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Add missing icmpv6.go
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parent
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80
src/core/icmpv6.go
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80
src/core/icmpv6.go
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package core
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// The ICMPv6 module implements functions to easily create ICMPv6
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// packets. These functions, when mixed with the built-in Go IPv6
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// and ICMP libraries, can be used to send control messages back
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// to the host. Examples include:
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// - NDP messages, when running in TAP mode
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// - Packet Too Big messages, when packets exceed the session MTU
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// - Destination Unreachable messages, when a session prohibits
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// incoming traffic
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import (
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"encoding/binary"
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"net"
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"golang.org/x/net/icmp"
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"golang.org/x/net/ipv6"
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)
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type ICMPv6 struct{}
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// Marshal returns the binary encoding of h.
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func ipv6Header_Marshal(h *ipv6.Header) ([]byte, error) {
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b := make([]byte, 40)
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b[0] |= byte(h.Version) << 4
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b[0] |= byte(h.TrafficClass) >> 4
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b[1] |= byte(h.TrafficClass) << 4
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b[1] |= byte(h.FlowLabel >> 16)
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b[2] = byte(h.FlowLabel >> 8)
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b[3] = byte(h.FlowLabel)
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binary.BigEndian.PutUint16(b[4:6], uint16(h.PayloadLen))
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b[6] = byte(h.NextHeader)
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b[7] = byte(h.HopLimit)
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copy(b[8:24], h.Src)
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copy(b[24:40], h.Dst)
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return b, nil
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}
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// Creates an ICMPv6 packet based on the given icmp.MessageBody and other
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// parameters, complete with IP headers only, which can be written directly to
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// a TUN adapter, or called directly by the CreateICMPv6L2 function when
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// generating a message for TAP adapters.
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func CreateICMPv6(dst net.IP, src net.IP, mtype ipv6.ICMPType, mcode int, mbody icmp.MessageBody) ([]byte, error) {
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// Create the ICMPv6 message
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icmpMessage := icmp.Message{
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Type: mtype,
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Code: mcode,
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Body: mbody,
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}
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// Convert the ICMPv6 message into []byte
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icmpMessageBuf, err := icmpMessage.Marshal(icmp.IPv6PseudoHeader(src, dst))
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if err != nil {
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return nil, err
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}
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// Create the IPv6 header
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ipv6Header := ipv6.Header{
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Version: ipv6.Version,
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NextHeader: 58,
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PayloadLen: len(icmpMessageBuf),
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HopLimit: 255,
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Src: src,
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Dst: dst,
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}
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// Convert the IPv6 header into []byte
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ipv6HeaderBuf, err := ipv6Header_Marshal(&ipv6Header)
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if err != nil {
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return nil, err
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}
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// Construct the packet
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responsePacket := make([]byte, ipv6.HeaderLen+ipv6Header.PayloadLen)
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copy(responsePacket[:ipv6.HeaderLen], ipv6HeaderBuf)
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copy(responsePacket[ipv6.HeaderLen:], icmpMessageBuf)
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// Send it back
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return responsePacket, nil
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}
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