Merge pull request #10 from pojntfx/support-vlan

Add VLAN support

Makefile

@@ -14,7 +14,7 @@ frontend:
 build: backend frontend
 
 release-backend:
-	CGO_ENABLED=1 go build -ldflags="-extldflags=-static" -tags netgo -o out/release/bofied-backend/bofied-backend.linux-$$(uname -m) cmd/bofied-backend/main.go
+	CGO_ENABLED=0 go build -ldflags="-extldflags=-static" -tags netgo -o out/release/bofied-backend/bofied-backend.linux-$$(uname -m) cmd/bofied-backend/main.go
 
 release-frontend: frontend
 	rm -rf out/release/bofied-frontend

pkg/servers/dhcp.go

@@ -20,6 +20,7 @@ func NewDHCPServer(listenAddress string, advertisedIP string, eventHandler *even
 	return &DHCPServer{
 		UDPServer: UDPServer{
 			listenAddress: listenAddress,
+			advertisedIP:  advertisedIP,
 			handlePacket: func(conn *net.UDPConn, _ *net.UDPAddr, braddr *net.UDPAddr, rawIncomingUDPPacket []byte) (int, error) {
 				return handleDHCPPacket(conn, braddr, rawIncomingUDPPacket, net.ParseIP(advertisedIP).To4(), eventHandler.Emit)
 			},

pkg/servers/proxy_dhcp.go

@@ -16,6 +16,7 @@ func NewProxyDHCPServer(listenAddress string, advertisedIP string, configFileLoc
 	return &ProxyDHCPServer{
 		UDPServer: UDPServer{
 			listenAddress: listenAddress,
+			advertisedIP:  advertisedIP,
 			handlePacket: func(conn *net.UDPConn, raddr *net.UDPAddr, braddr *net.UDPAddr, rawIncomingUDPPacket []byte) (int, error) {
 				return handleProxyDHCPPacket(conn, raddr, braddr, rawIncomingUDPPacket, net.ParseIP(advertisedIP).To4(), configFileLocation, eventHandler.Emit, pureConfig)
 			},

pkg/servers/udp_server.go

@@ -1,8 +1,11 @@
 package servers
 
 import (
+	"errors"
 	"log"
 	"net"
+
+	"github.com/pojntfx/bofied/pkg/utils"
 )
 
 const (
@@ -11,6 +14,7 @@ const (
 
 type UDPServer struct {
 	listenAddress string
+	advertisedIP  string
 	handlePacket  func(conn *net.UDPConn, raddr *net.UDPAddr, braddr *net.UDPAddr, rawIncomingUDPPacket []byte) (int, error)
 }
 
@@ -20,9 +24,53 @@ func (s *UDPServer) ListenAndServe() error {
 	if err != nil {
 		return err
 	}
-	braddr, err := net.ResolveUDPAddr("udp", "255.255.255.255:68")
+
+	aaddr, err := net.ResolveIPAddr("ip", s.advertisedIP)
+	if err != nil {
+		return err
+	}
+
+	// Get all interfaces
+	ifaces, err := net.Interfaces()
+	if err != nil {
+		return err
+	}
+
+	// Find the broadcast address of the interface with the advertised IP
+	broadcastIP := ""
+ifaceLoop:
+	for _, iface := range ifaces {
+		addrs, err := iface.Addrs()
+		if err != nil {
+			return err
+		}
+
+		for _, addr := range addrs {
+			ipnet, ok := addr.(*net.IPNet)
+			if !ok {
+				continue
+			}
+
+			if ipnet.IP.Equal(aaddr.IP) {
+				broadcastIP, err = utils.GetBroadcastAddress(ipnet)
+				if err != nil {
+					return err
+				}
+
+				break ifaceLoop
+			}
+		}
+	}
+
+	// Return if no interface with the advertised IP could be found
+	if broadcastIP == "" {
+		return errors.New("could not resolve broadcast IP")
+	}
+
+	// Construct the broadcast address
+	braddr, err := net.ResolveUDPAddr("udp", net.JoinHostPort(broadcastIP, "68"))
 	if err != nil {
-		log.Fatal(err)
+		return err
 	}
 
 	// Listen

pkg/utils/ip.go

@@ -0,0 +1,26 @@
+package utils
+
+import (
+	"net"
+)
+
+// Based on https://gist.github.com/kotakanbe/d3059af990252ba89a82
+func GetBroadcastAddress(ipnet *net.IPNet) (string, error) {
+	ips := []string{}
+	for ip := ipnet.IP.Mask(ipnet.Mask); ipnet.Contains(ip); inc(ip) {
+		ips = append(ips, ip.String())
+	}
+
+	// The last address is the broadcast address
+	return ips[len(ips)-1], nil
+}
+
+// See http://play.golang.org/p/m8TNTtygK0
+func inc(ip net.IP) {
+	for j := len(ip) - 1; j >= 0; j-- {
+		ip[j]++
+		if ip[j] > 0 {
+			break
+		}
+	}
+}