util: Make sock_l4() treat empty string ifname like NULL

sock_l4() takes NULL for ifname if you don't want to bind the socket to a
particular interface.  However, for a number of the callers, it's more
natural to use an empty string for that case.  Change sock_l4() to accept
either NULL or an empty string equivalently, and simplify some callers
using that change.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

1 files changed, 4 insertions, 11 deletions

diff --git a/icmp.c b/icmp.c
index d982fda..c82efd0 100644
--- a/icmp.c
+++ b/icmp.c
@@ -187,12 +187,8 @@ int icmp_tap_handler(const struct ctx *c, uint8_t pif, int af,
 		iref.id = id = ntohs(ih->un.echo.id);
 
 		if ((s = icmp_id_map[V4][id].sock) <= 0) {
-			const char *bind_if;
-
-			bind_if = *c->ip4.ifname_out ? c->ip4.ifname_out : NULL;
-
-			s = sock_l4(c, AF_INET, IPPROTO_ICMP,
-				    &c->ip4.addr_out, bind_if, id, iref.u32);
+			s = sock_l4(c, AF_INET, IPPROTO_ICMP, &c->ip4.addr_out,
+				    c->ip4.ifname_out, id, iref.u32);
 			if (s < 0)
 				goto fail_sock;
 			if (s > FD_REF_MAX) {
@@ -237,12 +233,9 @@ int icmp_tap_handler(const struct ctx *c, uint8_t pif, int af,
 
 		iref.id = id = ntohs(ih->icmp6_identifier);
 		if ((s = icmp_id_map[V6][id].sock) <= 0) {
-			const char *bind_if;
-
-			bind_if = *c->ip6.ifname_out ? c->ip6.ifname_out : NULL;
-
 			s = sock_l4(c, AF_INET6, IPPROTO_ICMPV6,
-				    &c->ip6.addr_out, bind_if, id, iref.u32);
+				    &c->ip6.addr_out,
+				    c->ip6.ifname_out, id, iref.u32);
 			if (s < 0)
 				goto fail_sock;
 			if (s > FD_REF_MAX) {