up

internal/integrations/udp/reuse_unix.go

@@ -0,0 +1,18 @@
+//go:build !windows
+
+package udp
+
+import "golang.org/x/sys/unix"
+
+// setSocketReuse enables SO_REUSEADDR + SO_REUSEPORT on Linux/macOS so
+// multiple processes can share a multicast UDP port (matches the Windows
+// behaviour with SO_REUSEADDR).
+func setSocketReuse(fd uintptr) error {
+	if err := unix.SetsockoptInt(int(fd), unix.SOL_SOCKET, unix.SO_REUSEADDR, 1); err != nil {
+		return err
+	}
+	// SO_REUSEPORT isn't defined on every Unix; the syscall returning
+	// ENOPROTOOPT is fine to ignore.
+	_ = unix.SetsockoptInt(int(fd), unix.SOL_SOCKET, unix.SO_REUSEPORT, 1)
+	return nil
+}