commit 434c87301da38fd685ad7b9541c69ab524d175af
author Maxim Dounin <mdounin@mdounin.ru> Wed Sep 16 18:26:22 2020 +0300
committer Maxim Dounin <mdounin@mdounin.ru> Wed Sep 16 18:26:22 2020 +0300
tree fa1e3d50fd8275d53fb98120e913946184571973
parent 576cd9f63fe16215e0aad5afe645fccfaca420cf

SSL: workaround for incorrect SSL_write() errors in OpenSSL 1.1.1.

OpenSSL 1.1.1 fails to return SSL_ERROR_SYSCALL if an error happens
during SSL_write() after close_notify alert from the peer, and returns
SSL_ERROR_ZERO_RETURN instead.  Broken by this commit, which removes
the "i == 0" check around the SSL_RECEIVED_SHUTDOWN one:

https://git.openssl.org/?p=openssl.git;a=commitdiff;h=8051ab2

In particular, if a client closed the connection without reading
the response but with properly sent close_notify alert, this resulted in
unexpected "SSL_write() failed while ..." critical log message instead
of correct "SSL_write() failed (32: Broken pipe)" at the info level.

Since SSL_ERROR_ZERO_RETURN cannot be legitimately returned after
SSL_write(), the fix is to convert all SSL_ERROR_ZERO_RETURN errors
after SSL_write() to SSL_ERROR_SYSCALL.