| /* |
| * Copyright (C) 2019 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package com.android.networkstack.util; |
| |
| import static android.net.DnsResolver.FLAG_NO_CACHE_LOOKUP; |
| import static android.net.DnsResolver.TYPE_A; |
| import static android.net.DnsResolver.TYPE_AAAA; |
| |
| import android.net.DnsResolver; |
| import android.net.Network; |
| import android.net.TrafficStats; |
| import android.net.util.Stopwatch; |
| import android.util.Log; |
| |
| import androidx.annotation.NonNull; |
| import androidx.annotation.Nullable; |
| |
| import com.android.internal.util.TrafficStatsConstants; |
| import com.android.server.connectivity.NetworkMonitor.DnsLogFunc; |
| |
| import java.net.InetAddress; |
| import java.net.UnknownHostException; |
| import java.util.ArrayList; |
| import java.util.Arrays; |
| import java.util.List; |
| import java.util.concurrent.CompletableFuture; |
| import java.util.concurrent.ExecutionException; |
| import java.util.concurrent.TimeUnit; |
| import java.util.concurrent.TimeoutException; |
| |
| /** |
| * Collection of utilities for dns query. |
| */ |
| public class DnsUtils { |
| // Decide what queries to make depending on what IP addresses are on the system. |
| public static final int TYPE_ADDRCONFIG = -1; |
| // A one time host name suffix of private dns probe. |
| // q.v. system/netd/server/dns/DnsTlsTransport.cpp |
| public static final String PRIVATE_DNS_PROBE_HOST_SUFFIX = "-dnsotls-ds.metric.gstatic.com"; |
| private static final String TAG = DnsUtils.class.getSimpleName(); |
| private static final boolean DBG = Log.isLoggable(TAG, Log.DEBUG); |
| |
| /** |
| * Return both A and AAAA query results regardless the ip address type of the giving network. |
| * Used for probing in NetworkMonitor. |
| */ |
| @NonNull |
| public static InetAddress[] getAllByName(@NonNull final DnsResolver dnsResolver, |
| @NonNull final Network network, @NonNull String host, int timeout, |
| @NonNull final DnsLogFunc logger) throws UnknownHostException { |
| final List<InetAddress> result = new ArrayList<InetAddress>(); |
| final StringBuilder errorMsg = new StringBuilder(host); |
| |
| try { |
| result.addAll(Arrays.asList( |
| getAllByName(dnsResolver, network, host, TYPE_AAAA, FLAG_NO_CACHE_LOOKUP, |
| timeout, logger))); |
| } catch (UnknownHostException e) { |
| // Might happen if the host is v4-only, still need to query TYPE_A |
| errorMsg.append(String.format(" (%s)%s", dnsTypeToStr(TYPE_AAAA), e.getMessage())); |
| } |
| try { |
| result.addAll(Arrays.asList( |
| getAllByName(dnsResolver, network, host, TYPE_A, FLAG_NO_CACHE_LOOKUP, |
| timeout, logger))); |
| } catch (UnknownHostException e) { |
| // Might happen if the host is v6-only, still need to return AAAA answers |
| errorMsg.append(String.format(" (%s)%s", dnsTypeToStr(TYPE_A), e.getMessage())); |
| } |
| |
| if (result.size() == 0) { |
| logger.log("FAIL: " + errorMsg.toString()); |
| throw new UnknownHostException(host); |
| } |
| logger.log("OK: " + host + " " + result.toString()); |
| return result.toArray(new InetAddress[0]); |
| } |
| |
| /** |
| * Return dns query result based on the given QueryType(TYPE_A, TYPE_AAAA) or TYPE_ADDRCONFIG. |
| * Used for probing in NetworkMonitor. |
| */ |
| @NonNull |
| public static InetAddress[] getAllByName(@NonNull final DnsResolver dnsResolver, |
| @NonNull final Network network, @NonNull final String host, int type, int flag, |
| int timeoutMs, @Nullable final DnsLogFunc logger) throws UnknownHostException { |
| final CompletableFuture<List<InetAddress>> resultRef = new CompletableFuture<>(); |
| final Stopwatch watch = new Stopwatch().start(); |
| |
| |
| final DnsResolver.Callback<List<InetAddress>> callback = |
| new DnsResolver.Callback<List<InetAddress>>() { |
| @Override |
| public void onAnswer(List<InetAddress> answer, int rcode) { |
| if (rcode == 0 && answer != null && answer.size() != 0) { |
| resultRef.complete(answer); |
| } else { |
| resultRef.completeExceptionally(new UnknownHostException()); |
| } |
| } |
| |
| @Override |
| public void onError(@NonNull DnsResolver.DnsException e) { |
| if (DBG) { |
| Log.d(TAG, "DNS error resolving " + host, e); |
| } |
| resultRef.completeExceptionally(e); |
| } |
| }; |
| // TODO: Investigate whether this is still useful. |
| // The packets that actually do the DNS queries are sent by netd, but netd doesn't |
| // look at the tag at all. Given that this is a library, the tag should be passed in by the |
| // caller. |
| final int oldTag = TrafficStats.getAndSetThreadStatsTag( |
| TrafficStatsConstants.TAG_SYSTEM_PROBE); |
| |
| if (type == TYPE_ADDRCONFIG) { |
| dnsResolver.query(network, host, flag, r -> r.run(), null /* cancellationSignal */, |
| callback); |
| } else { |
| dnsResolver.query(network, host, type, flag, r -> r.run(), |
| null /* cancellationSignal */, callback); |
| } |
| |
| TrafficStats.setThreadStatsTag(oldTag); |
| |
| String errorMsg = null; |
| List<InetAddress> result = null; |
| try { |
| result = resultRef.get(timeoutMs, TimeUnit.MILLISECONDS); |
| } catch (ExecutionException e) { |
| errorMsg = e.getMessage(); |
| } catch (TimeoutException | InterruptedException e) { |
| errorMsg = "Timeout"; |
| } finally { |
| logDnsResult(result, watch.stop() / 1000 /* latencyMs */, logger, type, errorMsg); |
| } |
| |
| if (null != errorMsg) throw new UnknownHostException(host); |
| |
| return result.toArray(new InetAddress[0]); |
| } |
| |
| private static void logDnsResult(@Nullable final List<InetAddress> results, |
| final long latencyMs, @Nullable final DnsLogFunc logger, int type, |
| @NonNull final String errorMsg) { |
| if (logger == null) { |
| return; |
| } |
| |
| if (results != null && results.size() != 0) { |
| final StringBuilder builder = new StringBuilder(); |
| for (InetAddress address : results) { |
| builder.append(',').append(address.getHostAddress()); |
| } |
| logger.log(String.format("%dms OK %s", latencyMs, builder.substring(1))); |
| } else { |
| logger.log(String.format("%dms FAIL in type %s %s", latencyMs, dnsTypeToStr(type), |
| errorMsg)); |
| } |
| } |
| |
| private static String dnsTypeToStr(int type) { |
| switch (type) { |
| case TYPE_A: |
| return "A"; |
| case TYPE_AAAA: |
| return "AAAA"; |
| case TYPE_ADDRCONFIG: |
| return "ADDRCONFIG"; |
| default: |
| } |
| return "UNDEFINED"; |
| } |
| } |