Maybe a NIT. But allocate the full buffer length.

[vDorst]

I am not sure how many times this is called?
I think every new connection?
Also have the feeling that resizeing the buffer is always needed on IPv6 connection.
So just alloc the full buffer to prevent just an extra alloction call.

haproxy-protocol/src/lib.rs

Line 141 in f9f94e2

let mut buf = vec![0; 16];

Maybe update this part with.

    let mut buf = Vec::with_capacity(HDR_SIZE_LIMIT);
    buf.resize(10, 0);