From 381eaa59763d58ba4ab82acee4007b3771bd2d01 Mon Sep 17 00:00:00 2001
From: Hanno Becker <hanno.becker@arm.com>
Date: Wed, 12 Jun 2019 14:43:01 +0100
Subject: [PATCH] Remove min/maj version from SSL context if only one version
 enabled

If the minor/major version is enforced at compile-time, the `major_ver`
and `minor_ver` fields in `mbedtls_ssl_context` are redundant and can
be removed.
---
 include/mbedtls/ssl.h          | 16 ++++++++++++++++
 include/mbedtls/ssl_internal.h | 10 ++++++++++
 library/ssl_cli.c              |  9 +++++++++
 library/ssl_srv.c              |  4 ++++
 4 files changed, 39 insertions(+)

diff --git a/include/mbedtls/ssl.h b/include/mbedtls/ssl.h
index ee8bd818b..5e9954462 100644
--- a/include/mbedtls/ssl.h
+++ b/include/mbedtls/ssl.h
@@ -63,6 +63,18 @@
 #include "platform_time.h"
 #endif
 
+#if defined(MBEDTLS_SSL_CONF_MAX_MAJOR_VER) && \
+    defined(MBEDTLS_SSL_CONF_MIN_MAJOR_VER) && \
+    ( MBEDTLS_SSL_CONF_MAX_MAJOR_VER == MBEDTLS_SSL_CONF_MIN_MAJOR_VER )
+#define MBEDTLS_SSL_CONF_FIXED_MAJOR_VER MBEDTLS_SSL_CONF_MIN_MAJOR_VER
+#endif
+
+#if defined(MBEDTLS_SSL_CONF_MAX_MINOR_VER) && \
+    defined(MBEDTLS_SSL_CONF_MIN_MINOR_VER) && \
+    ( MBEDTLS_SSL_CONF_MAX_MINOR_VER == MBEDTLS_SSL_CONF_MIN_MINOR_VER )
+#define MBEDTLS_SSL_CONF_FIXED_MINOR_VER MBEDTLS_SSL_CONF_MIN_MINOR_VER
+#endif
+
 /*
  * SSL Error codes
  */
@@ -1229,8 +1241,12 @@ struct mbedtls_ssl_context
                                   renego_max_records is < 0           */
 #endif /* MBEDTLS_SSL_RENEGOTIATION */
 
+#if !defined(MBEDTLS_SSL_CONF_FIXED_MAJOR_VER)
     int major_ver;              /*!< equal to  MBEDTLS_SSL_MAJOR_VERSION_3    */
+#endif /* !MBEDTLS_SSL_CONF_FIXED_MAJOR_VER */
+#if !defined(MBEDTLS_SSL_CONF_FIXED_MINOR_VER)
     int minor_ver;              /*!< either 0 (SSL3) or 1 (TLS1.0)    */
+#endif /* !MBEDTLS_SSL_CONF_FIXED_MINOR_VER */
 
 #if defined(MBEDTLS_SSL_DTLS_BADMAC_LIMIT)
     unsigned badmac_seen;       /*!< records with a bad MAC received    */
diff --git a/include/mbedtls/ssl_internal.h b/include/mbedtls/ssl_internal.h
index 00b941dc6..43443bf59 100644
--- a/include/mbedtls/ssl_internal.h
+++ b/include/mbedtls/ssl_internal.h
@@ -962,12 +962,22 @@ int mbedtls_ssl_check_sig_hash( const mbedtls_ssl_context *ssl,
 
 static inline int mbedtls_ssl_get_minor_ver( mbedtls_ssl_context const *ssl )
 {
+#if !defined(MBEDTLS_SSL_CONF_FIXED_MINOR_VER)
     return( ssl->minor_ver );
+#else /* !MBEDTLS_SSL_CONF_FIXED_MINOR_VER */
+    ((void) ssl);
+    return( MBEDTLS_SSL_CONF_FIXED_MINOR_VER );
+#endif /* MBEDTLS_SSL_CONF_FIXED_MINOR_VER */
 }
 
 static inline int mbedtls_ssl_get_major_ver( mbedtls_ssl_context const *ssl )
 {
+#if !defined(MBEDTLS_SSL_CONF_FIXED_MAJOR_VER)
     return( ssl->major_ver );
+#else /* !MBEDTLS_SSL_CONF_FIXED_MAJOR_VER */
+    ((void) ssl);
+    return( MBEDTLS_SSL_CONF_FIXED_MAJOR_VER );
+#endif /* MBEDTLS_SSL_CONF_FIXED_MAJOR_VER */
 }
 
 #if defined(MBEDTLS_X509_CRT_PARSE_C)
diff --git a/library/ssl_cli.c b/library/ssl_cli.c
index d69bd1ced..c7a18f58b 100644
--- a/library/ssl_cli.c
+++ b/library/ssl_cli.c
@@ -850,8 +850,12 @@ static int ssl_write_client_hello( mbedtls_ssl_context *ssl )
 
     if( mbedtls_ssl_get_renego_status( ssl ) == MBEDTLS_SSL_INITIAL_HANDSHAKE )
     {
+#if !defined(MBEDTLS_SSL_CONF_FIXED_MAJOR_VER)
         ssl->major_ver = mbedtls_ssl_conf_get_min_major_ver( ssl->conf );
+#endif /* !MBEDTLS_SSL_CONF_FIXED_MAJOR_VER */
+#if !defined(MBEDTLS_SSL_CONF_FIXED_MINOR_VER)
         ssl->minor_ver = mbedtls_ssl_conf_get_min_minor_ver( ssl->conf );
+#endif /* !MBEDTLS_SSL_CONF_FIXED_MINOR_VER */
     }
 
     if( mbedtls_ssl_conf_get_max_major_ver( ssl->conf ) == 0 )
@@ -1743,8 +1747,13 @@ static int ssl_parse_server_hello( mbedtls_ssl_context *ssl )
             return( MBEDTLS_ERR_SSL_BAD_HS_PROTOCOL_VERSION );
         }
 
+#if !defined(MBEDTLS_SSL_CONF_FIXED_MINOR_VER)
         ssl->minor_ver = minor_ver;
+#endif /* !MBEDTLS_SSL_CONF_FIXED_MINOR_VER */
+
+#if !defined(MBEDTLS_SSL_CONF_FIXED_MAJOR_VER)
         ssl->major_ver = major_ver;
+#endif /* !MBEDTLS_SSL_CONF_FIXED_MAJOR_VER */
     }
 
     MBEDTLS_SSL_DEBUG_MSG( 3, ( "server hello, current time: %lu",
diff --git a/library/ssl_srv.c b/library/ssl_srv.c
index 84cb04b4a..87fe4c973 100644
--- a/library/ssl_srv.c
+++ b/library/ssl_srv.c
@@ -1654,8 +1654,12 @@ read_record_header:
         else if( minor_ver > mbedtls_ssl_conf_get_max_minor_ver( ssl->conf ) )
             minor_ver = mbedtls_ssl_conf_get_max_minor_ver( ssl->conf );
 
+#if !defined(MBEDTLS_SSL_CONF_FIXED_MAJOR_VER)
         ssl->major_ver = major_ver;
+#endif /* MBEDTLS_SSL_CONF_FIXED_MAJOR_VER */
+#if !defined(MBEDTLS_SSL_CONF_FIXED_MINOR_VER)
         ssl->minor_ver = minor_ver;
+#endif /* MBEDTLS_SSL_CONF_FIXED_MINOR_VER */
     }
 
     /*