commit 66dbf9118e8db8218e1ecd23cf41930dfbea5ee8
author Ronald Cron <ronald.cron@arm.com> Wed Feb 02 15:33:46 2022 +0100
committer Ronald Cron <ronald.cron@arm.com> Wed Mar 09 07:51:52 2022 +0100
tree 5db5af8fdfa367b5e3ce3dacf2e4f81cbf27b885
parent 9df7c80c786c3d70550b96ad57efd33d864bf8e0

TLS 1.3: Do not send handshake data in handshake step handlers

Send data (call to mbedtls_ssl_flush_output()) only from
the loop over the handshake steps. That way, we do not
have to take care of the partial writings (MBEDTLS_ERR_SSL_WANT_WRITE
error code) on the network in handshake step handlers.

Signed-off-by: Ronald Cron <ronald.cron@arm.com>

library/ssl_tls13_generic.c

diff --git a/library/ssl_tls13_generic.c b/library/ssl_tls13_generic.c
index 4fee3b0..a54207c 100644
--- a/library/ssl_tls13_generic.c
+++ b/library/ssl_tls13_generic.c
@@ -103,7 +103,7 @@
     /* Add reserved 4 bytes for handshake header */
     msg_with_header_len = msg_len + 4;
     ssl->out_msglen = msg_with_header_len;
-    MBEDTLS_SSL_PROC_CHK( mbedtls_ssl_write_handshake_msg_ext( ssl, 0 ) );
+    MBEDTLS_SSL_PROC_CHK( mbedtls_ssl_write_handshake_msg_ext( ssl, 0, 0 ) );
 
 cleanup:
     return( ret );
@@ -1483,7 +1483,6 @@
     MBEDTLS_SSL_PROC_CHK( ssl_tls13_finalize_finished_message( ssl ) );
     MBEDTLS_SSL_PROC_CHK( mbedtls_ssl_tls13_finish_handshake_msg( ssl,
                                               buf_len, msg_len ) );
-    MBEDTLS_SSL_PROC_CHK( mbedtls_ssl_flush_output( ssl ) );
 
 cleanup:
 
@@ -1564,8 +1563,6 @@
 
     MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> write change cipher spec" ) );
 
-    MBEDTLS_SSL_PROC_CHK( mbedtls_ssl_flush_output( ssl ) );
-
     /* Write CCS message */
     MBEDTLS_SSL_PROC_CHK( ssl_tls13_write_change_cipher_spec_body(
                               ssl, ssl->out_msg,
@@ -1578,7 +1575,7 @@
     MBEDTLS_SSL_PROC_CHK( ssl_tls13_finalize_change_cipher_spec( ssl ) );
 
     /* Dispatch message */
-    MBEDTLS_SSL_PROC_CHK( mbedtls_ssl_write_record( ssl, 1 ) );
+    MBEDTLS_SSL_PROC_CHK( mbedtls_ssl_write_record( ssl, 0 ) );
 
 cleanup: