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use crate::{mc_buf::Writable, packets::ProtocolPacket, read::MAXIMUM_UNCOMPRESSED_LENGTH};
use async_compression::tokio::bufread::ZlibEncoder;
use azalea_crypto::Aes128CfbEnc;
use std::fmt::Debug;
use tokio::io::{AsyncReadExt, AsyncWrite, AsyncWriteExt};
fn frame_prepender(data: &mut Vec<u8>) -> Result<Vec<u8>, String> {
let mut buf = Vec::new();
buf.write_varint(data.len() as i32)
.map_err(|e| e.to_string())?;
buf.append(data);
Ok(buf)
}
fn packet_encoder<P: ProtocolPacket + std::fmt::Debug>(packet: &P) -> Result<Vec<u8>, String> {
let mut buf = Vec::new();
buf.write_varint(packet.id() as i32)
.map_err(|e| e.to_string())?;
packet.write(&mut buf).map_err(|e| e.to_string())?;
if buf.len() > MAXIMUM_UNCOMPRESSED_LENGTH as usize {
return Err(format!(
"Packet too big (is {} bytes, should be less than {}): {:?}",
buf.len(),
MAXIMUM_UNCOMPRESSED_LENGTH,
packet
));
}
Ok(buf)
}
async fn compression_encoder(data: &[u8], compression_threshold: u32) -> Result<Vec<u8>, String> {
let n = data.len();
// if it's less than the compression threshold, don't compress
if n < compression_threshold as usize {
let mut buf = Vec::new();
buf.write_varint(0).map_err(|e| e.to_string())?;
buf.write_all(data).await.map_err(|e| e.to_string())?;
Ok(buf)
} else {
// otherwise, compress
let mut deflater = ZlibEncoder::new(data);
// write deflated data to buf
let mut buf = Vec::new();
deflater
.read_to_end(&mut buf)
.await
.map_err(|e| e.to_string())?;
Ok(buf)
}
}
pub async fn write_packet<P, W>(
packet: P,
stream: &mut W,
compression_threshold: Option<u32>,
cipher: &mut Option<Aes128CfbEnc>,
) where
P: ProtocolPacket + Debug,
W: AsyncWrite + Unpin + Send,
{
let mut buf = packet_encoder(&packet).unwrap();
if let Some(threshold) = compression_threshold {
buf = compression_encoder(&buf, threshold).await.unwrap();
}
buf = frame_prepender(&mut buf).unwrap();
// if we were given a cipher, encrypt the packet
if let Some(cipher) = cipher {
azalea_crypto::encrypt_packet(cipher, &mut buf);
}
stream.write_all(&buf).await.unwrap();
}
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