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_generic.c b/library/ssl_tls13_generic.c
index 38077dd..1a10e75 100644
--- a/library/ssl_tls13_generic.c
+++ b/library/ssl_tls13_generic.c
@@ -86,6 +86,61 @@
return ret;
}
+int mbedtls_ssl_tls13_is_supported_versions_ext_present_in_exts(
+ mbedtls_ssl_context *ssl,
+ const unsigned char *buf, const unsigned char *end,
+ const unsigned char **extension_data,
+ const unsigned char **extension_data_end)
+{
+ const unsigned char *p = buf;
+ size_t extensions_len;
+ const unsigned char *extensions_end;
+
+ *extension_data = NULL;
+ *extension_data_end = NULL;
+
+ /* Case of no extension */
+ if (p == end) {
+ return 0;
+ }
+
+ /* ...
+ * Extension extensions<x..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;
+ MBEDTLS_SSL_CHK_BUF_READ_PTR(p, extensions_end, extension_data_len);
+
+ if (extension_type == MBEDTLS_TLS_EXT_SUPPORTED_VERSIONS) {
+ *extension_data = p;
+ *extension_data_end = p + extension_data_len;
+ return 1;
+ }
+ p += extension_data_len;
+ }
+
+ return 0;
+}
+
#if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED)
/*
* STATE HANDLING: Read CertificateVerify