Merged JF's fixes into HEAD. These are for string parsing and SAMR fixes.
[samba.git] / source / rpc_parse / parse_prs.c
1 /* 
2    Unix SMB/Netbios implementation.
3    Version 1.9.
4    Samba memory buffer functions
5    Copyright (C) Andrew Tridgell              1992-1997
6    Copyright (C) Luke Kenneth Casson Leighton 1996-1997
7    Copyright (C) Jeremy Allison 1999.
8    
9    This program is free software; you can redistribute it and/or modify
10    it under the terms of the GNU General Public License as published by
11    the Free Software Foundation; either version 2 of the License, or
12    (at your option) any later version.
13    
14    This program is distributed in the hope that it will be useful,
15    but WITHOUT ANY WARRANTY; without even the implied warranty of
16    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
17    GNU General Public License for more details.
18    
19    You should have received a copy of the GNU General Public License
20    along with this program; if not, write to the Free Software
21    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
22 */
23
24 extern int DEBUGLEVEL;
25
26 #include "includes.h"
27
28
29 /*******************************************************************
30 dump a prs to a file
31  ********************************************************************/
32 void prs_dump(char *name, int v, prs_struct *ps)
33 {
34         int fd, i;
35         pstring fname;
36         if (DEBUGLEVEL < 50) return;
37         for (i=1;i<100;i++) {
38                 if (v != -1) {
39                         slprintf(fname,sizeof(fname), "/tmp/%s_%d.%d.prs", name, v, i);
40                 } else {
41                         slprintf(fname,sizeof(fname), "/tmp/%s.%d.prs", name, i);
42                 }
43                 fd = open(fname, O_WRONLY|O_CREAT|O_EXCL, 0644);
44                 if (fd != -1 || errno != EEXIST) break;
45         }
46         if (fd != -1) {
47                 write(fd, ps->data_p + ps->data_offset, ps->buffer_size - ps->data_offset);
48                 close(fd);
49                 DEBUG(0,("created %s\n", fname));
50         }
51 }
52
53
54
55 /*******************************************************************
56  debug output for parsing info.
57
58  XXXX side-effect of this function is to increase the debug depth XXXX
59
60  ********************************************************************/
61 void prs_debug(prs_struct *ps, int depth, char *desc, char *fn_name)
62 {
63         DEBUG(5+depth, ("%s%06x %s %s\n", tab_depth(depth), ps->data_offset, fn_name, desc));
64 }
65
66
67 /*******************************************************************
68  Initialise a parse structure - malloc the data if requested.
69  ********************************************************************/
70 BOOL prs_init(prs_struct *ps, uint32 size, uint8 align, TALLOC_CTX *ctx, BOOL io)
71 {
72         ZERO_STRUCTP(ps);
73         ps->io = io;
74         ps->bigendian_data = False;
75         ps->align = align;
76         ps->is_dynamic = False;
77         ps->data_offset = 0;
78         ps->buffer_size = 0;
79         ps->data_p = NULL;
80         ps->mem_ctx = ctx;
81
82         if (size != 0) {
83                 ps->buffer_size = size;
84                 if((ps->data_p = (char *)malloc((size_t)size)) == NULL) {
85                         DEBUG(0,("prs_init: malloc fail for %u bytes.\n", (unsigned int)size));
86                         return False;
87                 }
88                 ps->is_dynamic = True; /* We own this memory. */
89         }
90
91         return True;
92 }
93
94 /*******************************************************************
95  read from a socket into memory.
96  ********************************************************************/
97 BOOL prs_read(prs_struct *ps, int fd, size_t len, int timeout)
98 {
99         BOOL ok;
100         size_t prev_size = ps->buffer_size;
101         if (!prs_grow(ps, len))
102                 return False;
103
104         if (timeout > 0) {
105                 ok = (read_with_timeout(fd, &ps->data_p[prev_size],
106                                             len, len,timeout) == len);
107         } else {
108                 ok = (read_data(fd, &ps->data_p[prev_size], len) == len);
109         }
110         return ok;
111 }
112
113 /*******************************************************************
114  Delete the memory in a parse structure - if we own it.
115  ********************************************************************/
116
117 void prs_mem_free(prs_struct *ps)
118 {
119         if(ps->is_dynamic && (ps->data_p != NULL))
120                 free(ps->data_p);
121         ps->is_dynamic = False;
122         ps->data_p = NULL;
123         ps->buffer_size = 0;
124         ps->data_offset = 0;
125 }
126
127 /*******************************************************************
128  Allocate memory when unmarshalling... Always zero clears.
129  ********************************************************************/
130
131 char *prs_alloc_mem(prs_struct *ps, size_t size)
132 {
133         char *ret = talloc(ps->mem_ctx, size);
134
135         if (ret)
136                 memset(ret, '\0', size);
137
138         return ret;
139 }
140
141 /*******************************************************************
142  Return the current talloc context we're using.
143  ********************************************************************/
144
145 TALLOC_CTX *prs_get_mem_context(prs_struct *ps)
146 {
147         return ps->mem_ctx;
148 }
149
150 /*******************************************************************
151  Hand some already allocated memory to a prs_struct.
152  ********************************************************************/
153
154 void prs_give_memory(prs_struct *ps, char *buf, uint32 size, BOOL is_dynamic)
155 {
156         ps->is_dynamic = is_dynamic;
157         ps->data_p = buf;
158         ps->buffer_size = size;
159 }
160
161 /*******************************************************************
162  Take some memory back from a prs_struct.
163  ********************************************************************/
164
165 char *prs_take_memory(prs_struct *ps, uint32 *psize)
166 {
167         char *ret = ps->data_p;
168         if(psize)
169                 *psize = ps->buffer_size;
170         ps->is_dynamic = False;
171         prs_mem_free(ps);
172         return ret;
173 }
174
175 /*******************************************************************
176  Set a prs_struct to exactly a given size. Will grow or tuncate if neccessary.
177  ********************************************************************/
178
179 BOOL prs_set_buffer_size(prs_struct *ps, uint32 newsize)
180 {
181         if (newsize > ps->buffer_size)
182                 return prs_force_grow(ps, newsize - ps->buffer_size);
183
184         if (newsize < ps->buffer_size) {
185                 char *new_data_p = Realloc(ps->data_p, newsize);
186                 /* if newsize is zero, Realloc acts like free() & returns NULL*/
187                 if (new_data_p == NULL && newsize != 0) {
188                         DEBUG(0,("prs_set_buffer_size: Realloc failure for size %u.\n",
189                                 (unsigned int)newsize));
190                         DEBUG(0,("prs_set_buffer_size: Reason %s\n",strerror(errno)));
191                         return False;
192                 }
193                 ps->data_p = new_data_p;
194                 ps->buffer_size = newsize;
195         }
196
197         return True;
198 }
199
200 /*******************************************************************
201  Attempt, if needed, to grow a data buffer.
202  Also depends on the data stream mode (io).
203  ********************************************************************/
204
205 BOOL prs_grow(prs_struct *ps, uint32 extra_space)
206 {
207         uint32 new_size;
208         char *new_data;
209
210         ps->grow_size = MAX(ps->grow_size, ps->data_offset + extra_space);
211
212         if(ps->data_offset + extra_space <= ps->buffer_size)
213                 return True;
214
215         /*
216          * We cannot grow the buffer if we're not reading
217          * into the prs_struct, or if we don't own the memory.
218          */
219
220         if(UNMARSHALLING(ps) || !ps->is_dynamic) {
221                 DEBUG(0,("prs_grow: Buffer overflow - unable to expand buffer by %u bytes.\n",
222                                 (unsigned int)extra_space));
223                 return False;
224         }
225         
226         /*
227          * Decide how much extra space we really need.
228          */
229
230         extra_space -= (ps->buffer_size - ps->data_offset);
231         if(ps->buffer_size == 0) {
232                 /*
233                  * Ensure we have at least a PDU's length, or extra_space, whichever
234                  * is greater.
235                  */
236
237                 new_size = MAX(MAX_PDU_FRAG_LEN,extra_space);
238
239                 if((new_data = malloc(new_size)) == NULL) {
240                         DEBUG(0,("prs_grow: Malloc failure for size %u.\n", (unsigned int)new_size));
241                         return False;
242                 }
243                 memset(new_data, '\0', new_size );
244         } else {
245                 /*
246                  * If the current buffer size is bigger than the space needed, just 
247                  * double it, else add extra_space.
248                  */
249                 new_size = MAX(ps->buffer_size*2, ps->buffer_size + extra_space);               
250
251                 if ((new_data = Realloc(ps->data_p, new_size)) == NULL) {
252                         DEBUG(0,("prs_grow: Realloc failure for size %u.\n",
253                                 (unsigned int)new_size));
254                         return False;
255                 }
256
257                 memset(&new_data[ps->buffer_size], '\0', new_size - ps->buffer_size);
258         }
259         ps->buffer_size = new_size;
260         ps->data_p = new_data;
261
262         return True;
263 }
264
265 /*******************************************************************
266  Attempt to force a data buffer to grow by len bytes.
267  This is only used when appending more data onto a prs_struct
268  when reading an rpc reply, before unmarshalling it.
269  ********************************************************************/
270
271 BOOL prs_force_grow(prs_struct *ps, uint32 extra_space)
272 {
273         uint32 new_size = ps->buffer_size + extra_space;
274         char *new_data;
275
276         if(!UNMARSHALLING(ps) || !ps->is_dynamic) {
277                 DEBUG(0,("prs_force_grow: Buffer overflow - unable to expand buffer by %u bytes.\n",
278                                 (unsigned int)extra_space));
279                 return False;
280         }
281
282         if((new_data = Realloc(ps->data_p, new_size)) == NULL) {
283                 DEBUG(0,("prs_force_grow: Realloc failure for size %u.\n",
284                         (unsigned int)new_size));
285                 return False;
286         }
287
288         memset(&new_data[ps->buffer_size], '\0', new_size - ps->buffer_size);
289
290         ps->buffer_size = new_size;
291         ps->data_p = new_data;
292
293         return True;
294 }
295
296 /*******************************************************************
297  Get the data pointer (external interface).
298  ********************************************************************/
299
300 char *prs_data_p(prs_struct *ps)
301 {
302         return ps->data_p;
303 }
304
305 /*******************************************************************
306  Get the current data size (external interface).
307  ********************************************************************/
308
309 uint32 prs_data_size(prs_struct *ps)
310 {
311         return ps->buffer_size;
312 }
313
314 /*******************************************************************
315  Fetch the current offset (external interface).
316  ********************************************************************/
317
318 uint32 prs_offset(prs_struct *ps)
319 {
320         return ps->data_offset;
321 }
322
323 /*******************************************************************
324  Set the current offset (external interface).
325  ********************************************************************/
326
327 BOOL prs_set_offset(prs_struct *ps, uint32 offset)
328 {
329         if(offset <= ps->data_offset) {
330                 ps->data_offset = offset;
331                 return True;
332         }
333
334         if(!prs_grow(ps, offset - ps->data_offset))
335                 return False;
336
337         ps->data_offset = offset;
338         return True;
339 }
340
341 /*******************************************************************
342  Append the data from one parse_struct into another.
343  ********************************************************************/
344
345 BOOL prs_append_prs_data(prs_struct *dst, prs_struct *src)
346 {
347         if(!prs_grow(dst, prs_offset(src)))
348                 return False;
349
350         memcpy(&dst->data_p[dst->data_offset], prs_data_p(src), (size_t)prs_offset(src));
351         dst->data_offset += prs_offset(src);
352
353         return True;
354 }
355
356 /*******************************************************************
357  Append some data from one parse_struct into another.
358  ********************************************************************/
359
360 BOOL prs_append_some_prs_data(prs_struct *dst, prs_struct *src, int32 start, uint32 len)
361 {       
362         if (len == 0)
363                 return True;
364
365         if(!prs_grow(dst, len))
366                 return False;
367         
368         memcpy(&dst->data_p[dst->data_offset], prs_data_p(src)+start, (size_t)len);
369         dst->data_offset += len;
370
371         return True;
372 }
373
374 /*******************************************************************
375  Append the data from a buffer into a parse_struct.
376  ********************************************************************/
377
378 BOOL prs_append_data(prs_struct *dst, char *src, uint32 len)
379 {
380         if(!prs_grow(dst, len))
381                 return False;
382
383         memcpy(&dst->data_p[dst->data_offset], src, (size_t)len);
384         dst->data_offset += len;
385
386         return True;
387 }
388
389 /*******************************************************************
390  Set the data as big-endian (external interface).
391  ********************************************************************/
392
393 void prs_set_bigendian_data(prs_struct *ps)
394 {
395         ps->bigendian_data = True;
396 }
397
398 /*******************************************************************
399  Align a the data_len to a multiple of align bytes - filling with
400  zeros.
401  ********************************************************************/
402
403 BOOL prs_align(prs_struct *ps)
404 {
405         uint32 mod = ps->data_offset & (ps->align-1);
406
407         if (ps->align != 0 && mod != 0) {
408                 uint32 extra_space = (ps->align - mod);
409                 if(!prs_grow(ps, extra_space))
410                         return False;
411                 memset(&ps->data_p[ps->data_offset], '\0', (size_t)extra_space);
412                 ps->data_offset += extra_space;
413         }
414
415         return True;
416 }
417
418 /*******************************************************************
419  Align only if required (for the unistr2 string mainly)
420  ********************************************************************/
421
422 BOOL prs_align_needed(prs_struct *ps, uint32 needed)
423 {
424         if (needed==0)
425                 return True;
426         else
427                 return prs_align(ps);
428 }
429
430 /*******************************************************************
431  Ensure we can read/write to a given offset.
432  ********************************************************************/
433
434 char *prs_mem_get(prs_struct *ps, uint32 extra_size)
435 {
436         if(UNMARSHALLING(ps)) {
437                 /*
438                  * If reading, ensure that we can read the requested size item.
439                  */
440                 if (ps->data_offset + extra_size > ps->buffer_size) {
441                         DEBUG(0,("prs_mem_get: reading data of size %u would overrun buffer.\n",
442                                         (unsigned int)extra_size ));
443                         return NULL;
444                 }
445         } else {
446                 /*
447                  * Writing - grow the buffer if needed.
448                  */
449                 if(!prs_grow(ps, extra_size))
450                         return NULL;
451         }
452         return &ps->data_p[ps->data_offset];
453 }
454
455 /*******************************************************************
456  Change the struct type.
457  ********************************************************************/
458
459 void prs_switch_type(prs_struct *ps, BOOL io)
460 {
461         if ((ps->io ^ io) == True)
462                 ps->io=io;
463 }
464
465 /*******************************************************************
466  Force a prs_struct to be dynamic even when it's size is 0.
467  ********************************************************************/
468
469 void prs_force_dynamic(prs_struct *ps)
470 {
471         ps->is_dynamic=True;
472 }
473
474 /*******************************************************************
475  Stream a uint8.
476  ********************************************************************/
477
478 BOOL prs_uint8(char *name, prs_struct *ps, int depth, uint8 *data8)
479 {
480         char *q = prs_mem_get(ps, sizeof(uint8));
481         if (q == NULL)
482                 return False;
483
484         DBG_RW_CVAL(name, depth, ps->data_offset, ps->io, q, *data8)
485         ps->data_offset += sizeof(uint8);
486
487         return True;
488 }
489
490 /*******************************************************************
491  Stream a uint16.
492  ********************************************************************/
493
494 BOOL prs_uint16(char *name, prs_struct *ps, int depth, uint16 *data16)
495 {
496         char *q = prs_mem_get(ps, sizeof(uint16));
497         if (q == NULL)
498                 return False;
499
500         DBG_RW_SVAL(name, depth, ps->data_offset, ps->io, ps->bigendian_data, q, *data16)
501         ps->data_offset += sizeof(uint16);
502
503         return True;
504 }
505
506 /*******************************************************************
507  Stream a uint32.
508  ********************************************************************/
509
510 BOOL prs_uint32(char *name, prs_struct *ps, int depth, uint32 *data32)
511 {
512         char *q = prs_mem_get(ps, sizeof(uint32));
513         if (q == NULL)
514                 return False;
515
516         DBG_RW_IVAL(name, depth, ps->data_offset, ps->io, ps->bigendian_data, q, *data32)
517         ps->data_offset += sizeof(uint32);
518
519         return True;
520 }
521
522 /******************************************************************
523  Stream an array of uint8s. Length is number of uint8s.
524  ********************************************************************/
525
526 BOOL prs_uint8s(BOOL charmode, char *name, prs_struct *ps, int depth, uint8 *data8s, int len)
527 {
528         char *q = prs_mem_get(ps, len * sizeof(uint8));
529         if (q == NULL)
530                 return False;
531
532         DBG_RW_PCVAL(charmode, name, depth, ps->data_offset, ps->io, q, data8s, len)
533         ps->data_offset += (len * sizeof(uint8));
534
535         return True;
536 }
537
538 /******************************************************************
539  Stream an array of uint16s. Length is number of uint16s.
540  ********************************************************************/
541
542 BOOL prs_uint16s(BOOL charmode, char *name, prs_struct *ps, int depth, uint16 *data16s, int len)
543 {
544         char *q = prs_mem_get(ps, len * sizeof(uint16));
545         if (q == NULL)
546                 return False;
547
548         DBG_RW_PSVAL(charmode, name, depth, ps->data_offset, ps->io, ps->bigendian_data, q, data16s, len)
549         ps->data_offset += (len * sizeof(uint16));
550
551         return True;
552 }
553
554 /******************************************************************
555  Stream an array of uint32s. Length is number of uint32s.
556  ********************************************************************/
557
558 BOOL prs_uint32s(BOOL charmode, char *name, prs_struct *ps, int depth, uint32 *data32s, int len)
559 {
560         char *q = prs_mem_get(ps, len * sizeof(uint32));
561         if (q == NULL)
562                 return False;
563
564         DBG_RW_PIVAL(charmode, name, depth, ps->data_offset, ps->io, ps->bigendian_data, q, data32s, len)
565         ps->data_offset += (len * sizeof(uint32));
566
567         return True;
568 }
569
570 /******************************************************************
571  Stream an array of unicode string, length/buffer specified separately,
572  in uint16 chars. We use DBG_RW_PCVAL, not DBG_RW_PSVAL here
573  as the unicode string is already in little-endian format.
574  ********************************************************************/
575
576 BOOL prs_buffer5(BOOL charmode, char *name, prs_struct *ps, int depth, BUFFER5 *str)
577 {
578         char *p;
579         char *q = prs_mem_get(ps, str->buf_len * sizeof(uint16));
580         if (q == NULL)
581                 return False;
582
583         if (UNMARSHALLING(ps)) {
584                 str->buffer = (uint16 *)prs_alloc_mem(ps,str->buf_len * sizeof(uint16));
585                 if (str->buffer == NULL)
586                         return False;
587         }
588
589         /* If the string is empty, we don't have anything to stream */
590         if (str->buf_len==0)
591                 return True;
592
593         p = (char *)str->buffer;
594
595         /* If we're using big-endian, reverse to get little-endian. */
596         if(ps->bigendian_data) {
597                 DBG_RW_PSVAL(charmode, name, depth, ps->data_offset, 
598                              ps->io, ps->bigendian_data, q, p, 
599                              str->buf_len)
600         } else {
601                 DBG_RW_PCVAL(charmode, name, depth, ps->data_offset, 
602                              ps->io, q, p, str->buf_len * sizeof(uint16))
603         }
604         
605         ps->data_offset += (str->buf_len * sizeof(uint16));
606
607         return True;
608 }
609
610 /******************************************************************
611  Stream a "not" unicode string, length/buffer specified separately,
612  in byte chars. String is in little-endian format.
613  ********************************************************************/
614
615 BOOL prs_buffer2(BOOL charmode, char *name, prs_struct *ps, int depth, BUFFER2 *str)
616 {
617         char *p;
618         char *q = prs_mem_get(ps, str->buf_len);
619         if (q == NULL)
620                 return False;
621
622         if (UNMARSHALLING(ps)) {
623                 str->buffer = (uint16 *)prs_alloc_mem(ps,str->buf_len);
624                 if (str->buffer == NULL)
625                         return False;
626         }
627
628         p = (char *)str->buffer;
629
630         /* If we're using big-endian, reverse to get little-endian. */
631         if(ps->bigendian_data)
632                 DBG_RW_PSVAL(charmode, name, depth, ps->data_offset, ps->io, ps->bigendian_data, q, p, str->buf_len/2)
633         else
634                 DBG_RW_PCVAL(charmode, name, depth, ps->data_offset, ps->io, q, p, str->buf_len)
635         ps->data_offset += str->buf_len;
636
637         return True;
638 }
639
640 /******************************************************************
641  Stream a string, length/buffer specified separately,
642  in uint8 chars.
643  ********************************************************************/
644
645 BOOL prs_string2(BOOL charmode, char *name, prs_struct *ps, int depth, STRING2 *str)
646 {
647         char *q = prs_mem_get(ps, str->str_str_len * sizeof(uint8));
648         if (q == NULL)
649                 return False;
650
651         if (UNMARSHALLING(ps)) {
652                 str->buffer = (unsigned char *)prs_alloc_mem(ps,str->str_str_len);
653                 if (str->buffer == NULL)
654                         return False;
655         }
656
657         DBG_RW_PCVAL(charmode, name, depth, ps->data_offset, ps->io, q, str->buffer, str->str_max_len)
658         ps->data_offset += (str->str_str_len * sizeof(uint8));
659
660         return True;
661 }
662
663 /******************************************************************
664  Stream a unicode string, length/buffer specified separately,
665  in uint16 chars. We use DBG_RW_PCVAL, not DBG_RW_PSVAL here
666  as the unicode string is already in little-endian format.
667  ********************************************************************/
668
669 BOOL prs_unistr2(BOOL charmode, char *name, prs_struct *ps, int depth, UNISTR2 *str)
670 {
671         char *p;
672         char *q = prs_mem_get(ps, str->uni_str_len * sizeof(uint16));
673         if (q == NULL)
674                 return False;
675
676         /* If the string is empty, we don't have anything to stream */
677         if (str->uni_str_len==0)
678                 return True;
679
680         if (UNMARSHALLING(ps)) {
681                 str->buffer = (uint16 *)prs_alloc_mem(ps,str->uni_max_len * sizeof(uint16));
682                 if (str->buffer == NULL)
683                         return False;
684         }
685
686         p = (char *)str->buffer;
687
688         /* If we're using big-endian, reverse to get little-endian. */
689         if(ps->bigendian_data) {
690                 DBG_RW_PSVAL(charmode, name, depth, ps->data_offset, 
691                              ps->io, ps->bigendian_data, q, p, 
692                              str->uni_str_len)
693         } else {
694                 DBG_RW_PCVAL(charmode, name, depth, ps->data_offset, 
695                              ps->io, q, p, str->uni_str_len * sizeof(uint16))
696         }
697         
698         ps->data_offset += (str->uni_str_len * sizeof(uint16));
699
700         return True;
701 }
702
703
704
705 /******************************************************************
706  Stream a unicode string, length/buffer specified separately,
707  in uint16 chars. We use DBG_RW_PCVAL, not DBG_RW_PSVAL here
708  as the unicode string is already in little-endian format.
709  ********************************************************************/
710
711 BOOL prs_unistr3(BOOL charmode, char *name, UNISTR3 *str, prs_struct *ps, int depth)
712 {
713         char *p;
714         char *q = prs_mem_get(ps, str->uni_str_len * sizeof(uint16));
715         if (q == NULL)
716                 return False;
717
718         if (UNMARSHALLING(ps)) {
719                 str->str.buffer = (uint16 *)prs_alloc_mem(ps,str->uni_str_len * sizeof(uint16));
720                 if (str->str.buffer == NULL)
721                         return False;
722         }
723
724         p = (char *)str->str.buffer;
725
726         /* If we're using big-endian, reverse to get little-endian. */
727         if(ps->bigendian_data)
728                 DBG_RW_PSVAL(charmode, name, depth, ps->data_offset, ps->io, ps->bigendian_data, q, p, str->uni_str_len)
729         else
730                 DBG_RW_PCVAL(charmode, name, depth, ps->data_offset, ps->io, q, p, str->uni_str_len * sizeof(uint16))
731         ps->data_offset += (str->uni_str_len * sizeof(uint16));
732
733         return True;
734 }
735
736 /*******************************************************************
737  Stream a unicode  null-terminated string. As the string is already
738  in little-endian format then do it as a stream of bytes.
739  ********************************************************************/
740
741 BOOL prs_unistr(char *name, prs_struct *ps, int depth, UNISTR *str)
742 {
743         int len = 0;
744         unsigned char *p = (unsigned char *)str->buffer;
745         uint8 *start;
746         char *q;
747         char zero=0;
748         uint32 max_len;
749         uint16* ptr;
750
751         if (MARSHALLING(ps)) {
752
753                 for(len = 0; str->buffer[len] != 0; len++)
754                         ;
755
756                 q = prs_mem_get(ps, (len+1)*2);
757                 if (q == NULL)
758                         return False;
759
760                 start = (uint8*)q;
761
762                 for(len = 0; str->buffer[len] != 0; len++) 
763                 {
764                         if(ps->bigendian_data) 
765                         {
766                                 RW_SVAL(ps->io, ps->bigendian_data, q, *p, 0);
767                                 p += 2;
768                                 q += 2;
769                         } 
770                         else 
771                         {
772                                 RW_CVAL(ps->io, q, *p, 0);
773                                 p++;
774                                 q++;
775                                 RW_CVAL(ps->io, q, *p, 0);
776                                 p++;
777                                 q++;
778                         }
779                 }
780
781                 /*
782                  * even if the string is 'empty' (only an \0 char)
783                  * at this point the leading \0 hasn't been parsed.
784                  * so parse it now
785                  */
786
787                 RW_CVAL(ps->io, q, zero, 0);
788                 q++;
789                 RW_CVAL(ps->io, q, zero, 0);
790                 q++;
791
792                 len++;
793
794                 dump_data(5+depth, (char *)start, len * 2);
795         }
796         else { /* unmarshalling */
797         
798                 uint32 alloc_len = 0;
799                 q = prs_data_p(ps) + prs_offset(ps);
800
801                 /*
802                  * Work out how much space we need and talloc it.
803                  */
804                 max_len = (ps->buffer_size - ps->data_offset)/sizeof(uint16);
805
806                 /* the test of the value of *ptr helps to catch the circumstance
807                    where we have an emtpty (non-existent) string in the buffer */
808                 for ( ptr = (uint16 *)q; *ptr && (alloc_len <= max_len); alloc_len++)
809                         /* do nothing */ 
810                         ;
811
812                 /* should we allocate anything at all? */
813                 str->buffer = (uint16 *)prs_alloc_mem(ps,alloc_len * sizeof(uint16));
814                 if ((str->buffer == NULL) && (alloc_len > 0))
815                         return False;
816
817                 p = (unsigned char *)str->buffer;
818
819                 len = 0;
820                 /* the (len < alloc_len) test is to prevent us from overwriting
821                    memory that is not ours...if we get that far, we have a non-null
822                    terminated string in the buffer and have messed up somewhere */
823                 while ((len < alloc_len) && (*q != '\0'))
824                 {
825                         if(ps->bigendian_data) 
826                         {
827                                 RW_SVAL(ps->io, ps->bigendian_data, q, *p, 0);
828                                 p += 2;
829                                 q += 2;
830                         } else {
831 #if WORDS_BIGENDIAN
832                                 RW_CVAL(ps->io, q+1, *p, 0);
833                                 p++;
834                                 RW_CVAL(ps->io, q, *p, 0);
835                                 p++;
836                                 q+=2;
837 #else
838                                 RW_CVAL(ps->io, q, *p, 0);
839                                 p++;
840                                 q++;
841                                 RW_CVAL(ps->io, q, *p, 0);
842                                 p++;
843                                 q++;
844 #endif  /* WORDS_BIGENDIAN */
845
846                         }
847
848                         len++;
849                 } 
850                 if (len < alloc_len)
851                 {
852                         /* NULL terminate the UNISTR */
853                         str->buffer[len++] = '\0';
854                 }
855         }
856
857         /* set the offset in the prs_struct; 'len' points to the
858            terminiating NULL in the UNISTR so we need to go one more
859            uint16 */
860         ps->data_offset += (len)*2;
861         
862         return True;
863 }
864
865
866 /*******************************************************************
867  Stream a null-terminated string.  len is strlen, and therefore does
868  not include the null-termination character.
869  ********************************************************************/
870
871 BOOL prs_string(char *name, prs_struct *ps, int depth, char *str, int len, int max_buf_size)
872 {
873         char *q;
874         uint8 *start;
875         int i;
876
877         len = MIN(len, (max_buf_size-1));
878
879         q = prs_mem_get(ps, len+1);
880         if (q == NULL)
881                 return False;
882
883         start = (uint8*)q;
884
885         for(i = 0; i < len; i++) {
886                 RW_CVAL(ps->io, q, str[i],0);
887                 q++;
888         }
889
890         /* The terminating null. */
891         str[i] = '\0';
892
893         if (MARSHALLING(ps)) {
894                 RW_CVAL(ps->io, q, str[i], 0);
895         }
896
897         ps->data_offset += len+1;
898
899         dump_data(5+depth, (char *)start, len);
900
901         return True;
902 }
903
904 /*******************************************************************
905  prs_uint16 wrapper. Call this and it sets up a pointer to where the
906  uint16 should be stored, or gets the size if reading.
907  ********************************************************************/
908
909 BOOL prs_uint16_pre(char *name, prs_struct *ps, int depth, uint16 *data16, uint32 *offset)
910 {
911         *offset = ps->data_offset;
912         if (UNMARSHALLING(ps)) {
913                 /* reading. */
914                 return prs_uint16(name, ps, depth, data16);
915         } else {
916                 char *q = prs_mem_get(ps, sizeof(uint16));
917                 if(q ==NULL)
918                         return False;
919                 ps->data_offset += sizeof(uint16);
920         }
921         return True;
922 }
923
924 /*******************************************************************
925  prs_uint16 wrapper.  call this and it retrospectively stores the size.
926  does nothing on reading, as that is already handled by ...._pre()
927  ********************************************************************/
928
929 BOOL prs_uint16_post(char *name, prs_struct *ps, int depth, uint16 *data16,
930                                 uint32 ptr_uint16, uint32 start_offset)
931 {
932         if (MARSHALLING(ps)) {
933                 /* 
934                  * Writing - temporarily move the offset pointer.
935                  */
936                 uint16 data_size = ps->data_offset - start_offset;
937                 uint32 old_offset = ps->data_offset;
938
939                 ps->data_offset = ptr_uint16;
940                 if(!prs_uint16(name, ps, depth, &data_size)) {
941                         ps->data_offset = old_offset;
942                         return False;
943                 }
944                 ps->data_offset = old_offset;
945         } else {
946                 ps->data_offset = start_offset + (uint32)(*data16);
947         }
948         return True;
949 }
950
951 /*******************************************************************
952  prs_uint32 wrapper. Call this and it sets up a pointer to where the
953  uint32 should be stored, or gets the size if reading.
954  ********************************************************************/
955
956 BOOL prs_uint32_pre(char *name, prs_struct *ps, int depth, uint32 *data32, uint32 *offset)
957 {
958         *offset = ps->data_offset;
959         if (UNMARSHALLING(ps) && (data32 != NULL)) {
960                 /* reading. */
961                 return prs_uint32(name, ps, depth, data32);
962         } else {
963                 ps->data_offset += sizeof(uint32);
964         }
965         return True;
966 }
967
968 /*******************************************************************
969  prs_uint32 wrapper.  call this and it retrospectively stores the size.
970  does nothing on reading, as that is already handled by ...._pre()
971  ********************************************************************/
972
973 BOOL prs_uint32_post(char *name, prs_struct *ps, int depth, uint32 *data32,
974                                 uint32 ptr_uint32, uint32 data_size)
975 {
976         if (MARSHALLING(ps)) {
977                 /* 
978                  * Writing - temporarily move the offset pointer.
979                  */
980                 uint32 old_offset = ps->data_offset;
981                 ps->data_offset = ptr_uint32;
982                 if(!prs_uint32(name, ps, depth, &data_size)) {
983                         ps->data_offset = old_offset;
984                         return False;
985                 }
986                 ps->data_offset = old_offset;
987         }
988         return True;
989 }
990
991 /* useful function to store a structure in rpc wire format */
992 int tdb_prs_store(TDB_CONTEXT *tdb, char *keystr, prs_struct *ps)
993 {
994     TDB_DATA kbuf, dbuf;
995     kbuf.dptr = keystr;
996     kbuf.dsize = strlen(keystr)+1;
997     dbuf.dptr = prs_data_p(ps);
998     dbuf.dsize = prs_offset(ps);
999     return tdb_store(tdb, kbuf, dbuf, TDB_REPLACE);
1000 }
1001
1002 /* useful function to fetch a structure into rpc wire format */
1003 int tdb_prs_fetch(TDB_CONTEXT *tdb, char *keystr, prs_struct *ps, TALLOC_CTX *mem_ctx)
1004 {
1005     TDB_DATA kbuf, dbuf;
1006     kbuf.dptr = keystr;
1007     kbuf.dsize = strlen(keystr)+1;
1008
1009     dbuf = tdb_fetch(tdb, kbuf);
1010     if (!dbuf.dptr) return -1;
1011
1012     ZERO_STRUCTP(ps);
1013     prs_init(ps, 0, 4, mem_ctx, UNMARSHALL);
1014     prs_give_memory(ps, dbuf.dptr, dbuf.dsize, True);
1015
1016     return 0;
1017