Add Loader stats source files.

src/loader/utils/stats.c

@@ -0,0 +1,48 @@
+#include <loader/utils/stats.h>
+
+/**
+ * Calculates and displays packet counters/stats.
+ * 
+ * @param stats_map The stats map BPF FD.
+ * @param cpus The amount of CPUs the host has.
+ * 
+ * @return 0 on success or 1 on failure.
+ */
+int CalculateStats(int stats_map, int cpus)
+{
+    u32 key = 0;
+
+    stats_t stats[MAX_CPUS];
+    memset(stats, 0, sizeof(stats));
+
+    u64 allowed = 0;
+    u64 dropped = 0;
+    u64 passed = 0;
+    
+    if (bpf_map_lookup_elem(stats_map, &key, stats) != 0)
+    {
+        return EXIT_FAILURE;
+    }
+
+    for (int i = 0; i < cpus; i++)
+    {
+        // Although this should NEVER happen, I'm seeing very strange behavior in the following GitHub issue.
+        // https://github.com/gamemann/XDP-Firewall/issues/10
+        // Therefore, before accessing stats[i], make sure the pointer to the specific CPU ID is not NULL.
+        if (&stats[i] == NULL)
+        {
+            fprintf(stderr, "Stats array at CPU ID #%d is NULL! Skipping...\n", i);
+
+            continue;
+        }
+
+        allowed += stats[i].allowed;
+        dropped += stats[i].dropped;
+        passed += stats[i].passed;
+    }
+
+    fflush(stdout);
+    fprintf(stdout, "\rAllowed: %llu | Dropped: %llu | Passed: %llu", allowed, dropped, passed);
+
+    return EXIT_SUCCESS;
+}

src/loader/utils/stats.h

@@ -0,0 +1,13 @@
+#pragma once
+
+#include <bpf.h>
+#include <libbpf.h>
+#include <xdp/libxdp.h>
+
+#include  <common/all.h>
+
+#include <loader/utils/cmdline.h>
+#include <loader/utils/config.h>
+#include <loader/utils/helpers.h>
+
+int CalculateStats(int stats_map, int cpus);