cln-rpc: Scaffolding for the cln-rpc crate

Cargo.toml

@@ -0,0 +1,4 @@
+[workspace]
+members = [
+  "cln-rpc",
+]

Makefile

@@ -355,7 +355,7 @@ ifneq ($(FUZZING),0)
 	include tests/fuzz/Makefile
 endif
 ifneq ($(RUST),0)
-# Add Rust Makefiles here
+	include cln-rpc/Makefile
 endif
 
 # We make pretty much everything depend on these.

cln-rpc/Cargo.toml

@@ -0,0 +1,19 @@
+[package]
+name = "cln-rpc"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+anyhow = "1.0.51"
+bytes = "1.1.0"
+log = "0.4.14"
+serde = { version = "1.0.131", features = ["derive"] }
+serde_json = "1.0.72"
+tokio-util = { version = "0.6.9", features = ["codec"] }
+tokio = { version = "1", features = ["net"]}
+native-tls = { version = "*", features = ["vendored"] }
+futures-util = { version = "*", features = [ "sink" ] }
+
+[dev-dependencies]
+tokio = { version = "1", features = ["net", "macros", "rt-multi-thread"]}
+env_logger = "*"

cln-rpc/Makefile

@@ -0,0 +1,16 @@
+cln-rpc-wrongdir:
+	$(MAKE) -C .. cln-rpc-all
+
+CLN_RPC_EXAMPLES :=
+CLN_RPC_GENALL = cln-rpc/src/model.rs
+CLN_RPC_SOURCES = $(shell find cln-rpc -name *.rs) ${CLN_RPC_GENALL}
+JSON_SCHEMA = doc/schemas/*.schema.json
+DEFAULT_TARGETS += $(CLN_RPC_EXAMPLES) $(CLN_RPC_GENALL)
+
+$(CLN_RPC_GENALL): $(JSON_SCHEMA)
+	PYTHONPATH=contrib/msggen python3 contrib/msggen/msggen/__main__.py
+
+target/debug/examples/cln-rpc-getinfo: $(shell find cln-rpc -name *.rs)
+	cargo build --example cln-rpc-getinfo
+
+cln-rpc-all: ${CLN_RPC_GEN_ALL} ${CLN_RPC_EXAMPLES}

cln-rpc/README.md

@@ -0,0 +1,3 @@
+# `cln-rpc`: Talk to c-lightning
+
+

cln-rpc/src/codec.rs

@@ -0,0 +1,210 @@
+//! The codec is used to encode and decode messages received from and
+//! sent to the main daemon. The protocol uses `stdout` and `stdin` to
+//! exchange JSON formatted messages. Each message is separated by an
+//! empty line and we're guaranteed that no other empty line is
+//! present in the messages.
+use crate::Error;
+use anyhow::anyhow;
+use bytes::{BufMut, BytesMut};
+use serde_json::value::Value;
+use std::str::FromStr;
+use std::{io, str};
+use tokio_util::codec::{Decoder, Encoder};
+
+pub use crate::jsonrpc::JsonRpc;
+use crate::{
+    model::{Request},
+    notifications::Notification,
+};
+
+/// A simple codec that parses messages separated by two successive
+/// `\n` newlines.
+#[derive(Default)]
+pub struct MultiLineCodec {}
+
+/// Find two consecutive newlines, i.e., an empty line, signalling the
+/// end of one message and the start of the next message.
+fn find_separator(buf: &mut BytesMut) -> Option<usize> {
+    buf.iter()
+        .zip(buf.iter().skip(1))
+        .position(|b| *b.0 == b'\n' && *b.1 == b'\n')
+}
+
+fn utf8(buf: &[u8]) -> Result<&str, io::Error> {
+    str::from_utf8(buf)
+        .map_err(|_| io::Error::new(io::ErrorKind::InvalidData, "Unable to decode input as UTF8"))
+}
+
+impl Decoder for MultiLineCodec {
+    type Item = String;
+    type Error = Error;
+    fn decode(&mut self, buf: &mut BytesMut) -> Result<Option<Self::Item>, Error> {
+        if let Some(newline_offset) = find_separator(buf) {
+            let line = buf.split_to(newline_offset + 2);
+            let line = &line[..line.len() - 2];
+            let line = utf8(line)?;
+            Ok(Some(line.to_string()))
+        } else {
+            Ok(None)
+        }
+    }
+}
+
+impl<T> Encoder<T> for MultiLineCodec
+where
+    T: AsRef<str>,
+{
+    type Error = Error;
+    fn encode(&mut self, line: T, buf: &mut BytesMut) -> Result<(), Self::Error> {
+        let line = line.as_ref();
+        buf.reserve(line.len() + 2);
+        buf.put(line.as_bytes());
+        buf.put_u8(b'\n');
+        buf.put_u8(b'\n');
+        Ok(())
+    }
+}
+
+#[derive(Default)]
+pub struct JsonCodec {
+    /// Sub-codec used to split the input into chunks that can then be
+    /// parsed by the JSON parser.
+    inner: MultiLineCodec,
+}
+
+impl<T> Encoder<T> for JsonCodec
+where
+    T: Into<Value>,
+{
+    type Error = Error;
+    fn encode(&mut self, msg: T, buf: &mut BytesMut) -> Result<(), Self::Error> {
+        let s = msg.into().to_string();
+        self.inner.encode(s, buf)
+    }
+}
+
+impl Decoder for JsonCodec {
+    type Item = Value;
+    type Error = Error;
+
+    fn decode(&mut self, buf: &mut BytesMut) -> Result<Option<Self::Item>, Error> {
+        match self.inner.decode(buf) {
+            Ok(None) => Ok(None),
+            Err(e) => Err(e),
+            Ok(Some(s)) => {
+                if let Ok(v) = Value::from_str(&s) {
+                    Ok(Some(v))
+                } else {
+                    Err(anyhow!("failed to parse JSON"))
+                }
+            }
+        }
+    }
+}
+
+/// A codec that reads fully formed [crate::messages::JsonRpc]
+/// messages. Internally it uses the [JsonCodec] which itself is built
+/// on the [MultiLineCodec].
+#[derive(Default)]
+pub(crate) struct JsonRpcCodec {
+    inner: JsonCodec,
+}
+
+impl Decoder for JsonRpcCodec {
+    type Item = JsonRpc<Notification, Request>;
+    type Error = Error;
+
+    fn decode(&mut self, buf: &mut BytesMut) -> Result<Option<Self::Item>, Error> {
+        match self.inner.decode(buf) {
+            Ok(None) => Ok(None),
+            Err(e) => Err(e),
+            Ok(Some(s)) => {
+                let req: Self::Item = serde_json::from_value(s)?;
+                Ok(Some(req))
+            }
+        }
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::{find_separator, JsonCodec, MultiLineCodec};
+    use bytes::{BufMut, BytesMut};
+    use serde_json::json;
+    use tokio_util::codec::{Decoder, Encoder};
+
+    #[test]
+    fn test_separator() {
+        struct Test(String, Option<usize>);
+        let tests = vec![
+            Test("".to_string(), None),
+            Test("}\n\n".to_string(), Some(1)),
+            Test("\"hello\"},\n\"world\"}\n\n".to_string(), Some(18)),
+        ];
+
+        for t in tests.iter() {
+            let mut buf = BytesMut::new();
+            buf.put_slice(t.0.as_bytes());
+            assert_eq!(find_separator(&mut buf), t.1);
+        }
+    }
+
+    #[test]
+    fn test_ml_decoder() {
+        struct Test(String, Option<String>, String);
+        let tests = vec![
+            Test("".to_string(), None, "".to_string()),
+            Test(
+                "{\"hello\":\"world\"}\n\nremainder".to_string(),
+                Some("{\"hello\":\"world\"}".to_string()),
+                "remainder".to_string(),
+            ),
+            Test(
+                "{\"hello\":\"world\"}\n\n{}\n\nremainder".to_string(),
+                Some("{\"hello\":\"world\"}".to_string()),
+                "{}\n\nremainder".to_string(),
+            ),
+        ];
+
+        for t in tests.iter() {
+            let mut buf = BytesMut::new();
+            buf.put_slice(t.0.as_bytes());
+
+            let mut codec = MultiLineCodec::default();
+            let mut remainder = BytesMut::new();
+            remainder.put_slice(t.2.as_bytes());
+
+            assert_eq!(codec.decode(&mut buf).unwrap(), t.1);
+            assert_eq!(buf, remainder);
+        }
+    }
+
+    #[test]
+    fn test_ml_encoder() {
+        let tests = vec!["test"];
+
+        for t in tests.iter() {
+            let mut buf = BytesMut::new();
+            let mut codec = MultiLineCodec::default();
+            let mut expected = BytesMut::new();
+            expected.put_slice(t.as_bytes());
+            expected.put_u8(b'\n');
+            expected.put_u8(b'\n');
+            codec.encode(t, &mut buf).unwrap();
+            assert_eq!(buf, expected);
+        }
+    }
+
+    #[test]
+    fn test_json_codec() {
+        let tests = vec![json!({"hello": "world"})];
+
+        for t in tests.iter() {
+            let mut codec = JsonCodec::default();
+            let mut buf = BytesMut::new();
+            codec.encode(t.clone(), &mut buf).unwrap();
+            let decoded = codec.decode(&mut buf).unwrap().unwrap();
+            assert_eq!(&decoded, t);
+        }
+    }
+}

cln-rpc/src/jsonrpc.rs

@@ -0,0 +1,88 @@
+//! Common structs to handle JSON-RPC decoding and encoding. They are
+//! generic over the Notification and Request types.
+
+use serde::ser::{SerializeStruct, Serializer};
+use serde::de::{self, Deserializer};
+use serde::{Deserialize, Serialize};
+use serde_json::Value;
+use std::fmt::Debug;
+
+#[derive(Debug)]
+pub enum JsonRpc<N, R> {
+    Request(usize, R),
+    Notification(N),
+}
+
+/// This function disentangles the various cases:
+///
+///   1) If we have an `id` then it is a request
+///
+///   2) Otherwise it's a notification that doesn't require a
+///   response.
+///
+/// Furthermore we distinguish between the built-in types and the
+/// custom user notifications/methods:
+///
+///   1) We either match a built-in type above,
+///
+///   2) Or it's a custom one, so we pass it around just as a
+///   `serde_json::Value`
+impl<'de, N, R> Deserialize<'de> for JsonRpc<N, R>
+where
+    N: Deserialize<'de> + Debug,
+    R: Deserialize<'de> + Debug,
+{
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        #[derive(Deserialize, Debug)]
+        struct IdHelper {
+            id: Option<usize>,
+        }
+
+        let v = Value::deserialize(deserializer)?;
+        let helper = IdHelper::deserialize(&v).map_err(de::Error::custom)?;
+        match helper.id {
+            Some(id) => {
+                let r = R::deserialize(v).map_err(de::Error::custom)?;
+                Ok(JsonRpc::Request(id, r))
+            }
+            None => {
+                let n = N::deserialize(v).map_err(de::Error::custom)?;
+                Ok(JsonRpc::Notification(n))
+            }
+        }
+    }
+}
+
+impl<N, R> Serialize for JsonRpc<N, R>
+where
+    N: Serialize + Debug,
+    R: Serialize + Debug,
+{
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: Serializer,
+    {
+        match self {
+            JsonRpc::Notification(r) => {
+                let r = serde_json::to_value(r).unwrap();
+                let mut s = serializer.serialize_struct("Notification", 3)?;
+                s.serialize_field("jsonrpc", "2.0")?;
+                s.serialize_field("method", &r["method"])?;
+                s.serialize_field("params", &r["params"])?;
+                s.end()
+            }
+            JsonRpc::Request(id, r) => {
+                let r = serde_json::to_value(r).unwrap();
+                let mut s = serializer.serialize_struct("Request", 4)?;
+                s.serialize_field("jsonrpc", "2.0")?;
+                s.serialize_field("id", id)?;
+                s.serialize_field("method", &r["method"])?;
+                s.serialize_field("params", &r["params"])?;
+                s.end()
+            }
+        }
+    }
+}