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//! Unbuffered connection API
use alloc::vec::Vec;
use core::num::NonZeroUsize;
use core::{fmt, mem};
#[cfg(feature = "std")]
use std::error::Error as StdError;
use super::UnbufferedConnectionCommon;
use crate::client::ClientConnectionData;
use crate::msgs::deframer::buffers::{BufferProgress, DeframerSliceBuffer};
use crate::server::ServerConnectionData;
use crate::Error;
impl UnbufferedConnectionCommon<ClientConnectionData> {
/// Processes the TLS records in `incoming_tls` buffer until a new [`UnbufferedStatus`] is
/// reached.
pub fn process_tls_records<'c, 'i>(
&'c mut self,
incoming_tls: &'i mut [u8],
) -> UnbufferedStatus<'c, 'i, ClientConnectionData> {
self.process_tls_records_common(incoming_tls, |_| None, |_, _, ()| unreachable!())
}
}
impl UnbufferedConnectionCommon<ServerConnectionData> {
/// Processes the TLS records in `incoming_tls` buffer until a new [`UnbufferedStatus`] is
/// reached.
pub fn process_tls_records<'c, 'i>(
&'c mut self,
incoming_tls: &'i mut [u8],
) -> UnbufferedStatus<'c, 'i, ServerConnectionData> {
self.process_tls_records_common(
incoming_tls,
|conn| conn.pop_early_data(),
|conn, incoming_tls, chunk| ReadEarlyData::new(conn, incoming_tls, chunk).into(),
)
}
}
impl<Data> UnbufferedConnectionCommon<Data> {
fn process_tls_records_common<'c, 'i, T>(
&'c mut self,
incoming_tls: &'i mut [u8],
mut check: impl FnMut(&mut Self) -> Option<T>,
execute: impl FnOnce(&'c mut Self, &'i mut [u8], T) -> ConnectionState<'c, 'i, Data>,
) -> UnbufferedStatus<'c, 'i, Data> {
let mut buffer = DeframerSliceBuffer::new(incoming_tls);
let mut buffer_progress = BufferProgress::default();
let (discard, state) = loop {
if let Some(value) = check(self) {
break (buffer.pending_discard(), execute(self, incoming_tls, value));
}
if let Some(chunk) = self
.core
.common_state
.received_plaintext
.pop()
{
break (
buffer.pending_discard(),
ReadTraffic::new(self, incoming_tls, chunk).into(),
);
}
if let Some(chunk) = self
.core
.common_state
.sendable_tls
.pop()
{
break (
buffer.pending_discard(),
EncodeTlsData::new(self, chunk).into(),
);
}
let deframer_output =
match self
.core
.deframe(None, buffer.filled_mut(), &mut buffer_progress)
{
Err(err) => {
buffer.queue_discard(buffer_progress.take_discard());
return UnbufferedStatus {
discard: buffer.pending_discard(),
state: Err(err),
};
}
Ok(r) => r,
};
if let Some(msg) = deframer_output {
let mut state =
match mem::replace(&mut self.core.state, Err(Error::HandshakeNotComplete)) {
Ok(state) => state,
Err(e) => {
buffer.queue_discard(buffer_progress.take_discard());
self.core.state = Err(e.clone());
return UnbufferedStatus {
discard: buffer.pending_discard(),
state: Err(e),
};
}
};
match self.core.process_msg(msg, state, None) {
Ok(new) => state = new,
Err(e) => {
buffer.queue_discard(buffer_progress.take_discard());
self.core.state = Err(e.clone());
return UnbufferedStatus {
discard: buffer.pending_discard(),
state: Err(e),
};
}
}
buffer.queue_discard(buffer_progress.take_discard());
self.core.state = Ok(state);
} else if self.wants_write {
break (
buffer.pending_discard(),
TransmitTlsData { conn: self }.into(),
);
} else if self
.core
.common_state
.has_received_close_notify
{
break (buffer.pending_discard(), ConnectionState::Closed);
} else if self
.core
.common_state
.may_send_application_data
{
break (
buffer.pending_discard(),
ConnectionState::WriteTraffic(WriteTraffic { conn: self }),
);
} else {
break (buffer.pending_discard(), ConnectionState::BlockedHandshake);
}
};
UnbufferedStatus {
discard,
state: Ok(state),
}
}
}
/// The current status of the `UnbufferedConnection*`
#[must_use]
#[derive(Debug)]
pub struct UnbufferedStatus<'c, 'i, Data> {
/// Number of bytes to discard
///
/// After the `state` field of this object has been handled, `discard` bytes must be
/// removed from the *front* of the `incoming_tls` buffer that was passed to
/// the [`UnbufferedConnectionCommon::process_tls_records`] call that returned this object.
///
/// This discard operation MUST happen *before*
/// [`UnbufferedConnectionCommon::process_tls_records`] is called again.
pub discard: usize,
/// The current state of the handshake process
///
/// This value MUST be handled prior to calling
/// [`UnbufferedConnectionCommon::process_tls_records`] again. See the documentation on the
/// variants of [`ConnectionState`] for more details.
pub state: Result<ConnectionState<'c, 'i, Data>, Error>,
}
/// The state of the [`UnbufferedConnectionCommon`] object
#[non_exhaustive] // for forwards compatibility; to support caller-side certificate verification
pub enum ConnectionState<'c, 'i, Data> {
/// One, or more, application data records are available
///
/// See [`ReadTraffic`] for more details on how to use the enclosed object to access
/// the received data.
ReadTraffic(ReadTraffic<'c, 'i, Data>),
/// Connection has been cleanly closed by the peer
Closed,
/// One, or more, early (RTT-0) data records are available
ReadEarlyData(ReadEarlyData<'c, 'i, Data>),
/// A Handshake record is ready for encoding
///
/// Call [`EncodeTlsData::encode`] on the enclosed object, providing an `outgoing_tls`
/// buffer to store the encoding
EncodeTlsData(EncodeTlsData<'c, Data>),
/// Previously encoded handshake records need to be transmitted
///
/// Transmit the contents of the `outgoing_tls` buffer that was passed to previous
/// [`EncodeTlsData::encode`] calls to the peer.
///
/// After transmitting the contents, call [`TransmitTlsData::done`] on the enclosed object.
/// The transmitted contents MUST not be sent to the peer more than once so they SHOULD be
/// discarded at this point.
///
/// At some stages of the handshake process, it's possible to send application-data alongside
/// handshake records. Call [`TransmitTlsData::may_encrypt_app_data`] on the enclosed
/// object to probe if that's allowed.
TransmitTlsData(TransmitTlsData<'c, Data>),
/// More TLS data is needed to continue with the handshake
///
/// Request more data from the peer and append the contents to the `incoming_tls` buffer that
/// was passed to [`UnbufferedConnectionCommon::process_tls_records`].
BlockedHandshake,
/// The handshake process has been completed.
///
/// [`WriteTraffic::encrypt`] can be called on the enclosed object to encrypt application
/// data into an `outgoing_tls` buffer. Similarly, [`WriteTraffic::queue_close_notify`] can
/// be used to encrypt a close_notify alert message into a buffer to signal the peer that the
/// connection is being closed. Data written into `outgoing_buffer` by either method MAY be
/// transmitted to the peer during this state.
///
/// Once this state has been reached, data MAY be requested from the peer and appended to an
/// `incoming_tls` buffer that will be passed to a future
/// [`UnbufferedConnectionCommon::process_tls_records`] invocation. When enough data has been
/// appended to `incoming_tls`, [`UnbufferedConnectionCommon::process_tls_records`] will yield
/// the [`ConnectionState::ReadTraffic`] state.
WriteTraffic(WriteTraffic<'c, Data>),
}
impl<'c, 'i, Data> From<ReadTraffic<'c, 'i, Data>> for ConnectionState<'c, 'i, Data> {
fn from(v: ReadTraffic<'c, 'i, Data>) -> Self {
Self::ReadTraffic(v)
}
}
impl<'c, 'i, Data> From<ReadEarlyData<'c, 'i, Data>> for ConnectionState<'c, 'i, Data> {
fn from(v: ReadEarlyData<'c, 'i, Data>) -> Self {
Self::ReadEarlyData(v)
}
}
impl<'c, 'i, Data> From<EncodeTlsData<'c, Data>> for ConnectionState<'c, 'i, Data> {
fn from(v: EncodeTlsData<'c, Data>) -> Self {
Self::EncodeTlsData(v)
}
}
impl<'c, 'i, Data> From<TransmitTlsData<'c, Data>> for ConnectionState<'c, 'i, Data> {
fn from(v: TransmitTlsData<'c, Data>) -> Self {
Self::TransmitTlsData(v)
}
}
impl<Data> fmt::Debug for ConnectionState<'_, '_, Data> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
Self::ReadTraffic(..) => f.debug_tuple("ReadTraffic").finish(),
Self::Closed => write!(f, "Closed"),
Self::ReadEarlyData(..) => f.debug_tuple("ReadEarlyData").finish(),
Self::EncodeTlsData(..) => f.debug_tuple("EncodeTlsData").finish(),
Self::TransmitTlsData(..) => f
.debug_tuple("TransmitTlsData")
.finish(),
Self::BlockedHandshake => f
.debug_tuple("BlockedHandshake")
.finish(),
Self::WriteTraffic(..) => f.debug_tuple("WriteTraffic").finish(),
}
}
}
/// Application data is available
pub struct ReadTraffic<'c, 'i, Data> {
_conn: &'c mut UnbufferedConnectionCommon<Data>,
// for forwards compatibility; to support in-place decryption in the future
_incoming_tls: &'i mut [u8],
chunk: Vec<u8>,
taken: bool,
}
impl<'c, 'i, Data> ReadTraffic<'c, 'i, Data> {
fn new(
_conn: &'c mut UnbufferedConnectionCommon<Data>,
_incoming_tls: &'i mut [u8],
chunk: Vec<u8>,
) -> Self {
Self {
_conn,
_incoming_tls,
chunk,
taken: false,
}
}
/// Decrypts and returns the next available app-data record
// TODO deprecate in favor of `Iterator` implementation, which requires in-place decryption
pub fn next_record(&mut self) -> Option<Result<AppDataRecord<'_>, Error>> {
if self.taken {
None
} else {
self.taken = true;
Some(Ok(AppDataRecord {
discard: 0,
payload: &self.chunk,
}))
}
}
/// Returns the payload size of the next app-data record *without* decrypting it
///
/// Returns `None` if there are no more app-data records
pub fn peek_len(&self) -> Option<NonZeroUsize> {
if self.taken {
None
} else {
NonZeroUsize::new(self.chunk.len())
}
}
}
/// Early application-data is available.
pub struct ReadEarlyData<'c, 'i, Data> {
_conn: &'c mut UnbufferedConnectionCommon<Data>,
// for forwards compatibility; to support in-place decryption in the future
_incoming_tls: &'i mut [u8],
chunk: Vec<u8>,
taken: bool,
}
impl<'c, 'i, Data> ReadEarlyData<'c, 'i, Data> {
fn new(
_conn: &'c mut UnbufferedConnectionCommon<Data>,
_incoming_tls: &'i mut [u8],
chunk: Vec<u8>,
) -> Self {
Self {
_conn,
_incoming_tls,
chunk,
taken: false,
}
}
}
impl<'c, 'i> ReadEarlyData<'c, 'i, ServerConnectionData> {
/// decrypts and returns the next available app-data record
// TODO deprecate in favor of `Iterator` implementation, which requires in-place decryption
pub fn next_record(&mut self) -> Option<Result<AppDataRecord<'_>, Error>> {
if self.taken {
None
} else {
self.taken = true;
Some(Ok(AppDataRecord {
discard: 0,
payload: &self.chunk,
}))
}
}
/// returns the payload size of the next app-data record *without* decrypting it
///
/// returns `None` if there are no more app-data records
pub fn peek_len(&self) -> Option<NonZeroUsize> {
if self.taken {
None
} else {
NonZeroUsize::new(self.chunk.len())
}
}
}
/// A decrypted application-data record
pub struct AppDataRecord<'i> {
/// Number of additional bytes to discard
///
/// This number MUST be added to the value of [`UnbufferedStatus.discard`] *prior* to the
/// discard operation. See [`UnbufferedStatus.discard`] for more details
pub discard: usize,
/// The payload of the app-data record
pub payload: &'i [u8],
}
/// Allows encrypting app-data
pub struct WriteTraffic<'c, Data> {
conn: &'c mut UnbufferedConnectionCommon<Data>,
}
impl<Data> WriteTraffic<'_, Data> {
/// Encrypts `application_data` into the `outgoing_tls` buffer
///
/// Returns the number of bytes that were written into `outgoing_tls`, or an error if
/// the provided buffer is too small. In the error case, `outgoing_tls` is not modified
pub fn encrypt(
&mut self,
application_data: &[u8],
outgoing_tls: &mut [u8],
) -> Result<usize, EncryptError> {
self.conn
.core
.maybe_refresh_traffic_keys();
self.conn
.core
.common_state
.write_plaintext(application_data.into(), outgoing_tls)
}
/// Encrypts a close_notify warning alert in `outgoing_tls`
///
/// Returns the number of bytes that were written into `outgoing_tls`, or an error if
/// the provided buffer is too small. In the error case, `outgoing_tls` is not modified
pub fn queue_close_notify(&mut self, outgoing_tls: &mut [u8]) -> Result<usize, EncryptError> {
self.conn
.core
.common_state
.eager_send_close_notify(outgoing_tls)
}
/// Arranges for a TLS1.3 `key_update` to be sent.
///
/// This consumes the `WriteTraffic` state: to actually send the message,
/// call [`UnbufferedConnectionCommon::process_tls_records`] again which will
/// return a `ConnectionState::EncodeTlsData` that emits the `key_update`
/// message.
///
/// See [`ConnectionCommon::refresh_traffic_keys()`] for full documentation,
/// including why you might call this and in what circumstances it will fail.
///
/// [`ConnectionCommon::refresh_traffic_keys()`]: crate::ConnectionCommon::refresh_traffic_keys
pub fn refresh_traffic_keys(self) -> Result<(), Error> {
self.conn.core.refresh_traffic_keys()
}
}
/// A handshake record must be encoded
pub struct EncodeTlsData<'c, Data> {
conn: &'c mut UnbufferedConnectionCommon<Data>,
chunk: Option<Vec<u8>>,
}
impl<'c, Data> EncodeTlsData<'c, Data> {
fn new(conn: &'c mut UnbufferedConnectionCommon<Data>, chunk: Vec<u8>) -> Self {
Self {
conn,
chunk: Some(chunk),
}
}
/// Encodes a handshake record into the `outgoing_tls` buffer
///
/// Returns the number of bytes that were written into `outgoing_tls`, or an error if
/// the provided buffer is too small. In the error case, `outgoing_tls` is not modified
pub fn encode(&mut self, outgoing_tls: &mut [u8]) -> Result<usize, EncodeError> {
let chunk = match self.chunk.take() {
Some(chunk) => chunk,
None => return Err(EncodeError::AlreadyEncoded),
};
let required_size = chunk.len();
if required_size > outgoing_tls.len() {
self.chunk = Some(chunk);
Err(InsufficientSizeError { required_size }.into())
} else {
let written = chunk.len();
outgoing_tls[..written].copy_from_slice(&chunk);
self.conn.wants_write = true;
Ok(written)
}
}
}
/// Previously encoded TLS data must be transmitted
pub struct TransmitTlsData<'c, Data> {
pub(crate) conn: &'c mut UnbufferedConnectionCommon<Data>,
}
impl<Data> TransmitTlsData<'_, Data> {
/// Signals that the previously encoded TLS data has been transmitted
pub fn done(self) {
self.conn.wants_write = false;
}
/// Returns an adapter that allows encrypting application data
///
/// If allowed at this stage of the handshake process
pub fn may_encrypt_app_data(&mut self) -> Option<WriteTraffic<'_, Data>> {
if self
.conn
.core
.common_state
.may_send_application_data
{
Some(WriteTraffic { conn: self.conn })
} else {
None
}
}
}
/// Errors that may arise when encoding a handshake record
#[derive(Debug)]
pub enum EncodeError {
/// Provided buffer was too small
InsufficientSize(InsufficientSizeError),
/// The handshake record has already been encoded; do not call `encode` again
AlreadyEncoded,
}
impl From<InsufficientSizeError> for EncodeError {
fn from(v: InsufficientSizeError) -> Self {
Self::InsufficientSize(v)
}
}
impl fmt::Display for EncodeError {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
Self::InsufficientSize(InsufficientSizeError { required_size }) => write!(
f,
"cannot encode due to insufficient size, {} bytes are required",
required_size
),
Self::AlreadyEncoded => "cannot encode, data has already been encoded".fmt(f),
}
}
}
#[cfg(feature = "std")]
impl StdError for EncodeError {}
/// Errors that may arise when encrypting application data
#[derive(Debug)]
pub enum EncryptError {
/// Provided buffer was too small
InsufficientSize(InsufficientSizeError),
/// Encrypter has been exhausted
EncryptExhausted,
}
impl From<InsufficientSizeError> for EncryptError {
fn from(v: InsufficientSizeError) -> Self {
Self::InsufficientSize(v)
}
}
impl fmt::Display for EncryptError {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
Self::InsufficientSize(InsufficientSizeError { required_size }) => write!(
f,
"cannot encrypt due to insufficient size, {required_size} bytes are required"
),
Self::EncryptExhausted => f.write_str("encrypter has been exhausted"),
}
}
}
#[cfg(feature = "std")]
impl StdError for EncryptError {}
/// Provided buffer was too small
#[derive(Clone, Copy, Debug)]
pub struct InsufficientSizeError {
/// buffer must be at least this size
pub required_size: usize,
}