From b900c401fef3838fef5c78e6b4527dc6b07e4ac6 Mon Sep 17 00:00:00 2001
From: billz <billzimmerman@gmail.com>
Date: Sun, 27 Apr 2025 09:07:58 -0700
Subject: [PATCH] Initial commit

---
 installers/raspap-network-monitor.c | 104 ++++++++++++++++++++++++++++
 1 file changed, 104 insertions(+)
 create mode 100644 installers/raspap-network-monitor.c

diff --git a/installers/raspap-network-monitor.c b/installers/raspap-network-monitor.c
new file mode 100644
index 00000000..89acaf6e
--- /dev/null
+++ b/installers/raspap-network-monitor.c
@@ -0,0 +1,104 @@
+// network-monitor.c
+
+/*
+RaspAP Network Activity Monitor
+Author: @billz <billzimmerman@gmail.com>
+Author URI: https://github.com/billz/
+License: GNU General Public License v3.0
+License URI: https://github.com/raspap/raspap-webgui/blob/master/LICENSE
+*/
+
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <poll.h>
+#include <sys/timerfd.h>
+#include <errno.h>
+#include <stdint.h>
+
+#define TMPFILE "/dev/shm/net_activity"
+#define POLL_INTERVAL_MS 100 // 100 milliseconds
+
+unsigned long read_interface_bytes(const char *iface) {
+    FILE *fp = fopen("/proc/net/dev", "r");
+    if (!fp) return 0;
+
+    char line[512];
+    unsigned long rx = 0, tx = 0;
+
+    while (fgets(line, sizeof(line), fp)) {
+        if (strstr(line, iface)) {
+            char *ptr = strchr(line, ':');
+            if (ptr) {
+                sscanf(ptr + 1, "%lu %*u %*u %*u %*u %*u %*u %*u %lu", &rx, &tx);
+            }
+            break;
+        }
+    }
+
+    fclose(fp);
+    return rx + tx;
+}
+
+int main(int argc, char *argv[]) {
+    if (argc < 2) {
+        fprintf(stderr, "Usage: %s <interface>\n", argv[0]);
+        return EXIT_FAILURE;
+    }
+
+    const char *iface = argv[1];
+    unsigned long prev_total = read_interface_bytes(iface);
+
+    // create a timerfd
+    int tfd = timerfd_create(CLOCK_MONOTONIC, 0);
+    if (tfd == -1) {
+        perror("timerfd_create");
+        return EXIT_FAILURE;
+    }
+
+    struct itimerspec timer;
+    timer.it_interval.tv_sec = 0;
+    timer.it_interval.tv_nsec = POLL_INTERVAL_MS * 1000000; // interval
+    timer.it_value.tv_sec = 0;
+    timer.it_value.tv_nsec = POLL_INTERVAL_MS * 1000000;    // initial expiration
+
+    if (timerfd_settime(tfd, 0, &timer, NULL) == -1) {
+        perror("timerfd_settime");
+        close(tfd);
+        return EXIT_FAILURE;
+    }
+
+    struct pollfd fds;
+    fds.fd = tfd;
+    fds.events = POLLIN;
+
+    for (;;) {
+        int ret = poll(&fds, 1, -1);
+        if (ret == -1) {
+            perror("poll");
+            break;
+        }
+
+        if (fds.revents & POLLIN) {
+            uint64_t expirations;
+            read(tfd, &expirations, sizeof(expirations)); // clear timer
+
+            unsigned long curr_total = read_interface_bytes(iface);
+            unsigned long diff = (curr_total >= prev_total) ? (curr_total - prev_total) : 0;
+            prev_total = curr_total;
+
+            FILE *out = fopen(TMPFILE, "w");
+            if (out) {
+                fprintf(out, "%lu\n", diff);
+                fclose(out);
+            }
+        }
+    }
+
+    close(tfd);
+    return EXIT_SUCCESS;
+}
+