[nginx] SSL: logging levels of "unsupported protocol", "version too low".

[Maxim Dounin]

details:   https://hg.nginx.org/nginx/rev/7c00d8dbdb3a
branches:  stable-1.14
changeset: 7413:7c00d8dbdb3a
user:      Maxim Dounin <mdounin at mdounin.ru>
date:      Mon Jul 16 17:47:18 2018 +0300
description:
SSL: logging levels of "unsupported protocol", "version too low".

Starting with OpenSSL 1.1.0, SSL_R_UNSUPPORTED_PROTOCOL instead of
SSL_R_UNKNOWN_PROTOCOL is reported when a protocol is disabled via
an SSL_OP_NO_* option.

Additionally, SSL_R_VERSION_TOO_LOW is reported when using MinProtocol
or when seclevel checks (as set by @SECLEVEL=n in the cipher string)
rejects a protocol, and this is what happens with SSLv3 and @SECLEVEL=1,
which is the default.

There is also the SSL_R_VERSION_TOO_HIGH error code, but it looks like
it is not possible to trigger it.

diffstat:

 src/event/ngx_event_openssl.c |  4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diffs (21 lines):

diff --git a/src/event/ngx_event_openssl.c b/src/event/ngx_event_openssl.c
--- a/src/event/ngx_event_openssl.c
+++ b/src/event/ngx_event_openssl.c
@@ -2080,6 +2080,7 @@ ngx_ssl_connection_error(ngx_connection_
             || n == SSL_R_UNEXPECTED_RECORD                          /*  245 */
             || n == SSL_R_UNKNOWN_ALERT_TYPE                         /*  246 */
             || n == SSL_R_UNKNOWN_PROTOCOL                           /*  252 */
+            || n == SSL_R_UNSUPPORTED_PROTOCOL                       /*  258 */
             || n == SSL_R_WRONG_VERSION_NUMBER                       /*  267 */
             || n == SSL_R_DECRYPTION_FAILED_OR_BAD_RECORD_MAC        /*  281 */
 #ifdef SSL_R_RENEGOTIATE_EXT_TOO_LONG
@@ -2096,6 +2097,9 @@ ngx_ssl_connection_error(ngx_connection_
 #ifdef SSL_R_INAPPROPRIATE_FALLBACK
             || n == SSL_R_INAPPROPRIATE_FALLBACK                     /*  373 */
 #endif
+#ifdef SSL_R_VERSION_TOO_LOW
+            || n == SSL_R_VERSION_TOO_LOW                            /*  396 */
+#endif
             || n == 1000 /* SSL_R_SSLV3_ALERT_CLOSE_NOTIFY */
 #ifdef SSL_R_SSLV3_ALERT_UNEXPECTED_MESSAGE
             || n == SSL_R_SSLV3_ALERT_UNEXPECTED_MESSAGE             /* 1010 */