lkl-upstream: add lkl_ifname_to_ifindex()

Signed-off-by: Hajime Tazaki <thehajime@gmail.com>

tools/lkl/include/lkl.h

@@ -363,6 +363,14 @@ int lkl_set_ipv6_gateway(void* addr);
 int lkl_if_set_ipv6_gateway(int ifindex, void *addr,
 		unsigned int netmask_len, void *gw_addr);
 
+/**
+ * lkl_ifname_to_ifindex - obtain ifindex of an interface by name
+ *
+ * @name - string of an interface
+ * @returns - return an integer of ifindex if no error
+ */
+int lkl_ifname_to_ifindex(const char *name);
+
 /**
  * lkl_netdev - host network device handle, defined in lkl_host.h.
  */

tools/lkl/lib/net.c

@@ -17,6 +17,24 @@ static inline int ifindex_to_name(int sock, struct lkl_ifreq *ifr, int ifindex)
 	return lkl_sys_ioctl(sock, LKL_SIOCGIFNAME, (long)ifr);
 }
 
+int lkl_ifname_to_ifindex(const char *name)
+{
+	struct lkl_ifreq ifr;
+	int fd, ret;
+
+	fd = lkl_sys_socket(LKL_AF_INET, LKL_SOCK_DGRAM, 0);
+	if (fd < 0)
+		return fd;
+
+	strcpy(ifr.lkl_ifr_name, name);
+
+	ret = lkl_sys_ioctl(fd, LKL_SIOCGIFINDEX, (long)&ifr);
+	if (ret < 0)
+		return ret;
+
+	return ifr.lkl_ifr_ifindex;
+}
+
 int lkl_if_up(int ifindex)
 {
 	struct lkl_ifreq ifr;