Fix max_fragment_length with DTLS
diff --git a/include/polarssl/ssl.h b/include/polarssl/ssl.h
index d2559ba..91f92f9 100644
--- a/include/polarssl/ssl.h
+++ b/include/polarssl/ssl.h
@@ -1946,6 +1946,12 @@
* \note When this function returns POLARSSL_ERR_NET_WANT_WRITE,
* it must be called later with the *same* arguments,
* until it returns a positive value.
+ *
+ * \note When DTLS is in use, and a maximum fragment length was
+ * either set with \c ssl_set_max_frag_len() or negotiated by
+ * the peer, len must not not be greater than the maximum
+ * fragment length, or POLARSSL_ERR_SSL_BAD_INPUT_DATA is
+ * returned.
*/
int ssl_write( ssl_context *ssl, const unsigned char *buf, size_t len );