added example for oneway pattern Xpsk1 (#186)

Co-authored-by: Jürgen Kleer <[email protected]>

examples/oneway.rs

@@ -0,0 +1,139 @@
+#![cfg_attr(
+    not(any(feature = "default-resolver", feature = "ring-accelerated",)),
+    allow(dead_code, unused_extern_crates, unused_imports)
+)]
+//! This is a barebones TCP Client/Server that establishes a `Noise_X` session, and sends
+//! an important message across the wire.
+//!
+//! # Usage
+//! Run the server a-like-a-so `cargo run --example oneway -- -s`, then run the client
+//! as `cargo run --example oneway` to see the magic happen.
+
+use hex::FromHex;
+use lazy_static::lazy_static;
+use snow::{params::NoiseParams, Builder, Keypair};
+use std::{
+    io::{self, Read, Write},
+    net::{TcpListener, TcpStream},
+};
+
+static SECRET: &[u8; 32] = b"i don't care for fidget spinners";
+lazy_static! {
+    static ref PARAMS: NoiseParams = "Noise_Xpsk1_25519_ChaChaPoly_BLAKE2s".parse().unwrap();
+    // The responder key is static in this example because the X pattern means
+    // the initiator has pre-handshake knowledge of the responder's public key
+    // (and of course both share the same psk `SECRET`)
+    static ref RESPONDER: Keypair = Keypair {
+        private: Vec::from_hex("52fbe3721d1adbe312d270ca2db5ce5bd39ddc206075f3a8f06d422619c8eb5d").expect("valid hex"),
+        public: Vec::from_hex("435ce8a8415ccd44de5e207581ac7207b416683028bcaecc9eb38d944e6f900c").expect("valid hex"),
+    };
+}
+
+#[cfg(any(feature = "default-resolver", feature = "ring-accelerated"))]
+fn main() {
+    let server_mode =
+        std::env::args().next_back().map_or(true, |arg| arg == "-s" || arg == "--server");
+
+    if server_mode {
+        run_server(&RESPONDER.private, SECRET);
+    } else {
+        run_client(&RESPONDER.public, SECRET);
+    }
+    println!("all done.");
+}
+
+#[cfg(any(feature = "default-resolver", feature = "ring-accelerated"))]
+fn run_server(private_key: &[u8], psk: &[u8; 32]) {
+    let mut buf = vec![0u8; 65535];
+
+    // Initialize our responder using a builder.
+    let builder = Builder::new(PARAMS.clone());
+    let mut noise = builder
+        .local_private_key(private_key)
+        .unwrap()
+        .psk(1, psk)
+        .unwrap()
+        .build_responder()
+        .unwrap();
+
+    // Wait on our client's arrival...
+    println!("listening on 127.0.0.1:9999");
+    let (mut stream, _) = TcpListener::bind("127.0.0.1:9999").unwrap().accept().unwrap();
+
+    // <- e, es, s, ss
+    noise.read_message(&recv(&mut stream).unwrap(), &mut buf).unwrap();
+
+    // This is a oneway handshake - the server does not have to send anything
+
+    // The remote static key (of the initiator) is now known
+    let client = hex::encode(noise.get_remote_static().unwrap());
+
+    // Transition the state machine into transport mode now that the handshake is complete.
+    let mut noise = noise.into_transport_mode().unwrap();
+
+    while let Ok(msg) = recv(&mut stream) {
+        let len = noise.read_message(&msg, &mut buf).unwrap();
+        println!("{client} said: {}", String::from_utf8_lossy(&buf[..len]));
+    }
+    println!("connection closed.");
+}
+
+#[cfg(any(feature = "default-resolver", feature = "ring-accelerated"))]
+fn run_client(responder_public_key: &[u8], psk: &[u8; 32]) {
+    let mut buf = vec![0u8; 65535];
+
+    // Initialize our initiator using a builder.
+    let builder = Builder::new(PARAMS.clone());
+    let private_key = &builder.generate_keypair().unwrap().private;
+    let mut noise = builder
+        .local_private_key(private_key)
+        .unwrap()
+        .remote_public_key(responder_public_key)
+        .unwrap()
+        .psk(1, psk)
+        .unwrap()
+        .build_initiator()
+        .unwrap();
+
+    // Connect to our server, which is hopefully listening.
+    let mut stream = TcpStream::connect("127.0.0.1:9999").unwrap();
+    println!("connected...");
+
+    // -> e, es, s, ss
+    let len = noise.write_message(&[], &mut buf).unwrap();
+    send(&mut stream, &buf[..len]);
+
+    // This is a oneway handshake - the respnder must not send anything
+
+    let mut noise = noise.into_transport_mode().unwrap();
+    println!("session established...");
+
+    // Get to the important business of sending secured data.
+    for _ in 0..10 {
+        let len = noise.write_message(b"HACK THE PLANET", &mut buf).unwrap();
+        send(&mut stream, &buf[..len]);
+    }
+    println!("notified server of intent to hack planet.");
+}
+
+/// Hyper-basic stream transport receiver. 16-bit BE size followed by payload.
+fn recv(stream: &mut TcpStream) -> io::Result<Vec<u8>> {
+    let mut msg_len_buf = [0u8; 2];
+    stream.read_exact(&mut msg_len_buf)?;
+    let msg_len = usize::from(u16::from_be_bytes(msg_len_buf));
+    let mut msg = vec![0u8; msg_len];
+    stream.read_exact(&mut msg[..])?;
+    Ok(msg)
+}
+
+/// Hyper-basic stream transport sender. 16-bit BE size followed by payload.
+fn send(stream: &mut TcpStream, buf: &[u8]) {
+    let len = u16::try_from(buf.len()).expect("message too large");
+    stream.write_all(&len.to_be_bytes()).unwrap();
+    stream.write_all(buf).unwrap();
+}
+
+#[cfg(not(any(feature = "default-resolver", feature = "ring-accelerated")))]
+fn main() {
+    panic!("Example must be compiled with some cryptographic provider.");
+}