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use crate::tls::rustls::{
cipher::{MessageDecrypter, MessageEncrypter},
error::Error,
msgs::message::{BorrowedPlainMessage, OpaqueMessage, PlainMessage},
};
static SEQ_SOFT_LIMIT: u64 = 0xffff_ffff_ffff_0000u64;
static SEQ_HARD_LIMIT: u64 = 0xffff_ffff_ffff_fffeu64;
#[derive(PartialEq)]
enum DirectionState {
Invalid,
Prepared,
Active,
}
pub struct RecordLayer {
message_encrypter: Box<dyn MessageEncrypter>,
message_decrypter: Box<dyn MessageDecrypter>,
write_seq: u64,
read_seq: u64,
encrypt_state: DirectionState,
decrypt_state: DirectionState,
trial_decryption_len: Option<usize>,
}
impl RecordLayer {
pub fn new() -> Self {
Self {
message_encrypter: <dyn MessageEncrypter>::invalid(),
message_decrypter: <dyn MessageDecrypter>::invalid(),
write_seq: 0,
read_seq: 0,
encrypt_state: DirectionState::Invalid,
decrypt_state: DirectionState::Invalid,
trial_decryption_len: None,
}
}
pub fn is_encrypting(&self) -> bool {
self.encrypt_state == DirectionState::Active
}
pub fn is_decrypting(&self) -> bool {
self.decrypt_state == DirectionState::Active
}
pub fn doing_trial_decryption(&mut self, requested: usize) -> bool {
match self
.trial_decryption_len
.and_then(|value| value.checked_sub(requested))
{
Some(remaining) => {
self.trial_decryption_len = Some(remaining);
true
}
_ => false,
}
}
pub fn prepare_message_encrypter(&mut self, cipher: Box<dyn MessageEncrypter>) {
self.message_encrypter = cipher;
self.write_seq = 0;
self.encrypt_state = DirectionState::Prepared;
}
pub fn prepare_message_decrypter(&mut self, cipher: Box<dyn MessageDecrypter>) {
self.message_decrypter = cipher;
self.read_seq = 0;
self.decrypt_state = DirectionState::Prepared;
}
pub fn start_encrypting(&mut self) {
debug_assert!(self.encrypt_state == DirectionState::Prepared);
self.encrypt_state = DirectionState::Active;
}
pub fn start_decrypting(&mut self) {
debug_assert!(self.decrypt_state == DirectionState::Prepared);
self.decrypt_state = DirectionState::Active;
}
pub fn set_message_encrypter(&mut self, cipher: Box<dyn MessageEncrypter>) {
self.prepare_message_encrypter(cipher);
self.start_encrypting();
}
pub fn set_message_decrypter(&mut self, cipher: Box<dyn MessageDecrypter>) {
self.prepare_message_decrypter(cipher);
self.start_decrypting();
self.trial_decryption_len = None;
}
pub fn set_message_decrypter_with_trial_decryption(
&mut self,
cipher: Box<dyn MessageDecrypter>,
max_length: usize,
) {
self.prepare_message_decrypter(cipher);
self.start_decrypting();
self.trial_decryption_len = Some(max_length);
}
pub fn finish_trial_decryption(&mut self) {
self.trial_decryption_len = None;
}
pub fn wants_close_before_decrypt(&self) -> bool {
self.read_seq == SEQ_SOFT_LIMIT
}
pub fn wants_close_before_encrypt(&self) -> bool {
self.write_seq == SEQ_SOFT_LIMIT
}
pub fn encrypt_exhausted(&self) -> bool {
self.write_seq >= SEQ_HARD_LIMIT
}
pub fn decrypt_incoming(&mut self, encr: OpaqueMessage) -> Result<PlainMessage, Error> {
debug_assert!(self.is_decrypting());
let seq = self.read_seq;
let msg = self.message_decrypter.decrypt(encr, seq)?;
self.read_seq += 1;
Ok(msg)
}
pub fn encrypt_outgoing(&mut self, plain: BorrowedPlainMessage) -> OpaqueMessage {
debug_assert!(self.encrypt_state == DirectionState::Active);
assert!(!self.encrypt_exhausted());
let seq = self.write_seq;
self.write_seq += 1;
self.message_encrypter.encrypt(plain, seq).unwrap()
}
}
impl Default for RecordLayer {
fn default() -> Self {
Self::new()
}
}