First implementation of DHCP server, compiles but not tested yet.

2018-12-28 17:17:51 +03:00
parent 73f71364b3
commit 8b4a1ca713
9 changed files with 847 additions and 47 deletions
--- a/dhcpd/standalone/main.go
+++ b/dhcpd/standalone/main.go
@@ -0,0 +1,111 @@
+package main
+
+import (
+	"log"
+	"net"
+	"os"
+	"os/signal"
+	"syscall"
+	"time"
+
+	"github.com/AdguardTeam/AdGuardHome/dhcpd"
+	"github.com/krolaw/dhcp4"
+)
+
+func main() {
+	if len(os.Args) < 2 {
+		log.Printf("Usage: %s <interface name>", os.Args[0])
+		os.Exit(64)
+	}
+
+	ifaceName := os.Args[1]
+	present, err := dhcpd.CheckIfOtherDHCPServersPresent(ifaceName)
+	if err != nil {
+		panic(err)
+	}
+	log.Printf("Found DHCP server? %v", present)
+	if present {
+		log.Printf("Will not start DHCP server because there's already running one on the network")
+		os.Exit(1)
+	}
+
+	iface, err := net.InterfaceByName(ifaceName)
+	if err != nil {
+		panic(err)
+	}
+
+	// get ipv4 address of an interface
+	ifaceIPNet := getIfaceIPv4(iface)
+	if ifaceIPNet == nil {
+		panic(err)
+	}
+
+	// append 10 to server's IP address as start
+	start := dhcp4.IPAdd(ifaceIPNet.IP, 10)
+	// lease range is 100 IP's, but TODO: don't go beyond end of subnet mask
+	stop := dhcp4.IPAdd(start, 100)
+
+	server := dhcpd.Server{}
+	config := dhcpd.ServerConfig{
+		InterfaceName: ifaceName,
+		RangeStart:    start.String(),
+		RangeEnd:      stop.String(),
+		SubnetMask:    "255.255.255.0",
+		GatewayIP:     "192.168.7.1",
+	}
+	log.Printf("Starting DHCP server")
+	err = server.Start(&config)
+	if err != nil {
+		panic(err)
+	}
+
+	time.Sleep(time.Second)
+	log.Printf("Stopping DHCP server")
+	err = server.Stop()
+	if err != nil {
+		panic(err)
+	}
+	log.Printf("Starting DHCP server")
+	err = server.Start(&config)
+	if err != nil {
+		panic(err)
+	}
+	log.Printf("Starting DHCP server while it's already running")
+	err = server.Start(&config)
+	if err != nil {
+		panic(err)
+	}
+	log.Printf("Now serving DHCP")
+	signal_channel := make(chan os.Signal)
+	signal.Notify(signal_channel, syscall.SIGINT, syscall.SIGTERM)
+	<-signal_channel
+
+}
+
+// return first IPv4 address of an interface, if there is any
+func getIfaceIPv4(iface *net.Interface) *net.IPNet {
+	ifaceAddrs, err := iface.Addrs()
+	if err != nil {
+		panic(err)
+	}
+
+	for _, addr := range ifaceAddrs {
+		ipnet, ok := addr.(*net.IPNet)
+		if !ok {
+			// not an IPNet, should not happen
+			log.Fatalf("SHOULD NOT HAPPEN: got iface.Addrs() element %s that is not net.IPNet", addr)
+		}
+
+		if ipnet.IP.To4() == nil {
+			log.Printf("Got IP that is not IPv4: %v", ipnet.IP)
+			continue
+		}
+
+		log.Printf("Got IP that is IPv4: %v", ipnet.IP)
+		return &net.IPNet{
+			IP:   ipnet.IP.To4(),
+			Mask: ipnet.Mask,
+		}
+	}
+	return nil
+}