feat(request-response): add modules for json and cbor messages

This patch adds two modules to `libp2p::request_response`:

- `cbor`
- `json`

Both define a `Behaviour` type-alias that comes with a `Codec` implementation which uses the respective `serde` crate to serialize and deserialize the messages.

Fixes #3905.

Pull-Request: #3952.

protocols/request-response/src/json.rs

@@ -0,0 +1,202 @@
+// Copyright 2023 Protocol Labs
+//
+// Permission is hereby granted, free of charge, to any person obtaining a
+// copy of this software and associated documentation files (the "Software"),
+// to deal in the Software without restriction, including without limitation
+// the rights to use, copy, modify, merge, publish, distribute, sublicense,
+// and/or sell copies of the Software, and to permit persons to whom the
+// Software is furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+// DEALINGS IN THE SOFTWARE.
+
+/// A request-response behaviour using [`serde_json`] for serializing and deserializing the messages.
+///
+/// # Example
+///
+/// ```
+/// # use libp2p_request_response::{json, ProtocolSupport, self as request_response};
+/// # use libp2p_swarm::{StreamProtocol};
+/// #[derive(Debug, serde::Serialize, serde::Deserialize)]
+/// struct GreetRequest {
+///     name: String,
+/// }
+///
+/// #[derive(Debug, serde::Serialize, serde::Deserialize)]
+/// struct GreetResponse {
+///     message: String,
+/// }
+///
+/// let behaviour = json::Behaviour::<GreetRequest, GreetResponse>::new(
+///     [(StreamProtocol::new("/my-json-protocol"), ProtocolSupport::Full)],
+///     request_response::Config::default()
+/// );
+/// ```
+pub type Behaviour<Req, Resp> = crate::Behaviour<codec::Codec<Req, Resp>>;
+
+mod codec {
+    use async_trait::async_trait;
+    use futures::prelude::*;
+    use futures::{AsyncRead, AsyncWrite};
+    use libp2p_swarm::StreamProtocol;
+    use serde::{de::DeserializeOwned, Serialize};
+    use std::{io, marker::PhantomData};
+
+    /// Max request size in bytes
+    const REQUEST_SIZE_MAXIMUM: u64 = 1024 * 1024;
+    /// Max response size in bytes
+    const RESPONSE_SIZE_MAXIMUM: u64 = 10 * 1024 * 1024;
+
+    pub struct Codec<Req, Resp> {
+        phantom: PhantomData<(Req, Resp)>,
+    }
+
+    impl<Req, Resp> Default for Codec<Req, Resp> {
+        fn default() -> Self {
+            Codec {
+                phantom: PhantomData,
+            }
+        }
+    }
+
+    impl<Req, Resp> Clone for Codec<Req, Resp> {
+        fn clone(&self) -> Self {
+            Self::default()
+        }
+    }
+
+    #[async_trait]
+    impl<Req, Resp> crate::Codec for Codec<Req, Resp>
+    where
+        Req: Send + Serialize + DeserializeOwned,
+        Resp: Send + Serialize + DeserializeOwned,
+    {
+        type Protocol = StreamProtocol;
+        type Request = Req;
+        type Response = Resp;
+
+        async fn read_request<T>(&mut self, _: &Self::Protocol, io: &mut T) -> io::Result<Req>
+        where
+            T: AsyncRead + Unpin + Send,
+        {
+            let mut vec = Vec::new();
+
+            io.take(REQUEST_SIZE_MAXIMUM).read_to_end(&mut vec).await?;
+
+            Ok(serde_json::from_slice(vec.as_slice())?)
+        }
+
+        async fn read_response<T>(&mut self, _: &Self::Protocol, io: &mut T) -> io::Result<Resp>
+        where
+            T: AsyncRead + Unpin + Send,
+        {
+            let mut vec = Vec::new();
+
+            io.take(RESPONSE_SIZE_MAXIMUM).read_to_end(&mut vec).await?;
+
+            Ok(serde_json::from_slice(vec.as_slice())?)
+        }
+
+        async fn write_request<T>(
+            &mut self,
+            _: &Self::Protocol,
+            io: &mut T,
+            req: Self::Request,
+        ) -> io::Result<()>
+        where
+            T: AsyncWrite + Unpin + Send,
+        {
+            let data = serde_json::to_vec(&req)?;
+
+            io.write_all(data.as_ref()).await?;
+
+            Ok(())
+        }
+
+        async fn write_response<T>(
+            &mut self,
+            _: &Self::Protocol,
+            io: &mut T,
+            resp: Self::Response,
+        ) -> io::Result<()>
+        where
+            T: AsyncWrite + Unpin + Send,
+        {
+            let data = serde_json::to_vec(&resp)?;
+
+            io.write_all(data.as_ref()).await?;
+
+            Ok(())
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::Codec;
+    use futures::AsyncWriteExt;
+    use futures_ringbuf::Endpoint;
+    use libp2p_swarm::StreamProtocol;
+    use serde::{Deserialize, Serialize};
+
+    #[async_std::test]
+    async fn test_codec() {
+        let expected_request = TestRequest {
+            payload: "test_payload".to_string(),
+        };
+        let expected_response = TestResponse {
+            payload: "test_payload".to_string(),
+        };
+        let protocol = StreamProtocol::new("/test_json/1");
+        let mut codec: super::codec::Codec<TestRequest, TestResponse> =
+            super::codec::Codec::default();
+
+        let (mut a, mut b) = Endpoint::pair(124, 124);
+        codec
+            .write_request(&protocol, &mut a, expected_request.clone())
+            .await
+            .expect("Should write request");
+        a.close().await.unwrap();
+
+        let actual_request = codec
+            .read_request(&protocol, &mut b)
+            .await
+            .expect("Should read request");
+        b.close().await.unwrap();
+
+        assert_eq!(actual_request, expected_request);
+
+        let (mut a, mut b) = Endpoint::pair(124, 124);
+        codec
+            .write_response(&protocol, &mut a, expected_response.clone())
+            .await
+            .expect("Should write response");
+        a.close().await.unwrap();
+
+        let actual_response = codec
+            .read_response(&protocol, &mut b)
+            .await
+            .expect("Should read response");
+        b.close().await.unwrap();
+
+        assert_eq!(actual_response, expected_response);
+    }
+
+    #[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+    struct TestRequest {
+        payload: String,
+    }
+
+    #[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+    struct TestResponse {
+        payload: String,
+    }
+}