[PATCH v3 13/14] fwd, tcp, udp: Add forwarding rule to listening socket epoll references

[David Gibson <david@gibson.dropbear.id.au>]

Now that we have a table of all our forwarding rules, every listening
socket can be associated with a specific rule.  Add an index allowing us to
locate that rule from the socket's epoll reference.  We don't use it yet,
but we'll use it to optimise rule lookup when forwarding new flows.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 fwd.c | 15 ++++++++++-----
 fwd.h |  5 +++++
 tcp.c |  4 +++-
 tcp.h |  5 ++---
 udp.c |  4 +++-
 udp.h |  5 ++---
 6 files changed, 25 insertions(+), 13 deletions(-)

diff --git a/fwd.c b/fwd.c
index 7c4575ff..6727d26f 100644
--- a/fwd.c
+++ b/fwd.c
@@ -474,6 +474,7 @@ void fwd_rules_print(const struct fwd_ports *fwd)
 
 /** fwd_sync_one() - Create or remove listening sockets for a forward entry
  * @c:		Execution context
+ * @fwd:	Forwarding table
  * @rule:	Forwarding rule
  * @pif:	Interface to create listening sockets for
  * @proto:	Protocol to listen for
@@ -481,19 +482,23 @@ void fwd_rules_print(const struct fwd_ports *fwd)
  *
  * Return: 0 on success, -1 on failure
  */
-static int fwd_sync_one(const struct ctx *c, const struct fwd_rule *rule,
+static int fwd_sync_one(const struct ctx *c,
+			const struct fwd_ports *fwd, const struct fwd_rule *rule,
 			uint8_t pif, uint8_t proto, const uint8_t *scanmap)
 {
 	const union inany_addr *addr = fwd_rule_addr(rule);
 	const char *ifname = rule->ifname;
 	bool bound_one = false;
-	unsigned port;
+	unsigned port, idx;
 
 	ASSERT(pif_is_socket(pif));
 
 	if (!*ifname)
 		ifname = NULL;
 
+	idx = rule - fwd->rules;
+	ASSERT(idx < MAX_FWD_RULES);
+	
 	for (port = rule->first; port <= rule->last; port++) {
 		int fd = rule->socks[port - rule->first];
 
@@ -514,9 +519,9 @@ static int fwd_sync_one(const struct ctx *c, const struct fwd_rule *rule,
 		}
 
 		if (proto == IPPROTO_TCP)
-			fd = tcp_listen(c, pif, addr, ifname, port);
+			fd = tcp_listen(c, pif, idx, addr, ifname, port);
 		else if (proto == IPPROTO_UDP)
-			fd = udp_listen(c, pif, addr, ifname, port);
+			fd = udp_listen(c, pif, idx, addr, ifname, port);
 		else
 			ASSERT(0);
 
@@ -588,7 +593,7 @@ static int fwd_listen_sync_(void *arg)
 		ns_enter(a->c);
 
 	for (i = 0; i < a->fwd->count; i++) {
-		a->ret = fwd_sync_one(a->c, &a->fwd->rules[i],
+		a->ret = fwd_sync_one(a->c, a->fwd, &a->fwd->rules[i],
 				      a->pif, a->proto, a->fwd->map);
 		if (a->ret < 0)
 			break;
diff --git a/fwd.h b/fwd.h
index cfe9ed46..435f422a 100644
--- a/fwd.h
+++ b/fwd.h
@@ -48,14 +48,19 @@ struct fwd_rule {
  * union 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;
+#define FWD_RULE_BITS	8
+		unsigned	rule :FWD_RULE_BITS;
 	};
 	uint32_t u32;
 };
+static_assert(sizeof(union fwd_listen_ref) == sizeof(uint32_t));
+static_assert(MAX_FWD_RULES <= (1U << FWD_RULE_BITS));
 
 enum fwd_ports_mode {
 	FWD_UNSET = 0,
diff --git a/tcp.c b/tcp.c
index e9b440da..fc03e38f 100644
--- a/tcp.c
+++ b/tcp.c
@@ -2672,18 +2672,20 @@ void tcp_sock_handler(const struct ctx *c, union epoll_ref ref,
  * tcp_listen() - Create listening socket
  * @c:		Execution context
  * @pif:	Interface to open the socket for (PIF_HOST or PIF_SPLICE)
+ * @rule:	Index of relevant forwarding rule
  * @addr:	Pointer to address for binding, NULL for any
  * @ifname:	Name of interface to bind to, NULL for any
  * @port:	Port, host order
  *
  * Return: Socket fd on success, negative error code on failure
  */
-int tcp_listen(const struct ctx *c, uint8_t pif,
+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;
 
diff --git a/tcp.h b/tcp.h
index 45f97d93..24b90870 100644
--- a/tcp.h
+++ b/tcp.h
@@ -18,9 +18,8 @@ void tcp_sock_handler(const struct ctx *c, union epoll_ref ref,
 int tcp_tap_handler(const struct ctx *c, uint8_t pif, sa_family_t af,
 		    const void *saddr, const void *daddr, uint32_t flow_lbl,
 		    const struct pool *p, int idx, const struct timespec *now);
-int tcp_listen(const struct ctx *c, uint8_t pif,
-	       const union inany_addr *addr, const char *ifname,
-	       in_port_t port);
+int tcp_listen(const struct ctx *c, uint8_t pif, unsigned rule,
+	       const union inany_addr *addr, const char *ifname, in_port_t port);
 int tcp_init(struct ctx *c);
 void tcp_timer(const struct ctx *c, const struct timespec *now);
 void tcp_defer_handler(struct ctx *c);
diff --git a/udp.c b/udp.c
index 92a87198..761221f6 100644
--- a/udp.c
+++ b/udp.c
@@ -1115,18 +1115,20 @@ int udp_tap_handler(const struct ctx *c, uint8_t pif,
  * udp_listen() - Initialise listening socket for a given port
  * @c:		Execution context
  * @pif:	Interface to open the socket for (PIF_HOST or PIF_SPLICE)
+ * @rule:	Index of relevant forwarding rule
  * @addr:	Pointer to address for binding, NULL if not configured
  * @ifname:	Name of interface to bind to, NULL if not configured
  * @port:	Port, host order
  *
  * Return: Socket fd on success, negative error code on failure
  */
-int udp_listen(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;
 
diff --git a/udp.h b/udp.h
index 3c6f90a9..2b91d728 100644
--- a/udp.h
+++ b/udp.h
@@ -14,9 +14,8 @@ int udp_tap_handler(const struct ctx *c, uint8_t pif,
 		    sa_family_t af, const void *saddr, const void *daddr,
 		    uint8_t ttl, const struct pool *p, int idx,
 		    const struct timespec *now);
-int udp_listen(const struct ctx *c, uint8_t pif,
-	       const union inany_addr *addr, const char *ifname,
-	       in_port_t port);
+int udp_listen(const struct ctx *c, uint8_t pif, unsigned rule,
+	       const union inany_addr *addr, const char *ifname, in_port_t port);
 int udp_init(struct ctx *c);
 void udp_update_l2_buf(const unsigned char *eth_d);
 
-- 
2.52.0