[PATCH 0/2] Small cleanups to splice forwarding logic

[PATCH 0/2] Small cleanups to splice forwarding logic

[David Gibson]

While working on more flexible forwarding stuff, noticed a couple of
warts here.

David Gibson (2):
  fwd: Remove now-unnecessary handling of unspecified oaddr from splice
  fwd: Minor cleanup to fwd_nat_from_splice()

 fwd.c | 25 ++++++++-----------------
 1 file changed, 8 insertions(+), 17 deletions(-)

-- 
2.52.0

[PATCH 1/2] fwd: Remove now-unnecessary handling of unspecified oaddr from splice

[David Gibson]

fwd_nat_from_splice() has several cases that deal with the possibility of
ini->oaddr being unspecified.  That used to be a possible case, but since
e3c4c4175ce6 ("tcp: Always populate oaddr field for socket initiated
flows") and 59cc89f4cc01 ("udp, udp_flow: Track our specific address on
socket interfaces") we now always populate ini->oaddr with a specified
address for all flows.

Remove the now-unnecessary fallback logic.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 fwd.c | 9 ++-------
 1 file changed, 2 insertions(+), 7 deletions(-)

diff --git a/fwd.c b/fwd.c
index 44a0e109..9b701ad0 100644
--- a/fwd.c
+++ b/fwd.c
@@ -650,7 +650,7 @@ uint8_t fwd_nat_from_splice(const struct ctx *c, uint8_t proto,
 			    const struct flowside *ini, struct flowside *tgt)
 {
 	if (!inany_is_loopback(&ini->eaddr) ||
-	    (!inany_is_loopback(&ini->oaddr) && !inany_is_unspecified(&ini->oaddr))) {
+	    !inany_is_loopback(&ini->oaddr)) {
 		char estr[INANY_ADDRSTRLEN], fstr[INANY_ADDRSTRLEN];
 
 		debug("Non loopback address on %s: [%s]:%hu -> [%s]:%hu",
@@ -660,12 +660,7 @@ uint8_t fwd_nat_from_splice(const struct ctx *c, uint8_t proto,
 		return PIF_NONE;
 	}
 
-	if (!inany_is_unspecified(&ini->oaddr))
-		tgt->eaddr = ini->oaddr;
-	else if (inany_v4(&ini->oaddr))
-		tgt->eaddr = inany_loopback4;
-	else
-		tgt->eaddr = inany_loopback6;
+	tgt->eaddr = ini->oaddr;
 
 	/* Preserve the specific loopback address used, but let the kernel pick
 	 * a source port on the target side
-- 
2.52.0

[PATCH 2/2] fwd: Minor cleanup to fwd_nat_from_splice()

[David Gibson]

The order we do things in this function is slightly odd, and we have
a redundant assignment to tgt->oport.  Remove that, and re-order for
clarity.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 fwd.c | 16 ++++++----------
 1 file changed, 6 insertions(+), 10 deletions(-)

diff --git a/fwd.c b/fwd.c
index 9b701ad0..961c533f 100644
--- a/fwd.c
+++ b/fwd.c
@@ -660,13 +660,15 @@ uint8_t fwd_nat_from_splice(const struct ctx *c, uint8_t proto,
 		return PIF_NONE;
 	}
 
+	/* Preserve the src & dest (loopback) addresses */
+	tgt->oaddr = ini->eaddr;
 	tgt->eaddr = ini->oaddr;
 
-	/* Preserve the specific loopback address used, but let the kernel pick
-	 * a source port on the target side
-	 */
-	tgt->oaddr = ini->eaddr;
+	/* Let the kernel pick a host side source port */
 	tgt->oport = 0;
+	if (proto == IPPROTO_UDP)
+		/* But for UDP preserve the source port */
+		tgt->oport = ini->eport;
 
 	tgt->eport = ini->oport;
 	if (proto == IPPROTO_TCP)
@@ -674,12 +676,6 @@ uint8_t fwd_nat_from_splice(const struct ctx *c, uint8_t proto,
 	else if (proto == IPPROTO_UDP)
 		tgt->eport += c->udp.fwd_out.delta[tgt->eport];
 
-	/* Let the kernel pick a host side source port */
-	tgt->oport = 0;
-	if (proto == IPPROTO_UDP)
-		/* But for UDP preserve the source port */
-		tgt->oport = ini->eport;
-
 	return PIF_HOST;
 }
 
-- 
2.52.0