commit 26f982f50e6a7f55e41d2e7e5dec17a8e7162839
author Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com> Tue May 21 11:01:32 2019 +0200
committer Jarno Lamsa <jarno.lamsa@arm.com> Fri Aug 23 12:48:41 2019 +0300
tree 6c09496712790231061c7cb85c0802e13b5378f6
parent a7c376576058ae843b03e6b33d185849a8d80554

Improve save API by always updating olen

This allows callers to discover what an appropriate size is. Otherwise they'd
have to either try repeatedly, or allocate an overly large buffer (or some
combination of those).

Adapt documentation an example usage in ssl_client2.

programs/ssl/ssl_client2.c

diff --git a/programs/ssl/ssl_client2.c b/programs/ssl/ssl_client2.c
index 36b78e5..317fea3 100644
--- a/programs/ssl/ssl_client2.c
+++ b/programs/ssl/ssl_client2.c
@@ -38,6 +38,8 @@
 #define mbedtls_calloc     calloc
 #define mbedtls_free       free
 #define mbedtls_exit            exit
+#define mbedtls_calloc      calloc
+#define mbedtls_free        free
 #define MBEDTLS_EXIT_SUCCESS    EXIT_SUCCESS
 #define MBEDTLS_EXIT_FAILURE    EXIT_FAILURE
 #endif
@@ -1052,8 +1054,8 @@
     mbedtls_ssl_context ssl;
     mbedtls_ssl_config conf;
     mbedtls_ssl_session saved_session;
-    unsigned char session_data[MBEDTLS_SSL_MAX_CONTENT_LEN];
-    size_t session_data_len;
+    unsigned char *session_data = NULL;
+    size_t session_data_len = 0;
 #if defined(MBEDTLS_TIMING_C)
     mbedtls_timing_delay_context timer;
 #endif
@@ -2456,8 +2458,25 @@
 
         if( opt.reco_mode == 1 )
         {
+            /* free any previously saved data */
+            mbedtls_free( session_data );
+            session_data = NULL;
+
+            /* get size of the buffer needed */
+            mbedtls_ssl_session_save( mbedtls_ssl_get_session_pointer( &ssl ),
+                                      NULL, 0, &session_data_len );
+            session_data = mbedtls_calloc( 1, session_data_len );
+            if( session_data == NULL )
+            {
+                mbedtls_printf( " failed\n  ! alloc %u bytes for session data\n",
+                                (unsigned) session_data_len );
+                ret = MBEDTLS_ERR_SSL_ALLOC_FAILED;
+                goto exit;
+            }
+
+            /* actually save session data */
             if( ( ret = mbedtls_ssl_session_save( mbedtls_ssl_get_session_pointer( &ssl ),
-                                                  session_data, sizeof( session_data ),
+                                                  session_data, session_data_len,
                                                   &session_data_len ) ) != 0 )
             {
                 mbedtls_printf( " failed\n  ! mbedtls_ssl_session_saved returned -0x%04x\n\n",
@@ -2476,6 +2495,12 @@
         }
 
         mbedtls_printf( " ok\n" );
+
+        if( opt.reco_mode == 1 )
+        {
+            mbedtls_printf( "    [ Saved %u bytes of session data]\n",
+                            (unsigned) session_data_len );
+        }
     }
 
 #if defined(MBEDTLS_X509_CRT_PARSE_C)
@@ -2999,6 +3024,7 @@
     mbedtls_ssl_config_free( &conf );
     mbedtls_ctr_drbg_free( &ctr_drbg );
     mbedtls_entropy_free( &entropy );
+    mbedtls_free( session_data );
 
 #if defined(MBEDTLS_KEY_EXCHANGE__SOME__PSK_ENABLED) && \
     defined(MBEDTLS_USE_PSA_CRYPTO)