1 files changed, 162 insertions, 0 deletions
diff --git a/netboot/rtnetlink_linux.go b/netboot/rtnetlink_linux.go
new file mode 100644
index 0000000..949f7e5
--- /dev/null
+++ b/netboot/rtnetlink_linux.go
@@ -0,0 +1,162 @@
+package netboot
+
+import (
+	"encoding/binary"
+	"net"
+
+	"github.com/jsimonetti/rtnetlink"
+	"golang.org/x/sys/unix"
+)
+
+// RTNL is a rtnetlink object with a high-level interface.
+type RTNL struct {
+	conn *rtnetlink.Conn
+}
+
+func (r *RTNL) init() error {
+	if r.conn != nil {
+		return nil
+	}
+	conn, err := rtnetlink.Dial(nil)
+	if err != nil {
+		return err
+	}
+	r.conn = conn
+	return nil
+}
+
+// Close closes the netlink connection. Must be called to avoid leaks!
+func (r *RTNL) Close() {
+	if r.conn != nil {
+		r.conn.Close()
+		r.conn = nil
+	}
+}
+
+// GetLinkState returns the operational state for the given interface index.
+func (r *RTNL) GetLinkState(iface int) (rtnetlink.OperationalState, error) {
+	if err := r.init(); err != nil {
+		return 0, err
+	}
+	msg, err := r.conn.Link.Get(uint32(iface))
+	if err != nil {
+		return 0, err
+	}
+	return msg.Attributes.OperationalState, nil
+}
+
+// SetLinkState sets the operational state up or down for the given interface
+// index.
+func (r *RTNL) SetLinkState(iface int, up bool) error {
+	if err := r.init(); err != nil {
+		return err
+	}
+	var state uint32
+	if up {
+		state = unix.IFF_UP
+	}
+	msg := rtnetlink.LinkMessage{
+		Family: unix.AF_UNSPEC,
+		Type:   unix.ARPHRD_NETROM,
+		Index:  uint32(iface),
+		Flags:  state,
+		Change: unix.IFF_UP,
+	}
+	if err := r.conn.Link.Set(&msg); err != nil {
+		return err
+	}
+	return nil
+}
+
+func getFamily(ip net.IP) int {
+	if ip.To4() != nil {
+		return unix.AF_INET
+	}
+	return unix.AF_INET6
+}
+
+// SetAddr sets the interface address.
+func (r *RTNL) SetAddr(iface int, a net.IPNet) error {
+	if err := r.init(); err != nil {
+		return err
+	}
+	ones, _ := a.Mask.Size()
+	msg := rtnetlink.AddressMessage{
+		Family:       uint8(getFamily(a.IP)),
+		PrefixLength: uint8(ones),
+		// TODO detect the right scope to set, or get it as input argument
+		Scope: unix.RT_SCOPE_UNIVERSE,
+		Index: uint32(iface),
+		Attributes: rtnetlink.AddressAttributes{
+			Address: a.IP,
+			Local:   a.IP,
+		},
+	}
+	if a.IP.To4() != nil {
+		// Broadcast is only required for IPv4
+		ip := make(net.IP, net.IPv4len)
+		binary.BigEndian.PutUint32(
+			ip,
+			binary.BigEndian.Uint32(a.IP.To4())|
+				^binary.BigEndian.Uint32(net.IP(a.Mask).To4()))
+		msg.Attributes.Broadcast = ip
+	}
+	if err := r.conn.Address.New(&msg); err != nil {
+		return err
+	}
+	return nil
+}
+
+// RouteDel deletes a route to the given destination
+func (r *RTNL) RouteDel(dst net.IP) error {
+	if err := r.init(); err != nil {
+		return err
+	}
+	msg := rtnetlink.RouteMessage{
+		Family: uint8(getFamily(dst)),
+		Table:  unix.RT_TABLE_MAIN,
+		// TODO make this configurable?
+		Protocol: unix.RTPROT_UNSPEC,
+		// TODO make this configurable?
+		Scope: unix.RT_SCOPE_NOWHERE,
+		Type:  unix.RTN_UNSPEC,
+		Attributes: rtnetlink.RouteAttributes{
+			Dst: dst,
+		},
+	}
+	if err := r.conn.Route.Delete(&msg); err != nil {
+		return err
+	}
+	return nil
+}
+
+// RouteAdd adds a route to dst, from src (if set), via gw.
+func (r *RTNL) RouteAdd(iface int, dst, src net.IPNet, gw net.IP) error {
+	if err := r.init(); err != nil {
+		return err
+	}
+	dstLen, _ := dst.Mask.Size()
+	srcLen, _ := src.Mask.Size()
+	msg := rtnetlink.RouteMessage{
+		Family: uint8(getFamily(dst.IP)),
+		Table:  unix.RT_TABLE_MAIN,
+		// TODO make this configurable?
+		Protocol: unix.RTPROT_BOOT,
+		// TODO make this configurable?
+		Scope:     unix.RT_SCOPE_UNIVERSE,
+		Type:      unix.RTN_UNICAST,
+		DstLength: uint8(dstLen),
+		SrcLength: uint8(srcLen),
+		Attributes: rtnetlink.RouteAttributes{
+			Dst:      dst.IP,
+			Src:      src.IP,
+			Gateway:  gw,
+			OutIface: uint32(iface),
+		},
+	}
+	if err := r.conn.Route.Add(&msg); err != nil {
+		return err
+	}
+	return nil
+
+}