Use TCP_NODELAY on TLS sockets to speed up the TLS handshake.

services/listen_dnsport.c

@@ -703,7 +703,10 @@ create_tcp_accept_sock(struct addrinfo *addr, int v6only, int* noproto,
 {
 	int s = -1;
 	char* err;
-#if defined(SO_REUSEADDR) || defined(SO_REUSEPORT) || defined(IPV6_V6ONLY) || defined(IP_TRANSPARENT) || defined(IP_BINDANY) || defined(IP_FREEBIND) || defined(SO_BINDANY)
+#if defined(SO_REUSEADDR) || defined(SO_REUSEPORT)		\
+	|| defined(IPV6_V6ONLY) || defined(IP_TRANSPARENT)	\
+	|| defined(IP_BINDANY) || defined(IP_FREEBIND)		\
+	|| defined(SO_BINDANY) || defined(TCP_NODELAY)
 	int on = 1;
 #endif
 #ifdef HAVE_SYSTEMD
@@ -1237,26 +1240,6 @@ set_recvpktinfo(int s, int family)
 	return 1;
 }
 
-/** see if interface is ssl, its port number == the ssl port number */
-static int
-if_is_ssl(const char* ifname, const char* port, int ssl_port,
-	struct config_strlist* tls_additional_port)
-{
-	struct config_strlist* s;
-	char* p = strchr(ifname, '@');
-	if(!p && atoi(port) == ssl_port)
-		return 1;
-	if(p && atoi(p+1) == ssl_port)
-		return 1;
-	for(s = tls_additional_port; s; s = s->next) {
-		if(p && atoi(p+1) == atoi(s->str))
-			return 1;
-		if(!p && atoi(port) == atoi(s->str))
-			return 1;
-	}
-	return 0;
-}
-
 /**
  * Helper for ports_open. Creates one interface (or NULL for default).
  * @param ifname: The interface ip address.
@@ -1300,10 +1283,16 @@ ports_create_if(const char* ifname, int do_auto, int do_udp, int do_tcp,
 	int quic_port, int http_notls_downstream, int sock_queue_timeout)
 {
 	int s, noip6=0;
+	int is_ssl = if_is_ssl(ifname, port, ssl_port, tls_additional_port);
 	int is_https = if_is_https(ifname, port, https_port);
 	int is_dnscrypt = if_is_dnscrypt(ifname, port, dnscrypt_port);
 	int is_pp2 = if_is_pp2(ifname, port, proxy_protocol_port);
-	int nodelay = is_https && http2_nodelay;
+	/* Always set TCP_NODELAY on TLS connection as it speeds up the TLS
+	 * handshake. DoH had already such option so we respect it.
+	 * Otherwise the server waits before sending more handshake data for
+	 * the client ACK (Nagle's algorithm), which is delayed because the
+	 * client waits for more data before ACKing (delayed ACK). */
+	int nodelay = is_https?http2_nodelay:is_ssl; 
 	struct unbound_socket* ub_sock;
 	int is_doq = if_is_quic(ifname, port, quic_port);
 	const char* add = NULL;

services/outside_network.c

@@ -262,12 +262,14 @@ pick_outgoing_tcp(struct pending_tcp* pend, struct waiting_tcp* w, int s)
 /** get TCP file descriptor for address, returns -1 on failure,
  * tcp_mss is 0 or maxseg size to set for TCP packets. */
 int
-outnet_get_tcp_fd(struct sockaddr_storage* addr, socklen_t addrlen, int tcp_mss, int dscp)
+outnet_get_tcp_fd(struct sockaddr_storage* addr, socklen_t addrlen,
+	int tcp_mss, int dscp, int nodelay)
 {
 	int s;
 	int af;
 	char* err;
-#if defined(SO_REUSEADDR) || defined(IP_BIND_ADDRESS_NO_PORT)
+#if defined(SO_REUSEADDR) || defined(IP_BIND_ADDRESS_NO_PORT)	\
+	|| defined(TCP_NODELAY)
 	int on = 1;
 #endif
 #ifdef INET6
@@ -320,6 +322,18 @@ outnet_get_tcp_fd(struct sockaddr_storage* addr, socklen_t addrlen, int tcp_mss,
 			" setsockopt(.. IP_BIND_ADDRESS_NO_PORT ..) failed");
 	}
 #endif /* IP_BIND_ADDRESS_NO_PORT */
+	if(nodelay) {
+#if defined(IPPROTO_TCP) && defined(TCP_NODELAY)
+		if(setsockopt(s, IPPROTO_TCP, TCP_NODELAY, (void*)&on,
+			(socklen_t)sizeof(on)) < 0) {
+			verbose(VERB_ALGO, "outgoing tcp:"
+				" setsockopt(.. TCP_NODELAY ..) failed");
+		}
+#else
+		verbose(VERB_ALGO, "outgoing tcp:"
+			" setsockopt(.. TCP_NODELAY ..) unsupported");
+#endif /* defined(IPPROTO_TCP) && defined(TCP_NODELAY) */
+	}
 	return s;
 }
 
@@ -649,7 +663,8 @@ outnet_tcp_take_into_use(struct waiting_tcp* w)
 	}
 
 	/* open socket */
-	s = outnet_get_tcp_fd(&w->addr, w->addrlen, w->outnet->tcp_mss, w->outnet->ip_dscp);
+	s = outnet_get_tcp_fd(&w->addr, w->addrlen, w->outnet->tcp_mss,
+		w->outnet->ip_dscp, w->ssl_upstream);
 
 	if(s == -1)
 		return 0;
@@ -3718,7 +3733,8 @@ outnet_comm_point_for_tcp(struct outside_network* outnet,
 	sldns_buffer* query, int timeout, int ssl, char* host)
 {
 	struct comm_point* cp;
-	int fd = outnet_get_tcp_fd(to_addr, to_addrlen, outnet->tcp_mss, outnet->ip_dscp);
+	int fd = outnet_get_tcp_fd(to_addr, to_addrlen, outnet->tcp_mss,
+		outnet->ip_dscp, ssl);
 	if(fd == -1) {
 		return 0;
 	}
@@ -3793,7 +3809,8 @@ outnet_comm_point_for_http(struct outside_network* outnet,
 {
 	/* cp calls cb with err=NETEVENT_DONE when transfer is done */
 	struct comm_point* cp;
-	int fd = outnet_get_tcp_fd(to_addr, to_addrlen, outnet->tcp_mss, outnet->ip_dscp);
+	int fd = outnet_get_tcp_fd(to_addr, to_addrlen, outnet->tcp_mss,
+		outnet->ip_dscp, ssl);
 	if(fd == -1) {
 		return 0;
 	}

services/outside_network.h

@@ -743,9 +743,11 @@ void reuse_write_wait_remove(struct reuse_tcp* reuse, struct waiting_tcp* w);
 void reuse_write_wait_push_back(struct reuse_tcp* reuse, struct waiting_tcp* w);
 
 /** get TCP file descriptor for address, returns -1 on failure,
- * tcp_mss is 0 or maxseg size to set for TCP packets. */
+ * tcp_mss is 0 or maxseg size to set for TCP packets,
+ * nodelay (TCP_NODELAY) should be set for TLS connections to speed up the TLS
+ * handshake.*/
 int outnet_get_tcp_fd(struct sockaddr_storage* addr, socklen_t addrlen,
-	int tcp_mss, int dscp);
+	int tcp_mss, int dscp, int nodelay);
 
 /**
  * Create udp commpoint suitable for sending packets to the destination.

testcode/fake_event.c

@@ -1938,7 +1938,8 @@ int comm_point_send_udp_msg(struct comm_point *c, sldns_buffer* packet,
 }
 
 int outnet_get_tcp_fd(struct sockaddr_storage* ATTR_UNUSED(addr),
-	socklen_t ATTR_UNUSED(addrlen), int ATTR_UNUSED(tcp_mss), int ATTR_UNUSED(dscp))
+	socklen_t ATTR_UNUSED(addrlen), int ATTR_UNUSED(tcp_mss),
+	int ATTR_UNUSED(dscp), int ATTR_UNUSED(nodelay))
 {
 	log_assert(0);
 	return -1;

util/config_file.c

@@ -2796,6 +2796,26 @@ int cfg_has_https(struct config_file* cfg)
 	return 0;
 }
 
+/** see if interface is ssl, its port number == the ssl port number */
+int
+if_is_ssl(const char* ifname, const char* port, int ssl_port,
+	struct config_strlist* tls_additional_port)
+{
+	struct config_strlist* s;
+	char* p = strchr(ifname, '@');
+	if(!p && atoi(port) == ssl_port)
+		return 1;
+	if(p && atoi(p+1) == ssl_port)
+		return 1;
+	for(s = tls_additional_port; s; s = s->next) {
+		if(p && atoi(p+1) == atoi(s->str))
+			return 1;
+		if(!p && atoi(port) == atoi(s->str))
+			return 1;
+	}
+	return 0;
+}
+
 /** see if interface is PROXYv2, its port number == the proxy port number */
 int
 if_is_pp2(const char* ifname, const char* port,

util/config_file.h

@@ -1405,6 +1405,10 @@ int if_is_https(const char* ifname, const char* port, int https_port);
  */
 int cfg_has_https(struct config_file* cfg);
 
+/** see if interface is ssl, its port number == the ssl port number */
+int if_is_ssl(const char* ifname, const char* port, int ssl_port,
+	struct config_strlist* tls_additional_port);
+
 /** see if interface is PROXYv2, its port number == the proxy port number */
 int if_is_pp2(const char* ifname, const char* port,
 	struct config_strlist* proxy_protocol_port);