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Commit 9ea70f6f authored by Kyeongkab.Nam's avatar Kyeongkab.Nam
Browse files

Change the logic of getting ntp server 

Changed to refer multiple addresses as a fail-safe and added to check
reference timestamp of ntp packet.

Bug: 139905217
Test: sync time by NTP after AC off/on.
Change-Id: I5ae5eca85ca679eded9d7878fb07a7b7617b2596
parent f2027253

core/java/android/net/SntpClient.java

+19 −9
Original line number Diff line number Diff line
@@ -25,6 +25,7 @@ import com.android.internal.util.TrafficStatsConstants; 
import java.net.DatagramPacket;

import java.net.DatagramSocket;

import java.net.InetAddress;

import java.net.UnknownHostException;

import java.util.Arrays;



/**
@@ -86,21 +87,26 @@ public class SntpClient { 
     * Sends an SNTP request to the given host and processes the response.

     *

     * @param host host name of the server.

     * @param timeout network timeout in milliseconds.

     * @param timeout network timeout in milliseconds. the timeout doesn't include the DNS lookup

     *                time, and it applies to each individual query to the resolved addresses of

     *                the NTP server.

     * @param network network over which to send the request.

     * @return true if the transaction was successful.

     */

    public boolean requestTime(String host, int timeout, Network network) {

        final Network networkForResolv = network.getPrivateDnsBypassingCopy();

        InetAddress address = null;

        try {

            address = networkForResolv.getByName(host);

        } catch (Exception e) {

            final InetAddress[] addresses = networkForResolv.getAllByName(host);

            for (int i = 0; i < addresses.length; i++) {

                if (requestTime(addresses[i], NTP_PORT, timeout, networkForResolv)) return true;

            }

        } catch (UnknownHostException e) {

            Log.w(TAG, "Unknown host: " + host);

            EventLogTags.writeNtpFailure(host, e.toString());

            if (DBG) Log.d(TAG, "request time failed: " + e);

            return false;

        }

        return requestTime(address, NTP_PORT, timeout, networkForResolv);



        if (DBG) Log.d(TAG, "request time failed");

        return false;

    }



    public boolean requestTime(InetAddress address, int port, int timeout, Network network) {
@@ -139,10 +145,11 @@ public class SntpClient { 
            final long originateTime = readTimeStamp(buffer, ORIGINATE_TIME_OFFSET);

            final long receiveTime = readTimeStamp(buffer, RECEIVE_TIME_OFFSET);

            final long transmitTime = readTimeStamp(buffer, TRANSMIT_TIME_OFFSET);

            final long referenceTime = readTimeStamp(buffer, REFERENCE_TIME_OFFSET);



            /* do sanity check according to RFC */

            // TODO: validate originateTime == requestTime.

            checkValidServerReply(leap, mode, stratum, transmitTime);

            checkValidServerReply(leap, mode, stratum, transmitTime, referenceTime);



            long roundTripTime = responseTicks - requestTicks - (transmitTime - receiveTime);

            // receiveTime = originateTime + transit + skew
@@ -218,7 +225,7 @@ public class SntpClient { 
    }



    private static void checkValidServerReply(

            byte leap, byte mode, int stratum, long transmitTime)

            byte leap, byte mode, int stratum, long transmitTime, long referenceTime)

            throws InvalidServerReplyException {

        if (leap == NTP_LEAP_NOSYNC) {

            throw new InvalidServerReplyException("unsynchronized server");
@@ -232,6 +239,9 @@ public class SntpClient { 
        if (transmitTime == 0) {

            throw new InvalidServerReplyException("zero transmitTime");

        }

        if (referenceTime == 0) {

            throw new InvalidServerReplyException("zero reference timestamp");

        }

    }



    /**