Android7.1 关闭路由器DHCP后还能获取到ip地址

frameworks\base\services\net\java\android\net\dhcp\DhcpClient.java

 

确定 mIsIpRecoverEnabled=false;解决此问题。

原因：   

private boolean doIpRecover() {

        if (mIsIpRecoverEnabled == false) {

            Log.d(TAG, "IP recover: it was disabled");

            return false;

        }

        if (mPastDhcpLease == null) {

            Log.d(TAG, "IP recover: mPastDhcpLease is empty");

            return false;

        }

        Log.d(TAG, "IP recover: mPastDhcpLease = " + mPastDhcpLease);

 

        long reCaculatedLeaseMillis =

            mPastDhcpLease.systemExpiredTime - SystemClock.elapsedRealtime();

        Log.d(TAG, "IP recover: reCaculatedLeaseMillis = " + reCaculatedLeaseMillis);

 

        if (reCaculatedLeaseMillis < 0) {

            // configure infinite lease

            mDhcpLeaseExpiry = 0;

            Log.e(TAG, "IP recover: lease had been expired! configure to infinite lease");

        } else {

            mDhcpLeaseExpiry = SystemClock.elapsedRealtime() + reCaculatedLeaseMillis;

            Log.d(TAG, "IP recover: mDhcpLeaseExpiry = " + mDhcpLeaseExpiry);

        }

 

        byte arpResult[] = null;

        ArpPeer ap = null;

        boolean retVal = false;

        try {

            InetAddress ipAddress = mPastDhcpLease.ipAddress.getAddress();

            Log.d(TAG, "IP recover: arp address = " +

                "#$%K" +

                logDumpIpv4(3, ipAddress.getHostAddress()));

            ap = new ArpPeer(mIfaceName, Inet4Address.ANY, ipAddress);

            // doArp will blocking several seconds, to create thread if needed

            arpResult = ap.doArp(5000);

            if (arpResult == null) {

                int leaseDuration = (int)reCaculatedLeaseMillis/1000;

                mPastDhcpLease.setLeaseDuration(leaseDuration);

                acceptDhcpResults(mPastDhcpLease, "Confirmed");

                Log.d(TAG, "doIpRecover no arp response, IP can be reused");

                retVal = true;

            } else {

                Log.d(TAG, "doIpRecover DAD detected!!");

            }

        } catch (ErrnoException ee) {

            Log.d(TAG, "err :" + ee);

        } catch (IllegalArgumentException ie) {

            Log.d(TAG, "err :" + ie);

        } catch (SocketException se) {

            Log.d(TAG, "err :" + se);

        } finally {

            if (ap != null)    ap.close();

        }

        return retVal;

    }

    /// @}