allow lxc.network.pair to specify host-side name for veth interface

Currently we allocate veth device with random name on host side,
so that things like firewall rules or accounting does not work
at all.  Fix this by recognizing yet anothe keyword to specify
the host-side device name: lxc.network.pair, and use it instead
of random name if specified.

Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
Signed-off-by: Daniel Lezcano <dlezcano@fr.ibm.com>

3 files changed, 25 insertions, 4 deletions

diff --git a/src/lxc/conf.c b/src/lxc/conf.c
index 9c3a558..523270e 100644
--- a/src/lxc/conf.c
+++ b/src/lxc/conf.c
@@ -829,14 +829,19 @@ int lxc_conf_init(struct lxc_conf *conf)
 
 static int instanciate_veth(struct lxc_netdev *netdev)
 {
-	char veth1[IFNAMSIZ];
+	char veth1buf[IFNAMSIZ], *veth1;
 	char veth2[IFNAMSIZ];
 	int ret = -1;
 
-	snprintf(veth1, sizeof(veth1), "vethXXXXXX");
-	snprintf(veth2, sizeof(veth2), "vethXXXXXX");
+	if (netdev->pair)
+		veth1 = netdev->pair;
+	else {
+		snprintf(veth1buf, sizeof(veth1buf), "vethXXXXXX");
+		mktemp(veth1buf);
+		veth1 = veth1buf;
+	}
 
-	mktemp(veth1);
+	snprintf(veth2, sizeof(veth2), "vethXXXXXX");
 	mktemp(veth2);
 
 	if (!strlen(veth1) || !strlen(veth2)) {
diff --git a/src/lxc/conf.h b/src/lxc/conf.h
index 0b8d732..bb38206 100644
--- a/src/lxc/conf.h
+++ b/src/lxc/conf.h
@@ -73,6 +73,7 @@ struct lxc_route6 {
  * Defines a structure to configure a network device
  * @link   : lxc.network.link, name of bridge or host iface to attach if any
  * @name   : lxc.network.name, name of iface on the container side
+ * @pair   : lxc.network.pair, name of host-side iface in case of veth etc
  * @flags  : flag of the network device (IFF_UP, ... )
  * @ipv4   : a list of ipv4 addresses to be set on the network device
  * @ipv6   : a list of ipv6 addresses to be set on the network device
@@ -83,6 +84,7 @@ struct lxc_netdev {
 	int ifindex;
 	char *link;
 	char *name;
+	char *pair;
 	char *hwaddr;
 	char *mtu;
 	struct lxc_list ipv4;
diff --git a/src/lxc/confile.c b/src/lxc/confile.c
index 39a8e2c..3a9a86d 100644
--- a/src/lxc/confile.c
+++ b/src/lxc/confile.c
@@ -49,6 +49,7 @@ static int config_network_type(const char *, char *, struct lxc_conf *);
 static int config_network_flags(const char *, char *, struct lxc_conf *);
 static int config_network_link(const char *, char *, struct lxc_conf *);
 static int config_network_name(const char *, char *, struct lxc_conf *);
+static int config_network_pair(const char *, char *, struct lxc_conf *);
 static int config_network_hwaddr(const char *, char *, struct lxc_conf *);
 static int config_network_mtu(const char *, char *, struct lxc_conf *);
 static int config_network_ipv4(const char *, char *, struct lxc_conf *);
@@ -73,6 +74,7 @@ static struct config config[] = {
 	{ "lxc.network.flags",  config_network_flags  },
 	{ "lxc.network.link",   config_network_link   },
 	{ "lxc.network.name",   config_network_name   },
+	{ "lxc.network.pair",   config_network_pair   },
 	{ "lxc.network.hwaddr", config_network_hwaddr },
 	{ "lxc.network.mtu",    config_network_mtu    },
 	{ "lxc.network.ipv4",   config_network_ipv4   },
@@ -221,6 +223,18 @@ static int config_network_name(const char *key, char *value,
 	return network_ifname(&netdev->name, value);
 }
 
+static int config_network_pair(const char *key, 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->pair, value);
+}
+
 static int config_network_hwaddr(const char *key, char *value,
 				 struct lxc_conf *lxc_conf)
 {