adriano/go-dhcp
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feat: Working lease manager

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This commit is contained in:
Adrian Rumpold
2022-02-20 12:47:29 +01:00
parent 9f83d6f3f5
commit 234582e586
3 changed files with 110 additions and 31 deletions
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50
main.go
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@@ -4,12 +4,13 @@ import (
"bytes"
"encoding/binary"
"net"
"time"
"unsafe"
"go.uber.org/zap"
)
var manager = NewLeaseManager()
var leases []Lease = make([]Lease, 0)
func (dhcp DhcpMessage) Debug(s *zap.SugaredLogger) {
@@ -59,10 +60,12 @@ out:
return options
}
func prepareOffer(request DhcpMessage) DhcpMessage {
func prepareOffer(request DhcpMessage, lease Lease) DhcpMessage {
var sname [64]byte
var file [128]byte
var siaddr Ipv4Addr
copy(sname[:], "go-dhcp-server")
copy(siaddr[:], net.IPv4(10, 0, 0, 1).To4())
dhcp := DhcpMessage{
Op: BOOTREPLY,
@@ -71,20 +74,20 @@ func prepareOffer(request DhcpMessage) DhcpMessage {
Hops: 0,
Secs: 0,
Flags: request.Flags,
Xid: request.Xid,
Siaddr: binary.BigEndian.Uint32(net.IPv4(10, 0, 0, 1).To4()),
Ciaddr: 0,
Yiaddr: binary.BigEndian.Uint32(net.IPv4(10, 0, 0, 2).To4()),
Xid: lease.TransactionId,
Siaddr: siaddr,
Ciaddr: [4]byte{0, 0, 0, 0},
Yiaddr: lease.Address,
Giaddr: request.Giaddr,
Chaddr: request.Chaddr,
Magic: [4]byte{0x63, 0x82, 0x53, 0x63},
Magic: magic,
Sname: sname,
File: file,
}
return dhcp
}
func prepareAck(request DhcpMessage) DhcpMessage {
func prepareAck(request DhcpMessage, lease Lease) DhcpMessage {
var sname [64]byte
var file [128]byte
copy(sname[:], "go-dhcp-server")
@@ -97,12 +100,12 @@ func prepareAck(request DhcpMessage) DhcpMessage {
Secs: 0,
Flags: 0,
Xid: request.Xid,
Siaddr: binary.BigEndian.Uint32(net.IPv4(10, 0, 0, 1).To4()),
Siaddr: lease.Address,
Ciaddr: request.Ciaddr,
Yiaddr: binary.BigEndian.Uint32(net.IPv4(10, 0, 0, 2).To4()),
Yiaddr: lease.Address,
Giaddr: request.Giaddr,
Chaddr: request.Chaddr,
Magic: [4]byte{0x63, 0x82, 0x53, 0x63},
Magic: magic,
Sname: sname,
File: file,
}
@@ -151,7 +154,11 @@ func sendMessage(conn *net.UDPConn, message DhcpMessage, options []Option) error
func handleOffer(dhcp DhcpMessage, remote *net.UDPAddr) error {
s := zap.S()
offer := prepareOffer(dhcp)
lease, err := manager.Request(dhcp.Xid, dhcp.Chaddr)
if err != nil {
panic(err)
}
offer := prepareOffer(dhcp, *lease)
localAddr, _ := net.ResolveUDPAddr("udp", "172.17.0.1:68")
clientAddr, _ := net.ResolveUDPAddr("udp", "255.255.255.255:68")
conn, err := net.DialUDP("udp", localAddr, clientAddr)
@@ -174,7 +181,12 @@ func handleOffer(dhcp DhcpMessage, remote *net.UDPAddr) error {
func handleAck(dhcp DhcpMessage, remote *net.UDPAddr) error {
s := zap.S()
ack := prepareAck(dhcp)
lease, err := manager.Lookup(dhcp.Xid)
if err != nil {
panic(err)
}
ack := prepareAck(dhcp, *lease)
options := []Option{
{
@@ -199,15 +211,11 @@ func handleAck(dhcp DhcpMessage, remote *net.UDPAddr) error {
s.Info("Sending DHCPACK")
sendMessage(conn, ack, options)
lease := Lease{
TransactionId: ack.Xid,
TTL: time.Now().Add(1 * time.Hour),
State: Requested,
ClientAddr: ack.Chaddr,
Address: int2ip(ack.Yiaddr),
lease, err = manager.Request(dhcp.Xid, dhcp.Chaddr)
if err != nil {
return err
}
leases = append(leases, lease)
s.Debug("Found lease", lease)
return nil
}