mirror of
https://github.com/yggdrasil-network/yggdrasil-go.git
synced 2025-11-04 11:15:07 +03:00
Refactoring: move tuntap and icmpv6 into separate package
This commit is contained in:
Neil Alexander
parent
67c670ab4c
commit
0b494a8255
20 changed files with 307 additions and 240 deletions
331
src/tuntap/icmpv6.go
Normal file
331
src/tuntap/icmpv6.go
Normal file
|
|
@ -0,0 +1,331 @@
|
|||
package tuntap
|
||||
|
||||
// The ICMPv6 module implements functions to easily create ICMPv6
|
||||
// packets. These functions, when mixed with the built-in Go IPv6
|
||||
// and ICMP libraries, can be used to send control messages back
|
||||
// to the host. Examples include:
|
||||
// - NDP messages, when running in TAP mode
|
||||
// - Packet Too Big messages, when packets exceed the session MTU
|
||||
// - Destination Unreachable messages, when a session prohibits
|
||||
// incoming traffic
|
||||
|
||||
import (
|
||||
"encoding/binary"
|
||||
"errors"
|
||||
"net"
|
||||
"time"
|
||||
|
||||
"golang.org/x/net/icmp"
|
||||
"golang.org/x/net/ipv6"
|
||||
|
||||
"github.com/yggdrasil-network/yggdrasil-go/src/address"
|
||||
)
|
||||
|
||||
type macAddress [6]byte
|
||||
|
||||
const len_ETHER = 14
|
||||
|
||||
type ICMPv6 struct {
|
||||
tun *TunAdapter
|
||||
mylladdr net.IP
|
||||
mymac macAddress
|
||||
peermacs map[address.Address]neighbor
|
||||
}
|
||||
|
||||
type neighbor struct {
|
||||
mac macAddress
|
||||
learned bool
|
||||
lastadvertisement time.Time
|
||||
lastsolicitation time.Time
|
||||
}
|
||||
|
||||
// Marshal returns the binary encoding of h.
|
||||
func ipv6Header_Marshal(h *ipv6.Header) ([]byte, error) {
|
||||
b := make([]byte, 40)
|
||||
b[0] |= byte(h.Version) << 4
|
||||
b[0] |= byte(h.TrafficClass) >> 4
|
||||
b[1] |= byte(h.TrafficClass) << 4
|
||||
b[1] |= byte(h.FlowLabel >> 16)
|
||||
b[2] = byte(h.FlowLabel >> 8)
|
||||
b[3] = byte(h.FlowLabel)
|
||||
binary.BigEndian.PutUint16(b[4:6], uint16(h.PayloadLen))
|
||||
b[6] = byte(h.NextHeader)
|
||||
b[7] = byte(h.HopLimit)
|
||||
copy(b[8:24], h.Src)
|
||||
copy(b[24:40], h.Dst)
|
||||
return b, nil
|
||||
}
|
||||
|
||||
// Initialises the ICMPv6 module by assigning our link-local IPv6 address and
|
||||
// our MAC address. ICMPv6 messages will always appear to originate from these
|
||||
// addresses.
|
||||
func (i *ICMPv6) Init(t *TunAdapter) {
|
||||
i.tun = t
|
||||
i.peermacs = make(map[address.Address]neighbor)
|
||||
|
||||
// Our MAC address and link-local address
|
||||
i.mymac = macAddress{
|
||||
0x02, 0x00, 0x00, 0x00, 0x00, 0x02}
|
||||
i.mylladdr = net.IP{
|
||||
0xFE, 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
|
||||
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x80, 0xFE}
|
||||
copy(i.mymac[:], i.tun.addr[:])
|
||||
copy(i.mylladdr[9:], i.tun.addr[1:])
|
||||
}
|
||||
|
||||
// Parses an incoming ICMPv6 packet. The packet provided may be either an
|
||||
// ethernet frame containing an IP packet, or the IP packet alone. This is
|
||||
// determined by whether the TUN/TAP adapter is running in TUN (layer 3) or
|
||||
// TAP (layer 2) mode.
|
||||
func (i *ICMPv6) ParsePacket(datain []byte) {
|
||||
var response []byte
|
||||
var err error
|
||||
|
||||
// Parse the frame/packet
|
||||
if i.tun.IsTAP() {
|
||||
response, err = i.UnmarshalPacketL2(datain)
|
||||
} else {
|
||||
response, err = i.UnmarshalPacket(datain, nil)
|
||||
}
|
||||
|
||||
if err != nil {
|
||||
return
|
||||
}
|
||||
|
||||
// Write the packet to TUN/TAP
|
||||
i.tun.Send <- response
|
||||
}
|
||||
|
||||
// Unwraps the ethernet headers of an incoming ICMPv6 packet and hands off
|
||||
// the IP packet to the ParsePacket function for further processing.
|
||||
// A response buffer is also created for the response message, also complete
|
||||
// with ethernet headers.
|
||||
func (i *ICMPv6) UnmarshalPacketL2(datain []byte) ([]byte, error) {
|
||||
// Ignore non-IPv6 frames
|
||||
if binary.BigEndian.Uint16(datain[12:14]) != uint16(0x86DD) {
|
||||
return nil, nil
|
||||
}
|
||||
|
||||
// Hand over to ParsePacket to interpret the IPv6 packet
|
||||
mac := datain[6:12]
|
||||
ipv6packet, err := i.UnmarshalPacket(datain[len_ETHER:], &mac)
|
||||
if err != nil {
|
||||
return nil, err
|
||||
}
|
||||
|
||||
// Create the response buffer
|
||||
dataout := make([]byte, len_ETHER+ipv6.HeaderLen+32)
|
||||
|
||||
// Populate the response ethernet headers
|
||||
copy(dataout[:6], datain[6:12])
|
||||
copy(dataout[6:12], i.mymac[:])
|
||||
binary.BigEndian.PutUint16(dataout[12:14], uint16(0x86DD))
|
||||
|
||||
// Copy the returned packet to our response ethernet frame
|
||||
copy(dataout[len_ETHER:], ipv6packet)
|
||||
return dataout, nil
|
||||
}
|
||||
|
||||
// Unwraps the IP headers of an incoming IPv6 packet and performs various
|
||||
// sanity checks on the packet - i.e. is the packet an ICMPv6 packet, does the
|
||||
// ICMPv6 message match a known expected type. The relevant handler function
|
||||
// is then called and a response packet may be returned.
|
||||
func (i *ICMPv6) UnmarshalPacket(datain []byte, datamac *[]byte) ([]byte, error) {
|
||||
// Parse the IPv6 packet headers
|
||||
ipv6Header, err := ipv6.ParseHeader(datain[:ipv6.HeaderLen])
|
||||
if err != nil {
|
||||
return nil, err
|
||||
}
|
||||
|
||||
// Check if the packet is IPv6
|
||||
if ipv6Header.Version != ipv6.Version {
|
||||
return nil, err
|
||||
}
|
||||
|
||||
// Check if the packet is ICMPv6
|
||||
if ipv6Header.NextHeader != 58 {
|
||||
return nil, err
|
||||
}
|
||||
|
||||
// Parse the ICMPv6 message contents
|
||||
icmpv6Header, err := icmp.ParseMessage(58, datain[ipv6.HeaderLen:])
|
||||
if err != nil {
|
||||
return nil, err
|
||||
}
|
||||
|
||||
// Check for a supported message type
|
||||
switch icmpv6Header.Type {
|
||||
case ipv6.ICMPTypeNeighborSolicitation:
|
||||
if !i.tun.IsTAP() {
|
||||
return nil, errors.New("Ignoring Neighbor Solicitation in TUN mode")
|
||||
}
|
||||
response, err := i.HandleNDP(datain[ipv6.HeaderLen:])
|
||||
if err == nil {
|
||||
// Create our ICMPv6 response
|
||||
responsePacket, err := CreateICMPv6(
|
||||
ipv6Header.Src, i.mylladdr,
|
||||
ipv6.ICMPTypeNeighborAdvertisement, 0,
|
||||
&icmp.DefaultMessageBody{Data: response})
|
||||
if err != nil {
|
||||
return nil, err
|
||||
}
|
||||
|
||||
// Send it back
|
||||
return responsePacket, nil
|
||||
} else {
|
||||
return nil, err
|
||||
}
|
||||
case ipv6.ICMPTypeNeighborAdvertisement:
|
||||
if !i.tun.IsTAP() {
|
||||
return nil, errors.New("Ignoring Neighbor Advertisement in TUN mode")
|
||||
}
|
||||
if datamac != nil {
|
||||
var addr address.Address
|
||||
var target address.Address
|
||||
var mac macAddress
|
||||
copy(addr[:], ipv6Header.Src[:])
|
||||
copy(target[:], datain[48:64])
|
||||
copy(mac[:], (*datamac)[:])
|
||||
// i.tun.core.log.Printf("Learning peer MAC %x for %x\n", mac, target)
|
||||
neighbor := i.peermacs[target]
|
||||
neighbor.mac = mac
|
||||
neighbor.learned = true
|
||||
neighbor.lastadvertisement = time.Now()
|
||||
i.peermacs[target] = neighbor
|
||||
}
|
||||
return nil, errors.New("No response needed")
|
||||
}
|
||||
|
||||
return nil, errors.New("ICMPv6 type not matched")
|
||||
}
|
||||
|
||||
// Creates an ICMPv6 packet based on the given icmp.MessageBody and other
|
||||
// parameters, complete with ethernet and IP headers, which can be written
|
||||
// directly to a TAP adapter.
|
||||
func (i *ICMPv6) CreateICMPv6L2(dstmac macAddress, dst net.IP, src net.IP, mtype ipv6.ICMPType, mcode int, mbody icmp.MessageBody) ([]byte, error) {
|
||||
// Pass through to CreateICMPv6
|
||||
ipv6packet, err := CreateICMPv6(dst, src, mtype, mcode, mbody)
|
||||
if err != nil {
|
||||
return nil, err
|
||||
}
|
||||
|
||||
// Create the response buffer
|
||||
dataout := make([]byte, len_ETHER+len(ipv6packet))
|
||||
|
||||
// Populate the response ethernet headers
|
||||
copy(dataout[:6], dstmac[:6])
|
||||
copy(dataout[6:12], i.mymac[:])
|
||||
binary.BigEndian.PutUint16(dataout[12:14], uint16(0x86DD))
|
||||
|
||||
// Copy the returned packet to our response ethernet frame
|
||||
copy(dataout[len_ETHER:], ipv6packet)
|
||||
return dataout, nil
|
||||
}
|
||||
|
||||
// Creates an ICMPv6 packet based on the given icmp.MessageBody and other
|
||||
// parameters, complete with IP headers only, which can be written directly to
|
||||
// a TUN adapter, or called directly by the CreateICMPv6L2 function when
|
||||
// generating a message for TAP adapters.
|
||||
func CreateICMPv6(dst net.IP, src net.IP, mtype ipv6.ICMPType, mcode int, mbody icmp.MessageBody) ([]byte, error) {
|
||||
// Create the ICMPv6 message
|
||||
icmpMessage := icmp.Message{
|
||||
Type: mtype,
|
||||
Code: mcode,
|
||||
Body: mbody,
|
||||
}
|
||||
|
||||
// Convert the ICMPv6 message into []byte
|
||||
icmpMessageBuf, err := icmpMessage.Marshal(icmp.IPv6PseudoHeader(src, dst))
|
||||
if err != nil {
|
||||
return nil, err
|
||||
}
|
||||
|
||||
// Create the IPv6 header
|
||||
ipv6Header := ipv6.Header{
|
||||
Version: ipv6.Version,
|
||||
NextHeader: 58,
|
||||
PayloadLen: len(icmpMessageBuf),
|
||||
HopLimit: 255,
|
||||
Src: src,
|
||||
Dst: dst,
|
||||
}
|
||||
|
||||
// Convert the IPv6 header into []byte
|
||||
ipv6HeaderBuf, err := ipv6Header_Marshal(&ipv6Header)
|
||||
if err != nil {
|
||||
return nil, err
|
||||
}
|
||||
|
||||
// Construct the packet
|
||||
responsePacket := make([]byte, ipv6.HeaderLen+ipv6Header.PayloadLen)
|
||||
copy(responsePacket[:ipv6.HeaderLen], ipv6HeaderBuf)
|
||||
copy(responsePacket[ipv6.HeaderLen:], icmpMessageBuf)
|
||||
|
||||
// Send it back
|
||||
return responsePacket, nil
|
||||
}
|
||||
|
||||
func (i *ICMPv6) CreateNDPL2(dst address.Address) ([]byte, error) {
|
||||
// Create the ND payload
|
||||
var payload [28]byte
|
||||
copy(payload[:4], []byte{0x00, 0x00, 0x00, 0x00})
|
||||
copy(payload[4:20], dst[:])
|
||||
copy(payload[20:22], []byte{0x01, 0x01})
|
||||
copy(payload[22:28], i.mymac[:6])
|
||||
|
||||
// Create the ICMPv6 solicited-node address
|
||||
var dstaddr address.Address
|
||||
copy(dstaddr[:13], []byte{
|
||||
0xFF, 0x02, 0x00, 0x00,
|
||||
0x00, 0x00, 0x00, 0x00,
|
||||
0x00, 0x00, 0x00, 0x01, 0xFF})
|
||||
copy(dstaddr[13:], dst[13:16])
|
||||
|
||||
// Create the multicast MAC
|
||||
var dstmac macAddress
|
||||
copy(dstmac[:2], []byte{0x33, 0x33})
|
||||
copy(dstmac[2:6], dstaddr[12:16])
|
||||
|
||||
// Create the ND request
|
||||
requestPacket, err := i.CreateICMPv6L2(
|
||||
dstmac, dstaddr[:], i.mylladdr,
|
||||
ipv6.ICMPTypeNeighborSolicitation, 0,
|
||||
&icmp.DefaultMessageBody{Data: payload[:]})
|
||||
if err != nil {
|
||||
return nil, err
|
||||
}
|
||||
neighbor := i.peermacs[dstaddr]
|
||||
neighbor.lastsolicitation = time.Now()
|
||||
i.peermacs[dstaddr] = neighbor
|
||||
|
||||
return requestPacket, nil
|
||||
}
|
||||
|
||||
// Generates a response to an NDP discovery packet. This is effectively called
|
||||
// when the host operating system generates an NDP request for any address in
|
||||
// the fd00::/8 range, so that the operating system knows to route that traffic
|
||||
// to the Yggdrasil TAP adapter.
|
||||
func (i *ICMPv6) HandleNDP(in []byte) ([]byte, error) {
|
||||
// Ignore NDP requests for anything outside of fd00::/8
|
||||
var source address.Address
|
||||
copy(source[:], in[8:])
|
||||
var snet address.Subnet
|
||||
copy(snet[:], in[8:])
|
||||
switch {
|
||||
case source.IsValid():
|
||||
case snet.IsValid():
|
||||
default:
|
||||
return nil, errors.New("Not an NDP for 0200::/7")
|
||||
}
|
||||
|
||||
// Create our NDP message body response
|
||||
body := make([]byte, 28)
|
||||
binary.BigEndian.PutUint32(body[:4], uint32(0x20000000))
|
||||
copy(body[4:20], in[8:24]) // Target address
|
||||
body[20] = uint8(2)
|
||||
body[21] = uint8(1)
|
||||
copy(body[22:28], i.mymac[:6])
|
||||
|
||||
// Send it back
|
||||
return body, nil
|
||||
}
|
||||
Loading…
Add table
Add a link
Reference in a new issue