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Expressly forbid IP string literals as Private DNS hostnames

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For obvious bootstrapping reasons, DNS settings have always used
IP address string literals in input fields.

However, since we can use the network-assigned nameservers to bootstrap
our way to multiple IP addresses of multiple families (!), hostnames
provide a clear simplicity and future-proofing advantage.

Permitting IP address literals means not only making sure that we can
validate X.509v3 certificates for IP addresses, but coping with the
inevitable broken configurations where users may have configured IPv4
addresses but no IPv6 addresses.  This will unnecessarily complicate
life on IPv6-only networks.

=)

Test: as follows
    - built
    - flashed
    - booted
    - tried to enter IP string literals
    - make -j50 RunSettingsRoboTests ROBOTEST_FILTER=PrivateDnsModeDialogPreferenceTest
Bug: 34953048
Bug: 64133961
Bug: 73641539

Change-Id: I7a58e86ed640ff5600906fb3d8cb9a2c75598831
This commit is contained in:
Erik Kline
2018-04-02 21:52:55 -07:00
parent 54ee35c35c
commit 6c2ad0d62d
3 changed files with 95 additions and 13 deletions
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24
src/com/android/settings/network/PrivateDnsModeDialogPreference.java
View File

@@ -18,6 +18,8 @@ package com.android.settings.network;
import static android.net.ConnectivityManager.PRIVATE_DNS_MODE_OFF;
import static android.net.ConnectivityManager.PRIVATE_DNS_MODE_OPPORTUNISTIC;
import static android.net.ConnectivityManager.PRIVATE_DNS_MODE_PROVIDER_HOSTNAME;
import static android.system.OsConstants.AF_INET;
import static android.system.OsConstants.AF_INET6;
import android.app.AlertDialog;
import android.content.ActivityNotFoundException;
@@ -27,6 +29,7 @@ import android.content.DialogInterface;
import android.content.Intent;
import android.provider.Settings;
import android.support.annotation.VisibleForTesting;
import android.system.Os;
import android.text.Editable;
import android.text.TextWatcher;
import android.text.method.LinkMovementMethod;
@@ -45,6 +48,7 @@ import com.android.settings.utils.AnnotationSpan;
import com.android.settingslib.CustomDialogPreference;
import com.android.settingslib.HelpUtils;
import java.net.InetAddress;
import java.util.HashMap;
import java.util.Map;
@@ -67,6 +71,8 @@ public class PrivateDnsModeDialogPreference extends CustomDialogPreference imple
PRIVATE_DNS_MAP.put(PRIVATE_DNS_MODE_PROVIDER_HOSTNAME, R.id.private_dns_mode_provider);
}
private static final int[] ADDRESS_FAMILIES = new int[]{AF_INET, AF_INET6};
@VisibleForTesting
static final String MODE_KEY = Settings.Global.PRIVATE_DNS_MODE;
@VisibleForTesting
@@ -180,12 +186,20 @@ public class PrivateDnsModeDialogPreference extends CustomDialogPreference imple
}
private boolean isWeaklyValidatedHostname(String hostname) {
// TODO(b/34953048): Find and use a better validation method. Specifically:
// [1] this should reject IP string literals, and
// [2] do the best, simplest, future-proof verification that
// the input approximates a DNS hostname.
// TODO(b/34953048): Use a validation method that permits more accurate,
// but still inexpensive, checking of likely valid DNS hostnames.
final String WEAK_HOSTNAME_REGEX = "^[a-zA-Z0-9_.-]+$";
return hostname.matches(WEAK_HOSTNAME_REGEX);
if (!hostname.matches(WEAK_HOSTNAME_REGEX)) {
return false;
}
for (int address_family : ADDRESS_FAMILIES) {
if (Os.inet_pton(address_family, hostname) != null) {
return false;
}
}
return true;
}
private Button getSaveButton() {