noxtls 0.2.11

TLS/DTLS protocol and connection state machine for the noxtls Rust stack.
Documentation 
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// Copyright (c) 2019-2026, Argenox Technologies LLC
// All rights reserved.
//
// SPDX-License-Identifier: GPL-2.0-only OR LicenseRef-Argenox-Commercial-License

//! Async TLS 1.3 client handshake over [`noxtls_io::transport::stream_async::AsyncByteStream`].

use crate::internal_alloc::Vec;
use crate::platform_bridge::noxtls_hmac_drbg_from_entropy;
use crate::protocol::{
    CipherSuite, Connection, RecordContentType, TlsRecordDeframer, TlsVersion,
    TLS_RECORD_HEADER_LEN,
};
type TransportResult<T> = core::result::Result<T, TransportError>;
use noxtls_core::{Error, Result as TlsResult};
use noxtls_io::transport::drive_async::{noxtls_read_record_async, noxtls_write_all_async};
use noxtls_io::transport::stream_async::AsyncByteStream;
use noxtls_io::transport::TransportError;
use noxtls_platform::EntropySource;

const TLS_RECORD_HANDSHAKE: u8 = 0x16;
const TLS_RECORD_APPLICATION_DATA: u8 = 0x17;
const TLS_RECORD_CHANGE_CIPHER_SPEC: u8 = 0x14;

fn tls_err<T>(result: TlsResult<T>) -> TransportResult<T> {
    result.map_err(|_| TransportError::IoFailed("tls protocol error"))
}
/// TLS 1.3 client configuration for [`noxtls_connect_tls13_async`].
pub struct AsyncTlsClientConfig {
    /// Cipher suites to offer (server picks one).
    pub cipher_suites: Vec<CipherSuite>,
}

impl Default for AsyncTlsClientConfig {
    fn default() -> Self {
        Self {
            cipher_suites: vec![
                CipherSuite::TlsAes256GcmSha384,
                CipherSuite::TlsAes128GcmSha256,
            ],
        }
    }
}

/// Established TLS 1.3 client session.
pub struct AsyncTls13Client<S> {
    stream: S,
    pub conn: Connection,
    deframer: TlsRecordDeframer,
}

impl<S: AsyncByteStream> AsyncTls13Client<S> {
    /// Sends an HTTP-style application payload and returns the sealed record bytes written.
    pub async fn write_application(&mut self, plaintext: &[u8]) -> TransportResult<()> {
        let packet = self
            .seal_client_application(plaintext)
            .map_err(|_| TransportError::IoFailed("seal failed"))?;
        noxtls_write_all_async(&mut self.stream, &packet).await
    }

    /// Reads and decrypts one client-readable application record from the peer.
    pub async fn read_application(&mut self) -> TransportResult<Vec<u8>> {
        let packet = noxtls_read_record_async(&mut self.stream, &mut self.deframer).await?;
        self.open_server_application(&packet)
            .map_err(|_| TransportError::IoFailed("open application failed"))
    }

    fn seal_client_application(&mut self, plaintext: &[u8]) -> TlsResult<Vec<u8>> {
        let inner_len = plaintext.len().saturating_add(1);
        let payload_len = inner_len.saturating_add(16);
        let mut aad = [0_u8; TLS_RECORD_HEADER_LEN];
        aad[0] = TLS_RECORD_APPLICATION_DATA;
        aad[1] = 0x03;
        aad[2] = 0x03;
        aad[3] = ((payload_len >> 8) & 0xff) as u8;
        aad[4] = (payload_len & 0xff) as u8;
        self.conn
            .noxtls_seal_record(plaintext, &aad)
            .map(|protected| {
                let mut packet =
                    Vec::with_capacity(TLS_RECORD_HEADER_LEN + protected.ciphertext.len());
                packet.extend_from_slice(&aad);
                packet.extend_from_slice(&protected.ciphertext);
                packet
            })
    }

    fn open_server_application(&mut self, packet: &[u8]) -> TlsResult<Vec<u8>> {
        let aad = Connection::noxtls_tls13_packet_header_aad(packet)?;
        let (plaintext, content_type) = self.conn.noxtls_open_tls13_record_packet(packet, &aad)?;
        if content_type != RecordContentType::ApplicationData.to_u8() {
            return Err(Error::ParseFailure("expected application_data"));
        }
        Ok(plaintext)
    }
}

/// Performs a minimal TLS 1.3 client handshake (no certificate validation).
pub async fn noxtls_connect_tls13_async<S: AsyncByteStream>(
    mut stream: S,
    _config: &AsyncTlsClientConfig,
    entropy: &mut dyn EntropySource,
) -> TransportResult<AsyncTls13Client<S>> {
    let mut conn = Connection::noxtls_new(TlsVersion::Tls13);
    let mut drbg = tls_err(noxtls_hmac_drbg_from_entropy(
        entropy,
        b"noxtls tls13 client",
    ))?;
    let client_hello = tls_err(conn.noxtls_send_client_hello_auto(&mut drbg))?;
    noxtls_write_all_async(&mut stream, &encode_handshake_record(&client_hello)?).await?;

    let mut deframer = TlsRecordDeframer::noxtls_new();
    let server_hello_record = noxtls_read_record_async(&mut stream, &mut deframer).await?;
    let server_hello = extract_payload_message(&server_hello_record, 0x02)?;
    tls_err(conn.noxtls_recv_server_hello(&server_hello))?;

    // Compatibility CCS from server (optional)
    if let Ok(ccs) = noxtls_read_record_async(&mut stream, &mut deframer).await {
        if ccs.first() != Some(&TLS_RECORD_CHANGE_CIPHER_SPEC) {
            // put back by pushing into deframer - simplified: only accept CCS here
            deframer.push(&ccs);
        }
    }

    tls_err(conn.noxtls_derive_handshake_secret())?;

    let encrypted = noxtls_read_record_async(&mut stream, &mut deframer).await?;
    let aad = tls_err(Connection::noxtls_tls13_packet_header_aad(&encrypted))?;
    let packets = [encrypted];
    tls_err(conn.noxtls_process_tls13_server_encrypted_handshake_flight(&packets, &aad))?;

    let client_finished = tls_err(conn.noxtls_prepare_tls13_client_finished_message())?;
    let finished_record = tls_err(seal_handshake_record(&mut conn, &client_finished))?;
    noxtls_write_all_async(&mut stream, &finished_record).await?;
    tls_err(conn.noxtls_activate_tls13_application_traffic_keys())?;

    Ok(AsyncTls13Client {
        stream,
        conn,
        deframer,
    })
}

fn encode_handshake_record(body: &[u8]) -> TransportResult<Vec<u8>> {
    let mut packet = Vec::with_capacity(TLS_RECORD_HEADER_LEN + body.len());
    packet.push(TLS_RECORD_HANDSHAKE);
    packet.extend_from_slice(&[0x03, 0x03]);
    packet.extend_from_slice(&(body.len() as u16).to_be_bytes());
    packet.extend_from_slice(body);
    Ok(packet)
}

fn extract_payload_message(record: &[u8], msg_type: u8) -> TransportResult<Vec<u8>> {
    if record.len() < TLS_RECORD_HEADER_LEN {
        return Err(TransportError::IoFailed("short record"));
    }
    let payload = &record[TLS_RECORD_HEADER_LEN..];
    if payload.first() != Some(&msg_type) {
        return Err(TransportError::IoFailed("wrong handshake type"));
    }
    Ok(payload.to_vec())
}

fn seal_handshake_record(conn: &mut Connection, handshake: &[u8]) -> TlsResult<Vec<u8>> {
    let inner_len = handshake.len().saturating_add(1);
    let payload_len = inner_len.saturating_add(16);
    let mut aad = [0_u8; TLS_RECORD_HEADER_LEN];
    aad[0] = TLS_RECORD_APPLICATION_DATA;
    aad[1] = 0x03;
    aad[2] = 0x03;
    aad[3] = ((payload_len >> 8) & 0xff) as u8;
    aad[4] = (payload_len & 0xff) as u8;
    conn.noxtls_seal_record(handshake, &aad).map(|p| {
        let mut out = Vec::with_capacity(TLS_RECORD_HEADER_LEN + p.ciphertext.len());
        out.extend_from_slice(&aad);
        out.extend_from_slice(&p.ciphertext);
        out
    })
}