[InterNetNews/inn] 8360cb: nnrpd: Discards incoming data after a timeout

[Julien ÉLIE]

  Branch: refs/heads/2.6
  Home:   https://github.com/InterNetNews/inn
  Commit: 8360cb5f3fc9fd9444316e58db5648760cbbcde0
      https://github.com/InterNetNews/inn/commit/8360cb5f3fc9fd9444316e58db5648760cbbcde0
  Author: Julien ÉLIE <Julien-Elie at users.noreply.github.com>
  Date:   2021-11-20 (Sat, 20 Nov 2021)

  Changed paths:
    M doc/pod/news.pod
    M nnrpd/article.c
    M nnrpd/line.c
    M nnrpd/nnrpd.c
    M scripts/innreport_inn.pm

  Log Message:
  -----------
  nnrpd: Discards incoming data after a timeout

When a timeout occurs during a TLS session, nnrpd sent the close_notify
shutdown alert, and then tried to SSL_read() incoming data and act on
these data.  It led to inflate() and sasl_decode() errors.

The right behaviour is to discard these data because we do not expect them
from a news client at that stage of the connection.

Also, there is no need in calling SSL_shutdown() twice (a unidirectional
shutdown is allowed per OpenSSL documentation), so don't call it and just
discard the data.

After SSL_ERROR_ZERO_RETURN, SSL_shutdown() should be called, but never
after SSL_ERROR_SYSCALL or SSL_ERROR_SSL.

Finally, this commit also teaches innreport not to report "can't read"
errors as unknown log lines.  When that error occurs, another log line is
usually present with the related error.