From b25ea51a15d826a1a50f004e09c071c57c9fd9be Mon Sep 17 00:00:00 2001
From: Dominik Nakamura <dnaka91@gmail.com>
Date: Thu, 11 Mar 2021 20:59:32 +0900
Subject: [PATCH] Check OBS and plugin version after connecting

---
 src/client/mod.rs | 56 +++++++++++++++++++++++++++++++++++++++++++++--
 src/lib.rs        | 11 +++++++++-
 2 files changed, 64 insertions(+), 3 deletions(-)

diff --git a/src/client/mod.rs b/src/client/mod.rs
index 3e1e9af..b640cd5 100644
--- a/src/client/mod.rs
+++ b/src/client/mod.rs
@@ -18,6 +18,7 @@ use futures_util::{
     stream::{SplitSink, StreamExt},
 };
 use log::{debug, error, trace};
+use semver::VersionReq;
 use serde::de::DeserializeOwned;
 #[cfg(feature = "events")]
 use tokio::sync::broadcast;
@@ -118,6 +119,9 @@ where
     pub broadcast_capacity: Option<usize>,
 }
 
+const OBS_STUDIO_VERSION: &str = "^26.1.2";
+const OBS_WEBSOCKET_VERSION: &str = "~4.9.0";
+
 impl<H> ConnectConfig<H>
 where
     H: AsRef<str>,
@@ -227,14 +231,42 @@ impl Client {
         let write = Mutex::new(write);
         let id_counter = AtomicU64::new(1);
 
-        Ok(Self {
+        let client = Self {
             write,
             id_counter,
             receivers,
             #[cfg(feature = "events")]
             event_sender: Arc::downgrade(&event_sender),
             handle: Some(handle),
-        })
+        };
+
+        client.verify_versions().await?;
+
+        Ok(client)
+    }
+
+    async fn verify_versions(&self) -> Result<()> {
+        let version = self.general().get_version().await?;
+        // These are guaranteed to succeed and covered by tests. Therefore, it's safe to unwrap.
+        // Unfortunately there is (currently) no "safe" way to create version req.
+        let obs_studio = VersionReq::parse(OBS_STUDIO_VERSION).unwrap();
+        let obs_websocket = VersionReq::parse(OBS_WEBSOCKET_VERSION).unwrap();
+
+        if !obs_studio.matches(&version.obs_studio_version) {
+            return Err(Error::ObsStudioVersion(
+                version.obs_studio_version,
+                obs_studio,
+            ));
+        }
+
+        if !obs_websocket.matches(&version.obs_websocket_version) {
+            return Err(Error::ObsWebsocketVersion(
+                version.obs_websocket_version,
+                obs_websocket,
+            ));
+        }
+
+        Ok(())
     }
 
     async fn send_message<T>(&self, req: RequestType<'_>) -> Result<T>
@@ -442,3 +474,23 @@ impl Drop for Client {
         drop(self.disconnect());
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use semver::Version;
+
+    use super::*;
+
+    #[test]
+    fn verify_version_req() {
+        let obs_studio = VersionReq::parse(OBS_STUDIO_VERSION).unwrap();
+        assert!(obs_studio.matches(&Version::parse("26.1.100").unwrap()));
+        assert!(obs_studio.matches(&Version::parse("26.100.100").unwrap()));
+        assert!(!obs_studio.matches(&Version::parse("27.0.0").unwrap()));
+
+        let obs_websocket = VersionReq::parse(OBS_WEBSOCKET_VERSION).unwrap();
+        assert!(obs_websocket.matches(&Version::parse("4.9.100").unwrap()));
+        assert!(!obs_websocket.matches(&Version::parse("4.100.100").unwrap()));
+        assert!(!obs_websocket.matches(&Version::parse("5.0.0").unwrap()));
+    }
+}
diff --git a/src/lib.rs b/src/lib.rs
index 82e53e0..d2b2757 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -32,7 +32,9 @@
 
 #![warn(missing_docs, rust_2018_idioms, clippy::all)]
 
-pub use client::Client;
+pub use semver::{Version, VersionReq};
+
+pub use self::client::Client;
 
 pub mod client;
 pub mod common;
@@ -80,4 +82,11 @@ pub enum Error {
     /// event stream).
     #[error("currently not connected to obs-websocket")]
     Disconnected,
+    /// The OBS studio version of the connected instance doesn't match the required version for this
+    /// crate.
+    #[error("obs studio version {0} doesn't match required {1}")]
+    ObsStudioVersion(Version, VersionReq),
+    /// The obs-websocket plugin version doesn't match the required version for this crate.
+    #[error("obs-websocket version {0} doesn't match required {1}")]
+    ObsWebsocketVersion(Version, VersionReq),
 }