confile: support the network link string pattern matching

Enable lxc network config support the following type and link:

lxc.network.type = phys
lxc.network.link = eth+

Here, the suffix '+' will trigger a string pattern matching
and when lxc find any network interfaces name prefixed with
"eth" such as "eth0", "eth1", "ethxxxx" and so on, it will
try to move them into the container's namespace; If it didn't
find any matching, it would do nothing for this configure
line.

Signed-off-by: fli <fupan.li@windriver.com>

src/lxc/confile.c

@@ -50,6 +50,12 @@
 #include "network.h"
 #include "lxcseccomp.h"
 
+#if HAVE_IFADDRS_H
+#include <ifaddrs.h>
+#else
+#include <../include/ifaddrs.h>
+#endif
+
 #if HAVE_SYS_PERSONALITY_H
 #include <sys/personality.h>
 #endif
@@ -672,16 +678,85 @@ static int config_network_flags(const char *key, const char *value,
 	return 0;
 }
 
+static int set_network_link(const char *key, const char *value, struct lxc_conf *lxc_conf)
+{
+        struct lxc_netdev *netdev;
+
+        netdev = network_netdev(key, value, &lxc_conf->network);
+        if (!netdev)
+                return -1;
+
+        return network_ifname(&netdev->link, value);
+}
+
+static int create_matched_ifnames(const char *value, struct lxc_conf *lxc_conf)
+{
+	struct ifaddrs *ifaddr, *ifa;
+	const char *type_key = "lxc.network.type";
+	const char *link_key = "lxc.network.link";
+	const char *tmpvalue = "phys";
+	int n, ret = 0;
+
+	if (getifaddrs(&ifaddr) == -1) {
+		SYSERROR("Get network interfaces failed");
+		return -1;
+	}
+
+	for (ifa = ifaddr, n = 0; ifa != NULL; ifa = ifa->ifa_next, n++) {
+		if (!ifa->ifa_addr)
+			continue;
+		if (ifa->ifa_addr->sa_family != AF_PACKET)
+			continue;
+
+		if (!strncmp(value, ifa->ifa_name, strlen(value)-1)) {
+			ret = config_network_type(type_key, tmpvalue, lxc_conf);
+			if (!ret) {
+				ret = set_network_link(link_key, ifa->ifa_name, lxc_conf);
+				if (ret) {
+					ERROR("failed to create matched ifnames");
+					break;
+				}
+			} else {
+				ERROR("failed to create matched ifnames");
+				break;
+			}
+		}
+	}
+
+	freeifaddrs(ifaddr); /* free the dynamic memory */
+	ifaddr = NULL;	    /* prevent use after free */
+
+	return ret;
+}
+
 static int config_network_link(const char *key, const char *value,
 			       struct lxc_conf *lxc_conf)
 {
 	struct lxc_netdev *netdev;
+	struct lxc_list * it;
+	int ret = 0;
 
 	netdev = network_netdev(key, value, &lxc_conf->network);
 	if (!netdev)
 		return -1;
 
-	return network_ifname(&netdev->link, value);
+	if (value[strlen(value) - 1] == '+' && netdev->type == LXC_NET_PHYS) {
+		//get the last network list and remove it.
+		it = lxc_conf->network.prev;
+		if (((struct lxc_netdev *)(it->elem))->type != LXC_NET_PHYS) {
+			ERROR("lxc config cannot support string pattern matching for this link type");
+			return -1;
+		}
+
+		lxc_list_del(it);
+		free(it);
+		ret = create_matched_ifnames(value, lxc_conf);
+
+	} else {
+		ret = network_ifname(&netdev->link, value);
+	}
+
+	return ret;
 }
 
 static int config_network_name(const char *key, const char *value,