Use record length from record structure when fetching content in TLS

library/ssl_tls.c

diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index 278027a..3a6efef 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -6095,8 +6095,7 @@
         /*
          * Fetch record contents from underlying transport.
          */
-        ret = mbedtls_ssl_fetch_input( ssl,
-                              mbedtls_ssl_in_hdr_len( ssl ) + ssl->in_msglen );
+        ret = mbedtls_ssl_fetch_input( ssl, rec.buf_len );
         if( ret != 0 )
         {
             MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_fetch_input", ret );