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//! Write packets to a stream.
use std::{
fmt::Debug,
io::{self, Read},
};
use azalea_buf::AzaleaWriteVar;
use azalea_crypto::Aes128CfbEnc;
use flate2::{Compression, bufread::ZlibEncoder};
use thiserror::Error;
use tokio::io::{AsyncWrite, AsyncWriteExt};
use tracing::trace;
use crate::{packets::ProtocolPacket, read::MAXIMUM_UNCOMPRESSED_LENGTH};
pub async fn write_packet<P, W>(
packet: &P,
stream: &mut W,
compression_threshold: Option<u32>,
cipher: &mut Option<Aes128CfbEnc>,
) -> io::Result<()>
where
P: ProtocolPacket + Debug,
W: AsyncWrite + Unpin + Send,
{
trace!("Sending packet: {packet:?}");
let raw_packet = serialize_packet(packet).unwrap();
write_raw_packet(&raw_packet, stream, compression_threshold, cipher).await
}
pub fn serialize_packet<P: ProtocolPacket + Debug>(
packet: &P,
) -> Result<Box<[u8]>, PacketEncodeError> {
let mut buf = Vec::new();
packet.id().azalea_write_var(&mut buf)?;
packet.write(&mut buf)?;
if buf.len() > MAXIMUM_UNCOMPRESSED_LENGTH as usize {
return Err(PacketEncodeError::TooBig {
actual: buf.len(),
maximum: MAXIMUM_UNCOMPRESSED_LENGTH as usize,
packet_string: format!("{packet:?}"),
});
}
Ok(buf.into_boxed_slice())
}
pub async fn write_raw_packet<W>(
raw_packet: &[u8],
stream: &mut W,
compression_threshold: Option<u32>,
cipher: &mut Option<Aes128CfbEnc>,
) -> io::Result<()>
where
W: AsyncWrite + Unpin + Send,
{
let network_packet = encode_to_network_packet(raw_packet, compression_threshold, cipher);
stream.write_all(&network_packet).await
}
pub fn encode_to_network_packet(
raw_packet: &[u8],
compression_threshold: Option<u32>,
cipher: &mut Option<Aes128CfbEnc>,
) -> Vec<u8> {
trace!("Writing raw packet: {raw_packet:?}");
let mut raw_packet = raw_packet.to_vec();
if let Some(threshold) = compression_threshold {
raw_packet = compression_encoder(&raw_packet, threshold).unwrap();
}
raw_packet = frame_prepender(raw_packet).unwrap();
// if we were given a cipher, encrypt the packet
if let Some(cipher) = cipher {
azalea_crypto::encrypt_packet(cipher, &mut raw_packet);
}
raw_packet
}
pub fn compression_encoder(
data: &[u8],
compression_threshold: u32,
) -> Result<Vec<u8>, PacketCompressError> {
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();
0_u32.azalea_write_var(&mut buf)?;
io::Write::write_all(&mut buf, data)?;
Ok(buf)
} else {
// otherwise, compress
let mut deflater = ZlibEncoder::new(data, Compression::default());
// write deflated data to buf
let mut compressed_data = Vec::new();
deflater.read_to_end(&mut compressed_data)?;
// prepend the length
let mut len_prepended_compressed_data = Vec::new();
(data.len() as u32).azalea_write_var(&mut len_prepended_compressed_data)?;
len_prepended_compressed_data.append(&mut compressed_data);
Ok(len_prepended_compressed_data)
}
}
/// Prepend the length of the packet to it.
fn frame_prepender(mut data: Vec<u8>) -> Result<Vec<u8>, io::Error> {
let mut buf = Vec::new();
(data.len() as u32).azalea_write_var(&mut buf)?;
buf.append(&mut data);
Ok(buf)
}
#[derive(Debug, Error)]
pub enum PacketEncodeError {
#[error("{0}")]
Io(#[from] io::Error),
#[error("Packet too big (is {actual} bytes, should be less than {maximum}): {packet_string}")]
TooBig {
actual: usize,
maximum: usize,
packet_string: String,
},
}
#[derive(Debug, Error)]
pub enum PacketCompressError {
#[error("{0}")]
Io(#[from] io::Error),
}
|
