3 * Testy, Virtual(-izable) Buffer of guint8*'s
5 * "Testy" -- the buffer gets mad when an attempt is made to access data
6 * beyond the bounds of the buffer. An exception is thrown.
8 * "Virtual" -- the buffer can have its own data, can use a subset of
9 * the data of a backing tvbuff, or can be a composite of
14 * Copyright (c) 2000 by Gilbert Ramirez <gram@alumni.rice.edu>
16 * Wireshark - Network traffic analyzer
17 * By Gerald Combs <gerald@wireshark.org>
18 * Copyright 1998 Gerald Combs
20 * This program is free software; you can redistribute it and/or
21 * modify it under the terms of the GNU General Public License
22 * as published by the Free Software Foundation; either version 2
23 * of the License, or (at your option) any later version.
25 * This program is distributed in the hope that it will be useful,
26 * but WITHOUT ANY WARRANTY; without even the implied warranty of
27 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
28 * GNU General Public License for more details.
30 * You should have received a copy of the GNU General Public License
31 * along with this program; if not, write to the Free Software
32 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
39 #include <epan/ipv6-utils.h>
40 #include <epan/guid-utils.h>
41 #include "exceptions.h"
44 * "testy, virtual(-izable) buffer". They are testy in that they get mad when
45 * an attempt is made to access data beyond the bounds of their array. In that
46 * case, they throw an exception.
48 * They are virtualizable in that new tvbuff's can be made from other tvbuffs,
49 * while only the original tvbuff may have data. That is, the new tvbuff has
54 /** The different types of tvbuff's */
62 /* The backing tvbuff_t */
65 /* The offset/length of 'tvb' to which I'm privy */
74 /* Used for quick testing to see if this
75 * is the tvbuff that a COMPOSITE is
82 typedef void (*tvbuff_free_cb_t)(void*);
84 typedef struct tvbuff {
89 struct tvbuff *ds_tvb; /* data source top-level tvbuff */
91 /* The tvbuffs in which this tvbuff is a member
92 * (that is, a backing tvbuff for a TVBUFF_SUBSET
93 * or a member for a TVB_COMPOSITE) */
96 /* TVBUFF_SUBSET and TVBUFF_COMPOSITE keep track
97 * of the other tvbuff's they use */
100 tvb_comp_t composite;
103 /* We're either a TVBUFF_REAL_DATA or a
104 * TVBUFF_SUBSET that has a backing buffer that
105 * has real_data != NULL, or a TVBUFF_COMPOSITE
106 * which has flattened its data due to a call
109 const guint8 *real_data;
111 /* Length of virtual buffer (and/or real_data). */
114 /* Reported length. */
115 guint reported_length;
117 /* Offset from beginning of first TVBUFF_REAL. */
120 /* Func to call when actually freed */
121 tvbuff_free_cb_t free_cb;
126 /** TVBUFF_REAL_DATA contains a guint8* that points to real data.
127 * The data is allocated and contiguous.
129 * TVBUFF_SUBSET has a backing tvbuff. The TVBUFF_SUBSET is a "window"
130 * through which the program sees only a portion of the backing tvbuff.
132 * TVBUFF_COMPOSITE combines multiple tvbuffs sequentually to produce
133 * a larger byte array.
135 * tvbuff's of any type can be used as the backing-tvbuff of a
136 * TVBUFF_SUBSET or as the member of a TVBUFF_COMPOSITE.
137 * TVBUFF_COMPOSITEs can have member-tvbuffs of different types.
139 * Once a tvbuff is create/initialized/finalized, the tvbuff is read-only.
140 * That is, it cannot point to any other data. A new tvbuff must be created if
141 * you want a tvbuff that points to other data.
145 /** "class" initialization. Called once during execution of program
146 * so that tvbuff.c can initialize its data. */
147 extern void tvbuff_init(void);
149 /** "class" cleanup. Called once during execution of program
150 * so that tvbuff.c can clean up its data. */
151 extern void tvbuff_cleanup(void);
154 /** Returns a pointer to a newly initialized tvbuff. Note that
155 * tvbuff's of types TVBUFF_SUBSET and TVBUFF_COMPOSITE
156 * require further initialization via the appropriate functions */
157 extern tvbuff_t* tvb_new(tvbuff_type);
159 /** Marks a tvbuff for freeing. The guint8* data of a TVBUFF_REAL_DATA
160 * is *never* freed by the tvbuff routines. The tvbuff itself is actually freed
161 * once its usage count drops to 0.
163 * Usage counts increment for any time the tvbuff is
164 * used as a member of another tvbuff, i.e., as the backing buffer for
165 * a TVBUFF_SUBSET or as a member of a TVBUFF_COMPOSITE.
167 * Although you may call tvb_free(), the tvbuff may still be in use
168 * by other tvbuff's (TVBUFF_SUBSET or TVBUFF_COMPOSITE), so it is not
169 * safe, unless you know otherwise, to free your guint8* data. If you
170 * cannot be sure that your TVBUFF_REAL_DATA is not in use by another
171 * tvbuff, register a callback with tvb_set_free_cb(); when your tvbuff
172 * is _really_ freed, then your callback will be called, and at that time
173 * you can free your original data.
175 * The caller can artificially increment/decrement the usage count
176 * with tvbuff_increment_usage_count()/tvbuff_decrement_usage_count().
178 extern void tvb_free(tvbuff_t*);
180 /** Free the tvbuff_t and all tvbuff's created from it. */
181 extern void tvb_free_chain(tvbuff_t*);
183 /** Both return the new usage count, after the increment or decrement */
184 extern guint tvb_increment_usage_count(tvbuff_t*, guint count);
186 /** If a decrement causes the usage count to drop to 0, a the tvbuff
187 * is immediately freed. Be sure you know exactly what you're doing
188 * if you decide to use this function, as another tvbuff could
189 * still have a pointer to the just-freed tvbuff, causing corrupted data
190 * or a segfault in the future */
191 extern guint tvb_decrement_usage_count(tvbuff_t*, guint count);
193 /** Set a callback function to call when a tvbuff is actually freed
194 * (once the usage count drops to 0). One argument is passed to
195 * that callback --- a void* that points to the real data.
196 * Obviously, this only applies to a TVBUFF_REAL_DATA tvbuff. */
197 extern void tvb_set_free_cb(tvbuff_t*, tvbuff_free_cb_t);
200 /** Attach a TVBUFF_REAL_DATA tvbuff to a parent tvbuff. This connection
201 * is used during a tvb_free_chain()... the "child" TVBUFF_REAL_DATA acts
202 * as if is part of the chain-of-creation of the parent tvbuff, although it
203 * isn't. This is useful if you need to take the data from some tvbuff,
204 * run some operation on it, like decryption or decompression, and make a new
205 * tvbuff from it, yet want the new tvbuff to be part of the chain. The reality
206 * is that the new tvbuff *is* part of the "chain of creation", but in a way
207 * that these tvbuff routines is ignorant of. Use this function to make
208 * the tvbuff routines knowledgable of this fact. */
209 extern void tvb_set_child_real_data_tvbuff(tvbuff_t* parent, tvbuff_t* child);
211 /**Sets parameters for TVBUFF_REAL_DATA. Can throw ReportedBoundsError. */
212 extern void tvb_set_real_data(tvbuff_t*, const guint8* data, guint length,
213 gint reported_length);
215 /** Combination of tvb_new() and tvb_set_real_data(). Can throw ReportedBoundsError. */
216 extern tvbuff_t* tvb_new_real_data(const guint8* data, guint length,
217 gint reported_length);
220 /** Define the subset of the backing buffer to use.
222 * 'backing_offset' can be negative, to indicate bytes from
223 * the end of the backing buffer.
225 * 'backing_length' can be 0, although the usefulness of the buffer would
228 * 'backing_length' of -1 means "to the end of the backing buffer"
230 * Will throw BoundsError if 'backing_offset'/'length'
231 * is beyond the bounds of the backing tvbuff.
232 * Can throw ReportedBoundsError. */
233 extern void tvb_set_subset(tvbuff_t* tvb, tvbuff_t* backing,
234 gint backing_offset, gint backing_length, gint reported_length);
236 /** Combination of tvb_new() and tvb_set_subset()
237 * Can throw ReportedBoundsError. */
238 extern tvbuff_t* tvb_new_subset(tvbuff_t* backing,
239 gint backing_offset, gint backing_length, gint reported_length);
242 /** Both tvb_composite_append and tvb_composite_prepend can throw
243 * BoundsError if member_offset/member_length goes beyond bounds of
244 * the 'member' tvbuff. */
246 /** Append to the list of tvbuffs that make up this composite tvbuff */
247 extern void tvb_composite_append(tvbuff_t* tvb, tvbuff_t* member);
249 /** Prepend to the list of tvbuffs that make up this composite tvbuff */
250 extern void tvb_composite_prepend(tvbuff_t* tvb, tvbuff_t* member);
252 /** Helper function that calls tvb_new(TVBUFF_COMPOSITE).
253 * Provided only to maintain symmetry with other constructors */
254 extern tvbuff_t* tvb_new_composite(void);
256 /** Mark a composite tvbuff as initialized. No further appends or prepends
257 * occur, data access can finally happen after this finalization. */
258 extern void tvb_composite_finalize(tvbuff_t* tvb);
261 /* Get total length of buffer */
262 extern guint tvb_length(tvbuff_t*);
264 /** Computes bytes to end of buffer, from offset (which can be negative,
265 * to indicate bytes from end of buffer). Function returns -1 to
266 * indicate that offset is out of bounds. No exception is thrown. */
267 extern gint tvb_length_remaining(tvbuff_t*, gint offset);
269 /** Same as above, but throws an exception if the offset is out of bounds. */
270 extern guint tvb_ensure_length_remaining(tvbuff_t*, gint offset);
272 /* Checks (w/o throwing exception) that the bytes referred to by
273 * 'offset'/'length' actually exist in the buffer */
274 extern gboolean tvb_bytes_exist(tvbuff_t*, gint offset, gint length);
276 /** Checks that the bytes referred to by 'offset'/'length' actually exist
277 * in the buffer, and throws an exception if they aren't. */
278 extern void tvb_ensure_bytes_exist(tvbuff_t *tvb, gint offset, gint length);
280 /* Checks (w/o throwing exception) that offset exists in buffer */
281 extern gboolean tvb_offset_exists(tvbuff_t*, gint offset);
283 /* Get reported length of buffer */
284 extern guint tvb_reported_length(tvbuff_t*);
286 /** Computes bytes of reported packet data to end of buffer, from offset
287 * (which can be negative, to indicate bytes from end of buffer). Function
288 * returns -1 to indicate that offset is out of bounds. No exception is
290 extern gint tvb_reported_length_remaining(tvbuff_t *tvb, gint offset);
292 /** Set the reported length of a tvbuff to a given value; used for protocols
293 whose headers contain an explicit length and where the calling
294 dissector's payload may include padding as well as the packet for
297 Also adjusts the data length. */
298 extern void tvb_set_reported_length(tvbuff_t*, guint);
300 extern int offset_from_real_beginning(tvbuff_t *tvb, int counter);
302 /* Returns the offset from the first byte of real data. */
303 #define TVB_RAW_OFFSET(tvb) \
304 ((tvb->raw_offset==-1)?(tvb->raw_offset = offset_from_real_beginning(tvb, 0)):tvb->raw_offset)
306 /************** START OF ACCESSORS ****************/
307 /* All accessors will throw an exception if appropriate */
309 extern guint8 tvb_get_guint8(tvbuff_t*, gint offset);
311 extern guint16 tvb_get_ntohs(tvbuff_t*, gint offset);
312 extern guint32 tvb_get_ntoh24(tvbuff_t*, gint offset);
313 extern guint32 tvb_get_ntohl(tvbuff_t*, gint offset);
314 extern guint64 tvb_get_ntoh64(tvbuff_t*, gint offset);
315 extern gfloat tvb_get_ntohieee_float(tvbuff_t*, gint offset);
316 extern gdouble tvb_get_ntohieee_double(tvbuff_t*, gint offset);
318 extern guint16 tvb_get_letohs(tvbuff_t*, gint offset);
319 extern guint32 tvb_get_letoh24(tvbuff_t*, gint offset);
320 extern guint32 tvb_get_letohl(tvbuff_t*, gint offset);
321 extern guint64 tvb_get_letoh64(tvbuff_t*, gint offset);
322 extern gfloat tvb_get_letohieee_float(tvbuff_t*, gint offset);
323 extern gdouble tvb_get_letohieee_double(tvbuff_t*, gint offset);
326 * Fetch an IPv4 address, in network byte order.
327 * We do *not* convert it to host byte order; we leave it in
328 * network byte order, as that's what its callers expect. */
329 extern guint32 tvb_get_ipv4(tvbuff_t*, gint offset);
331 /* Fetch an IPv6 address. */
332 extern void tvb_get_ipv6(tvbuff_t*, gint offset, struct e_in6_addr *addr);
335 extern void tvb_get_ntohguid(tvbuff_t *tvb, gint offset, e_guid_t *guid);
336 extern void tvb_get_letohguid(tvbuff_t *tvb, gint offset, e_guid_t *guid);
337 extern void tvb_get_guid(tvbuff_t *tvb, gint offset, e_guid_t *guid, gboolean little_endian);
340 /** Returns target for convenience. Does not suffer from possible
341 * expense of tvb_get_ptr(), since this routine is smart enough
342 * to copy data in chunks if the request range actually exists in
343 * different TVBUFF_REAL_DATA tvbuffs. This function assumes that the
344 * target memory is already allocated; it does not allocate or free the
346 extern guint8* tvb_memcpy(tvbuff_t*, guint8* target, gint offset, gint length);
348 /** It is the user's responsibility to g_free() the memory allocated by
349 * tvb_memdup(). Calls tvb_memcpy() */
350 extern guint8* tvb_memdup(tvbuff_t*, gint offset, gint length);
352 /* Same as above but the buffer returned from this function does not have to
353 * be freed. It will be automatically freed after the packet is dissected.
354 * Buffers allocated by this function are NOT persistent.
356 extern guint8* ep_tvb_memdup(tvbuff_t *tvb, gint offset, gint length);
358 /** WARNING! This function is possibly expensive, temporarily allocating
359 * another copy of the packet data. Furthermore, it's dangerous because once
360 * this pointer is given to the user, there's no guarantee that the user will
361 * honor the 'length' and not overstep the boundaries of the buffer.
363 * The returned pointer is data that is internal to the tvbuff, so do not
364 * attempt to free it. Don't modify the data, either, because another tvbuff
365 * that might be using this tvbuff may have already copied that portion of
366 * the data (sometimes tvbuff's need to make copies of data, but that's the
367 * internal implementation that you need not worry about). Assume that the
368 * guint8* points to read-only data that the tvbuff manages.
370 * Return a pointer into our buffer if the data asked for via 'offset'/'length'
371 * is contiguous (which might not be the case for TVBUFF_COMPOSITE). If the
372 * data is not contiguous, a tvb_memdup() is called for the entire buffer
373 * and the pointer to the newly-contiguous data is returned. This dynamically-
374 * allocated memory will be freed when the tvbuff is freed, after the
375 * tvbuff_free_cb_t() is called, if any. */
376 extern const guint8* tvb_get_ptr(tvbuff_t*, gint offset, gint length);
378 /** Find first occurence of any of the needles in tvbuff, starting at offset.
379 * Searches at most maxlength number of bytes; if maxlength is -1, searches
381 * Returns the offset of the found needle, or -1 if not found.
382 * Will not throw an exception, even if maxlength exceeds boundary of tvbuff;
383 * in that case, -1 will be returned if the boundary is reached before
385 extern gint tvb_find_guint8(tvbuff_t*, gint offset, gint maxlength,
388 /** Find first occurence of any of the needles in tvbuff, starting at offset.
389 * Searches at most maxlength number of bytes. Returns the offset of the
390 * found needle, or -1 if not found. Will not throw an exception, even if
391 * maxlength exceeds boundary of tvbuff; in that case, -1 will be returned if
392 * the boundary is reached before finding needle. */
393 extern gint tvb_pbrk_guint8(tvbuff_t *, gint offset, gint maxlength,
396 /** Find size of stringz (NUL-terminated string) by looking for terminating
397 * NUL. The size of the string includes the terminating NUL.
399 * If the NUL isn't found, it throws the appropriate exception.
401 extern guint tvb_strsize(tvbuff_t *tvb, gint offset);
403 /** Find length of string by looking for end of zero terminated string, up to
404 * 'maxlength' characters'; if 'maxlength' is -1, searches to end
406 * Returns -1 if 'maxlength' reached before finding EOS. */
407 extern gint tvb_strnlen(tvbuff_t*, gint offset, guint maxlength);
409 /** Convert a string from Unicode to ASCII. At the moment we fake it by
410 * assuming all characters are ASCII )-: The len parameter is the number
411 * of guint16's to convert from Unicode.
413 * tvb_fake_unicode() returns a buffer allocated by g_malloc() and must
414 * be g_free() by the caller.
415 * tvb_get_ephemeral_faked_unicode() returns a buffer that does not need
416 * to be explicitely freed. Instead this buffer is
417 * automatically freed when wireshark starts dissecting
420 extern char *tvb_fake_unicode(tvbuff_t *tvb, int offset, int len,
421 gboolean little_endian);
422 extern char *tvb_get_ephemeral_faked_unicode(tvbuff_t *tvb, int offset, int len,
423 gboolean little_endian);
426 * Format the data in the tvb from offset for size ...
428 extern gchar * tvb_format_text(tvbuff_t *tvb, gint offset, gint size);
431 * Like "tvb_format_text()", but for null-padded strings; don't show
432 * the null padding characters as "\000".
434 extern gchar *tvb_format_stringzpad(tvbuff_t *tvb, gint offset, gint size);
438 * Given a tvbuff, an offset, and a length, allocate a buffer big enough
439 * to hold a non-null-terminated string of that length at that offset,
440 * plus a trailing zero, copy the string into it, and return a pointer
443 * Throws an exception if the tvbuff ends before the string does.
445 * tvb_get_string() returns a string allocated by g_malloc() and therefore
446 * MUST be g_free() by the caller in order not to leak
449 * tvb_get_ephemeral_string() returns a string that does not need to be freed,
450 * instead it will automatically be freed once the next
451 * packet is dissected.
453 extern guint8 *tvb_get_string(tvbuff_t *tvb, gint offset, gint length);
454 extern guint8 *tvb_get_ephemeral_string(tvbuff_t *tvb, gint offset, gint length);
458 * Given a tvbuff and an offset, with the offset assumed to refer to
459 * a null-terminated string, find the length of that string (and throw
460 * an exception if the tvbuff ends before we find the null), allocate
461 * a buffer big enough to hold the string, copy the string into it,
462 * and return a pointer to the string. Also return the length of the
463 * string (including the terminating null) through a pointer.
465 * tvb_get_stringz() returns a string allocated by g_malloc() and therefore
466 * MUST be g_free() by the caller in order not to leak
469 * tvb_get_ephemeral_stringz() returns a string that does not need to be freed,
470 * instead it will automatically be freed once the next
471 * packet is dissected.
473 extern guint8 *tvb_get_stringz(tvbuff_t *tvb, gint offset, gint *lengthp);
474 extern guint8 *tvb_get_ephemeral_stringz(tvbuff_t *tvb, gint offset, gint *lengthp);
476 /** Looks for a stringz (NUL-terminated string) in tvbuff and copies
477 * no more than bufsize number of bytes, including terminating NUL, to buffer.
478 * Returns length of string (not including terminating NUL), or -1 if the string was
479 * truncated in the buffer due to not having reached the terminating NUL.
480 * In this way, it acts like g_snprintf().
482 * When processing a packet where the remaining number of bytes is less
483 * than bufsize, an exception is not thrown if the end of the packet
484 * is reached before the NUL is found. If no NUL is found before reaching
485 * the end of the short packet, -1 is still returned, and the string
486 * is truncated with a NUL, albeit not at buffer[bufsize - 1], but
487 * at the correct spot, terminating the string.
489 extern gint tvb_get_nstringz(tvbuff_t *tvb, gint offset, guint bufsize,
492 /** Like tvb_get_nstringz(), but never returns -1. The string is guaranteed to
493 * have a terminating NUL. If the string was truncated when copied into buffer,
494 * a NUL is placed at the end of buffer to terminate it.
496 * bufsize MUST be greater than 0.
498 extern gint tvb_get_nstringz0(tvbuff_t *tvb, gint offset, guint bufsize,
502 * Given a tvbuff, an offset into the tvbuff, and a length that starts
503 * at that offset (which may be -1 for "all the way to the end of the
504 * tvbuff"), find the end of the (putative) line that starts at the
505 * specified offset in the tvbuff, going no further than the specified
508 * Return the length of the line (not counting the line terminator at
509 * the end), or, if we don't find a line terminator:
511 * if "deseg" is true, return -1;
513 * if "deseg" is false, return the amount of data remaining in
516 * Set "*next_offset" to the offset of the character past the line
517 * terminator, or past the end of the buffer if we don't find a line
518 * terminator. (It's not set if we return -1.)
520 extern gint tvb_find_line_end(tvbuff_t *tvb, gint offset, int len,
521 gint *next_offset, gboolean desegment);
524 * Given a tvbuff, an offset into the tvbuff, and a length that starts
525 * at that offset (which may be -1 for "all the way to the end of the
526 * tvbuff"), find the end of the (putative) line that starts at the
527 * specified offset in the tvbuff, going no further than the specified
530 * However, treat quoted strings inside the buffer specially - don't
531 * treat newlines in quoted strings as line terminators.
533 * Return the length of the line (not counting the line terminator at
534 * the end), or the amount of data remaining in the buffer if we don't
535 * find a line terminator.
537 * Set "*next_offset" to the offset of the character past the line
538 * terminator, or past the end of the buffer if we don't find a line
541 extern gint tvb_find_line_end_unquoted(tvbuff_t *tvb, gint offset, int len,
545 * Call strncmp after checking if enough chars left, returning 0 if
546 * it returns 0 (meaning "equal") and -1 otherwise, otherwise return -1.
548 extern gint tvb_strneql(tvbuff_t *tvb, gint offset, const gchar *str,
552 * Call strncasecmp after checking if enough chars left, returning 0 if
553 * it returns 0 (meaning "equal") and -1 otherwise, otherwise return -1.
555 extern gint tvb_strncaseeql(tvbuff_t *tvb, gint offset, const gchar *str,
559 * Call memcmp after checking if enough chars left, returning 0 if
560 * it returns 0 (meaning "equal") and -1 otherwise, otherwise return -1.
562 extern gint tvb_memeql(tvbuff_t *tvb, gint offset, const guint8 *str,
566 * Format a bunch of data from a tvbuff as bytes, returning a pointer
567 * to the string with the formatted data, with "punct" as a byte
570 extern gchar *tvb_bytes_to_str_punct(tvbuff_t *tvb, gint offset, gint len,
574 * Format a bunch of data from a tvbuff as bytes, returning a pointer
575 * to the string with the formatted data.
577 extern gchar *tvb_bytes_to_str(tvbuff_t *tvb, gint offset, gint len);
579 #define TVB_GET_DS_TVB(tvb) \
582 /** Locate a sub-tvbuff within another tvbuff, starting at position
583 * 'haystack_offset'. Returns the index of the beginning of 'needle' within
584 * 'haystack', or -1 if 'needle' is not found. The index is relative
585 * to the start of 'haystack', not 'haystack_offset'. */
586 extern gint tvb_find_tvb(tvbuff_t *haystack_tvb, tvbuff_t *needle_tvb,
587 gint haystack_offset);
590 * Uncompresses a zlib compressed packet inside a tvbuff at offset with
591 * length comprlen. Returns an uncompressed tvbuffer if uncompression
592 * succeeded or NULL if uncompression failed.
594 extern tvbuff_t* tvb_uncompress(tvbuff_t *tvb, int offset, int comprlen);
596 /************** END OF ACCESSORS ****************/
598 #endif /* __TVBUFF_H__ */