source: trunk/samba/source/rpc_parse/parse_prs.c @ 30

/* 
   Unix SMB/CIFS implementation.
   Samba memory buffer functions
   Copyright (C) Andrew Tridgell              1992-1997
   Copyright (C) Luke Kenneth Casson Leighton 1996-1997
   Copyright (C) Jeremy Allison               1999
   Copyright (C) Andrew Bartlett              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.
*/

#include "includes.h"

#undef DBGC_CLASS
#define DBGC_CLASS DBGC_RPC_PARSE

/**
 * Dump a prs to a file: from the current location through to the end.
 **/
void prs_dump(char *name, int v, prs_struct *ps)
{
        prs_dump_region(name, v, ps, ps->data_offset, ps->buffer_size);
}

/**
 * Dump from the start of the prs to the current location.
 **/
void prs_dump_before(char *name, int v, prs_struct *ps)
{
        prs_dump_region(name, v, ps, 0, ps->data_offset);
}

/**
 * Dump everything from the start of the prs up to the current location.
 **/
void prs_dump_region(char *name, int v, prs_struct *ps,
                     int from_off, int to_off)
{
        int fd, i;
        pstring fname;
        ssize_t sz;
        if (DEBUGLEVEL < 50) return;
        for (i=1;i<100;i++) {
                if (v != -1) {
                        slprintf(fname,sizeof(fname)-1, "/tmp/%s_%d.%d.prs", name, v, i);
                } else {
                        slprintf(fname,sizeof(fname)-1, "/tmp/%s.%d.prs", name, i);
                }
                fd = open(fname, O_WRONLY|O_CREAT|O_EXCL, 0644);
                if (fd != -1 || errno != EEXIST) break;
        }
        if (fd != -1) {
                sz = write(fd, ps->data_p + from_off, to_off - from_off);
                i = close(fd);
                if ( (sz != to_off-from_off) || (i != 0) ) {
                        DEBUG(0,("Error writing/closing %s: %ld!=%ld %d\n", fname, (unsigned long)sz, (unsigned long)to_off-from_off, i ));
                } else {
                        DEBUG(0,("created %s\n", fname));
                }
        }
}

/*******************************************************************
 Debug output for parsing info

 XXXX side-effect of this function is to increase the debug depth XXXX.

********************************************************************/

void prs_debug(prs_struct *ps, int depth, const char *desc, const char *fn_name)
{
        DEBUG(5+depth, ("%s%06x %s %s\n", tab_depth(depth), ps->data_offset, fn_name, desc));
}

/**
 * Initialise an expandable parse structure.
 *
 * @param size Initial buffer size.  If >0, a new buffer will be
 * created with malloc().
 *
 * @return False if allocation fails, otherwise True.
 **/

BOOL prs_init(prs_struct *ps, uint32 size, TALLOC_CTX *ctx, BOOL io)
{
        ZERO_STRUCTP(ps);
        ps->io = io;
        ps->bigendian_data = RPC_LITTLE_ENDIAN;
        ps->align = RPC_PARSE_ALIGN;
        ps->is_dynamic = False;
        ps->data_offset = 0;
        ps->buffer_size = 0;
        ps->data_p = NULL;
        ps->mem_ctx = ctx;

        if (size != 0) {
                ps->buffer_size = size;
                if((ps->data_p = (char *)SMB_MALLOC((size_t)size)) == NULL) {
                        DEBUG(0,("prs_init: malloc fail for %u bytes.\n", (unsigned int)size));
                        return False;
                }
                memset(ps->data_p, '\0', (size_t)size);
                ps->is_dynamic = True; /* We own this memory. */
        } else if (MARSHALLING(ps)) {
                /* If size is zero and we're marshalling we should allocate memory on demand. */
                ps->is_dynamic = True;
        }

        return True;
}

/*******************************************************************
 Delete the memory in a parse structure - if we own it.
 ********************************************************************/

void prs_mem_free(prs_struct *ps)
{
        if(ps->is_dynamic)
                SAFE_FREE(ps->data_p);
        ps->is_dynamic = False;
        ps->buffer_size = 0;
        ps->data_offset = 0;
}

/*******************************************************************
 Clear the memory in a parse structure.
 ********************************************************************/

void prs_mem_clear(prs_struct *ps)
{
        if (ps->buffer_size)
                memset(ps->data_p, '\0', (size_t)ps->buffer_size);
}

/*******************************************************************
 Allocate memory when unmarshalling... Always zero clears.
 ********************************************************************/

#if defined(PARANOID_MALLOC_CHECKER)
char *prs_alloc_mem_(prs_struct *ps, size_t size, unsigned int count)
#else
char *prs_alloc_mem(prs_struct *ps, size_t size, unsigned int count)
#endif
{
        char *ret = NULL;

        if (size) {
                /* We can't call the type-safe version here. */
                ret = (char *)_talloc_zero_array(ps->mem_ctx, size, count,
                                                 "parse_prs");
        }
        return ret;
}

/*******************************************************************
 Return the current talloc context we're using.
 ********************************************************************/

TALLOC_CTX *prs_get_mem_context(prs_struct *ps)
{
        return ps->mem_ctx;
}

/*******************************************************************
 Hand some already allocated memory to a prs_struct.
 ********************************************************************/

void prs_give_memory(prs_struct *ps, char *buf, uint32 size, BOOL is_dynamic)
{
        ps->is_dynamic = is_dynamic;
        ps->data_p = buf;
        ps->buffer_size = size;
}

/*******************************************************************
 Take some memory back from a prs_struct.
 ********************************************************************/

char *prs_take_memory(prs_struct *ps, uint32 *psize)
{
        char *ret = ps->data_p;
        if(psize)
                *psize = ps->buffer_size;
        ps->is_dynamic = False;
        prs_mem_free(ps);
        return ret;
}

/*******************************************************************
 Set a prs_struct to exactly a given size. Will grow or tuncate if neccessary.
 ********************************************************************/

BOOL prs_set_buffer_size(prs_struct *ps, uint32 newsize)
{
        if (newsize > ps->buffer_size)
                return prs_force_grow(ps, newsize - ps->buffer_size);

        if (newsize < ps->buffer_size) {
                ps->buffer_size = newsize;

                /* newsize == 0 acts as a free and set pointer to NULL */
                if (newsize == 0) {
                        SAFE_FREE(ps->data_p);
                } else {
                        ps->data_p = (char *)SMB_REALLOC(ps->data_p, newsize);

                        if (ps->data_p == NULL) {
                                DEBUG(0,("prs_set_buffer_size: Realloc failure for size %u.\n",
                                        (unsigned int)newsize));
                                DEBUG(0,("prs_set_buffer_size: Reason %s\n",strerror(errno)));
                                return False;
                        }
                }
        }

        return True;
}

/*******************************************************************
 Attempt, if needed, to grow a data buffer.
 Also depends on the data stream mode (io).
 ********************************************************************/

BOOL prs_grow(prs_struct *ps, uint32 extra_space)
{
        uint32 new_size;

        ps->grow_size = MAX(ps->grow_size, ps->data_offset + extra_space);

        if(ps->data_offset + extra_space <= ps->buffer_size)
                return True;

        /*
         * We cannot grow the buffer if we're not reading
         * into the prs_struct, or if we don't own the memory.
         */

        if(UNMARSHALLING(ps) || !ps->is_dynamic) {
                DEBUG(0,("prs_grow: Buffer overflow - unable to expand buffer by %u bytes.\n",
                                (unsigned int)extra_space));
                return False;
        }
        
        /*
         * Decide how much extra space we really need.
         */

        extra_space -= (ps->buffer_size - ps->data_offset);
        if(ps->buffer_size == 0) {
                /*
                 * Ensure we have at least a PDU's length, or extra_space, whichever
                 * is greater.
                 */

                new_size = MAX(RPC_MAX_PDU_FRAG_LEN,extra_space);

                if((ps->data_p = (char *)SMB_MALLOC(new_size)) == NULL) {
                        DEBUG(0,("prs_grow: Malloc failure for size %u.\n", (unsigned int)new_size));
                        return False;
                }
                memset(ps->data_p, '\0', (size_t)new_size );
        } else {
                /*
                 * If the current buffer size is bigger than the space needed, just 
                 * double it, else add extra_space.
                 */
                new_size = MAX(ps->buffer_size*2, ps->buffer_size + extra_space);               

                if ((ps->data_p = (char *)SMB_REALLOC(ps->data_p, new_size)) == NULL) {
                        DEBUG(0,("prs_grow: Realloc failure for size %u.\n",
                                (unsigned int)new_size));
                        return False;
                }

                memset(&ps->data_p[ps->buffer_size], '\0', (size_t)(new_size - ps->buffer_size));
        }
        ps->buffer_size = new_size;

        return True;
}

/*******************************************************************
 Attempt to force a data buffer to grow by len bytes.
 This is only used when appending more data onto a prs_struct
 when reading an rpc reply, before unmarshalling it.
 ********************************************************************/

BOOL prs_force_grow(prs_struct *ps, uint32 extra_space)
{
        uint32 new_size = ps->buffer_size + extra_space;

        if(!UNMARSHALLING(ps) || !ps->is_dynamic) {
                DEBUG(0,("prs_force_grow: Buffer overflow - unable to expand buffer by %u bytes.\n",
                                (unsigned int)extra_space));
                return False;
        }

        if((ps->data_p = (char *)SMB_REALLOC(ps->data_p, new_size)) == NULL) {
                DEBUG(0,("prs_force_grow: Realloc failure for size %u.\n",
                        (unsigned int)new_size));
                return False;
        }

        memset(&ps->data_p[ps->buffer_size], '\0', (size_t)(new_size - ps->buffer_size));

        ps->buffer_size = new_size;

        return True;
}

/*******************************************************************
 Get the data pointer (external interface).
********************************************************************/

char *prs_data_p(prs_struct *ps)
{
        return ps->data_p;
}

/*******************************************************************
 Get the current data size (external interface).
 ********************************************************************/

uint32 prs_data_size(prs_struct *ps)
{
        return ps->buffer_size;
}

/*******************************************************************
 Fetch the current offset (external interface).
 ********************************************************************/

uint32 prs_offset(prs_struct *ps)
{
        return ps->data_offset;
}

/*******************************************************************
 Set the current offset (external interface).
 ********************************************************************/

BOOL prs_set_offset(prs_struct *ps, uint32 offset)
{
        if(offset <= ps->data_offset) {
                ps->data_offset = offset;
                return True;
        }

        if(!prs_grow(ps, offset - ps->data_offset))
                return False;

        ps->data_offset = offset;
        return True;
}

/*******************************************************************
 Append the data from one parse_struct into another.
 ********************************************************************/

BOOL prs_append_prs_data(prs_struct *dst, prs_struct *src)
{
        if (prs_offset(src) == 0)
                return True;

        if(!prs_grow(dst, prs_offset(src)))
                return False;

        memcpy(&dst->data_p[dst->data_offset], src->data_p, (size_t)prs_offset(src));
        dst->data_offset += prs_offset(src);

        return True;
}

/*******************************************************************
 Append some data from one parse_struct into another.
 ********************************************************************/

BOOL prs_append_some_prs_data(prs_struct *dst, prs_struct *src, int32 start, uint32 len)
{       
        if (len == 0)
                return True;

        if(!prs_grow(dst, len))
                return False;
        
        memcpy(&dst->data_p[dst->data_offset], src->data_p + start, (size_t)len);
        dst->data_offset += len;

        return True;
}

/*******************************************************************
 Append the data from a buffer into a parse_struct.
 ********************************************************************/

BOOL prs_copy_data_in(prs_struct *dst, const char *src, uint32 len)
{
        if (len == 0)
                return True;

        if(!prs_grow(dst, len))
                return False;

        memcpy(&dst->data_p[dst->data_offset], src, (size_t)len);
        dst->data_offset += len;

        return True;
}

/*******************************************************************
 Copy some data from a parse_struct into a buffer.
 ********************************************************************/

BOOL prs_copy_data_out(char *dst, prs_struct *src, uint32 len)
{
        if (len == 0)
                return True;

        if(!prs_mem_get(src, len))
                return False;

        memcpy(dst, &src->data_p[src->data_offset], (size_t)len);
        src->data_offset += len;

        return True;
}

/*******************************************************************
 Copy all the data from a parse_struct into a buffer.
 ********************************************************************/

BOOL prs_copy_all_data_out(char *dst, prs_struct *src)
{
        uint32 len = prs_offset(src);

        if (!len)
                return True;

        prs_set_offset(src, 0);
        return prs_copy_data_out(dst, src, len);
}

/*******************************************************************
 Set the data as X-endian (external interface).
 ********************************************************************/

void prs_set_endian_data(prs_struct *ps, BOOL endian)
{
        ps->bigendian_data = endian;
}

/*******************************************************************
 Align a the data_len to a multiple of align bytes - filling with
 zeros.
 ********************************************************************/

BOOL prs_align(prs_struct *ps)
{
        uint32 mod = ps->data_offset & (ps->align-1);

        if (ps->align != 0 && mod != 0) {
                uint32 extra_space = (ps->align - mod);
                if(!prs_grow(ps, extra_space))
                        return False;
                memset(&ps->data_p[ps->data_offset], '\0', (size_t)extra_space);
                ps->data_offset += extra_space;
        }

        return True;
}

/******************************************************************
 Align on a 2 byte boundary
 *****************************************************************/
 
BOOL prs_align_uint16(prs_struct *ps)
{
        BOOL ret;
        uint8 old_align = ps->align;

        ps->align = 2;
        ret = prs_align(ps);
        ps->align = old_align;
        
        return ret;
}

/******************************************************************
 Align on a 8 byte boundary
 *****************************************************************/
 
BOOL prs_align_uint64(prs_struct *ps)
{
        BOOL ret;
        uint8 old_align = ps->align;

        ps->align = 8;
        ret = prs_align(ps);
        ps->align = old_align;
        
        return ret;
}

/******************************************************************
 Align on a specific byte boundary
 *****************************************************************/
 
BOOL prs_align_custom(prs_struct *ps, uint8 boundary)
{
        BOOL ret;
        uint8 old_align = ps->align;

        ps->align = boundary;
        ret = prs_align(ps);
        ps->align = old_align;
        
        return ret;
}



/*******************************************************************
 Align only if required (for the unistr2 string mainly)
 ********************************************************************/

BOOL prs_align_needed(prs_struct *ps, uint32 needed)
{
        if (needed==0)
                return True;
        else
                return prs_align(ps);
}

/*******************************************************************
 Ensure we can read/write to a given offset.
 ********************************************************************/

char *prs_mem_get(prs_struct *ps, uint32 extra_size)
{
        if(UNMARSHALLING(ps)) {
                /*
                 * If reading, ensure that we can read the requested size item.
                 */
                if (ps->data_offset + extra_size > ps->buffer_size) {
                        DEBUG(0,("prs_mem_get: reading data of size %u would overrun "
                                "buffer by %u bytes.\n",
                                (unsigned int)extra_size,
                                (unsigned int)(ps->data_offset + extra_size - ps->buffer_size) ));
                        return NULL;
                }
        } else {
                /*
                 * Writing - grow the buffer if needed.
                 */
                if(!prs_grow(ps, extra_size))
                        return NULL;
        }
        return &ps->data_p[ps->data_offset];
}

/*******************************************************************
 Change the struct type.
 ********************************************************************/

void prs_switch_type(prs_struct *ps, BOOL io)
{
        if ((ps->io ^ io) == True)
                ps->io=io;
}

/*******************************************************************
 Force a prs_struct to be dynamic even when it's size is 0.
 ********************************************************************/

void prs_force_dynamic(prs_struct *ps)
{
        ps->is_dynamic=True;
}

/*******************************************************************
 Associate a session key with a parse struct.
 ********************************************************************/

void prs_set_session_key(prs_struct *ps, const char sess_key[16])
{
        ps->sess_key = sess_key;
}

/*******************************************************************
 Stream a uint8.
 ********************************************************************/

BOOL prs_uint8(const char *name, prs_struct *ps, int depth, uint8 *data8)
{
        char *q = prs_mem_get(ps, 1);
        if (q == NULL)
                return False;

        if (UNMARSHALLING(ps))
                *data8 = CVAL(q,0);
        else
                SCVAL(q,0,*data8);

        DEBUG(5,("%s%04x %s: %02x\n", tab_depth(depth), ps->data_offset, name, *data8));

        ps->data_offset += 1;

        return True;
}

/*******************************************************************
 Stream a uint16* (allocate memory if unmarshalling)
 ********************************************************************/

BOOL prs_pointer( const char *name, prs_struct *ps, int depth, 
                 void *dta, size_t data_size,
                 BOOL(*prs_fn)(const char*, prs_struct*, int, void*) )
{
        void ** data = (void **)dta;
        uint32 data_p;

        /* output f000baaa to stream if the pointer is non-zero. */

        data_p = *data ? 0xf000baaa : 0;

        if ( !prs_uint32("ptr", ps, depth, &data_p ))
                return False;

        /* we're done if there is no data */

        if ( !data_p )
                return True;

        if (UNMARSHALLING(ps)) {
                if ( !(*data = PRS_ALLOC_MEM_VOID(ps, data_size)) )
                        return False;
        }

        return prs_fn(name, ps, depth, *data);
}


/*******************************************************************
 Stream a uint16.
 ********************************************************************/

BOOL prs_uint16(const char *name, prs_struct *ps, int depth, uint16 *data16)
{
        char *q = prs_mem_get(ps, sizeof(uint16));
        if (q == NULL)
                return False;

        if (UNMARSHALLING(ps)) {
                if (ps->bigendian_data)
                        *data16 = RSVAL(q,0);
                else
                        *data16 = SVAL(q,0);
        } else {
                if (ps->bigendian_data)
                        RSSVAL(q,0,*data16);
                else
                        SSVAL(q,0,*data16);
        }

        DEBUG(5,("%s%04x %s: %04x\n", tab_depth(depth), ps->data_offset, name, *data16));

        ps->data_offset += sizeof(uint16);

        return True;
}

/*******************************************************************
 Stream a uint32.
 ********************************************************************/

BOOL prs_uint32(const char *name, prs_struct *ps, int depth, uint32 *data32)
{
        char *q = prs_mem_get(ps, sizeof(uint32));
        if (q == NULL)
                return False;

        if (UNMARSHALLING(ps)) {
                if (ps->bigendian_data)
                        *data32 = RIVAL(q,0);
                else
                        *data32 = IVAL(q,0);
        } else {
                if (ps->bigendian_data)
                        RSIVAL(q,0,*data32);
                else
                        SIVAL(q,0,*data32);
        }

        DEBUG(5,("%s%04x %s: %08x\n", tab_depth(depth), ps->data_offset, name, *data32));

        ps->data_offset += sizeof(uint32);

        return True;
}

/*******************************************************************
 Stream an int32.
 ********************************************************************/

BOOL prs_int32(const char *name, prs_struct *ps, int depth, int32 *data32)
{
        char *q = prs_mem_get(ps, sizeof(int32));
        if (q == NULL)
                return False;

        if (UNMARSHALLING(ps)) {
                if (ps->bigendian_data)
                        *data32 = RIVALS(q,0);
                else
                        *data32 = IVALS(q,0);
        } else {
                if (ps->bigendian_data)
                        RSIVALS(q,0,*data32);
                else
                        SIVALS(q,0,*data32);
        }

        DEBUG(5,("%s%04x %s: %08x\n", tab_depth(depth), ps->data_offset, name, *data32));

        ps->data_offset += sizeof(int32);

        return True;
}

/*******************************************************************
 Stream a NTSTATUS
 ********************************************************************/

BOOL prs_ntstatus(const char *name, prs_struct *ps, int depth, NTSTATUS *status)
{
        char *q = prs_mem_get(ps, sizeof(uint32));
        if (q == NULL)
                return False;

        if (UNMARSHALLING(ps)) {
                if (ps->bigendian_data)
                        *status = NT_STATUS(RIVAL(q,0));
                else
                        *status = NT_STATUS(IVAL(q,0));
        } else {
                if (ps->bigendian_data)
                        RSIVAL(q,0,NT_STATUS_V(*status));
                else
                        SIVAL(q,0,NT_STATUS_V(*status));
        }

        DEBUG(5,("%s%04x %s: %s\n", tab_depth(depth), ps->data_offset, name, 
                 nt_errstr(*status)));

        ps->data_offset += sizeof(uint32);

        return True;
}

/*******************************************************************
 Stream a DCE error code
 ********************************************************************/

BOOL prs_dcerpc_status(const char *name, prs_struct *ps, int depth, NTSTATUS *status)
{
        char *q = prs_mem_get(ps, sizeof(uint32));
        if (q == NULL)
                return False;

        if (UNMARSHALLING(ps)) {
                if (ps->bigendian_data)
                        *status = NT_STATUS(RIVAL(q,0));
                else
                        *status = NT_STATUS(IVAL(q,0));
        } else {
                if (ps->bigendian_data)
                        RSIVAL(q,0,NT_STATUS_V(*status));
                else
                        SIVAL(q,0,NT_STATUS_V(*status));
        }

        DEBUG(5,("%s%04x %s: %s\n", tab_depth(depth), ps->data_offset, name, 
                 dcerpc_errstr(NT_STATUS_V(*status))));

        ps->data_offset += sizeof(uint32);

        return True;
}


/*******************************************************************
 Stream a WERROR
 ********************************************************************/

BOOL prs_werror(const char *name, prs_struct *ps, int depth, WERROR *status)
{
        char *q = prs_mem_get(ps, sizeof(uint32));
        if (q == NULL)
                return False;

        if (UNMARSHALLING(ps)) {
                if (ps->bigendian_data)
                        *status = W_ERROR(RIVAL(q,0));
                else
                        *status = W_ERROR(IVAL(q,0));
        } else {
                if (ps->bigendian_data)
                        RSIVAL(q,0,W_ERROR_V(*status));
                else
                        SIVAL(q,0,W_ERROR_V(*status));
        }

        DEBUG(5,("%s%04x %s: %s\n", tab_depth(depth), ps->data_offset, name, 
                 dos_errstr(*status)));

        ps->data_offset += sizeof(uint32);

        return True;
}


/******************************************************************
 Stream an array of uint8s. Length is number of uint8s.
 ********************************************************************/

BOOL prs_uint8s(BOOL charmode, const char *name, prs_struct *ps, int depth, uint8 *data8s, int len)
{
        int i;
        char *q = prs_mem_get(ps, len);
        if (q == NULL)
                return False;

        if (UNMARSHALLING(ps)) {
                for (i = 0; i < len; i++)
                        data8s[i] = CVAL(q,i);
        } else {
                for (i = 0; i < len; i++)
                        SCVAL(q, i, data8s[i]);
        }

        DEBUG(5,("%s%04x %s: ", tab_depth(depth), ps->data_offset ,name));
        if (charmode)
                print_asc(5, (unsigned char*)data8s, len);
        else {
                for (i = 0; i < len; i++)
                        DEBUG(5,("%02x ", data8s[i]));
        }
        DEBUG(5,("\n"));

        ps->data_offset += len;

        return True;
}

/******************************************************************
 Stream an array of uint16s. Length is number of uint16s.
 ********************************************************************/

BOOL prs_uint16s(BOOL charmode, const char *name, prs_struct *ps, int depth, uint16 *data16s, int len)
{
        int i;
        char *q = prs_mem_get(ps, len * sizeof(uint16));
        if (q == NULL)
                return False;

        if (UNMARSHALLING(ps)) {
                if (ps->bigendian_data) {
                        for (i = 0; i < len; i++)
                                data16s[i] = RSVAL(q, 2*i);
                } else {
                        for (i = 0; i < len; i++)
                                data16s[i] = SVAL(q, 2*i);
                }
        } else {
                if (ps->bigendian_data) {
                        for (i = 0; i < len; i++)
                                RSSVAL(q, 2*i, data16s[i]);
                } else {
                        for (i = 0; i < len; i++)
                                SSVAL(q, 2*i, data16s[i]);
                }
        }

        DEBUG(5,("%s%04x %s: ", tab_depth(depth), ps->data_offset, name));
        if (charmode)
                print_asc(5, (unsigned char*)data16s, 2*len);
        else {
                for (i = 0; i < len; i++)
                        DEBUG(5,("%04x ", data16s[i]));
        }
        DEBUG(5,("\n"));

        ps->data_offset += (len * sizeof(uint16));

        return True;
}

/******************************************************************
 Start using a function for streaming unicode chars. If unmarshalling,
 output must be little-endian, if marshalling, input must be little-endian.
 ********************************************************************/

static void dbg_rw_punival(BOOL charmode, const char *name, int depth, prs_struct *ps,
                                                        char *in_buf, char *out_buf, int len)
{
        int i;

        if (UNMARSHALLING(ps)) {
                if (ps->bigendian_data) {
                        for (i = 0; i < len; i++)
                                SSVAL(out_buf,2*i,RSVAL(in_buf, 2*i));
                } else {
                        for (i = 0; i < len; i++)
                                SSVAL(out_buf, 2*i, SVAL(in_buf, 2*i));
                }
        } else {
                if (ps->bigendian_data) {
                        for (i = 0; i < len; i++)
                                RSSVAL(in_buf, 2*i, SVAL(out_buf,2*i));
                } else {
                        for (i = 0; i < len; i++)
                                SSVAL(in_buf, 2*i, SVAL(out_buf,2*i));
                }
        }

        DEBUG(5,("%s%04x %s: ", tab_depth(depth), ps->data_offset, name));
        if (charmode)
                print_asc(5, (unsigned char*)out_buf, 2*len);
        else {
                for (i = 0; i < len; i++)
                        DEBUG(5,("%04x ", out_buf[i]));
        }
        DEBUG(5,("\n"));
}

/******************************************************************
 Stream a unistr. Always little endian.
 ********************************************************************/

BOOL prs_uint16uni(BOOL charmode, const char *name, prs_struct *ps, int depth, uint16 *data16s, int len)
{
        char *q = prs_mem_get(ps, len * sizeof(uint16));
        if (q == NULL)
                return False;

        dbg_rw_punival(charmode, name, depth, ps, q, (char *)data16s, len);
        ps->data_offset += (len * sizeof(uint16));

        return True;
}

/******************************************************************
 Stream an array of uint32s. Length is number of uint32s.
 ********************************************************************/

BOOL prs_uint32s(BOOL charmode, const char *name, prs_struct *ps, int depth, uint32 *data32s, int len)
{
        int i;
        char *q = prs_mem_get(ps, len * sizeof(uint32));
        if (q == NULL)
                return False;

        if (UNMARSHALLING(ps)) {
                if (ps->bigendian_data) {
                        for (i = 0; i < len; i++)
                                data32s[i] = RIVAL(q, 4*i);
                } else {
                        for (i = 0; i < len; i++)
                                data32s[i] = IVAL(q, 4*i);
                }
        } else {
                if (ps->bigendian_data) {
                        for (i = 0; i < len; i++)
                                RSIVAL(q, 4*i, data32s[i]);
                } else {
                        for (i = 0; i < len; i++)
                                SIVAL(q, 4*i, data32s[i]);
                }
        }

        DEBUG(5,("%s%04x %s: ", tab_depth(depth), ps->data_offset, name));
        if (charmode)
                print_asc(5, (unsigned char*)data32s, 4*len);
        else {
                for (i = 0; i < len; i++)
                        DEBUG(5,("%08x ", data32s[i]));
        }
        DEBUG(5,("\n"));

        ps->data_offset += (len * sizeof(uint32));

        return True;
}

/******************************************************************
 Stream an array of unicode string, length/buffer specified separately,
 in uint16 chars. The unicode string is already in little-endian format.
 ********************************************************************/

BOOL prs_buffer5(BOOL charmode, const char *name, prs_struct *ps, int depth, BUFFER5 *str)
{
        char *p;
        char *q = prs_mem_get(ps, str->buf_len * sizeof(uint16));
        if (q == NULL)
                return False;

        if (UNMARSHALLING(ps)) {
                str->buffer = PRS_ALLOC_MEM(ps,uint16,str->buf_len);
                if (str->buffer == NULL)
                        return False;
        }

        /* If the string is empty, we don't have anything to stream */
        if (str->buf_len==0)
                return True;

        p = (char *)str->buffer;

        dbg_rw_punival(charmode, name, depth, ps, q, p, str->buf_len);
        
        ps->data_offset += (str->buf_len * sizeof(uint16));

        return True;
}

/******************************************************************
 Stream a "not" unicode string, length/buffer specified separately,
 in byte chars. String is in little-endian format.
 ********************************************************************/

BOOL prs_regval_buffer(BOOL charmode, const char *name, prs_struct *ps, int depth, REGVAL_BUFFER *buf)
{
        char *p;
        char *q = prs_mem_get(ps, buf->buf_len);
        if (q == NULL)
                return False;

        if (UNMARSHALLING(ps)) {
                if (buf->buf_len > buf->buf_max_len) {
                        return False;
                }
                if ( buf->buf_max_len ) {
                        buf->buffer = PRS_ALLOC_MEM(ps, uint16, buf->buf_max_len);
                        if ( buf->buffer == NULL )
                                return False;
                }
        }

        p = (char *)buf->buffer;

        dbg_rw_punival(charmode, name, depth, ps, q, p, buf->buf_len/2);
        ps->data_offset += buf->buf_len;

        return True;
}

/******************************************************************
 Stream a string, length/buffer specified separately,
 in uint8 chars.
 ********************************************************************/

BOOL prs_string2(BOOL charmode, const char *name, prs_struct *ps, int depth, STRING2 *str)
{
        unsigned int i;
        char *q = prs_mem_get(ps, str->str_str_len);
        if (q == NULL)
                return False;

        if (UNMARSHALLING(ps)) {
                if (str->str_str_len > str->str_max_len) {
                        return False;
                }
                str->buffer = PRS_ALLOC_MEM(ps,unsigned char, str->str_max_len);
                if (str->buffer == NULL)
                        return False;
        }

        if (UNMARSHALLING(ps)) {
                for (i = 0; i < str->str_str_len; i++)
                        str->buffer[i] = CVAL(q,i);
        } else {
                for (i = 0; i < str->str_str_len; i++)
                        SCVAL(q, i, str->buffer[i]);
        }

        DEBUG(5,("%s%04x %s: ", tab_depth(depth), ps->data_offset, name));
        if (charmode)
                print_asc(5, (unsigned char*)str->buffer, str->str_str_len);
        else {
                for (i = 0; i < str->str_str_len; i++)
                        DEBUG(5,("%02x ", str->buffer[i]));
        }
        DEBUG(5,("\n"));

        ps->data_offset += str->str_str_len;

        return True;
}

/******************************************************************
 Stream a unicode string, length/buffer specified separately,
 in uint16 chars. The unicode string is already in little-endian format.
 ********************************************************************/

BOOL prs_unistr2(BOOL charmode, const char *name, prs_struct *ps, int depth, UNISTR2 *str)
{
        char *p;
        char *q = prs_mem_get(ps, str->uni_str_len * sizeof(uint16));
        if (q == NULL)
                return False;

        /* If the string is empty, we don't have anything to stream */
        if (str->uni_str_len==0)
                return True;

        if (UNMARSHALLING(ps)) {
                if (str->uni_str_len > str->uni_max_len) {
                        return False;
                }
                str->buffer = PRS_ALLOC_MEM(ps,uint16,str->uni_max_len);
                if (str->buffer == NULL)
                        return False;
        }

        p = (char *)str->buffer;

        dbg_rw_punival(charmode, name, depth, ps, q, p, str->uni_str_len);
        
        ps->data_offset += (str->uni_str_len * sizeof(uint16));

        return True;
}

/******************************************************************
 Stream a unicode string, length/buffer specified separately,
 in uint16 chars. The unicode string is already in little-endian format.
 ********************************************************************/

BOOL prs_unistr3(BOOL charmode, const char *name, UNISTR3 *str, prs_struct *ps, int depth)
{
        char *p;
        char *q = prs_mem_get(ps, str->uni_str_len * sizeof(uint16));
        if (q == NULL)
                return False;

        if (UNMARSHALLING(ps)) {
                str->str.buffer = PRS_ALLOC_MEM(ps,uint16,str->uni_str_len);
                if (str->str.buffer == NULL)
                        return False;
        }

        p = (char *)str->str.buffer;

        dbg_rw_punival(charmode, name, depth, ps, q, p, str->uni_str_len);
        ps->data_offset += (str->uni_str_len * sizeof(uint16));

        return True;
}

/*******************************************************************
 Stream a unicode  null-terminated string. As the string is already
 in little-endian format then do it as a stream of bytes.
 ********************************************************************/

BOOL prs_unistr(const char *name, prs_struct *ps, int depth, UNISTR *str)
{
        unsigned int len = 0;
        unsigned char *p = (unsigned char *)str->buffer;
        uint8 *start;
        char *q;
        uint32 max_len;
        uint16* ptr;

        if (MARSHALLING(ps)) {

                for(len = 0; str->buffer[len] != 0; len++)
                        ;

                q = prs_mem_get(ps, (len+1)*2);
                if (q == NULL)
                        return False;

                start = (uint8*)q;

                for(len = 0; str->buffer[len] != 0; len++) {
                        if(ps->bigendian_data) {
                                /* swap bytes - p is little endian, q is big endian. */
                                q[0] = (char)p[1];
                                q[1] = (char)p[0];
                                p += 2;
                                q += 2;
                        } 
                        else 
                        {
                                q[0] = (char)p[0];
                                q[1] = (char)p[1];
                                p += 2;
                                q += 2;
                        }
                }

                /*
                 * even if the string is 'empty' (only an \0 char)
                 * at this point the leading \0 hasn't been parsed.
                 * so parse it now
                 */

                q[0] = 0;
                q[1] = 0;
                q += 2;

                len++;

                DEBUG(5,("%s%04x %s: ", tab_depth(depth), ps->data_offset, name));
                print_asc(5, (unsigned char*)start, 2*len);     
                DEBUG(5, ("\n"));
        }
        else { /* unmarshalling */
        
                uint32 alloc_len = 0;
                q = ps->data_p + prs_offset(ps);

                /*
                 * Work out how much space we need and talloc it.
                 */
                max_len = (ps->buffer_size - ps->data_offset)/sizeof(uint16);

                /* the test of the value of *ptr helps to catch the circumstance
                   where we have an emtpty (non-existent) string in the buffer */
                for ( ptr = (uint16 *)q; *ptr++ && (alloc_len <= max_len); alloc_len++)
                        /* do nothing */ 
                        ;

                if (alloc_len < max_len)
                        alloc_len += 1;

                /* should we allocate anything at all? */
                str->buffer = PRS_ALLOC_MEM(ps,uint16,alloc_len);
                if ((str->buffer == NULL) && (alloc_len > 0))
                        return False;

                p = (unsigned char *)str->buffer;

                len = 0;
                /* the (len < alloc_len) test is to prevent us from overwriting
                   memory that is not ours...if we get that far, we have a non-null
                   terminated string in the buffer and have messed up somewhere */
                while ((len < alloc_len) && (*(uint16 *)q != 0)) {
                        if(ps->bigendian_data) 
                        {
                                /* swap bytes - q is big endian, p is little endian. */
                                p[0] = (unsigned char)q[1];
                                p[1] = (unsigned char)q[0];
                                p += 2;
                                q += 2;
                        } else {

                                p[0] = (unsigned char)q[0];
                                p[1] = (unsigned char)q[1];
                                p += 2;
                                q += 2;
                        }

                        len++;
                } 
                if (len < alloc_len) {
                        /* NULL terminate the UNISTR */
                        str->buffer[len++] = '\0';
                }

                DEBUG(5,("%s%04x %s: ", tab_depth(depth), ps->data_offset, name));
                print_asc(5, (unsigned char*)str->buffer, 2*len);       
                DEBUG(5, ("\n"));
        }

        /* set the offset in the prs_struct; 'len' points to the
           terminiating NULL in the UNISTR so we need to go one more
           uint16 */
        ps->data_offset += (len)*2;
        
        return True;
}


/*******************************************************************
 Stream a null-terminated string.  len is strlen, and therefore does
 not include the null-termination character.
 ********************************************************************/

BOOL prs_string(const char *name, prs_struct *ps, int depth, char *str, int max_buf_size)
{
        char *q;
        int i;
        int len;

        if (UNMARSHALLING(ps))
                len = strlen(&ps->data_p[ps->data_offset]);
        else
                len = strlen(str);

        len = MIN(len, (max_buf_size-1));

        q = prs_mem_get(ps, len+1);
        if (q == NULL)
                return False;

        for(i = 0; i < len; i++) {
                if (UNMARSHALLING(ps))
                        str[i] = q[i];
                else
                        q[i] = str[i];
        }

        /* The terminating null. */
        str[i] = '\0';

        if (MARSHALLING(ps)) {
                q[i] = '\0';
        }

        ps->data_offset += len+1;

        dump_data(5+depth, q, len);

        return True;
}

BOOL prs_string_alloc(const char *name, prs_struct *ps, int depth, const char **str)
{
        size_t len;
        char *tmp_str;

        if (UNMARSHALLING(ps)) {
                len = strlen(&ps->data_p[ps->data_offset]);
        } else {
                len = strlen(*str);
        }

        tmp_str = PRS_ALLOC_MEM(ps, char, len+1);

        if (tmp_str == NULL) {
                return False;
        }

        if (MARSHALLING(ps)) {
                strncpy(tmp_str, *str, len);
        }

        if (!prs_string(name, ps, depth, tmp_str, len+1)) {
                return False;
        }

        *str = tmp_str;
        return True;
}

/*******************************************************************
 prs_uint16 wrapper. Call this and it sets up a pointer to where the
 uint16 should be stored, or gets the size if reading.
 ********************************************************************/

BOOL prs_uint16_pre(const char *name, prs_struct *ps, int depth, uint16 *data16, uint32 *offset)
{
        *offset = ps->data_offset;
        if (UNMARSHALLING(ps)) {
                /* reading. */
                return prs_uint16(name, ps, depth, data16);
        } else {
                char *q = prs_mem_get(ps, sizeof(uint16));
                if(q ==NULL)
                        return False;
                ps->data_offset += sizeof(uint16);
        }
        return True;
}

/*******************************************************************
 prs_uint16 wrapper.  call this and it retrospectively stores the size.
 does nothing on reading, as that is already handled by ...._pre()
 ********************************************************************/

BOOL prs_uint16_post(const char *name, prs_struct *ps, int depth, uint16 *data16,
                                uint32 ptr_uint16, uint32 start_offset)
{
        if (MARSHALLING(ps)) {
                /* 
                 * Writing - temporarily move the offset pointer.
                 */
                uint16 data_size = ps->data_offset - start_offset;
                uint32 old_offset = ps->data_offset;

                ps->data_offset = ptr_uint16;
                if(!prs_uint16(name, ps, depth, &data_size)) {
                        ps->data_offset = old_offset;
                        return False;
                }
                ps->data_offset = old_offset;
        } else {
                ps->data_offset = start_offset + (uint32)(*data16);
        }
        return True;
}

/*******************************************************************
 prs_uint32 wrapper. Call this and it sets up a pointer to where the
 uint32 should be stored, or gets the size if reading.
 ********************************************************************/

BOOL prs_uint32_pre(const char *name, prs_struct *ps, int depth, uint32 *data32, uint32 *offset)
{
        *offset = ps->data_offset;
        if (UNMARSHALLING(ps) && (data32 != NULL)) {
                /* reading. */
                return prs_uint32(name, ps, depth, data32);
        } else {
                ps->data_offset += sizeof(uint32);
        }
        return True;
}

/*******************************************************************
 prs_uint32 wrapper.  call this and it retrospectively stores the size.
 does nothing on reading, as that is already handled by ...._pre()
 ********************************************************************/

BOOL prs_uint32_post(const char *name, prs_struct *ps, int depth, uint32 *data32,
                                uint32 ptr_uint32, uint32 data_size)
{
        if (MARSHALLING(ps)) {
                /* 
                 * Writing - temporarily move the offset pointer.
                 */
                uint32 old_offset = ps->data_offset;
                ps->data_offset = ptr_uint32;
                if(!prs_uint32(name, ps, depth, &data_size)) {
                        ps->data_offset = old_offset;
                        return False;
                }
                ps->data_offset = old_offset;
        }
        return True;
}

/* useful function to store a structure in rpc wire format */
int tdb_prs_store(TDB_CONTEXT *tdb, char *keystr, prs_struct *ps)
{
        TDB_DATA kbuf, dbuf;
        kbuf.dptr = keystr;
        kbuf.dsize = strlen(keystr)+1;
        dbuf.dptr = ps->data_p;
        dbuf.dsize = prs_offset(ps);
        return tdb_trans_store(tdb, kbuf, dbuf, TDB_REPLACE);
}

/* useful function to fetch a structure into rpc wire format */
int tdb_prs_fetch(TDB_CONTEXT *tdb, char *keystr, prs_struct *ps, TALLOC_CTX *mem_ctx)
{
        TDB_DATA kbuf, dbuf;
        kbuf.dptr = keystr;
        kbuf.dsize = strlen(keystr)+1;

        prs_init(ps, 0, mem_ctx, UNMARSHALL);

        dbuf = tdb_fetch(tdb, kbuf);
        if (!dbuf.dptr)
                return -1;

        prs_give_memory(ps, dbuf.dptr, dbuf.dsize, True);

        return 0;
}

/*******************************************************************
 hash a stream.
 ********************************************************************/

BOOL prs_hash1(prs_struct *ps, uint32 offset, int len)
{
        char *q;

        q = ps->data_p;
        q = &q[offset];

#ifdef DEBUG_PASSWORD
        DEBUG(100, ("prs_hash1\n"));
        dump_data(100, ps->sess_key, 16);
        dump_data(100, q, len);
#endif
        SamOEMhash((uchar *) q, (const unsigned char *)ps->sess_key, len);

#ifdef DEBUG_PASSWORD
        dump_data(100, q, len);
#endif

        return True;
}

/*******************************************************************
 Create a digest over the entire packet (including the data), and 
 MD5 it with the session key.
 ********************************************************************/

static void schannel_digest(struct schannel_auth_struct *a,
                          enum pipe_auth_level auth_level,
                          RPC_AUTH_SCHANNEL_CHK * verf,
                          char *data, size_t data_len,
                          uchar digest_final[16]) 
{
        uchar whole_packet_digest[16];
        static uchar zeros[4];
        struct MD5Context ctx3;
        
        /* verfiy the signature on the packet by MD5 over various bits */
        MD5Init(&ctx3);
        /* use our sequence number, which ensures the packet is not
           out of order */
        MD5Update(&ctx3, zeros, sizeof(zeros));
        MD5Update(&ctx3, verf->sig, sizeof(verf->sig));
        if (auth_level == PIPE_AUTH_LEVEL_PRIVACY) {
                MD5Update(&ctx3, verf->confounder, sizeof(verf->confounder));
        }
        MD5Update(&ctx3, (const unsigned char *)data, data_len);
        MD5Final(whole_packet_digest, &ctx3);
        dump_data_pw("whole_packet_digest:\n", whole_packet_digest, sizeof(whole_packet_digest));
        
        /* MD5 this result and the session key, to prove that
           only a valid client could had produced this */
        hmac_md5(a->sess_key, whole_packet_digest, sizeof(whole_packet_digest), digest_final);
}

/*******************************************************************
 Calculate the key with which to encode the data payload 
 ********************************************************************/

static void schannel_get_sealing_key(struct schannel_auth_struct *a,
                                   RPC_AUTH_SCHANNEL_CHK *verf,
                                   uchar sealing_key[16]) 
{
        static uchar zeros[4];
        uchar digest2[16];
        uchar sess_kf0[16];
        int i;

        for (i = 0; i < sizeof(sess_kf0); i++) {
                sess_kf0[i] = a->sess_key[i] ^ 0xf0;
        }
        
        dump_data_pw("sess_kf0:\n", sess_kf0, sizeof(sess_kf0));
        
        /* MD5 of sess_kf0 and 4 zero bytes */
        hmac_md5(sess_kf0, zeros, 0x4, digest2);
        dump_data_pw("digest2:\n", digest2, sizeof(digest2));
        
        /* MD5 of the above result, plus 8 bytes of sequence number */
        hmac_md5(digest2, verf->seq_num, sizeof(verf->seq_num), sealing_key);
        dump_data_pw("sealing_key:\n", sealing_key, 16);
}

/*******************************************************************
 Encode or Decode the sequence number (which is symmetric)
 ********************************************************************/

static void schannel_deal_with_seq_num(struct schannel_auth_struct *a,
                                     RPC_AUTH_SCHANNEL_CHK *verf)
{
        static uchar zeros[4];
        uchar sequence_key[16];
        uchar digest1[16];

        hmac_md5(a->sess_key, zeros, sizeof(zeros), digest1);
        dump_data_pw("(sequence key) digest1:\n", digest1, sizeof(digest1));

        hmac_md5(digest1, verf->packet_digest, 8, sequence_key);

        dump_data_pw("sequence_key:\n", sequence_key, sizeof(sequence_key));

        dump_data_pw("seq_num (before):\n", verf->seq_num, sizeof(verf->seq_num));
        SamOEMhash(verf->seq_num, sequence_key, 8);
        dump_data_pw("seq_num (after):\n", verf->seq_num, sizeof(verf->seq_num));
}

/*******************************************************************
creates an RPC_AUTH_SCHANNEL_CHK structure.
********************************************************************/

static BOOL init_rpc_auth_schannel_chk(RPC_AUTH_SCHANNEL_CHK * chk,
                              const uchar sig[8],
                              const uchar packet_digest[8],
                              const uchar seq_num[8], const uchar confounder[8])
{
        if (chk == NULL)
                return False;

        memcpy(chk->sig, sig, sizeof(chk->sig));
        memcpy(chk->packet_digest, packet_digest, sizeof(chk->packet_digest));
        memcpy(chk->seq_num, seq_num, sizeof(chk->seq_num));
        memcpy(chk->confounder, confounder, sizeof(chk->confounder));

        return True;
}

/*******************************************************************
 Encode a blob of data using the schannel alogrithm, also produceing
 a checksum over the original data.  We currently only support
 signing and sealing togeather - the signing-only code is close, but not
 quite compatible with what MS does.
 ********************************************************************/

void schannel_encode(struct schannel_auth_struct *a, enum pipe_auth_level auth_level,
                   enum schannel_direction direction,
                   RPC_AUTH_SCHANNEL_CHK * verf,
                   char *data, size_t data_len)
{
        uchar digest_final[16];
        uchar confounder[8];
        uchar seq_num[8];
        static const uchar nullbytes[8] = { 0, };

        static const uchar schannel_seal_sig[8] = SCHANNEL_SEAL_SIGNATURE;
        static const uchar schannel_sign_sig[8] = SCHANNEL_SIGN_SIGNATURE;
        const uchar *schannel_sig = NULL;

        DEBUG(10,("SCHANNEL: schannel_encode seq_num=%d data_len=%lu\n", a->seq_num, (unsigned long)data_len));
        
        if (auth_level == PIPE_AUTH_LEVEL_PRIVACY) {
                schannel_sig = schannel_seal_sig;
        } else {
                schannel_sig = schannel_sign_sig;
        }

        /* fill the 'confounder' with random data */
        generate_random_buffer(confounder, sizeof(confounder));

        dump_data_pw("a->sess_key:\n", a->sess_key, sizeof(a->sess_key));

        RSIVAL(seq_num, 0, a->seq_num);

        switch (direction) {
        case SENDER_IS_INITIATOR:
                SIVAL(seq_num, 4, 0x80);
                break;
        case SENDER_IS_ACCEPTOR:
                SIVAL(seq_num, 4, 0x0);
                break;
        }

        dump_data_pw("verf->seq_num:\n", seq_num, sizeof(verf->seq_num));

        init_rpc_auth_schannel_chk(verf, schannel_sig, nullbytes,
                                 seq_num, confounder);
                                
        /* produce a digest of the packet to prove it's legit (before we seal it) */
        schannel_digest(a, auth_level, verf, data, data_len, digest_final);
        memcpy(verf->packet_digest, digest_final, sizeof(verf->packet_digest));

        if (auth_level == PIPE_AUTH_LEVEL_PRIVACY) {
                uchar sealing_key[16];

                /* get the key to encode the data with */
                schannel_get_sealing_key(a, verf, sealing_key);

                /* encode the verification data */
                dump_data_pw("verf->confounder:\n", verf->confounder, sizeof(verf->confounder));
                SamOEMhash(verf->confounder, sealing_key, 8);

                dump_data_pw("verf->confounder_enc:\n", verf->confounder, sizeof(verf->confounder));
                
                /* encode the packet payload */
                dump_data_pw("data:\n", (const unsigned char *)data, data_len);
                SamOEMhash((unsigned char *)data, sealing_key, data_len);
                dump_data_pw("data_enc:\n", (const unsigned char *)data, data_len);
        }

        /* encode the sequence number (key based on packet digest) */
        /* needs to be done after the sealing, as the original version 
           is used in the sealing stuff... */
        schannel_deal_with_seq_num(a, verf);

        return;
}

/*******************************************************************
 Decode a blob of data using the schannel alogrithm, also verifiying
 a checksum over the original data.  We currently can verify signed messages,
 as well as decode sealed messages
 ********************************************************************/

BOOL schannel_decode(struct schannel_auth_struct *a, enum pipe_auth_level auth_level,
                   enum schannel_direction direction, 
                   RPC_AUTH_SCHANNEL_CHK * verf, char *data, size_t data_len)
{
        uchar digest_final[16];

        static const uchar schannel_seal_sig[8] = SCHANNEL_SEAL_SIGNATURE;
        static const uchar schannel_sign_sig[8] = SCHANNEL_SIGN_SIGNATURE;
        const uchar *schannel_sig = NULL;

        uchar seq_num[8];

        DEBUG(10,("SCHANNEL: schannel_decode seq_num=%d data_len=%lu\n", a->seq_num, (unsigned long)data_len));
        
        if (auth_level == PIPE_AUTH_LEVEL_PRIVACY) {
                schannel_sig = schannel_seal_sig;
        } else {
                schannel_sig = schannel_sign_sig;
        }

        /* Create the expected sequence number for comparison */
        RSIVAL(seq_num, 0, a->seq_num);

        switch (direction) {
        case SENDER_IS_INITIATOR:
                SIVAL(seq_num, 4, 0x80);
                break;
        case SENDER_IS_ACCEPTOR:
                SIVAL(seq_num, 4, 0x0);
                break;
        }

        DEBUG(10,("SCHANNEL: schannel_decode seq_num=%d data_len=%lu\n", a->seq_num, (unsigned long)data_len));
        dump_data_pw("a->sess_key:\n", a->sess_key, sizeof(a->sess_key));

        dump_data_pw("seq_num:\n", seq_num, sizeof(seq_num));

        /* extract the sequence number (key based on supplied packet digest) */
        /* needs to be done before the sealing, as the original version 
           is used in the sealing stuff... */
        schannel_deal_with_seq_num(a, verf);

        if (memcmp(verf->seq_num, seq_num, sizeof(seq_num))) {
                /* don't even bother with the below if the sequence number is out */
                /* The sequence number is MD5'ed with a key based on the whole-packet
                   digest, as supplied by the client.  We check that it's a valid 
                   checksum after the decode, below
                */
                DEBUG(2, ("schannel_decode: FAILED: packet sequence number:\n"));
                dump_data(2, (const char*)verf->seq_num, sizeof(verf->seq_num));
                DEBUG(2, ("should be:\n"));
                dump_data(2, (const char*)seq_num, sizeof(seq_num));

                return False;
        }

        if (memcmp(verf->sig, schannel_sig, sizeof(verf->sig))) {
                /* Validate that the other end sent the expected header */
                DEBUG(2, ("schannel_decode: FAILED: packet header:\n"));
                dump_data(2, (const char*)verf->sig, sizeof(verf->sig));
                DEBUG(2, ("should be:\n"));
                dump_data(2, (const char*)schannel_sig, sizeof(schannel_sig));
                return False;
        }

        if (auth_level == PIPE_AUTH_LEVEL_PRIVACY) {
                uchar sealing_key[16];
                
                /* get the key to extract the data with */
                schannel_get_sealing_key(a, verf, sealing_key);

                /* extract the verification data */
                dump_data_pw("verf->confounder:\n", verf->confounder, 
                             sizeof(verf->confounder));
                SamOEMhash(verf->confounder, sealing_key, 8);

                dump_data_pw("verf->confounder_dec:\n", verf->confounder, 
                             sizeof(verf->confounder));
                
                /* extract the packet payload */
                dump_data_pw("data   :\n", (const unsigned char *)data, data_len);
                SamOEMhash((unsigned char *)data, sealing_key, data_len);
                dump_data_pw("datadec:\n", (const unsigned char *)data, data_len);      
        }

        /* digest includes 'data' after unsealing */
        schannel_digest(a, auth_level, verf, data, data_len, digest_final);

        dump_data_pw("Calculated digest:\n", digest_final, 
                     sizeof(digest_final));
        dump_data_pw("verf->packet_digest:\n", verf->packet_digest, 
                     sizeof(verf->packet_digest));
        
        /* compare - if the client got the same result as us, then
           it must know the session key */
        return (memcmp(digest_final, verf->packet_digest, 
                       sizeof(verf->packet_digest)) == 0);
}

/*******************************************************************
creates a new prs_struct containing a DATA_BLOB
********************************************************************/
BOOL prs_init_data_blob(prs_struct *prs, DATA_BLOB *blob, TALLOC_CTX *mem_ctx)
{
        if (!prs_init( prs, RPC_MAX_PDU_FRAG_LEN, mem_ctx, MARSHALL ))
                return False;


        if (!prs_copy_data_in(prs, (char *)blob->data, blob->length))
                return False;

        return True;
}

/*******************************************************************
return the contents of a prs_struct in a DATA_BLOB
********************************************************************/
BOOL prs_data_blob(prs_struct *prs, DATA_BLOB *blob, TALLOC_CTX *mem_ctx)
{
        blob->length = prs_data_size(prs);
        blob->data = (uint8 *)talloc_zero_size(mem_ctx, blob->length);
        
        /* set the pointer at the end of the buffer */
        prs_set_offset( prs, prs_data_size(prs) );

        if (!prs_copy_all_data_out((char *)blob->data, prs))
                return False;
        
        return True;
}