Cleanup and make example code more rusty

examples/simple.rs

@@ -40,7 +40,7 @@ fn run_server() {
     let mut buf = vec![0u8; 65535];
 
     // Initialize our responder using a builder.
-    let builder: Builder<'_> = Builder::new(PARAMS.clone());
+    let builder = Builder::new(PARAMS.clone());
     let static_key = builder.generate_keypair().unwrap().private;
     let mut noise =
         builder.local_private_key(&static_key).psk(3, SECRET).build_responder().unwrap();
@@ -53,7 +53,7 @@ fn run_server() {
     noise.read_message(&recv(&mut stream).unwrap(), &mut buf).unwrap();
 
     // -> e, ee, s, es
-    let len = noise.write_message(&[0u8; 0], &mut buf).unwrap();
+    let len = noise.write_message(&[], &mut buf).unwrap();
     send(&mut stream, &buf[..len]);
 
     // <- s, se
@@ -74,7 +74,7 @@ fn run_client() {
     let mut buf = vec![0u8; 65535];
 
     // Initialize our initiator using a builder.
-    let builder: Builder<'_> = Builder::new(PARAMS.clone());
+    let builder = Builder::new(PARAMS.clone());
     let static_key = builder.generate_keypair().unwrap().private;
     let mut noise =
         builder.local_private_key(&static_key).psk(3, SECRET).build_initiator().unwrap();
@@ -109,16 +109,16 @@ fn run_client() {
 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 = ((msg_len_buf[0] as usize) << 8) + (msg_len_buf[1] as usize);
+    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 msg_len_buf = [(buf.len() >> 8) as u8, (buf.len() & 0xff) as u8];
-    stream.write_all(&msg_len_buf).unwrap();
+    let len = u16::try_from(buf.len()).expect("message too large");
+    stream.write_all(&len.to_be_bytes()).unwrap();
     stream.write_all(buf).unwrap();
 }