Initial implementation of timeout.

libguac/include/client.h

@@ -57,6 +57,29 @@
  */
 #define GUAC_SYNC_THRESHOLD 500
 
+/**
+ * The time to allow between server sync messages in milliseconds. A sync
+ * message from the server will be sent every GUAC_SYNC_FREQUENCY milliseconds.
+ * As this will induce a response from a client that is not malfunctioning,
+ * this is used to detect when a client has died. This must be set to a
+ * reasonable value to avoid clients being disconnected unnecessarily due
+ * to timeout.
+ */
+#define GUAC_SYNC_FREQUENCY 5000
+
+/**
+ * The number of milliseconds to wait for messages in any phase before
+ * timing out and closing the connection with an error.
+ */
+#define GUAC_TIMEOUT      15000
+
+/**
+ * The number of microseconds to wait for messages in any phase before
+ * timing out and closing the conncetion with an error. This is always
+ * equal to GUAC_TIMEOUT * 1000.
+ */
+#define GUAC_USEC_TIMEOUT (GUAC_TIMEOUT*1000)
+
 /**
  * The amount of time to wait after handling server messages. If a client
  * plugin has a message handler, and sends instructions when server messages

libguac/src/client.c

@@ -119,9 +119,24 @@ guac_client* guac_get_client(int client_fd) {
     /* Wait for select instruction */
     for (;;) {
 
-        int result = guac_read_instruction(io, &instruction);
+        int result;
+
+        /* Wait for data until timeout */
+        result = guac_select(io, GUAC_USEC_TIMEOUT);
+        if (result == 0) {
+            guac_send_error(io, "Select timeout.");
+            guac_close(io);
+            return NULL;
+        }
+
+        /* If error occurs while waiting, exit with failure */
+        if (result < 0) {
+            guac_close(io);
+            return NULL;
+        }
+
+        result = guac_read_instruction(io, &instruction);
         if (result < 0) {
-            GUAC_LOG_ERROR("Error reading instruction while waiting for select");
             guac_close(io);
             return NULL;            
         }
@@ -194,7 +209,23 @@ guac_client* guac_get_client(int client_fd) {
     /* Wait for connect instruction */
     for (;;) {
 
-        int result = guac_read_instruction(io, &instruction);
+        int result;
+
+        /* Wait for data until timeout */
+        result = guac_select(io, GUAC_USEC_TIMEOUT);
+        if (result == 0) {
+            guac_send_error(io, "Connect timeout.");
+            guac_close(io);
+            return NULL;
+        }
+
+        /* If error occurs while waiting, exit with failure */
+        if (result < 0) {
+            guac_close(io);
+            return NULL;
+        }
+
+        result = guac_read_instruction(io, &instruction);
         if (result < 0) {
             GUAC_LOG_ERROR("Error reading instruction while waiting for connect");
             guac_close(io);
@@ -308,6 +339,21 @@ void guac_start_client(guac_client* client) {
     /* VNC Client Loop */
     for (;;) {
 
+        /* Get current time and check timeout */
+        long timestamp = __guac_current_timestamp();
+        if (timestamp - last_received_timestamp > GUAC_TIMEOUT) {
+            guac_send_error(io, "Sync timeout.");
+            guac_flush(io);
+            return;
+        }
+
+        /* If not timed out, ping client with sync */
+        if (timestamp - last_sent_timestamp > GUAC_SYNC_FREQUENCY) {
+            last_sent_timestamp = timestamp;
+            guac_send_sync(io, last_sent_timestamp);
+            guac_flush(io);
+        }
+
         /* Handle server messages */
         if (client->handle_messages) {