I'm stuck and looking for some hints/help. I have two MTAs (let's call them M1 and S8), both built with OpenSSL 1.1.1g. The problem is M1 cannot establish a TLSv1.3 connection with S8. Using other MTAs/sites/protocols/tools works just fine, e.g., M1 can send mail to google using TLSv1.3, and S8 can send mail to M1. Replacing the server or client with openssl s_client/s_server also works. I've added some TLS callbacks to S8 which I found in s_cb.c, but all I get at the end is "SSL_accept:error in TLSv1.3 early data" (see "full" trace below for the steps leading to this). Unfortunately I cannot find a way to figure out more details or what kind of error that is. Any hints how to determine (and fix?) the problem? S8 server side: info_callback where=0x10, ret=1 info_callback where=0x2001, ret=1 SSL_accept:before SSL initialization ssl_msg_cb, writep=0, version=0, len=5, ct=256 ssl_msg_cb, before SSL initialization info_callback where=0x2001, ret=1 SSL_accept:before SSL initialization ssl_msg_cb, writep=0, version=772, len=512, ct=22 ssl_msg_cb, SSLv3/TLS read client hello info_callback where=0x2001, ret=1 SSL_accept:SSLv3/TLS read client hello ssl_msg_cb, writep=1, version=0, len=5, ct=256 ssl_msg_cb, SSLv3/TLS write server hello ssl_msg_cb, writep=1, version=772, len=88, ct=22 ssl_msg_cb, SSLv3/TLS write server hello info_callback where=0x2001, ret=1 SSL_accept:SSLv3/TLS write server hello ssl_msg_cb, writep=1, version=0, len=5, ct=256 ssl_msg_cb, SSLv3/TLS write change cipher spec ssl_msg_cb, writep=1, version=772, len=1, ct=20 ssl_msg_cb, SSLv3/TLS write change cipher spec info_callback where=0x2001, ret=1 SSL_accept:SSLv3/TLS write change cipher spec info_callback where=0x2001, ret=1 SSL_accept:TLSv1.3 early data info_callback where=0x2002, ret=-1 SSL_accept:error in TLSv1.3 early data M1 client side: apps_ssl_info_cb, where=10, ret=1 apps_ssl_info_cb, SSL_connect=before SSL initialization ssl_msg_cb, writep=1, version=0, len=5, ct=100 ssl_msg_cb, SSLv3/TLS write client hello ssl_msg_cb, writep=1, version=772, len=512, ct=16 ssl_msg_cb, SSLv3/TLS write client hello apps_ssl_info_cb, SSL_connect=SSLv3/TLS write client hello ssl_msg_cb, writep=0, version=0, len=5, ct=100 ssl_msg_cb, SSLv3/TLS write client hello apps_ssl_info_cb, SSL_connect=SSLv3/TLS write client hello ssl_msg_cb, writep=0, version=772, len=88, ct=16 ssl_msg_cb, SSLv3/TLS read server hello apps_ssl_info_cb, SSL_connect=SSLv3/TLS read server hello ssl_msg_cb, writep=1, version=0, len=5, ct=100 ssl_msg_cb, SSLv3/TLS write change cipher spec ssl_msg_cb, writep=1, version=772, len=1, ct=14 ssl_msg_cb, SSLv3/TLS write change cipher spec apps_ssl_info_cb, SSL_connect=SSLv3/TLS write change cipher spec ssl_msg_cb, writep=1, version=0, len=5, ct=100 ssl_msg_cb, SSLv3/TLS write client hello ssl_msg_cb, writep=1, version=772, len=512, ct=16 ssl_msg_cb, SSLv3/TLS write client hello apps_ssl_info_cb, SSL_connect=SSLv3/TLS write client hello ssl_msg_cb, writep=0, version=0, len=5, ct=100 ssl_msg_cb, SSLv3/TLS write client hello and here it hangs until timeout.
