initial commit

exercises/08_futures/01_async_fn/Cargo.toml

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+[package]
+name = "async_fn"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+anyhow = "1.0.83"
+tokio = { version = "1", features = ["full"] }

exercises/08_futures/01_async_fn/src/lib.rs

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+use tokio::net::TcpListener;
+
+// TODO: write an echo server that accepts incoming TCP connections and
+//  echoes the received data back to the client.
+//  `echo` should not return when it finishes processing a connection, but should
+//  continue to accept new connections.
+//
+// Hint: you should rely on `tokio`'s structs and methods to implement the echo server.
+// In particular:
+// - `tokio::net::TcpListener::accept` to process the next incoming connection
+// - `tokio::net::TcpStream::split` to obtain a reader and a writer from the socket
+// - `tokio::io::copy` to copy data from the reader to the writer
+pub async fn echo(listener: TcpListener) -> Result<(), anyhow::Error> {
+    todo!()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use tokio::io::{AsyncReadExt, AsyncWriteExt};
+
+    #[tokio::test]
+    async fn test_echo() {
+        let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
+        let addr = listener.local_addr().unwrap();
+        tokio::spawn(echo(listener));
+
+        let requests = vec!["hello", "world", "foo", "bar"];
+
+        for request in requests {
+            let mut socket = tokio::net::TcpStream::connect(addr).await.unwrap();
+            let (mut reader, mut writer) = socket.split();
+
+            // Send the request
+            writer.write_all(request.as_bytes()).await.unwrap();
+            // Close the write side of the socket
+            writer.shutdown().await.unwrap();
+
+            // Read the response
+            let mut buf = Vec::with_capacity(request.len());
+            reader.read_to_end(&mut buf).await.unwrap();
+            assert_eq!(&buf, request.as_bytes());
+        }
+    }
+}