commit 920db4581835b2144edaf188455b394e7e0927eb
author Yanray Wang <yanray.wang@arm.com> Tue Nov 14 17:20:16 2023 +0800
committer Yanray Wang <yanray.wang@arm.com> Wed Nov 22 10:33:11 2023 +0800
tree b7f1069e81dd825ab40b4905b2894a17b1022eb3
parent d4dc354185051e79b66118048ade3623779dc205

tls13: early_data: support to parse max_early_data_size ext

Signed-off-by: Yanray Wang <yanray.wang@arm.com>

library/ssl_tls13_client.c

diff --git a/library/ssl_tls13_client.c b/library/ssl_tls13_client.c
index 44814b9..361f0c0 100644
--- a/library/ssl_tls13_client.c
+++ b/library/ssl_tls13_client.c
@@ -2647,6 +2647,43 @@
 
 #if defined(MBEDTLS_SSL_SESSION_TICKETS)
 
+#if defined(MBEDTLS_SSL_EARLY_DATA)
+/* From RFC 8446 section 4.2.10
+ *
+ * struct {
+ *     select (Handshake.msg_type) {
+ *         case new_session_ticket:   uint32 max_early_data_size;
+ *         ...
+ *     };
+ * } EarlyDataIndication;
+ */
+MBEDTLS_CHECK_RETURN_CRITICAL
+static int ssl_tls13_parse_nst_early_data_ext(mbedtls_ssl_context *ssl,
+                                              const unsigned char *buf,
+                                              const unsigned char *end)
+{
+    MBEDTLS_SSL_CHK_BUF_READ_PTR(buf, end, 4);
+    if ((end - buf) != 4) {
+        MBEDTLS_SSL_PEND_FATAL_ALERT(
+            MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR,
+            MBEDTLS_ERR_SSL_DECODE_ERROR);
+        return MBEDTLS_ERR_SSL_DECODE_ERROR;
+    }
+
+    if (ssl->session != NULL) {
+        ssl->session->max_early_data_size = MBEDTLS_GET_UINT32_BE(buf, 0);
+        mbedtls_ssl_session_set_ticket_flags(
+            ssl->session, MBEDTLS_SSL_TLS1_3_TICKET_ALLOW_EARLY_DATA);
+        MBEDTLS_SSL_DEBUG_MSG(
+            3, ("received max_early_data_size: %u",
+                (unsigned int) ssl->session->max_early_data_size));
+        return 0;
+    }
+
+    return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
+}
+#endif /* MBEDTLS_SSL_EARLY_DATA */
+
 MBEDTLS_CHECK_RETURN_CRITICAL
 static int ssl_tls13_parse_new_session_ticket_exts(mbedtls_ssl_context *ssl,
                                                    const unsigned char *buf,
@@ -2680,15 +2717,11 @@
         switch (extension_type) {
 #if defined(MBEDTLS_SSL_EARLY_DATA)
             case MBEDTLS_TLS_EXT_EARLY_DATA:
-                if (extension_data_len != 4) {
-                    MBEDTLS_SSL_PEND_FATAL_ALERT(
-                        MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR,
-                        MBEDTLS_ERR_SSL_DECODE_ERROR);
-                    return MBEDTLS_ERR_SSL_DECODE_ERROR;
-                }
-                if (ssl->session != NULL) {
-                    ssl->session->ticket_flags |=
-                        MBEDTLS_SSL_TLS1_3_TICKET_ALLOW_EARLY_DATA;
+                ret = ssl_tls13_parse_nst_early_data_ext(
+                    ssl, p, p + extension_data_len);
+                if (ret != 0) {
+                    MBEDTLS_SSL_DEBUG_RET(
+                        1, "ssl_tls13_parse_max_early_data_size_ext", ret);
                 }
                 break;
 #endif /* MBEDTLS_SSL_EARLY_DATA */