Matt Layher
73f36ca310
* go.mod: initial commit, switch to packet package * dhcp4: introduce temporary type switch for raw/packet transition Signed-off-by: Matt Layher <mdlayher@gmail.com>
73 lines
1.9 KiB
Go
73 lines
1.9 KiB
Go
// Copyright 2018 Google Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package dhcp4_test
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import (
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"log"
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"net"
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"syscall"
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"time"
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"github.com/google/gopacket/layers"
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"github.com/mdlayher/packet"
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"github.com/rtr7/dhcp4"
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)
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func Example() {
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iface, err := net.InterfaceByName("uplink0")
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if err != nil {
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log.Fatal(err)
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}
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xidGen := dhcp4.XIDGenerator(iface.HardwareAddr)
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conn, err := packet.Listen(iface, packet.Datagram, syscall.ETH_P_IP, nil)
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if err != nil {
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log.Fatal(err)
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}
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discover := &layers.DHCPv4{
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Operation: layers.DHCPOpRequest,
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HardwareType: layers.LinkTypeEthernet,
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HardwareLen: uint8(len(layers.EthernetBroadcast)),
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Xid: xidGen(),
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ClientHWAddr: iface.HardwareAddr,
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Options: []layers.DHCPOption{
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dhcp4.MessageTypeOpt(layers.DHCPMsgTypeDiscover),
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dhcp4.HostnameOpt("dhcpprobe"),
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dhcp4.ClientIDOpt(layers.LinkTypeEthernet, iface.HardwareAddr),
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},
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}
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if err := dhcp4.Write(conn, discover); err != nil {
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log.Fatal(err)
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}
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// Display all DHCPOFFER packets received within 5s:
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conn.SetDeadline(time.Now().Add(5 * time.Second))
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for {
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offer, err := dhcp4.Read(conn)
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if err != nil {
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log.Fatal(err)
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}
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if offer == nil {
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continue // not a DHCPv4 packet
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}
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if offer.Xid != discover.Xid {
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continue // broadcast reply for different DHCP transaction
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}
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if !dhcp4.HasMessageType(offer.Options, layers.DHCPMsgTypeOffer) {
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continue
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}
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log.Printf("DHCPOFFER: %+v", offer)
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}
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}
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