From fd5c185ed656cbf4e1668973c95c67bfda02e1fe Mon Sep 17 00:00:00 2001
From: Hanno Becker <hanno.becker@arm.com>
Date: Mon, 13 May 2019 12:52:57 +0100
Subject: [PATCH] Use uint16_t to store key usage field in X.509 CRT

Also, reorder the fields to avoid padding, thereby reducing the size of
mbedtls_x509_crt_frame by 2 Bytes.
---
 include/mbedtls/x509_crt.h | 8 ++++----
 library/x509_crt.c         | 6 +++---
 2 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/include/mbedtls/x509_crt.h b/include/mbedtls/x509_crt.h
index 26f3a622c..47b29def1 100644
--- a/include/mbedtls/x509_crt.h
+++ b/include/mbedtls/x509_crt.h
@@ -63,13 +63,13 @@ typedef struct mbedtls_x509_crt_frame
     uint8_t ns_cert_type;                   /**< Optional Netscape certificate type extension value:
                                              *   See the values in x509.h                                       */
 
-    unsigned int key_usage;                 /**< Optional key usage extension value: See the values in x509.h   */
-    uint32_t ext_types;                     /**< Bitfield indicating which extensions are present.
-                                             *   See the values in x509.h.                                      */
-
     mbedtls_md_type_t sig_md;               /**< The hash algorithm used to hash CRT before signing.            */
     mbedtls_pk_type_t sig_pk;               /**< The signature algorithm used to sign the CRT hash.             */
 
+    uint16_t key_usage;                     /**< Optional key usage extension value: See the values in x509.h   */
+    uint32_t ext_types;                     /**< Bitfield indicating which extensions are present.
+                                             *   See the values in x509.h.                                      */
+
     mbedtls_x509_time valid_from;           /**< The start time of certificate validity.                        */
     mbedtls_x509_time valid_to;             /**< The end time of certificate validity.                          */
 
diff --git a/library/x509_crt.c b/library/x509_crt.c
index ffd3d9bc4..4e5f6f50f 100644
--- a/library/x509_crt.c
+++ b/library/x509_crt.c
@@ -781,7 +781,7 @@ static int x509_get_ns_cert_type( unsigned char **p,
 
 static int x509_get_key_usage( unsigned char **p,
                                const unsigned char *end,
-                               unsigned int *key_usage)
+                               uint16_t *key_usage)
 {
     int ret;
     size_t i;
@@ -795,9 +795,9 @@ static int x509_get_key_usage( unsigned char **p,
 
     /* Get actual bitstring */
     *key_usage = 0;
-    for( i = 0; i < bs.len && i < sizeof( unsigned int ); i++ )
+    for( i = 0; i < bs.len && i < sizeof( *key_usage ); i++ )
     {
-        *key_usage |= (unsigned int) bs.p[i] << (8*i);
+        *key_usage |= (uint16_t) bs.p[i] << ( 8*i );
     }
 
     return( 0 );