fix: Swallow exceptions caused by user callbacks

Otherwise, the process will crash.

diff --git a/src/lib/lldpctl.hpp b/src/lib/lldpctl.hpp
index 1baba1aeffc2917cb983ce75d5728c2cb55d0f78..512954ac265578e9d52cd3a2a3a37449846a3a68 100644 (file)
--- a/src/lib/lldpctl.hpp
+++ b/src/lib/lldpctl.hpp
@@ -473,6 +473,9 @@ class LldpWatch {
         * @param callback  Optional callback to trigger on remote changes.
         *                  Additionally, interface specific callbacks can be registered
         *                                      using @ref RegisterInterfaceCallback.
+        *
+        * @note Exceptions raised by @p callback will be swallowed 
+        *       to avoid a crash of the underlying C library.
         */
        explicit LldpWatch(
            const std::optional<ChangeCallback> &callback = std::nullopt)
@@ -515,6 +518,9 @@ class LldpWatch {
         * @brief Register an interface specific callback on remote changes.
         *
         * @note Only up to one callback can be registered per interface.
+        * 
+        * @note Exceptions raised by @p callback will be swallowed (except during registration)
+        *       to avoid a crash of the underlying C library.
         *
         * @param if_name       The local interface to monitor.
         * @param callback      Callback to trigger on remote changes.
@@ -590,7 +596,7 @@ class LldpWatch {
 
     private:
        static void WatchCallback(lldpctl_change_t change, lldpctl_atom_t *interface,
-           lldpctl_atom_t *neighbor, void *p)
+           lldpctl_atom_t *neighbor, void *p) noexcept
        {
                /* These LldpAtoms don't extend the lifetime of the underlying
                 * connection as it's owned by the library. */
@@ -628,12 +634,17 @@ class LldpWatch {
                }
 
                /* Run the callbacks without holding the mutex. */
-               if (general_cb.has_value()) {
-                       (*general_cb)(if_name, change, interface_atom, neighbor_atom);
+               try {
+                       if (general_cb.has_value()) {
+                               (*general_cb)(if_name, change, interface_atom, neighbor_atom);
+                       }
+       
+                       if (interface_cb.has_value()) {
+                               (*interface_cb)(if_name, change, interface_atom, neighbor_atom);
+                       }
                }
-
-               if (interface_cb.has_value()) {
-                       (*interface_cb)(if_name, change, interface_atom, neighbor_atom);
+               catch (...) {
+                       /* Swallow any exception to avoid letting it propagate into the C library which would kill the process. */
                }
 
                /* Decrement active callbacks and notify waiting threads. */