Compare commits
3 Commits
13677eaf54
...
d11855bfd0
| Author | SHA1 | Date | |
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d11855bfd0 | ||
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7d3a40987b | ||
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001517eb15 |
330
cmd/root.go
Normal file
330
cmd/root.go
Normal file
@@ -0,0 +1,330 @@
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package cmd
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import (
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"bytes"
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"encoding/binary"
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"fmt"
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"net"
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"os"
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"unsafe"
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"github.com/adrianokf/go-dhcp/pkg/leases"
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"github.com/adrianokf/go-dhcp/pkg/messages"
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"github.com/adrianokf/go-dhcp/pkg/types"
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"github.com/spf13/cobra"
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"go.uber.org/zap"
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)
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var listenInterface string
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var manager = leases.NewLeaseManager()
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var magic = [4]byte{0x63, 0x82, 0x53, 0x63}
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func parseOptions(data []byte) messages.Options {
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s := zap.S()
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i := 0
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options := make(messages.Options)
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out:
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for i < len(data) {
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code := messages.OptionCode(data[i])
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switch code {
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case messages.OptionEnd:
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s.Debug("Found END option at offset ", i)
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break out
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case messages.OptionPad:
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s.Debug("Found padding option at offset ", i)
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i += 1
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continue
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}
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size := int(data[i+1])
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payload := data[i+2 : i+2+size]
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s.Debugf("code=%d, size=%d, payload=%x", code, size, payload)
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options[code] = messages.Option{Code: code, Data: data[i+1 : i+2+size]}
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i += size + 2
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}
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s.Debugf("Parsed options: ", options)
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return options
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}
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func prepareOffer(request messages.DhcpMessage, lease leases.Lease) messages.DhcpMessage {
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var sname [64]byte
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var file [128]byte
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var siaddr types.Ipv4Addr
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copy(sname[:], "go-dhcp-server")
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copy(siaddr[:], net.IPv4(10, 0, 0, 1).To4())
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dhcp := messages.DhcpMessage{
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Op: messages.BOOTREPLY,
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Htype: 1, // Ethernet
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Hlen: 6, // Ethernet address length
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Hops: 0,
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Secs: 0,
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Flags: request.Flags,
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Xid: lease.TransactionId,
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Siaddr: siaddr,
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Ciaddr: [4]byte{0, 0, 0, 0},
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Yiaddr: lease.Address,
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Giaddr: request.Giaddr,
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Chaddr: request.Chaddr,
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Magic: magic,
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Sname: sname,
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File: file,
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}
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return dhcp
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}
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func prepareAck(request messages.DhcpMessage, lease leases.Lease) messages.DhcpMessage {
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var sname [64]byte
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var file [128]byte
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copy(sname[:], "go-dhcp-server")
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dhcp := messages.DhcpMessage{
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Op: messages.BOOTREPLY,
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Htype: 1, // Ethernet
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Hlen: 6, // Ethernet address length
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Hops: 0,
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Secs: 0,
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Flags: 0,
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Xid: request.Xid,
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Siaddr: lease.Address,
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Ciaddr: request.Ciaddr,
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Yiaddr: lease.Address,
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Giaddr: request.Giaddr,
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Chaddr: request.Chaddr,
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Magic: magic,
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Sname: sname,
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File: file,
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}
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return dhcp
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}
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// sendMessage transmits a DHCP message with options via a UDP connection
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// The end option (code 255) is automatically appended and does not need to
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// be passed explicitly.
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func sendMessage(conn *net.UDPConn, message messages.DhcpMessage, options []messages.Option) error {
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buf := make([]byte, 0)
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w := bytes.NewBuffer(buf)
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err := binary.Write(w, binary.BigEndian, message)
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if err != nil {
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return err
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}
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for _, v := range options {
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err = w.WriteByte(byte(v.Code))
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if err != nil {
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return err
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}
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_, err = w.Write(v.Data)
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if err != nil {
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return err
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}
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}
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// Automatically add END option, so the caller doesn't
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// need to specificy it for every invocation.
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err = w.WriteByte(byte(messages.OptionEnd))
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if err != nil {
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return err
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}
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msg := w.Bytes()
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zap.S().Debug("Msg", msg)
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_, err = conn.Write(msg)
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if err != nil {
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return err
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}
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return nil
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}
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func handleOffer(dhcp messages.DhcpMessage, remote *net.UDPAddr) error {
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s := zap.S()
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lease, err := manager.Request(dhcp.Xid, dhcp.Chaddr)
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if err != nil {
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panic(err)
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}
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offer := prepareOffer(dhcp, *lease)
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localAddr, _ := net.ResolveUDPAddr("udp", "172.17.0.1:68")
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clientAddr, _ := net.ResolveUDPAddr("udp", "255.255.255.255:68")
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conn, err := net.DialUDP("udp", localAddr, clientAddr)
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if err != nil {
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panic(err)
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}
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defer conn.Close()
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s.Info("Sending DHCPOFFER...")
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options := []messages.Option{
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{
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Code: messages.OptionDHCPMessageType,
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Data: []byte{1, byte(messages.MessageTypeOffer)},
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},
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}
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sendMessage(conn, offer, options)
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return nil
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}
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func handleAck(dhcp messages.DhcpMessage, remote *net.UDPAddr) error {
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s := zap.S()
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lease, err := manager.Lookup(dhcp.Xid)
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if err != nil {
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panic(err)
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}
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ack := prepareAck(dhcp, *lease)
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options := []messages.Option{
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{
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Code: messages.OptionDHCPMessageType,
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Data: []byte{1, byte(messages.MessageTypeAck)},
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},
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{
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Code: messages.OptionIPAddressLeaseTime,
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Data: append([]byte{4}, u32tob(3600)...),
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},
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}
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s.Debug("Options: ", options)
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localAddr, _ := net.ResolveUDPAddr("udp", "172.17.0.1:68")
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clientAddr, _ := net.ResolveUDPAddr("udp", "255.255.255.255:68")
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conn, err := net.DialUDP("udp", localAddr, clientAddr)
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if err != nil {
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panic(err)
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}
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defer conn.Close()
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s.Info("Sending DHCPACK")
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sendMessage(conn, ack, options)
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lease, err = manager.Request(dhcp.Xid, dhcp.Chaddr)
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if err != nil {
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return err
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}
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s.Debug("Found lease", lease)
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return nil
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}
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func handleMsg(data []byte, remote *net.UDPAddr) {
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s := zap.S()
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s.Debugf("Connection from client %v", remote.IP)
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var dhcp messages.DhcpMessage
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reader := bytes.NewReader(data)
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binary.Read(reader, binary.BigEndian, &dhcp)
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dhcp.Debug(s)
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if dhcp.Magic != [4]byte{0x63, 0x82, 0x53, 0x63} {
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panic("Invalid DHCP magic field")
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}
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optDataOffset := int(unsafe.Sizeof(dhcp))
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optData := data[optDataOffset:]
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s.Debug("Raw options data:", optData)
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options := parseOptions(optData)
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dhcpMsgType := options[messages.OptionDHCPMessageType]
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s.Info("DHCP message type ", dhcpMsgType)
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switch messages.MessageType(dhcpMsgType.Data[1]) {
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case messages.MessageTypeDiscover:
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go handleOffer(dhcp, remote)
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case messages.MessageTypeRequest:
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go handleAck(dhcp, remote)
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}
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}
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func runServer(interfaceName string) {
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var addr *net.UDPAddr
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if interfaceName == "all" {
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zap.L().Debug("Listening on all interfaces")
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addr, _ = net.ResolveUDPAddr("udp4", ":67")
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} else {
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zap.S().Debugf("Listening on interface %s", interfaceName)
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iface, err := net.InterfaceByName(interfaceName)
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if err != nil {
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panic(err)
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}
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addrs, err := iface.Addrs()
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if err != nil {
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panic(err)
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}
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// Find first IPv4 address associated with the interface
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var ip net.IP = nil
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for _, ifaddr := range addrs {
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switch a := ifaddr.(type) {
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case *net.IPAddr:
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ip = a.IP
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case *net.IPNet:
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ip = a.IP
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}
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ip = ip.To4()
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if ip != nil {
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break
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}
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}
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if ip == nil {
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zap.S().Panicf("No IPv4 address associated with interface %s", interfaceName)
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}
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fmt.Printf("%+v\n", ip)
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addr, _ = net.ResolveUDPAddr("udp4", ip.String()+":67")
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}
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conn, err := net.ListenUDP("udp4", addr)
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if err != nil {
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panic(err)
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}
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defer conn.Close()
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zap.S().Infof("Listening for incoming connections on %s", addr.String())
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for {
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buf := make([]byte, 1024)
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rlen, remote, err := conn.ReadFrom(buf[:])
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if err != nil {
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panic(err)
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}
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// Do stuff with the read bytes
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remoteAddr, ok := remote.(*net.UDPAddr)
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if !ok {
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zap.S().Warn("Not a valid remote IP address: ", remote)
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continue
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}
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go handleMsg(buf[0:rlen], remoteAddr)
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}
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}
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var rootCmd = &cobra.Command{
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Use: "go-dhcp",
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Short: "go-dhcp is a simple DHCP server written in Go",
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Run: func(cmd *cobra.Command, args []string) {
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runServer(listenInterface)
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},
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}
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func init() {
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// Set up logging
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logger, _ := zap.NewDevelopment()
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defer logger.Sync() // flushes buffer, if any
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zap.ReplaceGlobals(logger)
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rootCmd.PersistentFlags().StringVarP(&listenInterface, "interface", "i", "all", "Interface to listen on")
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}
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func Execute() {
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if err := rootCmd.Execute(); err != nil {
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fmt.Println(err)
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os.Exit(1)
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}
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}
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@@ -1,16 +1,9 @@
|
||||
package main
|
||||
package cmd
|
||||
|
||||
import (
|
||||
"encoding/binary"
|
||||
"net"
|
||||
)
|
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|
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func int2ip(nn uint32) net.IP {
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ip := make(net.IP, 4)
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binary.BigEndian.PutUint32(ip, nn)
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return ip
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}
|
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|
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func u32tob(u uint32) []byte {
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buf := make([]byte, 4)
|
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binary.BigEndian.PutUint32(buf, u)
|
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12
go.mod
12
go.mod
@@ -2,9 +2,15 @@ module github.com/adrianokf/go-dhcp
|
||||
|
||||
go 1.17
|
||||
|
||||
require go.uber.org/zap v1.21.0
|
||||
require go.uber.org/zap v1.26.0
|
||||
|
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require (
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||||
go.uber.org/atomic v1.7.0 // indirect
|
||||
go.uber.org/multierr v1.6.0 // indirect
|
||||
github.com/inconshreveable/mousetrap v1.1.0 // indirect
|
||||
github.com/spf13/pflag v1.0.5 // indirect
|
||||
)
|
||||
|
||||
require (
|
||||
github.com/spf13/cobra v1.8.0
|
||||
go.uber.org/atomic v1.11.0 // indirect
|
||||
go.uber.org/multierr v1.11.0 // indirect
|
||||
)
|
||||
|
||||
17
go.sum
17
go.sum
@@ -1,8 +1,11 @@
|
||||
github.com/benbjohnson/clock v1.1.0 h1:Q92kusRqC1XV2MjkWETPvjJVqKetz1OzxZB7mHJLju8=
|
||||
github.com/benbjohnson/clock v1.1.0/go.mod h1:J11/hYXuz8f4ySSvYwY0FKfm+ezbsZBKZxNJlLklBHA=
|
||||
github.com/cpuguy83/go-md2man/v2 v2.0.3/go.mod h1:tgQtvFlXSQOSOSIRvRPT7W67SCa46tRHOmNcaadrF8o=
|
||||
github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
|
||||
github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
|
||||
github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
|
||||
github.com/inconshreveable/mousetrap v1.1.0 h1:wN+x4NVGpMsO7ErUn/mUI3vEoE6Jt13X2s0bqwp9tc8=
|
||||
github.com/inconshreveable/mousetrap v1.1.0/go.mod h1:vpF70FUmC8bwa3OWnCshd2FqLfsEA9PFc4w1p2J65bw=
|
||||
github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORNo=
|
||||
github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
|
||||
github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
|
||||
@@ -10,19 +13,32 @@ github.com/pkg/errors v0.8.1 h1:iURUrRGxPUNPdy5/HRSm+Yj6okJ6UtLINN0Q9M4+h3I=
|
||||
github.com/pkg/errors v0.8.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
|
||||
github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
|
||||
github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
|
||||
github.com/russross/blackfriday/v2 v2.1.0/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQDYRxCVz55jmeOWTM=
|
||||
github.com/spf13/cobra v1.8.0 h1:7aJaZx1B85qltLMc546zn58BxxfZdR/W22ej9CFoEf0=
|
||||
github.com/spf13/cobra v1.8.0/go.mod h1:WXLWApfZ71AjXPya3WOlMsY9yMs7YeiHhFVlvLyhcho=
|
||||
github.com/spf13/pflag v1.0.5 h1:iy+VFUOCP1a+8yFto/drg2CJ5u0yRoB7fZw3DKv/JXA=
|
||||
github.com/spf13/pflag v1.0.5/go.mod h1:McXfInJRrz4CZXVZOBLb0bTZqETkiAhM9Iw0y3An2Bg=
|
||||
github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
|
||||
github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
|
||||
github.com/stretchr/testify v1.7.0 h1:nwc3DEeHmmLAfoZucVR881uASk0Mfjw8xYJ99tb5CcY=
|
||||
github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
|
||||
github.com/stretchr/testify v1.8.1 h1:w7B6lhMri9wdJUVmEZPGGhZzrYTPvgJArz7wNPgYKsk=
|
||||
github.com/yuin/goldmark v1.3.5/go.mod h1:mwnBkeHKe2W/ZEtQ+71ViKU8L12m81fl3OWwC1Zlc8k=
|
||||
go.uber.org/atomic v1.7.0 h1:ADUqmZGgLDDfbSL9ZmPxKTybcoEYHgpYfELNoN+7hsw=
|
||||
go.uber.org/atomic v1.7.0/go.mod h1:fEN4uk6kAWBTFdckzkM89CLk9XfWZrxpCo0nPH17wJc=
|
||||
go.uber.org/atomic v1.11.0 h1:ZvwS0R+56ePWxUNi+Atn9dWONBPp/AUETXlHW0DxSjE=
|
||||
go.uber.org/atomic v1.11.0/go.mod h1:LUxbIzbOniOlMKjJjyPfpl4v+PKK2cNJn91OQbhoJI0=
|
||||
go.uber.org/goleak v1.1.11 h1:wy28qYRKZgnJTxGxvye5/wgWr1EKjmUDGYox5mGlRlI=
|
||||
go.uber.org/goleak v1.1.11/go.mod h1:cwTWslyiVhfpKIDGSZEM2HlOvcqm+tG4zioyIeLoqMQ=
|
||||
go.uber.org/goleak v1.2.0 h1:xqgm/S+aQvhWFTtR0XK3Jvg7z8kGV8P4X14IzwN3Eqk=
|
||||
go.uber.org/multierr v1.6.0 h1:y6IPFStTAIT5Ytl7/XYmHvzXQ7S3g/IeZW9hyZ5thw4=
|
||||
go.uber.org/multierr v1.6.0/go.mod h1:cdWPpRnG4AhwMwsgIHip0KRBQjJy5kYEpYjJxpXp9iU=
|
||||
go.uber.org/multierr v1.11.0 h1:blXXJkSxSSfBVBlC76pxqeO+LN3aDfLQo+309xJstO0=
|
||||
go.uber.org/multierr v1.11.0/go.mod h1:20+QtiLqy0Nd6FdQB9TLXag12DsQkrbs3htMFfDN80Y=
|
||||
go.uber.org/zap v1.21.0 h1:WefMeulhovoZ2sYXz7st6K0sLj7bBhpiFaud4r4zST8=
|
||||
go.uber.org/zap v1.21.0/go.mod h1:wjWOCqI0f2ZZrJF/UufIOkiC8ii6tm1iqIsLo76RfJw=
|
||||
go.uber.org/zap v1.26.0 h1:sI7k6L95XOKS281NhVKOFCUNIvv9e0w4BF8N3u+tCRo=
|
||||
go.uber.org/zap v1.26.0/go.mod h1:dtElttAiwGvoJ/vj4IwHBS/gXsEu/pZ50mUIRWuG0so=
|
||||
golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
|
||||
golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
|
||||
golang.org/x/lint v0.0.0-20190930215403-16217165b5de/go.mod h1:6SW0HCj/g11FgYtHlgUYUwCkIfeOF89ocIRzGO/8vkc=
|
||||
@@ -55,3 +71,4 @@ gopkg.in/yaml.v2 v2.2.8/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
|
||||
gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
|
||||
gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b h1:h8qDotaEPuJATrMmW04NCwg7v22aHH28wwpauUhK9Oo=
|
||||
gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
|
||||
gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
|
||||
|
||||
278
main.go
278
main.go
@@ -1,283 +1,9 @@
|
||||
package main
|
||||
|
||||
import (
|
||||
"bytes"
|
||||
"encoding/binary"
|
||||
"net"
|
||||
"unsafe"
|
||||
|
||||
"go.uber.org/zap"
|
||||
"github.com/adrianokf/go-dhcp/cmd"
|
||||
)
|
||||
|
||||
var manager = NewLeaseManager()
|
||||
|
||||
var leases []Lease = make([]Lease, 0)
|
||||
|
||||
func (dhcp DhcpMessage) Debug(s *zap.SugaredLogger) {
|
||||
s.Debugf("op=%x, htype=%x, hlen=%x, hops=%x", dhcp.Op, dhcp.Htype, dhcp.Hlen, dhcp.Hops)
|
||||
s.Debugf("xid=%x", dhcp.Xid)
|
||||
s.Debugf("secs=%d, flags=%x", dhcp.Secs, dhcp.Flags)
|
||||
|
||||
s.Debugf("ciaddr=%x", dhcp.Ciaddr)
|
||||
s.Debugf("siaddr=%x", dhcp.Siaddr)
|
||||
s.Debugf("giaddr=%x", dhcp.Giaddr)
|
||||
s.Debugf("chaddr=%x", dhcp.Chaddr)
|
||||
|
||||
s.Debugf("sname=%s", string(dhcp.Sname[:]))
|
||||
s.Debugf("file=%s", string(dhcp.File[:]))
|
||||
s.Debugf("magic=%x", dhcp.Magic)
|
||||
}
|
||||
|
||||
func parseOptions(data []byte) Options {
|
||||
s := zap.S()
|
||||
i := 0
|
||||
|
||||
options := make(Options)
|
||||
|
||||
out:
|
||||
for i < len(data) {
|
||||
code := OptionCode(data[i])
|
||||
switch code {
|
||||
case OptionEnd:
|
||||
s.Debug("Found END option at offset ", i)
|
||||
break out
|
||||
|
||||
case OptionPad:
|
||||
s.Debug("Found padding option at offset ", i)
|
||||
i += 1
|
||||
continue
|
||||
}
|
||||
|
||||
size := int(data[i+1])
|
||||
payload := data[i+2 : i+2+size]
|
||||
|
||||
s.Debugf("code=%d, size=%d, payload=%x", code, size, payload)
|
||||
options[code] = Option{Code: code, Data: data[i+1 : i+2+size]}
|
||||
i += size + 2
|
||||
}
|
||||
|
||||
s.Debugf("Parsed options: ", options)
|
||||
return options
|
||||
}
|
||||
|
||||
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,
|
||||
Htype: 1, // Ethernet
|
||||
Hlen: 6, // Ethernet address length
|
||||
Hops: 0,
|
||||
Secs: 0,
|
||||
Flags: request.Flags,
|
||||
Xid: lease.TransactionId,
|
||||
Siaddr: siaddr,
|
||||
Ciaddr: [4]byte{0, 0, 0, 0},
|
||||
Yiaddr: lease.Address,
|
||||
Giaddr: request.Giaddr,
|
||||
Chaddr: request.Chaddr,
|
||||
Magic: magic,
|
||||
Sname: sname,
|
||||
File: file,
|
||||
}
|
||||
return dhcp
|
||||
}
|
||||
|
||||
func prepareAck(request DhcpMessage, lease Lease) DhcpMessage {
|
||||
var sname [64]byte
|
||||
var file [128]byte
|
||||
copy(sname[:], "go-dhcp-server")
|
||||
|
||||
dhcp := DhcpMessage{
|
||||
Op: BOOTREPLY,
|
||||
Htype: 1, // Ethernet
|
||||
Hlen: 6, // Ethernet address length
|
||||
Hops: 0,
|
||||
Secs: 0,
|
||||
Flags: 0,
|
||||
Xid: request.Xid,
|
||||
Siaddr: lease.Address,
|
||||
Ciaddr: request.Ciaddr,
|
||||
Yiaddr: lease.Address,
|
||||
Giaddr: request.Giaddr,
|
||||
Chaddr: request.Chaddr,
|
||||
Magic: magic,
|
||||
Sname: sname,
|
||||
File: file,
|
||||
}
|
||||
return dhcp
|
||||
}
|
||||
|
||||
// sendMessage transmits a DHCP message with options via a UDP connection
|
||||
// The end option (code 255) is automatically appended and does not need to
|
||||
// be passed explicitly.
|
||||
func sendMessage(conn *net.UDPConn, message DhcpMessage, options []Option) error {
|
||||
buf := make([]byte, 0)
|
||||
w := bytes.NewBuffer(buf)
|
||||
err := binary.Write(w, binary.BigEndian, message)
|
||||
if err != nil {
|
||||
return err
|
||||
}
|
||||
|
||||
for _, v := range options {
|
||||
err = w.WriteByte(byte(v.Code))
|
||||
if err != nil {
|
||||
return err
|
||||
}
|
||||
_, err = w.Write(v.Data)
|
||||
if err != nil {
|
||||
return err
|
||||
}
|
||||
}
|
||||
|
||||
// Automatically add END option, so the caller doesn't
|
||||
// need to specificy it for every invocation.
|
||||
err = w.WriteByte(byte(OptionEnd))
|
||||
if err != nil {
|
||||
return err
|
||||
}
|
||||
|
||||
msg := w.Bytes()
|
||||
zap.S().Debug("Msg", msg)
|
||||
_, err = conn.Write(msg)
|
||||
if err != nil {
|
||||
return err
|
||||
}
|
||||
|
||||
return nil
|
||||
}
|
||||
|
||||
func handleOffer(dhcp DhcpMessage, remote *net.UDPAddr) error {
|
||||
s := zap.S()
|
||||
|
||||
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)
|
||||
if err != nil {
|
||||
panic(err)
|
||||
}
|
||||
defer conn.Close()
|
||||
|
||||
s.Info("Sending DHCPOFFER...")
|
||||
options := []Option{
|
||||
{
|
||||
Code: OptionDHCPMessageType,
|
||||
Data: []byte{1, byte(MessageTypeOffer)},
|
||||
},
|
||||
}
|
||||
sendMessage(conn, offer, options)
|
||||
return nil
|
||||
}
|
||||
|
||||
func handleAck(dhcp DhcpMessage, remote *net.UDPAddr) error {
|
||||
s := zap.S()
|
||||
|
||||
lease, err := manager.Lookup(dhcp.Xid)
|
||||
if err != nil {
|
||||
panic(err)
|
||||
}
|
||||
|
||||
ack := prepareAck(dhcp, *lease)
|
||||
|
||||
options := []Option{
|
||||
{
|
||||
Code: OptionDHCPMessageType,
|
||||
Data: []byte{1, byte(MessageTypeAck)},
|
||||
},
|
||||
{
|
||||
Code: OptionIPAddressLeaseTime,
|
||||
Data: append([]byte{4}, u32tob(3600)...),
|
||||
},
|
||||
}
|
||||
s.Debug("Options: ", options)
|
||||
|
||||
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)
|
||||
if err != nil {
|
||||
panic(err)
|
||||
}
|
||||
defer conn.Close()
|
||||
|
||||
s.Info("Sending DHCPACK")
|
||||
sendMessage(conn, ack, options)
|
||||
|
||||
lease, err = manager.Request(dhcp.Xid, dhcp.Chaddr)
|
||||
if err != nil {
|
||||
return err
|
||||
}
|
||||
s.Debug("Found lease", lease)
|
||||
return nil
|
||||
}
|
||||
|
||||
func handleMsg(data []byte, remote *net.UDPAddr) {
|
||||
s := zap.S()
|
||||
|
||||
s.Debugf("Connection from client %v", remote.IP)
|
||||
|
||||
var dhcp DhcpMessage
|
||||
reader := bytes.NewReader(data)
|
||||
binary.Read(reader, binary.BigEndian, &dhcp)
|
||||
dhcp.Debug(s)
|
||||
|
||||
if dhcp.Magic != [4]byte{0x63, 0x82, 0x53, 0x63} {
|
||||
panic("Invalid DHCP magic field")
|
||||
}
|
||||
|
||||
optDataOffset := int(unsafe.Sizeof(dhcp))
|
||||
optData := data[optDataOffset:]
|
||||
s.Debug("Raw options data:", optData)
|
||||
|
||||
options := parseOptions(optData)
|
||||
dhcpMsgType := options[OptionDHCPMessageType]
|
||||
s.Info("DHCP message type ", dhcpMsgType)
|
||||
|
||||
switch MessageType(dhcpMsgType.Data[1]) {
|
||||
case MessageTypeDiscover:
|
||||
go handleOffer(dhcp, remote)
|
||||
|
||||
case MessageTypeRequest:
|
||||
go handleAck(dhcp, remote)
|
||||
}
|
||||
}
|
||||
|
||||
func main() {
|
||||
// Set up logging
|
||||
logger, _ := zap.NewDevelopment()
|
||||
defer logger.Sync() // flushes buffer, if any
|
||||
zap.ReplaceGlobals(logger)
|
||||
|
||||
addr, _ := net.ResolveUDPAddr("udp4", ":67")
|
||||
conn, err := net.ListenUDP("udp4", addr)
|
||||
if err != nil {
|
||||
panic(err)
|
||||
}
|
||||
defer conn.Close()
|
||||
|
||||
zap.L().Info("Listening for incoming connections")
|
||||
|
||||
for {
|
||||
buf := make([]byte, 1024)
|
||||
rlen, remote, err := conn.ReadFrom(buf[:])
|
||||
if err != nil {
|
||||
panic(err)
|
||||
}
|
||||
|
||||
// Do stuff with the read bytes
|
||||
remoteAddr, ok := remote.(*net.UDPAddr)
|
||||
if !ok {
|
||||
zap.S().Warn("Not a valid remote IP address: ", remote)
|
||||
continue
|
||||
}
|
||||
go handleMsg(buf[0:rlen], remoteAddr)
|
||||
}
|
||||
cmd.Execute()
|
||||
}
|
||||
|
||||
@@ -1,32 +1,48 @@
|
||||
package main
|
||||
package leases
|
||||
|
||||
import (
|
||||
"errors"
|
||||
"fmt"
|
||||
"time"
|
||||
|
||||
"github.com/adrianokf/go-dhcp/pkg/types"
|
||||
"go.uber.org/zap"
|
||||
)
|
||||
|
||||
type LeaseState uint8
|
||||
|
||||
const (
|
||||
Offered LeaseState = iota
|
||||
Requested
|
||||
)
|
||||
|
||||
type Lease struct {
|
||||
TransactionId types.TxId
|
||||
TTL time.Time
|
||||
State LeaseState
|
||||
ClientAddr types.HwAddr
|
||||
Address types.Ipv4Addr
|
||||
}
|
||||
|
||||
type ILeaseManager interface {
|
||||
Request(xid TxId, clientAddr HwAddr) (*Lease, error)
|
||||
Request(xid types.TxId, clientAddr types.HwAddr) (*Lease, error)
|
||||
Release(l Lease) error
|
||||
Lookup(xid TxId) error
|
||||
Lookup(xid types.TxId) error
|
||||
}
|
||||
|
||||
type LeaseManager struct {
|
||||
leases map[TxId]Lease
|
||||
leases map[types.TxId]Lease
|
||||
count byte
|
||||
}
|
||||
|
||||
func NewLeaseManager() *LeaseManager {
|
||||
m := &LeaseManager{
|
||||
leases: make(map[TxId]Lease),
|
||||
leases: make(map[types.TxId]Lease),
|
||||
}
|
||||
return m
|
||||
}
|
||||
|
||||
func (m *LeaseManager) Request(xid TxId, clientAddr HwAddr) (*Lease, error) {
|
||||
func (m *LeaseManager) Request(xid types.TxId, clientAddr types.HwAddr) (*Lease, error) {
|
||||
zap.S().Debugf("LeaseManager.Request(%v, %v)", xid, clientAddr)
|
||||
|
||||
if m.count > 254 {
|
||||
@@ -58,7 +74,7 @@ func (m LeaseManager) Release(l Lease) error {
|
||||
return nil
|
||||
}
|
||||
|
||||
func (m LeaseManager) Lookup(xid TxId) (*Lease, error) {
|
||||
func (m LeaseManager) Lookup(xid types.TxId) (*Lease, error) {
|
||||
lease, found := m.leases[xid]
|
||||
if found {
|
||||
return &lease, nil
|
||||
@@ -1,9 +1,15 @@
|
||||
package main
|
||||
package messages
|
||||
|
||||
import (
|
||||
"time"
|
||||
"github.com/adrianokf/go-dhcp/pkg/types"
|
||||
"go.uber.org/zap"
|
||||
)
|
||||
|
||||
type Message interface {
|
||||
Marshal() ([]byte, error)
|
||||
Unmarshal([]byte) (Message, error)
|
||||
}
|
||||
|
||||
type OptionCode byte
|
||||
|
||||
// DHCPv4 Options
|
||||
@@ -195,40 +201,35 @@ const (
|
||||
MessageTypeInform
|
||||
)
|
||||
|
||||
type LeaseState uint8
|
||||
type TxId [4]byte
|
||||
type Ipv4Addr [4]byte
|
||||
type HwAddr [16]byte
|
||||
|
||||
var magic = [4]byte{0x63, 0x82, 0x53, 0x63}
|
||||
|
||||
type DhcpMessage struct {
|
||||
Op DhcpOp
|
||||
Htype MessageType
|
||||
Hlen byte
|
||||
Hops byte
|
||||
Xid TxId
|
||||
Xid types.TxId
|
||||
Secs uint16
|
||||
Flags uint16
|
||||
Ciaddr Ipv4Addr
|
||||
Yiaddr Ipv4Addr
|
||||
Siaddr Ipv4Addr
|
||||
Giaddr Ipv4Addr
|
||||
Chaddr HwAddr
|
||||
Ciaddr types.Ipv4Addr
|
||||
Yiaddr types.Ipv4Addr
|
||||
Siaddr types.Ipv4Addr
|
||||
Giaddr types.Ipv4Addr
|
||||
Chaddr types.HwAddr
|
||||
Sname [64]byte
|
||||
File [128]byte
|
||||
Magic [4]byte
|
||||
}
|
||||
|
||||
const (
|
||||
Offered LeaseState = iota
|
||||
Requested
|
||||
)
|
||||
func (dhcp DhcpMessage) Debug(s *zap.SugaredLogger) {
|
||||
s.Debugf("op=%x, htype=%x, hlen=%x, hops=%x", dhcp.Op, dhcp.Htype, dhcp.Hlen, dhcp.Hops)
|
||||
s.Debugf("xid=%x", dhcp.Xid)
|
||||
s.Debugf("secs=%d, flags=%x", dhcp.Secs, dhcp.Flags)
|
||||
|
||||
type Lease struct {
|
||||
TransactionId TxId
|
||||
TTL time.Time
|
||||
State LeaseState
|
||||
ClientAddr HwAddr
|
||||
Address Ipv4Addr
|
||||
s.Debugf("ciaddr=%x", dhcp.Ciaddr)
|
||||
s.Debugf("siaddr=%x", dhcp.Siaddr)
|
||||
s.Debugf("giaddr=%x", dhcp.Giaddr)
|
||||
s.Debugf("chaddr=%x", dhcp.Chaddr)
|
||||
|
||||
s.Debugf("sname=%s", string(dhcp.Sname[:]))
|
||||
s.Debugf("file=%s", string(dhcp.File[:]))
|
||||
s.Debugf("magic=%x", dhcp.Magic)
|
||||
}
|
||||
@@ -1,4 +1,4 @@
|
||||
package main
|
||||
package messages
|
||||
|
||||
type Option struct {
|
||||
Code OptionCode
|
||||
5
pkg/types/types.go
Normal file
5
pkg/types/types.go
Normal file
@@ -0,0 +1,5 @@
|
||||
package types
|
||||
|
||||
type TxId [4]byte
|
||||
type Ipv4Addr [4]byte
|
||||
type HwAddr [16]byte
|
||||
Reference in New Issue
Block a user