Use language agnostic heuristic to check if monero_wallet_rpc is ready

Our strategy of searching for a english string to determine if
monero_wallet_rpc is ready is not compatible with languages other than
english. Instead we assume the monero rpc is ready if it has stopped
writing to stdout. We make a json rpc request to confirm this. A better
solution would have been to configure the monero_wallet_rpc to always
output in english but there is not command line argument to configure
the language.

Closes #353.

CHANGELOG.md

@@ -11,4 +11,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - A changelog file.
 
+### Fixed
+
+- Make monero_wallet_rpc readiness check language agnostic. The readiness check was
+  failing on non-english language systems preventing users from starting the swap-cli
+  and asb.
+
 [Unreleased]: https://github.com/comit-network/xmr-btc-swap/compare/v0.3...HEAD

monero-rpc/src/rpc/wallet.rs

@@ -357,6 +357,24 @@ impl Client {
         let r = serde_json::from_str::<Response<SweepAll>>(&response)?;
         Ok(r.result)
     }
+
+    pub async fn get_version(&self) -> Result<Version> {
+        let request = Request::new("get_version", "");
+
+        let response = self
+            .inner
+            .post(self.url.clone())
+            .json(&request)
+            .send()
+            .await?
+            .text()
+            .await?;
+
+        debug!("get_version RPC response: {}", response);
+
+        let r = serde_json::from_str::<Response<Version>>(&response)?;
+        Ok(r.result)
+    }
 }
 
 #[derive(Serialize, Debug, Clone)]
@@ -512,6 +530,11 @@ pub struct SweepAll {
     weight_list: Vec<u32>,
 }
 
+#[derive(Debug, Copy, Clone, Deserialize)]
+pub struct Version {
+    version: u32,
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

swap/src/monero/wallet_rpc.rs

@@ -2,11 +2,13 @@ use ::monero::Network;
 use anyhow::{Context, Result};
 use big_bytes::BigByte;
 use futures::{StreamExt, TryStreamExt};
+use monero_rpc::wallet::Client;
 use reqwest::header::CONTENT_LENGTH;
 use reqwest::Url;
 use std::io::ErrorKind;
 use std::path::{Path, PathBuf};
 use std::process::Stdio;
+use std::time::Duration;
 use tokio::fs::{remove_file, OpenOptions};
 use tokio::io::{AsyncBufReadExt, AsyncWriteExt, BufReader};
 use tokio::process::{Child, Command};
@@ -146,12 +148,16 @@ impl WalletRpc {
 
         let mut reader = BufReader::new(stdout).lines();
 
-        while let Some(line) = reader.next_line().await? {
-            if line.contains("Starting wallet RPC server") {
-                break;
-            }
+        // If we do not hear from the monero_wallet_rpc process for 3 seconds we assume
+        // it is is ready
+        while let Ok(line) = tokio::time::timeout(Duration::from_secs(3), reader.next_line()).await
+        {
+            line?;
         }
 
+        // Send a json rpc request to make sure monero_wallet_rpc is ready
+        Client::localhost(port).get_version().await?;
+
         Ok(WalletRpcProcess {
             _child: child,
             port,