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use bytes::BytesMut;
use tracing::info;
/// A struct for reading large buffers.
pub(crate) struct BigBufReader {
/// The data buffer.
data: BytesMut,
/// The remaining data buffer.
remaining_data: Option<Vec<u8>>,
/// The target length of the data buffer.
target_len: Option<usize>,
/// The message header mark.
message_header_mark: u16,
/// The message tail mark.
message_tail_mark: u16,
}
impl BigBufReader {
/// Creates a new `BigBufReader` instance.
///
/// # Parameters
///
/// * `message_header_mark` - The message header mark.
/// * `message_tail_mark` - The message tail mark.
///
/// # Returns
///
/// A new `BigBufReader` instance.
pub(crate) fn new(message_header_mark: u16, message_tail_mark: u16) -> Self {
Self {
data: BytesMut::with_capacity(0),
remaining_data: None,
target_len: None,
message_header_mark,
message_tail_mark,
}
}
/// Forces the buffer to be cleared.
pub(crate) fn forced_clear(&mut self) {
self.data.clear();
self.remaining_data = None;
self.target_len = None;
}
/// Checks the data in the buffer.
pub(crate) fn check_data(&mut self) {
if let Some(target_len) = self.target_len {
if target_len > 5 {
if self.data.len() > 10 + target_len && self.data.len() > 12 {
let data;
if target_len != 0 && target_len >= 2 {
data = self.data.split_off(10 + target_len);
} else {
data = self.data.split_off(12);
}
self.data.clear();
self.target_len = None;
self.extend_from_slice(&data);
} else {
self.data.clear();
self.target_len = None;
if let Some(buf) = &self.remaining_data {
let buf = buf.clone();
self.remaining_data = None;
self.extend_from_slice(&buf);
}
}
} else {
self.data.clear();
self.target_len = None;
if let Some(buf) = &self.remaining_data {
let buf = buf.clone();
self.remaining_data = None;
self.extend_from_slice(&buf);
}
}
} else {
if !self.data.is_empty() {
self.data.clear();
}
if let Some(buf) = &self.remaining_data {
let buf = buf.clone();
self.remaining_data = None;
self.target_len = None;
self.extend_from_slice(&buf);
}
}
}
/// Checks if the buffer is empty.
///
/// # Returns
///
/// `true` if the buffer is empty, `false` otherwise.
pub(crate) fn is_empty(&self) -> bool {
self.data.is_empty()
}
/// Gets the length of the next buffer to be extended.
///
/// # Returns
///
/// The length of the next buffer to be extended, or `None` if the buffer is already complete.
pub(crate) fn get_next_extend_buf_len(&mut self) -> Option<usize> {
if let Some(target_len) = self.target_len {
let len = self.data.len();
if len < target_len + 10 {
return Some(target_len + 10 - len);
}
}
None
}
/// Checks if the buffer is complete.
///
/// # Returns
///
/// `true` if the buffer is complete, `false` otherwise.
pub(crate) fn is_complete(&mut self) -> bool {
if let Some(target_len) = self.target_len {
if target_len <= 5 && self.data.len() >= 7 {
self.check_data();
if self.target_len.is_none() {
return false;
}
}
if !self.is_empty()
&& self.data.len() >= 10 + target_len.try_into().unwrap_or(0)
&& self.data.len() >= 12
&& u16::from_be_bytes([
self.data[10 + target_len - 2],
self.data[10 + target_len - 1],
]) == self.message_tail_mark
{
return true;
}
}
false
}
/// Gets the data from the buffer.
///
/// # Returns
///
/// The data from the buffer.
pub(crate) fn get_data(&mut self) -> Vec<u8> {
let result = self.data[10..self.target_len.unwrap() + 8].to_vec();
self.check_data();
result
}
/// Extends the buffer with the given slice.
///
/// # Parameters
///
/// * `buf` - The slice to extend the buffer with.
pub(crate) fn extend_from_slice(&mut self, buf: &[u8]) {
let buf_len = buf.len();
if !self.is_complete() {
let next_len = self.get_next_extend_buf_len();
if next_len.is_none() || next_len.unwrap() >= buf_len {
self.data.extend_from_slice(buf);
} else {
self.data.extend_from_slice(&buf[0..next_len.unwrap()]);
let bytes_mut = &buf[next_len.unwrap()..buf_len];
if self.remaining_data.is_none() {
self.remaining_data = Some(bytes_mut.to_vec());
} else {
if let Some(source_bytes_mut) = &self.remaining_data {
let mut data = source_bytes_mut.clone();
data.extend_from_slice(&bytes_mut);
self.remaining_data = Some(data)
}
}
}
if let Some(target_len) = self.target_len {
if target_len <= 5 && self.data.len() >= 7 {
self.check_data();
}
}
if self.target_len.is_none() {
let data_len = self.data.len();
if data_len >= 2 {
let header_mark =
u16::from_be_bytes([self.data[0].clone(), self.data[1].clone()]);
if header_mark == self.message_header_mark {
if data_len >= 10 {
let msg_len = u64::from_be_bytes([
self.data[2].clone(),
self.data[3].clone(),
self.data[4].clone(),
self.data[5].clone(),
self.data[6].clone(),
self.data[7].clone(),
self.data[8].clone(),
self.data[9].clone(),
]);
self.target_len = Some(msg_len.try_into().unwrap_or(5));
}
} else {
self.forced_clear();
}
}
}
} else {
self.remaining_data = Some(buf.to_vec());
}
}
}