[gupnp] service-action: Protect against unsent message use

[Jens Georg <jensgeorg src gnome org>]

commit 8a349541f10b774ac8128bfb0e25ddbb405e6033
Author: Jens Georg <mail jensge org>
Date:   Wed May 19 19:40:41 2021 +0200

    service-action: Protect against unsent message use
    
    If the action wasn't sent, do not crash

 libgupnp/gupnp-service-proxy-action.c | 9 +++++++++
 1 file changed, 9 insertions(+)
---
diff --git a/libgupnp/gupnp-service-proxy-action.c b/libgupnp/gupnp-service-proxy-action.c
index 3b3a7c1..2fd10d5 100644
--- a/libgupnp/gupnp-service-proxy-action.c
+++ b/libgupnp/gupnp-service-proxy-action.c
@@ -61,6 +61,15 @@ check_action_response (G_GNUC_UNUSED GUPnPServiceProxy *proxy,
         xmlDoc *response;
         int code;
 
+        if (action->msg == NULL) {
+                g_set_error (error,
+                             GUPNP_SERVER_ERROR,
+                             GUPNP_SERVER_ERROR_INVALID_RESPONSE,
+                             "No message, the action was not sent?");
+
+                return NULL;
+        }
+
         /* Check for errors */
         switch (action->msg->status_code) {
         case SOUP_STATUS_OK: