dhclient: bring interface up

dhclient/main.go

@@ -4,6 +4,7 @@ import (
 	"flag"
 	"log"
 	"net"
+	"time"
 
 	"github.com/insomniacslk/dhcp/dhcpv4"
 	"github.com/insomniacslk/dhcp/dhcpv6"
@@ -13,13 +14,14 @@ import (
 var (
 	ver    = flag.Int("v", 6, "IP version to use")
 	ifname = flag.String("i", "eth0", "Interface name")
+	dryrun = flag.Bool("dryrun", false, "Do not change network configuration")
 	debug  = flag.Bool("d", false, "Print debug output")
 )
 
-func dhclient6(ifname string, verbose bool) error {
+func dhclient6(ifname string, verbose bool) (*netboot.NetConf, error) {
 	llAddr, err := dhcpv6.GetLinkLocalAddr(ifname)
 	if err != nil {
-		return err
+		return nil, err
 	}
 	laddr := net.UDPAddr{
 		IP:   llAddr,
@@ -41,18 +43,14 @@ func dhclient6(ifname string, verbose bool) error {
 		}
 	}
 	if err != nil {
-		return err
+		return nil, err
 	}
 	// extract the network configuration
 	netconf, _, err := netboot.ConversationToNetconf(conv)
-	if err != nil {
-		return err
-	}
-	// configure the interface
-	return netboot.ConfigureInterface(ifname, netconf)
+	return netconf, err
 }
 
-func dhclient4(ifname string, verbose bool) error {
+func dhclient4(ifname string, verbose bool) (*netboot.NetConf, error) {
 	client := dhcpv4.NewClient()
 	conv, err := client.Exchange(ifname, nil)
 	if verbose {
@@ -61,27 +59,39 @@ func dhclient4(ifname string, verbose bool) error {
 		}
 	}
 	if err != nil {
-		return err
+		return nil, err
 	}
 	// extract the network configuration
 	netconf, _, err := netboot.ConversationToNetconfv4(conv)
-	if err != nil {
-		return err
-	}
-	// configure the interface
-	return netboot.ConfigureInterface(ifname, netconf)
+	return netconf, err
 }
 
 func main() {
 	flag.Parse()
 
-	var err error
+	var (
+		err     error
+		netconf *netboot.NetConf
+	)
+	// bring interface up
+	_, err = netboot.IfUp(*ifname, 5*time.Second)
+	if err != nil {
+		log.Fatal(err)
+	}
 	if *ver == 6 {
-		err = dhclient6(*ifname, *debug)
+		netconf, err = dhclient6(*ifname, *debug)
 	} else {
-		err = dhclient4(*ifname, *debug)
+		netconf, err = dhclient4(*ifname, *debug)
 	}
 	if err != nil {
 		log.Fatal(err)
 	}
+	// configure the interface
+	if *debug {
+		log.Printf("Setting network configuration:")
+		log.Printf("%+v", netconf)
+	}
+	if err := netboot.ConfigureInterface(*ifname, netconf); err != nil {
+		log.Fatal(err)
+	}
 }