[netboot] use rtnl package

After adding the higher-level [rtnl package](https://github.com/jsimonetti/rtnetlink/pull/44)
let's switch to it.

Pending https://github.com/jsimonetti/rtnetlink/pull/50

Signed-off-by: Andrea Barberio <insomniac@slackware.it>

4 files changed, 57 insertions, 248 deletions

diff --git a/netboot/netconf.go b/netboot/netconf.go
index 2e11d38..2ce658b 100644
--- a/netboot/netconf.go
+++ b/netboot/netconf.go
@@ -13,6 +13,7 @@ import (
 	"github.com/insomniacslk/dhcp/dhcpv4"
 	"github.com/insomniacslk/dhcp/dhcpv6"
 	"github.com/jsimonetti/rtnetlink"
+	"github.com/jsimonetti/rtnetlink/rtnl"
 	"github.com/mdlayher/netlink"
 )
 
@@ -138,10 +139,17 @@ func GetNetConfFromPacketv4(d *dhcpv4.DHCPv4) (*NetConf, error) {
 }
 
 // IfUp brings up an interface by name, and waits for it to come up until a timeout expires
-func IfUp(ifname string, timeout time.Duration) (*net.Interface, error) {
+func IfUp(ifname string, timeout time.Duration) (_ *net.Interface, err error) {
 	start := time.Now()
-	var rt RTNL
-	defer rt.Close()
+	rt, err := rtnl.Dial(nil)
+	if err != nil {
+		return nil, err
+	}
+	defer func() {
+		if cerr := rt.Close(); cerr != nil {
+			err = cerr
+		}
+	}()
 	for time.Since(start) < timeout {
 		iface, err := net.InterfaceByName(ifname)
 		if err != nil {
@@ -153,7 +161,7 @@ func IfUp(ifname string, timeout time.Duration) (*net.Interface, error) {
 		//   backward compatibility, routing daemons, dhcp clients can use this
 		//   flag to determine whether they should use the interface.
 		// Source: https://www.kernel.org/doc/Documentation/networking/operstates.txt
-		operState, err := rt.GetLinkState(iface.Index)
+		operState, err := getOperState(iface.Index)
 		if err != nil {
 			return nil, err
 		}
@@ -165,8 +173,7 @@ func IfUp(ifname string, timeout time.Duration) (*net.Interface, error) {
 			return iface, nil
 		}
 		// otherwise try to bring it up
-		err = rt.SetLinkState(iface.Index, true)
-		if err != nil {
+		if err := rt.LinkUp(iface); err != nil {
 			return nil, fmt.Errorf("interface %q: %v can't bring it up: %v", ifname, iface, err)
 		}
 		time.Sleep(10 * time.Millisecond)
@@ -178,16 +185,23 @@ func IfUp(ifname string, timeout time.Duration) (*net.Interface, error) {
 
 // ConfigureInterface configures a network interface with the configuration held by a
 // NetConf structure
-func ConfigureInterface(ifname string, netconf *NetConf) error {
+func ConfigureInterface(ifname string, netconf *NetConf) (err error) {
 	iface, err := net.InterfaceByName(ifname)
 	if err != nil {
 		return err
 	}
-	var rt RTNL
-	defer rt.Close()
+	rt, err := rtnl.Dial(nil)
+	if err != nil {
+		return err
+	}
+	defer func() {
+		if cerr := rt.Close(); err != nil {
+			err = cerr
+		}
+	}()
 	// configure interfaces
 	for _, addr := range netconf.Addresses {
-		if err := rt.SetAddr(iface.Index, addr.IPNet); err != nil {
+		if err := rt.AddrAdd(iface, &addr.IPNet); err != nil {
 			return fmt.Errorf("cannot configure %s on %s: %v", ifname, addr.IPNet, err)
 		}
 	}
@@ -218,7 +232,7 @@ func ConfigureInterface(ifname string, netconf *NetConf) error {
 		// a client would want to add before initiating the DHCP transaction in order not to fail with
 		// ENETUNREACH. If this default route has a specific metric assigned, it doesn't get removed.
 		// The code doesn't remove any other default route (i.e. gw != 0.0.0.0).
-		if err := rt.RouteDel(net.IPv4zero); err != nil {
+		if err := rt.RouteDel(iface, net.IPNet{IP: net.IPv4zero}); err != nil {
 			switch err := err.(type) {
 			case *netlink.OpError:
 				// ignore the error if it's -EEXIST or -ESRCH
@@ -232,7 +246,7 @@ func ConfigureInterface(ifname string, netconf *NetConf) error {
 
 		src := netconf.Addresses[0].IPNet
 		// TODO handle the remaining Routers if more than one
-		if err := rt.RouteAdd(iface.Index, dst, src, netconf.Routers[0]); err != nil {
+		if err := rt.RouteAddSrc(iface, dst, &src, netconf.Routers[0]); err != nil {
 			return fmt.Errorf("could not add gateway %s for src %s dst %s to interface %s: %v", netconf.Routers[0], src, dst, ifname, err)
 		}
 	}
diff --git a/netboot/netconf_integ_test.go b/netboot/netconf_integ_test.go
index e4bad74..5f16782 100644
--- a/netboot/netconf_integ_test.go
+++ b/netboot/netconf_integ_test.go
@@ -3,6 +3,7 @@
 package netboot
 
 import (
+	"net"
 	"testing"
 	"time"
 
@@ -10,17 +11,39 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
+// this assumes that eth0 exists and is configurable
+var ifname = "eth0"
+
 func TestIfUp(t *testing.T) {
-	// this assumes that eth0 exists and is configurable
-	ifname := "eth0"
 	iface, err := IfUp(ifname, 2*time.Second)
 	require.NoError(t, err)
 	assert.Equal(t, ifname, iface.Name)
 }
 
 func TestIfUpTimeout(t *testing.T) {
-	// this assumes that eth0 exists and is configurable
-	ifname := "eth0"
 	_, err := IfUp(ifname, 0*time.Second)
 	require.Error(t, err)
 }
+
+func TestConfigureInterface(t *testing.T) {
+	nc := NetConf{
+		Addresses: []AddrConf{
+			AddrConf{IPNet: net.IPNet{IP: net.ParseIP("10.20.30.40")}},
+		},
+	}
+	err := ConfigureInterface(ifname, &nc)
+	require.NoError(t, err)
+}
+
+func TestConfigureInterfaceWithRouteAndDNS(t *testing.T) {
+	nc := NetConf{
+		Addresses: []AddrConf{
+			AddrConf{IPNet: net.IPNet{IP: net.ParseIP("10.20.30.40")}},
+		},
+		DNSServers:    []net.IP{net.ParseIP("8.8.8.8")},
+		DNSSearchList: []string{"slackware.it"},
+		Routers:       []net.IP{net.ParseIP("10.20.30.254")},
+	}
+	err := ConfigureInterface(ifname, &nc)
+	require.NoError(t, err)
+}
diff --git a/netboot/rtnetlink_linux.go b/netboot/rtnetlink_linux.go
index 949f7e5..41f5b3e 100644
--- a/netboot/rtnetlink_linux.go
+++ b/netboot/rtnetlink_linux.go
@@ -1,162 +1,16 @@
 package netboot
 
-import (
-	"encoding/binary"
-	"net"
+import "github.com/jsimonetti/rtnetlink"
 
-	"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
-	}
+// getOperState returns the operational state for the given interface index.
+func getOperState(iface int) (rtnetlink.OperationalState, error) {
 	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))
+	msg, err := 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
-
-}
diff --git a/netboot/rtnetlink_linux_test.go b/netboot/rtnetlink_linux_test.go
deleted file mode 100644
index 860ea0f..0000000
--- a/netboot/rtnetlink_linux_test.go
+++ /dev/null
@@ -1,82 +0,0 @@
-//+build integration
-
-package netboot
-
-import (
-	"net"
-	"testing"
-
-	"github.com/stretchr/testify/assert"
-	"github.com/stretchr/testify/require"
-	"golang.org/x/sys/unix"
-)
-
-// integration tests that require Linux with a properly working rtnetlink
-// interface, and the existence of an "eth0" interface.
-// WARNING: these tests may improperly configure your network interfaces and
-// routing, so be careful before running them. Privileged access and integration
-// build tag required to run them.
-
-var (
-	testIfname = "eth0"
-)
-
-func TestInit(t *testing.T) {
-	var r RTNL
-	err := r.init()
-	assert.NoError(t, err)
-	require.NotNil(t, r.conn)
-	r.Close()
-}
-
-func TestClose(t *testing.T) {
-	var r RTNL
-	err := r.init()
-	assert.NoError(t, err)
-	require.NotNil(t, r.conn)
-	r.Close()
-	require.Nil(t, r.conn)
-}
-
-func TestGetLinkState(t *testing.T) {
-	var r RTNL
-	defer r.Close()
-
-	iface, err := net.InterfaceByName(testIfname)
-	require.NoError(t, err)
-	_, err = r.GetLinkState(iface.Index)
-	require.NoError(t, err)
-}
-
-func TestSetLinkState(t *testing.T) {
-	var r RTNL
-	defer r.Close()
-
-	iface, err := net.InterfaceByName(testIfname)
-	require.NoError(t, err)
-	err = r.SetLinkState(iface.Index, true)
-	require.NoError(t, err)
-}
-
-func Test_getFamily(t *testing.T) {
-	require.Equal(t, unix.AF_INET, getFamily(net.IPv4zero))
-	require.Equal(t, unix.AF_INET, getFamily(net.IPv4bcast))
-	require.Equal(t, unix.AF_INET, getFamily(net.IPv4allrouter))
-
-	require.Equal(t, unix.AF_INET6, getFamily(net.IPv6zero))
-	require.Equal(t, unix.AF_INET6, getFamily(net.IPv6loopback))
-	require.Equal(t, unix.AF_INET6, getFamily(net.IPv6linklocalallrouters))
-}
-
-func TestSetAddr(t *testing.T) {
-	var r RTNL
-	defer r.Close()
-	iface, err := net.InterfaceByName(testIfname)
-	require.NoError(t, err)
-
-	a := net.IPNet{IP: net.ParseIP("10.0.123.1"), Mask: net.IPv4Mask(255, 255, 255, 0)}
-	err = r.SetAddr(iface.Index, a)
-	require.NoError(t, err)
-	// TODO implement GetAddr to further validate this, and minimize the effect
-	// of concurrent tests that may invalidate this check.
-}