Add rust-echo-server

Author: nojima

rust-echo-server/Cargo.lock

@@ -0,0 +1,8 @@
+[package]
+name = "rust-echo-server"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

rust-echo-server/Cargo.toml

@@ -0,0 +1,47 @@
+use std::io::{self, BufRead, BufReader, Read, Write};
+use std::net::{TcpListener, TcpStream};
+use std::thread;
+
+const MAX_READ_SIZE: u64 = 1024 * 1024;
+
+fn handle_client(client: TcpStream) -> io::Result<()> {
+    let mut reader = BufReader::new(&client);
+    let mut buffer = String::new();
+
+    loop {
+        // read
+        buffer.clear();
+        let n = (&mut reader).take(MAX_READ_SIZE).read_line(&mut buffer)?;
+        if n == 0 {
+            return Ok(());
+        }
+
+        // write
+        (&client).write_all(buffer.as_bytes())?;
+    }
+}
+
+fn main() -> io::Result<()> {
+    let listener = TcpListener::bind("[::]:3000")?;
+    eprintln!("server started on port 3000");
+
+    for stream in listener.incoming() {
+        let stream = match stream {
+            Ok(x) => x,
+            Err(e) => {
+                eprintln!("failed to accept connection: {e}");
+                continue;
+            }
+        };
+
+        thread::spawn(move || {
+            eprintln!("connection accepted");
+            if let Err(e) = handle_client(stream) {
+                eprintln!("failed to handle client: {e}");
+                return;
+            }
+            eprintln!("connection done");
+        });
+    }
+    Ok(())
+}