![Peter Wu](/assets/img/avatar_default.png)
Change-Id: Idb2e4f9964cf0b5c1237a0d4b5e0954adfd5e6b6 Reviewed-on: https://code.wireshark.org/review/31895 Petri-Dish: Peter Wu <peter@lekensteyn.nl> Tested-by: Petri Dish Buildbot Reviewed-by: Peter Wu <peter@lekensteyn.nl>
501 lines
18 KiB
C
501 lines
18 KiB
C
/* decode_as_utils.c
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*
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* Routines to modify dissector tables on the fly.
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*
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* By David Hampton <dhampton@mac.com>
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* Copyright 2001 David Hampton
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*
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* SPDX-License-Identifier: GPL-2.0-or-later
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*/
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#include "config.h"
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#include <stdlib.h>
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#include <errno.h>
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#include "epan/decode_as.h"
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#include "epan/packet.h"
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#include "epan/prefs.h"
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#include "epan/prefs-int.h"
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#include "ui/decode_as_utils.h"
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#include "ui/simple_dialog.h"
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#include "wsutil/file_util.h"
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#include "wsutil/filesystem.h"
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#include "ui/cmdarg_err.h"
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#include "version_info.h"
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/* XXX - We might want to switch this to a UAT */
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static const char* prev_display_dissector_name = NULL;
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/*
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* For a dissector table, print on the stream described by output,
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* its short name (which is what's used in the "-d" option) and its
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* descriptive name.
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*/
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static void
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display_dissector_table_names(const char *table_name, const char *ui_name,
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gpointer output)
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{
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if ((prev_display_dissector_name == NULL) ||
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(strcmp(prev_display_dissector_name, table_name) != 0)) {
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fprintf((FILE *)output, "\t%s (%s)\n", table_name, ui_name);
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prev_display_dissector_name = table_name;
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}
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}
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/*
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* For a dissector handle, print on the stream described by output,
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* the filter name (which is what's used in the "-d" option) and the full
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* name for the protocol that corresponds to this handle.
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*/
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static void
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display_dissector_names(const gchar *table _U_, gpointer handle, gpointer output)
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{
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int proto_id;
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const gchar *proto_filter_name;
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const gchar *proto_ui_name;
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proto_id = dissector_handle_get_protocol_index((dissector_handle_t)handle);
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if (proto_id != -1) {
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proto_filter_name = proto_get_protocol_filter_name(proto_id);
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proto_ui_name = proto_get_protocol_name(proto_id);
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g_assert(proto_filter_name != NULL);
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g_assert(proto_ui_name != NULL);
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if ((prev_display_dissector_name == NULL) ||
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(strcmp(prev_display_dissector_name, proto_filter_name) != 0)) {
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fprintf((FILE *)output, "\t%s (%s)\n",
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proto_filter_name,
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proto_ui_name);
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prev_display_dissector_name = proto_filter_name;
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}
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}
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}
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/*
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* Allow dissector key names to be sorted alphabetically
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*/
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static gint
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compare_dissector_key_name(gconstpointer dissector_a, gconstpointer dissector_b)
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{
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return strcmp((const char*)dissector_a, (const char*)dissector_b);
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}
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/*
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* Print all layer type names supported.
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* We send the output to the stream described by the handle output.
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*/
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static void
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fprint_all_layer_types(FILE *output)
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{
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prev_display_dissector_name = NULL;
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dissector_all_tables_foreach_table(display_dissector_table_names, (gpointer)output, (GCompareFunc)compare_dissector_key_name);
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}
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/*
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* Print all protocol names supported for a specific layer type.
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* table_name contains the layer type name in which the search is performed.
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* We send the output to the stream described by the handle output.
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*/
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static void
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fprint_all_protocols_for_layer_types(FILE *output, gchar *table_name)
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{
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prev_display_dissector_name = NULL;
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dissector_table_foreach_handle(table_name,
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display_dissector_names,
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(gpointer)output);
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}
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/*
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* The protocol_name_search structure is used by find_protocol_name_func()
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* to pass parameters and store results
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*/
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struct protocol_name_search{
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const char *searched_name; /* Protocol filter name we are looking for */
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dissector_handle_t matched_handle; /* Handle for a dissector whose protocol has the specified filter name */
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guint nb_match; /* How many dissectors matched searched_name */
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};
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typedef struct protocol_name_search *protocol_name_search_t;
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/*
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* This function parses all dissectors associated with a table to find the
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* one whose protocol has the specified filter name. It is called
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* as a reference function in a call to dissector_table_foreach_handle.
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* The name we are looking for, as well as the results, are stored in the
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* protocol_name_search struct pointed to by user_data.
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* If called using dissector_table_foreach_handle, we actually parse the
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* whole list of dissectors.
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*/
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static void
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find_protocol_name_func(const gchar *table _U_, gpointer handle, gpointer user_data)
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{
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int proto_id;
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const gchar *protocol_filter_name;
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protocol_name_search_t search_info;
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g_assert(handle);
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search_info = (protocol_name_search_t)user_data;
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proto_id = dissector_handle_get_protocol_index((dissector_handle_t)handle);
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if (proto_id != -1) {
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protocol_filter_name = proto_get_protocol_filter_name(proto_id);
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g_assert(protocol_filter_name != NULL);
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if (strcmp(protocol_filter_name, search_info->searched_name) == 0) {
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/* Found a match */
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if (search_info->nb_match == 0) {
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/* Record this handle only if this is the first match */
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search_info->matched_handle = (dissector_handle_t)handle; /* Record the handle for this matching dissector */
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}
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search_info->nb_match++;
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}
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}
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}
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/*
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* The function below parses the command-line parameters for the decode as
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* feature (a string pointer by cl_param).
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* It checks the format of the command-line, searches for a matching table
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* and dissector. If a table/dissector match is not found, we display a
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* summary of the available tables/dissectors (on stderr) and return FALSE.
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* If everything is fine, we get the "Decode as" preference activated,
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* then we return TRUE.
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*/
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gboolean decode_as_command_option(const gchar *cl_param)
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{
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gchar *table_name;
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guint32 selector = 0, selector2 = 0;
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gchar *decoded_param;
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gchar *remaining_param;
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gchar *selector_str = NULL;
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gchar *dissector_str;
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dissector_handle_t dissector_matching;
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dissector_table_t table_matching;
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ftenum_t dissector_table_selector_type;
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struct protocol_name_search user_protocol_name;
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guint64 i;
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char op = '\0';
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/* The following code will allocate and copy the command-line options in a string pointed by decoded_param */
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g_assert(cl_param);
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decoded_param = g_strdup(cl_param);
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g_assert(decoded_param);
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/* The lines below will parse this string (modifying it) to extract all
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necessary information. Note that decoded_param is still needed since
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strings are not copied - we just save pointers. */
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/* This section extracts a layer type (table_name) from decoded_param */
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table_name = decoded_param; /* Layer type string starts from beginning */
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remaining_param = strchr(table_name, '=');
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if (remaining_param == NULL) {
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/* Dissector tables of type FT_NONE aren't required to specify a value, so for now
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just check for comma */
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remaining_param = strchr(table_name, ',');
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if (remaining_param == NULL) {
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cmdarg_err("Parameter \"%s\" doesn't follow the template \"%s\"", cl_param, DECODE_AS_ARG_TEMPLATE);
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} else {
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*remaining_param = '\0'; /* Terminate the layer type string (table_name) where ',' was detected */
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}
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/* If the argument does not follow the template, carry on anyway to check
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if the table name is at least correct. If remaining_param is NULL,
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we'll exit anyway further down */
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}
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else {
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*remaining_param = '\0'; /* Terminate the layer type string (table_name) where '=' was detected */
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}
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/* Remove leading and trailing spaces from the table name */
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while (table_name[0] == ' ')
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table_name++;
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while (table_name[strlen(table_name) - 1] == ' ')
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table_name[strlen(table_name) - 1] = '\0'; /* Note: if empty string, while loop will eventually exit */
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/* The following part searches a table matching with the layer type specified */
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table_matching = NULL;
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/* Look for the requested table */
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if (!(*(table_name))) { /* Is the table name empty, if so, don't even search for anything, display a message */
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cmdarg_err("No layer type specified"); /* Note, we don't exit here, but table_matching will remain NULL, so we exit below */
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}
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else {
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table_matching = find_dissector_table(table_name);
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if (!table_matching) {
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cmdarg_err("Unknown layer type -- %s", table_name); /* Note, we don't exit here, but table_matching will remain NULL, so we exit below */
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}
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}
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if (!table_matching) {
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/* Display a list of supported layer types to help the user, if the
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specified layer type was not found */
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cmdarg_err("Valid layer types are:");
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fprint_all_layer_types(stderr);
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}
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if (remaining_param == NULL || !table_matching) {
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/* Exit if the layer type was not found, or if no '=' separator was found
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(see above) */
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g_free(decoded_param);
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return FALSE;
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}
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dissector_table_selector_type = get_dissector_table_selector_type(table_name);
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if (dissector_table_selector_type != FT_NONE) {
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if (*(remaining_param + 1) != '=') { /* Check for "==" and not only '=' */
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cmdarg_err("WARNING: -d requires \"==\" instead of \"=\". Option will be treated as \"%s==%s\"", table_name, remaining_param + 1);
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}
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else {
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remaining_param++; /* Move to the second '=' */
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*remaining_param = '\0'; /* Remove the second '=' */
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}
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remaining_param++; /* Position after the layer type string */
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/* This section extracts a selector value (selector_str) from decoded_param */
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selector_str = remaining_param; /* Next part starts with the selector number */
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remaining_param = strchr(selector_str, ',');
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if (remaining_param == NULL) {
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cmdarg_err("Parameter \"%s\" doesn't follow the template \"%s\"", cl_param, DECODE_AS_ARG_TEMPLATE);
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/* If the argument does not follow the template, carry on anyway to check
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if the selector value is at least correct. If remaining_param is NULL,
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we'll exit anyway further down */
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}
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else {
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*remaining_param = '\0'; /* Terminate the selector number string (selector_str) where ',' was detected */
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}
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}
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switch (dissector_table_selector_type) {
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case FT_UINT8:
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case FT_UINT16:
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case FT_UINT24:
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case FT_UINT32:
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{
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/* The selector for this table is an unsigned number. Parse it as such.
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Skip leading spaces for backwards compatibility (previously sscanf was used). */
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gchar *str = selector_str;
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gchar *end;
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guint64 val;
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while (g_ascii_isspace(*str)) {
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str++;
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}
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val = g_ascii_strtoull(str, &end, 0);
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if (str == end || val > G_MAXUINT32) {
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cmdarg_err("Invalid selector number \"%s\"", selector_str);
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g_free(decoded_param);
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return FALSE;
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}
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selector = (guint32) val;
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if (*end == '\0') {
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/* not a range, but a single (valid) value */
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op = '\0';
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selector2 = 0;
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} else if (*end == ':' || *end == '-') {
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/* range value such as "8888:3" or "8888-8890" */
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op = *end;
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str = end + 1;
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val = g_ascii_strtoull(str, &end, 0);
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if (str == end || val > G_MAXUINT32 || *end != '\0') {
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cmdarg_err("Invalid selector numeric range \"%s\"", selector_str);
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g_free(decoded_param);
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return FALSE;
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}
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selector2 = (guint32) val;
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if (op == ':') {
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if ((selector2 == 0) || ((guint64)selector + selector2 - 1) > G_MAXUINT32) {
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cmdarg_err("Invalid selector numeric range \"%s\"", selector_str);
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g_free(decoded_param);
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return FALSE;
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}
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}
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else if (selector2 < selector) {
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/* We could swap them for the user, but maybe it's better to call
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* this out as an error in case it's not what was intended? */
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cmdarg_err("Invalid selector numeric range \"%s\"", selector_str);
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g_free(decoded_param);
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return FALSE;
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}
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} else {
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/* neither a valid single value, nor a range. */
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cmdarg_err("Invalid selector number \"%s\"", selector_str);
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g_free(decoded_param);
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return FALSE;
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}
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break;
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}
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case FT_STRING:
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case FT_STRINGZ:
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case FT_UINT_STRING:
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case FT_STRINGZPAD:
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/* The selector for this table is a string. */
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break;
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case FT_NONE:
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/* There is no selector for this table */
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break;
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default:
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/* There are currently no dissector tables with any types other
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than the ones listed above. */
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g_assert_not_reached();
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}
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if (remaining_param == NULL) {
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/* Exit if no ',' separator was found (see above) */
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cmdarg_err("Valid protocols for layer type \"%s\" are:", table_name);
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fprint_all_protocols_for_layer_types(stderr, table_name);
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g_free(decoded_param);
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return FALSE;
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}
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remaining_param++; /* Position after the selector number string */
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/* This section extracts a protocol filter name (dissector_str) from decoded_param */
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dissector_str = remaining_param; /* All the rest of the string is the dissector (decode as protocol) name */
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/* Remove leading and trailing spaces from the dissector name */
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while (dissector_str[0] == ' ')
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dissector_str++;
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while (dissector_str[strlen(dissector_str) - 1] == ' ')
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dissector_str[strlen(dissector_str) - 1] = '\0'; /* Note: if empty string, while loop will eventually exit */
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dissector_matching = NULL;
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/* We now have a pointer to the handle for the requested table inside the variable table_matching */
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if (!(*dissector_str)) { /* Is the dissector name empty, if so, don't even search for a matching dissector and display all dissectors found for the selected table */
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cmdarg_err("No protocol name specified"); /* Note, we don't exit here, but dissector_matching will remain NULL, so we exit below */
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}
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else {
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header_field_info *hfi = proto_registrar_get_byalias(dissector_str);
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user_protocol_name.nb_match = 0;
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if (hfi) {
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user_protocol_name.searched_name = hfi->abbrev;
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} else {
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user_protocol_name.searched_name = dissector_str;
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}
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user_protocol_name.matched_handle = NULL;
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dissector_table_foreach_handle(table_name, find_protocol_name_func, &user_protocol_name); /* Go and perform the search for this dissector in the this table's dissectors' names and shortnames */
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if (user_protocol_name.nb_match != 0) {
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dissector_matching = user_protocol_name.matched_handle;
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if (user_protocol_name.nb_match > 1) {
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cmdarg_err("WARNING: Protocol \"%s\" matched %u dissectors, first one will be used", dissector_str, user_protocol_name.nb_match);
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}
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}
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else {
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/* OK, check whether the problem is that there isn't any such
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protocol, or that there is but it's not specified as a protocol
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that's valid for that dissector table.
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Note, we don't exit here, but dissector_matching will remain NULL,
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so we exit below */
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if (proto_get_id_by_filter_name(dissector_str) == -1) {
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/* No such protocol */
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cmdarg_err("Unknown protocol -- \"%s\"", dissector_str);
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}
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else {
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cmdarg_err("Protocol \"%s\" isn't valid for layer type \"%s\"",
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dissector_str, table_name);
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}
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}
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}
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if (!dissector_matching) {
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cmdarg_err("Valid protocols for layer type \"%s\" are:", table_name);
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fprint_all_protocols_for_layer_types(stderr, table_name);
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g_free(decoded_param);
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return FALSE;
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}
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/* This is the end of the code that parses the command-line options.
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All information is now stored in the variables:
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table_name
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selector
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dissector_matching
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The above variables that are strings are still pointing to areas within
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decoded_parm. decoded_parm thus still needs to be kept allocated in
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until we stop needing these variables
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decoded_param will be deallocated at each exit point of this function */
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/* We now have a pointer to the handle for the requested dissector
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(requested protocol) inside the variable dissector_matching */
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switch (dissector_table_selector_type) {
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case FT_UINT8:
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case FT_UINT16:
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case FT_UINT24:
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case FT_UINT32:
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/* The selector for this table is an unsigned number. */
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if (op == '\0') {
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dissector_change_uint(table_name, selector, dissector_matching);
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}
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else if (op == ':') {
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for (i = selector; i < (guint64)selector + selector2; i++) {
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dissector_change_uint(table_name, (guint32)i, dissector_matching);
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}
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}
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else { /* op == '-' */
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for (i = selector; i <= selector2; i++) {
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dissector_change_uint(table_name, (guint32)i, dissector_matching);
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}
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}
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break;
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case FT_STRING:
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case FT_STRINGZ:
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case FT_UINT_STRING:
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case FT_STRINGZPAD:
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/* The selector for this table is a string. */
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dissector_change_string(table_name, selector_str, dissector_matching);
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break;
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case FT_NONE:
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/* Just directly set the dissector found. */
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dissector_change_payload(table_name, dissector_matching);
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break;
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default:
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/* There are currently no dissector tables with any types other
|
|
than the ones listed above. */
|
|
g_assert_not_reached();
|
|
}
|
|
g_free(decoded_param); /* "Decode As" rule has been successfully added */
|
|
return TRUE;
|
|
}
|
|
|
|
/*
|
|
* Editor modelines
|
|
*
|
|
* Local Variables:
|
|
* c-basic-offset: 4
|
|
* tab-width: 8
|
|
* indent-tabs-mode: nil
|
|
* End:
|
|
*
|
|
* ex: set shiftwidth=4 tabstop=8 expandtab:
|
|
* :indentSize=4:tabSize=8:noTabs=true:
|
|
*/
|