[PATCH 05/16] inany: Helper to test for IPv4 or IPv6 loopback address

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

tcp_splice_conn_from_sock() needs to check if an inany is either the IPv6
loopback address (::) or an IPv4 loopback address (127.0.0.0/8).  We may
have other places that also want to check this in future, so simplify it
with an inany_is_loopback() helper.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 inany.h      | 13 +++++++++++++
 tcp_splice.c | 14 +++-----------
 2 files changed, 16 insertions(+), 11 deletions(-)

diff --git a/inany.h b/inany.h
index fe652ff7..d758f7ba 100644
--- a/inany.h
+++ b/inany.h
@@ -55,6 +55,19 @@ static inline bool inany_equals(const union inany_addr *a,
 	return IN6_ARE_ADDR_EQUAL(&a->a6, &b->a6);
 }
 
+/** inany_is_loopback - Check if address is loopback
+ * @a:		IPv[46] address
+ *
+ * Return: true if @a is either ::1 or in 127.0.0.1/8
+ */
+static inline bool inany_is_loopback(const union inany_addr *a)
+{
+	const struct in_addr *v4;
+
+	return IN6_IS_ADDR_LOOPBACK(&a->a6) ||
+		((v4 = inany_v4(a)) && IN4_IS_ADDR_LOOPBACK(v4));
+}
+
 /** inany_from_af - Set IPv[46] address from IPv4 or IPv6 address
  * @aa:		Pointer to store IPv[46] address
  * @af:		Address family of @addr
diff --git a/tcp_splice.c b/tcp_splice.c
index 76258e89..fbce4879 100644
--- a/tcp_splice.c
+++ b/tcp_splice.c
@@ -436,24 +436,16 @@ bool tcp_splice_conn_from_sock(const struct ctx *c,
 			       struct tcp_splice_conn *conn, int s,
 			       const struct sockaddr *sa)
 {
-	const struct in_addr *a4;
 	union inany_addr aany;
 	in_port_t port;
 
 	ASSERT(c->mode == MODE_PASTA);
 
 	inany_from_sockaddr(&aany, &port, sa);
-	a4 = inany_v4(&aany);
+	if (!inany_is_loopback(&aany))
+		return false;
 
-	if (a4) {
-		if (!IN4_IS_ADDR_LOOPBACK(a4))
-			return false;
-		conn->flags = 0;
-	} else {
-		if (!IN6_IS_ADDR_LOOPBACK(&aany.a6))
-			return false;
-		conn->flags = SPLICE_V6;
-	}
+	conn->flags = inany_v4(&aany) ? 0 : SPLICE_V6;
 
 	if (setsockopt(s, SOL_TCP, TCP_QUICKACK, &((int){ 1 }), sizeof(int)))
 		flow_trace(conn, "failed to set TCP_QUICKACK on %i", s);
-- 
@@ -436,24 +436,16 @@ bool tcp_splice_conn_from_sock(const struct ctx *c,
 			       struct tcp_splice_conn *conn, int s,
 			       const struct sockaddr *sa)
 {
-	const struct in_addr *a4;
 	union inany_addr aany;
 	in_port_t port;
 
 	ASSERT(c->mode == MODE_PASTA);
 
 	inany_from_sockaddr(&aany, &port, sa);
-	a4 = inany_v4(&aany);
+	if (!inany_is_loopback(&aany))
+		return false;
 
-	if (a4) {
-		if (!IN4_IS_ADDR_LOOPBACK(a4))
-			return false;
-		conn->flags = 0;
-	} else {
-		if (!IN6_IS_ADDR_LOOPBACK(&aany.a6))
-			return false;
-		conn->flags = SPLICE_V6;
-	}
+	conn->flags = inany_v4(&aany) ? 0 : SPLICE_V6;
 
 	if (setsockopt(s, SOL_TCP, TCP_QUICKACK, &((int){ 1 }), sizeof(int)))
 		flow_trace(conn, "failed to set TCP_QUICKACK on %i", s);
-- 
2.43.0