[PATCH v2 8/8] tcp, udp: Don't exclude ports in {tcp,udp}_port_rebind()

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

To avoid circular forwarding, {tcp,udp}_port_rebind() refuse to listen on
ports that we're already listening on in the reverse direction.  This is
redundant, because we already remove such ports from the forward map when
we scan.  This was needed previously, because our reverse maps might have
been one cycle out of date, so could be missing a newly appeared port.

We've now rearranged the port scanning code to avoid that, so we don't need
the check in tcp_port_rebind() any more.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 tcp.c | 5 -----
 udp.c | 6 ------
 2 files changed, 11 deletions(-)

diff --git a/tcp.c b/tcp.c
index c35c1c3f..e91c0cf5 100644
--- a/tcp.c
+++ b/tcp.c
@@ -2832,7 +2832,6 @@ int tcp_init(struct ctx *c)
 static void tcp_port_rebind(struct ctx *c, bool outbound)
 {
 	const uint8_t *fmap = outbound ? c->tcp.fwd_out.map : c->tcp.fwd_in.map;
-	const uint8_t *rmap = outbound ? c->tcp.fwd_in.map : c->tcp.fwd_out.map;
 	int (*socks)[IP_VERSIONS] = outbound ? tcp_sock_ns : tcp_sock_init_ext;
 	unsigned port;
 
@@ -2851,10 +2850,6 @@ static void tcp_port_rebind(struct ctx *c, bool outbound)
 			continue;
 		}
 
-		/* Don't loop back our own ports */
-		if (bitmap_isset(rmap, port))
-			continue;
-
 		if ((c->ifi4 && socks[port][V4] == -1) ||
 		    (c->ifi6 && socks[port][V6] == -1)) {
 			if (outbound)
diff --git a/udp.c b/udp.c
index 8cff8809..9c009502 100644
--- a/udp.c
+++ b/udp.c
@@ -1204,8 +1204,6 @@ static void udp_port_rebind(struct ctx *c, bool outbound)
 	int (*socks)[NUM_PORTS] = outbound ? udp_splice_ns : udp_splice_init;
 	const uint8_t *fmap
 		= outbound ? c->udp.fwd_out.map : c->udp.fwd_in.map;
-	const uint8_t *rmap
-		= outbound ? c->udp.fwd_in.map : c->udp.fwd_out.map;
 	unsigned port;
 
 	for (port = 0; port < NUM_PORTS; port++) {
@@ -1223,10 +1221,6 @@ static void udp_port_rebind(struct ctx *c, bool outbound)
 			continue;
 		}
 
-		/* Don't loop back our own ports */
-		if (bitmap_isset(rmap, port))
-			continue;
-
 		if ((c->ifi4 && socks[V4][port] == -1) ||
 		    (c->ifi6 && socks[V6][port] == -1))
 			udp_sock_init(c, outbound, NULL, NULL, port);
-- 
2.51.0