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Code Issues 1 Packages Projects Releases Wiki Activity

Zepp OS: Parse activity details using ASN.1 BER

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This commit is contained in:
José Rebelo
2025-09-21 20:29:04 +01:00
parent 463543bac2
commit 7234f9c69f
1 changed files with 57 additions and 28 deletions
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app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/huami/zeppos/ZeppOsActivityDetailsParser.java
+57 -28
View File
@@ -70,25 +70,21 @@ public class ZeppOsActivityDetailsParser extends AbstractHuamiActivityDetailsPar
this.activityTrack.setName(createActivityName(summary));
}
/**
* Sequence of TLVs, encoded in
* <a href="https://www.oss.com/asn1/resources/asn1-made-simple/asn1-quick-reference/basic-encoding-rules.html">ASN.1 BER</a>
*/
@Override
public ZeppOsActivityTrack parse(final byte[] bytes) throws GBException {
final ByteBuffer buf = ByteBuffer.wrap(bytes)
.order(ByteOrder.LITTLE_ENDIAN);
// Keep track of unknown type codes so we can print them without spamming the logs
final Map<Byte, Integer> unknownTypeCodes = new HashMap<>();
final Map<Integer, Integer> unknownTypeCodes = new HashMap<>();
while (buf.position() < buf.limit()) {
byte typeCode = buf.get();
// FIXME: This is probably not right, but type 31 makes the parser get out of sync otherwise
if (typeCode == 31) {
typeCode = buf.get();
}
byte lengthByte = buf.get();
if (lengthByte == -127) {
lengthByte = buf.get();
}
final int length = lengthByte & 0xff;
final int typeCode = consumeTag(buf);
final int length = consumeLength(buf);
final int initialPosition = buf.position();
final Type type = Type.fromCode(typeCode);
@@ -156,7 +152,7 @@ public class ZeppOsActivityDetailsParser extends AbstractHuamiActivityDetailsPar
}
if (!unknownTypeCodes.isEmpty()) {
for (final Map.Entry<Byte, Integer> e : unknownTypeCodes.entrySet()) {
for (final Map.Entry<Integer, Integer> e : unknownTypeCodes.entrySet()) {
LOG.warn("Unknown type code {} seen {} times", String.format("0x%X", e.getKey()), e.getValue());
}
}
@@ -164,20 +160,53 @@ public class ZeppOsActivityDetailsParser extends AbstractHuamiActivityDetailsPar
return this.activityTrack;
}
private boolean isValidLength(final Type type, final int length) {
switch (type) {
case GPS_COORDS:
// Support both old format (20 bytes) and new Balance 2 format (28 bytes)
return length == 20 || length == 28;
case GPS_DELTA:
// Support both old format (8 bytes) and new Balance 2 format (16 bytes)
return length == 8 || length == 16;
case ALTITUDE:
// Support both old format (6 bytes) and new Balance 2 format (7 bytes)
return length == 6 || length == 7;
default:
return length == type.getExpectedLength();
private static int consumeTag(final ByteBuffer buf) {
final int first = buf.get() & 0xFF;
if ((first & 0x1F) != 0x1F) {
// single-byte tag
return first;
}
// multi-byte tag
int tag = first;
while (buf.hasRemaining()) {
int b = buf.get() & 0xFF;
tag = (tag << 8) | b;
if ((b & 0x80) == 0) break; // continuation bit cleared
}
return tag;
}
private static int consumeLength(final ByteBuffer buf) {
final int first = buf.get() & 0xFF;
if ((first & 0x80) == 0) {
// short form
return first;
}
// long form
final int numBytes = first & 0x7F;
if (numBytes == 0 || numBytes > 4) {
throw new IllegalStateException("Unsupported length encoding: " + numBytes);
}
int value = 0;
for (int i = 0; i < numBytes; i++) {
value = (value << 8) | (buf.get() & 0xFF);
}
return value;
}
private boolean isValidLength(final Type type, final int length) {
return switch (type) {
// Support both old format (20 bytes) and new Balance 2 format (28 bytes)
case GPS_COORDS -> length == 20 || length == 28;
// Support both old format (8 bytes) and new Balance 2 format (16 bytes)
case GPS_DELTA -> length == 8 || length == 16;
// Support both old format (6 bytes) and new Balance 2 format (7 bytes)
case ALTITUDE -> length == 6 || length == 7;
default -> length == type.getExpectedLength();
};
}
private void consumeTimestamp(final ByteBuffer buf) {
@@ -196,7 +225,7 @@ public class ZeppOsActivityDetailsParser extends AbstractHuamiActivityDetailsPar
buf.get(new byte[6]); // ?
this.longitude = buf.getInt();
this.latitude = buf.getInt();
// Handle different formats
if (length == 20) {
// Old format: skip remaining 6 bytes
@@ -291,7 +320,7 @@ public class ZeppOsActivityDetailsParser extends AbstractHuamiActivityDetailsPar
private void consumeAltitude(final ByteBuffer buf, final int length) {
consumeTimestampOffset(buf);
final int altitudeRaw = buf.getInt();
// Check for Balance 2 format with validity flag
final double newAltitude;
if (length == 7) {
@@ -453,7 +482,7 @@ public class ZeppOsActivityDetailsParser extends AbstractHuamiActivityDetailsPar
return this.expectedLength;
}
public static Type fromCode(final byte code) {
public static Type fromCode(final int code) {
for (final Type type : values()) {
if (type.getCode() == code) {
return type;