Set custom LibXDP/LibBPF logging.

README.md

@@ -118,7 +118,7 @@ The following table quickly explains the data types used within the configuratio
 ### Main
 | Name | Type | Default | Description |
 | ---- | ---- | ------- | ----------- |
-| verbose | int | `1` | The verbose level for logging (0 - 4 supported so far). |
+| verbose | int | `1` | The verbose level for logging (0 - 5 supported so far). |
 | log_file | string | `/var/log/xdpfw/xdpfw.log` | The log file location. If the string is empty (`""`), the log file is disabled. |
 | interface | string | `NULL` | The network interface name to attach the XDP program to (usually retrieved with `ip a` or `ifconfig`). |
 | update_time | uint | `0` | How often to update the config and filtering rules from the file system in seconds (0 disables). |
@@ -316,6 +316,11 @@ I recommend only enabling filter logging at this time for debugging. If you'd li
 
 I will most likely implement functionality to rate limit log messages from XDP in the future.
 
+### LibBPF Logging
+When loading the BPF/XDP program through LibXDP/LibBPF, logging is disabled unless if the `verbose` log setting is set to `5` or higher.
+
+If the tool fails to load or attach the XDP program, it is recommended you set `verbose` to 5 or above so LibXDP outputs specific warnings and errors.
+
 ## My Other XDP Projects
 I just wanted to share other open source projects I've made which also utilize XDP (or AF_XDP sockets) for those interested. I hope code from these other projects help programmers trying to utilize XDP in their own projects!
 

src/loader/prog.c

@@ -85,8 +85,18 @@ int main(int argc, char *argv[])
 
     LogMsg(&cfg, 2, 0, "Loading XDP/BPF program at '%s'...", XDP_OBJ_PATH);
 
+    // Determine custom LibBPF log level.
+    int silent = 1;
+
+    if (cfg.verbose > 4)
+    {
+        silent = 0;
+    }
+
+    SetLibBPFLogMode(silent);
+
     // Load BPF object.
-    struct xdp_program *prog = LoadBpfObj(XDP_OBJ_PATH);
+    struct xdp_program *prog = LoadBpfObj(XDP_OBJ_PATH, strict);
 
     if (prog == NULL)
     {

src/loader/utils/xdp.c

@@ -36,14 +36,44 @@ int FindMapFd(struct xdp_program *prog, const char *map_name)
         return fd;
 }
 
+/**
+ * Custom print function for LibBPF that doesn't print anything (silent mode).
+ * 
+ * @param level The current LibBPF log level.
+ * @param format The message format.
+ * @param args Format arguments for the message.
+ * 
+ * @return void
+ */
+static int silent_libbpf_log(enum libbpf_print_level level, const char *format, va_list args)
+{
+    return 0;
+}
+
+/**
+ * Sets custom LibBPF log mode.
+ * 
+ * @param silent If 1, disables LibBPF logging entirely.
+ * 
+ * @return void
+ */
+void SetLibBPFLogMode(int silent)
+{
+    if (silent)
+    {
+        libbpf_set_print(silent_libbpf_log);
+    }
+}
+
 /**
  * Loads a BPF object file.
  * 
  * @param file_name The path to the BPF object file.
+ * @param strict Whether to enable strict mode.
  * 
  * @return XDP program structure (pointer) or NULL.
  */
-struct xdp_program *LoadBpfObj(const char *file_name)
+struct xdp_program *LoadBpfObj(const char *file_name, int strict)
 {
     struct xdp_program *prog = xdp_program__open_file(file_name, "xdp_prog", NULL);
 

src/loader/utils/xdp.h

@@ -11,6 +11,7 @@
 #define XDP_OBJ_PATH "/etc/xdpfw/xdp_prog.o"
 
 int FindMapFd(struct xdp_program *prog, const char *map_name);
-struct xdp_program *LoadBpfObj(const char *file_name);
+void SetLibBPFLogMode(int silent);
+struct xdp_program *LoadBpfObj(const char *file_name, int strict);
 int AttachXdp(struct xdp_program *prog, char** mode, int ifidx, u8 detach, cmdline_t *cmd);
 void UpdateFilters(int filters_map, config__t *cfg);