path: root/epan/tvbuff.c

/* tvbuff.c
 *
 * Testy, Virtual(-izable) Buffer of guint8*'s
 *
 * "Testy" -- the buffer gets mad when an attempt to access data
 *		beyond the bounds of the buffer. An exception is thrown.
 *
 * "Virtual" -- the buffer can have its own data, can use a subset of
 *		the data of a backing tvbuff, or can be a composite of
 *		other tvbuffs.
 *
 * $Id$
 *
 * Copyright (c) 2000 by Gilbert Ramirez <gram@alumni.rice.edu>
 *
 * Code to convert IEEE floating point formats to native floating point
 * derived from code Copyright (c) Ashok Narayanan, 2000
 *
 * Wireshark - Network traffic analyzer
 * By Gerald Combs <gerald@wireshark.org>
 * Copyright 1998 Gerald Combs
 *
 * 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

#include "config.h"

#include <string.h>

#ifdef HAVE_LIBZ
#include <zlib.h>
#endif

#include "pint.h"
#include "tvbuff.h"
#include "tvbuff-int.h"
#include "strutil.h"
#include "emem.h"
#include "charsets.h"
#include "proto.h"	/* XXX - only used for DISSECTOR_ASSERT, probably a new header file? */

static const guint8*
ensure_contiguous_no_exception(tvbuff_t *tvb, const gint offset, const gint length,
		int *exception);

static const guint8*
ensure_contiguous(tvbuff_t *tvb, const gint offset, const gint length);


static guint64
_tvb_get_bits64(tvbuff_t *tvb, guint bit_offset, const gint total_no_of_bits);

static void
tvb_init(tvbuff_t *tvb, const tvbuff_type type)
{
	tvb_backing_t	*backing;
	tvb_comp_t	*composite;

	tvb->previous	     = NULL;
	tvb->next	     = NULL;
	tvb->type	     = type;
	tvb->initialized     = FALSE;
	tvb->length	     = 0;
	tvb->reported_length = 0;
	tvb->free_cb	     = NULL;
	tvb->real_data	     = NULL;
	tvb->raw_offset	     = -1;
	tvb->ds_tvb	     = NULL;

	switch(type) {
		case TVBUFF_REAL_DATA:
			/* Nothing */
			break;

		case TVBUFF_SUBSET:
			backing 	= &tvb->tvbuffs.subset;
			backing->tvb	= NULL;
			backing->offset	= 0;
			backing->length	= 0;
			break;

		case TVBUFF_COMPOSITE:
			composite 		 = &tvb->tvbuffs.composite;
			composite->tvbs		 = NULL;
			composite->start_offsets = NULL;
			composite->end_offsets	 = NULL;
			break;

		default:
			DISSECTOR_ASSERT_NOT_REACHED();
			break;
	}
}

static tvbuff_t *
tvb_new(const tvbuff_type type)
{
	tvbuff_t *tvb;

	tvb = g_slice_new(tvbuff_t);

	tvb_init(tvb, type);

	return tvb;
}

static void
tvb_free_internal(tvbuff_t *tvb)
{
	tvb_comp_t	*composite;

	DISSECTOR_ASSERT(tvb);

	switch (tvb->type) {
		case TVBUFF_REAL_DATA:
			if (tvb->free_cb) {
				/*
				 * XXX - do this with a union?
				 */
				tvb->free_cb((gpointer)tvb->real_data);
			}
			break;

		case TVBUFF_SUBSET:
			/* Nothing */
			break;

		case TVBUFF_COMPOSITE:
			composite = &tvb->tvbuffs.composite;

			g_slist_free(composite->tvbs);

			g_free(composite->start_offsets);
			g_free(composite->end_offsets);
			if (tvb->real_data) {
				/*
				 * XXX - do this with a union?
				 */
				g_free((gpointer)tvb->real_data);
			}
			break;

		default:
			DISSECTOR_ASSERT_NOT_REACHED();
	}

	g_slice_free(tvbuff_t, tvb);
}

/* XXX: just call tvb_free_chain();
 *      Not removed so that existing dissectors using tvb_free() need not be changed.
 *      I'd argue that existing calls to tvb_free() should have actually beeen
 *      calls to tvb_free_chain() although the calls were OK as long as no
 *      subsets, etc had been created on the tvb. */
void
tvb_free(tvbuff_t *tvb)
{
	tvb_free_chain(tvb);
}

void
tvb_free_chain(tvbuff_t  *tvb)
{
	tvbuff_t *next_tvb;
	DISSECTOR_ASSERT(tvb);
	DISSECTOR_ASSERT_HINT(tvb->previous==NULL, "tvb_free_chain(): tvb must be initial tvb in chain");
	while (tvb) {
		next_tvb=tvb->next;
		DISSECTOR_ASSERT_HINT((next_tvb==NULL) || (tvb==next_tvb->previous), "tvb_free_chain(): corrupt tvb chain ?");
		tvb_free_internal(tvb);
		tvb  = next_tvb;
	}
}

void
tvb_set_free_cb(tvbuff_t *tvb, const tvbuff_free_cb_t func)
{
	DISSECTOR_ASSERT(tvb);
	DISSECTOR_ASSERT(tvb->type == TVBUFF_REAL_DATA);
	tvb->free_cb = func;
}

static void
add_to_chain(tvbuff_t *parent, tvbuff_t *child)
{
	DISSECTOR_ASSERT(parent && child);
	DISSECTOR_ASSERT(!child->next && !child->previous);
	child->next	= parent->next;
	child->previous = parent;
	if (parent->next)
		parent->next->previous = child;
	parent->next    = child;
}

void
tvb_set_child_real_data_tvbuff(tvbuff_t *parent, tvbuff_t *child)
{
	DISSECTOR_ASSERT(parent && child);
	DISSECTOR_ASSERT(parent->initialized);
	DISSECTOR_ASSERT(child->initialized);
	DISSECTOR_ASSERT(child->type == TVBUFF_REAL_DATA);
	add_to_chain(parent, child);
}

tvbuff_t *
tvb_new_real_data(const guint8* data, const guint length, const gint reported_length)
{
	tvbuff_t *tvb;

	THROW_ON(reported_length < -1, ReportedBoundsError);

	tvb = tvb_new(TVBUFF_REAL_DATA);

	tvb->real_data       = data;
	tvb->length          = length;
	tvb->reported_length = reported_length;
	tvb->initialized     = TRUE;

	/*
	 * This is the top-level real tvbuff for this data source,
	 * so its data source tvbuff is itself.
	 */
	tvb->ds_tvb = tvb;
	return tvb;
}

tvbuff_t *
tvb_new_child_real_data(tvbuff_t *parent, const guint8* data, const guint length, const gint reported_length)
{
	tvbuff_t *tvb = tvb_new_real_data(data, length, reported_length);
	if (tvb) {
		tvb_set_child_real_data_tvbuff (parent, tvb);
	}

	return tvb;
}

/* Computes the absolute offset and length based on a possibly-negative offset
 * and a length that is possible -1 (which means "to the end of the data").
 * Returns TRUE/FALSE indicating whether the offset is in bounds or
 * not. The integer ptrs are modified with the new offset and length.
 * No exception is thrown.
 *
 * XXX - we return TRUE, not FALSE, if the offset is positive and right
 * after the end of the tvbuff (i.e., equal to the length).  We do this
 * so that a dissector constructing a subset tvbuff for the next protocol
 * will get a zero-length tvbuff, not an exception, if there's no data
 * left for the next protocol - we want the next protocol to be the one
 * that gets an exception, so the error is reported as an error in that
 * protocol rather than the containing protocol.  */
static gboolean
compute_offset_length(const tvbuff_t *tvb,
		      const gint offset, const gint length_val,
		      guint *offset_ptr, guint *length_ptr, int *exception)
{
	DISSECTOR_ASSERT(offset_ptr);
	DISSECTOR_ASSERT(length_ptr);

	/* Compute the offset */
	if (offset >= 0) {
		/* Positive offset - relative to the beginning of the packet. */
		if ((guint) offset > tvb->reported_length) {
			if (exception) {
				*exception = ReportedBoundsError;
			}
			return FALSE;
		}
		else if ((guint) offset > tvb->length) {
			if (exception) {
				*exception = BoundsError;
			}
			return FALSE;
		}
		else {
			*offset_ptr = offset;
		}
	}
	else {
		/* Negative offset - relative to the end of the packet. */
		if ((guint) -offset > tvb->reported_length) {
			if (exception) {
				*exception = ReportedBoundsError;
			}
			return FALSE;
		}
		else if ((guint) -offset > tvb->length) {
			if (exception) {
				*exception = BoundsError;
			}
			return FALSE;
		}
		else {
			*offset_ptr = tvb->length + offset;
		}
	}

	/* Compute the length */
	if (length_val < -1) {
		if (exception) {
			/* XXX - ReportedBoundsError? */
			*exception = BoundsError;
		}
		return FALSE;
	}
	else if (length_val == -1) {
		*length_ptr = tvb->length - *offset_ptr;
	}
	else {
		*length_ptr = length_val;
	}

	return TRUE;
}

static gboolean
check_offset_length_no_exception(const tvbuff_t *tvb,
				 const gint offset, gint const length_val,
				 guint *offset_ptr, guint *length_ptr, int *exception)
{
	guint	end_offset;

	if (!compute_offset_length(tvb,
				   offset, length_val, offset_ptr, length_ptr, exception)) {
		return FALSE;
	}

	/*
	 * Compute the offset of the first byte past the length.
	 */
	end_offset = *offset_ptr + *length_ptr;

	/*
	 * Check for an overflow, and clamp "end_offset" at the maximum
	 * if we got an overflow - that should force us to indicate that
	 * we're past the end of the tvbuff.
	 */
	if (end_offset < *offset_ptr)
		end_offset = UINT_MAX;

	/*
	 * Check whether that offset goes more than one byte past the
	 * end of the buffer.
	 *
	 * If not, return TRUE; otherwise, return FALSE and, if "exception"
	 * is non-null, return the appropriate exception through it.
	 */
	if (end_offset <= tvb->length) {
		return TRUE;
	}
	else if (end_offset <= tvb->reported_length) {
		if (exception) {
			*exception = BoundsError;
		}
	}
	else {
		if (exception) {
			*exception = ReportedBoundsError;
		}
	}

	return FALSE;
}

/* Checks (+/-) offset and length and throws an exception if
 * either is out of bounds. Sets integer ptrs to the new offset
 * and length. */
static void
check_offset_length(const tvbuff_t *tvb,
		    const gint offset, gint const length_val,
		    guint *offset_ptr, guint *length_ptr)
{
	int exception = 0;

	if (!check_offset_length_no_exception(tvb,
					      offset, length_val, offset_ptr, length_ptr, &exception)) {
		DISSECTOR_ASSERT(exception > 0);
		THROW(exception);
	}
}

static tvbuff_t *
tvb_new_with_subset(tvbuff_t *backing, const gint reported_length,
    const guint subset_tvb_offset, const guint subset_tvb_length)
{
	tvbuff_t *tvb = tvb_new(TVBUFF_SUBSET);

	tvb->tvbuffs.subset.offset = subset_tvb_offset;
	tvb->tvbuffs.subset.length = subset_tvb_length;

	tvb->tvbuffs.subset.tvb	     = backing;
	tvb->length		     = tvb->tvbuffs.subset.length;

	if (reported_length == -1) {
		tvb->reported_length = backing->reported_length - tvb->tvbuffs.subset.offset;
	}
	else {
		tvb->reported_length = reported_length;
	}
	tvb->initialized	     = TRUE;
	add_to_chain(backing, tvb);

	/* Optimization. If the backing buffer has a pointer to contiguous, real data,
	 * then we can point directly to our starting offset in that buffer */
	if (backing->real_data != NULL) {
		tvb->real_data = backing->real_data + tvb->tvbuffs.subset.offset;
	}

	return tvb;
}

tvbuff_t *
tvb_new_subset(tvbuff_t *backing, const gint backing_offset, const gint backing_length, const gint reported_length)
{
	tvbuff_t *tvb;
	guint	  subset_tvb_offset;
	guint	  subset_tvb_length;

	DISSECTOR_ASSERT(backing && backing->initialized);

	THROW_ON(reported_length < -1, ReportedBoundsError);

	check_offset_length(backing, backing_offset, backing_length,
			    &subset_tvb_offset,
			    &subset_tvb_length);

	tvb = tvb_new_with_subset(backing, reported_length,
	    subset_tvb_offset, subset_tvb_length);

	/*
	 * The top-level data source of this tvbuff is the top-level
	 * data source of its parent.
	 */
	tvb->ds_tvb = backing->ds_tvb;

	return tvb;
}

tvbuff_t *
tvb_new_subset_length(tvbuff_t *backing, const gint backing_offset, const gint backing_length)
{
	gint	  captured_length;
	tvbuff_t *tvb;
	guint	  subset_tvb_offset;
	guint	  subset_tvb_length;

	DISSECTOR_ASSERT(backing && backing->initialized);

	THROW_ON(backing_length < 0, ReportedBoundsError);

	/*
	 * Give the next dissector only captured_length bytes.
	 */
	captured_length = tvb_length_remaining(backing, backing_offset);
	THROW_ON(captured_length < 0, BoundsError);
	if (captured_length > backing_length)
		captured_length = backing_length;

	check_offset_length(backing, backing_offset, captured_length,
			    &subset_tvb_offset,
			    &subset_tvb_length);

	tvb = tvb_new_with_subset(backing, backing_length,
	    subset_tvb_offset, subset_tvb_length);

	/*
	 * The top-level data source of this tvbuff is the top-level
	 * data source of its parent.
	 */
	tvb->ds_tvb = backing->ds_tvb;

	return tvb;
}

tvbuff_t *
tvb_new_subset_remaining(tvbuff_t *backing, const gint backing_offset)
{
	tvbuff_t *tvb;
	guint	  subset_tvb_offset;
	guint	  subset_tvb_length;

	check_offset_length(backing, backing_offset, -1 /* backing_length */,
			    &subset_tvb_offset,
			    &subset_tvb_length);

	tvb = tvb_new_with_subset(backing, -1 /* reported_length */,
	    subset_tvb_offset, subset_tvb_length);

	/*
	 * The top-level data source of this tvbuff is the top-level
	 * data source of its parent.
	 */
	tvb->ds_tvb = backing->ds_tvb;

	return tvb;
}

static const unsigned char left_aligned_bitmask[] = {
	0xff,
	0x80,
	0xc0,
	0xe0,
	0xf0,
	0xf8,
	0xfc,
	0xfe
};

tvbuff_t *
tvb_new_octet_aligned(tvbuff_t *tvb, guint32 bit_offset, gint32 no_of_bits)
{
	tvbuff_t     *sub_tvb = NULL;
	guint32       byte_offset;
	gint32        datalen, i;
	guint8        left, right, remaining_bits, *buf;
	const guint8 *data;

	byte_offset = bit_offset >> 3;
	left = bit_offset % 8; /* for left-shifting */
	right = 8 - left; /* for right-shifting */

	if (no_of_bits == -1) {
		datalen = tvb_length_remaining(tvb, byte_offset);
		remaining_bits = 0;
	} else {
		datalen = no_of_bits >> 3;
		remaining_bits = no_of_bits % 8;
		if (remaining_bits) {
			datalen++;
		}
	}

	/* already aligned -> shortcut */
	if ((left == 0) && (remaining_bits == 0)) {
		return tvb_new_subset(tvb, byte_offset, datalen, -1);
	}

	DISSECTOR_ASSERT(datalen>0);
	buf = ep_alloc0(datalen);

	/* if at least one trailing byte is available, we must use the content
 	* of that byte for the last shift (i.e. tvb_get_ptr() must use datalen + 1
 	* if non extra byte is available, the last shifted byte requires
 	* special treatment
 	*/
	if (tvb_length_remaining(tvb, byte_offset) > datalen) {
		data = tvb_get_ptr(tvb, byte_offset, datalen + 1);
		/* shift tvb data bit_offset bits to the left */
		for (i = 0; i < datalen; i++)
			buf[i] = (data[i] << left) | (data[i+1] >> right);
	} else {
		data = tvb_get_ptr(tvb, byte_offset, datalen);
		/* shift tvb data bit_offset bits to the left */
		for (i = 0; i < (datalen-1); i++)
			buf[i] = (data[i] << left) | (data[i+1] >> right);
		buf[datalen-1] = data[datalen-1] << left; /* set last octet */
	}
	buf[datalen-1] &= left_aligned_bitmask[remaining_bits];

	sub_tvb = tvb_new_child_real_data(tvb, buf, datalen, datalen);

	return sub_tvb;
}

/*
 * Composite tvb
 *
 *   1. A composite tvb is automatically chained to its first member when the
 *      tvb is finalized.
 *      This means that composite tvb members must all be in the same chain.
 *      ToDo: enforce this: By searching the chain?
 */
tvbuff_t *
tvb_new_composite(void)
{
	return tvb_new(TVBUFF_COMPOSITE);
}

void
tvb_composite_append(tvbuff_t *tvb, tvbuff_t *member)
{
	tvb_comp_t *composite;

	DISSECTOR_ASSERT(tvb && !tvb->initialized);
	DISSECTOR_ASSERT(tvb->type == TVBUFF_COMPOSITE);

	/* Don't allow zero-length TVBs: composite_memcpy() can't handle them
	 * and anyway it makes no sense.
	 */
	DISSECTOR_ASSERT(member->length);

	composite       = &tvb->tvbuffs.composite;
	composite->tvbs = g_slist_append(composite->tvbs, member);
}

void
tvb_composite_prepend(tvbuff_t *tvb, tvbuff_t *member)
{
	tvb_comp_t *composite;

	DISSECTOR_ASSERT(tvb && !tvb->initialized);
	DISSECTOR_ASSERT(tvb->type == TVBUFF_COMPOSITE);

	/* Don't allow zero-length TVBs: composite_memcpy() can't handle them
	 * and anyway it makes no sense.
	 */
	DISSECTOR_ASSERT(member->length);

	composite       = &tvb->tvbuffs.composite;
	composite->tvbs = g_slist_prepend(composite->tvbs, member);
}


void
tvb_composite_finalize(tvbuff_t *tvb)
{
	GSList	   *slist;
	guint	    num_members;
	tvbuff_t   *member_tvb;
	tvb_comp_t *composite;
	int	    i = 0;

	DISSECTOR_ASSERT(tvb && !tvb->initialized);
	DISSECTOR_ASSERT(tvb->type == TVBUFF_COMPOSITE);
	DISSECTOR_ASSERT(tvb->length == 0);
	DISSECTOR_ASSERT(tvb->reported_length == 0);

	composite   = &tvb->tvbuffs.composite;
	num_members = g_slist_length(composite->tvbs);

	/* Dissectors should not create composite TVBs if they're not going to
	 * put at least one TVB in them.
	 * (Without this check--or something similar--we'll seg-fault below.)
	 */
	DISSECTOR_ASSERT(num_members);

	composite->start_offsets = g_new(guint, num_members);
	composite->end_offsets = g_new(guint, num_members);

	for (slist = composite->tvbs; slist != NULL; slist = slist->next) {
		DISSECTOR_ASSERT((guint) i < num_members);
		member_tvb = slist->data;
		composite->start_offsets[i] = tvb->length;
		tvb->length += member_tvb->length;
		tvb->reported_length += member_tvb->reported_length;
		composite->end_offsets[i] = tvb->length - 1;
		i++;
	}
	add_to_chain((tvbuff_t *)composite->tvbs->data, tvb); /* chain composite tvb to first member */
	tvb->initialized = TRUE;
}



guint
tvb_length(const tvbuff_t *tvb)
{
	DISSECTOR_ASSERT(tvb && tvb->initialized);

	return tvb->length;
}

gint
tvb_length_remaining(const tvbuff_t *tvb, const gint offset)
{
	guint abs_offset, abs_length;

	DISSECTOR_ASSERT(tvb && tvb->initialized);

	if (compute_offset_length(tvb, offset, -1, &abs_offset, &abs_length, NULL)) {
		return abs_length;
	}
	else {
		return -1;
	}
}

guint
tvb_ensure_length_remaining(const tvbuff_t *tvb, const gint offset)
{
	guint abs_offset, abs_length;
	int   exception;

	DISSECTOR_ASSERT(tvb && tvb->initialized);

	if (!compute_offset_length(tvb, offset, -1, &abs_offset, &abs_length, &exception)) {
		THROW(exception);
	}
	if (abs_length == 0) {
		/*
		 * This routine ensures there's at least one byte available.
		 * There aren't any bytes available, so throw the appropriate
		 * exception.
		 */
		if (abs_offset >= tvb->reported_length)
			THROW(ReportedBoundsError);
		else
			THROW(BoundsError);
	}
	return abs_length;
}




/* Validates that 'length' bytes are available starting from
 * offset (pos/neg). Does not throw an exception. */
gboolean
tvb_bytes_exist(const tvbuff_t *tvb, const gint offset, const gint length)
{
	guint abs_offset, abs_length;

	DISSECTOR_ASSERT(tvb && tvb->initialized);

	if (!compute_offset_length(tvb, offset, length, &abs_offset, &abs_length, NULL))
		return FALSE;

	if (abs_offset + abs_length <= tvb->length) {
		return TRUE;
	}
	else {
		return FALSE;
	}
}

/* Validates that 'length' bytes are available starting from
 * offset (pos/neg). Throws an exception if they aren't. */
void
tvb_ensure_bytes_exist(const tvbuff_t *tvb, const gint offset, const gint length)
{
	guint abs_offset, abs_length;

	DISSECTOR_ASSERT(tvb && tvb->initialized);

	/*
	 * -1 doesn't mean "until end of buffer", as that's pointless
	 * for this routine.  We must treat it as a Really Large Positive
	 * Number, so that we throw an exception; we throw
	 * ReportedBoundsError, as if it were past even the end of a
	 * reassembled packet, and past the end of even the data we
	 * didn't capture.
	 *
	 * We do the same with other negative lengths.
	 */
	if (length < 0) {
		THROW(ReportedBoundsError);
	}
	check_offset_length(tvb, offset, length, &abs_offset, &abs_length);
}

gboolean
tvb_offset_exists(const tvbuff_t *tvb, const gint offset)
{
	guint abs_offset, abs_length;

	DISSECTOR_ASSERT(tvb && tvb->initialized);
	if (!compute_offset_length(tvb, offset, -1, &abs_offset, &abs_length, NULL))
		return FALSE;

	if (abs_offset < tvb->length) {
		return TRUE;
	}
	else {
		return FALSE;
	}
}

guint
tvb_reported_length(const tvbuff_t *tvb)
{
	DISSECTOR_ASSERT(tvb && tvb->initialized);

	return tvb->reported_length;
}

gint
tvb_reported_length_remaining(const tvbuff_t *tvb, const gint offset)
{
	guint abs_offset, abs_length;

	DISSECTOR_ASSERT(tvb && tvb->initialized);

	if (compute_offset_length(tvb, offset, -1, &abs_offset, &abs_length, NULL)) {
		if (tvb->reported_length >= abs_offset)
			return tvb->reported_length - abs_offset;
		else
			return -1;
	}
	else {
		return -1;
	}
}

/* Set the reported length of a tvbuff to a given value; used for protocols
 * whose headers contain an explicit length and where the calling
 * dissector's payload may include padding as well as the packet for
 * this protocol.
 * Also adjusts the data length. */
void
tvb_set_reported_length(tvbuff_t *tvb, const guint reported_length)
{
	DISSECTOR_ASSERT(tvb && tvb->initialized);

	if (reported_length > tvb->reported_length)
		THROW(ReportedBoundsError);

	tvb->reported_length = reported_length;
	if (reported_length < tvb->length)
		tvb->length = reported_length;
}


#if 0
static const guint8*
first_real_data_ptr(tvbuff_t *tvb)
{
	tvbuff_t *member;

	switch(tvb->type) {
		case TVBUFF_REAL_DATA:
			return tvb->real_data;
		case TVBUFF_SUBSET:
			member = tvb->tvbuffs.subset.tvb;
			return first_real_data_ptr(member);
		case TVBUFF_COMPOSITE:
			member = tvb->tvbuffs.composite.tvbs->data;
			return first_real_data_ptr(member);
	}

	DISSECTOR_ASSERT_NOT_REACHED();
	return NULL;
}
#endif

static guint
offset_from_real_beginning(const tvbuff_t *tvb, const guint counter)
{
	tvbuff_t *member;

	switch(tvb->type) {
		case TVBUFF_REAL_DATA:
			return counter;
		case TVBUFF_SUBSET:
			member = tvb->tvbuffs.subset.tvb;
			return offset_from_real_beginning(member, counter + tvb->tvbuffs.subset.offset);
		case TVBUFF_COMPOSITE:
			member = tvb->tvbuffs.composite.tvbs->data;
			return offset_from_real_beginning(member, counter);
	}

	DISSECTOR_ASSERT_NOT_REACHED();
	return 0;
}

guint
tvb_offset_from_real_beginning(const tvbuff_t *tvb)
{
	return offset_from_real_beginning(tvb, 0);
}

static const guint8*
composite_ensure_contiguous_no_exception(tvbuff_t *tvb, const guint abs_offset, const guint abs_length)
{
	guint	    i, num_members;
	tvb_comp_t *composite;
	tvbuff_t   *member_tvb = NULL;
	guint	    member_offset, member_length;
	GSList	   *slist;

	DISSECTOR_ASSERT(tvb->type == TVBUFF_COMPOSITE);

	/* Maybe the range specified by offset/length
	 * is contiguous inside one of the member tvbuffs */
	composite = &tvb->tvbuffs.composite;
	num_members = g_slist_length(composite->tvbs);

	for (i = 0; i < num_members; i++) {
		if (abs_offset <= composite->end_offsets[i]) {
			slist = g_slist_nth(composite->tvbs, i);
			member_tvb = slist->data;
			break;
		}
	}
	DISSECTOR_ASSERT(member_tvb);

	if (check_offset_length_no_exception(member_tvb,
					     abs_offset - composite->start_offsets[i],
					     abs_length, &member_offset, &member_length, NULL)) {

		/*
		 * The range is, in fact, contiguous within member_tvb.
		 */
		DISSECTOR_ASSERT(!tvb->real_data);
		return ensure_contiguous_no_exception(member_tvb, member_offset, member_length, NULL);
	}
	else {
		tvb->real_data = tvb_memdup(tvb, 0, -1);
		return tvb->real_data + abs_offset;
	}

	DISSECTOR_ASSERT_NOT_REACHED();
}

static const guint8*
ensure_contiguous_no_exception(tvbuff_t *tvb, const gint offset, const gint length, int *exception)
{
	guint abs_offset, abs_length;

	if (!check_offset_length_no_exception(tvb, offset, length,
		&abs_offset, &abs_length, exception)) {
		return NULL;
	}

	/*
	 * We know that all the data is present in the tvbuff, so
	 * no exceptions should be thrown.
	 */
	if (tvb->real_data) {
		return tvb->real_data + abs_offset;
	}
	else {
		switch(tvb->type) {
			case TVBUFF_REAL_DATA:
				DISSECTOR_ASSERT_NOT_REACHED();
			case TVBUFF_SUBSET:
				return ensure_contiguous_no_exception(tvb->tvbuffs.subset.tvb,
						abs_offset - tvb->tvbuffs.subset.offset,
						abs_length, NULL);
			case TVBUFF_COMPOSITE:
				return composite_ensure_contiguous_no_exception(tvb, abs_offset, abs_length);
		}
	}

	DISSECTOR_ASSERT_NOT_REACHED();
	return NULL;
}

static const guint8*
ensure_contiguous(tvbuff_t *tvb, const gint offset, const gint length)
{
	int           exception = 0;
	const guint8 *p;

	p = ensure_contiguous_no_exception(tvb, offset, length, &exception);
	if (p == NULL) {
		DISSECTOR_ASSERT(exception > 0);
		THROW(exception);
	}
	return p;
}

static const guint8*
fast_ensure_contiguous(tvbuff_t *tvb, const gint offset, const guint length)
{
	guint end_offset;
	guint u_offset;

	DISSECTOR_ASSERT(tvb && tvb->initialized);
	/* We don't check for overflow in this fast path so we only handle simple types */
	DISSECTOR_ASSERT(length <= 8);

	if (offset < 0 || !tvb->real_data) {
		return ensure_contiguous(tvb, offset, length);
	}

	u_offset = offset;
	end_offset = u_offset + length;

	if (end_offset <= tvb->length) {
		return tvb->real_data + u_offset;
	}

	if (end_offset > tvb->reported_length) {
		THROW(ReportedBoundsError);
	}
	THROW(BoundsError);
	/* not reached */
	return NULL;
}

static const guint8*
guint8_pbrk(const guint8* haystack, size_t haystacklen, const guint8 *needles, guchar *found_needle)
{
	gchar         tmp[256] = { 0 };
	const guint8 *haystack_end;

	while (*needles)
		tmp[*needles++] = 1;

	haystack_end = haystack + haystacklen;
	while (haystack < haystack_end) {
		if (tmp[*haystack]) {
			if (found_needle)
				*found_needle = *haystack;
			return haystack;
		}
		haystack++;
	}

	return NULL;
}



/************** ACCESSORS **************/

static void *
composite_memcpy(tvbuff_t *tvb, guint8* target, guint abs_offset, size_t abs_length)
{
	guint	    i, num_members;
	tvb_comp_t *composite;
	tvbuff_t   *member_tvb = NULL;
	guint	    member_offset, member_length;
	gboolean    retval;
	GSList	   *slist;

	DISSECTOR_ASSERT(tvb->type == TVBUFF_COMPOSITE);

	/* Maybe the range specified by offset/length
	 * is contiguous inside one of the member tvbuffs */
	composite   = &tvb->tvbuffs.composite;
	num_members = g_slist_length(composite->tvbs);

	for (i = 0; i < num_members; i++) {
		if (abs_offset <= composite->end_offsets[i]) {
			slist = g_slist_nth(composite->tvbs, i);
			member_tvb = slist->data;
			break;
		}
	}
	DISSECTOR_ASSERT(member_tvb);

	if (check_offset_length_no_exception(member_tvb, abs_offset - composite->start_offsets[i],
				(gint) abs_length, &member_offset, &member_length, NULL)) {

		DISSECTOR_ASSERT(!tvb->real_data);
		return tvb_memcpy(member_tvb, target, member_offset, member_length);
	}
	else {
		/* The requested data is non-contiguous inside
		 * the member tvb. We have to memcpy() the part that's in the member tvb,
		 * then iterate across the other member tvb's, copying their portions
		 * until we have copied all data.
		 */
		retval = compute_offset_length(member_tvb, abs_offset - composite->start_offsets[i], -1,
				&member_offset, &member_length, NULL);
		DISSECTOR_ASSERT(retval);

		/* composite_memcpy() can't handle a member_length of zero.  */
		DISSECTOR_ASSERT(member_length);

		tvb_memcpy(member_tvb, target, member_offset, member_length);
		abs_offset	+= member_length;
		abs_length	-= member_length;

		/* Recurse */
		if (abs_length > 0) {
			composite_memcpy(tvb, target + member_length, abs_offset, abs_length);
		}

		return target;
	}

	DISSECTOR_ASSERT_NOT_REACHED();
}

void *
tvb_memcpy(tvbuff_t *tvb, void *target, const gint offset, size_t length)
{
	guint	abs_offset, abs_length;

	DISSECTOR_ASSERT(tvb && tvb->initialized);

	/*
	 * XXX - we should eliminate the "length = -1 means 'to the end
	 * of the tvbuff'" convention, and use other means to achieve
	 * that; this would let us eliminate a bunch of checks for
	 * negative lengths in cases where the protocol has a 32-bit
	 * length field.
	 *
	 * Allowing -1 but throwing an assertion on other negative
	 * lengths is a bit more work with the length being a size_t;
	 * instead, we check for a length <= 2^31-1.
	 */
	DISSECTOR_ASSERT(length <= 0x7FFFFFFF);
	check_offset_length(tvb, offset, (gint) length, &abs_offset, &abs_length);

	if (tvb->real_data) {
		return memcpy(target, tvb->real_data + abs_offset, abs_length);
	}

	switch(tvb->type) {
		case TVBUFF_REAL_DATA:
			DISSECTOR_ASSERT_NOT_REACHED();

		case TVBUFF_SUBSET:
			return tvb_memcpy(tvb->tvbuffs.subset.tvb, target,
					abs_offset - tvb->tvbuffs.subset.offset,
					abs_length);

		case TVBUFF_COMPOSITE:
			return composite_memcpy(tvb, target, offset, length);
	}

	DISSECTOR_ASSERT_NOT_REACHED();
	return NULL;
}


/*
 * XXX - this doesn't treat a length of -1 as an error.
 * If it did, this could replace some code that calls
 * "tvb_ensure_bytes_exist()" and then allocates a buffer and copies
 * data to it.
 *
 * "composite_ensure_contiguous_no_exception()" depends on -1 not being
 * an error; does anything else depend on this routine treating -1 as
 * meaning "to the end of the buffer"?
 */
void *
tvb_memdup(tvbuff_t *tvb, const gint offset, size_t length)
{
	guint	abs_offset, abs_length;
	void	*duped;

	DISSECTOR_ASSERT(tvb && tvb->initialized);

	check_offset_length(tvb, offset, (gint) length, &abs_offset, &abs_length);

	duped = g_malloc(abs_length);
	return tvb_memcpy(tvb, duped, abs_offset, abs_length);
}

/*
 * XXX - this doesn't treat a length of -1 as an error.
 * If it did, this could replace some code that calls
 * "tvb_ensure_bytes_exist()" and then allocates a buffer and copies
 * data to it.
 *
 * "composite_ensure_contiguous_no_exception()" depends on -1 not being
 * an error; does anything else depend on this routine treating -1 as
 * meaning "to the end of the buffer"?
 *
 * This function allocates memory from a buffer with packet lifetime.
 * You do not have to free this buffer, it will be automatically freed
 * when wireshark starts decoding the next packet.
 * Do not use this function if you want the allocated memory to be persistent
 * after the current packet has been dissected.
 */
void *
ep_tvb_memdup(tvbuff_t *tvb, const gint offset, size_t length)
{
	guint	abs_offset, abs_length;
	void	*duped;

	DISSECTOR_ASSERT(tvb && tvb->initialized);

	check_offset_length(tvb, offset, (gint) length, &abs_offset, &abs_length);

	duped = ep_alloc(abs_length);
	return tvb_memcpy(tvb, duped, abs_offset, abs_length);
}



const guint8*
tvb_get_ptr(tvbuff_t *tvb, const gint offset, const gint length)
{
	return ensure_contiguous(tvb, offset, length);
}

/* ---------------- */
guint8
tvb_get_guint8(tvbuff_t *tvb, const gint offset)
{
	const guint8 *ptr;

	ptr = fast_ensure_contiguous(tvb, offset, sizeof(guint8));
	return *ptr;
}

guint16
tvb_get_ntohs(tvbuff_t *tvb, const gint offset)
{
	const guint8 *ptr;

	ptr = fast_ensure_contiguous(tvb, offset, sizeof(guint16));
	return pntohs(ptr);
}

guint32
tvb_get_ntoh24(tvbuff_t *tvb, const gint offset)
{
	const guint8 *ptr;

	ptr = fast_ensure_contiguous(tvb, offset, 3);
	return pntoh24(ptr);
}

guint32
tvb_get_ntohl(tvbuff_t *tvb, const gint offset)
{
	const guint8 *ptr;

	ptr = fast_ensure_contiguous(tvb, offset, sizeof(guint32));
	return pntohl(ptr);
}

guint64
tvb_get_ntoh40(tvbuff_t *tvb, const gint offset)
{
	const guint8 *ptr;

	ptr = fast_ensure_contiguous(tvb, offset, 5);
	return pntoh40(ptr);
}

guint64
tvb_get_ntoh48(tvbuff_t *tvb, const gint offset)
{
	const guint8 *ptr;

	ptr = fast_ensure_contiguous(tvb, offset, 6);
	return pntoh48(ptr);
}

guint64
tvb_get_ntoh56(tvbuff_t *tvb, const gint offset)
{
	const guint8 *ptr;

	ptr = fast_ensure_contiguous(tvb, offset, 7);
	return pntoh56(ptr);
}

guint64
tvb_get_ntoh64(tvbuff_t *tvb, const gint offset)
{
	const guint8 *ptr;

	ptr = fast_ensure_contiguous(tvb, offset, sizeof(guint64));
	return pntoh64(ptr);
}

/*
 * Stuff for IEEE float handling on platforms that don't have IEEE
 * format as the native floating-point format.
 *
 * For now, we treat only the VAX as such a platform.
 *
 * XXX - other non-IEEE boxes that can run UNIX include some Crays,
 * and possibly other machines.
 *
 * It appears that the official Linux port to System/390 and
 * zArchitecture uses IEEE format floating point (not a
 * huge surprise).
 *
 * I don't know whether there are any other machines that
 * could run Wireshark and that don't use IEEE format.
 * As far as I know, all of the main commercial microprocessor
 * families on which OSes that support Wireshark can run
 * use IEEE format (x86, 68k, SPARC, MIPS, PA-RISC, Alpha,
 * IA-64, and so on).
 */

#if defined(vax)

#include <math.h>

/*
 * Single-precision.
 */
#define IEEE_SP_NUMBER_WIDTH	32	/* bits in number */
#define IEEE_SP_EXP_WIDTH	8	/* bits in exponent */
#define IEEE_SP_MANTISSA_WIDTH	23	/* IEEE_SP_NUMBER_WIDTH - 1 - IEEE_SP_EXP_WIDTH */

#define IEEE_SP_SIGN_MASK	0x80000000
#define IEEE_SP_EXPONENT_MASK	0x7F800000
#define IEEE_SP_MANTISSA_MASK	0x007FFFFF
#define IEEE_SP_INFINITY	IEEE_SP_EXPONENT_MASK

#define IEEE_SP_IMPLIED_BIT (1 << IEEE_SP_MANTISSA_WIDTH)
#define IEEE_SP_INFINITE ((1 << IEEE_SP_EXP_WIDTH) - 1)
#define IEEE_SP_BIAS ((1 << (IEEE_SP_EXP_WIDTH - 1)) - 1)

static int
ieee_float_is_zero(const guint32 w)
{
	return ((w & ~IEEE_SP_SIGN_MASK) == 0);
}

static gfloat
get_ieee_float(const guint32 w)
{
	long sign;
	long exponent;
	long mantissa;

	sign = w & IEEE_SP_SIGN_MASK;
	exponent = w & IEEE_SP_EXPONENT_MASK;
	mantissa = w & IEEE_SP_MANTISSA_MASK;

	if (ieee_float_is_zero(w)) {
		/* number is zero, unnormalized, or not-a-number */
		return 0.0;
	}
#if 0
	/*
	 * XXX - how to handle this?
	 */
	if (IEEE_SP_INFINITY == exponent) {
		/*
		 * number is positive or negative infinity, or a special value
		 */
		return (sign? MINUS_INFINITY: PLUS_INFINITY);
	}
#endif

	exponent = ((exponent >> IEEE_SP_MANTISSA_WIDTH) - IEEE_SP_BIAS) -
		IEEE_SP_MANTISSA_WIDTH;
	mantissa |= IEEE_SP_IMPLIED_BIT;

	if (sign)
		return -mantissa * pow(2, exponent);
	else
		return mantissa * pow(2, exponent);
}

/*
 * Double-precision.
 * We assume that if you don't have IEEE floating-point, you have a
 * compiler that understands 64-bit integral quantities.
 */
#define IEEE_DP_NUMBER_WIDTH	64	/* bits in number */
#define IEEE_DP_EXP_WIDTH	11	/* bits in exponent */
#define IEEE_DP_MANTISSA_WIDTH	52	/* IEEE_DP_NUMBER_WIDTH - 1 - IEEE_DP_EXP_WIDTH */

#define IEEE_DP_SIGN_MASK	0x8000000000000000LL
#define IEEE_DP_EXPONENT_MASK	0x7FF0000000000000LL
#define IEEE_DP_MANTISSA_MASK	0x000FFFFFFFFFFFFFLL
#define IEEE_DP_INFINITY	IEEE_DP_EXPONENT_MASK

#define IEEE_DP_IMPLIED_BIT (1LL << IEEE_DP_MANTISSA_WIDTH)
#define IEEE_DP_INFINITE ((1 << IEEE_DP_EXP_WIDTH) - 1)
#define IEEE_DP_BIAS ((1 << (IEEE_DP_EXP_WIDTH - 1)) - 1)

static int
ieee_double_is_zero(const guint64 w)
{
	return ((w & ~IEEE_SP_SIGN_MASK) == 0);
}

static gdouble
get_ieee_double(const guint64 w)
{
	gint64 sign;
	gint64 exponent;
	gint64 mantissa;

	sign = w & IEEE_DP_SIGN_MASK;
	exponent = w & IEEE_DP_EXPONENT_MASK;
	mantissa = w & IEEE_DP_MANTISSA_MASK;

	if (ieee_double_is_zero(w)) {
		/* number is zero, unnormalized, or not-a-number */
		return 0.0;
	}
#if 0
	/*
	 * XXX - how to handle this?
	 */
	if (IEEE_DP_INFINITY == exponent) {
		/*
		 * number is positive or negative infinity, or a special value
		 */
		return (sign? MINUS_INFINITY: PLUS_INFINITY);
	}
#endif

	exponent = ((exponent >> IEEE_DP_MANTISSA_WIDTH) - IEEE_DP_BIAS) -
		IEEE_DP_MANTISSA_WIDTH;
	mantissa |= IEEE_DP_IMPLIED_BIT;

	if (sign)
		return -mantissa * pow(2, exponent);
	else
		return mantissa * pow(2, exponent);
}
#endif

/*
 * Fetches an IEEE single-precision floating-point number, in
 * big-endian form, and returns a "float".
 *
 * XXX - should this be "double", in case there are IEEE single-
 * precision numbers that won't fit in some platform's native
 * "float" format?
 */
gfloat
tvb_get_ntohieee_float(tvbuff_t *tvb, const int offset)
{
#if defined(vax)
	return get_ieee_float(tvb_get_ntohl(tvb, offset));
#else
	union {
		gfloat f;
		guint32 w;
	} ieee_fp_union;

	ieee_fp_union.w = tvb_get_ntohl(tvb, offset);
	return ieee_fp_union.f;
#endif
}

/*
 * Fetches an IEEE double-precision floating-point number, in
 * big-endian form, and returns a "double".
 */
gdouble
tvb_get_ntohieee_double(tvbuff_t *tvb, const int offset)
{
#if defined(vax)
	union {
		guint32 w[2];
		guint64 dw;
	} ieee_fp_union;
#else
	union {
		gdouble d;
		guint32 w[2];
	} ieee_fp_union;
#endif

#ifdef WORDS_BIGENDIAN
	ieee_fp_union.w[0] = tvb_get_ntohl(tvb, offset);
	ieee_fp_union.w[1] = tvb_get_ntohl(tvb, offset+4);
#else
	ieee_fp_union.w[0] = tvb_get_ntohl(tvb, offset+4);
	ieee_fp_union.w[1] = tvb_get_ntohl(tvb, offset);
#endif
#if defined(vax)
	return get_ieee_double(ieee_fp_union.dw);
#else
	return ieee_fp_union.d;
#endif
}

guint16
tvb_get_letohs(tvbuff_t *tvb, const gint offset)
{
	const guint8 *ptr;

	ptr = fast_ensure_contiguous(tvb, offset, sizeof(guint16));
	return pletohs(ptr);
}

guint32
tvb_get_letoh24(tvbuff_t *tvb, const gint offset)
{
	const guint8 *ptr;

	ptr = fast_ensure_contiguous(tvb, offset, 3);
	return pletoh24(ptr);
}

guint32
tvb_get_letohl(tvbuff_t *tvb, const gint offset)
{
	const guint8 *ptr;

	ptr = fast_ensure_contiguous(tvb, offset, sizeof(guint32));
	return pletohl(ptr);
}

guint64
tvb_get_letoh40(tvbuff_t *tvb, const gint offset)
{
	const guint8 *ptr;

	ptr = fast_ensure_contiguous(tvb, offset, 5);
	return pletoh40(ptr);
}

guint64
tvb_get_letoh48(tvbuff_t *tvb, const gint offset)
{
	const guint8 *ptr;

	ptr = fast_ensure_contiguous(tvb, offset, 6);
	return pletoh48(ptr);
}

guint64
tvb_get_letoh56(tvbuff_t *tvb, const gint offset)
{
	const guint8 *ptr;

	ptr = fast_ensure_contiguous(tvb, offset, 7);
	return pletoh56(ptr);
}

guint64
tvb_get_letoh64(tvbuff_t *tvb, const gint offset)
{
	const guint8 *ptr;

	ptr = fast_ensure_contiguous(tvb, offset, sizeof(guint64));
	return pletoh64(ptr);
}

/*
 * Fetches an IEEE single-precision floating-point number, in
 * little-endian form, and returns a "float".
 *
 * XXX - should this be "double", in case there are IEEE single-
 * precision numbers that won't fit in some platform's native
 * "float" format?
 */
gfloat
tvb_get_letohieee_float(tvbuff_t *tvb, const int offset)
{
#if defined(vax)
	return get_ieee_float(tvb_get_letohl(tvb, offset));
#else
	union {
		gfloat f;
		guint32 w;
	} ieee_fp_union;

	ieee_fp_union.w = tvb_get_letohl(tvb, offset);
	return ieee_fp_union.f;
#endif
}

/*
 * Fetches an IEEE double-precision floating-point number, in
 * little-endian form, and returns a "double".
 */
gdouble
tvb_get_letohieee_double(tvbuff_t *tvb, const int offset)
{
#if defined(vax)
	union {
		guint32 w[2];
		guint64 dw;
	} ieee_fp_union;
#else
	union {
		gdouble d;
		guint32 w[2];
	} ieee_fp_union;
#endif

#ifdef WORDS_BIGENDIAN
	ieee_fp_union.w[0] = tvb_get_letohl(tvb, offset+4);
	ieee_fp_union.w[1] = tvb_get_letohl(tvb, offset);
#else
	ieee_fp_union.w[0] = tvb_get_letohl(tvb, offset);
	ieee_fp_union.w[1] = tvb_get_letohl(tvb, offset+4);
#endif
#if defined(vax)
	return get_ieee_double(ieee_fp_union.dw);
#else
	return ieee_fp_union.d;
#endif
}

/* Fetch an IPv4 address, in network byte order.
 * We do *not* convert them to host byte order; we leave them in
 * network byte order. */
guint32
tvb_get_ipv4(tvbuff_t *tvb, const gint offset)
{
	const guint8 *ptr;
	guint32       addr;

	ptr = fast_ensure_contiguous(tvb, offset, sizeof(guint32));
	memcpy(&addr, ptr, sizeof addr);
	return addr;
}

/* Fetch an IPv6 address. */
void
tvb_get_ipv6(tvbuff_t *tvb, const gint offset, struct e_in6_addr *addr)
{
	const guint8 *ptr;

	ptr = ensure_contiguous(tvb, offset, sizeof(*addr));
	memcpy(addr, ptr, sizeof *addr);
}

/* Fetch a GUID. */
void
tvb_get_ntohguid(tvbuff_t *tvb, const gint offset, e_guid_t *guid)
{
	ensure_contiguous(tvb, offset, sizeof(*guid));
	guid->data1 = tvb_get_ntohl(tvb, offset);
	guid->data2 = tvb_get_ntohs(tvb, offset + 4);
	guid->data3 = tvb_get_ntohs(tvb, offset + 6);
	tvb_memcpy(tvb, guid->data4, offset + 8, sizeof guid->data4);
}

void
tvb_get_letohguid(tvbuff_t *tvb, const gint offset, e_guid_t *guid)
{
	ensure_contiguous(tvb, offset, sizeof(*guid));
	guid->data1 = tvb_get_letohl(tvb, offset);
	guid->data2 = tvb_get_letohs(tvb, offset + 4);
	guid->data3 = tvb_get_letohs(tvb, offset + 6);
	tvb_memcpy(tvb, guid->data4, offset + 8, sizeof guid->data4);
}

/*
 * NOTE: to support code written when proto_tree_add_item() took a
 * gboolean as its last argument, with FALSE meaning "big-endian"
 * and TRUE meaning "little-endian", we treat any non-zero value of
 * "representation" as meaning "little-endian".
 */
void
tvb_get_guid(tvbuff_t *tvb, const gint offset, e_guid_t *guid, const guint representation)
{
	if (representation) {
		tvb_get_letohguid(tvb, offset, guid);
	} else {
		tvb_get_ntohguid(tvb, offset, guid);
	}
}

static const guint8 inverse_bit_mask8[] = {
	0xff,
	0x7f,
	0x3f,
	0x1f,
	0x0f,
	0x07,
	0x03,
	0x01
};

static const guint8 bit_mask8[] = {
	0x00,
	0x01,
	0x03,
	0x07,
	0x0f,
	0x1f,
	0x3f,
	0x7f,
	0xff
};

/* Get 1 - 8 bits */
guint8
tvb_get_bits8(tvbuff_t *tvb, guint bit_offset, const gint no_of_bits)
{
	return (guint8)_tvb_get_bits64(tvb, bit_offset, no_of_bits);
}

/* Get 1 - 16 bits */
void
tvb_get_bits_buf(tvbuff_t *tvb, guint bit_offset, gint no_of_bits, guint8 *buf, gboolean lsb0)
{
	guint8 bit_mask, bit_shift;
	/* Byte align offset */
	gint   offset = bit_offset >> 3;

	bit_offset    = bit_offset & 0x7;

	bit_mask  = (lsb0) ? 0xff : inverse_bit_mask8[bit_offset];
	bit_shift = (lsb0) ? bit_offset : (8 - bit_offset);

	if (G_LIKELY(bit_offset != 0)) {
		guint16 value = (guint16) tvb_get_guint8(tvb, offset);

		while (no_of_bits >= 8) {
			offset++;
			value = ((value & bit_mask) << 8) | tvb_get_guint8(tvb, offset);

			if (lsb0)
				*buf++ = (guint8) (GUINT16_SWAP_LE_BE(value) >> bit_shift);
			else
				*buf++ = (guint8) (value >> bit_shift);
			no_of_bits -= 8;
		}

		/* something left? */
		if (no_of_bits > 0) {
			guint8 tot_no_bits = bit_offset+no_of_bits;

			/* Overlaps with next byte? Get next byte */
			if (tot_no_bits > 8) {
				offset++;
				value = ((value & bit_mask) << 8) | tvb_get_guint8(tvb, offset);
			}

			if (lsb0) {
				if (tot_no_bits > 8)
					value = (GUINT16_SWAP_LE_BE(value) >> bit_offset) & (bit_mask8[no_of_bits]);
				else
					value = (value >> bit_offset) & (bit_mask8[no_of_bits]);

				/* value = (value & ((1 << tot_no_bits)-1)) >> bit_offset; */

			} else {
				if (tot_no_bits > 8)
					value = value >> (16 - tot_no_bits);
				else
					value = (value & bit_mask) >> (8-tot_no_bits);
			}
			*buf = (guint8) value;
		}

	} else {
		/* fast code path for bit_offset == 0 */
		while (no_of_bits >= 8) {
			*buf++ = tvb_get_guint8(tvb, offset);
			offset++;
			no_of_bits -= 8;
		}

		/* something left? */
		if (no_of_bits > 0) {
			if (lsb0)
				*buf = tvb_get_guint8(tvb, offset) & bit_mask8[no_of_bits]; /* read: ((1 << no_of_bits)-1) */
			else
				*buf = tvb_get_guint8(tvb, offset) >> (8-no_of_bits);
		}
	}
}

guint8 *
ep_tvb_get_bits(tvbuff_t *tvb, guint bit_offset, gint no_of_bits, gboolean lsb0)
{
	gint    no_of_bytes;
	guint8 *buf;

	/* XXX, no_of_bits == -1 -> to end of tvb? */

	if (no_of_bits < 0) {
		DISSECTOR_ASSERT_NOT_REACHED();
	}

	no_of_bytes = (no_of_bits >> 3) + ((no_of_bits & 0x7) != 0);	/* ceil(no_of_bits / 8.0) */
	buf         = ep_alloc(no_of_bytes);
	tvb_get_bits_buf(tvb, bit_offset, no_of_bits, buf, lsb0);
	return buf;
}

/* Get 9 - 16 bits */
guint16
tvb_get_bits16(tvbuff_t *tvb, guint bit_offset, const gint no_of_bits,const guint encoding _U_)
{
	/* note that encoding has no meaning here, as the tvb is considered to contain an octet array */
	return (guint16)_tvb_get_bits64(tvb, bit_offset, no_of_bits);
}

/* Get 1 - 32 bits */
guint32
tvb_get_bits32(tvbuff_t *tvb, guint bit_offset, const gint no_of_bits, const guint encoding _U_)
{
	/* note that encoding has no meaning here, as the tvb is considered to contain an octet array */
	return (guint32)_tvb_get_bits64(tvb, bit_offset, no_of_bits);
}

/* Get 1 - 64 bits */
guint64
tvb_get_bits64(tvbuff_t *tvb, guint bit_offset, const gint no_of_bits, const guint encoding _U_)
{
	/* note that encoding has no meaning here, as the tvb is considered to contain an octet array */
	return _tvb_get_bits64(tvb, bit_offset, no_of_bits);
}
/*
 * This function will dissect a sequence of bits that does not need to be byte aligned; the bits
 * set will be shown in the tree as ..10 10.. and the integer value returned if return_value is set.
 * Offset should be given in bits from the start of the tvb.
 * The function tolerates requests for more than 64 bits, but will only return the least significant 64 bits.
 */
static guint64
_tvb_get_bits64(tvbuff_t *tvb, guint bit_offset, const gint total_no_of_bits)
{
	guint64 value;
	guint octet_offset = bit_offset >> 3;
	guint8 required_bits_in_first_octet = 8 - (bit_offset % 8);

	if(required_bits_in_first_octet > total_no_of_bits)
	{
		/* the required bits don't extend to the end of the first octet */
		guint8 right_shift = required_bits_in_first_octet - total_no_of_bits;
		value = (tvb_get_guint8(tvb, octet_offset) >> right_shift) & bit_mask8[total_no_of_bits % 8];
	}
	else
	{
		guint8 remaining_bit_length = total_no_of_bits;

		/* get the bits up to the first octet boundary */
		value = 0;
		required_bits_in_first_octet %= 8;
		if(required_bits_in_first_octet != 0)
		{
			value = tvb_get_guint8(tvb, octet_offset) & bit_mask8[required_bits_in_first_octet];
			remaining_bit_length -= required_bits_in_first_octet;
			octet_offset ++;
		}
		/* take the biggest words, shorts or octets that we can */
		while (remaining_bit_length > 7)
		{
			switch (remaining_bit_length >> 4)
			{
			case 0:
				/* 8 - 15 bits. (note that 0 - 7 would have dropped out of the while() loop) */
				value <<= 8;
				value += tvb_get_guint8(tvb, octet_offset);
				remaining_bit_length -= 8;
				octet_offset ++;
				break;

			case 1:
				/* 16 - 31 bits */
				value <<= 16;
				value += tvb_get_ntohs(tvb, octet_offset);
				remaining_bit_length -= 16;
				octet_offset += 2;
				break;

			case 2:
			case 3:
				/* 32 - 63 bits */
				value <<= 32;
				value += tvb_get_ntohl(tvb, octet_offset);
				remaining_bit_length -= 32;
				octet_offset += 4;
				break;

			default:
				/* 64 bits (or more???) */
				value = tvb_get_ntoh64(tvb, octet_offset);
				remaining_bit_length -= 64;
				octet_offset += 8;
				break;
			}
		}
		/* get bits from any partial octet at the tail */
		if(remaining_bit_length)
		{
			value <<= remaining_bit_length;
			value += (tvb_get_guint8(tvb, octet_offset) >> (8 - remaining_bit_length));
		}
	}
	return value;
}
/* Get 1 - 32 bits (should be deprecated as same as tvb_get_bits32??) */
guint32
tvb_get_bits(tvbuff_t *tvb, const guint bit_offset, const gint no_of_bits, const guint encoding _U_)
{
	/* note that encoding has no meaning here, as the tvb is considered to contain an octet array */
	return (guint32)_tvb_get_bits64(tvb, bit_offset, no_of_bits);
}

/* Find first occurence of needle in tvbuff, starting at offset. Searches
 * at most maxlength number of bytes; if maxlength is -1, searches to
 * end of tvbuff.
 * Returns the offset of the found needle, or -1 if not found.
 * Will not throw an exception, even if maxlength exceeds boundary of tvbuff;
 * in that case, -1 will be returned if the boundary is reached before
 * finding needle. */
gint
tvb_find_guint8(tvbuff_t *tvb, const gint offset, const gint maxlength, const guint8 needle)
{
	const guint8 *result;
	guint	      abs_offset, junk_length;
	guint	      tvbufflen;
	guint	      limit;

	DISSECTOR_ASSERT(tvb && tvb->initialized);

	check_offset_length(tvb, offset, 0, &abs_offset, &junk_length);

	/* Only search to end of tvbuff, w/o throwing exception. */
	tvbufflen = tvb_length_remaining(tvb, abs_offset);
	if (maxlength == -1) {
		/* No maximum length specified; search to end of tvbuff. */
		limit = tvbufflen;
	}
	else if (tvbufflen < (guint) maxlength) {
		/* Maximum length goes past end of tvbuff; search to end
		   of tvbuff. */
		limit = tvbufflen;
	}
	else {
		/* Maximum length doesn't go past end of tvbuff; search
		   to that value. */
		limit = maxlength;
	}

	/* If we have real data, perform our search now. */
	if (tvb->real_data) {
		result = memchr(tvb->real_data + abs_offset, needle, limit);
		if (result == NULL) {
			return -1;
		}
		else {
			return (gint) (result - tvb->real_data);
		}
	}

	switch(tvb->type) {
		case TVBUFF_REAL_DATA:
			DISSECTOR_ASSERT_NOT_REACHED();

		case TVBUFF_SUBSET:
			return tvb_find_guint8(tvb->tvbuffs.subset.tvb,
					abs_offset - tvb->tvbuffs.subset.offset,
					limit, needle);

		case TVBUFF_COMPOSITE:
			DISSECTOR_ASSERT_NOT_REACHED();
			/* XXX - return composite_find_guint8(tvb, offset, limit, needle); */
	}

	DISSECTOR_ASSERT_NOT_REACHED();
	return -1;
}

/* Find first occurence of any of the needles in tvbuff, starting at offset.
 * Searches at most maxlength number of bytes; if maxlength is -1, searches
 * to end of tvbuff.
 * Returns the offset of the found needle, or -1 if not found.
 * Will not throw an exception, even if maxlength exceeds boundary of tvbuff;
 * in that case, -1 will be returned if the boundary is reached before
 * finding needle. */
gint
tvb_pbrk_guint8(tvbuff_t *tvb, const gint offset, const gint maxlength, const guint8 *needles, guchar *found_needle)
{
	const guint8 *result;
	guint	      abs_offset, junk_length;
	guint	      tvbufflen;
	guint	      limit;

	DISSECTOR_ASSERT(tvb && tvb->initialized);

	check_offset_length(tvb, offset, 0, &abs_offset, &junk_length);

	/* Only search to end of tvbuff, w/o throwing exception. */
	tvbufflen = tvb_length_remaining(tvb, abs_offset);
	if (maxlength == -1) {
		/* No maximum length specified; search to end of tvbuff. */
		limit = tvbufflen;
	}
	else if (tvbufflen < (guint) maxlength) {
		/* Maximum length goes past end of tvbuff; search to end
		   of tvbuff. */
		limit = tvbufflen;
	}
	else {
		/* Maximum length doesn't go past end of tvbuff; search
		   to that value. */
		limit = maxlength;
	}

	/* If we have real data, perform our search now. */
	if (tvb->real_data) {
		result = guint8_pbrk(tvb->real_data + abs_offset, limit, needles, found_needle);
		if (result == NULL) {
			return -1;
		}
		else {
			return (gint) (result - tvb->real_data);
		}
	}

	switch(tvb->type) {
		case TVBUFF_REAL_DATA:
			DISSECTOR_ASSERT_NOT_REACHED();

		case TVBUFF_SUBSET:
			return tvb_pbrk_guint8(tvb->tvbuffs.subset.tvb,
					abs_offset - tvb->tvbuffs.subset.offset,
					limit, needles, found_needle);

		case TVBUFF_COMPOSITE:
			DISSECTOR_ASSERT_NOT_REACHED();
			/* XXX - return composite_pbrk_guint8(tvb, offset, limit, needle); */
	}

	DISSECTOR_ASSERT_NOT_REACHED();
	return -1;
}

/* Find size of stringz (NUL-terminated string) by looking for terminating
 * NUL.  The size of the string includes the terminating NUL.
 *
 * If the NUL isn't found, it throws the appropriate exception.
 */
guint
tvb_strsize(tvbuff_t *tvb, const gint offset)
{
	guint abs_offset, junk_length;
	gint  nul_offset;

	DISSECTOR_ASSERT(tvb && tvb->initialized);

	check_offset_length(tvb, offset, 0, &abs_offset, &junk_length);
	nul_offset = tvb_find_guint8(tvb, abs_offset, -1, 0);
	if (nul_offset == -1) {
		/*
		 * OK, we hit the end of the tvbuff, so we should throw
		 * an exception.
		 *
		 * Did we hit the end of the captured data, or the end
		 * of the actual data?	If there's less captured data
		 * than actual data, we presumably hit the end of the
		 * captured data, otherwise we hit the end of the actual
		 * data.
		 */
		if (tvb_length(tvb) < tvb_reported_length(tvb)) {
			THROW(BoundsError);
		} else {
			THROW(ReportedBoundsError);
		}
	}
	return (nul_offset - abs_offset) + 1;
}

/* UTF-16/UCS-2 version of tvb_strsize */
/* Returns number of bytes including the (two-bytes) null terminator */
guint
tvb_unicode_strsize(tvbuff_t *tvb, const gint offset)
{
	guint     i = 0;
	gunichar2 uchar;

	DISSECTOR_ASSERT(tvb && tvb->initialized);

	do {
		/* Endianness doesn't matter when looking for null */
		uchar = tvb_get_ntohs(tvb, offset + i);
		i += 2;
	} while(uchar != 0);

	return i;
}

/* Find length of string by looking for end of string ('\0'), up to
 * 'maxlength' characters'; if 'maxlength' is -1, searches to end
 * of tvbuff.
 * Returns -1 if 'maxlength' reached before finding EOS. */
gint
tvb_strnlen(tvbuff_t *tvb, const gint offset, const guint maxlength)
{
	gint  result_offset;
	guint abs_offset, junk_length;

	DISSECTOR_ASSERT(tvb && tvb->initialized);

	check_offset_length(tvb, offset, 0, &abs_offset, &junk_length);

	result_offset = tvb_find_guint8(tvb, abs_offset, maxlength, 0);

	if (result_offset == -1) {
		return -1;
	}
	else {
		return result_offset - abs_offset;
	}
}

/*
 * Implement strneql etc
 */

/*
 * Call strncmp after checking if enough chars left, returning 0 if
 * it returns 0 (meaning "equal") and -1 otherwise, otherwise return -1.
 */
gint
tvb_strneql(tvbuff_t *tvb, const gint offset, const gchar *str, const size_t size)
{
	const guint8 *ptr;

	ptr = ensure_contiguous_no_exception(tvb, offset, (gint)size, NULL);

	if (ptr) {
		int cmp = strncmp((const char *)ptr, str, size);

		/*
		 * Return 0 if equal, -1 otherwise.
		 */
		return (cmp == 0 ? 0 : -1);
	} else {
		/*
		 * Not enough characters in the tvbuff to match the
		 * string.
		 */
		return -1;
	}
}

/*
 * Call g_ascii_strncasecmp after checking if enough chars left, returning
 * 0 if it returns 0 (meaning "equal") and -1 otherwise, otherwise return -1.
 */
gint
tvb_strncaseeql(tvbuff_t *tvb, const gint offset, const gchar *str, const size_t size)
{
	const guint8 *ptr;

	ptr = ensure_contiguous_no_exception(tvb, offset, (gint)size, NULL);

	if (ptr) {
		int cmp = g_ascii_strncasecmp((const char *)ptr, str, size);

		/*
		 * Return 0 if equal, -1 otherwise.
		 */
		return (cmp == 0 ? 0 : -1);
	} else {
		/*
		 * Not enough characters in the tvbuff to match the
		 * string.
		 */
		return -1;
	}
}

/*
 * Call memcmp after checking if enough chars left, returning 0 if
 * it returns 0 (meaning "equal") and -1 otherwise, otherwise return -1.
 */
gint
tvb_memeql(tvbuff_t *tvb, const gint offset, const guint8 *str, size_t size)
{
	const guint8 *ptr;

	ptr = ensure_contiguous_no_exception(tvb, offset, (gint) size, NULL);

	if (ptr) {
		int cmp = memcmp(ptr, str, size);

		/*
		 * Return 0 if equal, -1 otherwise.
		 */
		return (cmp == 0 ? 0 : -1);
	} else {
		/*
		 * Not enough characters in the tvbuff to match the
		 * string.
		 */
		return -1;
	}
}

/* Convert a string from Unicode to ASCII.	At the moment we fake it by
 * replacing all non-ASCII characters with a '.' )-:  The caller must
 * free the result returned.  The len parameter is the number of guint16's
 * to convert from Unicode. */
/* XXX - this function has been superceded by tvb_get_unicode_string() */
char *
tvb_fake_unicode(tvbuff_t *tvb, int offset, const int len, const gboolean little_endian)
{
	char    *buffer;
	int      i;
	guint16  character;

	/* Make sure we have enough data before allocating the buffer,
	   so we don't blow up if the length is huge. */
	tvb_ensure_bytes_exist(tvb, offset, 2*len);

	/* We know we won't throw an exception, so we don't have to worry
	   about leaking this buffer. */
	buffer = g_malloc(len + 1);

	for (i = 0; i < len; i++) {
		character = little_endian ? tvb_get_letohs(tvb, offset)
					  : tvb_get_ntohs(tvb, offset);
		buffer[i] = character < 256 ? character : '.';
		offset += 2;
	}

	buffer[len] = 0;

	return buffer;
}

/* Convert a string from Unicode to ASCII.	At the moment we fake it by
 * replacing all non-ASCII characters with a '.' )-:   The len parameter is
 * the number of guint16's to convert from Unicode.
 *
 * This function allocates memory from a buffer with packet lifetime.
 * You do not have to free this buffer, it will be automatically freed
 * when wireshark starts decoding the next packet.
 */
/* XXX: This has been replaced by tvb_get_ephemeral_unicode_string() */
char *
tvb_get_ephemeral_faked_unicode(tvbuff_t *tvb, int offset, const int len, const gboolean little_endian)
{
	char    *buffer;
	int      i;
	guint16  character;

	/* Make sure we have enough data before allocating the buffer,
	   so we don't blow up if the length is huge. */
	tvb_ensure_bytes_exist(tvb, offset, 2*len);

	/* We know we won't throw an exception, so we don't have to worry
	   about leaking this buffer. */
	buffer = ep_alloc(len + 1);

	for (i = 0; i < len; i++) {
		character = little_endian ? tvb_get_letohs(tvb, offset)
					  : tvb_get_ntohs(tvb, offset);
		buffer[i] = character < 256 ? character : '.';
		offset += 2;
	}

	buffer[len] = 0;

	return buffer;
}

/*
 * Format the data in the tvb from offset for length ...
 */

gchar *
tvb_format_text(tvbuff_t *tvb, const gint offset, const gint size)
{
	const guint8 *ptr;
	gint          len = size;

	if ((ptr = ensure_contiguous(tvb, offset, size)) == NULL) {
		len = tvb_length_remaining(tvb, offset);
		ptr = ensure_contiguous(tvb, offset, len);
	}

	return format_text(ptr, len);
}

/*
 * Format the data in the tvb from offset for length ...
 */

gchar *
tvb_format_text_wsp(tvbuff_t *tvb, const gint offset, const gint size)
{
	const guint8 *ptr;
	gint          len = size;

	if ((ptr = ensure_contiguous(tvb, offset, size)) == NULL) {

		len = tvb_length_remaining(tvb, offset);
		ptr = ensure_contiguous(tvb, offset, len);

	}

	return format_text_wsp(ptr, len);

}

/*
 * Like "tvb_format_text()", but for null-padded strings; don't show
 * the null padding characters as "\000".
 */
gchar *
tvb_format_stringzpad(tvbuff_t *tvb, const gint offset, const gint size)
{
	const guint8 *ptr, *p;
	gint          len = size;
	gint          stringlen;

	if ((ptr = ensure_contiguous(tvb, offset, size)) == NULL) {

		len = tvb_length_remaining(tvb, offset);
		ptr = ensure_contiguous(tvb, offset, len);

	}

	for (p = ptr, stringlen = 0; stringlen < len && *p != '\0'; p++, stringlen++)
		;
	return format_text(ptr, stringlen);

}

/*
 * Like "tvb_format_text_wsp()", but for null-padded strings; don't show
 * the null padding characters as "\000".
 */
gchar *
tvb_format_stringzpad_wsp(tvbuff_t *tvb, const gint offset, const gint size)
{
	const guint8 *ptr, *p;
	gint          len = size;
	gint          stringlen;

	if ((ptr = ensure_contiguous(tvb, offset, size)) == NULL) {

		len = tvb_length_remaining(tvb, offset);
		ptr = ensure_contiguous(tvb, offset, len);

	}

	for (p = ptr, stringlen = 0; stringlen < len && *p != '\0'; p++, stringlen++)
		;
	return format_text_wsp(ptr, stringlen);

}

/*
 * Given a tvbuff, an offset, and a length, allocate a buffer big enough
 * to hold a non-null-terminated string of that length at that offset,
 * plus a trailing '\0', copy the string into it, and return a pointer
 * to the string.
 *
 * Throws an exception if the tvbuff ends before the string does.
 */
guint8 *
tvb_get_string(tvbuff_t *tvb, const gint offset, const gint length)
{
	const guint8 *ptr;
	guint8       *strbuf = NULL;

	tvb_ensure_bytes_exist(tvb, offset, length);

	ptr    = ensure_contiguous(tvb, offset, length);
	strbuf = g_malloc(length + 1);
	if (length != 0) {
		memcpy(strbuf, ptr, length);
	}
	strbuf[length] = '\0';
	return strbuf;
}

/*
 * Unicode (UTF-16) version of tvb_get_string()
 * XXX - this is UCS-2, not UTF-16, as it doesn't handle surrogate pairs
 *
 * Encoding paramter should be ENC_BIG_ENDIAN or ENC_LITTLE_ENDIAN
 *
 * Specify length in bytes
 *
 * Returns an UTF-8 string that must be freed by the caller
 */
gchar *
tvb_get_unicode_string(tvbuff_t *tvb, const gint offset, gint length, const guint encoding)
{
	gunichar2  uchar;
	gint       i;           /* Byte counter for tvbuff */
	GString   *strbuf = NULL;

	tvb_ensure_bytes_exist(tvb, offset, length);

	strbuf = g_string_new(NULL);

	for(i = 0; i < length; i += 2) {

		if (encoding == ENC_BIG_ENDIAN)
			uchar = tvb_get_ntohs(tvb, offset + i);
		else
			uchar = tvb_get_letohs(tvb, offset + i);

		g_string_append_unichar(strbuf, uchar);
	}

	return g_string_free(strbuf, FALSE);
}

/*
 * Given a tvbuff, an offset, a length, and an encoding, allocate a
 * buffer big enough to hold a non-null-terminated string of that length
 * at that offset, plus a trailing '\0', copy into the buffer the
 * string as converted from the appropriate encoding to UTF-8, and
 * return a pointer to the string.
 *
 * Throws an exception if the tvbuff ends before the string does.
 *
 * This function allocates memory from a buffer with packet lifetime.
 * You do not have to free this buffer, it will be automatically freed
 * when wireshark starts decoding the next packet.
 * Do not use this function if you want the allocated memory to be persistent
 * after the current packet has been dissected.
 */
guint8 *
tvb_get_ephemeral_string_enc(tvbuff_t *tvb, const gint offset,
			     const gint length, const guint encoding)
{
	const guint8 *ptr;
	guint8       *strbuf;

	switch (encoding & ENC_CHARENCODING_MASK) {

	case ENC_ASCII:
	default:
		/*
		 * For now, we treat bogus values as meaning
		 * "ASCII" rather than reporting an error,
		 * for the benefit of old dissectors written
		 * when the last argument to proto_tree_add_item()
		 * was a gboolean for the byte order, not an
		 * encoding value, and passed non-zero values
		 * other than TRUE to mean "little-endian".
		 *
		 * XXX - should map all octets with the 8th bit
		 * not set to a "substitute" UTF-8 character.
		 */
		strbuf = tvb_get_ephemeral_string(tvb, offset, length);
		break;

	case ENC_UTF_8:
		/*
		 * XXX - should map all invalid UTF-8 sequences
		 * to a "substitute" UTF-8 character.
		 */
		strbuf = tvb_get_ephemeral_string(tvb, offset, length);
		break;

	case ENC_UTF_16:
		/*
		 * XXX - needs to handle surrogate pairs and to map
		 * invalid characters and sequences to a "substitute"
		 * UTF-8 character.
		 */
		strbuf = tvb_get_ephemeral_unicode_string(tvb, offset, length,
		    encoding & ENC_LITTLE_ENDIAN);
		break;

	case ENC_UCS_2:
		/*
		 * XXX - needs to map values that are not valid UCS-2
		 * characters (such as, I think, values used as the
		 * components of a UTF-16 surrogate pair) to a
		 * "substitute" UTF-8 character.
		 */
		strbuf = tvb_get_ephemeral_unicode_string(tvb, offset, length,
		    encoding & ENC_LITTLE_ENDIAN);
		break;

	case ENC_EBCDIC:
		/*
		 * XXX - do the copy and conversion in one pass.
		 *
		 * XXX - multiple "dialects" of EBCDIC?
		 */
		tvb_ensure_bytes_exist(tvb, offset, length); /* make sure length = -1 fails */
		strbuf = ep_alloc(length + 1);
		if (length != 0) {
			ptr = ensure_contiguous(tvb, offset, length);
			memcpy(strbuf, ptr, length);
			EBCDIC_to_ASCII(strbuf, length);
		}
		strbuf[length] = '\0';
		break;
	}
	return strbuf;
}

guint8 *
tvb_get_ephemeral_string(tvbuff_t *tvb, const gint offset, const gint length)
{
	guint8       *strbuf;

	tvb_ensure_bytes_exist(tvb, offset, length); /* make sure length = -1 fails */
	strbuf = ep_alloc(length + 1);
	tvb_memcpy(tvb, strbuf, offset, length);
	strbuf[length] = '\0';
	return strbuf;
}

/*
 * Unicode (UTF-16) version of tvb_get_ephemeral_string()
 * XXX - this is UCS-2, not UTF-16, as it doesn't handle surrogate pairs
 *
 * Encoding parameter should be ENC_BIG_ENDIAN or ENC_LITTLE_ENDIAN
 *
 * Specify length in bytes
 *
 * Returns an ep_ allocated UTF-8 string
 */
gchar *
tvb_get_ephemeral_unicode_string(tvbuff_t *tvb, const gint offset, gint length, const guint encoding)
{
	/* Longest UTF-8 character takes 6 bytes + 1 byte for NUL, round it to 8B */
	gchar          tmpbuf[8];
	gunichar2      uchar;
	gint           i;       /* Byte counter for tvbuff */
	gint           tmpbuf_len;
	emem_strbuf_t *strbuf = NULL;

	tvb_ensure_bytes_exist(tvb, offset, length);

	strbuf = ep_strbuf_new(NULL);

	for(i = 0; i < length; i += 2) {

		if (encoding == ENC_BIG_ENDIAN)
			uchar = tvb_get_ntohs(tvb, offset + i);
		else
			uchar = tvb_get_letohs(tvb, offset + i);

		tmpbuf_len = g_unichar_to_utf8(uchar, tmpbuf);

		/* NULL terminate the tmpbuf so ep_strbuf_append knows where
		 * to stop */
		tmpbuf[tmpbuf_len] = '\0';

		ep_strbuf_append(strbuf, tmpbuf);
	}

	return strbuf->str;
}

/*
 * Given a tvbuff, an offset, and a length, allocate a buffer big enough
 * to hold a non-null-terminated string of that length at that offset,
 * plus a trailing '\0', copy the string into it, and return a pointer
 * to the string.
 *
 * Throws an exception if the tvbuff ends before the string does.
 *
 * This function allocates memory from a buffer with capture session lifetime.
 * You do not have to free this buffer, it will be automatically freed
 * when wireshark starts or opens a new capture.
 */
guint8 *
tvb_get_seasonal_string(tvbuff_t *tvb, const gint offset, const gint length)
{
	const guint8 *ptr;
	guint8       *strbuf = NULL;

	tvb_ensure_bytes_exist(tvb, offset, length);

	ptr    = ensure_contiguous(tvb, offset, length);
	strbuf = se_alloc(length + 1);
	if (length != 0) {
		memcpy(strbuf, ptr, length);
	}
	strbuf[length] = '\0';
	return strbuf;
}

/*
 * Given a tvbuff, an offset, and an encoding, with the offset assumed
 * to refer to a null-terminated string, find the length of that string
 * (and throw an exception if the tvbuff ends before we find the null),
 * allocate a buffer big enough to hold the string, copy the string into
 * it, and return a pointer to the string; if the encoding is EBCDIC, map
 * the string from EBCDIC to ASCII.  Also return the length of the
 * string (including the terminating null) through a pointer.
 */
guint8 *
tvb_get_stringz_enc(tvbuff_t *tvb, const gint offset, gint *lengthp, const guint encoding)
{
	guint   size;
	guint8 *strptr;

	size   = tvb_strsize(tvb, offset);
	strptr = g_malloc(size);
	tvb_memcpy(tvb, strptr, offset, size);
	if ((encoding & ENC_CHARENCODING_MASK) == ENC_EBCDIC)
		EBCDIC_to_ASCII(strptr, size);
	if (lengthp)
		*lengthp = size;
	return strptr;
}

guint8 *
tvb_get_stringz(tvbuff_t *tvb, const gint offset, gint *lengthp)
{
	return tvb_get_stringz_enc(tvb, offset, lengthp, ENC_UTF_8|ENC_NA);
}

/*
 * Given a tvbuff and an offset, with the offset assumed to refer to
 * a null-terminated string, find the length of that string (and throw
 * an exception if the tvbuff ends before we find the null), ensure that
 * the TVB is flat, and return a pointer to the string (in the TVB).
 * Also return the length of the string (including the terminating null)
 * through a pointer.
 *
 * As long as we aren't using composite TVBs, this saves the cycles used
 * (often unnecessariliy) in allocating a buffer and copying the string into
 * it.  (If we do start using composite TVBs, we may want to replace this
 * function with the _ephemeral versoin.)
 */
const guint8 *
tvb_get_const_stringz(tvbuff_t *tvb, const gint offset, gint *lengthp)
{
	guint         size;
	const guint8 *strptr;

	size   = tvb_strsize(tvb, offset);
	strptr = ensure_contiguous(tvb, offset, size);
	if (lengthp)
		*lengthp = size;
	return strptr;
}

/*
 * Given a tvbuff and an offset, with the offset assumed to refer to
 * a null-terminated string, find the length of that string (and throw
 * an exception if the tvbuff ends before we find the null), allocate
 * a buffer big enough to hold the string, copy the string into it,
 * and return a pointer to the string.	Also return the length of the
 * string (including the terminating null) through a pointer.
 *
 * This function allocates memory from a buffer with packet lifetime.
 * You do not have to free this buffer, it will be automatically freed
 * when wireshark starts decoding the next packet.
 * Do not use this function if you want the allocated memory to be persistent
 * after the current packet has been dissected.
 */
guint8 *
tvb_get_ephemeral_stringz_enc(tvbuff_t *tvb, const gint offset, gint *lengthp, const guint encoding)
{
	guint   size;
	guint8 *strptr;

	switch (encoding & ENC_CHARENCODING_MASK) {

	case ENC_ASCII:
	default:
		/*
		 * For now, we treat bogus values as meaning
		 * "ASCII" rather than reporting an error,
		 * for the benefit of old dissectors written
		 * when the last argument to proto_tree_add_item()
		 * was a gboolean for the byte order, not an
		 * encoding value, and passed non-zero values
		 * other than TRUE to mean "little-endian".
		 *
		 * XXX - should map all octets with the 8th bit
		 * not set to a "substitute" UTF-8 character.
		 */
		strptr = tvb_get_ephemeral_stringz(tvb, offset, lengthp);
		break;

	case ENC_UTF_8:
		/*
		 * XXX - should map all invalid UTF-8 sequences
		 * to a "substitute" UTF-8 character.
		 */
		strptr = tvb_get_ephemeral_stringz(tvb, offset, lengthp);
		break;

	case ENC_UTF_16:
		/*
		 * XXX - needs to handle surrogate pairs and to map
		 * invalid characters and sequences to a "substitute"
		 * UTF-8 character.
		 */
		strptr = tvb_get_ephemeral_unicode_stringz(tvb, offset, lengthp,
		    encoding & ENC_LITTLE_ENDIAN);
		break;

	case ENC_UCS_2:
		/*
		 * XXX - needs to map values that are not valid UCS-2
		 * characters (such as, I think, values used as the
		 * components of a UTF-16 surrogate pair) to a
		 * "substitute" UTF-8 character.
		 */
		strptr = tvb_get_ephemeral_unicode_stringz(tvb, offset, lengthp,
		    encoding & ENC_LITTLE_ENDIAN);
		break;

	case ENC_EBCDIC:
		/*
		 * XXX - do the copy and conversion in one pass.
		 *
		 * XXX - multiple "dialects" of EBCDIC?
		 */
		size = tvb_strsize(tvb, offset);
		strptr = ep_alloc(size);
		tvb_memcpy(tvb, strptr, offset, size);
		EBCDIC_to_ASCII(strptr, size);
		if (lengthp)
			*lengthp = size;
		break;
	}

	return strptr;
}

guint8 *
tvb_get_ephemeral_stringz(tvbuff_t *tvb, const gint offset, gint *lengthp)
{
	guint   size;
	guint8 *strptr;

	size   = tvb_strsize(tvb, offset);
	strptr = ep_alloc(size);
	tvb_memcpy(tvb, strptr, offset, size);
	if (lengthp)
		*lengthp = size;
	return strptr;
}

/*
 * Unicode (UTF-16) version of tvb_get_ephemeral_stringz()
 *
 * Encoding paramter should be ENC_BIG_ENDIAN or ENC_LITTLE_ENDIAN
 *
 * Returns an ep_ allocated UTF-8 string and updates lengthp pointer with length of string (in bytes)
 */
gchar *
tvb_get_ephemeral_unicode_stringz(tvbuff_t *tvb, const gint offset, gint *lengthp, const guint encoding)
{
	/* Longest UTF-8 character takes 6 bytes + 1 byte for NUL, round it to 8B */
	gchar          tmpbuf[8];
	gunichar2      uchar;
	gint           size;    /* Number of UTF-16 characters */
	gint           i;       /* Byte counter for tvbuff */
	gint           tmpbuf_len;
	emem_strbuf_t *strbuf = NULL;

	strbuf = ep_strbuf_new(NULL);

	size = tvb_unicode_strsize(tvb, offset);

	for(i = 0; i < size; i += 2) {

		if (encoding == ENC_BIG_ENDIAN)
			uchar = tvb_get_ntohs(tvb, offset + i);
		else
			uchar = tvb_get_letohs(tvb, offset + i);

		tmpbuf_len = g_unichar_to_utf8(uchar, tmpbuf);

		/* NULL terminate the tmpbuf so ep_strbuf_append knows where
		 * to stop */
		tmpbuf[tmpbuf_len] = '\0';

		ep_strbuf_append(strbuf, tmpbuf);
	}

	if (lengthp)
		*lengthp = i; /* Number of *bytes* processed */

	return strbuf->str;
}

/*
 * Given a tvbuff and an offset, with the offset assumed to refer to
 * a null-terminated string, find the length of that string (and throw
 * an exception if the tvbuff ends before we find the null), allocate
 * a buffer big enough to hold the string, copy the string into it,
 * and return a pointer to the string.	Also return the length of the
 * string (including the terminating null) through a pointer.
 *
 * This function allocates memory from a buffer with capture session lifetime.
 * You do not have to free this buffer, it will be automatically freed
 * when wireshark starts or opens a new capture.
 */
guint8 *
tvb_get_seasonal_stringz(tvbuff_t *tvb, const gint offset, gint *lengthp)
{
	guint   size;
	guint8 *strptr;

	size   = tvb_strsize(tvb, offset);
	strptr = se_alloc(size);
	tvb_memcpy(tvb, strptr, offset, size);
	if (lengthp)
		*lengthp = size;
	return strptr;
}

/* Looks for a stringz (NUL-terminated string) in tvbuff and copies
 * no more than bufsize number of bytes, including terminating NUL, to buffer.
 * Returns length of string (not including terminating NUL), or -1 if the string was
 * truncated in the buffer due to not having reached the terminating NUL.
 * In this way, it acts like g_snprintf().
 *
 * bufsize MUST be greater than 0.
 *
 * When processing a packet where the remaining number of bytes is less
 * than bufsize, an exception is not thrown if the end of the packet
 * is reached before the NUL is found. If no NUL is found before reaching
 * the end of the short packet, -1 is still returned, and the string
 * is truncated with a NUL, albeit not at buffer[bufsize - 1], but
 * at the correct spot, terminating the string.
 *
 * *bytes_copied will contain the number of bytes actually copied,
 * including the terminating-NUL.
 */
static gint
_tvb_get_nstringz(tvbuff_t *tvb, const gint offset, const guint bufsize, guint8* buffer, gint *bytes_copied)
{
	gint     stringlen;
	guint    abs_offset, junk_length;
	gint     limit, len;
	gboolean decreased_max = FALSE;

	check_offset_length(tvb, offset, 0, &abs_offset, &junk_length);

	/* There must at least be room for the terminating NUL. */
	DISSECTOR_ASSERT(bufsize != 0);

	/* If there's no room for anything else, just return the NUL. */
	if (bufsize == 1) {
		buffer[0] = 0;
		*bytes_copied = 1;
		return 0;
	}

	/* Only read to end of tvbuff, w/o throwing exception. */
	len = tvb_length_remaining(tvb, abs_offset);

	/* check_offset_length() won't throw an exception if we're
	 * looking at the byte immediately after the end of the tvbuff. */
	if (len == 0) {
		THROW(ReportedBoundsError);
	}

	/* This should not happen because check_offset_length() would
	 * have already thrown an exception if 'offset' were out-of-bounds.
	 */
	DISSECTOR_ASSERT(len != -1);

	/*
	 * If we've been passed a negative number, bufsize will
	 * be huge.
	 */
	DISSECTOR_ASSERT(bufsize <= G_MAXINT);

	if ((guint)len < bufsize) {
		limit = len;
		decreased_max = TRUE;
	}
	else {
		limit = bufsize;
	}

	stringlen = tvb_strnlen(tvb, abs_offset, limit - 1);
	/* If NUL wasn't found, copy the data and return -1 */
	if (stringlen == -1) {
		tvb_memcpy(tvb, buffer, abs_offset, limit);
		if (decreased_max) {
			buffer[limit] = 0;
			/* Add 1 for the extra NUL that we set at buffer[limit],
			 * pretending that it was copied as part of the string. */
			*bytes_copied = limit + 1;
		}
		else {
			*bytes_copied = limit;
		}
		return -1;
	}

	/* Copy the string to buffer */
	tvb_memcpy(tvb, buffer, abs_offset, stringlen + 1);
	*bytes_copied = stringlen + 1;
	return stringlen;
}

/* Looks for a stringz (NUL-terminated string) in tvbuff and copies
 * no more than bufsize number of bytes, including terminating NUL, to buffer.
 * Returns length of string (not including terminating NUL), or -1 if the string was
 * truncated in the buffer due to not having reached the terminating NUL.
 * In this way, it acts like g_snprintf().
 *
 * When processing a packet where the remaining number of bytes is less
 * than bufsize, an exception is not thrown if the end of the packet
 * is reached before the NUL is found. If no NUL is found before reaching
 * the end of the short packet, -1 is still returned, and the string
 * is truncated with a NUL, albeit not at buffer[bufsize - 1], but
 * at the correct spot, terminating the string.
 */
gint
tvb_get_nstringz(tvbuff_t *tvb, const gint offset, const guint bufsize, guint8* buffer)
{
	gint bytes_copied;

	DISSECTOR_ASSERT(tvb && tvb->initialized);

	return _tvb_get_nstringz(tvb, offset, bufsize, buffer, &bytes_copied);
}

/* Like tvb_get_nstringz(), but never returns -1. The string is guaranteed to
 * have a terminating NUL. If the string was truncated when copied into buffer,
 * a NUL is placed at the end of buffer to terminate it.
 */
gint
tvb_get_nstringz0(tvbuff_t *tvb, const gint offset, const guint bufsize, guint8* buffer)
{
	gint	len, bytes_copied;

	DISSECTOR_ASSERT(tvb && tvb->initialized);

	len = _tvb_get_nstringz(tvb, offset, bufsize, buffer, &bytes_copied);

	if (len == -1) {
		buffer[bufsize - 1] = 0;
		return bytes_copied - 1;
	}
	else {
		return len;
	}
}

/*
 * Given a tvbuff, an offset into the tvbuff, and a length that starts
 * at that offset (which may be -1 for "all the way to the end of the
 * tvbuff"), find the end of the (putative) line that starts at the
 * specified offset in the tvbuff, going no further than the specified
 * length.
 *
 * Return the length of the line (not counting the line terminator at
 * the end), or, if we don't find a line terminator:
 *
 *	if "deseg" is true, return -1;
 *
 *	if "deseg" is false, return the amount of data remaining in
 *	the buffer.
 *
 * Set "*next_offset" to the offset of the character past the line
 * terminator, or past the end of the buffer if we don't find a line
 * terminator.	(It's not set if we return -1.)
 */
gint
tvb_find_line_end(tvbuff_t *tvb, const gint offset, int len, gint *next_offset, const gboolean desegment)
{
	gint   eob_offset;
	gint   eol_offset;
	int    linelen;
	guchar found_needle = 0;

	if (len == -1)
		len = tvb_length_remaining(tvb, offset);
	/*
	 * XXX - what if "len" is still -1, meaning "offset is past the
	 * end of the tvbuff"?
	 */
	eob_offset = offset + len;

	/*
	 * Look either for a CR or an LF.
	 */
	eol_offset = tvb_pbrk_guint8(tvb, offset, len, "\r\n", &found_needle);
	if (eol_offset == -1) {
		/*
		 * No CR or LF - line is presumably continued in next packet.
		 */
		if (desegment) {
			/*
			 * Tell our caller we saw no EOL, so they can
			 * try to desegment and get the entire line
			 * into one tvbuff.
			 */
			return -1;
		} else {
			/*
			 * Pretend the line runs to the end of the tvbuff.
			 */
			linelen = eob_offset - offset;
			if (next_offset)
				*next_offset = eob_offset;
		}
	} else {
		/*
		 * Find the number of bytes between the starting offset
		 * and the CR or LF.
		 */
		linelen = eol_offset - offset;

		/*
		 * Is it a CR?
		 */
		if (found_needle == '\r') {
			/*
			 * Yes - is it followed by an LF?
			 */
			if (eol_offset + 1 >= eob_offset) {
				/*
				 * Dunno - the next byte isn't in this
				 * tvbuff.
				 */
				if (desegment) {
					/*
					 * We'll return -1, although that
					 * runs the risk that if the line
					 * really *is* terminated with a CR,
					 * we won't properly dissect this
					 * tvbuff.
					 *
					 * It's probably more likely that
					 * the line ends with CR-LF than
					 * that it ends with CR by itself.
					 */
					return -1;
				}
			} else {
				/*
				 * Well, we can at least look at the next
				 * byte.
				 */
				if (tvb_get_guint8(tvb, eol_offset + 1) == '\n') {
					/*
					 * It's an LF; skip over the CR.
					 */
					eol_offset++;
				}
			}
		}

		/*
		 * Return the offset of the character after the last
		 * character in the line, skipping over the last character
		 * in the line terminator.
		 */
		if (next_offset)
			*next_offset = eol_offset + 1;
	}
	return linelen;
}

/*
 * Given a tvbuff, an offset into the tvbuff, and a length that starts
 * at that offset (which may be -1 for "all the way to the end of the
 * tvbuff"), find the end of the (putative) line that starts at the
 * specified offset in the tvbuff, going no further than the specified
 * length.
 *
 * However, treat quoted strings inside the buffer specially - don't
 * treat newlines in quoted strings as line terminators.
 *
 * Return the length of the line (not counting the line terminator at
 * the end), or the amount of data remaining in the buffer if we don't
 * find a line terminator.
 *
 * Set "*next_offset" to the offset of the character past the line
 * terminator, or past the end of the buffer if we don't find a line
 * terminator.
 */
gint
tvb_find_line_end_unquoted(tvbuff_t *tvb, const gint offset, int len, gint *next_offset)
{
	gint     cur_offset, char_offset;
	gboolean is_quoted;
	guchar   c = 0;
	gint     eob_offset;
	int      linelen;

	if (len == -1)
		len = tvb_length_remaining(tvb, offset);
	/*
	 * XXX - what if "len" is still -1, meaning "offset is past the
	 * end of the tvbuff"?
	 */
	eob_offset = offset + len;

	cur_offset = offset;
	is_quoted  = FALSE;
	for (;;) {
			/*
		 * Is this part of the string quoted?
		 */
		if (is_quoted) {
			/*
			 * Yes - look only for the terminating quote.
			 */
			char_offset = tvb_find_guint8(tvb, cur_offset, len,
				'"');
		} else {
			/*
			 * Look either for a CR, an LF, or a '"'.
			 */
			char_offset = tvb_pbrk_guint8(tvb, cur_offset, len, "\r\n\"", &c);
		}
		if (char_offset == -1) {
			/*
			 * Not found - line is presumably continued in
			 * next packet.
			 * We pretend the line runs to the end of the tvbuff.
			 */
			linelen = eob_offset - offset;
			if (next_offset)
				*next_offset = eob_offset;
			break;
		}

		if (is_quoted) {
			/*
			 * We're processing a quoted string.
			 * We only looked for ", so we know it's a ";
			 * as we're processing a quoted string, it's a
			 * closing quote.
			 */
			is_quoted = FALSE;
		} else {
			/*
			 * OK, what is it?
			 */
			if (c == '"') {
				/*
				 * Un-quoted "; it begins a quoted
				 * string.
				 */
				is_quoted = TRUE;
			} else {
				/*
				 * It's a CR or LF; we've found a line
				 * terminator.
				 *
				 * Find the number of bytes between the
				 * starting offset and the CR or LF.
				 */
				linelen = char_offset - offset;

				/*
				 * Is it a CR?
				 */
				if (c == '\r') {
					/*
					 * Yes; is it followed by an LF?
					 */
					if (char_offset + 1 < eob_offset &&
						tvb_get_guint8(tvb, char_offset + 1)
						  == '\n') {
						/*
						 * Yes; skip over the CR.
						 */
						char_offset++;
					}
				}

				/*
				 * Return the offset of the character after
				 * the last character in the line, skipping
				 * over the last character in the line
				 * terminator, and quit.
				 */
				if (next_offset)
					*next_offset = char_offset + 1;
				break;
			}
		}

		/*
		 * Step past the character we found.
		 */
		cur_offset = char_offset + 1;
		if (cur_offset >= eob_offset) {
			/*
			 * The character we found was the last character
			 * in the tvbuff - line is presumably continued in
			 * next packet.
			 * We pretend the line runs to the end of the tvbuff.
			 */
			linelen = eob_offset - offset;
			if (next_offset)
				*next_offset = eob_offset;
			break;
		}
	}
	return linelen;
}

/*
 * Copied from the mgcp dissector. (This function should be moved to /epan )
 * tvb_skip_wsp - Returns the position in tvb of the first non-whitespace
 *				  character following offset or offset + maxlength -1 whichever
 *				  is smaller.
 *
 * Parameters:
 * tvb - The tvbuff in which we are skipping whitespace.
 * offset - The offset in tvb from which we begin trying to skip whitespace.
 * maxlength - The maximum distance from offset that we may try to skip
 * whitespace.
 *
 * Returns: The position in tvb of the first non-whitespace
 *			character following offset or offset + maxlength -1 whichever
 *			is smaller.
 */
gint
tvb_skip_wsp(tvbuff_t *tvb, const gint offset, const gint maxlength)
{
	gint   counter = offset;
	gint   end, tvb_len;
	guint8 tempchar;

	/* Get the length remaining */
	tvb_len = tvb_length(tvb);
	end     = offset + maxlength;
	if (end >= tvb_len)
	{
		end = tvb_len;
	}

	/* Skip past spaces, tabs, CRs and LFs until run out or meet something else */
	for (counter = offset;
		 counter < end &&
		  ((tempchar = tvb_get_guint8(tvb,counter)) == ' ' ||
		  tempchar == '\t' || tempchar == '\r' || tempchar == '\n');
		 counter++);

	return (counter);
}

gint
tvb_skip_wsp_return(tvbuff_t *tvb, const gint offset) {
	gint   counter = offset;
	gint   end;
	guint8 tempchar;
	end    = 0;

	for(counter = offset; counter > end &&
		((tempchar = tvb_get_guint8(tvb,counter)) == ' ' ||
		tempchar == '\t' || tempchar == '\n' || tempchar == '\r'); counter--);
	counter++;
	return (counter);
}


/*
 * Format a bunch of data from a tvbuff as bytes, returning a pointer
 * to the string with the formatted data, with "punct" as a byte
 * separator.
 */
gchar *
tvb_bytes_to_str_punct(tvbuff_t *tvb, const gint offset, const gint len, const gchar punct)
{
	return bytes_to_str_punct(ensure_contiguous(tvb, offset, len), len, punct);
}


/*
 * Given a tvbuff, an offset into the tvbuff, and a length that starts
 * at that offset (which may be -1 for "all the way to the end of the
 * tvbuff"), fetch BCD encoded digits from a tvbuff starting from either
 * the low or high half byte, formating the digits according to an input digit set,
 * if NUll a default digit set of 0-9 returning "?" for overdecadic digits will be used.
 * A pointer to the EP allocated string will be returned.
 * Note a tvbuff content of 0xf is considered a 'filler' and will end the conversion.
 */
static dgt_set_t Dgt1_9_bcd = {
	{
		/*  0   1   2   3   4   5   6   7   8   9   a   b   c   d   e */
		'0','1','2','3','4','5','6','7','8','9','?','?','?','?','?'
	}
};
const gchar *
tvb_bcd_dig_to_ep_str(tvbuff_t *tvb, const gint offset, const gint len, dgt_set_t *dgt, gboolean skip_first)
{
	int     length;
	guint8  octet;
	int     i        = 0;
	char   *digit_str;
	gint    t_offset = offset;

	if (!dgt)
		dgt = &Dgt1_9_bcd;

	if (len == -1) {
		length = tvb_length(tvb);
		if (length < offset) {
			return "";
		}
	} else {
		length = offset + len;
	}
	digit_str = ep_alloc((length - offset)*2+1);

	while (t_offset < length) {

		octet = tvb_get_guint8(tvb,t_offset);
		if (!skip_first) {
			digit_str[i] = dgt->out[octet & 0x0f];
			i++;
		}
		skip_first = FALSE;

		/*
		 * unpack second value in byte
		 */
		octet = octet >> 4;

		if (octet == 0x0f)	/* odd number bytes - hit filler */
			break;

		digit_str[i] = dgt->out[octet & 0x0f];
		i++;
		t_offset++;

	}
	digit_str[i]= '\0';
	return digit_str;

}

/*
 * Format a bunch of data from a tvbuff as bytes, returning a pointer
 * to the string with the formatted data.
 */
gchar *
tvb_bytes_to_str(tvbuff_t *tvb, const gint offset, const gint len)
{
	return bytes_to_str(ensure_contiguous(tvb, offset, len), len);
}

/* Find a needle tvbuff within a haystack tvbuff. */
gint
tvb_find_tvb(tvbuff_t *haystack_tvb, tvbuff_t *needle_tvb, const gint haystack_offset)
{
	guint	      haystack_abs_offset, haystack_abs_length;
	const guint8 *haystack_data;
	const guint8 *needle_data;
	const guint   needle_len = needle_tvb->length;
	const guint8 *location;

	DISSECTOR_ASSERT(haystack_tvb && haystack_tvb->initialized);

	if (haystack_tvb->length < 1 || needle_tvb->length < 1) {
		return -1;
	}

	/* Get pointers to the tvbuffs' data. */
	haystack_data = ensure_contiguous(haystack_tvb, 0, -1);
	needle_data   = ensure_contiguous(needle_tvb, 0, -1);

	check_offset_length(haystack_tvb, haystack_offset, -1,
			&haystack_abs_offset, &haystack_abs_length);

	location = epan_memmem(haystack_data + haystack_abs_offset, haystack_abs_length,
			needle_data, needle_len);

	if (location) {
		return (gint) (location - haystack_data);
	}

	return -1;
}

#ifdef HAVE_LIBZ
/*
 * Uncompresses a zlib compressed packet inside a message of tvb at offset with
 * length comprlen.  Returns an uncompressed tvbuffer if uncompression
 * succeeded or NULL if uncompression failed.
 */
#define TVB_Z_MIN_BUFSIZ 32768
#define TVB_Z_MAX_BUFSIZ 1048576 * 10
/* #define TVB_Z_DEBUG 1 */
#undef TVB_Z_DEBUG

tvbuff_t *
tvb_uncompress(tvbuff_t *tvb, const int offset, int comprlen)
{
	gint       err            = Z_OK;
	guint      bytes_out      = 0;
	guint8    *compr          = NULL;
	guint8    *uncompr        = NULL;
	tvbuff_t  *uncompr_tvb    = NULL;
	z_streamp  strm           = NULL;
	Bytef     *strmbuf        = NULL;
	guint      inits_done     = 0;
	gint       wbits          = MAX_WBITS;
	guint8    *next           = NULL;
	guint      bufsiz         = TVB_Z_MIN_BUFSIZ;
#ifdef TVB_Z_DEBUG
	guint      inflate_passes = 0;
	guint      bytes_in       = tvb_length_remaining(tvb, offset);
#endif

	if (tvb == NULL) {
		return NULL;
	}

	compr = tvb_memdup(tvb, offset, comprlen);

	if (!compr)
		return NULL;

	/*
	 * Assume that the uncompressed data is at least twice as big as
	 * the compressed size.
	 */
	bufsiz = tvb_length_remaining(tvb, offset) * 2;
	bufsiz = CLAMP(bufsiz, TVB_Z_MIN_BUFSIZ, TVB_Z_MAX_BUFSIZ);

#ifdef TVB_Z_DEBUG
	printf("bufsiz: %u bytes\n", bufsiz);
#endif

	next = compr;

	strm            = g_new0(z_stream, 1);
	strm->next_in   = next;
	strm->avail_in  = comprlen;

	strmbuf         = g_malloc0(bufsiz);
	strm->next_out  = strmbuf;
	strm->avail_out = bufsiz;

	err = inflateInit2(strm, wbits);
	inits_done = 1;
	if (err != Z_OK) {
		inflateEnd(strm);
		g_free(strm);
		g_free(compr);
		g_free(strmbuf);
		return NULL;
	}

	while (1) {
		memset(strmbuf, '\0', bufsiz);
		strm->next_out  = strmbuf;
		strm->avail_out = bufsiz;

		err = inflate(strm, Z_SYNC_FLUSH);

		if (err == Z_OK || err == Z_STREAM_END) {
			guint bytes_pass = bufsiz - strm->avail_out;

#ifdef TVB_Z_DEBUG
			++inflate_passes;
#endif

			if (uncompr == NULL) {
				/*
				 * This is ugly workaround for bug #6480
				 * (https://bugs.wireshark.org/bugzilla/show_bug.cgi?id=6480)
				 *
				 * g_memdup(..., 0) returns NULL (g_malloc(0) also)
				 * when uncompr is NULL logic below doesn't create tvb
				 * which is later interpreted as decompression failed.
				 */
				uncompr = (bytes_pass || err != Z_STREAM_END) ?
						g_memdup(strmbuf, bytes_pass) :
						g_strdup("");
			} else {
				guint8 *new_data = g_malloc0(bytes_out + bytes_pass);

				memcpy(new_data, uncompr, bytes_out);
				memcpy(new_data + bytes_out, strmbuf, bytes_pass);

				g_free(uncompr);
				uncompr = new_data;
			}

			bytes_out += bytes_pass;

			if (err == Z_STREAM_END) {
				inflateEnd(strm);
				g_free(strm);
				g_free(strmbuf);
				break;
			}
		} else if (err == Z_BUF_ERROR) {
			/*
			 * It's possible that not enough frames were captured
			 * to decompress this fully, so return what we've done
			 * so far, if any.
			 */
			inflateEnd(strm);
			g_free(strm);
			g_free(strmbuf);

			if (uncompr != NULL) {
				break;
			} else {
				g_free(compr);
				return NULL;
			}

		} else if (err == Z_DATA_ERROR && inits_done == 1
			&& uncompr == NULL && (*compr  == 0x1f) &&
			(*(compr + 1) == 0x8b)) {
			/*
			 * inflate() is supposed to handle both gzip and deflate
			 * streams automatically, but in reality it doesn't
			 * seem to handle either (at least not within the
			 * context of an HTTP response.)  We have to try
			 * several tweaks, depending on the type of data and
			 * version of the library installed.
			 */

			/*
			 * Gzip file format.  Skip past the header, since the
			 * fix to make it work (setting windowBits to 31)
			 * doesn't work with all versions of the library.
			 */
			Bytef *c     = compr + 2;
			Bytef  flags = 0;

			if (*c == Z_DEFLATED) {
				c++;
			} else {
				inflateEnd(strm);
				g_free(strm);
				g_free(compr);
				g_free(strmbuf);
				return NULL;
			}

			flags = *c;

			/* Skip past the MTIME, XFL, and OS fields. */
			c += 7;

			if (flags & (1 << 2)) {
				/* An Extra field is present. */
				gint xsize = (gint)(*c |
					(*(c + 1) << 8));

				c += xsize;
			}

			if (flags & (1 << 3)) {
				/* A null terminated filename */

				while ((c - compr) < comprlen && *c != '\0') {
					c++;
				}

				c++;
			}

			if (flags & (1 << 4)) {
				/* A null terminated comment */

				while ((c - compr) < comprlen && *c != '\0') {
					c++;
				}

				c++;
			}


			inflateReset(strm);
			next = c;
			strm->next_in = next;
			if (c - compr > comprlen) {
				inflateEnd(strm);
				g_free(strm);
				g_free(compr);
				g_free(strmbuf);
				return NULL;
			}
			comprlen -= (int) (c - compr);

			inflateEnd(strm);
			inflateInit2(strm, wbits);
			inits_done++;
		} else if (err == Z_DATA_ERROR && uncompr == NULL &&
			inits_done <= 3) {

			/*
			 * Re-init the stream with a negative
			 * MAX_WBITS. This is necessary due to
			 * some servers (Apache) not sending
			 * the deflate header with the
			 * content-encoded response.
			 */
			wbits = -MAX_WBITS;

			inflateReset(strm);

			strm->next_in   = next;
			strm->avail_in  = comprlen;

			inflateEnd(strm);
			memset(strmbuf, '\0', bufsiz);
			strm->next_out  = strmbuf;
			strm->avail_out = bufsiz;

			err = inflateInit2(strm, wbits);

			inits_done++;

			if (err != Z_OK) {
				g_free(strm);
				g_free(strmbuf);
				g_free(compr);
				g_free(uncompr);

				return NULL;
			}
		} else {
			inflateEnd(strm);
			g_free(strm);
			g_free(strmbuf);

			if (uncompr == NULL) {
				g_free(compr);
				return NULL;
			}

			break;
		}
	}

#ifdef TVB_Z_DEBUG
	printf("inflate() total passes: %u\n", inflate_passes);
	printf("bytes  in: %u\nbytes out: %u\n\n", bytes_in, bytes_out);
#endif

	if (uncompr != NULL) {
		uncompr_tvb =  tvb_new_real_data((guint8*) uncompr, bytes_out, bytes_out);
		tvb_set_free_cb(uncompr_tvb, g_free);
	}
	g_free(compr);
	return uncompr_tvb;
}
#else
tvbuff_t *
tvb_uncompress(tvbuff_t *tvb _U_, const int offset _U_, int comprlen _U_)
{
	return NULL;
}
#endif

tvbuff_t *
tvb_child_uncompress(tvbuff_t *parent, tvbuff_t *tvb, const int offset, int comprlen)
{
	tvbuff_t *new_tvb = tvb_uncompress(tvb, offset, comprlen);
	if (new_tvb)
		tvb_set_child_real_data_tvbuff (parent, new_tvb);
	return new_tvb;
}

gint
tvb_raw_offset(tvbuff_t *tvb)
{
	return ((tvb->raw_offset==-1)?(tvb->raw_offset = tvb_offset_from_real_beginning(tvb)):tvb->raw_offset);
}

struct tvbuff *
tvb_get_ds_tvb(tvbuff_t *tvb)
{
	return(tvb->ds_tvb);
}