[nginx] SSL: moved c->ssl->handshaked check in server name callback.

[Maxim Dounin]

details:   https://hg.nginx.org/nginx/rev/49f9d2f7d887
branches:  
changeset: 7475:49f9d2f7d887
user:      Maxim Dounin <mdounin at mdounin.ru>
date:      Tue Mar 05 16:34:19 2019 +0300
description:
SSL: moved c->ssl->handshaked check in server name callback.

Server name callback is always called by OpenSSL, even
if server_name extension is not present in ClientHello.  As such,
checking c->ssl->handshaked before the SSL_get_servername() result
should help to more effectively prevent renegotiation in
OpenSSL 1.1.0 - 1.1.0g, where neither SSL3_FLAGS_NO_RENEGOTIATE_CIPHERS
nor SSL_OP_NO_RENEGOTIATION is available.

diffstat:

 src/http/ngx_http_request.c |  12 ++++++------
 1 files changed, 6 insertions(+), 6 deletions(-)

diffs (29 lines):

diff --git a/src/http/ngx_http_request.c b/src/http/ngx_http_request.c
--- a/src/http/ngx_http_request.c
+++ b/src/http/ngx_http_request.c
@@ -864,12 +864,6 @@ ngx_http_ssl_servername(ngx_ssl_conn_t *
     ngx_http_core_loc_conf_t  *clcf;
     ngx_http_core_srv_conf_t  *cscf;
 
-    servername = SSL_get_servername(ssl_conn, TLSEXT_NAMETYPE_host_name);
-
-    if (servername == NULL) {
-        return SSL_TLSEXT_ERR_OK;
-    }
-
     c = ngx_ssl_get_connection(ssl_conn);
 
     if (c->ssl->handshaked) {
@@ -877,6 +871,12 @@ ngx_http_ssl_servername(ngx_ssl_conn_t *
         return SSL_TLSEXT_ERR_ALERT_FATAL;
     }
 
+    servername = SSL_get_servername(ssl_conn, TLSEXT_NAMETYPE_host_name);
+
+    if (servername == NULL) {
+        return SSL_TLSEXT_ERR_OK;
+    }
+
     ngx_log_debug1(NGX_LOG_DEBUG_HTTP, c->log, 0,
                    "SSL server name: \"%s\"", servername);