WifiWatchdog changes for poor link detection

- use packet loss (wlutil pktcnt) instead of frame loss, retune all parameters
- use wpa_supplicant to get packet loss counters, instead of netd
- handle BSSID roaming in all situations
- improve flapping avoidance mechanism by setting different target RSSI
- handle high packet loss in high RSSI (never seen in real testing)
- add more comments on how to set all parameters

Signed-off-by yuhaozheng@google.com

Change-Id: I33429f063d8625a458be4791edd83a86d5a723df

wifi/java/android/net/wifi/WifiNative.java

@@ -368,6 +368,14 @@ public class WifiNative {
         return doStringCommand("SIGNAL_POLL");
     }
 
+    /** Example outout:
+     * TXGOOD=396
+     * TXBAD=1
+     */
+    public String pktcntPoll() {
+        return doStringCommand("PKTCNT_POLL");
+    }
+
     public boolean startWpsPbc(String bssid) {
         if (TextUtils.isEmpty(bssid)) {
             return doBooleanCommand("WPS_PBC");

wifi/java/android/net/wifi/WifiStateMachine.java

@@ -51,6 +51,7 @@ import android.net.LinkProperties;
 import android.net.NetworkInfo;
 import android.net.NetworkInfo.DetailedState;
 import android.net.NetworkUtils;
+import android.net.wifi.WifiWatchdogStateMachine.RssiPktcntStat;
 import android.net.wifi.WpsResult.Status;
 import android.net.wifi.p2p.WifiP2pManager;
 import android.net.wifi.p2p.WifiP2pService;
@@ -1163,7 +1164,7 @@ public class WifiStateMachine extends StateMachine {
             case CMD_RSSI_POLL:
             case CMD_DELAYED_STOP_DRIVER:
             case WifiMonitor.SCAN_RESULTS_EVENT:
-            case WifiWatchdogStateMachine.RSSI_FETCH:
+            case WifiWatchdogStateMachine.RSSI_PKTCNT_FETCH:
                 return false;
             default:
                 return true;
@@ -1514,6 +1515,30 @@ public class WifiStateMachine extends StateMachine {
         }
     }
 
+    /*
+     * Fetch TX packet counters on current connection
+     */
+    private void fetchPktcntNative(RssiPktcntStat stat) {
+        String pktcntPoll = mWifiNative.pktcntPoll();
+
+        if (pktcntPoll != null) {
+            String[] lines = pktcntPoll.split("\n");
+            for (String line : lines) {
+                String[] prop = line.split("=");
+                if (prop.length < 2) continue;
+                try {
+                    if (prop[0].equals("TXGOOD")) {
+                        stat.txgood = Integer.parseInt(prop[1]);
+                    } else if (prop[0].equals("TXBAD")) {
+                        stat.txbad = Integer.parseInt(prop[1]);
+                    }
+                } catch (NumberFormatException e) {
+                    //Ignore
+                }
+            }
+        }
+    }
+
     private void configureLinkProperties() {
         if (mWifiConfigStore.isUsingStaticIp(mLastNetworkId)) {
             mLinkProperties = mWifiConfigStore.getLinkProperties(mLastNetworkId);
@@ -1613,10 +1638,7 @@ public class WifiStateMachine extends StateMachine {
             mWifiInfo.setNetworkId(WifiConfiguration.INVALID_NETWORK_ID);
         }
 
-        if (state == SupplicantState.ASSOCIATING) {
-            /* BSSID is valid only in ASSOCIATING state */
-            mWifiInfo.setBSSID(stateChangeResult.BSSID);
-        }
+        mWifiInfo.setBSSID(stateChangeResult.BSSID);
         mWifiInfo.setSSID(stateChangeResult.SSID);
 
         mSupplicantStateTracker.sendMessage(Message.obtain(message));
@@ -1925,8 +1947,8 @@ public class WifiStateMachine extends StateMachine {
                     replyToMessage(message, WifiManager.DISABLE_NETWORK_FAILED,
                             WifiManager.BUSY);
                     break;
-                case WifiWatchdogStateMachine.RSSI_FETCH:
-                    replyToMessage(message, WifiWatchdogStateMachine.RSSI_FETCH_FAILED);
+                case WifiWatchdogStateMachine.RSSI_PKTCNT_FETCH:
+                    replyToMessage(message, WifiWatchdogStateMachine.RSSI_PKTCNT_FETCH_FAILED);
                     break;
                 default:
                     loge("Error! unhandled message" + message);
@@ -3129,10 +3151,13 @@ public class WifiStateMachine extends StateMachine {
                                 mRssiPollToken, 0), POLL_RSSI_INTERVAL_MSECS);
                     }
                     break;
-                case WifiWatchdogStateMachine.RSSI_FETCH:
+                case WifiWatchdogStateMachine.RSSI_PKTCNT_FETCH:
+                    RssiPktcntStat stat = (RssiPktcntStat) message.obj;
                     fetchRssiAndLinkSpeedNative();
-                    replyToMessage(message, WifiWatchdogStateMachine.RSSI_FETCH_SUCCEEDED,
-                            mWifiInfo.getRssi());
+                    stat.rssi = mWifiInfo.getRssi();
+                    fetchPktcntNative(stat);
+                    replyToMessage(message, WifiWatchdogStateMachine.RSSI_PKTCNT_FETCH_SUCCEEDED,
+                            stat);
                     break;
                 default:
                     return NOT_HANDLED;