Add little command for easy access to JSON-RPC interface

Cargo.toml

@@ -16,6 +16,7 @@ tracing-subscriber = "0.2.18"
 trin-core = { path = "trin-core" }
 trin-history = { path = "trin-history" }
 trin-state = { path = "trin-state" }
+trin-cli = { path = "trin-cli" }
 
 [dependencies.discv5]
 version = "0.1.0-beta.10"
@@ -26,5 +27,6 @@ members = [
     "trin-history",
     "trin-state",
     "trin-core",
+    "trin-cli",
     "ethportal-peertest"
 ]

trin-cli/Cargo.toml

@@ -0,0 +1,18 @@
+[package]
+name = "trin-cli"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+structopt="0.3.25"
+trin-core = { path = "../trin-core" }
+jsonrpc = "0.12.0"
+serde_json = "1.0.68"
+serde = "1.0.117"
+thiserror = "1.0.29"
+
+[[bin]]
+name="trin-cli"
+path="src/main.rs"

trin-cli/src/main.rs

@@ -0,0 +1,125 @@
+use std::os::unix::net::UnixStream;
+use std::path::{Path, PathBuf};
+use structopt::StructOpt;
+use thiserror::Error;
+
+use trin_core::cli::DEFAULT_WEB3_IPC_PATH;
+
+#[derive(StructOpt, Debug)]
+#[structopt(
+    name = "trin-cli",
+    version = "0.0.1",
+    author = "Ethereum Foundation",
+    about = "Run JSON-RPC commands against trin nodes"
+)]
+struct Config {
+    #[structopt(
+        default_value(DEFAULT_WEB3_IPC_PATH),
+        long,
+        help = "path to JSON-RPC endpoint"
+    )]
+    ipc: PathBuf,
+
+    #[structopt(help = "e.g. discv5_routingTableInfo", required = true)]
+    endpoint: String,
+}
+
+fn main() -> Result<(), Box<dyn std::error::Error>> {
+    let Config { ipc, endpoint } = Config::from_args();
+
+    eprintln!(
+        "Attempting RPC. endpoint={} file={}",
+        endpoint,
+        ipc.to_string_lossy()
+    );
+    let mut client = TrinClient::from_ipc(&ipc)?;
+
+    let req = client.build_request(endpoint.as_str());
+    let resp = client.make_request(req)?;
+
+    println!("{}", serde_json::to_string_pretty(&resp).unwrap());
+    Ok(())
+}
+
+fn build_request(method: &str, request_id: u64) -> jsonrpc::Request {
+    jsonrpc::Request {
+        method,
+        params: &[],
+        id: serde_json::json!(request_id),
+        jsonrpc: Some("2.0"),
+    }
+}
+
+pub trait TryClone {
+    fn try_clone(&self) -> std::io::Result<Self>
+    where
+        Self: Sized;
+}
+
+impl TryClone for UnixStream {
+    fn try_clone(&self) -> std::io::Result<Self> {
+        UnixStream::try_clone(self)
+    }
+}
+
+pub struct TrinClient<S>
+where
+    S: std::io::Read + std::io::Write + TryClone,
+{
+    stream: S,
+    request_id: u64,
+}
+
+impl TrinClient<UnixStream> {
+    fn from_ipc(path: &Path) -> std::io::Result<Self> {
+        // TODO: a nice error if this file does not exist
+        Ok(Self {
+            stream: UnixStream::connect(path)?,
+            request_id: 0,
+        })
+    }
+}
+
+#[derive(Error, Debug)]
+pub enum JsonRpcError {
+    #[error("Received malformed response: {0}")]
+    Malformed(serde_json::Error),
+
+    #[error("Received empty response")]
+    Empty,
+}
+
+// TryClone is used because JSON-RPC responses are not followed by EOF. We must read bytes
+// from the stream until a complete object is detected, and the simplest way of doing that
+// with available APIs is to give ownership of a Read to a serde_json::Deserializer. If we
+// gave it exclusive ownership that would require us to open a new connection for every
+// command we wanted to send! By making a clone (or, by trying to) we can have our cake
+// and eat it too.
+impl<'a, S> TrinClient<S>
+where
+    S: std::io::Read + std::io::Write + TryClone,
+{
+    fn build_request(&mut self, method: &'a str) -> jsonrpc::Request<'a> {
+        let result = build_request(method, self.request_id);
+        self.request_id += 1;
+
+        result
+    }
+
+    fn make_request(&mut self, req: jsonrpc::Request) -> Result<serde_json::Value, JsonRpcError> {
+        let data = serde_json::to_vec(&req).unwrap();
+
+        self.stream.write_all(&data).unwrap();
+        self.stream.flush().unwrap();
+
+        let clone = self.stream.try_clone().unwrap();
+        let deser = serde_json::Deserializer::from_reader(clone);
+
+        if let Some(obj) = deser.into_iter::<serde_json::Value>().next() {
+            return obj.map_err(JsonRpcError::Malformed);
+        }
+
+        // this should only happen when they immediately send EOF
+        Err(JsonRpcError::Empty)
+    }
+}