TLS13_TBS_START_SIZE
#define TLS13_TBS_PREAMBLE_SIZE (TLS13_TBS_START_SIZE + 33 + 1)
memset(tls13tbs, 32, TLS13_TBS_START_SIZE);
strcpy((char *)tls13tbs + TLS13_TBS_START_SIZE, servercontext);
strcpy((char *)tls13tbs + TLS13_TBS_START_SIZE, clientcontext);