Update tungstenite crates to 0.20

This upgrades tungstenite and tokio-tungstenite to 0.20 in order to
address CVE-2023-43669/GHSA-9mcr-873m-xcxp.

Cargo.toml

@@ -137,7 +137,7 @@ syn = "1.0"
 tempfile = "3.2"
 thiserror = "1.0"
 tokio = "1"
-tokio-tungstenite = "0.17"
+tokio-tungstenite = "0.20"
 tokio-util = "0.7"
 toml = "0.7.6"
 tracing = "0.1.35"

bin/propolis-server/src/lib/mock_server.rs

@@ -329,8 +329,12 @@ async fn instance_serial(
     query: Query<api::InstanceSerialConsoleStreamRequest>,
     websock: WebsocketConnection,
 ) -> dropshot::WebsocketChannelResult {
-    let config =
-        WebSocketConfig { max_send_queue: Some(4096), ..Default::default() };
+    let config = WebSocketConfig {
+        // tune the buffer size limits down (compared to the defaults)
+        write_buffer_size: 4096,
+        max_write_buffer_size: 8192,
+        ..Default::default()
+    };
     let mut ws_stream = WebSocketStream::from_raw_socket(
         websock.into_inner(),
         Role::Server,

bin/propolis-server/src/lib/server.rs

@@ -831,8 +831,13 @@ async fn instance_serial(
     let vm = ctx.vm().await?;
     let serial = vm.com1().clone();
 
-    let config =
-        WebSocketConfig { max_send_queue: Some(4096), ..Default::default() };
+    let config = WebSocketConfig {
+        // tune the buffer size limits down (compared to the defaults)
+        // TODO: tuning for this could be explored
+        write_buffer_size: 4096,
+        max_write_buffer_size: 8192,
+        ..Default::default()
+    };
     let mut ws_stream = WebSocketStream::from_raw_socket(
         websock.into_inner(),
         Role::Server,

lib/propolis-client/src/lib.rs

@@ -140,7 +140,9 @@ pub mod support {
                 .send()
                 .await
                 .map_err(|e| {
-                    WSError::Http(http::Response::new(Some(e.to_string())))
+                    WSError::Http(http::Response::new(Some(
+                        e.to_string().into_bytes(),
+                    )))
                 })?
                 .into_inner();
 
@@ -190,9 +192,10 @@ pub mod support {
                 tokio::time::sleep(delay).await;
                 Ok(Box::new(stream))
             } else {
-                Err(WSError::Http(http::Response::new(Some(format!(
-                    "no duplex connection found for address {address}"
-                )))))
+                Err(WSError::Http(http::Response::new(Some(
+                    format!("no duplex connection found for address {address}")
+                        .into_bytes(),
+                ))))
             }
         }
     }