From 1d4c85b7327e467b69a023596276ae7a09c85569 Mon Sep 17 00:00:00 2001
From: Daniele Gobbetti <daniele+cb@gobbetti.name>
Date: Wed, 7 Aug 2024 14:58:26 +0200
Subject: [PATCH] Garmin: implement (some kind of) auth negotiation message

Blindly implemented based on the legacy vivomoveHR code, not tested against real devices.
---
 .../messages/AuthNegotiationMessage.java      | 59 +++++++++++++++++++
 .../devices/garmin/messages/GFDIMessage.java  |  1 +
 2 files changed, 60 insertions(+)
 create mode 100644 app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/garmin/messages/AuthNegotiationMessage.java

diff --git a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/garmin/messages/AuthNegotiationMessage.java b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/garmin/messages/AuthNegotiationMessage.java
new file mode 100644
index 000000000..8b307b94d
--- /dev/null
+++ b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/garmin/messages/AuthNegotiationMessage.java
@@ -0,0 +1,59 @@
+package nodomain.freeyourgadget.gadgetbridge.service.devices.garmin.messages;
+
+import org.apache.commons.lang3.EnumUtils;
+
+import java.util.EnumSet;
+
+public class AuthNegotiationMessage extends GFDIMessage {
+
+    private final int unknown;
+    private final EnumSet<AuthFlags> requestedAuthFlags;
+
+    public AuthNegotiationMessage(GarminMessage garminMessage, int unknown, EnumSet<AuthFlags> requestedAuthFlags) {
+        this.garminMessage = garminMessage;
+        this.unknown = unknown;
+        this.requestedAuthFlags = requestedAuthFlags;
+
+        LOG.info("Message {}, unkByte: {}, flags: {}", garminMessage, unknown, requestedAuthFlags);
+
+        this.statusMessage = getStatusMessage();
+    }
+
+    public static AuthNegotiationMessage parseIncoming(MessageReader reader, GarminMessage garminMessage) {
+
+        final int unk = reader.readByte();
+        final EnumSet<AuthFlags> authFlags = AuthFlags.fromBitMask(reader.readInt());
+
+        return new AuthNegotiationMessage(garminMessage, unk, authFlags);
+    }
+
+    @Override
+    protected boolean generateOutgoing() {
+
+        final MessageWriter writer = new MessageWriter(response);
+        writer.writeShort(0); // placeholder for packet size
+        writer.writeShort(this.garminMessage.getId());
+
+        //set all to 0 as we don't know what else to do
+        writer.writeByte(0);
+        writer.writeInt((int) EnumUtils.generateBitVector(AuthFlags.class, EnumSet.noneOf(AuthFlags.class)));
+
+        return true;
+    }
+
+    private enum AuthFlags {
+        UNK_00000001, //saw in logs
+        UNK_00000010,
+        UNK_00000100,
+        UNK_00001000,
+        UNK_00010000,
+        UNK_00100000,
+        UNK_01000000,
+        UNK_10000000,
+        ;
+
+        public static EnumSet<AuthFlags> fromBitMask(final int code) {
+            return EnumUtils.processBitVector(AuthFlags.class, code);
+        }
+    }
+}
diff --git a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/garmin/messages/GFDIMessage.java b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/garmin/messages/GFDIMessage.java
index 7cb5a4240..b1acb444c 100644
--- a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/garmin/messages/GFDIMessage.java
+++ b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/garmin/messages/GFDIMessage.java
@@ -116,6 +116,7 @@ public abstract class GFDIMessage {
         MUSIC_CONTROL_ENTITY_UPDATE(5049, MusicControlEntityUpdateMessage.class),
         CONFIGURATION(5050, ConfigurationMessage.class),
         CURRENT_TIME_REQUEST(5052, CurrentTimeRequestMessage.class),
+        AUTH_NEGOTIATION(5101, AuthNegotiationMessage.class)
         ;
         private final Class<? extends GFDIMessage> objectClass;
         private final int id;