SSL: save sessions for upstream peers using a callback function.

In TLSv1.3, NewSessionTicket messages arrive after the handshake and
can come at any time.  Therefore we use a callback to save the session
when we know about it.  This approach works for < TLSv1.3 as well.
The callback function is set once per location on merge phase.

Since SSL_get_session() in BoringSSL returns an unresumable session for
TLSv1.3, peer save_session() methods have been updated as well to use a
session supplied within the callback.  To preserve API, the session is
cached in c->ssl->session.  It is preferably accessed in save_session()
methods by ngx_ssl_get_session() and ngx_ssl_get0_session() wrappers.

1 files changed, 24 insertions, 4 deletions

diff --git a/src/http/ngx_http_upstream.c b/src/http/ngx_http_upstream.c
index aba1fbb07..63fa5d998 100644
--- a/src/http/ngx_http_upstream.c
+++ b/src/http/ngx_http_upstream.c
@@ -187,6 +187,7 @@ static void ngx_http_upstream_ssl_init_connection(ngx_http_request_t *,
 static void ngx_http_upstream_ssl_handshake_handler(ngx_connection_t *c);
 static void ngx_http_upstream_ssl_handshake(ngx_http_request_t *,
     ngx_http_upstream_t *u, ngx_connection_t *c);
+static void ngx_http_upstream_ssl_save_session(ngx_connection_t *c);
 static ngx_int_t ngx_http_upstream_ssl_name(ngx_http_request_t *r,
     ngx_http_upstream_t *u, ngx_connection_t *c);
 #endif
@@ -1675,6 +1676,8 @@ ngx_http_upstream_ssl_init_connection(ngx_http_request_t *r,
     }
 
     if (u->conf->ssl_session_reuse) {
+        c->ssl->save_session = ngx_http_upstream_ssl_save_session;
+
         if (u->peer.set_session(&u->peer, u->peer.data) != NGX_OK) {
             ngx_http_upstream_finalize_request(r, u,
                                                NGX_HTTP_INTERNAL_SERVER_ERROR);
@@ -1759,10 +1762,6 @@ ngx_http_upstream_ssl_handshake(ngx_http_request_t *r, ngx_http_upstream_t *u,
             }
         }
 
-        if (u->conf->ssl_session_reuse) {
-            u->peer.save_session(&u->peer, u->peer.data);
-        }
-
         c->write->handler = ngx_http_upstream_handler;
         c->read->handler = ngx_http_upstream_handler;
 
@@ -1782,6 +1781,27 @@ failed:
 }
 
 
+static void
+ngx_http_upstream_ssl_save_session(ngx_connection_t *c)
+{
+    ngx_http_request_t   *r;
+    ngx_http_upstream_t  *u;
+
+    if (c->idle) {
+        return;
+    }
+
+    r = c->data;
+
+    u = r->upstream;
+    c = r->connection;
+
+    ngx_http_set_log_request(c->log, r);
+
+    u->peer.save_session(&u->peer, u->peer.data);
+}
+
+
 static ngx_int_t
 ngx_http_upstream_ssl_name(ngx_http_request_t *r, ngx_http_upstream_t *u,
     ngx_connection_t *c)