Ensure valid context is used in fuzz_dtlsserver

A valid ctr_drbg context is now a prerequisite for using dummy_random()

Signed-off-by: Paul Elliott <paul.elliott@arm.com>
diff --git a/programs/fuzz/fuzz_dtlsserver.c b/programs/fuzz/fuzz_dtlsserver.c
index 9a6e894..1aa757c 100644
--- a/programs/fuzz/fuzz_dtlsserver.c
+++ b/programs/fuzz/fuzz_dtlsserver.c
@@ -44,6 +44,13 @@
     unsigned char buf[4096];
     fuzzBufferOffset_t biomemfuzz;
 
+    mbedtls_ctr_drbg_init( &ctr_drbg );
+    mbedtls_entropy_init( &entropy );
+
+    if( mbedtls_ctr_drbg_seed( &ctr_drbg, dummy_entropy, &entropy,
+                               ( const unsigned char * ) pers, strlen( pers ) ) != 0 )
+        goto exit;
+
     if (initialized == 0) {
 #if defined(MBEDTLS_X509_CRT_PARSE_C) && defined(MBEDTLS_PEM_PARSE_C)
         mbedtls_x509_crt_init( &srvcert );
@@ -56,7 +63,7 @@
             return 1;
         if (mbedtls_pk_parse_key( &pkey, (const unsigned char *) mbedtls_test_srv_key,
                                  mbedtls_test_srv_key_len, NULL, 0,
-                                 dummy_random, NULL ) != 0)
+                                 dummy_random, &ctr_drbg ) != 0)
             return 1;
 #endif
         dummy_init();
@@ -65,15 +72,8 @@
     }
     mbedtls_ssl_init( &ssl );
     mbedtls_ssl_config_init( &conf );
-    mbedtls_ctr_drbg_init( &ctr_drbg );
-    mbedtls_entropy_init( &entropy );
     mbedtls_ssl_cookie_init( &cookie_ctx );
 
-    if( mbedtls_ctr_drbg_seed( &ctr_drbg, dummy_entropy, &entropy,
-                              (const unsigned char *) pers, strlen( pers ) ) != 0 )
-        goto exit;
-
-
     if( mbedtls_ssl_config_defaults( &conf,
                                     MBEDTLS_SSL_IS_SERVER,
                                     MBEDTLS_SSL_TRANSPORT_DATAGRAM,