-#define SSL3_RT_MAX_COMPRESSED_LENGTH (1024+SSL3_RT_MAX_PLAIN_LENGTH)
-#define SSL3_RT_MAX_ENCRYPTED_LENGTH (1024+SSL3_RT_MAX_COMPRESSED_LENGTH)
-#define SSL3_RT_MAX_PACKET_SIZE (SSL3_RT_MAX_ENCRYPTED_LENGTH+SSL3_RT_HEADER_LENGTH)
-#define SSL3_RT_MAX_DATA_SIZE (1024*1024)
+/* Maximum compression overhead: defined by SSL/TLS standards */
+#define SSL3_RT_MAX_COMPRESSED_OVERHEAD 1024
+
+/* The standards give a maximum encryption overhead of 1024 bytes.
+ * In practice the value is lower than this. The overhead is the maximum
+ * number of padding bytes (256) plus the mac size.
+ */
+#define SSL3_RT_MAX_ENCRYPTED_OVERHEAD (256 + SSL3_RT_MAX_MD_SIZE)
+
+/* OpenSSL currently only uses a padding length of at most one block so
+ * the send overhead is smaller.
+ */
+
+#define SSL3_RT_SEND_MAX_ENCRYPTED_OVERHEAD \
+ (SSL_RT_MAX_CIPHER_BLOCK_SIZE + SSL3_RT_MAX_MD_SIZE)
+
+/* If compression isn't used don't include the compression overhead */
+
+#ifdef OPENSSL_NO_COMP
+#define SSL3_RT_MAX_COMPRESSED_LENGTH SSL3_RT_MAX_PLAIN_LENGTH
+#else
+#define SSL3_RT_MAX_COMPRESSED_LENGTH \
+ (SSL3_RT_MAX_PLAIN_LENGTH+SSL3_RT_MAX_COMPRESSED_OVERHEAD)
+#endif
+#define SSL3_RT_MAX_ENCRYPTED_LENGTH \
+ (SSL3_RT_MAX_ENCRYPTED_OVERHEAD+SSL3_RT_MAX_COMPRESSED_LENGTH)
+#define SSL3_RT_MAX_PACKET_SIZE \
+ (SSL3_RT_MAX_ENCRYPTED_LENGTH+SSL3_RT_HEADER_LENGTH)