added a MODP_NULL Diffie Hellman group to avoid calculation overhead in load-testing

src/libstrongswan/crypto/diffie_hellman.c

@@ -36,5 +36,7 @@ ENUM_NEXT(diffie_hellman_group_names, MODP_2048_BIT, ECP_521_BIT, MODP_1536_BIT,
 ENUM_NEXT(diffie_hellman_group_names, ECP_192_BIT, ECP_224_BIT, ECP_521_BIT,
 	"ECP_192_BIT",
 	"ECP_224_BIT");
-ENUM_END(diffie_hellman_group_names, ECP_224_BIT);
+ENUM_NEXT(diffie_hellman_group_names, MODP_NULL, MODP_NULL, ECP_224_BIT,
+	"MODP_NULL");
+ENUM_END(diffie_hellman_group_names, MODP_NULL);
 

src/libstrongswan/crypto/diffie_hellman.h

@@ -52,6 +52,8 @@ enum diffie_hellman_group_t {
 	ECP_521_BIT   = 21,
 	ECP_192_BIT   = 25,
 	ECP_224_BIT   = 26,
+	/** insecure NULL diffie hellman group for testing, in PRIVATE USE */
+	MODP_NULL = 1024,
 };
 
 /**