DCERPC: simplify pointer list tracking
Observe that the "current_depth" and "len_ndr_pointer_list" just track the length of the current singly linked list in order to insert (append) or remove [the last] element (a linked list of lists and a linked list of pointers respectively). Replace these callers by equivalents that do not require explicit length tracking, internally they both have to do a O(n) lookup anyway. There used to be a case where "current_depth" could run out-of-sync, no longer tracking the actual list length: when the callback (tnpd->fnct or tnpd->callback) triggers an exception. I believe this was unintentional. No functional change intended, but this should make further changes to the data structures easier. Change-Id: I3cb13aba22caa87dc7baba411cf34f47792f7bb7 Ping-Bug: 14735 Fixes: v2.5.0rc0-292-g6bd87bdd5d ("dcerpc: improve greatly the speed of processing of DCERPC packets") Reviewed-on: https://code.wireshark.org/review/30114 Petri-Dish: Peter Wu <peter@lekensteyn.nl> Tested-by: Petri Dish Buildbot Reviewed-by: Anders Broman <a.broman58@gmail.com>
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@ -2875,9 +2875,6 @@ dissect_ndr_wchar_vstring(tvbuff_t *tvb, int offset, packet_info *pinfo,
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FALSE, NULL);
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}
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static int current_depth = 0;
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static int len_ndr_pointer_list = 0;
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/* ndr pointer handling */
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/* Should we re-read the size of the list ?
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* Instead of re-calculating the size everytime, use the stored value unless this
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@ -2929,7 +2926,6 @@ void
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init_ndr_pointer_list(dcerpc_info *di)
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{
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di->conformant_run = 0;
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current_depth = 0;
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while (list_ndr_pointer_list) {
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GSList *list = (GSList *)g_slist_nth_data(list_ndr_pointer_list, 0);
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@ -2943,13 +2939,12 @@ init_ndr_pointer_list(dcerpc_info *di)
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must_check_size = FALSE;
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ndr_pointer_list = create_empty_list();
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list_ndr_pointer_list = g_slist_insert(list_ndr_pointer_list,
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ndr_pointer_list, 0);
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list_ndr_pointer_list = g_slist_append(list_ndr_pointer_list,
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ndr_pointer_list);
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if (ndr_pointer_hash) {
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g_hash_table_destroy(ndr_pointer_hash);
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}
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ndr_pointer_hash = g_hash_table_new(g_int_hash, g_int_equal);
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len_ndr_pointer_list = 1;
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}
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int
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@ -2958,15 +2953,17 @@ dissect_deferred_pointers(packet_info *pinfo, tvbuff_t *tvb, int offset, dcerpc_
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int found_new_pointer;
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int old_offset;
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int next_pointer;
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int original_depth;
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unsigned original_depth;
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int len;
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GSList *current_ndr_pointer_list;
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ndr_pointer_list = NULL;
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next_pointer = 0;
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original_depth = current_depth;
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current_ndr_pointer_list = (GSList *)g_slist_nth_data(list_ndr_pointer_list, current_depth);
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/* Obtain the current list of pointers at this level. */
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current_ndr_pointer_list = (GSList *)g_slist_last(list_ndr_pointer_list)->data;
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original_depth = g_slist_length(list_ndr_pointer_list);
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len = g_slist_length(current_ndr_pointer_list);
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do {
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@ -2977,7 +2974,6 @@ dissect_deferred_pointers(packet_info *pinfo, tvbuff_t *tvb, int offset, dcerpc_
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ndr_pointer_data_t *tnpd = (ndr_pointer_data_t *)g_slist_nth_data(current_ndr_pointer_list, i);
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if (tnpd->fnct) {
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int saved_len_ndr_pointer_list = 0;
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GSList *saved_ndr_pointer_list = NULL;
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dcerpc_dissect_fnct_t *fnct;
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@ -2992,10 +2988,7 @@ dissect_deferred_pointers(packet_info *pinfo, tvbuff_t *tvb, int offset, dcerpc_
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di->conformant_run = 1;
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di->conformant_eaten = 0;
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old_offset = offset;
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current_depth++;
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saved_ndr_pointer_list = current_ndr_pointer_list;
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saved_len_ndr_pointer_list = len_ndr_pointer_list;
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len_ndr_pointer_list = 1;
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ndr_pointer_list = create_empty_list();
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offset = (*(fnct))(tvb, offset, pinfo, NULL, di, drep);
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@ -3052,22 +3045,21 @@ dissect_deferred_pointers(packet_info *pinfo, tvbuff_t *tvb, int offset, dcerpc_
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if (tnpd->callback)
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tnpd->callback(pinfo, tnpd->tree, tnpd->item, di, tvb, old_offset, offset, tnpd->callback_args);
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proto_item_set_len(tnpd->item, offset - old_offset);
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if (len_ndr_pointer_list > 1) {
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if (ndr_pointer_list->next) {
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/* We found some pointers to dissect let's create one more level */
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len = len_ndr_pointer_list;
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len = g_slist_length(ndr_pointer_list);
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current_ndr_pointer_list = ndr_pointer_list;
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/* So we will arrive right away at the second element of the list
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* but that's not too importnt because the first one is always empty
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*/
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i = next_pointer = 0;
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list_ndr_pointer_list = g_slist_insert(list_ndr_pointer_list,
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ndr_pointer_list, current_depth);
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/* Save the old pointer list before moving to the next. */
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list_ndr_pointer_list = g_slist_append(list_ndr_pointer_list,
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ndr_pointer_list);
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ndr_pointer_list = create_empty_list();
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continue;
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} else {
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current_depth--;
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current_ndr_pointer_list = saved_ndr_pointer_list;
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len_ndr_pointer_list = saved_len_ndr_pointer_list;
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}
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}
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if (i == (len - 1) && (must_check_size == TRUE)) {
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@ -3079,12 +3071,11 @@ dissect_deferred_pointers(packet_info *pinfo, tvbuff_t *tvb, int offset, dcerpc_
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/* We reached the end of one level, go to the level bellow if possible
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* reset list a level n
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*/
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if ((i >= (len - 1)) && (current_depth > original_depth)) {
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if ((i >= (len - 1)) && (g_slist_length(list_ndr_pointer_list) > original_depth)) {
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GSList *list;
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/* Remove existing list */
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g_slist_free_full(current_ndr_pointer_list, g_free);
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list = (GSList *)g_slist_nth_data(list_ndr_pointer_list, current_depth);
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current_depth--;
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list = (GSList *)g_slist_last(list_ndr_pointer_list)->data;
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list_ndr_pointer_list = g_slist_remove(list_ndr_pointer_list, list);
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/* Rewind on the lower level, in theory it's not too great because we
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@ -3092,18 +3083,18 @@ dissect_deferred_pointers(packet_info *pinfo, tvbuff_t *tvb, int offset, dcerpc_
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* In practice it shouldn't be that bad !
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*/
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next_pointer = 0;
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current_ndr_pointer_list = (GSList *)g_slist_nth_data(list_ndr_pointer_list, current_depth);
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/* Move to the next list of pointers. */
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current_ndr_pointer_list = (GSList *)g_slist_last(list_ndr_pointer_list)->data;
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len = g_slist_length(current_ndr_pointer_list);
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len_ndr_pointer_list = len;
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found_new_pointer = 1;
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}
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} while (found_new_pointer);
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DISSECTOR_ASSERT(original_depth == current_depth);
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DISSECTOR_ASSERT(original_depth == g_slist_length(list_ndr_pointer_list));
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g_slist_free_full(ndr_pointer_list, g_free);
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ndr_pointer_list = (GSList *)g_slist_nth_data(list_ndr_pointer_list, current_depth);
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len_ndr_pointer_list = g_slist_length(ndr_pointer_list);
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/* Restore the previous list of pointers. */
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ndr_pointer_list = (GSList *)g_slist_last(list_ndr_pointer_list)->data;
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return offset;
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}
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@ -3163,10 +3154,8 @@ add_pointer_to_list(packet_info *pinfo, proto_tree *tree, proto_item *item,
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p_id = wmem_new(wmem_file_scope(), guint);
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*p_id = id;
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ndr_pointer_list = g_slist_insert(ndr_pointer_list, npd,
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len_ndr_pointer_list);
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ndr_pointer_list = g_slist_append(ndr_pointer_list, npd);
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g_hash_table_insert(ndr_pointer_hash, p_id, p_id);
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len_ndr_pointer_list++;
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must_check_size = TRUE;
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}
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