Add sanity check for configuration method

.wolfssl_known_macro_extras

@@ -599,6 +599,7 @@ WOLFSSL_CLANG_TIDY
 WOLFSSL_COMMERCIAL_LICENSE
 WOLFSSL_CONTIKI
 WOLFSSL_CRL_ALLOW_MISSING_CDP
+WOLFSSL_CUSTOM_CONFIG
 WOLFSSL_DILITHIUM_ASSIGN_KEY
 WOLFSSL_DILITHIUM_MAKE_KEY_SMALL_MEM
 WOLFSSL_DILITHIUM_NO_ASN1

examples/echoclient/echoclient.c

@@ -24,10 +24,10 @@
     #include <config.h>
 #endif
 
-#include <wolfssl/wolfcrypt/settings.h>
 #ifndef WOLFSSL_USER_SETTINGS
     #include <wolfssl/options.h>
 #endif
+#include <wolfssl/wolfcrypt/settings.h>
 
 /* Force enable the compatibility macros for this example */
 #undef TEST_OPENSSL_COEXIST

sslSniffer/sslSnifferTest/snifftest.c

@@ -24,6 +24,9 @@
     #include <config.h>
 #endif
 
+#ifndef WOLFSSL_USER_SETTINGS
+    #include <wolfssl/options.h>
+#endif
 #include <wolfssl/wolfcrypt/settings.h>
 #include <wolfssl/wolfcrypt/types.h>
 #include <wolfssl/wolfcrypt/logging.h>

tests/srp.c

@@ -24,6 +24,9 @@
     #include <config.h>
 #endif
 
+#ifndef WOLFSSL_USER_SETTINGS
+    #include <wolfssl/options.h>
+#endif
 #include <wolfssl/wolfcrypt/settings.h>
 
 #include <tests/unit.h>

testsuite/testsuite.c

@@ -24,10 +24,10 @@
     #include <config.h>
 #endif
 
-#include <wolfssl/wolfcrypt/settings.h>
 #ifndef WOLFSSL_USER_SETTINGS
     #include <wolfssl/options.h>
 #endif
+#include <wolfssl/wolfcrypt/settings.h>
 
 #undef TEST_OPENSSL_COEXIST /* can't use this option with this example */
 #undef OPENSSL_COEXIST /* can't use this option with this example */

wolfssl/wolfcrypt/settings.h

@@ -28,6 +28,8 @@
  *
  *   ./configure CFLAGS="-DFEATURE_FLAG_TO_DEFINE -UFEATURE_FLAG_TO_CLEAR [...]"
  *
+ *   To build using a custom configuration method, define WOLFSSL_CUSTOM_CONFIG
+ *
  *   For more information see:
  *
  *   https://www.wolfssl.com/how-do-i-manage-the-build-configuration-of-wolfssl/
@@ -326,6 +328,12 @@
     /* NOTE: cyassl_nucleus_defs.h is akin to user_settings.h */
     #include "nucleus.h"
     #include "os/networking/ssl/lite/cyassl_nucleus_defs.h"
+#elif !defined(BUILDING_WOLFSSL) && !defined(WOLFSSL_OPTIONS_H) && \
+      !defined(WOLFSSL_CUSTOM_CONFIG)
+    /* This error indicates that the settings header may not be included before
+     * other wolfSSL headers. If you are using a custom configuration method,
+     * define WOLFSSL_CUSTOM_CONFIG to override this error. */
+    #error "No configuration for wolfSSL detected, check header order"
 #endif
 
 #include <wolfssl/wolfcrypt/visibility.h>