utils/stats: fetch ReceivedBytes and TransmittedBytes

use "wg show all transfer" to collect stats for the peers, use public key to distinguish peers

util/pkg/stats/stats.go

@@ -0,0 +1,75 @@
+package stats
+
+import (
+	"fmt"
+	"os/exec"
+	"strings"
+)
+
+func GetWireGuardStats() (map[string]map[string]int64, error) {
+	cmd := exec.Command("sudo", "wg", "show", "all", "transfer")
+
+	output, err := cmd.CombinedOutput()
+	if err != nil {
+		return nil, fmt.Errorf("failed to execute 'sudo wg show all transfer': %v", err)
+	}
+
+	stats := make(map[string]map[string]int64)
+	lines := strings.Split(string(output), "\n")
+	for _, line := range lines {
+		fields := strings.Fields(line)
+		if len(fields) >= 4 {
+			peerPublicKey := fields[1]
+			receivedBytes := fields[2]
+			transmittedBytes := fields[3]
+
+			if _, ok := stats[peerPublicKey]; !ok {
+				stats[peerPublicKey] = make(map[string]int64)
+			}
+
+			stats[peerPublicKey]["ReceivedBytes"] = parseBytes(receivedBytes)
+			stats[peerPublicKey]["TransmittedBytes"] = parseBytes(transmittedBytes)
+		}
+	}
+
+	return stats, nil
+}
+
+type WireGuardStats struct {
+	Interface        string
+	PeerPublicKey    string
+	ReceivedBytes    int64
+	TransmittedBytes int64
+}
+
+func getWireGuardStatsForPeer(publicKey string) (*WireGuardStats, error) {
+	cmd := exec.Command("sudo", "wg", "show", "all", "transfer")
+
+	output, err := cmd.CombinedOutput()
+	if err != nil {
+		return nil, fmt.Errorf("failed to execute 'sudo wg show all transfer': %v", err)
+	}
+
+	lines := strings.Split(string(output), "\n")
+	for _, line := range lines {
+		fields := strings.Fields(line)
+		if len(fields) >= 4 && fields[1] == publicKey {
+			return &WireGuardStats{
+				Interface:        fields[0],
+				PeerPublicKey:    fields[1],
+				ReceivedBytes:    parseBytes(fields[2]),
+				TransmittedBytes: parseBytes(fields[3]),
+			}, nil
+		}
+	}
+
+	return nil, fmt.Errorf("stats not found for public key: %s", publicKey)
+}
+
+func parseBytes(bytesStr string) int64 {
+	var unit int64
+
+	fmt.Sscanf(bytesStr, "%d", &unit)
+
+	return unit
+}