kernel: Make range of SPIs for IPsec SAs configurable

src/libcharon/kernel/kernel_interface.h

@@ -56,6 +56,12 @@ typedef enum kernel_feature_t kernel_feature_t;
 #include <kernel/kernel_ipsec.h>
 #include <kernel/kernel_net.h>
 
+/**
+ * Default range for SPIs requested from kernels
+ */
+#define KERNEL_SPI_MIN 0xc0000000
+#define KERNEL_SPI_MAX 0xcfffffff
+
 /**
  * Bitfield of optional features a kernel backend supports.
  *