karyons jsonrpc implementation

12 files changed, 820 insertions, 0 deletions

diff --git a/Cargo.toml b/Cargo.toml
index aa5ba29..4d85f3f 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -3,6 +3,7 @@ members = [
     "core",
     "net",
     "p2p",
+    "jsonrpc",
 ]
 
 resolver = "2"
@@ -15,3 +16,4 @@ edition = "2021"
 karyons_core = { path = "core" }
 karyons_net = { path = "net" }
 karyons_p2p = { path = "p2p" }
+karyons_jsonrpc = { path = "jsonrpc" }
diff --git a/jsonrpc/Cargo.toml b/jsonrpc/Cargo.toml
new file mode 100644
index 0000000..12bea1a
--- /dev/null
+++ b/jsonrpc/Cargo.toml
@@ -0,0 +1,27 @@
+[package]
+name = "karyons_jsonrpc"
+version.workspace = true 
+edition.workspace = true
+
+[dependencies]
+karyons_core.workspace = true
+karyons_net.workspace = true
+
+smol = "1.3.0"
+log = "0.4.20"
+rand = "0.8.5"
+serde = { version = "1.0.192", features = ["derive"] }
+serde_json = "1.0.108"
+thiserror = "1.0.50"
+memchr = "2.6.4"
+
+[[example]]
+name = "server"
+path = "examples/server.rs"
+
+[[example]]
+name = "client"
+path = "examples/client.rs"
+
+[dev-dependencies]
+env_logger = "0.10.0"
diff --git a/jsonrpc/README.md b/jsonrpc/README.md
new file mode 100644
index 0000000..82ab2e9
--- /dev/null
+++ b/jsonrpc/README.md
@@ -0,0 +1,50 @@
+# karyons jsonrpc
+
+A fast and lightweight async [JSONRPC2.0](https://www.jsonrpc.org/specification) implementation.
+
+## Example
+
+```rust
+use std::sync::Arc;
+
+use serde_json::Value;
+
+use karyons_jsonrpc::{JsonRPCError, Server, Client, register_service};
+
+struct HelloWorld {}
+
+impl HelloWorld {
+    async fn say_hello(&self, params: Value) -> Result<Value, JsonRPCError> {
+        let msg: String = serde_json::from_value(params)?;
+        Ok(serde_json::json!(format!("Hello {msg}!")))
+    }
+}
+
+//////////////////
+// Server
+//////////////////
+let ex = Arc::new(smol::Executor::new());
+
+// Creates a new server
+let endpoint = "tcp://127.0.0.1:60000".parse().unwrap();
+let server = Server::new_with_endpoint(&endpoint, ex.clone()).await.unwrap();
+
+// Register the HelloWorld service
+register_service!(HelloWorld, say_hello);
+server.attach_service(HelloWorld{});
+
+// Starts the server
+ex.run(server.start());
+
+
+//////////////////
+// Client
+//////////////////
+
+// Creates a new client
+let endpoint = "tcp://127.0.0.1:60000".parse().unwrap();
+let client = Client::new_with_endpoint(&endpoint, None).await.unwrap();
+
+let result: String = client.call("HelloWorld.say_hello", "world".to_string()).await.unwrap();
+
+```
diff --git a/jsonrpc/examples/client.py b/jsonrpc/examples/client.py
new file mode 100644
index 0000000..14b3cf9
--- /dev/null
+++ b/jsonrpc/examples/client.py
@@ -0,0 +1,59 @@
+import socket
+import random
+import json
+
+HOST = "127.0.0.1"
+PORT = 60000
+
+s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+s.connect((HOST, PORT))
+
+req = {
+    "jsonrpc": "2.0",
+    "id": str(random.randint(0, 1000)),
+    "method": "Calc.add",
+    "params": {"x": 4, "y": 3},
+}
+print("Send: ", req)
+s.sendall(json.dumps(req).encode())
+res = s.recv(1024)
+res = json.loads(res)
+print("Received: ", res)
+
+req = {
+    "jsonrpc": "2.0",
+    "id": str(random.randint(0, 1000)),
+    "method": "Calc.sub",
+    "params": {"x": 4, "y": 3},
+}
+print("Send: ", req)
+s.sendall(json.dumps(req).encode())
+res = s.recv(1024)
+res = json.loads(res)
+print("Received: ", res)
+
+req = {
+    "jsonrpc": "2.0",
+    "id": str(random.randint(0, 1000)),
+    "method": "Calc.ping",
+    "params": None,
+}
+print("Send: ", req)
+s.sendall(json.dumps(req).encode())
+res = s.recv(1024)
+res = json.loads(res)
+print("Received: ", res)
+
+req = {
+    "jsonrpc": "2.0",
+    "id": str(random.randint(0, 1000)),
+    "method": "Calc.version",
+    "params": None,
+}
+print("Send: ", req)
+s.sendall(json.dumps(req).encode())
+res = s.recv(1024)
+res = json.loads(res)
+print("Received: ", res)
+
+s.close()
diff --git a/jsonrpc/examples/client.rs b/jsonrpc/examples/client.rs
new file mode 100644
index 0000000..0063098
--- /dev/null
+++ b/jsonrpc/examples/client.rs
@@ -0,0 +1,34 @@
+use serde::{Deserialize, Serialize};
+
+use karyons_jsonrpc::Client;
+
+#[derive(Deserialize, Serialize)]
+struct Req {
+    x: u32,
+    y: u32,
+}
+
+#[derive(Deserialize, Serialize, Debug)]
+struct Pong {}
+
+fn main() {
+    env_logger::init();
+    smol::future::block_on(async {
+        let endpoint = "tcp://127.0.0.1:60000".parse().unwrap();
+        let client = Client::new_with_endpoint(&endpoint, None).await.unwrap();
+
+        let params = Req { x: 10, y: 7 };
+        let result: u32 = client.call("Calc.add", params).await.unwrap();
+        println!("result {result}");
+
+        let params = Req { x: 10, y: 7 };
+        let result: u32 = client.call("Calc.sub", params).await.unwrap();
+        println!("result {result}");
+
+        let result: Pong = client.call("Calc.ping", ()).await.unwrap();
+        println!("result {:?}", result);
+
+        let result: String = client.call("Calc.version", ()).await.unwrap();
+        println!("result {result}");
+    });
+}
diff --git a/jsonrpc/examples/server.rs b/jsonrpc/examples/server.rs
new file mode 100644
index 0000000..367bfe9
--- /dev/null
+++ b/jsonrpc/examples/server.rs
@@ -0,0 +1,59 @@
+use std::sync::Arc;
+
+use serde::{Deserialize, Serialize};
+use serde_json::Value;
+
+use karyons_jsonrpc::{register_service, JsonRPCError, Server};
+
+struct Calc {
+    version: String,
+}
+
+#[derive(Deserialize, Serialize)]
+struct Req {
+    x: u32,
+    y: u32,
+}
+
+#[derive(Deserialize, Serialize)]
+struct Pong {}
+
+impl Calc {
+    async fn ping(&self, _params: Value) -> Result<Value, JsonRPCError> {
+        Ok(serde_json::json!(Pong {}))
+    }
+
+    async fn add(&self, params: Value) -> Result<Value, JsonRPCError> {
+        let params: Req = serde_json::from_value(params)?;
+        Ok(serde_json::json!(params.x + params.y))
+    }
+
+    async fn sub(&self, params: Value) -> Result<Value, JsonRPCError> {
+        let params: Req = serde_json::from_value(params)?;
+        Ok(serde_json::json!(params.x - params.y))
+    }
+
+    async fn version(&self, _params: Value) -> Result<Value, JsonRPCError> {
+        Ok(serde_json::json!(self.version))
+    }
+}
+
+fn main() {
+    env_logger::init();
+    let ex = Arc::new(smol::Executor::new());
+    smol::block_on(ex.clone().run(async {
+        // Creates a new server
+        let endpoint = "tcp://127.0.0.1:60000".parse().unwrap();
+        let server = Server::new_with_endpoint(&endpoint, ex).await.unwrap();
+
+        // Register the Calc service
+        register_service!(Calc, ping, add, sub, version);
+        let calc = Calc {
+            version: String::from("0.1"),
+        };
+        server.attach_service(calc).await;
+
+        // Start the server
+        server.start().await.unwrap();
+    }));
+}
diff --git a/jsonrpc/src/client.rs b/jsonrpc/src/client.rs
new file mode 100644
index 0000000..2863204
--- /dev/null
+++ b/jsonrpc/src/client.rs
@@ -0,0 +1,77 @@
+use log::debug;
+use serde::{de::DeserializeOwned, Serialize};
+
+use karyons_core::{async_utils::timeout, utils::random_32};
+use karyons_net::{dial, Conn, Endpoint};
+
+use crate::{
+    message,
+    utils::{read_until, write_all},
+    Error, Result, JSONRPC_VERSION,
+};
+
+/// Represents an RPC client
+pub struct Client {
+    conn: Conn,
+    timeout: Option<u64>,
+}
+
+impl Client {
+    /// Creates a new RPC client.
+    pub fn new(conn: Conn, timeout: Option<u64>) -> Self {
+        Self { conn, timeout }
+    }
+
+    /// Creates a new RPC client using the provided endpoint.
+    pub async fn new_with_endpoint(endpoint: &Endpoint, timeout: Option<u64>) -> Result<Self> {
+        let conn = dial(endpoint).await?;
+        Ok(Self { conn, timeout })
+    }
+
+    /// Calls the named method, waits for the response, and returns the result.
+    pub async fn call<T: Serialize + DeserializeOwned, V: DeserializeOwned>(
+        &self,
+        method: &str,
+        params: T,
+    ) -> Result<V> {
+        let id = serde_json::json!(random_32());
+
+        let request = message::Request {
+            jsonrpc: JSONRPC_VERSION.to_string(),
+            id,
+            method: method.to_string(),
+            params: serde_json::json!(params),
+        };
+
+        let payload = serde_json::to_vec(&request)?;
+        write_all(&self.conn, &payload).await?;
+        debug!("--> {request}");
+
+        let mut buffer = vec![];
+        if let Some(t) = self.timeout {
+            timeout(
+                std::time::Duration::from_secs(t),
+                read_until(&self.conn, &mut buffer),
+            )
+            .await?
+        } else {
+            read_until(&self.conn, &mut buffer).await
+        }?;
+
+        let response = serde_json::from_slice::<message::Response>(&buffer)?;
+        debug!("<-- {response}");
+
+        if let Some(error) = response.error {
+            return Err(Error::CallError(error.code, error.message));
+        }
+
+        if response.id.is_none() || response.id.unwrap() != request.id {
+            return Err(Error::InvalidMsg("Invalid response id"));
+        }
+
+        match response.result {
+            Some(result) => Ok(serde_json::from_value::<V>(result)?),
+            None => Err(Error::InvalidMsg("Invalid response result")),
+        }
+    }
+}
diff --git a/jsonrpc/src/error.rs b/jsonrpc/src/error.rs
new file mode 100644
index 0000000..5437c6d
--- /dev/null
+++ b/jsonrpc/src/error.rs
@@ -0,0 +1,34 @@
+use thiserror::Error as ThisError;
+
+pub type Result<T> = std::result::Result<T, Error>;
+
+/// Represents karyons's jsonrpc Error.
+#[derive(ThisError, Debug)]
+pub enum Error {
+    #[error(transparent)]
+    IO(#[from] std::io::Error),
+
+    #[error("Call Error: code: {0} msg: {1}")]
+    CallError(i32, String),
+
+    #[error("RPC Method Error:  code: {0} msg: {1}")]
+    RPCMethodError(i32, &'static str),
+
+    #[error("Invalid Params: {0}")]
+    InvalidParams(&'static str),
+
+    #[error("Invalid Request: {0}")]
+    InvalidRequest(&'static str),
+
+    #[error(transparent)]
+    ParseJSON(#[from] serde_json::Error),
+
+    #[error("Invalid Message Error: {0}")]
+    InvalidMsg(&'static str),
+
+    #[error(transparent)]
+    KaryonsCore(#[from] karyons_core::error::Error),
+
+    #[error(transparent)]
+    KaryonsNet(#[from] karyons_net::NetError),
+}
diff --git a/jsonrpc/src/lib.rs b/jsonrpc/src/lib.rs
new file mode 100644
index 0000000..8a547d9
--- /dev/null
+++ b/jsonrpc/src/lib.rs
@@ -0,0 +1,61 @@
+//! A fast and lightweight async [JSONRPC 2.0](https://www.jsonrpc.org/specification) implementation.
+//!
+//! # Example
+//!
+//! ```
+//! use std::sync::Arc;
+//!
+//! use serde_json::Value;
+//!
+//! use karyons_jsonrpc::{JsonRPCError, Server, Client, register_service};
+//!
+//! struct HelloWorld {}
+//!
+//! impl HelloWorld {
+//!     async fn say_hello(&self, params: Value) -> Result<Value, JsonRPCError> {
+//!         let msg: String = serde_json::from_value(params)?;
+//!         Ok(serde_json::json!(format!("Hello {msg}!")))
+//!     }
+//! }
+//!
+//! // Server
+//! async {
+//!     let ex = Arc::new(smol::Executor::new());
+//!
+//!     // Creates a new server
+//!     let endpoint = "tcp://127.0.0.1:60000".parse().unwrap();
+//!     let server = Server::new_with_endpoint(&endpoint, ex.clone()).await.unwrap();
+//!
+//!     // Register the HelloWorld service
+//!     register_service!(HelloWorld, say_hello);
+//!     server.attach_service(HelloWorld{});
+//!
+//!     // Starts the server
+//!     ex.run(server.start());
+//! };
+//!
+//! // Client
+//! async {
+//!
+//!     // Creates a new client
+//!     let endpoint = "tcp://127.0.0.1:60000".parse().unwrap();
+//!     let client = Client::new_with_endpoint(&endpoint, None).await.unwrap();
+//!
+//!     let result: String = client.call("HelloWorld.say_hello", "world".to_string()).await.unwrap();
+//! };
+//!
+//! ```
+
+mod client;
+mod error;
+pub mod message;
+mod server;
+mod utils;
+
+pub const JSONRPC_VERSION: &str = "2.0";
+
+use error::{Error, Result};
+
+pub use client::Client;
+pub use error::Error as JsonRPCError;
+pub use server::{RPCMethod, RPCService, Server};
diff --git a/jsonrpc/src/message.rs b/jsonrpc/src/message.rs
new file mode 100644
index 0000000..89ef613
--- /dev/null
+++ b/jsonrpc/src/message.rs
@@ -0,0 +1,91 @@
+use serde::{Deserialize, Serialize};
+
+/// Parse error: Invalid JSON was received by the server.
+pub const PARSE_ERROR_CODE: i32 = -32700;
+
+/// Invalid request: The JSON sent is not a valid Request object.
+pub const INVALID_REQUEST_ERROR_CODE: i32 = -32600;
+
+/// Method not found: The method does not exist / is not available.
+pub const METHOD_NOT_FOUND_ERROR_CODE: i32 = -32601;
+
+/// Invalid params: Invalid method parameter(s).
+pub const INVALID_PARAMS_ERROR_CODE: i32 = -32602;
+
+/// Internal error: Internal JSON-RPC error.
+pub const INTERNAL_ERROR_CODE: i32 = -32603;
+
+#[derive(Debug, Serialize, Deserialize)]
+pub struct Request {
+    pub jsonrpc: String,
+    pub method: String,
+    pub params: serde_json::Value,
+    pub id: serde_json::Value,
+}
+
+#[derive(Debug, Serialize, Deserialize)]
+pub struct Response {
+    pub jsonrpc: String,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub result: Option<serde_json::Value>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub error: Option<Error>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub id: Option<serde_json::Value>,
+}
+
+#[derive(Debug, Serialize, Deserialize)]
+pub struct Error {
+    pub code: i32,
+    pub message: String,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub data: Option<serde_json::Value>,
+}
+
+#[derive(Debug, Serialize, Deserialize)]
+pub struct Notification {
+    pub jsonrpc: String,
+    pub method: String,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub params: Option<serde_json::Value>,
+}
+
+impl std::fmt::Display for Request {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(
+            f,
+            "{{jsonrpc: {}, method: {}, params: {:?}, id: {:?}}}",
+            self.jsonrpc, self.method, self.params, self.id
+        )
+    }
+}
+
+impl std::fmt::Display for Response {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(
+            f,
+            "{{jsonrpc: {}, result': {:?}, error: {:?} , id: {:?}}}",
+            self.jsonrpc, self.result, self.error, self.id
+        )
+    }
+}
+
+impl std::fmt::Display for Error {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(
+            f,
+            "RpcError {{ code: {}, message: {}, data: {:?} }} ",
+            self.code, self.message, self.data
+        )
+    }
+}
+
+impl std::fmt::Display for Notification {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(
+            f,
+            "{{jsonrpc: {}, method: {}, params: {:?}}}",
+            self.jsonrpc, self.method, self.params
+        )
+    }
+}
diff --git a/jsonrpc/src/server.rs b/jsonrpc/src/server.rs
new file mode 100644
index 0000000..9642381
--- /dev/null
+++ b/jsonrpc/src/server.rs
@@ -0,0 +1,263 @@
+use std::{collections::HashMap, future::Future, pin::Pin, sync::Arc};
+
+use log::{debug, error, warn};
+use smol::lock::RwLock;
+
+use karyons_core::{
+    async_utils::{TaskGroup, TaskResult},
+    Executor,
+};
+use karyons_net::{listen, Conn, Endpoint, Listener};
+
+use crate::{
+    message,
+    utils::{read_until, write_all},
+    Error, Result, JSONRPC_VERSION,
+};
+
+/// Represents an RPC server
+pub struct Server<'a> {
+    listener: Box<dyn Listener>,
+    services: RwLock<HashMap<String, Box<dyn RPCService + 'a>>>,
+    task_group: TaskGroup<'a>,
+}
+
+impl<'a> Server<'a> {
+    /// Creates a new RPC server.
+    pub fn new(listener: Box<dyn Listener>, ex: Executor<'a>) -> Arc<Self> {
+        Arc::new(Self {
+            listener,
+            services: RwLock::new(HashMap::new()),
+            task_group: TaskGroup::new(ex),
+        })
+    }
+
+    /// Creates a new RPC server using the provided endpoint.
+    pub async fn new_with_endpoint(endpoint: &Endpoint, ex: Executor<'a>) -> Result<Arc<Self>> {
+        let listener = listen(endpoint).await?;
+        Ok(Arc::new(Self {
+            listener,
+            services: RwLock::new(HashMap::new()),
+            task_group: TaskGroup::new(ex),
+        }))
+    }
+
+    /// Starts the RPC server
+    pub async fn start(self: Arc<Self>) -> Result<()> {
+        loop {
+            let conn = self.listener.accept().await?;
+            self.handle_conn(conn).await?;
+        }
+    }
+
+    /// Attach a new service to the RPC server
+    pub async fn attach_service(&self, service: impl RPCService + 'a) {
+        self.services
+            .write()
+            .await
+            .insert(service.name(), Box::new(service));
+    }
+
+    /// Shuts down the RPC server
+    pub async fn shutdown(&self) {
+        self.task_group.cancel().await;
+    }
+
+    /// Handles a new connection
+    async fn handle_conn(self: &Arc<Self>, conn: Conn) -> Result<()> {
+        let endpoint = conn.peer_endpoint()?;
+        debug!("Handle a new connection {endpoint}");
+
+        let on_failure = |result: TaskResult<Result<()>>| async move {
+            if let TaskResult::Completed(Err(err)) = result {
+                error!("Connection {} dropped: {}", endpoint, err);
+            } else {
+                warn!("Connection {} dropped", endpoint);
+            }
+        };
+
+        let selfc = self.clone();
+        self.task_group.spawn(
+            async move {
+                loop {
+                    let mut buffer = vec![];
+                    read_until(&conn, &mut buffer).await?;
+                    let response = selfc.handle_request(&buffer).await;
+                    let payload = serde_json::to_vec(&response)?;
+                    write_all(&conn, &payload).await?;
+                    debug!("--> {response}");
+                }
+            },
+            on_failure,
+        );
+
+        Ok(())
+    }
+
+    /// Handles a request
+    async fn handle_request(&self, buffer: &[u8]) -> message::Response {
+        let rpc_msg = match serde_json::from_slice::<message::Request>(buffer) {
+            Ok(m) => m,
+            Err(_) => {
+                return self.pack_err_res(message::PARSE_ERROR_CODE, "Failed to parse", None);
+            }
+        };
+
+        debug!("<-- {rpc_msg}");
+
+        let srvc_method: Vec<&str> = rpc_msg.method.split('.').collect();
+        if srvc_method.len() != 2 {
+            return self.pack_err_res(
+                message::INVALID_REQUEST_ERROR_CODE,
+                "Invalid request",
+                Some(rpc_msg.id),
+            );
+        }
+
+        let srvc_name = srvc_method[0];
+        let method_name = srvc_method[1];
+
+        let services = self.services.read().await;
+
+        let service = match services.get(srvc_name) {
+            Some(s) => s,
+            None => {
+                return self.pack_err_res(
+                    message::METHOD_NOT_FOUND_ERROR_CODE,
+                    "Method not found",
+                    Some(rpc_msg.id),
+                );
+            }
+        };
+
+        let method = match service.get_method(method_name) {
+            Some(m) => m,
+            None => {
+                return self.pack_err_res(
+                    message::METHOD_NOT_FOUND_ERROR_CODE,
+                    "Method not found",
+                    Some(rpc_msg.id),
+                );
+            }
+        };
+
+        let result = match method(rpc_msg.params.clone()).await {
+            Ok(res) => res,
+            Err(Error::ParseJSON(_)) => {
+                return self.pack_err_res(
+                    message::PARSE_ERROR_CODE,
+                    "Failed to parse",
+                    Some(rpc_msg.id),
+                );
+            }
+            Err(Error::InvalidParams(msg)) => {
+                return self.pack_err_res(
+                    message::INVALID_PARAMS_ERROR_CODE,
+                    msg,
+                    Some(rpc_msg.id),
+                );
+            }
+            Err(Error::InvalidRequest(msg)) => {
+                return self.pack_err_res(
+                    message::INVALID_REQUEST_ERROR_CODE,
+                    msg,
+                    Some(rpc_msg.id),
+                );
+            }
+            Err(Error::RPCMethodError(code, msg)) => {
+                return self.pack_err_res(code, msg, Some(rpc_msg.id));
+            }
+            Err(_) => {
+                return self.pack_err_res(
+                    message::INTERNAL_ERROR_CODE,
+                    "Internal error",
+                    Some(rpc_msg.id),
+                );
+            }
+        };
+
+        message::Response {
+            jsonrpc: JSONRPC_VERSION.to_string(),
+            error: None,
+            result: Some(result),
+            id: Some(rpc_msg.id),
+        }
+    }
+
+    fn pack_err_res(
+        &self,
+        code: i32,
+        msg: &str,
+        id: Option<serde_json::Value>,
+    ) -> message::Response {
+        let err = message::Error {
+            code,
+            message: msg.to_string(),
+            data: None,
+        };
+
+        message::Response {
+            jsonrpc: JSONRPC_VERSION.to_string(),
+            error: Some(err),
+            result: None,
+            id,
+        }
+    }
+}
+
+/// Represents the RPC method
+pub type RPCMethod<'a> = Box<dyn Fn(serde_json::Value) -> RPCMethodOutput<'a> + Send + 'a>;
+type RPCMethodOutput<'a> =
+    Pin<Box<dyn Future<Output = Result<serde_json::Value>> + Send + Sync + 'a>>;
+
+/// Defines the interface for an RPC service.
+pub trait RPCService: Sync + Send {
+    fn get_method<'a>(&'a self, name: &'a str) -> Option<RPCMethod>;
+    fn name(&self) -> String;
+}
+
+/// Implements the `RPCService` trait for a provided type.
+///
+/// # Example
+///
+/// ```
+/// use serde_json::Value;
+///
+/// use karyons_jsonrpc::{JsonRPCError, register_service};
+///
+/// struct Hello {}
+///
+/// impl Hello {
+///     async fn say_hello(&self, params: Value) -> Result<Value, JsonRPCError> {
+///         Ok(serde_json::json!("hello!"))
+///     }
+/// }
+///
+/// register_service!(Hello, say_hello);
+///
+/// ```
+#[macro_export]
+macro_rules! register_service {
+    ($t:ty, $($m:ident),*) => {
+        impl karyons_jsonrpc::RPCService for $t {
+            fn get_method<'a>(
+                &'a self,
+                name: &'a str
+            ) -> Option<karyons_jsonrpc::RPCMethod> {
+                match name {
+                $(
+                    stringify!($m) => {
+                        Some(Box::new(move |params: serde_json::Value| Box::pin(self.$m(params))))
+                    }
+                )*
+                    _ => None,
+                }
+
+
+            }
+            fn name(&self) -> String{
+                stringify!($t).to_string()
+            }
+        }
+    };
+}
diff --git a/jsonrpc/src/utils.rs b/jsonrpc/src/utils.rs
new file mode 100644
index 0000000..1f21b7a
--- /dev/null
+++ b/jsonrpc/src/utils.rs
@@ -0,0 +1,63 @@
+use memchr::memchr;
+
+use karyons_net::Conn;
+
+use crate::{Error, Result};
+
+const DEFAULT_MSG_SIZE: usize = 1024;
+const MAX_ALLOWED_MSG_SIZE: usize = 1024 * 1024; // 1MB
+
+// TODO: Add unit tests for these functions.
+
+/// Read all bytes into `buffer` until the `0x0` byte or EOF is
+/// reached.
+///
+/// If successful, this function will return the total number of bytes read.
+pub async fn read_until(conn: &Conn, buffer: &mut Vec<u8>) -> Result<usize> {
+    let delim = b'\0';
+
+    let mut read = 0;
+
+    loop {
+        let mut tmp_buf = [0; DEFAULT_MSG_SIZE];
+        let n = conn.read(&mut tmp_buf).await?;
+        if n == 0 {
+            return Err(Error::IO(std::io::ErrorKind::UnexpectedEof.into()));
+        }
+
+        match memchr(delim, &tmp_buf) {
+            Some(i) => {
+                buffer.extend_from_slice(&tmp_buf[..i]);
+                read += i;
+                break;
+            }
+            None => {
+                buffer.extend_from_slice(&tmp_buf);
+                read += tmp_buf.len();
+            }
+        }
+
+        if buffer.len() == MAX_ALLOWED_MSG_SIZE {
+            return Err(Error::InvalidMsg(
+                "Message exceeds the maximum allowed size",
+            ));
+        }
+    }
+
+    Ok(read)
+}
+
+/// Writes an entire buffer into the given connection.
+pub async fn write_all(conn: &Conn, mut buf: &[u8]) -> Result<()> {
+    while !buf.is_empty() {
+        let n = conn.write(buf).await?;
+        let (_, rest) = std::mem::take(&mut buf).split_at(n);
+        buf = rest;
+
+        if n == 0 {
+            return Err(Error::IO(std::io::ErrorKind::UnexpectedEof.into()));
+        }
+    }
+
+    Ok(())
+}