[PATCH 13/16] util: Provide global constants for IPv4 loopback and unspecified address

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

For various reasons, the standard library doesn't provide IPv4 loopback and
unspecified addresses as struct in_addr constants, the way it does
in6addr_loopback and in6addr_any for IPv6.  This lack means that in several
places we initialise a local with a macro just so that we can take the
address of an IPv4 loopback or unspecified address.

Provide our own in4addr_any and in4addr_loopback global constants to make
this a bit simpler.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 tcp.c  | 4 ++--
 udp.c  | 5 ++---
 util.c | 3 +++
 util.h | 2 ++
 4 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/tcp.c b/tcp.c
index 052bf7cb..bb914bff 100644
--- a/tcp.c
+++ b/tcp.c
@@ -2944,12 +2944,12 @@ static void tcp_ns_sock_init4(const struct ctx *c, in_port_t port)
 		.port = port,
 		.pif = PIF_SPLICE,
 	};
-	struct in_addr loopback = IN4ADDR_LOOPBACK_INIT;
 	int s;
 
 	ASSERT(c->mode == MODE_PASTA);
 
-	s = sock_l4(c, AF_INET, IPPROTO_TCP, &loopback, NULL, port, tref.u32);
+	s = sock_l4(c, AF_INET, IPPROTO_TCP, &in4addr_loopback, NULL, port,
+		    tref.u32);
 	if (s >= 0)
 		tcp_sock_set_bufsize(c, s);
 	else
diff --git a/udp.c b/udp.c
index 02cb7889..1104f374 100644
--- a/udp.c
+++ b/udp.c
@@ -1012,9 +1012,8 @@ int udp_sock_init(const struct ctx *c, int ns, sa_family_t af,
 			udp_tap_map[V4][uref.port].sock = s < 0 ? -1 : s;
 			udp_splice_init[V4][port].sock = s < 0 ? -1 : s;
 		} else {
-			struct in_addr loopback = IN4ADDR_LOOPBACK_INIT;
-
-			r4 = s = sock_l4(c, AF_INET, IPPROTO_UDP, &loopback,
+			r4 = s = sock_l4(c, AF_INET, IPPROTO_UDP,
+					 &in4addr_loopback,
 					 ifname, port, uref.u32);
 			udp_splice_ns[V4][port].sock = s < 0 ? -1 : s;
 		}
diff --git a/util.c b/util.c
index 8acce233..f1f68a03 100644
--- a/util.c
+++ b/util.c
@@ -30,6 +30,9 @@
 #include "packet.h"
 #include "log.h"
 
+const struct in_addr in4addr_loopback = IN4ADDR_LOOPBACK_INIT;
+const struct in_addr in4addr_any = IN4ADDR_ANY_INIT;
+
 #define IPV6_NH_OPT(nh)							\
 	((nh) == 0   || (nh) == 43  || (nh) == 44  || (nh) == 50  ||	\
 	 (nh) == 51  || (nh) == 60  || (nh) == 135 || (nh) == 139 ||	\
diff --git a/util.h b/util.h
index e0df26c6..4a71904b 100644
--- a/util.h
+++ b/util.h
@@ -125,6 +125,8 @@
 #define IN4ADDR_ANY_INIT \
 	{ .s_addr	= htonl_constant(INADDR_ANY) }
 
+extern const struct in_addr in4addr_loopback;
+extern const struct in_addr in4addr_any;
 
 #define NS_FN_STACK_SIZE	(RLIMIT_STACK_VAL * 1024 / 8)
 int do_clone(int (*fn)(void *), char *stack_area, size_t stack_size, int flags,
-- 
@@ -125,6 +125,8 @@
 #define IN4ADDR_ANY_INIT \
 	{ .s_addr	= htonl_constant(INADDR_ANY) }
 
+extern const struct in_addr in4addr_loopback;
+extern const struct in_addr in4addr_any;
 
 #define NS_FN_STACK_SIZE	(RLIMIT_STACK_VAL * 1024 / 8)
 int do_clone(int (*fn)(void *), char *stack_area, size_t stack_size, int flags,
-- 
2.43.0