network: clear whole networks

When users specify

lxc.network.<n>

we remove the whole network from the networks list.

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

src/lxc/confile.c

@@ -4294,8 +4294,7 @@ get_network_config_ops(const char *key, struct lxc_conf *lxc_conf, ssize_t *idx)
 		}
 
 		/* This, of course is utterly nonsensical on so many levels, but
-		* better
+		 * better safe than sorry.
-		* safe than sorry.
 		 */
 		if (tmpidx == UINT_MAX) {
 			SYSERROR(
@@ -4355,9 +4354,31 @@ static int set_config_network_nic(const char *key, const char *value,
 static int clr_config_network_nic(const char *key, struct lxc_conf *lxc_conf,
 				  void *data)
 {
+	const char *idxstring;
 	struct lxc_config_t *config;
 	struct lxc_netdev *netdev;
-	ssize_t idx = -1;
+	ssize_t idx;
+
+	/* If we get passed "lxc.network.<n>" we clear the whole network. */
+	if (strncmp("lxc.network.", key, 12))
+		return -1;
+
+	idxstring = key + 12;
+	/* The left conjunct is pretty self-explanatory. The right conjunct
+	 * checks whether the two pointers are equal. If they are we now that
+	 * this is not a key that is namespaced any further and so we are
+	 * supposed to clear the whole network.
+	 */
+	if (isdigit(*idxstring) && (strrchr(key, '.') == (idxstring - 1))) {
+		unsigned int rmnetdevidx;
+
+		if (lxc_safe_uint(idxstring, &rmnetdevidx) < 0)
+			return -1;
+
+		/* Remove network from network list. */
+		lxc_remove_nic_by_idx(lxc_conf, rmnetdevidx);
+		return 0;
+	}
 
 	config = get_network_config_ops(key, lxc_conf, &idx);
 	if (!config || idx < 0)

src/lxc/confile_utils.c

@@ -293,3 +293,47 @@ void lxc_log_configured_netdevs(const struct lxc_conf *conf)
 			TRACE("downscript: %s", netdev->downscript);
 	}
 }
+
+bool lxc_remove_nic_by_idx(struct lxc_conf *conf, unsigned int idx)
+{
+	struct lxc_list *cur, *it, *next;
+	struct lxc_netdev *netdev;
+	bool found = false;
+
+	lxc_list_for_each_safe(cur, &conf->network, next) {
+		netdev = cur->elem;
+		if (netdev->idx != idx)
+			continue;
+
+		lxc_list_del(cur);
+		found = true;
+		break;
+	}
+
+	if (!found)
+		return false;
+
+	free(netdev->link);
+	free(netdev->name);
+	if (netdev->type == LXC_NET_VETH)
+		free(netdev->priv.veth_attr.pair);
+	free(netdev->upscript);
+	free(netdev->hwaddr);
+	free(netdev->mtu);
+	free(netdev->ipv4_gateway);
+	free(netdev->ipv6_gateway);
+	lxc_list_for_each_safe(it, &netdev->ipv4, next) {
+		lxc_list_del(it);
+		free(it->elem);
+		free(it);
+	}
+	lxc_list_for_each_safe(it, &netdev->ipv6, next) {
+		lxc_list_del(it);
+		free(it->elem);
+		free(it);
+	}
+	free(netdev);
+	free(cur);
+
+	return true;
+}

src/lxc/confile_utils.h

@@ -33,5 +33,6 @@ extern struct lxc_netdev *lxc_find_netdev_by_idx(struct lxc_conf *conf,
 extern struct lxc_netdev *lxc_get_netdev_by_idx(struct lxc_conf *conf,
 						unsigned int idx);
 extern void lxc_log_configured_netdevs(const struct lxc_conf *conf);
+extern bool lxc_remove_nic_by_idx(struct lxc_conf *conf, unsigned int idx);
 
 #endif /* __LXC_CONFILE_UTILS_H */