use aes_gcm::{
Aes256Gcm, AesGcm, KeyInit,
aead::{Aead, OsRng, Payload, generic_array::GenericArray, rand_core::RngCore},
};
use async_std::{
future::timeout,
io::{ReadExt, WriteExt},
net::{TcpListener, TcpStream},
sync::Mutex,
task::{self, yield_now},
};
use std::pin::Pin;
use std::sync::mpsc::{Receiver, Sender, channel};
use std::time::SystemTime;
use std::{
collections::HashMap,
io::{Error, ErrorKind},
str::FromStr,
sync::Arc,
time::Duration,
};
#[derive(PartialEq, Debug)]
pub enum RequestType {
Authentication,
Message,
Ping,
}
pub struct Server {
aesgcm: AesGcm<
aes_gcm::aes::Aes256,
aes_gcm::aes::cipher::typenum::UInt<
aes_gcm::aes::cipher::typenum::UInt<
aes_gcm::aes::cipher::typenum::UInt<
aes_gcm::aes::cipher::typenum::UInt<
aes_gcm::aes::cipher::typenum::UTerm,
aes_gcm::aead::consts::B1,
>,
aes_gcm::aead::consts::B1,
>,
aes_gcm::aead::consts::B0,
>,
aes_gcm::aead::consts::B0,
>,
>,
message_handler: MessageHandler,
listener: Arc<TcpListener>,
}
pub type MessageHandler =
Arc<dyn Fn(Vec<u8>) -> Pin<Box<dyn Future<Output = Vec<u8>> + Send>> + Send + Sync + 'static>;
impl Server {
pub async fn new(
host: String,
password: [u8; 32],
message_handler: MessageHandler,
workers: usize,
) -> Result<(), Error> {
let aesgcm = Aes256Gcm::new(&GenericArray::from_slice(&password));
let listener = Arc::new(TcpListener::bind(&host).await?);
Server::start(
Arc::new(Server {
listener,
message_handler,
aesgcm,
}),
workers,
)
.await
}
pub async fn start(self: Arc<Server>, workers: usize) -> Result<(), std::io::Error> {
if workers < 1 {
return Err(std::io::Error::new(
ErrorKind::InvalidInput,
"Invalid workers count, the minimum is \"1\".",
));
}
let mut worker_list: Vec<(Arc<Mutex<usize>>, Sender<TcpStream>)> = Vec::new();
for _ in 0..workers {
let (sender, receiver): (Sender<TcpStream>, Receiver<TcpStream>) = channel();
let cc = Arc::new(Mutex::new(0));
worker_list.push((cc.clone(), sender));
let server = self.clone();
task::spawn(async move {
let mut connections: Vec<(TcpStream, u128, bool)> = Vec::new();
let mut connection_health: HashMap<u128, SystemTime> = HashMap::new();
let mut cc_changed = false;
loop {
if let Ok(stream) = receiver.try_recv() {
let num = {
let mut numba = [0u8; 16];
numba[..8].clone_from_slice(&OsRng::next_u64(&mut OsRng).to_be_bytes());
numba[8..].clone_from_slice(&OsRng::next_u64(&mut OsRng).to_be_bytes());
u128::from_be_bytes(numba)
};
connection_health.insert(num, SystemTime::now());
connections.push((stream, num, true));
cc_changed = true;
}
let mut delete: Vec<usize> = Vec::new();
let mut current: Option<usize> = None;
for (index, connection) in connections.iter_mut().enumerate() {
if !connection.2 {
continue;
}
if let Ok(dur) = connection_health.get(&connection.1).unwrap().elapsed() {
if dur.as_secs() > 60 {
delete.push(index);
connection.2 = false;
continue;
}
}
let stream = &mut connection.0;
let interaction_type = if let Ok(result) =
timeout(Duration::from_millis(10), async {
let mut buffer = [0u8; 1];
stream.read_exact(&mut buffer).await.map(|_| buffer[0])
})
.await
{
match result {
Ok(byte) => byte,
Err(_) => {
delete.push(index);
connection.2 = false;
continue;
}
}
} else {
continue;
};
connection_health.insert(connection.1, SystemTime::now());
match interaction_type {
1 => {
current = Some(index);
break;
}
2 => {
connection_health.insert(connection.1, SystemTime::now());
}
_ => {
continue;
}
}
}
if let Some(index) = current {
if let Some(connection) = connections.get_mut(index) {
let stream = &mut connection.0;
let message_size = match timeout(Duration::from_secs(5), async {
let mut bytes = [0u8; 8];
stream
.read_exact(&mut bytes)
.await
.map(|_| u64::from_be_bytes(bytes) as usize)
})
.await
{
Ok(Ok(size)) => size,
_ => {
delete.push(index);
connection.2 = false;
continue;
}
};
let payload = match timeout(Duration::from_secs(5), async {
let mut bytes = vec![0u8; message_size];
stream.read_exact(&mut bytes).await.map(|_| bytes)
})
.await
{
Ok(Ok(bytes)) => {
if bytes.len() < 12 {
delete.push(index);
connection.2 = false;
continue;
}
let nonce = GenericArray::from_slice(&bytes[..12]);
let ciphertext = Payload::from(&bytes[12..]);
match server.aesgcm.decrypt(nonce, ciphertext) {
Ok(decrypted) => decrypted,
Err(_) => {
delete.push(index);
connection.2 = false;
continue;
}
}
}
_ => {
delete.push(index);
connection.2 = false;
continue;
}
};
let response = (server.message_handler)(payload).await;
let nonce = {
let mut dest: [u8; 12] = [0u8; 12];
OsRng::fill_bytes(&mut OsRng, &mut dest);
dest
};
if let Ok(encrypted) = server
.aesgcm
.encrypt(&GenericArray::from_slice(&nonce), response.as_slice())
{
let length = nonce.len() + encrypted.len();
let size: [u8; 8] = (length as u64).to_be_bytes();
let mut response_payload = size.to_vec();
response_payload.extend_from_slice(&nonce);
response_payload.extend_from_slice(&encrypted);
if stream.write_all(&response_payload).await.is_err()
|| stream.flush().await.is_err()
{
delete.push(index);
connection.2 = false;
}
}
}
}
if delete.len() > 0 {
delete.sort_unstable_by(|a, b| b.cmp(a));
for i in delete {
if i < connections.len() {
let connection = connections.remove(i);
connection_health.remove(&connection.1);
cc_changed = true;
}
}
}
if cc_changed {
cc_changed = false;
*cc.lock().await = connections.len();
}
yield_now().await;
}
});
}
loop {
let (stream, _) = self.listener.accept().await?;
let mut stream = stream;
let mut request_type_buffer = [0u8; 1];
if let Err(_) = stream.read_exact(&mut request_type_buffer).await {
continue;
};
let request_type: RequestType = match u8::from_be_bytes(request_type_buffer) {
0 => RequestType::Authentication,
_ => {
continue;
}
};
if RequestType::Authentication == request_type {
let mut password: [u8; 156] = [0u8; 156];
if let Err(_) = stream.read_exact(&mut password).await {
continue;
} else {
let nonce = GenericArray::from_slice(&password[..12]);
let cipher = &password[12..];
let ciphertext = Payload::from(cipher);
if let Ok(_) = self.aesgcm.decrypt(nonce, ciphertext) {
let _ = stream.write_all(&[255u8]).await;
let _ = stream.flush().await;
let mut min_connections = usize::MAX;
let mut selected_worker = None;
for worker in &worker_list {
let count = *worker.0.lock().await;
if count < min_connections {
min_connections = count;
selected_worker = Some(&worker.1);
}
}
if let Some(sender) = selected_worker {
let _ = sender.send(stream);
}
} else {
yield_now().await;
}
}
}
}
}
}
pub struct Client {
stream: TcpStream,
aesgcm: Aes256Gcm,
}
impl Client {
pub async fn new(address: &str, password: [u8; 32]) -> Result<Client, Error> {
let address = match std::net::SocketAddr::from_str(address) {
Ok(a) => a,
Err(e) => return Err(Error::new(ErrorKind::Other, e.to_string())),
};
let mut stream = TcpStream::connect(&address).await?;
let mut payload = vec![];
payload.push(0u8);
let nonce = {
let mut dest: [u8; 12] = [0u8; 12];
OsRng::fill_bytes(&mut OsRng, &mut dest);
dest
};
let brick = {
let mut dest: [u8; 128] = [0u8; 128];
OsRng::fill_bytes(&mut OsRng, &mut dest);
dest
};
payload.extend_from_slice(&nonce);
let aesgcm = Aes256Gcm::new(&GenericArray::from_slice(&password));
match aesgcm.encrypt(
GenericArray::from_slice(&nonce),
Payload::from(brick.as_slice()),
) {
Ok(encrypted) => payload.extend_from_slice(&encrypted),
Err(e) => return Err(Error::new(ErrorKind::Other, e.to_string())),
}
stream.write_all(&payload).await?;
stream.flush().await?;
let mut response = [0u8; 1];
if let Err(_) = timeout(Duration::from_secs(5), stream.read_exact(&mut response)).await {
return Err(Error::new(ErrorKind::TimedOut, "Authentication timeout"));
}
let success = response[0] == 255;
if success {
return Ok(Client { stream, aesgcm });
}
Err(Error::new(ErrorKind::ConnectionRefused, "Invalid password"))
}
pub async fn message(&mut self, bytes: Vec<u8>) -> Result<Vec<u8>, Error> {
let nonce = {
let mut dest: [u8; 12] = [0u8; 12];
OsRng::fill_bytes(&mut OsRng, &mut dest);
dest
};
let encrypted = match self.aesgcm.encrypt(
GenericArray::from_slice(&nonce),
Payload::from(bytes.as_slice()),
) {
Ok(enc) => enc,
Err(e) => return Err(Error::new(ErrorKind::Other, e.to_string())),
};
let total_size = nonce.len() + encrypted.len();
let mut payload = Vec::new();
payload.push(1u8);
payload.extend_from_slice(&(total_size as u64).to_be_bytes());
payload.extend_from_slice(&nonce);
payload.extend_from_slice(&encrypted);
self.stream.write_all(&payload).await?;
self.stream.flush().await?;
let mut response_size_bytes = [0u8; 8];
self.stream.read_exact(&mut response_size_bytes).await?;
let response_size = u64::from_be_bytes(response_size_bytes) as usize;
let mut response_payload = vec![0u8; response_size];
self.stream.read_exact(&mut response_payload).await?;
if response_payload.len() < 12 {
return Err(Error::new(ErrorKind::Other, "Response too small"));
}
let response_nonce = GenericArray::from_slice(&response_payload[..12]);
let response_ciphertext = Payload::from(&response_payload[12..]);
match self.aesgcm.decrypt(response_nonce, response_ciphertext) {
Ok(decrypted) => Ok(decrypted),
Err(e) => Err(Error::new(ErrorKind::Other, e.to_string())),
}
}
pub async fn ping(&mut self) -> Result<(), Error> {
self.stream.write_all(&[2u8]).await?;
self.stream.flush().await?;
Ok(())
}
}