Add blocking lnd client

src/blocking_client.rs

@@ -0,0 +1,41 @@
+use std::path::PathBuf;
+use tokio::runtime::{Builder, Runtime};
+use tonic_lnd::signrpc::{KeyDescriptor, KeyLocator, SignMessageReq, SignMessageResp};
+use tonic_lnd::{connect, Client};
+
+// For some LND grpc calls, we need a blocking version of the client. Namely, in order to use LDK's "sign"
+// API for signing an invoice request, the provided closure containing the LND signing API calls can't be
+// asynchronous.
+pub(crate) struct BlockingClient {
+    client: Client,
+    rt: Runtime,
+}
+
+impl BlockingClient {
+    pub(crate) fn connect(
+        address: String,
+        cert_path: PathBuf,
+        macaroon_path: PathBuf,
+    ) -> Result<Self, tonic::transport::Error> {
+        let rt = Builder::new_multi_thread().enable_all().build().unwrap();
+        let client = rt
+            .block_on(connect(address, cert_path, macaroon_path))
+            .unwrap();
+
+        Ok(Self { client, rt })
+    }
+
+    pub(crate) fn derive_key(
+        &mut self,
+        request: KeyLocator,
+    ) -> Result<tonic_lnd::tonic::Response<KeyDescriptor>, tonic_lnd::tonic::Status> {
+        self.rt.block_on(self.client.wallet().derive_key(request))
+    }
+
+    pub(crate) fn sign_message(
+        &mut self,
+        request: SignMessageReq,
+    ) -> Result<tonic_lnd::tonic::Response<SignMessageResp>, tonic_lnd::tonic::Status> {
+        self.rt.block_on(self.client.signer().sign_message(request))
+    }
+}