2026-04-29

internal/pkg/config/util.go

@@ -0,0 +1,58 @@
+package config
+
+import (
+	"fmt"
+	"net"
+)
+
+func GetOutboundIP() net.IP {
+	conn, err := net.Dial("udp", "192.0.2.1:80")
+	if err != nil {
+		return nil
+	}
+	defer func() { _ = conn.Close() }()
+	localAddr := conn.LocalAddr().(*net.UDPAddr)
+	return localAddr.IP
+}
+
+func GetIPNetForIP(ip net.IP) (*net.IPNet, error) {
+	interfaces, err := net.Interfaces()
+	if err != nil {
+		return nil, fmt.Errorf("failed to get network interfaces: %v", err)
+	}
+
+	for _, iface := range interfaces {
+		// skip interfaces that are down or not relevant
+		if iface.Flags&net.FlagUp == 0 {
+			continue
+		}
+
+		addrs, err := iface.Addrs()
+		if err != nil {
+			continue // try next interface
+		}
+
+		for _, addr := range addrs {
+			// We expect addr to be of type *net.IPNet.
+			var ipNet *net.IPNet
+			switch v := addr.(type) {
+			case *net.IPNet:
+				ipNet = v
+			case *net.IPAddr:
+				// Wrap net.IPAddr in an IPNet with its default mask.
+				ipNet = &net.IPNet{IP: v.IP, Mask: v.IP.DefaultMask()}
+			}
+
+			if ipNet == nil {
+				continue
+			}
+
+			// Check if the IP matches (for IPv4, Equal works well)
+			if ipNet.IP.Equal(ip) {
+				return ipNet, nil
+			}
+		}
+	}
+
+	return nil, fmt.Errorf("could not find IPNet for IP %v", ip)
+}