UDP Protocol v1
The UDP protocol is more complex than TCP since we must implement reliability to ensure no packets are lost, but the general concept of wrapping the fastboot protocol is the same.

Overview:

As with TCP, the device will listen on UDP port 5554.
Maximum UDP packet size is negotiated during initialization.
The host drives all communication; the device may only send a packet as a response to a host packet.
If the host does not receive a response in 500ms it will re-transmit.
UDP Packet format
+----------+----+-------+-------+--------------------+
| Byte #   | 0  |   1   | 2 - 3 |  4+                |
+----------+----+-------+-------+--------------------+
| Contents | ID | Flags | Seq # | Data               |
+----------+----+-------+-------+--------------------+

ID      Packet ID:
          0x00: Error.
          0x01: Query.
          0x02: Initialization.
          0x03: Fastboot.

        Packet types are described in more detail below.

Flags   Packet flags: 0 0 0 0 0 0 0 C
          C=1 indicates a continuation packet; the data is too large and will
              continue in the next packet.

          Remaining bits are reserved for future use and must be set to 0.

Seq #   2-byte packet sequence number (big-endian). The host will increment
        this by 1 with each new packet, and the device must provide the
        corresponding sequence number in the response packets.

Data    Packet data, not present in all packets.
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