unit-tests: Export ntru_drbg_create as testable function so no linking is required

This way the plugin does not have to be linked explicitly to the test
runner, which otherwise would require that the plugin is either always
enabled to build the tests or that ifdefs are added to the Makefile.

src/libstrongswan/plugins/ntru/ntru_drbg.c

@@ -16,6 +16,7 @@
 #include "ntru_drbg.h"
 
 #include <utils/debug.h>
+#include <utils/test.h>
 
 #define	MAX_STRENGTH_BITS	256
 #define MAX_DRBG_REQUESTS	0xfffffffe
@@ -80,7 +81,7 @@ static bool update(private_ntru_drbg_t *this, chunk_t data)
 		!this->hmac->get_signature(this->hmac, this->value, NULL) ||
 	    !this->hmac->get_signature(this->hmac, ch_00, NULL) ||
 	    !this->hmac->get_signature(this->hmac, data, this->key.ptr) ||
-		!this->hmac->set_key(this->hmac, this->key) ||	
+		!this->hmac->set_key(this->hmac, this->key) ||
 	    !this->hmac->get_signature(this->hmac, this->value,
 											   this->value.ptr))
 	{
@@ -93,7 +94,7 @@ static bool update(private_ntru_drbg_t *this, chunk_t data)
 			!this->hmac->get_signature(this->hmac, this->value, NULL) ||
 			!this->hmac->get_signature(this->hmac, ch_01, NULL) ||
 			!this->hmac->get_signature(this->hmac, data, this->key.ptr) ||
-			!this->hmac->set_key(this->hmac, this->key) ||	
+			!this->hmac->set_key(this->hmac, this->key) ||
 			!this->hmac->get_signature(this->hmac, this->value,
 												   this->value.ptr))
 		{
@@ -147,7 +148,7 @@ METHOD(ntru_drbg_t, generate, bool,
 	{
 		return FALSE;
 	}
-	output = chunk_create(out, len); 
+	output = chunk_create(out, len);
 
 	if (this->reseed_counter > this->max_requests)
 	{
@@ -175,7 +176,7 @@ METHOD(ntru_drbg_t, generate, bool,
 		return FALSE;
 	}
 	this->reseed_counter++;
- 
+
 	return TRUE;
 }
 
@@ -227,7 +228,7 @@ ntru_drbg_t *ntru_drbg_create(u_int32_t strength, chunk_t pers_str,
 		DBG1(DBG_LIB, "could not instantiate HMAC-SHA256");
 		return NULL;
 	}
- 
+
 	max_requests = lib->settings->get_int(lib->settings,
 							"libstrongswan.plugins.ntru.max_drbg_requests",
 							 MAX_DRBG_REQUESTS);
@@ -275,3 +276,4 @@ ntru_drbg_t *ntru_drbg_create(u_int32_t strength, chunk_t pers_str,
 	return &this->public;
 }
 
+EXPORT_FUNCTION_FOR_TESTS(ntru, ntru_drbg_create);

src/libstrongswan/tests/Makefile.am

@@ -53,5 +53,4 @@ tests_CFLAGS = \
 tests_LDFLAGS = @COVERAGE_LDFLAGS@
 tests_LDADD = \
   $(top_builddir)/src/libstrongswan/libstrongswan.la \
-  $(top_builddir)/src/libstrongswan/plugins/ntru/libstrongswan-ntru.la \
   libtest.la

src/libstrongswan/tests/suites/test_ntru.c

@@ -17,6 +17,10 @@
 
 #include <tests/utils/test_rng.h>
 #include <plugins/ntru/ntru_drbg.h>
+#include <utils/test.h>
+
+IMPORT_FUNCTION_FOR_TESTS(ntru, ntru_drbg_create, ntru_drbg_t*,
+						  u_int32_t strength, chunk_t pers_str, rng_t *entropy)
 
 /**
  * NTRU parameter sets to test