diff --git a/include/mbedtls/ssl_internal.h b/include/mbedtls/ssl_internal.h
index 310e283..122c1ee 100644
--- a/include/mbedtls/ssl_internal.h
+++ b/include/mbedtls/ssl_internal.h
@@ -42,6 +42,116 @@
 #include "sha512.h"
 #endif
 
+#if defined(_MSC_VER) && !defined(inline)
+#define inline _inline
+#else
+#if defined(__ARMCC_VERSION) && !defined(inline)
+#define inline __inline
+#endif /* __ARMCC_VERSION */
+#endif /*_MSC_VER */
+
+/* Determine minimum supported version */
+#define MBEDTLS_SSL_MIN_MAJOR_VERSION           MBEDTLS_SSL_MAJOR_VERSION_3
+
+#if defined(MBEDTLS_SSL_PROTO_SSL3)
+#define MBEDTLS_SSL_MIN_MINOR_VERSION           MBEDTLS_SSL_MINOR_VERSION_0
+#else
+#if defined(MBEDTLS_SSL_PROTO_TLS1)
+#define MBEDTLS_SSL_MIN_MINOR_VERSION           MBEDTLS_SSL_MINOR_VERSION_1
+#else
+#if defined(MBEDTLS_SSL_PROTO_TLS1_1)
+#define MBEDTLS_SSL_MIN_MINOR_VERSION           MBEDTLS_SSL_MINOR_VERSION_2
+#else
+#if defined(MBEDTLS_SSL_PROTO_TLS1_2)
+#define MBEDTLS_SSL_MIN_MINOR_VERSION           MBEDTLS_SSL_MINOR_VERSION_3
+#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
+#endif /* MBEDTLS_SSL_PROTO_TLS1_1 */
+#endif /* MBEDTLS_SSL_PROTO_TLS1   */
+#endif /* MBEDTLS_SSL_PROTO_SSL3   */
+
+/* Determine maximum supported version */
+#define MBEDTLS_SSL_MAX_MAJOR_VERSION           MBEDTLS_SSL_MAJOR_VERSION_3
+
+#if defined(MBEDTLS_SSL_PROTO_TLS1_2)
+#define MBEDTLS_SSL_MAX_MINOR_VERSION           MBEDTLS_SSL_MINOR_VERSION_3
+#else
+#if defined(MBEDTLS_SSL_PROTO_TLS1_1)
+#define MBEDTLS_SSL_MAX_MINOR_VERSION           MBEDTLS_SSL_MINOR_VERSION_2
+#else
+#if defined(MBEDTLS_SSL_PROTO_TLS1)
+#define MBEDTLS_SSL_MAX_MINOR_VERSION           MBEDTLS_SSL_MINOR_VERSION_1
+#else
+#if defined(MBEDTLS_SSL_PROTO_SSL3)
+#define MBEDTLS_SSL_MAX_MINOR_VERSION           MBEDTLS_SSL_MINOR_VERSION_0
+#endif /* MBEDTLS_SSL_PROTO_SSL3   */
+#endif /* MBEDTLS_SSL_PROTO_TLS1   */
+#endif /* MBEDTLS_SSL_PROTO_TLS1_1 */
+#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
+
+#define MBEDTLS_SSL_INITIAL_HANDSHAKE           0
+#define MBEDTLS_SSL_RENEGOTIATION_IN_PROGRESS   1   /* In progress */
+#define MBEDTLS_SSL_RENEGOTIATION_DONE          2   /* Done or aborted */
+#define MBEDTLS_SSL_RENEGOTIATION_PENDING       3   /* Requested (server only) */
+
+/*
+ * DTLS retransmission states, see RFC 6347 4.2.4
+ *
+ * The SENDING state is merged in PREPARING for initial sends,
+ * but is distinct for resends.
+ *
+ * Note: initial state is wrong for server, but is not used anyway.
+ */
+#define MBEDTLS_SSL_RETRANS_PREPARING       0
+#define MBEDTLS_SSL_RETRANS_SENDING         1
+#define MBEDTLS_SSL_RETRANS_WAITING         2
+#define MBEDTLS_SSL_RETRANS_FINISHED        3
+
+/*
+ * Allow extra bytes for record, authentication and encryption overhead:
+ * counter (8) + header (5) + IV(16) + MAC (16-48) + padding (0-256)
+ * and allow for a maximum of 1024 of compression expansion if
+ * enabled.
+ */
+#if defined(MBEDTLS_ZLIB_SUPPORT)
+#define MBEDTLS_SSL_COMPRESSION_ADD          1024
+#else
+#define MBEDTLS_SSL_COMPRESSION_ADD             0
+#endif
+
+#if defined(MBEDTLS_ARC4_C) || defined(MBEDTLS_CIPHER_MODE_CBC)
+/* Ciphersuites using HMAC */
+#if defined(MBEDTLS_SHA512_C)
+#define MBEDTLS_SSL_MAC_ADD                 48  /* SHA-384 used for HMAC */
+#elif defined(MBEDTLS_SHA256_C)
+#define MBEDTLS_SSL_MAC_ADD                 32  /* SHA-256 used for HMAC */
+#else
+#define MBEDTLS_SSL_MAC_ADD                 20  /* SHA-1   used for HMAC */
+#endif
+#else
+/* AEAD ciphersuites: GCM and CCM use a 128 bits tag */
+#define MBEDTLS_SSL_MAC_ADD                 16
+#endif
+
+#if defined(MBEDTLS_CIPHER_MODE_CBC)
+#define MBEDTLS_SSL_PADDING_ADD            256
+#else
+#define MBEDTLS_SSL_PADDING_ADD              0
+#endif
+
+#define MBEDTLS_SSL_BUFFER_LEN  ( MBEDTLS_SSL_MAX_CONTENT_LEN               \
+                        + MBEDTLS_SSL_COMPRESSION_ADD               \
+                        + 29 /* counter + header + IV */    \
+                        + MBEDTLS_SSL_MAC_ADD                       \
+                        + MBEDTLS_SSL_PADDING_ADD                   \
+                        )
+
+/*
+ * TLS extension flags (for extensions with outgoing ServerHello content
+ * that need it (e.g. for RENEGOTIATION_INFO the server already knows because
+ * of state of the renegotiation flag, so no indicator is required)
+ */
+#define MBEDTLS_TLS_EXT_SUPPORTED_POINT_FORMATS_PRESENT (1 << 0)
+
 #ifdef __cplusplus
 extern "C" {
 #endif