How can I deserialize a bincode field without a given length

Question

So I'm trying to deserialize a message consisting of binary data (bincode), this binary isn't serialized by serde but I'm trying to use serde to deserialize it. However, the data send optionally has a raw data section at the end of which the length isn't prefixed but is guaranteed to be the rest of the message. Serde always expects a length. I can't add the length due to backwards compatability concerns with a system not made/designed by me, this compat is important. Is this possible to achieve with Serde and how would I go about doing that?

I've already looked at the docs for serde and bincode and couldn't find anything in there to help me.

Answer 1

bincode::deserialize_from lets you retain any trailing data in the input stream.

---

use serde::Deserialize;

#[derive(Deserialize, Debug)]
struct Data {
    q: String,
    r: i32,

    #[serde(skip)]
    trailing: Vec<u8>,
}

fn main() -> bincode::Result<()> {
    let bytes = [7, 0, 0, 0, 0, 0, 0, 0, 115, 117, 99, 99, 101, 115, 115, 227, 7, 0, 0, 3, 2, 1];

    let mut cursor = &bytes[..];
    let mut data: Data = bincode::deserialize_from(&mut cursor)?;
    data.trailing = cursor.to_owned();

    println!("{:#?}", data);
    Ok(())
}