1 files changed, 114 insertions, 0 deletions
diff --git a/internal/pkg/network/iface.go b/internal/pkg/network/iface.go
new file mode 100644
index 0000000..b2a57bd
--- /dev/null
+++ b/internal/pkg/network/iface.go
@@ -0,0 +1,114 @@
+package network
+
+import (
+	"errors"
+	"net"
+	"syscall"
+
+	"github.com/vishvananda/netlink"
+)
+
+//GetDefaultGateway return default gateway of the network namespace
+func GetDefaultGateway() (string, error) {
+	routes, err := netlink.RouteList(nil, syscall.AF_INET)
+	if err != nil {
+		return "", err
+	}
+
+	for _, route := range routes {
+		if route.Dst == nil || route.Dst.String() == "0.0.0.0/0" {
+			if route.Gw.To4() == nil {
+				return "", errors.New("Found default route but could not determine gateway")
+			}
+			return route.Gw.To4().String(), nil
+		}
+	}
+
+	return "", errors.New("Unable to find default route")
+}
+
+// GetDefaultGatewayInterface return default gateway interface link
+func GetDefaultGatewayInterface() (*net.Interface, error) {
+	routes, err := netlink.RouteList(nil, syscall.AF_INET)
+	if err != nil {
+		return nil, err
+	}
+
+	for _, route := range routes {
+		if route.Dst == nil || route.Dst.String() == "0.0.0.0/0" {
+			if route.LinkIndex <= 0 {
+				return nil, errors.New("Found default route but could not determine interface")
+			}
+			return net.InterfaceByIndex(route.LinkIndex)
+		}
+	}
+
+	return nil, errors.New("Unable to find default route")
+}
+
+func getIfaceAddrs(iface *net.Interface) ([]netlink.Addr, error) {
+
+	link := &netlink.Device{
+		netlink.LinkAttrs{
+			Index: iface.Index,
+		},
+	}
+
+	return netlink.AddrList(link, syscall.AF_INET)
+}
+
+//GetInterfaceIP4Addr return IP4addr of a interface
+func GetInterfaceIP4Addr(iface *net.Interface) (netlink.Addr, error) {
+	addrs, err := getIfaceAddrs(iface)
+	if err != nil {
+		return netlink.Addr{}, err
+	}
+
+	// prefer non link-local addr
+	var ll netlink.Addr
+
+	for _, addr := range addrs {
+		if addr.IP.To4() == nil {
+			continue
+		}
+
+		if addr.IP.IsGlobalUnicast() {
+			return addr, nil
+		}
+
+		if addr.IP.IsLinkLocalUnicast() {
+			ll = addr
+		}
+	}
+
+	if ll.IP.To4() != nil {
+		// didn't find global but found link-local. it'll do.
+		return ll, nil
+	}
+
+	return netlink.Addr{}, errors.New("No IPv4 address found for given interface")
+}
+
+//GetHostNetwork return default gateway interface network
+func GetHostNetwork() (string, error) {
+
+	iface, err := GetDefaultGatewayInterface()
+	if err != nil {
+		log.Error(err, "error in gettting default gateway interface")
+		return "", err
+	}
+
+	ipv4addr, err := GetInterfaceIP4Addr(iface)
+	if err != nil {
+		log.Error(err, "error in gettting default gateway interface IPv4 address")
+		return "", err
+	}
+
+	_, ipv4Net, err := net.ParseCIDR(ipv4addr.IPNet.String())
+	if err != nil {
+		log.Error(err, "error in gettting default gateway interface network")
+		return "", err
+	}
+
+	return ipv4Net.String(), nil
+}