tls13: Add function to search for a supported_versions extension
Move in a dedicated function the search for the
supported_versions extension in a list of
extensions, to be able to use it on server side
as well.
Signed-off-by: Ronald Cron <ronald.cron@arm.com>
diff --git a/library/ssl_tls13_client.c b/library/ssl_tls13_client.c
index d10fbeb..fedb2be 100644
--- a/library/ssl_tls13_client.c
+++ b/library/ssl_tls13_client.c
@@ -1324,8 +1324,8 @@
{
const unsigned char *p = buf;
size_t legacy_session_id_echo_len;
- size_t extensions_len;
- const unsigned char *extensions_end;
+ const unsigned char *supported_versions_ext;
+ const unsigned char *supported_versions_ext_end;
/*
* Check there is enough data to access the legacy_session_id_echo vector
@@ -1347,45 +1347,9 @@
MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, legacy_session_id_echo_len + 4);
p += legacy_session_id_echo_len + 4;
- /* Case of no extension */
- if (p == end) {
- return 0;
- }
-
- /* ...
- * Extension extensions<6..2^16-1>;
- * ...
- * struct {
- * ExtensionType extension_type; (2 bytes)
- * opaque extension_data<0..2^16-1>;
- * } Extension;
- */
- MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, 2);
- extensions_len = MBEDTLS_GET_UINT16_BE(p, 0);
- p += 2;
-
- /* Check extensions do not go beyond the buffer of data. */
- MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, extensions_len);
- extensions_end = p + extensions_len;
-
- while (p < extensions_end) {
- unsigned int extension_type;
- size_t extension_data_len;
-
- MBEDTLS_SSL_CHK_BUF_READ_PTR(p, extensions_end, 4);
- extension_type = MBEDTLS_GET_UINT16_BE(p, 0);
- extension_data_len = MBEDTLS_GET_UINT16_BE(p, 2);
- p += 4;
-
- if (extension_type == MBEDTLS_TLS_EXT_SUPPORTED_VERSIONS) {
- return 1;
- }
-
- MBEDTLS_SSL_CHK_BUF_READ_PTR(p, extensions_end, extension_data_len);
- p += extension_data_len;
- }
-
- return 0;
+ return mbedtls_ssl_tls13_is_supported_versions_ext_present_in_exts(
+ ssl, p, end,
+ &supported_versions_ext, &supported_versions_ext_end);
}
/* Returns a negative value on failure, and otherwise