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//! Utilities for reading and writing for the Minecraft protocol
use std::io::Cursor;
use byteorder::{BigEndian, ReadBytesExt, WriteBytesExt};
use tokio::io::AsyncReadExt;
// const MAX_VARINT_SIZE: u32 = 5;
// const MAX_VARLONG_SIZE: u32 = 10;
// const DEFAULT_NBT_QUOTA: u32 = 2097152;
const MAX_STRING_LENGTH: u16 = 32767;
// const MAX_COMPONENT_STRING_LENGTH: u32 = 262144;
pub async fn read_byte(buf: &mut Cursor<Vec<u8>>) -> Result<u8, String> {
match AsyncReadExt::read_u8(buf).await {
Ok(r) => Ok(r),
Err(_) => Err("Error reading byte".to_string()),
}
}
pub fn write_byte(buf: &mut Vec<u8>, n: u8) {
buf.write_u8(n).unwrap();
}
pub fn write_bytes(buf: &mut Vec<u8>, bytes: &[u8]) {
buf.extend_from_slice(bytes);
}
pub async fn read_varint(buf: &mut Cursor<Vec<u8>>) -> Result<u32, String> {
let mut value: u32 = 0;
let mut length: u32 = 0;
let mut current_byte: u8;
loop {
current_byte = read_byte(buf).await?;
value |= ((current_byte & 0x7F) as u32) << (length * 7);
length += 1;
if length > 5 {
return Err("VarInt too big".to_string());
}
if (value & 0x80) != 0x80 {
return Ok(value);
}
}
}
pub fn write_varint(buf: &mut Vec<u8>, mut n: u32) {
loop {
if (n & 0xFFFFFF80) == 0 {
write_byte(buf, n as u8);
return ();
}
write_byte(buf, (n & 0x7F | 0x80) as u8);
n >>= 7;
}
}
pub fn write_utf_with_len(buf: &mut Vec<u8>, string: &String, len: usize) {
if string.len() > len {
panic!(
"String too big (was {} bytes encoded, max {})",
string.len(),
len
);
}
write_varint(buf, string.len() as u32);
write_bytes(buf, string.as_bytes());
}
pub fn write_utf(buf: &mut Vec<u8>, string: &String) {
write_utf_with_len(buf, string, MAX_STRING_LENGTH as usize);
}
pub fn write_short(buf: &mut Vec<u8>, n: u16) {
buf.write_u16::<BigEndian>(n).unwrap();
}
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