[gnutls-devel] GnuTLS | Cannot connect to pop.verizon.net:995 (#997)

[Development of GNU's TLS library]

rrivers2 commented:


[allow_zero_length_session_tickets.patch](/uploads/26bec94f704ed4f5530703e377d7232b/allow_zero_length_session_tickets.patch)

Daiki,

Will Ubuntu upgrade the version of GnuTLS in 18.04 from 3.5 to 3.6?  If not, I attached a first cut at a patch to allow zero length sessions tickets returned by a server.  It is based on the latest source code from Ubuntu 18.04 in the gnutls28-3.5.18 package.  After the patch is applied gnutls-cli will connect to pop.verizon.net:995 successfully, display the banner and prompt for input:
```
- Handshake was completed

- Simple Client Mode:

+OK Hello from jpop-0.1
```

More testing is needed to make sure that setting priv->session_ticket to NULL and priv->session_ticket_len to 0 doesn't break the rest of the code.

Testing with the current version of OpenSSL on Ubuntu 18.04.4 (1.1.1-1ubuntu2.1~18.04.5) showed that it is able to handle zero length session tickets:

```
openssl s_client -msg -tls1_2 -connect pop.verizon.net:995

<<< TLS 1.2, Handshake [length 000a], NewSessionTicket
    04 00 00 06 00 00 00 3c 00 00
```

It displays the banner and waits for input.

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