Put the default set of TLSv1.3 ciphersuites in a header file

Reviewed-by: NTim Hudson <tjh@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/5392)

include/openssl/ssl.h

@@ -169,8 +169,13 @@ extern "C" {
 /*
  * The following cipher list is used by default. It also is substituted when
  * an application-defined cipher list string starts with 'DEFAULT'.
+ * This applies to ciphersuites for TLSv1.2 and below.
  */
 # define SSL_DEFAULT_CIPHER_LIST "ALL:!COMPLEMENTOFDEFAULT:!eNULL"
+/* This is the default set of TLSv1.3 ciphersuites */
+# define TLS_DEFAULT_CIPHERSUITES "TLS_AES_256_GCM_SHA384:" \
+                                  "TLS_CHACHA20_POLY1305_SHA256:" \
+                                  "TLS_AES_128_GCM_SHA256"
 /*
  * As of OpenSSL 1.0.0, ssl_create_cipher_list() in ssl/ssl_ciph.c always
  * starts with a reasonable order, and all we have to do for DEFAULT is

ssl/ssl_lib.c

@@ -3019,10 +3019,7 @@ SSL_CTX *SSL_CTX_new(const SSL_METHOD *meth)
         goto err;
 #endif
 
-    if (!SSL_CTX_set_ciphersuites(ret,
-            "TLS_AES_256_GCM_SHA384:"
-            "TLS_CHACHA20_POLY1305_SHA256:"
-            "TLS_AES_128_GCM_SHA256"))
+    if (!SSL_CTX_set_ciphersuites(ret, TLS_DEFAULT_CIPHERSUITES))
         goto err;
 
     if (!ssl_create_cipher_list(ret->method,