fwd, pif: Replace with pif_sock_l4() with pif_listen()

It turns out all users of pif_sock_l4() use it for "listening" sockets,
which now all have a common epoll reference format.  We can take advantage
of that to pass the necessary epoll information into pif_sock_l4() in a
more natural way, rather than as an opaque u32.

That in turn allows union fwd_listen_ref can become a struct, since the
union only exist to allow the meaningful fields to be coerced into a u32
for pif_sock_l4().

Rename pif_sock_l4() to pif_listen() to reflect the new semantics.  While
we're there, remove the static_assert() on the fwd_listen_ref's size.  We
do still need it to fit into 32 bits, but that constraint is imposed only
by the fact that it needs to fit into the whole, epoll_ref structure,
which we already check with a static_assert() in epoll_ctl.h.

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

6 files changed, 19 insertions, 33 deletions

diff --git a/epoll_ctl.h b/epoll_ctl.h
index 2c103cd..879763c 100644
--- a/epoll_ctl.h
+++ b/epoll_ctl.h
@@ -35,7 +35,7 @@ union epoll_ref {
 		union {
 			uint32_t flow;
 			flow_sidx_t flowside;
-			union fwd_listen_ref listen;
+			struct fwd_listen_ref listen;
 			uint32_t data;
 			int nsdir_fd;
 			int queue;
diff --git a/fwd.h b/fwd.h
index c0b30f3..7f52f76 100644
--- a/fwd.h
+++ b/fwd.h
@@ -57,20 +57,16 @@ struct fwd_rule {
 #define FWD_NO_HINT	(-1)
 
 /**
- * union fwd_listen_ref - information about a single listening socket
+ * struct fwd_listen_ref - information about a single listening socket
  * @port:	Bound port number of the socket
  * @pif:	pif in which the socket is listening
  * @rule:	Index of forwarding rule
  */
-union fwd_listen_ref {
-	struct {
-		in_port_t	port;
-		uint8_t		pif;
-		unsigned	rule :FWD_RULE_BITS;
-	};
-	uint32_t u32;
+struct fwd_listen_ref {
+	in_port_t	port;
+	uint8_t		pif;
+	unsigned	rule :FWD_RULE_BITS;
 };
-static_assert(sizeof(union fwd_listen_ref) == sizeof(uint32_t));
 
 enum fwd_ports_mode {
 	FWD_UNSET = 0,
diff --git a/pif.c b/pif.c
index 6ae970a..82a3b5e 100644
--- a/pif.c
+++ b/pif.c
@@ -62,23 +62,23 @@ void pif_sockaddr(const struct ctx *c, union sockaddr_inany *sa,
 	}
 }
 
-/** pif_sock_l4() - Open a socket bound to an address on a specified interface
+/** pif_listen() - Open a listening socket on a specified pif
  * @c:		Execution context
  * @type:	Socket epoll type
  * @pif:	Interface for this socket
  * @addr:	Address to bind to, or NULL for dual-stack any
  * @ifname:	Interface for binding, NULL for any
  * @port:	Port number to bind to (host byte order)
- * @data:	epoll reference portion for protocol handlers
+ * @rule:	Forwarding rule index this socket belongs to
  *
  * NOTE: For namespace pifs, this must be called having already entered the
  * relevant namespace.
  *
  * Return: newly created socket, negative error code on failure
  */
-int pif_sock_l4(const struct ctx *c, enum epoll_type type, uint8_t pif,
-		const union inany_addr *addr, const char *ifname,
-		in_port_t port, uint32_t data)
+int pif_listen(const struct ctx *c, enum epoll_type type, uint8_t pif,
+	       const union inany_addr *addr, const char *ifname,
+	       in_port_t port, unsigned rule)
 {
 	union epoll_ref ref;
 	int ret;
@@ -98,7 +98,9 @@ int pif_sock_l4(const struct ctx *c, enum epoll_type type, uint8_t pif,
 		return ref.fd;
 
 	ref.type = type;
-	ref.data = data;
+	ref.listen.port = port;
+	ref.listen.pif = pif;
+	ref.listen.rule = rule;
 
 	ret = epoll_add(c->epollfd, EPOLLIN, ref);
 	if (ret < 0) {
diff --git a/pif.h b/pif.h
index f4bec1e..e471fca 100644
--- a/pif.h
+++ b/pif.h
@@ -65,8 +65,8 @@ static inline bool pif_is_socket(uint8_t pif)
 
 void pif_sockaddr(const struct ctx *c, union sockaddr_inany *sa,
 		  uint8_t pif, const union inany_addr *addr, in_port_t port);
-int pif_sock_l4(const struct ctx *c, enum epoll_type type, uint8_t pif,
-		const union inany_addr *addr, const char *ifname,
-		in_port_t port, uint32_t data);
+int pif_listen(const struct ctx *c, enum epoll_type type, uint8_t pif,
+	       const union inany_addr *addr, const char *ifname,
+	       in_port_t port, unsigned rule);
 
 #endif /* PIF_H */
diff --git a/tcp.c b/tcp.c
index 1647070..a0d7cd8 100644
--- a/tcp.c
+++ b/tcp.c
@@ -2698,11 +2698,6 @@ void tcp_sock_handler(const struct ctx *c, union epoll_ref ref,
 int tcp_listen(const struct ctx *c, uint8_t pif, unsigned rule,
 	       const union inany_addr *addr, const char *ifname, in_port_t port)
 {
-	union fwd_listen_ref ref = {
-		.port = port,
-		.pif = pif,
-		.rule = rule,
-	};
 	int s;
 
 	ASSERT(!c->no_tcp);
@@ -2722,8 +2717,7 @@ int tcp_listen(const struct ctx *c, uint8_t pif, unsigned rule,
 			return -EAFNOSUPPORT;
 	}
 
-	s = pif_sock_l4(c, EPOLL_TYPE_TCP_LISTEN, pif, addr, ifname,
-			port, ref.u32);
+	s = pif_listen(c, EPOLL_TYPE_TCP_LISTEN, pif, addr, ifname, port, rule);
 
 	return s;
 }
diff --git a/udp.c b/udp.c
index 19adda0..464aa09 100644
--- a/udp.c
+++ b/udp.c
@@ -1139,11 +1139,6 @@ int udp_tap_handler(const struct ctx *c, uint8_t pif,
 int udp_listen(const struct ctx *c, uint8_t pif, unsigned rule,
 	       const union inany_addr *addr, const char *ifname, in_port_t port)
 {
-	union fwd_listen_ref ref = {
-		.pif = pif,
-		.port = port,
-		.rule = rule,
-	};
 	int s;
 
 	ASSERT(!c->no_udp);
@@ -1163,8 +1158,7 @@ int udp_listen(const struct ctx *c, uint8_t pif, unsigned rule,
 			return -EAFNOSUPPORT;
 	}
 
-	s = pif_sock_l4(c, EPOLL_TYPE_UDP_LISTEN, pif,
-			addr, ifname, port, ref.u32);
+	s = pif_listen(c, EPOLL_TYPE_UDP_LISTEN, pif, addr, ifname, port, rule);
 
 	return s;
 }