Add DHCPv6 support

This is part of u-root#56. For this to be useful the MAC address needs to be read from the interface as well. Signed-off-by: Christian Svensson <bluecmd@google.com>
bluecmd · Sep 25, 2018 · 21f7655 · 21f7655
1 parent 698750b
commit 21f7655
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Showing 2 changed files with 157 additions and 55 deletions.
diff --git a/pkg/bmc/interface.go b/pkg/bmc/interface.go
@@ -0,0 +1,131 @@
+// Copyright 2018 the u-root Authors. All rights reserved
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package bmc
+
+import (
+	"fmt"
+	"log"
+	"math/rand"
+	"time"
+
+	"github.com/vishvananda/netlink"
+	"golang.org/x/sys/unix"
+	"github.com/insomniacslk/dhcp/dhcpv6"
+	"github.com/insomniacslk/dhcp/netboot"
+)
+
+const (
+	interfaceUpTimeout       = 30 * time.Second
+	retryDelay               = 10 * time.Second
+	retryDelaySecondsJitter  = 10
+)
+
+func addIp(cidr string, iface string) error {
+	l, err := netlink.LinkByName(iface)
+	if err != nil {
+		return fmt.Errorf("Unable to get interface %s: %v", iface, err)
+	}
+	addr, err := netlink.ParseAddr(cidr)
+	if err != nil {
+		return fmt.Errorf("netlink.ParseAddr %v: %v", cidr, err)
+	}
+	h, err := netlink.NewHandle(unix.NETLINK_ROUTE)
+	if err != nil {
+		return fmt.Errorf("netlink.NewHandle: %v", err)
+	}
+	defer h.Delete()
+	if err := h.AddrReplace(l, addr); err != nil {
+		return fmt.Errorf("AddrReplace(%v): %v", addr, err)
+	}
+	return nil
+}
+
+func setLinkUp(iface string) error {
+	l, err := netlink.LinkByName(iface)
+	if err != nil {
+		return fmt.Errorf("Unable to get interface %s: %v", iface, err)
+	}
+	h, err := netlink.NewHandle(unix.NETLINK_ROUTE)
+	if err != nil {
+		return fmt.Errorf("netlink.NewHandle: %v", err)
+	}
+	defer h.Delete()
+	if err := h.LinkSetUp(l); err != nil {
+		return fmt.Errorf("handle.LinkSetUp: %v", err)
+	}
+	return nil
+}
+
+func doRetryDelay() {
+	delay := retryDelay + time.Duration(rand.Intn(retryDelaySecondsJitter)) * time.Second
+	log.Printf("Waiting %v before retrying", delay)
+	time.Sleep(delay)
+}
+
+func applyDhcpv6(iface string, reply *dhcpv6.DHCPv6Message) error {
+	log.Printf("reply: %v", reply)
+	return nil
+}
+
+func autoconfigInterface(iface string) {
+	for {
+		_, err := netboot.IfUp(iface, interfaceUpTimeout)
+		if err != nil {
+			log.Printf("Timeout waiting for link up on %s", iface)
+			continue
+		}
+
+		client := dhcpv6.NewClient()
+		conv, err := client.Exchange(iface, nil)
+		if err != nil {
+			log.Printf("DHCPv6 exchange failed for %s: %v", iface, err)
+			doRetryDelay()
+			continue
+		}
+
+		var reply dhcpv6.DHCPv6
+		for _, m := range conv {
+			if m.Type() == dhcpv6.MessageTypeReply {
+				reply = m
+				break
+			}
+		}
+		if reply == nil {
+			log.Printf("No DHCPv6 reply found conversation for %s", iface)
+			doRetryDelay()
+			continue
+		}
+		if err := applyDhcpv6(iface, reply.(*dhcpv6.DHCPv6Message)); err != nil {
+			log.Printf("Failed to apply DHCPv6 configuration for %s: %v", iface, err)
+			doRetryDelay()
+			continue
+		}
+	}
+}
+
+func ConfigureInterfaces() error {
+	unix.Sethostname([]byte("ubmc"))
+
+	// Fun story: if you don't have both IPv4 and IPv6 loopback configured
+	// golang binaries will not bind to :: but to 0.0.0.0 instead.
+	// Isn't that surprising?
+	if err := addIp("127.0.0.1/8", "lo"); err != nil {
+		return err
+	}
+	if err := addIp("::1/32", "lo"); err != nil {
+		return err
+	}
+	if err := setLinkUp("lo"); err != nil {
+		return err
+	}
+
+	// TODO(bluecmd): Read MAC address from NC-SI
+
+	// TODO(bluecmd): Remove when DHCPv6 works
+	addIp("10.0.10.20/24", "eth0")
+
+	go autoconfigInterface("eth0")
+	return nil
+}
diff --git a/pkg/bmc/system.go b/pkg/bmc/system.go
@@ -5,19 +5,22 @@
 package bmc
 
 import (
+	"bytes"
 	"crypto/ecdsa"
 	"crypto/elliptic"
+	crand "crypto/rand"
 	"crypto/x509"
+	"encoding/binary"
 	"encoding/pem"
 	"io"
 	"log"
+	"math/rand"
 	"os"
 	"os/exec"
 	"os/signal"
 	"strings"
 	"syscall"
 
-	"github.com/vishvananda/netlink"
 	"golang.org/x/sys/unix"
 )
 
@@ -57,50 +60,6 @@ func newSshKey() []byte {
 	return pem.EncodeToMemory(&pem.Block{Type: "EC PRIVATE KEY", Bytes: asn1})
 }
 
-func addIp(cidr string, iface string) {
-	l, err := netlink.LinkByName(iface)
-	if err != nil {
-		log.Printf("Unable to get interface %s: %v", iface, err)
-		return
-	}
-
-	addr, err := netlink.ParseAddr(cidr)
-	if err != nil {
-		log.Printf("netlink.ParseAddr %v: %v", cidr, err)
-		return
-	}
-
-	h, err := netlink.NewHandle(unix.NETLINK_ROUTE)
-	if err != nil {
-		log.Printf("netlink.NewHandle: %v", err)
-		return
-	}
-	defer h.Delete()
-	if err := h.AddrReplace(l, addr); err != nil {
-		log.Printf("AddrReplace(%v): %v", addr, err)
-		return
-	}
-}
-
-func setLinkUp(iface string) {
-	l, err := netlink.LinkByName(iface)
-	if err != nil {
-		log.Printf("Unable to get interface %s: %v", iface, err)
-		return
-	}
-
-	h, err := netlink.NewHandle(unix.NETLINK_ROUTE)
-	if err != nil {
-		log.Printf("netlink.NewHandle: %v", err)
-		return
-	}
-	defer h.Delete()
-	if err := h.LinkSetUp(l); err != nil {
-		log.Printf("handle.LinkSetUp: %v", err)
-		return
-	}
-}
-
 func createFile(file string, mode os.FileMode, c []byte) {
 	f, err := os.OpenFile(file, os.O_RDWR|os.O_CREATE, mode)
 	if err != nil {
@@ -140,7 +99,26 @@ func startSsh() {
 	}
 }
 
+func seedRandomGenerator() {
+	b := make([]byte, 8)
+	_, err := crand.Read(b)
+	if err != nil {
+		log.Fatalf("Unable to read random seed, cannot safely continue: %v", err)
+	}
+	buf := bytes.NewReader(b)
+	var seed int64
+	if err := binary.Read(buf, binary.LittleEndian, &seed); err != nil {
+		log.Fatalf("Unable to convert random seed, cannot safely continue: %v", err)
+	}
+	rand.Seed(seed)
+}
+
 func Startup(p Platform) error {
+	// Seed the non-crypto random generator using the crypto one (which is
+	// hardware based). The non-crypto generator is used for random back-off
+	// timers and such, while the crypto one is used for crypto keys.
+	seedRandomGenerator()
+
 	loggers := []io.Writer{os.Stdout}
 	lf, err := os.OpenFile("/tmp/u-bmc.log", os.O_RDWR|os.O_CREATE, 0600)
 	if err != nil {
@@ -151,16 +129,9 @@ func Startup(p Platform) error {
 	}
 
 	log.Printf("Loading system configuration")
-	syscall.Sethostname([]byte("ubmc"))
-
-	// Fun story: if you don't have both IPv4 and IPv6 loopback configured
-	// golang binaries will not bind to :: but to 0.0.0.0 instead.
-	// Isn't that surprising?
-	addIp("127.0.0.1/8", "lo")
-	addIp("::1/32", "lo")
-	addIp("10.0.10.20/24", "eth0")
-	setLinkUp("lo")
-	setLinkUp("eth0")
+	if err := ConfigureInterfaces(); err != nil {
+		log.Printf("Failed to configure interfaces: %v", err)
+	}
 
 	createFile("/etc/passwd", 0644, []byte("root:x:0:0:root:/root:/bbin/elvish"))
 	createFile("/etc/group", 0644, []byte("root:x:0:"))