Merge pull request #4918 from yuhaoth/pr/add-send-alert-message-macro

Add send alert message macro

include/mbedtls/ssl.h

@@ -1526,6 +1526,19 @@ struct mbedtls_ssl_context
     int MBEDTLS_PRIVATE(keep_current_message);   /*!< drop or reuse current message
                                      on next call to record layer? */
 
+    /* The following three variables indicate if and, if yes,
+     * what kind of alert is pending to be sent.
+     */
+    unsigned char MBEDTLS_PRIVATE(send_alert);   /*!< Determines if a fatal alert
+                                                should be sent. Values:
+                                                - \c 0 , no alert is to be sent.
+                                                - \c 1 , alert is to be sent. */
+    unsigned char MBEDTLS_PRIVATE(alert_type);   /*!< Type of alert if send_alert
+                                                 != 0 */
+    int MBEDTLS_PRIVATE(alert_reason);           /*!< The error code to be returned
+                                                 to the user once the fatal alert
+                                                 has been sent. */
+
 #if defined(MBEDTLS_SSL_PROTO_DTLS)
     uint8_t MBEDTLS_PRIVATE(disable_datagram_packing);  /*!< Disable packing multiple records
                                         *   within a single datagram.  */

library/ssl_misc.h

@@ -1342,6 +1342,22 @@ void mbedtls_ssl_update_in_pointers( mbedtls_ssl_context *ssl );
 
 int mbedtls_ssl_session_reset_int( mbedtls_ssl_context *ssl, int partial );
 
+/*
+ * Send pending alert
+ */
+int mbedtls_ssl_handle_pending_alert( mbedtls_ssl_context *ssl );
+
+/*
+ * Set pending fatal alert flag.
+ */
+void mbedtls_ssl_pend_fatal_alert( mbedtls_ssl_context *ssl,
+                                   unsigned char alert_type,
+                                   int alert_reason );
+
+/* Alias of mbedtls_ssl_pend_fatal_alert */
+#define MBEDTLS_SSL_PEND_FATAL_ALERT( type, user_return_value )         \
+            mbedtls_ssl_pend_fatal_alert( ssl, type, user_return_value )
+
 #if defined(MBEDTLS_SSL_DTLS_ANTI_REPLAY)
 void mbedtls_ssl_dtls_replay_reset( mbedtls_ssl_context *ssl );
 #endif

library/ssl_msg.c

@@ -5639,4 +5639,48 @@ void mbedtls_ssl_read_version( int *major, int *minor, int transport,
     }
 }
 
+/*
+ * Send pending fatal alert.
+ * 0,   No alert message.
+ * !0,  if mbedtls_ssl_send_alert_message() returned in error, the error code it
+ *      returned, ssl->alert_reason otherwise.
+ */
+int mbedtls_ssl_handle_pending_alert( mbedtls_ssl_context *ssl )
+{
+    int ret;
+
+    /* No pending alert, return success*/
+    if( ssl->send_alert == 0 )
+        return( 0 );
+
+    ret = mbedtls_ssl_send_alert_message( ssl,
+                                MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                ssl->alert_type );
+
+    /* If mbedtls_ssl_send_alert_message() returned with MBEDTLS_ERR_SSL_WANT_WRITE,
+     * do not clear the alert to be able to send it later.
+     */
+    if( ret != MBEDTLS_ERR_SSL_WANT_WRITE )
+    {
+        ssl->send_alert = 0;
+    }
+
+    if( ret != 0 )
+        return( ret );
+
+    return( ssl->alert_reason );
+}
+
+/*
+ * Set pending fatal alert flag.
+ */
+void mbedtls_ssl_pend_fatal_alert( mbedtls_ssl_context *ssl,
+                                   unsigned char alert_type,
+                                   int alert_reason )
+{
+    ssl->send_alert = 1;
+    ssl->alert_type = alert_type;
+    ssl->alert_reason = alert_reason;
+}
+
 #endif /* MBEDTLS_SSL_TLS_C */

library/ssl_tls.c

@@ -5170,6 +5170,10 @@ int mbedtls_ssl_handshake_step( mbedtls_ssl_context *ssl )
     if( ret != 0 )
         return( ret );
 
+    ret = mbedtls_ssl_handle_pending_alert( ssl );
+    if( ret != 0 )
+        goto cleanup;
+
 #if defined(MBEDTLS_SSL_CLI_C)
     if( ssl->conf->endpoint == MBEDTLS_SSL_IS_CLIENT )
     {
@@ -5199,6 +5203,19 @@ int mbedtls_ssl_handshake_step( mbedtls_ssl_context *ssl )
     }
 #endif
 
+    if( ret != 0 )
+    {
+        /* handshake_step return error. And it is same
+         * with alert_reason.
+         */
+        if( ssl->send_alert )
+        {
+            ret = mbedtls_ssl_handle_pending_alert( ssl );
+            goto cleanup;
+        }
+    }
+
+cleanup:
     return( ret );
 }