Add wifi ScoringParams expid

Add an experiment identifier to wifi ScoringParams.

Also add a method to return a digest of the parameter values, which may
be useful for checking the accuracy of the expid label.

Bug: 79482323
Test: Unit tests added

Change-Id: Ic34c471b978576b734443fb93590809f45ae4c24

2 files changed, 73 insertions, 5 deletions

diff --git a/service/java/com/android/server/wifi/ScoringParams.java b/service/java/com/android/server/wifi/ScoringParams.java
index 5b9951ff8..6c42faf6b 100644
--- a/service/java/com/android/server/wifi/ScoringParams.java
+++ b/service/java/com/android/server/wifi/ScoringParams.java
@@ -27,6 +27,11 @@ import android.util.Log;
 
 import com.android.internal.R;
 
+import libcore.util.HexEncoding;
+
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+
 /**
  * Holds parameters used for scoring networks.
  *
@@ -70,6 +75,12 @@ public class ScoringParams {
         public static final int MAX_NUD = 10;
         public int nud = 8;
 
+        /** Experiment identifier */
+        public static final String KEY_EXPID = "expid";
+        public static final int MIN_EXPID = 0;
+        public static final int MAX_EXPID = Integer.MAX_VALUE;
+        public int expid = 0;
+
         Values() {
         }
 
@@ -85,6 +96,7 @@ public class ScoringParams {
             }
             horizon = source.horizon;
             nud = source.nud;
+            expid = source.expid;
         }
 
         public void validate() throws IllegalArgumentException {
@@ -93,6 +105,7 @@ public class ScoringParams {
             validateOrderedNonNegativeArray(pps);
             validateRange(horizon, MIN_HORIZON, MAX_HORIZON);
             validateRange(nud, MIN_NUD, MAX_NUD);
+            validateRange(expid, MIN_EXPID, MAX_EXPID);
         }
 
         private void validateRssiArray(int[] rssi) throws IllegalArgumentException {
@@ -131,6 +144,7 @@ public class ScoringParams {
             updateIntArray(pps, parser, KEY_PPS);
             horizon = updateInt(parser, KEY_HORIZON, horizon);
             nud = updateInt(parser, KEY_NUD, nud);
+            expid = updateInt(parser, KEY_EXPID, expid);
         }
 
         private int updateInt(KeyValueListParser parser, String key, int defaultValue)
@@ -168,6 +182,8 @@ public class ScoringParams {
             sb.append(horizon);
             appendKey(sb, KEY_NUD);
             sb.append(nud);
+            appendKey(sb, KEY_EXPID);
+            sb.append(expid);
             return sb.toString();
         }
 
@@ -352,6 +368,15 @@ public class ScoringParams {
         return mVal.nud;
     }
 
+    /**
+     * Returns the experiment identifier.
+     *
+     * This value may be used to tag a set of experimental settings.
+     */
+    public int getExperimentIdentifier() {
+        return mVal.expid;
+    }
+
     private static final int MINIMUM_5GHZ_BAND_FREQUENCY_IN_MEGAHERTZ = 5000;
 
     private int[] getRssiArray(int frequency) {
@@ -366,4 +391,17 @@ public class ScoringParams {
     public String toString() {
         return mVal.toString();
     }
+
+    /**
+     * Calculates the SHA-256 digest of the scoring params, encoded in hex.
+     */
+    public String hexDigest() {
+        String digest = null;
+        try {
+            MessageDigest messageDigest = MessageDigest.getInstance("SHA-256");
+            messageDigest.update(mVal.toString().getBytes());
+            digest = HexEncoding.encodeToString(messageDigest.digest());
+        } catch (NoSuchAlgorithmException e) { }
+        return digest;
+    }
 }
diff --git a/tests/wifitests/src/com/android/server/wifi/ScoringParamsTest.java b/tests/wifitests/src/com/android/server/wifi/ScoringParamsTest.java
index fc9b33ad2..fb7f868a7 100644
--- a/tests/wifitests/src/com/android/server/wifi/ScoringParamsTest.java
+++ b/tests/wifitests/src/com/android/server/wifi/ScoringParamsTest.java
@@ -49,7 +49,10 @@ import org.mockito.Spy;
 @SmallTest
 public class ScoringParamsTest {
 
-    ScoringParams mScoringParams;
+    private static final String EXPECTED_DEFAULTS =
+            "rssi2=-83:-80:-73:-60,rssi5=-80:-77:-70:-57,pps=0:1:100,horizon=15,nud=8,expid=0";
+
+    private ScoringParams mScoringParams;
 
     /**
      * Sets up for unit test
@@ -93,20 +96,30 @@ public class ScoringParamsTest {
     @Test
     public void testToString() throws Exception {
         mScoringParams = new ScoringParams();
-        String expect =
-                "rssi2=-83:-80:-73:-60,rssi5=-80:-77:-70:-57,pps=0:1:100,horizon=15,nud=8";
+        String expect = EXPECTED_DEFAULTS;
         String actual = mScoringParams.toString();
         assertEquals(expect, actual);
     }
 
     /**
+     * Test hexDigest
+     */
+    @Test
+    public void testHexDigest() throws Exception {
+        mScoringParams = new ScoringParams();
+        //hint: printf %s "$EXPECTED_DEFAULTS" | openssl dgst -hex -sha256
+        String expect = "BC3DB98DD8DD16C251FE9A0592444106B8FB09026D66558242196C7E81D1FAC2";
+        String actual = mScoringParams.hexDigest();
+        assertEquals(expect, actual);
+    }
+
+    /**
      * Test complete update
      */
     @Test
     public void testUpdateEverything() throws Exception {
         mScoringParams = new ScoringParams();
-        String params =
-                "rssi2=-86:-84:-77:-10,rssi5=-88:-77:-66:-55,pps=1:10:30,horizon=3,nud=3";
+        String params = EXPECTED_DEFAULTS.replaceAll("8", "9");
         assertTrue(mScoringParams.update(params));
         assertEquals(params, mScoringParams.toString());
     }
@@ -200,6 +213,22 @@ public class ScoringParamsTest {
     }
 
     /**
+     * Test that expid is hooked up, including effect on digest
+     */
+    @Test
+    public void testExperimentIdentifier() throws Exception {
+        mScoringParams = new ScoringParams();
+        String digestBefore = mScoringParams.hexDigest();
+        assertEquals(0, mScoringParams.getExperimentIdentifier());
+        assertTrue(mScoringParams.update("expid=99"));
+        assertEquals(99, mScoringParams.getExperimentIdentifier());
+        String digestAfter = mScoringParams.hexDigest();
+        assertTrue(!digestBefore.equals(digestAfter));
+        assertTrue(mScoringParams.update("expid=0"));
+        assertEquals(digestBefore, mScoringParams.hexDigest());
+    }
+
+    /**
      * Check character set
      */
     @Test
@@ -225,6 +254,7 @@ public class ScoringParamsTest {
         assertEquals(param100.substring(0, 90),
                 mScoringParams.sanitize(param100 + "00000000000").substring(0, 90));
         assertEquals("q?=???", mScoringParams.sanitize("q\b= ~["));
+        assertEquals("", mScoringParams.sanitize(null));
     }
 
     /**