/* * Copyright (C) 2015 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.server.connectivity; import static android.system.OsConstants.*; import android.net.LinkProperties; import android.net.Network; import android.net.NetworkUtils; import android.net.RouteInfo; import android.os.SystemClock; import android.system.ErrnoException; import android.system.Os; import android.system.StructTimeval; import android.text.TextUtils; import com.android.internal.util.IndentingPrintWriter; import java.io.Closeable; import java.io.FileDescriptor; import java.io.InterruptedIOException; import java.io.IOException; import java.net.Inet4Address; import java.net.Inet6Address; import java.net.InetAddress; import java.net.InetSocketAddress; import java.net.NetworkInterface; import java.net.SocketAddress; import java.net.SocketException; import java.net.UnknownHostException; import java.nio.ByteBuffer; import java.nio.charset.StandardCharsets; import java.util.concurrent.CountDownLatch; import java.util.concurrent.TimeUnit; import java.util.Arrays; import java.util.HashMap; import java.util.Map; import java.util.Random; import libcore.io.IoUtils; /** * NetworkDiagnostics * * A simple class to diagnose network connectivity fundamentals. Current * checks performed are: * - ICMPv4/v6 echo requests for all routers * - ICMPv4/v6 echo requests for all DNS servers * - DNS UDP queries to all DNS servers * * Currently unimplemented checks include: * - report ARP/ND data about on-link neighbors * - DNS TCP queries to all DNS servers * - HTTP DIRECT and PROXY checks * - port 443 blocking/TLS intercept checks * - QUIC reachability checks * - MTU checks * * The supplied timeout bounds the entire diagnostic process. Each specific * check class must implement this upper bound on measurements in whichever * manner is most appropriate and effective. * * @hide */ public class NetworkDiagnostics { private static final String TAG = "NetworkDiagnostics"; private static final InetAddress TEST_DNS4 = NetworkUtils.numericToInetAddress("8.8.8.8"); private static final InetAddress TEST_DNS6 = NetworkUtils.numericToInetAddress( "2001:4860:4860::8888"); // For brevity elsewhere. private static final long now() { return SystemClock.elapsedRealtime(); } // Values from RFC 1035 section 4.1.1, names from . // Should be a member of DnsUdpCheck, but "compiler says no". public static enum DnsResponseCode { NOERROR, FORMERR, SERVFAIL, NXDOMAIN, NOTIMP, REFUSED }; private final Network mNetwork; private final LinkProperties mLinkProperties; private final Integer mInterfaceIndex; private final long mTimeoutMs; private final long mStartTime; private final long mDeadlineTime; // A counter, initialized to the total number of measurements, // so callers can wait for completion. private final CountDownLatch mCountDownLatch; private class Measurement { private static final String SUCCEEDED = "SUCCEEDED"; private static final String FAILED = "FAILED"; // TODO: Refactor to make these private for better encapsulation. public String description = ""; public long startTime; public long finishTime; public String result = ""; public Thread thread; public void recordSuccess(String msg) { maybeFixupTimes(); result = SUCCEEDED + ": " + msg; if (mCountDownLatch != null) { mCountDownLatch.countDown(); } } public void recordFailure(String msg) { maybeFixupTimes(); result = FAILED + ": " + msg; if (mCountDownLatch != null) { mCountDownLatch.countDown(); } } private void maybeFixupTimes() { // Allows the caller to just set success/failure and not worry // about also setting the correct finishing time. if (finishTime == 0) { finishTime = now(); } // In cases where, for example, a failure has occurred before the // measurement even began, fixup the start time to reflect as much. if (startTime == 0) { startTime = finishTime; } } @Override public String toString() { return description + ": " + result + " (" + (finishTime - startTime) + "ms)"; } } private final Map mIcmpChecks = new HashMap<>(); private final Map mDnsUdpChecks = new HashMap<>(); private final String mDescription; public NetworkDiagnostics(Network network, LinkProperties lp, long timeoutMs) { mNetwork = network; mLinkProperties = lp; mInterfaceIndex = getInterfaceIndex(mLinkProperties.getInterfaceName()); mTimeoutMs = timeoutMs; mStartTime = now(); mDeadlineTime = mStartTime + mTimeoutMs; // Hardcode measurements to TEST_DNS4 and TEST_DNS6 in order to test off-link connectivity. // We are free to modify mLinkProperties with impunity because ConnectivityService passes us // a copy and not the original object. It's easier to do it this way because we don't need // to check whether the LinkProperties already contains these DNS servers because // LinkProperties#addDnsServer checks for duplicates. if (mLinkProperties.isReachable(TEST_DNS4)) { mLinkProperties.addDnsServer(TEST_DNS4); } // TODO: we could use mLinkProperties.isReachable(TEST_DNS6) here, because we won't set any // DNS servers for which isReachable() is false, but since this is diagnostic code, be extra // careful. if (mLinkProperties.hasGlobalIPv6Address() || mLinkProperties.hasIPv6DefaultRoute()) { mLinkProperties.addDnsServer(TEST_DNS6); } for (RouteInfo route : mLinkProperties.getRoutes()) { if (route.hasGateway()) { prepareIcmpMeasurement(route.getGateway()); } } for (InetAddress nameserver : mLinkProperties.getDnsServers()) { prepareIcmpMeasurement(nameserver); prepareDnsMeasurement(nameserver); } mCountDownLatch = new CountDownLatch(totalMeasurementCount()); startMeasurements(); mDescription = "ifaces{" + TextUtils.join(",", mLinkProperties.getAllInterfaceNames()) + "}" + " index{" + mInterfaceIndex + "}" + " network{" + mNetwork + "}" + " nethandle{" + mNetwork.getNetworkHandle() + "}"; } private static Integer getInterfaceIndex(String ifname) { try { NetworkInterface ni = NetworkInterface.getByName(ifname); return ni.getIndex(); } catch (NullPointerException | SocketException e) { return null; } } private void prepareIcmpMeasurement(InetAddress target) { if (!mIcmpChecks.containsKey(target)) { Measurement measurement = new Measurement(); measurement.thread = new Thread(new IcmpCheck(target, measurement)); mIcmpChecks.put(target, measurement); } } private void prepareDnsMeasurement(InetAddress target) { if (!mDnsUdpChecks.containsKey(target)) { Measurement measurement = new Measurement(); measurement.thread = new Thread(new DnsUdpCheck(target, measurement)); mDnsUdpChecks.put(target, measurement); } } private int totalMeasurementCount() { return mIcmpChecks.size() + mDnsUdpChecks.size(); } private void startMeasurements() { for (Measurement measurement : mIcmpChecks.values()) { measurement.thread.start(); } for (Measurement measurement : mDnsUdpChecks.values()) { measurement.thread.start(); } } public void waitForMeasurements() { try { mCountDownLatch.await(mDeadlineTime - now(), TimeUnit.MILLISECONDS); } catch (InterruptedException ignored) {} } public void dump(IndentingPrintWriter pw) { pw.println(TAG + ":" + mDescription); final long unfinished = mCountDownLatch.getCount(); if (unfinished > 0) { // This can't happen unless a caller forgets to call waitForMeasurements() // or a measurement isn't implemented to correctly honor the timeout. pw.println("WARNING: countdown wait incomplete: " + unfinished + " unfinished measurements"); } pw.increaseIndent(); for (Map.Entry entry : mIcmpChecks.entrySet()) { if (entry.getKey() instanceof Inet4Address) { pw.println(entry.getValue().toString()); } } for (Map.Entry entry : mIcmpChecks.entrySet()) { if (entry.getKey() instanceof Inet6Address) { pw.println(entry.getValue().toString()); } } for (Map.Entry entry : mDnsUdpChecks.entrySet()) { if (entry.getKey() instanceof Inet4Address) { pw.println(entry.getValue().toString()); } } for (Map.Entry entry : mDnsUdpChecks.entrySet()) { if (entry.getKey() instanceof Inet6Address) { pw.println(entry.getValue().toString()); } } pw.decreaseIndent(); } private class SimpleSocketCheck implements Closeable { protected final InetAddress mTarget; protected final int mAddressFamily; protected final Measurement mMeasurement; protected FileDescriptor mFileDescriptor; protected SocketAddress mSocketAddress; protected SimpleSocketCheck(InetAddress target, Measurement measurement) { mMeasurement = measurement; if (target instanceof Inet6Address) { Inet6Address targetWithScopeId = null; if (target.isLinkLocalAddress() && mInterfaceIndex != null) { try { targetWithScopeId = Inet6Address.getByAddress( null, target.getAddress(), mInterfaceIndex); } catch (UnknownHostException e) { mMeasurement.recordFailure(e.toString()); } } mTarget = (targetWithScopeId != null) ? targetWithScopeId : target; mAddressFamily = AF_INET6; } else { mTarget = target; mAddressFamily = AF_INET; } } protected void setupSocket( int sockType, int protocol, long writeTimeout, long readTimeout, int dstPort) throws ErrnoException, IOException { mFileDescriptor = Os.socket(mAddressFamily, sockType, protocol); // Setting SNDTIMEO is purely for defensive purposes. Os.setsockoptTimeval(mFileDescriptor, SOL_SOCKET, SO_SNDTIMEO, StructTimeval.fromMillis(writeTimeout)); Os.setsockoptTimeval(mFileDescriptor, SOL_SOCKET, SO_RCVTIMEO, StructTimeval.fromMillis(readTimeout)); // TODO: Use IP_RECVERR/IPV6_RECVERR, pending OsContants availability. mNetwork.bindSocket(mFileDescriptor); Os.connect(mFileDescriptor, mTarget, dstPort); mSocketAddress = Os.getsockname(mFileDescriptor); } protected String getSocketAddressString() { // The default toString() implementation is not the prettiest. InetSocketAddress inetSockAddr = (InetSocketAddress) mSocketAddress; InetAddress localAddr = inetSockAddr.getAddress(); return String.format( (localAddr instanceof Inet6Address ? "[%s]:%d" : "%s:%d"), localAddr.getHostAddress(), inetSockAddr.getPort()); } @Override public void close() { IoUtils.closeQuietly(mFileDescriptor); } } private class IcmpCheck extends SimpleSocketCheck implements Runnable { private static final int TIMEOUT_SEND = 100; private static final int TIMEOUT_RECV = 300; private static final int ICMPV4_ECHO_REQUEST = 8; private static final int ICMPV6_ECHO_REQUEST = 128; private static final int PACKET_BUFSIZE = 512; private final int mProtocol; private final int mIcmpType; public IcmpCheck(InetAddress target, Measurement measurement) { super(target, measurement); if (mAddressFamily == AF_INET6) { mProtocol = IPPROTO_ICMPV6; mIcmpType = ICMPV6_ECHO_REQUEST; mMeasurement.description = "ICMPv6"; } else { mProtocol = IPPROTO_ICMP; mIcmpType = ICMPV4_ECHO_REQUEST; mMeasurement.description = "ICMPv4"; } mMeasurement.description += " dst{" + mTarget.getHostAddress() + "}"; } @Override public void run() { // Check if this measurement has already failed during setup. if (mMeasurement.finishTime > 0) { // If the measurement failed during construction it didn't // decrement the countdown latch; do so here. mCountDownLatch.countDown(); return; } try { setupSocket(SOCK_DGRAM, mProtocol, TIMEOUT_SEND, TIMEOUT_RECV, 0); } catch (ErrnoException | IOException e) { mMeasurement.recordFailure(e.toString()); return; } mMeasurement.description += " src{" + getSocketAddressString() + "}"; // Build a trivial ICMP packet. final byte[] icmpPacket = { (byte) mIcmpType, 0, 0, 0, 0, 0, 0, 0 // ICMP header }; int count = 0; mMeasurement.startTime = now(); while (now() < mDeadlineTime - (TIMEOUT_SEND + TIMEOUT_RECV)) { count++; icmpPacket[icmpPacket.length - 1] = (byte) count; try { Os.write(mFileDescriptor, icmpPacket, 0, icmpPacket.length); } catch (ErrnoException | InterruptedIOException e) { mMeasurement.recordFailure(e.toString()); break; } try { ByteBuffer reply = ByteBuffer.allocate(PACKET_BUFSIZE); Os.read(mFileDescriptor, reply); // TODO: send a few pings back to back to guesstimate packet loss. mMeasurement.recordSuccess("1/" + count); break; } catch (ErrnoException | InterruptedIOException e) { continue; } } if (mMeasurement.finishTime == 0) { mMeasurement.recordFailure("0/" + count); } close(); } } private class DnsUdpCheck extends SimpleSocketCheck implements Runnable { private static final int TIMEOUT_SEND = 100; private static final int TIMEOUT_RECV = 500; private static final int DNS_SERVER_PORT = 53; private static final int RR_TYPE_A = 1; private static final int RR_TYPE_AAAA = 28; private static final int PACKET_BUFSIZE = 512; private final Random mRandom = new Random(); // Should be static, but the compiler mocks our puny, human attempts at reason. private String responseCodeStr(int rcode) { try { return DnsResponseCode.values()[rcode].toString(); } catch (IndexOutOfBoundsException e) { return String.valueOf(rcode); } } private final int mQueryType; public DnsUdpCheck(InetAddress target, Measurement measurement) { super(target, measurement); // TODO: Ideally, query the target for both types regardless of address family. if (mAddressFamily == AF_INET6) { mQueryType = RR_TYPE_AAAA; } else { mQueryType = RR_TYPE_A; } mMeasurement.description = "DNS UDP dst{" + mTarget.getHostAddress() + "}"; } @Override public void run() { // Check if this measurement has already failed during setup. if (mMeasurement.finishTime > 0) { // If the measurement failed during construction it didn't // decrement the countdown latch; do so here. mCountDownLatch.countDown(); return; } try { setupSocket(SOCK_DGRAM, IPPROTO_UDP, TIMEOUT_SEND, TIMEOUT_RECV, DNS_SERVER_PORT); } catch (ErrnoException | IOException e) { mMeasurement.recordFailure(e.toString()); return; } mMeasurement.description += " src{" + getSocketAddressString() + "}"; // This needs to be fixed length so it can be dropped into the pre-canned packet. final String sixRandomDigits = Integer.valueOf(mRandom.nextInt(900000) + 100000).toString(); mMeasurement.description += " qtype{" + mQueryType + "}" + " qname{" + sixRandomDigits + "-android-ds.metric.gstatic.com}"; // Build a trivial DNS packet. final byte[] dnsPacket = getDnsQueryPacket(sixRandomDigits); int count = 0; mMeasurement.startTime = now(); while (now() < mDeadlineTime - (TIMEOUT_RECV + TIMEOUT_RECV)) { count++; try { Os.write(mFileDescriptor, dnsPacket, 0, dnsPacket.length); } catch (ErrnoException | InterruptedIOException e) { mMeasurement.recordFailure(e.toString()); break; } try { ByteBuffer reply = ByteBuffer.allocate(PACKET_BUFSIZE); Os.read(mFileDescriptor, reply); // TODO: more correct and detailed evaluation of the response, // possibly adding the returned IP address(es) to the output. final String rcodeStr = (reply.limit() > 3) ? " " + responseCodeStr((int) (reply.get(3)) & 0x0f) : ""; mMeasurement.recordSuccess("1/" + count + rcodeStr); break; } catch (ErrnoException | InterruptedIOException e) { continue; } } if (mMeasurement.finishTime == 0) { mMeasurement.recordFailure("0/" + count); } close(); } private byte[] getDnsQueryPacket(String sixRandomDigits) { byte[] rnd = sixRandomDigits.getBytes(StandardCharsets.US_ASCII); return new byte[] { (byte) mRandom.nextInt(), (byte) mRandom.nextInt(), // [0-1] query ID 1, 0, // [2-3] flags; byte[2] = 1 for recursion desired (RD). 0, 1, // [4-5] QDCOUNT (number of queries) 0, 0, // [6-7] ANCOUNT (number of answers) 0, 0, // [8-9] NSCOUNT (number of name server records) 0, 0, // [10-11] ARCOUNT (number of additional records) 17, rnd[0], rnd[1], rnd[2], rnd[3], rnd[4], rnd[5], '-', 'a', 'n', 'd', 'r', 'o', 'i', 'd', '-', 'd', 's', 6, 'm', 'e', 't', 'r', 'i', 'c', 7, 'g', 's', 't', 'a', 't', 'i', 'c', 3, 'c', 'o', 'm', 0, // null terminator of FQDN (root TLD) 0, (byte) mQueryType, // QTYPE 0, 1 // QCLASS, set to 1 = IN (Internet) }; } } }