Read frame.

src/mpvctl/mpv_framed.rs

@@ -18,8 +18,19 @@ impl MpvFramed {
     pub async fn read_frame(
         &mut self,
     ) -> Result<Option<serde_json::Value>, Box<dyn std::error::Error>> {
-        //
-        todo!()
+        loop {
+            if let Some(frame) = self.parse_frame()? {
+                return Ok(Some(frame));
+            }
+
+            if 0 == self.socket_read.read_buf(&mut self.buffer).await? {
+                if self.buffer.is_empty() {
+                    return Ok(None);
+                } else {
+                    return Err("connection reset by peer".into());
+                }
+            }
+        }
     }
 
     fn parse_frame(&mut self) -> Result<Option<serde_json::Value>, Box<dyn std::error::Error>> {