From 4c34e40a4c03654f28564d39319ee8ee4aac263f Mon Sep 17 00:00:00 2001
From: Birk Tjelmeland <git@birktj.no>
Date: Mon, 26 Aug 2024 17:02:33 +0200
Subject: [PATCH] feat(types): add `lenient` feature

The `lenient` feature allows for parsing `Request`s and
`Notification`s that doesn't have `jsonrpc` fields. This is useful
for interacting with some implementations that are not completely
standards-conforming.
---
 jsonrpsee/Cargo.toml |  1 +
 jsonrpsee/src/lib.rs |  1 +
 types/Cargo.toml     |  3 +++
 types/src/request.rs | 12 ++++++++++++
 4 files changed, 17 insertions(+)

diff --git a/jsonrpsee/Cargo.toml b/jsonrpsee/Cargo.toml
index 5211011d3d..3351b7cec5 100644
--- a/jsonrpsee/Cargo.toml
+++ b/jsonrpsee/Cargo.toml
@@ -37,6 +37,7 @@ http-client = ["jsonrpsee-http-client", "jsonrpsee-types", "jsonrpsee-core/clien
 wasm-client = ["jsonrpsee-wasm-client", "jsonrpsee-types", "jsonrpsee-core/client"]
 ws-client = ["jsonrpsee-ws-client", "jsonrpsee-types", "jsonrpsee-core/client"]
 macros = ["jsonrpsee-proc-macros", "jsonrpsee-types", "tracing"]
+lenient = ["jsonrpsee-types/lenient"]
 
 client = ["http-client", "ws-client", "wasm-client", "client-ws-transport-tls", "client-web-transport", "async-client", "async-wasm-client", "client-core"]
 client-core = ["jsonrpsee-core/client"]
diff --git a/jsonrpsee/src/lib.rs b/jsonrpsee/src/lib.rs
index 3df36e5c8f..b485d6be26 100644
--- a/jsonrpsee/src/lib.rs
+++ b/jsonrpsee/src/lib.rs
@@ -48,6 +48,7 @@
 //! - **`client-ws-transport`** - Enables `ws` transport with TLS.
 //! - **`client-ws-transport-no-tls`** - Enables `ws` transport without TLS.
 //! - **`client-web-transport`** - Enables `websys` transport.
+//! - **`lenient`** - Enables lenient request parsing, allowing requests without a `jsonrpc` field.
 
 #![warn(missing_docs, missing_debug_implementations, missing_copy_implementations, unreachable_pub)]
 #![cfg_attr(not(test), warn(unused_crate_dependencies))]
diff --git a/types/Cargo.toml b/types/Cargo.toml
index 62039633b2..a3de1f3edf 100644
--- a/types/Cargo.toml
+++ b/types/Cargo.toml
@@ -18,3 +18,6 @@ serde = { version = "1", default-features = false, features = ["derive"] }
 serde_json = { version = "1", default-features = false, features = ["alloc", "raw_value", "std"] }
 thiserror = "1.0"
 http = "1"
+
+[features]
+lenient = []
diff --git a/types/src/request.rs b/types/src/request.rs
index 28026a0392..262bfd300d 100644
--- a/types/src/request.rs
+++ b/types/src/request.rs
@@ -41,6 +41,7 @@ use serde_json::value::RawValue;
 #[derive(Serialize, Deserialize, Debug, Clone)]
 pub struct Request<'a> {
 	/// JSON-RPC version.
+	#[cfg_attr(feature = "lenient", serde(default))]
 	pub jsonrpc: TwoPointZero,
 	/// Request ID
 	#[serde(borrow)]
@@ -101,6 +102,7 @@ pub struct InvalidRequest<'a> {
 #[derive(Serialize, Deserialize, Debug, Clone)]
 pub struct Notification<'a, T> {
 	/// JSON-RPC version.
+	#[cfg_attr(feature = "lenient", serde(default))]
 	pub jsonrpc: TwoPointZero,
 	/// Name of the method to be invoked.
 	#[serde(borrow)]
@@ -240,6 +242,16 @@ mod test {
 		assert!(serde_json::from_str::<Request>(ser).is_err());
 	}
 
+	#[test]
+	fn deserialize_missing_jsonrpc_field() {
+		let ser = r#"{"method":"say_hello","params":[],"id":1}"#;
+		#[cfg(feature = "lenient")]
+		assert!(serde_json::from_str::<Request>(ser).is_ok());
+
+		#[cfg(not(feature = "lenient"))]
+		assert!(serde_json::from_str::<Request>(ser).is_err());
+	}
+
 	#[test]
 	fn deserialize_invalid_request() {
 		let s = r#"{"id":120,"method":"my_method","params":["foo", "bar"],"extra_field":[]}"#;