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cf15d5bbc6
These are no longer needed as these are now part of a module. Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
92 lines
2.3 KiB
Go
92 lines
2.3 KiB
Go
package l2disco
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import (
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"context"
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"fmt"
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"net"
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"slices"
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"github.com/containerd/log"
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"golang.org/x/net/ipv6"
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)
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var naTemplate = []byte{
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0x88, // Type (136=NA)
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0x00, // Code (always 0)
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0x00, 0x00, // Checksum (filled in by the kernel)
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0x20, // Flags, Router=0, Solicited=0, Override=1
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0x00, 0x00, 0x00, // Reserved
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // Target IP
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0x02, // Option - target link layer address
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0x01, // Option length (32)
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // Target MAC
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}
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type UnsolNA struct {
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pkt []byte
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pc *ipv6.PacketConn
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cm *ipv6.ControlMessage
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}
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// NewUnsolNA returns a pointer to an object that can send unsolicited Neighbour
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// Advertisements for ip and mac.
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// https://datatracker.ietf.org/doc/html/rfc4861#section-4.4
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func NewUnsolNA(ctx context.Context, ip net.IP, mac net.HardwareAddr, ifIndex int) (*UnsolNA, error) {
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// Open a socket ... it'll be bound to an address but the address doesn't matter,
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// no packets are to be received, and a source address is supplied when sending.
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netPC, err := net.ListenPacket("ip6:ipv6-icmp", "::1")
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if err != nil {
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return nil, err
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}
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pc := ipv6.NewPacketConn(netPC)
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// Block incoming packets.
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f := ipv6.ICMPFilter{}
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f.SetAll(true)
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if err := pc.SetICMPFilter(&f); err != nil {
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log.G(ctx).WithError(err).Errorf("failed to set ICMP filter")
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}
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cm := &ipv6.ControlMessage{
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// https://datatracker.ietf.org/doc/html/rfc4861#section-3.1
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// By setting the Hop Limit to 255, Neighbor Discovery is immune to
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// off-link senders that accidentally or intentionally send ND
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// messages.
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HopLimit: 255,
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Src: ip,
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IfIndex: ifIndex,
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}
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pkt := slices.Clone(naTemplate)
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copy(pkt[8:24], ip)
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copy(pkt[26:32], mac)
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return &UnsolNA{
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pkt: pkt,
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pc: pc,
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cm: cm,
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}, nil
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}
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// Send sends an unsolicited ARP message.
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func (un *UnsolNA) Send() error {
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n, err := un.pc.WriteTo(un.pkt, un.cm, &net.IPAddr{IP: net.IPv6linklocalallnodes})
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if err != nil {
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return err
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}
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if n != len(un.pkt) {
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return fmt.Errorf("failed to send packet: len:%d sent:%d", len(un.pkt), n)
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}
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return nil
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}
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// Close releases resources.
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func (un *UnsolNA) Close() error {
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if un.pc != nil {
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err := un.pc.Close()
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un.pc = 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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