// Copyright 2020 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
package org.chromium.chrome.browser.privacy.secure_dns;
import android.content.Context;
import android.text.Editable;
import android.text.Html;
import android.text.InputType;
import android.text.TextWatcher;
import android.text.method.LinkMovementMethod;
import android.util.AttributeSet;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.EditText;
import android.widget.RadioGroup;
import android.widget.Spinner;
import android.widget.TextView;
import androidx.annotation.NonNull;
import androidx.preference.Preference;
import androidx.preference.PreferenceViewHolder;
import com.google.android.material.textfield.TextInputLayout;
import org.chromium.chrome.browser.privacy.secure_dns.SecureDnsBridge.Entry;
import org.chromium.components.browser_ui.widget.RadioButtonWithDescription;
import org.chromium.components.browser_ui.widget.RadioButtonWithDescriptionLayout;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
/**
* SecureDnsProviderPreference is the user interface that is shown when Secure DNS is enabled.
* When Secure DNS is disabled, the SecureDnsProviderPreference is hidden.
*/
class SecureDnsProviderPreference extends Preference
implements RadioGroup.OnCheckedChangeListener,
AdapterView.OnItemSelectedListener,
TextWatcher {
// UI strings, loaded from the context.
private final String mPrivacyTemplate;
private final String mInvalidWarning;
private final String mProbeWarning;
// Server menu entries.
private final List<Entry> mOptions;
// UI elements. These fields are assigned only once, in onBindViewHolder.
private RadioButtonWithDescriptionLayout mGroup;
private RadioButtonWithDescription mAutomaticButton;
private RadioButtonWithDescription mSecureButton;
private Spinner mServerMenu;
private TextView mPrivacyPolicy;
private EditText mCustomServer;
private TextInputLayout mCustomServerLayout;
// All variable UI state for SecureDnsProviderPreference is encapsulated in this field.
// To ensure that the UI is updated whenever the state changes, this field
// should only be modified by setState().
private State mState;
// Checks whether the current template is actually reachable, and updates
// mCustomServerLayout's error state.
private final Runnable mProbeRunner = this::startServerProbe;
/**
* State is an immutable representation of the control's current UI state. It can represent
* states that are invalid, which are required when editing the template or changing modes.
*/
static class State {
// Indicates that secure mode is selected.
public final boolean secure;
// The selected or entered DoH template(s), if any.
public final @NonNull String config;
// Whether the selected template is valid.
public final boolean valid;
State(boolean secure, @NonNull String config, boolean valid) {
this.secure = secure;
this.config = config;
this.valid = valid;
}
@Override
public boolean equals(Object obj) {
if (obj instanceof State) {
State other = (State) obj;
return other.secure == secure
&& other.config.equals(config)
&& other.valid == valid;
}
return false;
}
@Override
public int hashCode() {
// This method is not used, but is defined here for consistency with equals().
return toString().hashCode();
}
State withSecure(boolean secure) {
return new State(secure, config, valid);
}
State withConfig(@NonNull String config) {
return new State(secure, config, valid);
}
State withValid(boolean valid) {
return new State(secure, config, valid);
}
@Override
public @NonNull String toString() {
return String.format("State(%b, %s, %b)", secure, config, valid);
}
}
public SecureDnsProviderPreference(Context context, AttributeSet attrs) {
super(context, attrs);
// Inflating from XML.
setLayoutResource(R.layout.secure_dns_provider_preference);
// Preload strings from disk.
mPrivacyTemplate = context.getString(R.string.settings_secure_dropdown_mode_privacy_policy);
mInvalidWarning = context.getString(R.string.settings_secure_dns_custom_format_error);
mProbeWarning = context.getString(R.string.settings_secure_dns_custom_connection_error);
mOptions = makeOptions(context);
}
private static List<Entry> makeOptions(Context context) {
List<Entry> entries = SecureDnsBridge.getProviders();
// The Spinner's options consist of an entry called "Custom", followed
// by the providers in random order.
List<Entry> options = new ArrayList<>(entries.size() + 1);
String customEntryName = context.getString(R.string.settings_custom);
options.add(new Entry(customEntryName, "", ""));
Collections.shuffle(entries);
options.addAll(entries);
return options;
}
@Override
public void onBindViewHolder(PreferenceViewHolder holder) {
super.onBindViewHolder(holder);
mGroup = (RadioButtonWithDescriptionLayout) holder.findViewById(R.id.mode_group);
mGroup.setOnCheckedChangeListener(this);
mAutomaticButton = (RadioButtonWithDescription) holder.findViewById(R.id.automatic);
mSecureButton = (RadioButtonWithDescription) holder.findViewById(R.id.secure);
View selectionContainer = holder.findViewById(R.id.selection_container);
mServerMenu = selectionContainer.findViewById(R.id.dropdown_spinner);
mServerMenu.setOnItemSelectedListener(this);
Context context = selectionContainer.getContext();
ArrayAdapter<Entry> adapter =
new ArrayAdapter<>(context, R.layout.secure_dns_provider_spinner_item, mOptions);
adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
mServerMenu.setAdapter(adapter);
mPrivacyPolicy = selectionContainer.findViewById(R.id.privacy_policy);
mPrivacyPolicy.setMovementMethod(LinkMovementMethod.getInstance());
mCustomServer = selectionContainer.findViewById(R.id.custom_server);
mCustomServer.addTextChangedListener(this);
// Show an action button instead of a carriage-return key.
mCustomServer.setRawInputType(InputType.TYPE_TEXT_VARIATION_URI);
mCustomServerLayout = selectionContainer.findViewById(R.id.custom_server_layout);
mGroup.attachAccessoryView(selectionContainer, mSecureButton);
updateView();
}
void setState(State state) {
if (!state.equals(mState)) {
mState = state;
updateView();
}
}
State getState() {
return mState;
}
// Returns the index of the dropdown entry that matches the current template,
// or 0 if none match (i.e. a custom template).
private int matchingDropdownIndex() {
for (int i = 1; i < mServerMenu.getCount(); ++i) {
Entry entry = (Entry) mServerMenu.getItemAtPosition(i);
if (entry.config.equals(mState.config)) {
return i;
}
}
return 0;
}
/** Updates the view to match mState. */
private void updateView() {
if (mGroup == null) {
// Not yet bound to view holder.
return;
}
if (mSecureButton.isChecked() != mState.secure) {
mSecureButton.setChecked(mState.secure);
}
boolean automaticMode = !mState.secure;
if (mAutomaticButton.isChecked() != automaticMode) {
mAutomaticButton.setChecked(automaticMode);
}
int position = matchingDropdownIndex();
if (mServerMenu.getSelectedItemPosition() != position) {
mServerMenu.setSelection(position);
}
if (mState.secure) {
mServerMenu.setVisibility(View.VISIBLE);
// Position 0 is the custom server. Other positions are actual server entries.
if (position > 0) {
// Selected server mode.
Entry entry = (Entry) mServerMenu.getSelectedItem();
String html = mPrivacyTemplate.replace("$1", entry.privacy);
mPrivacyPolicy.setText(Html.fromHtml(html));
mPrivacyPolicy.setVisibility(View.VISIBLE);
mCustomServerLayout.setVisibility(View.GONE);
} else {
// Custom server mode.
if (!mCustomServer.getText().toString().equals(mState.config)) {
mCustomServer.setText(mState.config);
mCustomServer.removeCallbacks(mProbeRunner);
if (mState.secure) {
mCustomServer.requestFocus();
// If the custom server field is idle for one second, run a probe.
// Any changes to the field will cancel this probe and start another.
mCustomServer.postDelayed(mProbeRunner, 1000);
}
}
// Show a warning if the input is invalid and is not the start of a valid URL.
boolean showWarning = !mState.valid && !"https://".startsWith(mState.config);
mCustomServerLayout.setError(showWarning ? mInvalidWarning : null);
mCustomServerLayout.setVisibility(View.VISIBLE);
mPrivacyPolicy.setVisibility(View.GONE);
}
} else {
mServerMenu.setVisibility(View.GONE);
mPrivacyPolicy.setVisibility(View.GONE);
mCustomServerLayout.setVisibility(View.GONE);
}
SecureDnsBridge.updateValidationHistogram(mState.valid);
}
private void startServerProbe() {
String group = mState.config;
if (group.isEmpty() || !mState.valid || !mState.secure) {
return;
}
// probeConfig() is a blocking network call that uses WaitableEvent, so it cannot run
// on the UI thread, nor via the Java PostTask bindings, which do not expose
// base::WithBaseSyncPrimitives. Instead, it runs on a fresh Java thread.
new Thread(
() -> {
if (SecureDnsBridge.probeConfig(group)) {
return;
}
mCustomServer.post(
() -> { // Send the state change back to the UI thread.
// Check that the setting hasn't been changed.
if (mState.config.contentEquals(group)) {
mCustomServerLayout.setError(mProbeWarning);
}
});
})
.start();
}
@Override
public void onCheckedChanged(RadioGroup group, int checkedId) {
boolean secure = checkedId == R.id.secure;
if (mState.secure != secure) {
tryUpdate(mState.withSecure(secure));
}
}
@Override
public void onItemSelected(AdapterView<?> parent, View view, int pos, long id) {
int oldPos = matchingDropdownIndex();
if (oldPos == pos) {
// This is the same item that was already in effect. Ignore spurious event.
// This check is required to avoid overwriting the custom template, because
// attaching an adapter triggers a spurious onItemSelected event.
return;
}
Entry entry = (Entry) parent.getItemAtPosition(pos);
tryUpdate(mState.withConfig(entry.config));
}
@Override
public void onNothingSelected(AdapterView<?> parent) {
// In this UI, one radio button is always selected.
}
private void tryUpdate(State newState) {
if (callChangeListener(newState)) {
setState(newState);
} else {
updateView();
}
}
@Override
public void beforeTextChanged(CharSequence s, int start, int count, int after) {}
@Override
public void onTextChanged(CharSequence s, int start, int count, int after) {}
@Override
public void afterTextChanged(Editable s) {
tryUpdate(mState.withConfig(s.toString()));
mCustomServer.removeCallbacks(mProbeRunner);
mCustomServer.postDelayed(mProbeRunner, 1000);
}
}
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