epoll: Split handling of listening TCP sockets into their own handler

tcp_sock_handler() handles both listening TCP sockets, and connected TCP
sockets, but what it needs to do in those cases has essentially nothing in
common.  Therefore, give listening sockets their own epoll_type value and
dispatch directly to their own handler from the top level.  Furthermore,
the two handlers need essentially entirely different information from the
reference: we re-(ab)used the index field in the tcp_epoll_ref to indicate
the port for the listening socket, but that's not the same meaning.  So,
switch listening sockets to their own reference type which we can lay out
as we please.  That lets us remove the listen and outbound fields from the
normal (connected) tcp_epoll_ref, reducing it to just the connection table
index.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

1 files changed, 22 insertions, 29 deletions

diff --git a/tcp.c b/tcp.c
index 98761a2..0322842 100644
--- a/tcp.c
+++ b/tcp.c
@@ -2735,7 +2735,8 @@ static void tcp_snat_inbound(const struct ctx *c, union inany_addr *addr)
  * @sa:		Peer socket address (from accept())
  * @now:	Current timestamp
  */
-static void tcp_tap_conn_from_sock(struct ctx *c, union epoll_ref ref,
+static void tcp_tap_conn_from_sock(struct ctx *c,
+				   union tcp_listen_epoll_ref ref,
 				   struct tcp_tap_conn *conn, int s,
 				   struct sockaddr *sa,
 				   const struct timespec *now)
@@ -2747,7 +2748,7 @@ static void tcp_tap_conn_from_sock(struct ctx *c, union epoll_ref ref,
 	conn_event(c, conn, SOCK_ACCEPTED);
 
 	inany_from_sockaddr(&conn->addr, &conn->sock_port, sa);
-	conn->tap_port = ref.tcp.index;
+	conn->tap_port = ref.port;
 
 	tcp_snat_inbound(c, &conn->addr);
 
@@ -2765,22 +2766,20 @@ static void tcp_tap_conn_from_sock(struct ctx *c, union epoll_ref ref,
 }
 
 /**
- * tcp_conn_from_sock() - Handle new connection request from listening socket
+ * tcp_listen_handler() - Handle new connection request from listening socket
  * @c:		Execution context
  * @ref:	epoll reference of listening socket
  * @now:	Current timestamp
  */
-static void tcp_conn_from_sock(struct ctx *c, union epoll_ref ref,
-			       const struct timespec *now)
+void tcp_listen_handler(struct ctx *c, union epoll_ref ref,
+			const struct timespec *now)
 {
 	struct sockaddr_storage sa;
 	union tcp_conn *conn;
 	socklen_t sl;
 	int s;
 
-	ASSERT(ref.tcp.listen);
-
-	if (c->tcp.conn_count >= TCP_MAX_CONNS)
+	if (c->no_tcp || c->tcp.conn_count >= TCP_MAX_CONNS)
 		return;
 
 	sl = sizeof(sa);
@@ -2796,11 +2795,11 @@ static void tcp_conn_from_sock(struct ctx *c, union epoll_ref ref,
 	conn = tc + c->tcp.conn_count++;
 
 	if (c->mode == MODE_PASTA &&
-	    tcp_splice_conn_from_sock(c, ref, &conn->splice,
+	    tcp_splice_conn_from_sock(c, ref.tcp_listen, &conn->splice,
 				      s, (struct sockaddr *)&sa))
 		return;
 
-	tcp_tap_conn_from_sock(c, ref, &conn->tap, s,
+	tcp_tap_conn_from_sock(c, ref.tcp_listen, &conn->tap, s,
 			       (struct sockaddr *)&sa, now);
 }
 
@@ -2926,19 +2925,10 @@ static void tcp_tap_sock_handler(struct ctx *c, struct tcp_tap_conn *conn,
  * @c:		Execution context
  * @ref:	epoll reference
  * @events:	epoll events bitmap
- * @now:	Current timestamp
  */
-void tcp_sock_handler(struct ctx *c, union epoll_ref ref, uint32_t events,
-		      const struct timespec *now)
+void tcp_sock_handler(struct ctx *c, union epoll_ref ref, uint32_t events)
 {
-	union tcp_conn *conn;
-
-	if (ref.tcp.listen) {
-		tcp_conn_from_sock(c, ref, now);
-		return;
-	}
-
-	conn = tc + ref.tcp.index;
+	union tcp_conn *conn = tc + ref.tcp.index;
 
 	if (conn->c.spliced)
 		tcp_splice_sock_handler(c, &conn->splice, ref.fd, events);
@@ -2959,8 +2949,9 @@ void tcp_sock_handler(struct ctx *c, union epoll_ref ref, uint32_t events,
 static int tcp_sock_init_af(const struct ctx *c, int af, in_port_t port,
 			    const struct in_addr *addr, const char *ifname)
 {
-	in_port_t idx = port + c->tcp.fwd_in.delta[port];
-	union tcp_epoll_ref tref = { .listen = 1, .index = idx };
+	union tcp_listen_epoll_ref tref = {
+		.port = port + c->tcp.fwd_in.delta[port],
+	};
 	int s;
 
 	s = sock_l4(c, af, IPPROTO_TCP, addr, ifname, port, tref.u32);
@@ -3019,9 +3010,10 @@ int tcp_sock_init(const struct ctx *c, sa_family_t af, const void *addr,
  */
 static void tcp_ns_sock_init4(const struct ctx *c, in_port_t port)
 {
-	in_port_t idx = port + c->tcp.fwd_out.delta[port];
-	union tcp_epoll_ref tref = { .listen = 1, .outbound = 1,
-				     .index = idx };
+	union tcp_listen_epoll_ref tref = {
+		.port = port + c->tcp.fwd_out.delta[port],
+		.ns = true,
+	};
 	struct in_addr loopback = { htonl(INADDR_LOOPBACK) };
 	int s;
 
@@ -3044,9 +3036,10 @@ static void tcp_ns_sock_init4(const struct ctx *c, in_port_t port)
  */
 static void tcp_ns_sock_init6(const struct ctx *c, in_port_t port)
 {
-	in_port_t idx = port + c->tcp.fwd_out.delta[port];
-	union tcp_epoll_ref tref = { .listen = 1, .outbound = 1,
-				     .index = idx };
+	union tcp_listen_epoll_ref tref = {
+		.port = port + c->tcp.fwd_out.delta[port],
+		.ns = true,
+	};
 	int s;
 
 	ASSERT(c->mode == MODE_PASTA);