From 81bd97149fb12662a3fef1ced5950e735012f682 Mon Sep 17 00:00:00 2001
From: Hanno Becker <hanno.becker@arm.com>
Date: Tue, 9 Apr 2019 15:12:41 +0100
Subject: [PATCH] Add new configuration option controlling CID extension

---
 include/mbedtls/config.h | 37 +++++++++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)

diff --git a/include/mbedtls/config.h b/include/mbedtls/config.h
index 654f9725e..ccd800460 100644
--- a/include/mbedtls/config.h
+++ b/include/mbedtls/config.h
@@ -1269,6 +1269,29 @@
  */
 #define MBEDTLS_SSL_ALL_ALERT_MESSAGES
 
+/**
+ * \def MBEDTLS_SSL_CID
+ *
+ * Enable support for the DTLS Connection ID extension which
+ * allows to identify DTLS connections across changes in the
+ * underlying transport.
+ *
+ * Setting this option enables the SSL APIs `mbedtls_ssl_set_cid()`
+ * and `mbedtls_ssl_get_peer_cid()`. See their documentation for more
+ * information.
+ *
+ * \warning The Connection ID extension is still in draft state.
+ *          We make no stability promises for the availability
+ *          or the shape of the API controlled by this option.
+ *
+ * See also MBEDTLS_SSL_CID_OUT_LEN_MAX and MBEDTLS_SSL_CID_IN_LEN_MAX.
+ *
+ * Requires: MBEDTLS_SSL_PROTO_DTLS
+ *
+ * Uncomment to enable the Connection ID extension.
+ */
+#define MBEDTLS_SSL_CID
+
 /**
  * \def MBEDTLS_SSL_ASYNC_PRIVATE
  *
@@ -3145,6 +3168,20 @@
  */
 //#define MBEDTLS_SSL_IN_CONTENT_LEN              16384
 
+/** \def MBEDTLS_SSL_CID_IN_LEN_MAX
+ *
+ * The maximum length of CIDs used for incoming DTLS messages.
+ *
+ */
+//#define MBEDTLS_SSL_CID_IN_LEN_MAX 32
+
+/** \def MBEDTLS_SSL_CID_OUT_LEN_MAX
+ *
+ * The maximum length of CIDs used for outgoing DTLS messages.
+ *
+ */
+//#define MBEDTLS_SSL_CID_OUT_LEN_MAX 32
+
 /** \def MBEDTLS_SSL_OUT_CONTENT_LEN
  *
  * Maximum length (in bytes) of outgoing plaintext fragments.