[PATCH 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.  I believe this was needed, because previously our reverse maps
might be one cycle out of date, so could be missing a newly appeared port.

We've now rearrange 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 a330538d..99a8a4c0 100644
--- a/tcp.c
+++ b/tcp.c
@@ -2817,7 +2817,6 @@ 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;
 
@@ -2836,10 +2835,6 @@ 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 e27b2219..4af98503 100644
--- a/udp.c
+++ b/udp.c
@@ -1191,8 +1191,6 @@ 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++) {
@@ -1210,10 +1208,6 @@ 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