tcp, udp, fwd: Run all port scanning from a single timer

With -t auto and similar options we need to periodically scan /proc for
listening ports.  Currently we do this separately for TCP and UDP, from
tcp_timer() and udp_timer().

For upcoming changes (leading eventually to a more general forwarding
table), it's awkward to have these separate.  Move them to a single common
timer.  For now this just calls new tcp_scan_ports() and udp_scan_ports()
functions, but we'll consolidate more thoroughly in later patches.

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

7 files changed, 65 insertions, 38 deletions

diff --git a/fwd.c b/fwd.c
index 539b290..6e248fe 100644
--- a/fwd.c
+++ b/fwd.c
@@ -442,6 +442,30 @@ void fwd_scan_ports_init(struct ctx *c)
 	}
 }
 
+/* Last time we scanned for open ports */
+static struct timespec scan_ports_run;
+
+/**
+ * fwd_scan_ports_timer() - Rescan open port information when necessary
+ * @c:		Execution context
+ * @now:	Current (monotonic) time
+ */
+void fwd_scan_ports_timer(struct ctx *c, const struct timespec *now)
+{
+	if (c->mode != MODE_PASTA)
+		return;
+
+	if (timespec_diff_ms(now, &scan_ports_run) < FWD_PORT_SCAN_INTERVAL)
+		return;
+
+	scan_ports_run = *now;
+
+	if (!c->no_tcp)
+		tcp_scan_ports(c);
+	if (!c->no_udp)
+		udp_scan_ports(c);
+}
+
 /**
  * is_dns_flow() - Determine if flow appears to be a DNS request
  * @proto:	Protocol (IP L4 protocol number)
diff --git a/fwd.h b/fwd.h
index 352f3b5..ec7bb3b 100644
--- a/fwd.h
+++ b/fwd.h
@@ -42,11 +42,14 @@ struct fwd_ports {
 	in_port_t delta[NUM_PORTS];
 };
 
+#define FWD_PORT_SCAN_INTERVAL		1000	/* ms */
+
 void fwd_scan_ports_tcp(struct fwd_ports *fwd, const struct fwd_ports *rev);
 void fwd_scan_ports_udp(struct fwd_ports *fwd, const struct fwd_ports *rev,
 			const struct fwd_ports *tcp_fwd,
 			const struct fwd_ports *tcp_rev);
 void fwd_scan_ports_init(struct ctx *c);
+void fwd_scan_ports_timer(struct ctx *c, const struct timespec *now);
 
 bool nat_inbound(const struct ctx *c, const union inany_addr *addr,
 		 union inany_addr *translated);
diff --git a/passt.c b/passt.c
index 5d3ad55..4964427 100644
--- a/passt.c
+++ b/passt.c
@@ -57,7 +57,7 @@
 
 #define NUM_EPOLL_EVENTS	8
 
-#define TIMER_INTERVAL_		MIN(TCP_TIMER_INTERVAL, UDP_TIMER_INTERVAL)
+#define TIMER_INTERVAL_		MIN(TCP_TIMER_INTERVAL, FWD_PORT_SCAN_INTERVAL)
 #define TIMER_INTERVAL		MIN(TIMER_INTERVAL_, FLOW_TIMER_INTERVAL)
 
 char pkt_buf[PKT_BUF_BYTES]	__attribute__ ((aligned(PAGE_SIZE)));
@@ -119,11 +119,10 @@ static void post_handler(struct ctx *c, const struct timespec *now)
 
 	/* NOLINTNEXTLINE(bugprone-branch-clone): intervals can be the same */
 	CALL_PROTO_HANDLER(tcp, TCP);
-	/* NOLINTNEXTLINE(bugprone-branch-clone): intervals can be the same */
-	CALL_PROTO_HANDLER(udp, UDP);
+#undef CALL_PROTO_HANDLER
 
 	flow_defer_handler(c, now);
-#undef CALL_PROTO_HANDLER
+	fwd_scan_ports_timer(c, now);
 
 	if (!c->no_ndp)
 		ndp_timer(c, now);
diff --git a/tcp.c b/tcp.c
index 8cf4459..fc1a261 100644
--- a/tcp.c
+++ b/tcp.c
@@ -2884,25 +2884,32 @@ static int tcp_port_rebind_outbound(void *arg)
 }
 
 /**
- * tcp_timer() - Periodic tasks: port detection, closed connections, pool refill
+ * tcp_scan_ports() - Update forwarding maps based on scan of listening ports
  * @c:		Execution context
- * @now:	Current timestamp
  */
-void tcp_timer(struct ctx *c, const struct timespec *now)
+void tcp_scan_ports(struct ctx *c)
 {
-	(void)now;
+	ASSERT(c->mode == MODE_PASTA && !c->no_tcp);
 
-	if (c->mode == MODE_PASTA) {
-		if (c->tcp.fwd_out.mode == FWD_AUTO) {
-			fwd_scan_ports_tcp(&c->tcp.fwd_out, &c->tcp.fwd_in);
-			NS_CALL(tcp_port_rebind_outbound, c);
-		}
+	if (c->tcp.fwd_out.mode == FWD_AUTO) {
+		fwd_scan_ports_tcp(&c->tcp.fwd_out, &c->tcp.fwd_in);
+		NS_CALL(tcp_port_rebind_outbound, c);
+	}
 
-		if (c->tcp.fwd_in.mode == FWD_AUTO) {
-			fwd_scan_ports_tcp(&c->tcp.fwd_in, &c->tcp.fwd_out);
-			tcp_port_rebind(c, false);
-		}
+	if (c->tcp.fwd_in.mode == FWD_AUTO) {
+		fwd_scan_ports_tcp(&c->tcp.fwd_in, &c->tcp.fwd_out);
+		tcp_port_rebind(c, false);
 	}
+}
+
+/**
+ * tcp_timer() - Periodic tasks: port detection, closed connections, pool refill
+ * @c:		Execution context
+ * @now:	Current timestamp
+ */
+void tcp_timer(const struct ctx *c, const struct timespec *now)
+{
+	(void)now;
 
 	tcp_sock_refill_init(c);
 	if (c->mode == MODE_PASTA)
diff --git a/tcp.h b/tcp.h
index c1b8385..9cd736d 100644
--- a/tcp.h
+++ b/tcp.h
@@ -21,7 +21,8 @@ int tcp_tap_handler(const struct ctx *c, uint8_t pif, sa_family_t af,
 int tcp_sock_init(const struct ctx *c, const union inany_addr *addr,
 		  const char *ifname, in_port_t port);
 int tcp_init(struct ctx *c);
-void tcp_timer(struct ctx *c, const struct timespec *now);
+void tcp_scan_ports(struct ctx *c);
+void tcp_timer(const struct ctx *c, const struct timespec *now);
 void tcp_defer_handler(struct ctx *c);
 
 void tcp_update_l2_buf(const unsigned char *eth_d);
diff --git a/udp.c b/udp.c
index f052a0c..d95ef2f 100644
--- a/udp.c
+++ b/udp.c
@@ -1252,28 +1252,23 @@ static int udp_port_rebind_outbound(void *arg)
 }
 
 /**
- * udp_timer() - Scan activity bitmaps for ports with associated timed events
+ * udp_scan_ports() - Update forwarding maps based on scan of listening ports
  * @c:		Execution context
- * @now:	Current timestamp
  */
-void udp_timer(struct ctx *c, const struct timespec *now)
+void udp_scan_ports(struct ctx *c)
 {
-	(void)now;
-
-	ASSERT(!c->no_udp);
+	ASSERT(c->mode == MODE_PASTA && !c->no_udp);
 
-	if (c->mode == MODE_PASTA) {
-		if (c->udp.fwd_out.mode == FWD_AUTO) {
-			fwd_scan_ports_udp(&c->udp.fwd_out, &c->udp.fwd_in,
-					   &c->tcp.fwd_out, &c->tcp.fwd_in);
-			NS_CALL(udp_port_rebind_outbound, c);
-		}
+	if (c->udp.fwd_out.mode == FWD_AUTO) {
+		fwd_scan_ports_udp(&c->udp.fwd_out, &c->udp.fwd_in,
+				   &c->tcp.fwd_out, &c->tcp.fwd_in);
+		NS_CALL(udp_port_rebind_outbound, c);
+	}
 
-		if (c->udp.fwd_in.mode == FWD_AUTO) {
-			fwd_scan_ports_udp(&c->udp.fwd_in, &c->udp.fwd_out,
-					   &c->tcp.fwd_in, &c->tcp.fwd_out);
-			udp_port_rebind(c, false);
-		}
+	if (c->udp.fwd_in.mode == FWD_AUTO) {
+		fwd_scan_ports_udp(&c->udp.fwd_in, &c->udp.fwd_out,
+				   &c->tcp.fwd_in, &c->tcp.fwd_out);
+		udp_port_rebind(c, false);
 	}
 }
 
diff --git a/udp.h b/udp.h
index dd6e5ad..e3fb78b 100644
--- a/udp.h
+++ b/udp.h
@@ -6,8 +6,6 @@
 #ifndef UDP_H
 #define UDP_H
 
-#define UDP_TIMER_INTERVAL		1000 /* ms */
-
 void udp_portmap_clear(void);
 void udp_listen_sock_handler(const struct ctx *c, union epoll_ref ref,
 			     uint32_t events, const struct timespec *now);
@@ -20,7 +18,7 @@ int udp_tap_handler(const struct ctx *c, uint8_t pif,
 int udp_sock_init(const struct ctx *c, int ns, const union inany_addr *addr,
 		  const char *ifname, in_port_t port);
 int udp_init(struct ctx *c);
-void udp_timer(struct ctx *c, const struct timespec *now);
+void udp_scan_ports(struct ctx *c);
 void udp_update_l2_buf(const unsigned char *eth_d);
 
 /**