More work on firmware detection, recognition and validation #234

Should be as robust as possible now.

.gitignore

@@ -29,3 +29,5 @@ proguard/
 *.iml
 
 MPChartLib
+
+fw.dirs

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/miband/AbstractMi1FirmwareInfo.java

@@ -5,18 +5,37 @@ import android.support.annotation.NonNull;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+import nodomain.freeyourgadget.gadgetbridge.util.ArrayUtils;
+
 /**
  * Some helper methods for Mi1 and Mi1A firmware.
  */
 public abstract class AbstractMi1FirmwareInfo extends AbstractMiFirmwareInfo {
     private static final Logger LOG = LoggerFactory.getLogger(AbstractMi1FirmwareInfo.class);
 
+    private static final byte[] SINGLE_FW_HEADER = new byte[] {
+            0,
+            (byte)0x98,
+            0,
+            (byte)0x20,
+            (byte)0x89,
+            4,
+            0,
+            (byte)0x20
+    };
+    private static final int SINGLE_FW_HEADER_OFFSET = 0;
+
     private static final int MI1_FW_BASE_OFFSET = 1056;
 
     protected AbstractMi1FirmwareInfo(@NonNull byte[] wholeFirmwareBytes) {
         super(wholeFirmwareBytes);
     }
 
+    @Override
+    public boolean isSingleMiBandFirmware() {
+        return true;
+    }
+
     @Override
     public int getFirmwareOffset() {
         return 0;
@@ -51,11 +70,11 @@ public abstract class AbstractMi1FirmwareInfo extends AbstractMiFirmwareInfo {
 
     @Override
     protected boolean isGenerallySupportedFirmware() {
-        if (!isSingleMiBandFirmware()) {
-            LOG.warn("not a single firmware");
-            return false;
-        }
         try {
+            if (!isHeaderValid()) {
+                LOG.info("unrecognized header");
+                return false;
+            }
             int majorVersion = getFirmwareVersionMajor();
             if (majorVersion == getSupportedMajorVersion()) {
                 return true;
@@ -70,5 +89,19 @@ public abstract class AbstractMi1FirmwareInfo extends AbstractMiFirmwareInfo {
         return false;
     }
 
+    protected boolean isHeaderValid() {
+        // TODO: not sure if this is a correct check!
+        return ArrayUtils.equals(SINGLE_FW_HEADER, wholeFirmwareBytes, SINGLE_FW_HEADER_OFFSET, SINGLE_FW_HEADER_OFFSET + SINGLE_FW_HEADER.length);
+    }
+
+    @Override
+    public void checkValid() throws IllegalArgumentException {
+        super.checkValid();
+
+        if (wholeFirmwareBytes.length < SINGLE_FW_HEADER.length) {
+            throw new IllegalArgumentException("firmware too small: " + wholeFirmwareBytes.length);
+        }
+    }
+
     protected abstract int getSupportedMajorVersion();
 }

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/miband/AbstractMi1SFirmwareInfo.java

@@ -15,4 +15,9 @@ public abstract class AbstractMi1SFirmwareInfo extends AbstractMiFirmwareInfo {
     public boolean isGenerallyCompatibleWith(GBDevice device) {
         return MiBandConst.MI_1S.equals(device.getHardwareVersion());
     }
+
+    @Override
+    public boolean isSingleMiBandFirmware() {
+        return false;
+    }
 }

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/miband/AbstractMiFirmwareInfo.java

@@ -2,11 +2,14 @@ package nodomain.freeyourgadget.gadgetbridge.service.devices.miband;
 
 import android.support.annotation.NonNull;
 
+import java.lang.reflect.Array;
 import java.util.Arrays;
 
 import nodomain.freeyourgadget.gadgetbridge.impl.GBDevice;
+import nodomain.freeyourgadget.gadgetbridge.util.ArrayUtils;
 
 public abstract class AbstractMiFirmwareInfo {
+
     /**
      * @param wholeFirmwareBytes
      * @return
@@ -20,6 +23,7 @@ public abstract class AbstractMiFirmwareInfo {
             throw new IllegalArgumentException("Unsupported data (maybe not even a firmware?).");
         }
         if (candidates.length == 1) {
+            candidates[0].checkValid();
             return candidates[0];
         }
         throw new IllegalArgumentException("don't know for which device the firmware is, matches multiple devices");
@@ -58,6 +62,8 @@ public abstract class AbstractMiFirmwareInfo {
 
     protected abstract boolean isGenerallySupportedFirmware();
 
+    protected abstract boolean isHeaderValid();
+
     public abstract boolean isGenerallyCompatibleWith(GBDevice device);
 
     public @NonNull byte[] getFirmwareBytes() {
@@ -72,12 +78,9 @@ public abstract class AbstractMiFirmwareInfo {
         throw new IllegalArgumentException("bad firmware version: " + version);
     }
 
-    public boolean isSingleMiBandFirmware() {
+    public abstract boolean isSingleMiBandFirmware();
-        // TODO: not sure if this is a correct check!
+
-        if ((wholeFirmwareBytes[7] & 255) != 1) {
+    public void checkValid() throws IllegalArgumentException {
-            return true;
-        }
-        return false;
     }
 
     public AbstractMiFirmwareInfo getFirst() {

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/miband/Mi1SFirmwareInfo.java

@@ -5,6 +5,8 @@ import android.support.annotation.Nullable;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+import nodomain.freeyourgadget.gadgetbridge.util.ArrayUtils;
+
 /**
  * FW1 is Mi Band firmware
  * FW2 is heartrate firmware
@@ -12,6 +14,14 @@ import org.slf4j.LoggerFactory;
 public class Mi1SFirmwareInfo extends AbstractMi1SFirmwareInfo {
     private static final Logger LOG = LoggerFactory.getLogger(Mi1SFirmwareInfo.class);
 
+    private static final byte[] DOUBLE_FW_HEADER = new byte[] {
+            (byte)0x78,
+            (byte)0x75,
+            (byte)0x63,
+            (byte)0x6b
+    };
+    private static final int DOUBLE_FW_HEADER_OFFSET = 0;
+
     private final Mi1SFirmwareInfoFW1 fw1Info;
     private final Mi1SFirmwareInfoFW2 fw2Info;
 
@@ -21,6 +31,33 @@ public class Mi1SFirmwareInfo extends AbstractMi1SFirmwareInfo {
         fw2Info = new Mi1SFirmwareInfoFW2(wholeFirmwareBytes);
     }
 
+    protected boolean isHeaderValid() {
+        // TODO: not sure if this is a correct check!
+        return ArrayUtils.equals(DOUBLE_FW_HEADER, wholeFirmwareBytes, DOUBLE_FW_HEADER_OFFSET, DOUBLE_FW_HEADER_OFFSET + DOUBLE_FW_HEADER.length);
+    }
+
+    @Override
+    public void checkValid() throws IllegalArgumentException {
+        super.checkValid();
+        int firstEndIndex = getFirst().getFirmwareOffset() + getFirst().getFirmwareLength();
+        if (getSecond().getFirmwareOffset() < firstEndIndex) {
+            throw new IllegalArgumentException("Invalid firmware offsets/lengths: " + getLengthsOffsetsString());
+        }
+        int secondEndIndex = getSecond().getFirmwareOffset();
+        if (wholeFirmwareBytes.length < firstEndIndex || wholeFirmwareBytes.length < secondEndIndex) {
+            throw new IllegalArgumentException("Invalid firmware size, or invalid offsets/lengths: " + getLengthsOffsetsString());
+        }
+        if (getSecond().getFirmwareOffset() < firstEndIndex) {
+            throw new IllegalArgumentException("Invalid firmware, second fw starts before first fw ends: " + firstEndIndex + "," + getSecond().getFirmwareOffset());
+        }
+    }
+
+    protected String getLengthsOffsetsString() {
+        return getFirst().getFirmwareOffset() + "," + getFirst().getFirmwareLength()
+                + "; "
+                + getSecond().getFirmwareOffset() + "," + getSecond().getFirmwareLength();
+    }
+
     @Override
     public AbstractMiFirmwareInfo getFirst() {
         return fw1Info;
@@ -44,10 +81,11 @@ public class Mi1SFirmwareInfo extends AbstractMi1SFirmwareInfo {
 
     @Override
     protected boolean isGenerallySupportedFirmware() {
-        if (isSingleMiBandFirmware()) {
-            return false;
-        }
         try {
+            if (!isHeaderValid()) {
+                LOG.info("unrecognized header");
+                return false;
+            }
             return fw1Info.isGenerallySupportedFirmware()
                     && fw2Info.isGenerallySupportedFirmware()
                     && fw1Info.getFirmwareBytes().length > 0

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/miband/Mi1SFirmwareInfoFW1.java

@@ -17,6 +17,11 @@ public class Mi1SFirmwareInfoFW1 extends AbstractMi1SFirmwareInfo {
         super(wholeFirmwareBytes);
     }
 
+    @Override
+    protected boolean isHeaderValid() {
+        return true;
+    }
+
     @Override
     public int getFirmwareOffset() {
         return (wholeFirmwareBytes[12] & 255) << 24

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/miband/Mi1SFirmwareInfoFW2.java

@@ -16,6 +16,11 @@ public class Mi1SFirmwareInfoFW2 extends AbstractMi1SFirmwareInfo {
         super(wholeFirmwareBytes);
     }
 
+    @Override
+    protected boolean isHeaderValid() {
+        return true;
+    }
+
     @Override
     public int getFirmwareOffset() {
         return (wholeFirmwareBytes[26] & 255) << 24

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/util/ArrayUtils.java

@@ -0,0 +1,38 @@
+package nodomain.freeyourgadget.gadgetbridge.util;
+
+public class ArrayUtils {
+    /**
+     * Checks the two given arrays for equality, but comparing only a subset of the second
+     * array with the whole first array.
+     * @param first the whole array to compare against
+     * @param second the array, of which a subset shall be compared against the whole first array
+     * @param secondStartIndex the start index (inclusive) of the second array from which to start the comparison
+     * @param secondEndIndex the end index (exclusive) of the second array until which to compare
+     * @return whether the first byte array is equal to the specified subset of the second byte array
+     * @throws IllegalArgumentException when one of the arrays is null or start and end index are wrong
+     */
+    public static boolean equals(byte[] first, byte[] second, int secondStartIndex, int secondEndIndex) {
+        if (first == null) {
+            throw new IllegalArgumentException("first must not be null");
+        }
+        if (second == null) {
+            throw new IllegalArgumentException("second must not be null");
+        }
+        if (secondStartIndex >= secondEndIndex) {
+            throw new IllegalArgumentException("secondStartIndex must be smaller than secondEndIndex");
+        }
+        if (second.length < secondEndIndex) {
+            throw new IllegalArgumentException("secondStartIndex must be smaller than secondEndIndex");
+        }
+        if (first.length < secondEndIndex) {
+            return false;
+        }
+        int len = secondEndIndex - secondStartIndex;
+        for (int i = 0; i < len; i++) {
+            if (first[i] != second[secondStartIndex + i]) {
+                return false;
+            }
+        }
+        return true;
+    }
+}

app/src/test/java/nodomain/freeyourgadget/gadgetbridge/service/devices/miband/FirmwareTest.java

@@ -1,6 +1,7 @@
 package nodomain.freeyourgadget.gadgetbridge.service.devices.miband;
 
 import org.junit.Assert;
+import org.junit.BeforeClass;
 import org.junit.Ignore;
 import org.junit.Test;
 
@@ -12,7 +13,7 @@ import java.util.Arrays;
 import nodomain.freeyourgadget.gadgetbridge.devices.miband.MiBandFWHelper;
 import nodomain.freeyourgadget.gadgetbridge.util.FileUtils;
 
-@Ignore("Disabled for travis -- needs vm parameter -DMiFirmwareDir=/path/to/firmware/directory/")
+//@Ignore("Disabled for travis -- needs vm parameter -DMiFirmwareDir=/path/to/firmware/directory/")
 public class FirmwareTest {
 
     private static final long MAX_FILE_SIZE_BYTES = 1024 * 1024; // 1MB
@@ -24,6 +25,11 @@ public class FirmwareTest {
     private static final int SINGLE = 1;
     private static final int DOUBLE = 2;
 
+    @BeforeClass
+    public static void setupSuite() {
+        getFirmwareDir(); // throws if firmware directory not available
+    }
+
     @Test
     public void testFirmwareMi1() throws Exception {
         byte[] wholeFw = getFirmwareMi();
@@ -124,11 +130,11 @@ public class FirmwareTest {
         return info;
     }
 
-    private File getFirmwareDir() {
+    private static File getFirmwareDir() {
         String path = System.getProperty("MiFirmwareDir");
-        Assert.assertNotNull(path);
+        Assert.assertNotNull("You must run this test with -DMiFirmwareDir=/path/to/directory/with/miband/firmwarefiles/", path);
         File dir = new File(path);
-        Assert.assertTrue(dir.isDirectory());
+        Assert.assertTrue("System property MiFirmwareDir should point to a directory continaing the Mi Band firmware files", dir.isDirectory());
         return dir;
     }