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Commit a8c967d6 authored by Ying Hsu's avatar Ying Hsu
Browse files

floss: Support 128-bit UUID to shortest bytes array conversion 

get_shortest_bytes parses an 128-bit UUID into a byte array.
If an UUID value is in Bluetooth pre-allocated range, it will be converted into
shortest representation, either 16-bit or 32-bit UUID.

Bug: 251000212
Test: ./build.py --target test
Change-Id: I0ae13a59bb888ecc82f2fe5125303e67a8581341
parent 9c3630f6

system/gd/rust/linux/stack/src/uuid.rs

+59 −0
Original line number Diff line number Diff line
@@ -72,6 +72,10 @@ pub enum Profile { 
    CoordinatedSet,

}



// Unsigned integer representation of UUIDs.

pub const BASE_UUID_NUM: u128 = 0x0000000000001000800000805f9b34fbu128;

pub const BASE_UUID_MASK: u128 = !(0xffffffffu128 << 96);



/// Wraps a reference of Uuid128Bit, which is the raw array of bytes of UUID.

/// This is useful in implementing standard Rust traits which can't be implemented directly on

/// built-in types (Rust's Orphan Rule).
@@ -92,6 +96,14 @@ impl<'a> Display for KnownUuidWrapper<'a> { 
    }

}



/// Represents binary encoding of UUID in big-endian.

#[derive(Debug)]

pub enum UuidBytes {

    Uuid16Bit([u8; 2]),

    Uuid32Bit([u8; 4]),

    Uuid128Bit([u8; 16]),

}



pub struct UuidHelper {

    /// A list of enabled profiles on the system. These may be modified by policy.

    pub enabled_profiles: HashSet<Profile>,
@@ -214,6 +226,31 @@ impl UuidHelper { 


        Some(uuid)

    }



    /// Parses an 128-bit UUID into a byte array of shortest representation.

    pub fn get_shortest_bytes(uuid: &Uuid128Bit) -> UuidBytes {

        if UuidHelper::in_16bit_uuid_range(uuid) {

            return UuidBytes::Uuid16Bit([uuid[2], uuid[3]]);

        } else if UuidHelper::in_32bit_uuid_range(uuid) {

            return UuidBytes::Uuid32Bit([uuid[0], uuid[1], uuid[2], uuid[3]]);

        } else {

            return UuidBytes::Uuid128Bit(*uuid);

        }

    }



    /// Checks whether the UUID value is in the 16-bit Bluetooth UUID range.

    fn in_16bit_uuid_range(uuid: &Uuid128Bit) -> bool {

        if !UuidHelper::in_32bit_uuid_range(uuid) {

            return false;

        }

        uuid[0] == 0 && uuid[1] == 0

    }



    /// Checks whether the UUID value is in the 32-bit Bluetooth UUID range.

    fn in_32bit_uuid_range(uuid: &Uuid128Bit) -> bool {

        let num = u128::from_be_bytes(*uuid);

        (num & BASE_UUID_MASK) == BASE_UUID_NUM

    }

}



// Temporary util that covers only basic string conversion.
@@ -255,4 +292,26 @@ mod tests { 
            });

        }

    }



    #[test]

    fn test_get_shortest_bytes() {

        let uuid_16 = UuidHelper::from_string("0000fef3-0000-1000-8000-00805f9b34fb").unwrap();

        assert!(matches!(

            UuidHelper::get_shortest_bytes(&uuid_16),

            UuidBytes::Uuid16Bit([0xfe, 0xf3])

        ));



        let uuid_32 = UuidHelper::from_string("00112233-0000-1000-8000-00805f9b34fb").unwrap();

        assert!(matches!(

            UuidHelper::get_shortest_bytes(&uuid_32),

            UuidBytes::Uuid32Bit([0x00, 0x11, 0x22, 0x33])

        ));



        let uuid_128 = UuidHelper::from_string("00112233-4455-6677-8899-aabbccddeeff").unwrap();

        let exp_bytes: Vec<u8> = (0..16).map(|d| (d << 4) + d).collect();

        assert!(matches!(

            UuidHelper::get_shortest_bytes(&uuid_128),

            UuidBytes::Uuid128Bit(exp_bytes)

        ));

    }

}