2003-12-24 02:06:26 +00:00
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/* packet-image-gif.c
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*
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* Routines for image/gif media dissection
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2004-03-08 22:03:59 +00:00
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* Copyright 2003, 2004, Olivier Biot.
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2003-12-24 02:06:26 +00:00
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*
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2004-07-18 00:24:25 +00:00
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* $Id$
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2004-03-08 22:03:59 +00:00
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*
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* Refer to the AUTHORS file or the AUTHORS section in the man page
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* for contacting the author(s) of this file.
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2003-12-24 02:06:26 +00:00
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*
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2006-05-21 04:49:01 +00:00
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* Wireshark - Network traffic analyzer
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* By Gerald Combs <gerald@wireshark.org>
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2003-12-24 02:06:26 +00:00
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* Copyright 1998 Gerald Combs
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*
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* Compuserve GIF media decoding functionality provided by Olivier Biot.
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*
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* The two GIF specifications are found at several locations, such as W3C:
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* http://www.w3.org/Graphics/GIF/spec-gif87.txt
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* http://www.w3.org/Graphics/GIF/spec-gif89a.txt
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*/
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/* Edit this file with 4-space tabulation */
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#ifdef HAVE_CONFIG_H
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# include "config.h"
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#endif
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <glib.h>
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#include <epan/packet.h>
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/* General-purpose debug logger.
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* Requires double parentheses because of variable arguments of printf().
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*
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* Enable debug logging for GIF by defining AM_CFLAGS
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* so that it contains "-DDEBUG_image_gif" or "-DDEBUG_image"
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*/
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#if (defined(DEBUG_image_gif) || defined(DEBUG_image))
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#define DebugLog(x) \
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2005-11-01 18:18:46 +00:00
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g_print("%s:%u: ", __FILE__, __LINE__); \
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g_print x
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2003-12-24 02:06:26 +00:00
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#else
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#define DebugLog(x) ;
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#endif
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#define IMG_GIF "image-gif"
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/************************** Variable declarations **************************/
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static const value_string vals_true_false[] = {
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{ 0, "False" },
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{ 1, "True" },
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{ 0, NULL },
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};
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static const value_string vals_extensions[] = {
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{ 0xF9, "Graphics Control" },
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{ 0xFE, "Comment" },
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{ 0xFF, "Application" },
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{ 0x01, "Plain Text" },
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{ 0x00, NULL, },
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};
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enum {
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GIF_UNKNOWN = 0,
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GIF_87a = 0x87,
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GIF_89a = 0x89,
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GIF_ERROR = 0xFF
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};
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/* Initialize the protocol and registered fields */
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static int proto_gif = -1;
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/* header fields */
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/* GIF signature */
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static gint hf_version = -1;
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/* Screen descriptor */
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static gint hf_screen_width = -1;
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static gint hf_screen_height = -1;
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static gint hf_global_color_map_present = -1;
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static gint hf_global_color_resolution = -1;
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static gint hf_global_color_map_ordered = -1; /* GIF89a */
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static gint hf_global_image_bpp = -1;
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/* Only makes sense if the global color map is present: */
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static gint hf_background_color = -1;
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static gint hf_pixel_aspect_ratio = -1; /* GIF89a */
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static gint hf_global_color_map = -1;
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/* Image descriptor */
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static gint hf_image_left = -1;
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static gint hf_image_top = -1;
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static gint hf_image_width = -1;
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static gint hf_image_height = -1;
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static gint hf_local_color_map_present = -1;
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static gint hf_local_color_resolution = -1;
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static gint hf_local_color_map_ordered = -1; /* GIF89a */
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static gint hf_local_image_bpp = -1;
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static gint hf_local_color_map = -1;
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static gint hf_extension = -1;
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static gint hf_extension_label = -1;
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static gint hf_image = -1;
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static gint hf_image_code_size = -1;
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/* Trailer (end of GIF data stream) */
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static gint hf_trailer = -1;
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/* Initialize the subtree pointers */
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static gint ett_gif = -1;
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static gint ett_global_flags = -1;
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static gint ett_local_flags = -1;
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static gint ett_extension = -1;
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static gint ett_image = -1;
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/**************** GIF related declarations and definitions ****************/
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/************************** Function prototypes **************************/
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static void
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dissect_gif(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree);
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void
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proto_register_gif(void);
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/****************** GIF protocol dissection functions ******************/
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/* There are two Compuserve GIF standards: GIF87a and GIF89a. GIF image files
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* always convey their version in the first 6 bytes, written as an US-ASCII
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* string representation of the version: "GIF87a" or "GIF89a".
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*/
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static void
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dissect_gif(tvbuff_t *tvb, packet_info *pinfo _U_, proto_tree *tree)
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{
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proto_item *ti;
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proto_tree *gif_tree; /* Main GIF tree */
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proto_tree *subtree; /* Main GIF tree */
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guint offset = 0, len = 0;
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guint8 peek;
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gboolean color_map_present;
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guint8 color_resolution;
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guint8 image_bpp;
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guint tvb_len = tvb_reported_length(tvb);
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2007-03-27 22:50:11 +00:00
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char *str = (char*)tvb_get_ephemeral_string(tvb, 0, 6);
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2003-12-24 02:06:26 +00:00
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guint8 version;
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/* Check whether we're processing a GIF object */
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if (strcmp(str, "GIF87a") == 0) {
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version = GIF_87a;
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} else if (strcmp(str, "GIF89a") == 0) {
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version = GIF_89a;
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} else if (strncmp(str,"GIF", 3) == 0) {
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version = GIF_UNKNOWN;
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} else {
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/* Not a GIF image! */
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version = GIF_ERROR;
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return;
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}
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/* Add summary to INFO column if it is enabled */
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if (check_col(pinfo->cinfo, COL_INFO))
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col_append_fstr(pinfo->cinfo, COL_INFO, " (%s)", str);
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/* In order to speed up dissection, do not add items to the protocol tree
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* if it is not visible. However, compute the values that are needed for
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* correct protocol dissection if they have more meaning than just adding
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* items to the protocol tree.
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*/
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if (tree) {
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ti = proto_tree_add_item(tree, proto_gif, tvb, 0, -1, TRUE);
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proto_item_append_text(ti, ", Version: %s", str);
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gif_tree = proto_item_add_subtree(ti, ett_gif);
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/* GIF signature */
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ti = proto_tree_add_item(gif_tree, hf_version, tvb, 0, 6, TRUE);
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if (version == GIF_UNKNOWN) {
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proto_item_append_text(ti, " <Error: unknown GIF version>");
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}
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/* Screen descriptor */
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proto_tree_add_item(gif_tree, hf_screen_width, tvb, 6, 2, TRUE);
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proto_tree_add_item(gif_tree, hf_screen_height, tvb, 8, 2, TRUE);
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peek = tvb_get_guint8(tvb, 10);
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/* Bitfield gccc 0ppp
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* g... .... : global color map present
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* .ccc .... : color resolution in bits (add one)
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* .... 0... : GIF87a - reserved (no use)
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* GIF89a - ordered (most important color 1st)
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* .... .ppp : bits per pixel in image (add one)
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*/
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color_map_present = peek & 0x80;
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color_resolution = 1 + ((peek & 0x60) >> 4);
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image_bpp = 1 + (peek & 0x07);
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ti = proto_tree_add_text(gif_tree, tvb, 10, 1,
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"Global settings:");
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if (color_map_present)
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proto_item_append_text(ti, " (Global color table present)");
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proto_item_append_text(ti,
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" (%u bit%s per color) (%u bit%s per pixel)",
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2004-12-20 22:13:48 +00:00
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color_resolution, plurality(color_resolution, "", "s"),
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image_bpp, plurality(image_bpp, "", "s"));
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2003-12-24 02:06:26 +00:00
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subtree = proto_item_add_subtree(ti, ett_global_flags);
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proto_tree_add_item(subtree, hf_global_color_map_present,
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tvb, 10, 1, TRUE);
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proto_tree_add_item(subtree, hf_global_color_resolution,
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tvb, 10, 1, TRUE);
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if (version == GIF_89a) {
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proto_tree_add_item(subtree, hf_global_color_map_ordered,
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tvb, 10, 1, TRUE);
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}
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proto_tree_add_item(subtree, hf_global_image_bpp,
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tvb, 10, 1, TRUE);
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/* Background color */
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proto_tree_add_item(gif_tree, hf_background_color,
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tvb, 11, 1, TRUE);
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/* byte at offset 12 is 0x00 - reserved in GIF87a but encodes the
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* pixel aspect ratio in GIF89a as:
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* aspect-ratio = (15 + pixel-aspect-ratio) / 64
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* where the aspect-ratio is not computed if pixel-aspect-ratio == 0
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*/
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if (version == GIF_89a) {
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peek = tvb_get_guint8(tvb, 12);
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if (peek) {
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/* Only display if different from 0 */
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proto_tree_add_uint_format(gif_tree, hf_pixel_aspect_ratio,
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tvb, 12, 1, peek,
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"%u, yields an aspect ratio of (15 + %u) / 64 = %.2f",
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peek, peek, (float)(15 + peek) / 64.0);
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}
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}
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/* Global color map
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* If present, it takes 2 ^ (image_bpp) byte tuples (R, G, B)
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* that contain the Red, Green and Blue intensity of the colors
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* in the Global Color Map */
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if (color_map_present) {
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len = 3 * (1 << image_bpp);
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proto_tree_add_item(gif_tree, hf_global_color_map,
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tvb, 13, len, TRUE);
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} else {
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len = 0;
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}
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offset = 13 + len;
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/* From now on, a set of images prefixed with the image separator
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* character 0x2C (',') will appear in the byte stream. Each image
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* hence consists of:
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* - The image separator character 0x2C
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* - Image left (16 bits LSB first): pixels from left border
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* - Image top (16 bits LSB first): pixels from to border
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* - Image width (16 bits LSB first)
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* - Image height (16 bits LSB first)
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* - A bitfield MI00 0ppp
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* M... .... : Use global color map if unset (ignore ppp);
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* if set a local color map will be defined.
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* .I.. .... : Image formatted in interlaced order if set;
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* otherwise it is plain sequential order
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* ..0. .... : GIF87a - Reserved
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* ..s. .... GIF89a - Set if local color map is ordered
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* ...0 0... : Reserved
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* .... .ppp : bits per pixel in image (add one)
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* - If the local color map bit is set, then a local color table follows
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* with length = 3 x 2 ^ (1 + bits per pixel)
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* - The raster data
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*
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* NOTE that the GIF specification only requires that:
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* image left + image width <= screen width
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* image top + image height <= screen height
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*
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* The Raster Data is encoded as follows:
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* - Code size (1 byte)
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* - Blocks consisting of
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* o Byte count (1 byte): number of bytes in the block
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* o Data bytes: as many as specified in the byte count
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* End of data is given with an empty block (byte count == 0).
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*
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*
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* GIF terminator
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* This is a synchronization method, based on the final character 0xB3
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* (';') at the end of an image
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*
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*
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* GIF extension
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* This is a block of data encoded as:
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* - The GIF extension block introducer 0x21 ('!')
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* - The extension function code (1 byte)
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* - Blocks consisting of
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* o Byte count (1 byte): number of bytes in the block
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* o Data bytes: as many as specified in the byte count
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* End of data is given with an empty block (byte count == 0).
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*
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* NOTE that the GIF extension block can only appear at the following
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* locations:
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* - Immediately before an Image Descriptor
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* - Before the GIF termination character
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*/
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while (offset < tvb_len) {
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peek = tvb_get_guint8(tvb, offset);
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if (peek == 0x21) { /* GIF extension block */
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2003-12-24 12:46:57 +00:00
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guint32 item_len = 2; /* Fixed header consisting of:
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* 1 byte : 0x21
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* 1 byte : extension_label
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*/
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2003-12-24 02:06:26 +00:00
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ti = proto_tree_add_item(gif_tree, hf_extension,
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tvb, offset, 1, TRUE);
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subtree = proto_item_add_subtree(ti, ett_extension);
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offset++;
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proto_tree_add_item(subtree, hf_extension_label,
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tvb, offset, 1, TRUE);
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peek = tvb_get_guint8(tvb, offset);
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proto_item_append_text(ti, ": %s",
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val_to_str(peek, vals_extensions,
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"<Warning: Unknown extension 0x%02X>"));
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offset++;
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do {
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|
|
/* Read length of data block */
|
|
|
|
len = tvb_get_guint8(tvb, offset);
|
|
|
|
proto_tree_add_text(subtree, tvb,
|
|
|
|
offset, 1 + len,
|
|
|
|
"Data block (length = %u)", len);
|
|
|
|
offset += (1 + len);
|
|
|
|
item_len += (1 + len);
|
|
|
|
} while (len > 0);
|
|
|
|
proto_item_set_len(ti, item_len);
|
|
|
|
} else if (peek == 0x2C) { /* Image separator */
|
|
|
|
proto_tree *subtree2;
|
|
|
|
proto_item *ti2;
|
2003-12-24 12:46:57 +00:00
|
|
|
guint32 item_len = 11; /* Fixed header consisting of:
|
|
|
|
* 1 byte : 0x2C
|
|
|
|
* 2 bytes: image_left
|
|
|
|
* 2 bytes: image_top
|
|
|
|
* 2 bytes: image_width
|
|
|
|
* 2 bytes: image height
|
|
|
|
* 1 byte : packed bit field
|
|
|
|
* 1 byte : image code size
|
|
|
|
*/
|
2003-12-24 02:06:26 +00:00
|
|
|
|
|
|
|
ti = proto_tree_add_item(gif_tree, hf_image,
|
|
|
|
tvb, offset, 1, TRUE);
|
|
|
|
subtree = proto_item_add_subtree(ti, ett_image);
|
|
|
|
offset++;
|
|
|
|
/* Screen descriptor */
|
|
|
|
proto_tree_add_item(subtree, hf_image_left,
|
|
|
|
tvb, offset, 2, TRUE); offset += 2;
|
|
|
|
proto_tree_add_item(subtree, hf_image_top,
|
|
|
|
tvb, offset, 2, TRUE); offset += 2;
|
|
|
|
proto_tree_add_item(subtree, hf_image_width,
|
|
|
|
tvb, offset, 2, TRUE); offset += 2;
|
|
|
|
proto_tree_add_item(subtree, hf_image_height,
|
|
|
|
tvb, offset, 2, TRUE); offset += 2;
|
|
|
|
/* bit field */
|
|
|
|
peek = tvb_get_guint8(tvb, offset);
|
|
|
|
color_map_present = peek & 0x80;
|
|
|
|
color_resolution = 1 + ((peek & 0x60) >> 4);
|
|
|
|
image_bpp = 1 + (peek & 0x07);
|
|
|
|
|
|
|
|
ti2 = proto_tree_add_text(subtree, tvb, offset, 1,
|
|
|
|
"Local settings:");
|
|
|
|
if (color_map_present)
|
|
|
|
proto_item_append_text(ti2, " (Local color table present)");
|
|
|
|
proto_item_append_text(ti2,
|
|
|
|
" (%u bit%s per color) (%u bit%s per pixel)",
|
2004-12-20 22:13:48 +00:00
|
|
|
color_resolution, plurality(color_resolution, "", "s"),
|
|
|
|
image_bpp, plurality(image_bpp, "", "s"));
|
2003-12-24 02:06:26 +00:00
|
|
|
subtree2 = proto_item_add_subtree(ti2, ett_local_flags);
|
|
|
|
proto_tree_add_item(subtree2, hf_local_color_map_present,
|
|
|
|
tvb, offset, 1, TRUE);
|
|
|
|
proto_tree_add_item(subtree2, hf_local_color_resolution,
|
|
|
|
tvb, offset, 1, TRUE);
|
|
|
|
if (version == GIF_89a) {
|
|
|
|
proto_tree_add_item(subtree2, hf_local_color_map_ordered,
|
|
|
|
tvb, offset, 1, TRUE);
|
|
|
|
}
|
|
|
|
proto_tree_add_item(subtree2, hf_global_image_bpp,
|
|
|
|
tvb, offset, 1, TRUE);
|
|
|
|
offset++;
|
|
|
|
|
|
|
|
/* Local color map
|
|
|
|
* If present, it takes 2 ^ (image_bpp) byte tuples (R, G, B)
|
|
|
|
* that contain the Red, Green and Blue intensity of the colors
|
|
|
|
* in the Local Color Map */
|
|
|
|
if (color_map_present) {
|
|
|
|
len = 3 * (1 << image_bpp);
|
|
|
|
proto_tree_add_item(subtree, hf_local_color_map,
|
|
|
|
tvb, offset, len, TRUE);
|
|
|
|
} else {
|
|
|
|
len = 0;
|
|
|
|
}
|
|
|
|
offset += len;
|
|
|
|
item_len += len;
|
|
|
|
|
|
|
|
proto_tree_add_item(subtree, hf_image_code_size,
|
|
|
|
tvb, offset, 1, TRUE);
|
|
|
|
offset++;
|
|
|
|
do {
|
|
|
|
/* Read length of data block */
|
|
|
|
len = tvb_get_guint8(tvb, offset);
|
|
|
|
proto_tree_add_text(subtree, tvb,
|
|
|
|
offset, 1 + len,
|
|
|
|
"Data block (length = %u)", len);
|
|
|
|
offset += 1 + len;
|
|
|
|
item_len += (1 + len);
|
|
|
|
} while (len > 0);
|
|
|
|
proto_item_set_len(ti, item_len);
|
|
|
|
} else {
|
|
|
|
/* GIF processing stops at this very byte */
|
|
|
|
proto_tree_add_item(gif_tree, hf_trailer,
|
|
|
|
tvb, offset, 1, TRUE);
|
|
|
|
break;
|
|
|
|
}
|
|
|
|
} /* while */
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
|
2006-05-21 04:49:01 +00:00
|
|
|
/****************** Register the protocol with Wireshark ******************/
|
2003-12-24 02:06:26 +00:00
|
|
|
|
|
|
|
|
|
|
|
/* This format is required because a script is used to build the C function
|
|
|
|
* that calls the protocol registration. */
|
|
|
|
|
|
|
|
void
|
|
|
|
proto_register_gif(void)
|
|
|
|
{
|
|
|
|
/*
|
|
|
|
* Setup list of header fields.
|
|
|
|
*/
|
|
|
|
static hf_register_info hf[] = {
|
|
|
|
/*
|
|
|
|
* GIF signature and version
|
|
|
|
*/
|
|
|
|
{ &hf_version,
|
|
|
|
{ "Version",
|
|
|
|
IMG_GIF ".version",
|
|
|
|
FT_STRING, BASE_NONE, NULL, 0x00,
|
|
|
|
"GIF Version",
|
|
|
|
HFILL
|
|
|
|
}
|
|
|
|
},
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Logical screen descriptor
|
|
|
|
*/
|
|
|
|
{ &hf_screen_width,
|
|
|
|
{ "Screen width",
|
|
|
|
IMG_GIF ".screen.width",
|
|
|
|
FT_UINT16, BASE_DEC, NULL, 0x00,
|
|
|
|
"Screen width",
|
|
|
|
HFILL
|
|
|
|
}
|
|
|
|
},
|
|
|
|
{ &hf_screen_height,
|
|
|
|
{ "Screen height",
|
|
|
|
IMG_GIF ".screen.height",
|
|
|
|
FT_UINT16, BASE_DEC, NULL, 0x00,
|
|
|
|
"Screen height",
|
|
|
|
HFILL
|
|
|
|
}
|
|
|
|
},
|
|
|
|
{ &hf_global_color_map_present,
|
|
|
|
{ "Global color map is present",
|
|
|
|
IMG_GIF ".global.color_map.present",
|
|
|
|
FT_UINT8, BASE_DEC, VALS(vals_true_false), 0x80,
|
|
|
|
"Indicates if the global color map is present",
|
|
|
|
HFILL
|
|
|
|
}
|
|
|
|
},
|
|
|
|
{ &hf_global_color_resolution,
|
|
|
|
{ "Bits per color minus 1",
|
|
|
|
IMG_GIF ".global.color_bpp",
|
|
|
|
FT_UINT8, BASE_DEC, NULL, 0x70,
|
|
|
|
"The number of bits per color is one plus the field value.",
|
|
|
|
HFILL
|
|
|
|
}
|
|
|
|
},
|
|
|
|
{ &hf_global_color_map_ordered,
|
|
|
|
{ "Global color map is ordered",
|
|
|
|
IMG_GIF ".global.color_map.ordered",
|
|
|
|
FT_UINT8, BASE_DEC, VALS(vals_true_false), 0x08,
|
|
|
|
"Indicates whether the global color map is ordered.",
|
|
|
|
HFILL
|
|
|
|
}
|
|
|
|
},
|
|
|
|
{ &hf_global_image_bpp,
|
|
|
|
{ "Image bits per pixel minus 1",
|
|
|
|
IMG_GIF ".global.bpp",
|
|
|
|
FT_UINT8, BASE_DEC, NULL, 0x07,
|
|
|
|
"The number of bits per pixel is one plus the field value.",
|
|
|
|
HFILL
|
|
|
|
}
|
|
|
|
},
|
|
|
|
{ &hf_background_color,
|
|
|
|
{ "Background color index",
|
|
|
|
IMG_GIF ".image_background_index",
|
|
|
|
FT_UINT8, BASE_DEC, NULL, 0x00,
|
|
|
|
"Index of the background color in the color map.",
|
|
|
|
HFILL
|
|
|
|
}
|
|
|
|
},
|
|
|
|
{ &hf_pixel_aspect_ratio,
|
|
|
|
{ "Global pixel aspect ratio",
|
|
|
|
IMG_GIF ".global.pixel_aspect_ratio",
|
|
|
|
FT_UINT8, BASE_DEC, NULL, 0x00,
|
|
|
|
"Gives an approximate value of the aspect ratio of the pixels.",
|
|
|
|
HFILL
|
|
|
|
}
|
|
|
|
},
|
|
|
|
{ &hf_global_color_map,
|
|
|
|
{ "Global color map",
|
|
|
|
IMG_GIF ".global.color_map",
|
|
|
|
FT_BYTES, BASE_NONE, NULL, 0x00,
|
|
|
|
"Global color map.",
|
|
|
|
HFILL
|
|
|
|
}
|
|
|
|
},
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Local color map (part of image)
|
|
|
|
*/
|
|
|
|
{ &hf_local_color_map_present,
|
|
|
|
{ "Local color map is present",
|
|
|
|
IMG_GIF ".local.color_map.present",
|
|
|
|
FT_UINT8, BASE_DEC, VALS(vals_true_false), 0x80,
|
|
|
|
"Indicates if the local color map is present",
|
|
|
|
HFILL
|
|
|
|
}
|
|
|
|
},
|
|
|
|
{ &hf_local_color_resolution,
|
|
|
|
{ "Bits per color minus 1",
|
|
|
|
IMG_GIF ".local.color_bpp",
|
|
|
|
FT_UINT8, BASE_DEC, NULL, 0x70,
|
|
|
|
"The number of bits per color is one plus the field value.",
|
|
|
|
HFILL
|
|
|
|
}
|
|
|
|
},
|
|
|
|
{ &hf_local_color_map_ordered,
|
|
|
|
{ "Local color map is ordered",
|
|
|
|
IMG_GIF ".local.color_map.ordered",
|
|
|
|
FT_UINT8, BASE_DEC, VALS(vals_true_false), 0x08,
|
|
|
|
"Indicates whether the local color map is ordered.",
|
|
|
|
HFILL
|
|
|
|
}
|
|
|
|
},
|
|
|
|
{ &hf_local_image_bpp,
|
|
|
|
{ "Image bits per pixel minus 1",
|
2004-01-03 12:43:51 +00:00
|
|
|
IMG_GIF ".local.bpp",
|
2003-12-24 02:06:26 +00:00
|
|
|
FT_UINT8, BASE_DEC, NULL, 0x07,
|
|
|
|
"The number of bits per pixel is one plus the field value.",
|
|
|
|
HFILL
|
|
|
|
}
|
|
|
|
},
|
|
|
|
{ &hf_local_color_map,
|
|
|
|
{ "Local color map",
|
|
|
|
IMG_GIF ".local.color_map",
|
|
|
|
FT_BYTES, BASE_NONE, NULL, 0x00,
|
|
|
|
"Local color map.",
|
|
|
|
HFILL
|
|
|
|
}
|
|
|
|
},
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Extension
|
|
|
|
*/
|
|
|
|
{ &hf_extension,
|
|
|
|
{ "Extension",
|
|
|
|
IMG_GIF ".extension",
|
|
|
|
FT_NONE, BASE_NONE, NULL, 0x00,
|
|
|
|
"Extension.",
|
|
|
|
HFILL
|
|
|
|
}
|
|
|
|
},
|
|
|
|
{ &hf_extension_label,
|
|
|
|
{ "Extension label",
|
|
|
|
IMG_GIF ".extension.label",
|
|
|
|
FT_UINT8, BASE_HEX, VALS(vals_extensions), 0x00,
|
|
|
|
"Extension label.",
|
|
|
|
HFILL
|
|
|
|
}
|
|
|
|
},
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Image
|
|
|
|
*/
|
|
|
|
{ &hf_image,
|
|
|
|
{ "Image",
|
|
|
|
IMG_GIF ".image",
|
2005-05-28 00:51:56 +00:00
|
|
|
FT_NONE, BASE_NONE, NULL, 0x00,
|
2003-12-24 02:06:26 +00:00
|
|
|
"Image.",
|
|
|
|
HFILL
|
|
|
|
}
|
|
|
|
},
|
|
|
|
{ &hf_image_left,
|
|
|
|
{ "Image left position",
|
|
|
|
IMG_GIF ".image.left",
|
|
|
|
FT_UINT16, BASE_DEC, NULL, 0x00,
|
|
|
|
"Offset between left of Screen and left of Image.",
|
|
|
|
HFILL
|
|
|
|
}
|
|
|
|
},
|
|
|
|
{ &hf_image_top,
|
|
|
|
{ "Image top position",
|
|
|
|
IMG_GIF ".image.top",
|
|
|
|
FT_UINT16, BASE_DEC, NULL, 0x00,
|
|
|
|
"Offset between top of Screen and top of Image.",
|
|
|
|
HFILL
|
|
|
|
}
|
|
|
|
},
|
|
|
|
{ &hf_image_width,
|
|
|
|
{ "Image width",
|
|
|
|
IMG_GIF ".image.width",
|
|
|
|
FT_UINT16, BASE_DEC, NULL, 0x00,
|
|
|
|
"Image width.",
|
|
|
|
HFILL
|
|
|
|
}
|
|
|
|
},
|
|
|
|
{ &hf_image_height,
|
|
|
|
{ "Image height",
|
|
|
|
IMG_GIF ".image.height",
|
|
|
|
FT_UINT16, BASE_DEC, NULL, 0x00,
|
|
|
|
"Image height.",
|
|
|
|
HFILL
|
|
|
|
}
|
|
|
|
},
|
|
|
|
{ &hf_image_code_size,
|
|
|
|
{ "LZW minimum code size",
|
|
|
|
IMG_GIF ".image.code_size",
|
|
|
|
FT_UINT8, BASE_DEC, NULL, 0x00,
|
|
|
|
"Minimum code size for the LZW compression.",
|
|
|
|
HFILL
|
|
|
|
}
|
|
|
|
},
|
|
|
|
/*
|
|
|
|
* Trailer
|
|
|
|
*/
|
|
|
|
{ &hf_trailer,
|
|
|
|
{ "Trailer (End of the GIF stream)",
|
|
|
|
IMG_GIF ".end",
|
|
|
|
FT_NONE, BASE_NONE, NULL, 0x00,
|
|
|
|
"This byte tells the decoder that the data stream is finished.",
|
|
|
|
HFILL
|
|
|
|
}
|
|
|
|
},
|
|
|
|
};
|
|
|
|
|
|
|
|
/* Setup protocol subtree array */
|
|
|
|
static gint *ett[] = {
|
|
|
|
&ett_gif,
|
|
|
|
&ett_global_flags,
|
|
|
|
&ett_local_flags,
|
|
|
|
&ett_extension,
|
|
|
|
&ett_image,
|
|
|
|
};
|
|
|
|
|
|
|
|
/* Register the protocol name and description */
|
|
|
|
proto_gif = proto_register_protocol(
|
|
|
|
"Compuserve GIF",
|
|
|
|
"GIF image",
|
|
|
|
IMG_GIF
|
|
|
|
);
|
|
|
|
|
|
|
|
/* Required function calls to register the header fields
|
|
|
|
* and subtrees used */
|
|
|
|
proto_register_field_array(proto_gif, hf, array_length(hf));
|
|
|
|
proto_register_subtree_array(ett, array_length(ett));
|
|
|
|
|
|
|
|
register_dissector("image-gif", dissect_gif, proto_gif);
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
|
|
void
|
|
|
|
proto_reg_handoff_gif(void)
|
|
|
|
{
|
|
|
|
dissector_handle_t gif_handle;
|
|
|
|
|
|
|
|
gif_handle = create_dissector_handle(dissect_gif, proto_gif);
|
|
|
|
|
|
|
|
/* Register the GIF media type */
|
|
|
|
dissector_add_string("media_type", "image/gif", gif_handle);
|
|
|
|
}
|