Matt Layher
61 lines
1.6 KiB
Go
61 lines
1.6 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
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import (
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"net"
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"github.com/google/gopacket"
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"github.com/google/gopacket/layers"
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"github.com/mdlayher/packet"
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)
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var ip, udp = func() (*layers.IPv4, *layers.UDP) {
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ip := &layers.IPv4{
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Version: 4,
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TTL: 255,
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Protocol: layers.IPProtocolUDP,
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SrcIP: net.ParseIP("0.0.0.0"),
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DstIP: net.ParseIP("255.255.255.255"),
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}
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udp := &layers.UDP{
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SrcPort: 68,
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DstPort: 67,
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}
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udp.SetNetworkLayerForChecksum(ip)
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return ip, udp
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}()
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// Write encodes pkt as an IPv4 packet to pc.
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func Write(pc net.PacketConn, pkt *layers.DHCPv4) error {
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buf := gopacket.NewSerializeBuffer()
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// TODO: padding: add 0 bytes until at least 272 bytes
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// probably in gopacket itself, see also https://github.com/google/gopacket/issues/361
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gopacket.SerializeLayers(buf,
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gopacket.SerializeOptions{
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FixLengths: true,
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ComputeChecksums: true,
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},
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ip,
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udp,
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pkt,
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)
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_, err := pc.WriteTo(buf.Bytes(), &packet.Addr{
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HardwareAddr: layers.EthernetBroadcast,
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})
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return err
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}
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