bug#40665: 28.0.50; tls hang on local ssl

[Robert Pluim]

>>>>> On Thu, 16 Apr 2020 14:06:30 +0000 (UTC), Derek Zhou <derek@3qin.us> said:

    Derek> I have a vps that have ssl cert from let's encrypt. If I run emacs on
    Derek> that machine and use eww to open the local url through proper DNS 
name,
    Derek> it hangs. This only happen with gnutls 3.6+ I believe. w3m works.

w3m uses OpenSSL rather than GnuTLS, I think.

    Derek> recipe:
    Derek> emacs -q
    Derek> M-x eww
    Derek> 
https://u15789687.ct.sendgrid.net/ls/click?upn=5u6PACFCQRlPqbnHSU4z2cQ21VoDRd3GIiP45VZkVss-3DZL1J_BeaubjMha5v6Ct1PCBdNXS7c-2B4F-2FiYml2FeMaPqPFw6mlPCBFCAdA-2BJhSopciFrXarTStvJH7F2cC8M4I5-2BSIuHrtbPlXdAWJ2PCGsvuTDU6kkpVZ5JAYurFBfbu8uG6PzR-2BqkNWc1EoW8kPIdIY9NymfSyaiKNcH-2F4DHCP9GFBvbUhtpcMZmq3z0U-2FWPsThxiaP-2BlzG2O8BI46NDehudn-2FKUS7g-2FjrNI0N1zBKjqzV6MI7ge8846jUqXY-2FUQ3jE

    Derek> This only happens when running on mail.3qin.us itself; from across 
the
    Derek> network it is ok. I believe it is timing related and worsen by very
    Derek> short network latency and small files.

Which version exactly of GnuTLS are you running? Is it possible for
you to do a local install of a newer version and try that with emacs?

Otherwise, maybe turning off TLS1.3 will help:

    (setq gnutls-algorithm-priority "NORMAL:-VERS-TLS1.3")

Another thing to try is setting 'gnutls-log-level' to progressively
higher values, to see if it resolves the timing issues.

Robert