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Reedyuk / blue-falcon

A Bluetooth kotlin multiplatform "Cross-Platform" library for iOS and Android
https://bluefalcon.dev
Apache License 2.0
340 stars 45 forks source link

Characteristic value string encoded with UTF-8 alters byte values #33

Closed ivannador closed 4 years ago

ivannador commented 4 years ago

Currently the BT characteristic value is represented as a String, which is encoded from byte[] (Android) and NSData (iOS) with UTF-8 encoding. This is OK if the characteristic value contains byte values in the UTF-8 charset but causes problems otherwise (replaces unknown byte value with the Unicode replacement character U+FFFD "�").

Example:

Characteristic value byte[] sent by GATT server: 102,-120,51,64
Characteristic value string encoded from the byte[]: f�3@
Characteristic value byte[] decoded from the string: 102,-17,-65,-67,51,64

In this specific case our device is sending 4 byte packets with little endian ordering. The value -120 is invalid in UTF-8.

I think it would be better to use a ByteArray as the characteristic value type. Then everyone can decide in their client code if it will be converted to String or used as a ByteArray.

Would this cause any problems? Does using String as value have other reasons I'm not seeing? If this works I'm more than happy to submit a PR.

Thanks!

Reedyuk commented 4 years ago

No, thats my bad, i was lazy and with my custom bluetooth device i was sending over string. Happy for you to put a PR in. Cheers.

ivannador commented 4 years ago

Oh, right. :) Submitted the PR.

ivannador commented 4 years ago

Thanks for the update. The new version is not on maven central though. The gradle.properties shows the previous version number.

Reedyuk commented 4 years ago

strange, let me do it again now.