_uint32(ndr, NDR_SCALARS, &offset));
        if (offset != 0) {
                return ndr_pull_error(ndr, NDR_ERR_ARRAY_SIZE, 
                                      "non-zero array offset %u\n", offset);
        }
        NDR_CHECK(ndr_pull_uint32(ndr, NDR_SCALARS, &length));
        return ndr_token_store(ndr, &ndr->array_length_list, p, length);
}

/*
  get the stored array length field
*/
uint32_t ndr_get_array_length(struct ndr_pull *ndr, const void *p)
{
        return ndr_token_peek(&ndr->array_length_list, p);
}

/*
  check the stored array length field
*/
NTSTATUS ndr_check_array_length(struct ndr_pull *ndr, void *p, uint32_t length)
{
        uint32_t stored;
        stored = ndr_token_peek(&ndr->array_length_list, p);
        if (stored != length) {
                return ndr_pull_error(ndr, NDR_ERR_ARRAY_SIZE, 
                                      "Bad array length - got %u expected %u\n",
                                      stored, length);
        }
        return NT_STATUS_OK;
}

/*
  store a switch value
 */
NTSTATUS ndr_push_set_switch_value(struct ndr_push *ndr, const void *p, uint32_t val)
{
        return ndr_token_store(ndr, &ndr->switch_list, p, val);
}

NTSTATUS ndr_pull_set_switch_value(struct ndr_pull *ndr, const void *p, uint32_t val)
{
        return ndr_token_store(ndr, &ndr->switch_list, p, val);
}

NTSTATUS ndr_print_set_switch_value(struct ndr_print *ndr, const void *p, uint32_t val)
{
        return ndr_token_store(ndr, &ndr->switch_list, p, val);
}

/*
  retrieve a switch value
 */
uint32_t ndr_push_get_switch_value(struct ndr_push *ndr, const void *p)
{
        return ndr_token_peek(&ndr->switch_list, p);
}

uint32_t ndr_pull_get_switch_value(struct ndr_pull *ndr, const void *p)
{
        return ndr_token_peek(&ndr->switch_list, p);
}

uint32_t ndr_print_get_switch_value(struct ndr_print *ndr, const void *p)
{
        return ndr_token_peek(&ndr->switch_list, p);
}

/*
  pull a struct from a blob using NDR
*/
NTSTATUS ndr_pull_struct_blob(const DATA_BLOB *blob, TALLOC_CTX *mem_ctx, void *p,
                              ndr_pull_flags_fn_t fn)
{
        struct ndr_pull *ndr;
        ndr = ndr_pull_init_blob(blob, mem_ctx);
        if (!ndr) {
                return NT_STATUS_NO_MEMORY;
        }
        return fn(ndr, NDR_SCALARS|NDR_BUFFERS, p);
}

/*
  pull a struct from a blob using NDR - failing if all bytes are not consumed
*/
NTSTATUS ndr_pull_struct_blob_all(const DATA_BLOB *blob, TALLOC_CTX *mem_ctx, void *p,
                                  ndr_pull_flags_fn_t fn)
{
        struct ndr_pull *ndr;
        NTSTATUS status;

        ndr = ndr_pull_init_blob(blob, mem_ctx);
        if (!ndr) {
                return NT_STATUS_NO_MEMORY;
        }
        status = fn(ndr, NDR_SCALARS|NDR_BUFFERS, p);
        if (!NT_STATUS_IS_OK(status)) return status;
        if (ndr->offset != ndr->data_size) {
                return NT_STATUS_BUFFER_TOO_SMALL;
        }
        return status;
}

/*
  pull a union from a blob using NDR, given the union discriminator
*/
NTSTATUS ndr_pull_union_blob(const DATA_BLOB *blob, TALLOC_CTX *mem_ctx, void *p,
                             uint32_t level, ndr_pull_flags_fn_t fn)
{
        struct ndr_pull *ndr;
        NTSTATUS status;

        ndr = ndr_pull_init_blob(blob, mem_ctx);
        if (!ndr) {
                return NT_STATUS_NO_MEMORY;
        }
        ndr_pull_set_switch_value(ndr, p, level);
        status = fn(ndr, NDR_SCALARS|NDR_BUFFERS, p);
        if (!NT_STATUS_IS_OK(status)) return status;
        if (ndr->offset != ndr->data_size) {
                return NT_STATUS_BUFFER_TOO_SMALL;
        }
        return status;
}

/*
  push a struct to a blob using NDR
*/
NTSTATUS ndr_push_struct_blob(DATA_BLOB *blob, TALLOC_CTX *mem_ctx, const void *p,
                              ndr_push_flags_fn_t fn)
{
        NTSTATUS status;
        struct ndr_push *ndr;
        ndr = ndr_push_init_ctx(mem_ctx);
        if (!ndr) {
                return NT_STATUS_NO_MEMORY;
        }
        status = fn(ndr, NDR_SCALARS|NDR_BUFFERS, p);
        if (!NT_STATUS_IS_OK(status)) {
                return status;
        }

        *blob = ndr_push_blob(ndr);

        return NT_STATUS_OK;
}

/*
  push a union to a blob using NDR
*/
NTSTATUS ndr_push_union_blob(DATA_BLOB *blob, TALLOC_CTX *mem_ctx, void *p,
                             uint32_t level, ndr_push_flags_fn_t fn)
{
        NTSTATUS status;
        struct ndr_push *ndr;
        ndr = ndr_push_init_ctx(mem_ctx);
        if (!ndr) {
                return NT_STATUS_NO_MEMORY;
        }
        ndr_push_set_switch_value(ndr, p, level);
        status = fn(ndr, NDR_SCALARS|NDR_BUFFERS, p);
        if (!NT_STATUS_IS_OK(status)) {
                return status;
        }

        *blob = ndr_push_blob(ndr);

        return NT_STATUS_OK;
}

/*
  generic ndr_size_*() handler for structures
*/
size_t ndr_size_struct(const void *p, int flags, ndr_push_flags_fn_t push)
{
        struct ndr_push *ndr;
        NTSTATUS status;
        size_t ret;

        /* avoid recursion */
        if (flags & LIBNDR_FLAG_NO_NDR_SIZE) return 0;

        ndr = ndr_push_init_ctx(NULL);
        if (!ndr) return 0;
        ndr->flags |= flags | LIBNDR_FLAG_NO_NDR_SIZE;
        status = push(ndr, NDR_SCALARS|NDR_BUFFERS, p);
        if (!NT_STATUS_IS_OK(status)) {
                return 0;
        }
        ret = ndr->offset;
        talloc_free(ndr);
        return ret;
}

/*
  generic ndr_size_*() handler for unions
*/
size_t ndr_size_union(const void *p, int flags, uint32_t level, ndr_push_flags_fn_t push)
{
        struct ndr_push *ndr;
        NTSTATUS status;
        size_t ret;

        /* avoid recursion */
        if (flags & LIBNDR_FLAG_NO_NDR_SIZE) return 0;

        ndr = ndr_push_init_ctx(NULL);
        if (!ndr) return 0;
        ndr->flags |= flags | LIBNDR_FLAG_NO_NDR_SIZE;
        ndr_push_set_switch_value(ndr, p, level);
        status = push(ndr, NDR_SCALARS|NDR_BUFFERS, p);
        if (!NT_STATUS_IS_OK(status)) {
                return 0;
        }
        ret = ndr->offset;
        talloc_free(ndr);
        return ret;
}

/*
  get the current base for relative pointers for the push
*/
uint32_t ndr_push_get_relative_base_offset(struct ndr_push *ndr)
{
        return ndr->relative_base_offset;
}

/*
  restore the old base for relative pointers for the push
*/
void ndr_push_restore_relative_base_offset(struct ndr_push *ndr, uint32_t offset)
{
        ndr->relative_base_offset = offset;
}

/*
  setup the current base for relative pointers for the push
  called in the NDR_SCALAR stage
*/
NTSTATUS ndr_push_setup_relative_base_offset1(struct ndr_push *ndr, const void *p, uint32_t offset)
{
        ndr->relative_base_offset = offset;
        return ndr_token_store(ndr, &ndr->relative_base_list, p, offset);
}

/*
  setup the current base for relative pointers for the push
  called in the NDR_BUFFERS stage
*/
NTSTATUS ndr_push_setup_relative_base_offset2(struct ndr_push *ndr, const void *p)
{
        return ndr_token_retrieve(&ndr->relative_base_list, p, &ndr->relative_base_offset);
}

/*
  push a relative object - stage1
  this is called during SCALARS processing
*/
NTSTATUS ndr_push_relative_ptr1(struct ndr_push *ndr, const void *p)
{
        if (p == NULL) {
                NDR_CHECK(ndr_push_uint32(ndr, NDR_SCALARS, 0));
                return NT_STATUS_OK;
        }
        NDR_CHECK(ndr_push_align(ndr, 4));
        NDR_CHECK(ndr_token_store(ndr, &ndr->relative_list, p, ndr->offset));
        return ndr_push_uint32(ndr, NDR_SCALARS, 0xFFFFFFFF);
}

/*
  push a relative object - stage2
  this is called during buffers processing
*/
NTSTATUS ndr_push_relative_ptr2(struct ndr_push *ndr, const void *p)
{
        struct ndr_push_save save;
        uint32_t ptr_offset = 0xFFFFFFFF;
        if (p == NULL) {
                return NT_STATUS_OK;
        }
        ndr_push_save(ndr, &save);
        NDR_CHECK(ndr_token_retrieve(&ndr->relative_list, p, &ptr_offset));
        if (ptr_offset > ndr->offset) {
                return ndr_push_error(ndr, NDR_ERR_BUFSIZE, 
                                      "ndr_push_relative_ptr2 ptr_offset(%u) > ndr->offset(%u)",
                                      ptr_offset, ndr->offset);
        }
        ndr->offset = ptr_offset;
        if (save.offset < ndr->relative_base_offset) {
                return ndr_push_error(ndr, NDR_ERR_BUFSIZE, 
                                      "ndr_push_relative_ptr2 save.offset(%u) < ndr->relative_base_offset(%u)",
                                      save.offset, ndr->relative_base_offset);
        }       
        NDR_CHECK(ndr_push_uint32(ndr, NDR_SCALARS, save.offset - ndr->relative_base_offset));
        ndr_push_restore(ndr, &save);
        return NT_STATUS_OK;
}

/*
  get the current base for relative pointers for the pull
*/
uint32_t ndr_pull_get_relative_base_offset(struct ndr_pull *ndr)
{
        return ndr->relative_base_offset;
}

/*
  restore the old base for relative pointers for the pull
*/
void ndr_pull_restore_relative_base_offset(struct ndr_pull *ndr, uint32_t offset)
{
        ndr->relative_base_offset = offset;
}

/*
  setup the current base for relative pointers for the pull
  called in the NDR_SCALAR stage
*/
NTSTATUS ndr_pull_setup_relative_base_offset1(struct ndr_pull *ndr, const void *p, uint32_t offset)
{
        ndr->relative_base_offset = offset;
        return ndr_token_store(ndr, &ndr->relative_base_list, p, offset);
}

/*
  setup the current base for relative pointers for the pull
  called in the NDR_BUFFERS stage
*/
NTSTATUS ndr_pull_setup_relative_base_offset2(struct ndr_pull *ndr, const void *p)
{
        return ndr_token_retrieve(&ndr->relative_base_list, p, &ndr->relative_base_offset);
}

/*
  pull a relative object - stage1
  called during SCALARS processing
*/
NTSTATUS ndr_pull_relative_ptr1(struct ndr_pull *ndr, const void *p, uint32_t rel_offset)
{
        rel_offset += ndr->relative_base_offset;
        if (rel_offset > ndr->data_size) {
                return ndr_pull_error(ndr, NDR_ERR_BUFSIZE, 
                                      "ndr_pull_relative_ptr1 rel_offset(%u) > ndr->data_size(%u)",
                                      rel_offset, ndr->data_size);
        }
        return ndr_token_store(ndr, &ndr->relative_list, p, rel_offset);
}

/*
  pull a relative object - stage2
  called during BUFFERS processing
*/
NTSTATUS ndr_pull_relative_ptr2(struct ndr_pull *ndr, const void *p)
{
        uint32_t rel_offset;
        NDR_CHECK(ndr_token_retrieve(&ndr->relative_list, p, &rel_offset));
        return ndr_pull_set_offset(ndr, rel_offset);
}

---