- if (want_cookie) {
- isn = cookie_v6_init_sequence(sk, skb, &req->mss);
- req->cookie_ts = tmp_opt.tstamp_ok;
- goto have_isn;
- }
-
- /* VJ's idea. We save last timestamp seen
- * from the destination in peer table, when entering
- * state TIME-WAIT, and check against it before
- * accepting new connection request.
- *
- * If "isn" is not zero, this request hit alive
- * timewait bucket, so that all the necessary checks
- * are made in the function processing timewait state.
- */
- if (tmp_opt.saw_tstamp &&
- tcp_death_row.sysctl_tw_recycle &&
- (dst = inet6_csk_route_req(sk, &fl6, req)) != NULL) {
- if (!tcp_peer_is_proven(req, dst, true)) {
- NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_PAWSPASSIVEREJECTED);
- goto drop_and_release;
- }
- }
- /* Kill the following clause, if you dislike this way. */
- else if (!sysctl_tcp_syncookies &&
- (sysctl_max_syn_backlog - inet_csk_reqsk_queue_len(sk) <
- (sysctl_max_syn_backlog >> 2)) &&
- !tcp_peer_is_proven(req, dst, false)) {
- /* Without syncookies last quarter of
- * backlog is filled with destinations,
- * proven to be alive.
- * It means that we continue to communicate
- * to destinations, already remembered
- * to the moment of synflood.
- */
- LIMIT_NETDEBUG(KERN_DEBUG "TCP: drop open request from %pI6/%u\n",
- &ireq->ir_v6_rmt_addr, ntohs(tcp_hdr(skb)->source));
- goto drop_and_release;
- }
-
- isn = tcp_v6_init_sequence(skb);
- }
-have_isn:
-
- if (security_inet_conn_request(sk, skb, req))
- goto drop_and_release;
-
- if (!dst && (dst = inet6_csk_route_req(sk, &fl6, req)) == NULL)
- goto drop_and_free;
-
- tcp_rsk(req)->snt_isn = isn;
- tcp_rsk(req)->snt_synack = tcp_time_stamp;
- tcp_openreq_init_rwin(req, sk, dst);
- fastopen = !want_cookie &&
- tcp_try_fastopen(sk, skb, req, &foc, dst);
- err = tcp_v6_send_synack(sk, dst, &fl6, req,
- skb_get_queue_mapping(skb), &foc);
- if (!fastopen) {
- if (err || want_cookie)
- goto drop_and_free;
-
- tcp_rsk(req)->listener = NULL;
- inet6_csk_reqsk_queue_hash_add(sk, req, TCP_TIMEOUT_INIT);
- }
- return 0;
-
-drop_and_release:
- dst_release(dst);
-drop_and_free:
- reqsk_free(req);