GUACAMOLE-623: Add outbound message buffer.

src/protocols/kubernetes/client.c

@@ -67,17 +67,8 @@ int guac_kubernetes_client_free_handler(guac_client* client) {
     guac_kubernetes_client* kubernetes_client =
         (guac_kubernetes_client*) client->data;
 
-    /* Clean up recording, if in progress */
+    /* Wait client thread to terminate */
-    if (kubernetes_client->recording != NULL)
-        guac_common_recording_free(kubernetes_client->recording);
-
-    /* Kill terminal */
-    guac_terminal_free(kubernetes_client->term);
-
-    /* TODO: Wait for and free WebSocket session, if connected */
-    /*if (kubernetes_client->websocket != NULL) {
     pthread_join(kubernetes_client->client_thread, NULL);
-    }*/
 
     /* Free settings */
     if (kubernetes_client->settings != NULL)

src/protocols/kubernetes/kubernetes.c

@@ -206,6 +206,8 @@ static void* guac_kubernetes_input_thread(void* data) {
 
 void* guac_kubernetes_client_thread(void* data) {
 
+    struct lws_context* context = NULL;
+
     guac_client* client = (guac_client*) data;
     guac_kubernetes_client* kubernetes_client =
         (guac_kubernetes_client*) client->data;
@@ -236,7 +238,7 @@ void* guac_kubernetes_client_thread(void* data) {
     if (kubernetes_client->term == NULL) {
         guac_client_abort(client, GUAC_PROTOCOL_STATUS_SERVER_ERROR,
                 "Terminal initialization failed");
-        return NULL;
+        goto fail;
     }
 
     /* Set up typescript, if requested */
@@ -295,11 +297,11 @@ void* guac_kubernetes_client_thread(void* data) {
     }
 
     /* Create libwebsockets context */
-    struct lws_context* context = lws_create_context(&context_info);
+    context = lws_create_context(&context_info);
     if (!context) {
         guac_client_abort(client, GUAC_PROTOCOL_STATUS_SERVER_ERROR,
                 "Initialization of libwebsockets failed");
-        return NULL;
+        goto fail;
     }
 
     /* FIXME: Generate path dynamically */
@@ -311,13 +313,16 @@ void* guac_kubernetes_client_thread(void* data) {
     if (kubernetes_client->wsi == NULL) {
         guac_client_abort(client, GUAC_PROTOCOL_STATUS_SERVER_ERROR,
                 "Connection via libwebsockets failed");
-        return NULL;
+        goto fail;
     }
 
+    /* Init outbound message buffer */
+    pthread_mutex_init(&(kubernetes_client->outbound_message_lock), NULL);
+
     /* Start input thread */
     if (pthread_create(&(input_thread), NULL, guac_kubernetes_input_thread, (void*) client)) {
         guac_client_abort(client, GUAC_PROTOCOL_STATUS_SERVER_ERROR, "Unable to start input thread");
-        return NULL;
+        goto fail;
     }
 
     /* As long as client is connected, continue polling libwebsockets */
@@ -330,10 +335,22 @@ void* guac_kubernetes_client_thread(void* data) {
     }
 
     /* Kill client and Wait for input thread to die */
+    guac_terminal_stop(kubernetes_client->term);
     guac_client_stop(client);
     pthread_join(input_thread, NULL);
 
-    /* All done with libwebsockets */
+fail:
+
+    /* Kill and free terminal, if allocated */
+    if (kubernetes_client->term != NULL)
+        guac_terminal_free(kubernetes_client->term);
+
+    /* Clean up recording, if in progress */
+    if (kubernetes_client->recording != NULL)
+        guac_common_recording_free(kubernetes_client->recording);
+
+    /* Free WebSocket context if successfully allocated */
+    if (context != NULL)
         lws_context_destroy(context);
 
     guac_client_log(client, GUAC_LOG_INFO, "Kubernetes connection ended.");

src/protocols/kubernetes/kubernetes.h

@@ -55,6 +55,37 @@
  */
 #define GUAC_KUBERNETES_CHANNEL_RESIZE 4
 
+/**
+ * The maximum number of messages to allow within the outbound message buffer.
+ * If messages are sent despite the buffer being full, those messages will be
+ * dropped.
+ */
+#define GUAC_KUBERNETES_MAX_OUTBOUND_MESSAGES 8
+
+/**
+ * An outbound message to be received by Kubernetes over WebSocket.
+ */
+typedef struct guac_kubernetes_message {
+
+    /**
+     * The index of the channel receiving the data, such as
+     * GUAC_KUBERNETES_CHANNEL_STDIN.
+     */
+    uint8_t channel;
+
+    /**
+     * The data that should be sent to Kubernetes (along with the channel
+     * index).
+     */
+    char data[1024];
+
+    /**
+     * The length of the data to be sent, excluding the channel index.
+     */
+    int length;
+
+} guac_kubernetes_message;
+
 /**
  * Kubernetes-specific client data.
  */
@@ -70,6 +101,33 @@ typedef struct guac_kubernetes_client {
      */
     struct lws* wsi;
 
+    /**
+     * Outbound message ring buffer for outbound WebSocket messages. As
+     * libwebsockets uses an event loop for all operations, outbound messages
+     * may be sent only in context of a particular event received via a
+     * callback. Until that event is received, pending data must accumulate in
+     * a buffer.
+     */
+    guac_kubernetes_message outbound_messages[GUAC_KUBERNETES_MAX_OUTBOUND_MESSAGES];
+
+    /**
+     * The number of messages currently waiting in the outbound message
+     * buffer.
+     */
+    int outbound_messages_waiting;
+
+    /**
+     * The index of the oldest entry in the outbound message buffer. Newer
+     * messages follow this entry.
+     */
+    int outbound_messages_top;
+
+    /**
+     * Lock which is acquired when the outbound message buffer is being read
+     * or manipulated.
+     */
+    pthread_mutex_t outbound_message_lock;
+
     /**
      * The Kubernetes client thread.
      */