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// Copyright 2021 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "components/safe_browsing/content/browser/safe_browsing_navigation_observer_manager_util.h"
namespace safe_browsing {
void MaybeRemoveNonUserGestureReferrerEntries(ReferrerChain* referrer_chain,
int max_allowed_length) {
int extra_entries = referrer_chain->size() - max_allowed_length;
if (extra_entries > 0) {
RemoveNonUserGestureReferrerEntries(referrer_chain, max_allowed_length);
}
}
void RemoveNonUserGestureReferrerEntries(ReferrerChain* referrer_chain_entries,
int max_allowed_length) {
std::vector<int> user_gesture_indices =
GetUserGestureNavigationEntriesIndices(referrer_chain_entries);
// "Middle indices" means the entries adjacent to this entry are both non user
// gesture. "Non middle indices" means there is at least one adjacent entry
// that is non user gesture. The first and the last entries are non middle.
std::vector<int> middle_indices;
std::vector<int> non_middle_indices;
size_t entry_index = 0;
size_t user_gesture_index = 0;
for (ReferrerChainEntry& entry : *referrer_chain_entries) {
if (entry.navigation_initiation() !=
ReferrerChainEntry::RENDERER_INITIATED_WITHOUT_USER_GESTURE) {
entry_index++;
continue;
}
// If all the user gesture indices have been gone through, set the value to
// -2 because the user gesture index is checked +-1. This works because the
// index values in |user_gesture_indices| are in order from smallest to
// greatest.
size_t current_user_gesture_index_value =
(user_gesture_index < user_gesture_indices.size())
? user_gesture_indices.at(user_gesture_index)
: -2;
// An index is considered a middle index if it is not next to a user gesture
// index.
if ((current_user_gesture_index_value == entry_index) ||
(entry_index == (current_user_gesture_index_value + 1u)) ||
(entry_index == (current_user_gesture_index_value - 1u))) {
non_middle_indices.push_back(entry_index);
// If the current index is right after a user gesture index, move the user
// gesture index to the next index in the |user_gesture_indices|.
if (entry_index == (current_user_gesture_index_value + 1u)) {
user_gesture_index++;
}
} else {
middle_indices.push_back(entry_index);
}
entry_index++;
}
size_t extra_entries = referrer_chain_entries->size() - max_allowed_length;
int middle_omit_entries = middle_indices.size() < extra_entries
? middle_indices.size()
: extra_entries;
extra_entries = extra_entries - middle_omit_entries;
int non_middle_omit_entries = non_middle_indices.size() < extra_entries
? non_middle_indices.size()
: extra_entries;
RemoveExtraIndicesInReferrerChain(referrer_chain_entries, middle_indices,
middle_omit_entries);
RemoveExtraIndicesInReferrerChain(referrer_chain_entries, non_middle_indices,
non_middle_omit_entries);
}
std::vector<int> GetUserGestureNavigationEntriesIndices(
ReferrerChain* referrer_chain) {
std::vector<int> indices;
int index = 0;
for (ReferrerChainEntry& entry : *referrer_chain) {
if (entry.navigation_initiation() !=
ReferrerChainEntry::RENDERER_INITIATED_WITHOUT_USER_GESTURE) {
indices.push_back(index);
}
index++;
}
return indices;
}
void RemoveExtraIndicesInReferrerChain(ReferrerChain* referrer_chain_entries,
std::vector<int> indices_to_remove,
int extra_entries) {
if (extra_entries == 0) {
return;
}
size_t beginning_index = indices_to_remove.size() / 2 - extra_entries / 2;
if (beginning_index < 0) {
beginning_index = 0;
}
size_t end_index = beginning_index + (extra_entries - 1);
// There could be more |extra_entries| than the length of the
// |indices_to_remove|.
if (end_index > indices_to_remove.size()) {
end_index = indices_to_remove.size() - 1;
}
ReferrerChain entries_copy;
int removal_index;
int index = 0;
for (ReferrerChainEntry& entry : *referrer_chain_entries) {
if ((beginning_index <= end_index)) {
removal_index = indices_to_remove.at(beginning_index);
}
if (index == removal_index) {
// Replace with empty referrer_chain_entry.
std::unique_ptr<ReferrerChainEntry> referrer_chain_entry =
std::make_unique<ReferrerChainEntry>();
entries_copy.Add()->Swap(referrer_chain_entry.get());
beginning_index++;
} else {
entries_copy.Add()->Swap(&entry);
}
index++;
}
referrer_chain_entries->Swap(&entries_copy);
}
} // namespace safe_browsing
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