mirror of
https://github.com/yggdrasil-network/yggdrasil-go.git
synced 2025-03-09 15:40:15 +00:00
277 lines
8.1 KiB
Go
277 lines
8.1 KiB
Go
package tuntap
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import (
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"bytes"
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"net"
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"time"
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"github.com/songgao/packets/ethernet"
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"github.com/yggdrasil-network/yggdrasil-go/src/address"
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"github.com/yggdrasil-network/yggdrasil-go/src/crypto"
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"github.com/yggdrasil-network/yggdrasil-go/src/util"
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"github.com/Arceliar/phony"
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)
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type tunWriter struct {
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phony.Inbox
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tun *TunAdapter
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}
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func (w *tunWriter) writeFrom(from phony.Actor, b []byte) {
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w.RecvFrom(from, func() {
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w._write(b)
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})
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}
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// write is pretty loose with the memory safety rules, e.g. it assumes it can read w.tun.iface.IsTap() safely
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func (w *tunWriter) _write(b []byte) {
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var written int
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var err error
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n := len(b)
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if n == 0 {
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return
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}
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if w.tun.iface.IsTAP() {
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sendndp := func(dstAddr address.Address) {
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neigh, known := w.tun.icmpv6.getNeighbor(dstAddr)
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known = known && (time.Since(neigh.lastsolicitation).Seconds() < 30)
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if !known {
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w.tun.icmpv6.Solicit(dstAddr)
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}
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}
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peermac := net.HardwareAddr{0x00, 0x00, 0x00, 0x00, 0x00, 0x00}
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var dstAddr address.Address
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var peerknown bool
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if b[0]&0xf0 == 0x40 {
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dstAddr = w.tun.addr
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} else if b[0]&0xf0 == 0x60 {
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if !bytes.Equal(w.tun.addr[:16], dstAddr[:16]) && !bytes.Equal(w.tun.subnet[:8], dstAddr[:8]) {
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dstAddr = w.tun.addr
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}
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}
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if neighbor, ok := w.tun.icmpv6.getNeighbor(dstAddr); ok && neighbor.learned {
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// If we've learned the MAC of a 300::/7 address, for example, or a CKR
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// address, use the MAC address of that
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peermac = neighbor.mac
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peerknown = true
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} else if neighbor, ok := w.tun.icmpv6.getNeighbor(w.tun.addr); ok && neighbor.learned {
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// Otherwise send directly to the MAC address of the host if that's
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// known instead
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peermac = neighbor.mac
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peerknown = true
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} else {
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// Nothing has been discovered, try to discover the destination
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sendndp(w.tun.addr)
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}
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if peerknown {
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var proto ethernet.Ethertype
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switch {
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case b[0]&0xf0 == 0x60:
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proto = ethernet.IPv6
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case b[0]&0xf0 == 0x40:
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proto = ethernet.IPv4
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}
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var frame ethernet.Frame
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frame.Prepare(
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peermac[:6], // Destination MAC address
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w.tun.icmpv6.mymac[:6], // Source MAC address
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ethernet.NotTagged, // VLAN tagging
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proto, // Ethertype
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len(b)) // Payload length
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copy(frame[tun_ETHER_HEADER_LENGTH:], b[:n])
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n += tun_ETHER_HEADER_LENGTH
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written, err = w.tun.iface.Write(frame[:n])
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} else {
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w.tun.log.Errorln("TUN/TAP iface write error: no peer MAC known for", net.IP(dstAddr[:]).String(), "- dropping packet")
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}
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} else {
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written, err = w.tun.iface.Write(b[:n])
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util.PutBytes(b)
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}
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if err != nil {
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w.tun.RecvFrom(w, func() {
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if !w.tun.isOpen {
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w.tun.log.Errorln("TUN/TAP iface write error:", err)
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}
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})
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}
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if written != n {
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w.tun.log.Errorln("TUN/TAP iface write mismatch:", written, "bytes written vs", n, "bytes given")
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}
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}
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type tunReader struct {
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phony.Inbox
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tun *TunAdapter
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}
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func (r *tunReader) _read() {
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// Get a slice to store the packet in
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recvd := util.ResizeBytes(util.GetBytes(), 65535+tun_ETHER_HEADER_LENGTH)
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// Wait for a packet to be delivered to us through the TUN/TAP adapter
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n, err := r.tun.iface.Read(recvd)
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if n == 0 {
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util.PutBytes(recvd)
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} else {
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r.tun.handlePacketFrom(r, recvd[:n], err)
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}
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if err == nil {
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// Now read again
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r.RecvFrom(nil, r._read)
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}
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}
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func (tun *TunAdapter) handlePacketFrom(from phony.Actor, packet []byte, err error) {
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tun.RecvFrom(from, func() {
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tun._handlePacket(packet, err)
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})
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}
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// does the work of reading a packet and sending it to the correct tunConn
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func (tun *TunAdapter) _handlePacket(recvd []byte, err error) {
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if err != nil {
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tun.log.Errorln("TUN/TAP iface read error:", err)
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return
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}
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// If it's a TAP adapter, update the buffer slice so that we no longer
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// include the ethernet headers
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offset := 0
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if tun.iface.IsTAP() {
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// Set our offset to beyond the ethernet headers
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offset = tun_ETHER_HEADER_LENGTH
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// Check first of all that we can go beyond the ethernet headers
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if len(recvd) <= offset {
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return
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}
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}
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// Offset the buffer from now on so that we can ignore ethernet frames if
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// they are present
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bs := recvd[offset:]
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// If we detect an ICMP packet then hand it to the ICMPv6 module
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if bs[6] == 58 {
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// Found an ICMPv6 packet - we need to make sure to give ICMPv6 the full
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// Ethernet frame rather than just the IPv6 packet as this is needed for
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// NDP to work correctly
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if err := tun.icmpv6.ParsePacket(recvd); err == nil {
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// We acted on the packet in the ICMPv6 module so don't forward or do
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// anything else with it
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return
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}
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}
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if offset != 0 {
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// Shift forward to avoid leaking bytes off the front of the slice when we eventually store it
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bs = append(recvd[:0], bs...)
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}
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// From the IP header, work out what our source and destination addresses
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// and node IDs are. We will need these in order to work out where to send
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// the packet
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var dstAddr address.Address
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var dstSnet address.Subnet
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var addrlen int
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n := len(bs)
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// Check the IP protocol - if it doesn't match then we drop the packet and
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// do nothing with it
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if bs[0]&0xf0 == 0x60 {
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// Check if we have a fully-sized IPv6 header
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if len(bs) < 40 {
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return
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}
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// Check the packet size
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if n-tun_IPv6_HEADER_LENGTH != 256*int(bs[4])+int(bs[5]) {
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return
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}
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// IPv6 address
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addrlen = 16
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copy(dstAddr[:addrlen], bs[24:])
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copy(dstSnet[:addrlen/2], bs[24:])
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} else if bs[0]&0xf0 == 0x40 {
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// Check if we have a fully-sized IPv4 header
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if len(bs) < 20 {
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return
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}
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// Check the packet size
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if n != 256*int(bs[2])+int(bs[3]) {
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return
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}
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// IPv4 address
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addrlen = 4
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copy(dstAddr[:addrlen], bs[16:])
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} else {
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// Unknown address length or protocol, so drop the packet and ignore it
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tun.log.Traceln("Unknown packet type, dropping")
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return
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}
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if tun.ckr.isEnabled() {
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if addrlen != 16 || (!dstAddr.IsValid() && !dstSnet.IsValid()) {
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if key, err := tun.ckr.getPublicKeyForAddress(dstAddr, addrlen); err == nil {
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// A public key was found, get the node ID for the search
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dstNodeID := crypto.GetNodeID(&key)
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dstAddr = *address.AddrForNodeID(dstNodeID)
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dstSnet = *address.SubnetForNodeID(dstNodeID)
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addrlen = 16
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}
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}
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}
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if addrlen != 16 || (!dstAddr.IsValid() && !dstSnet.IsValid()) {
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// Couldn't find this node's ygg IP
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return
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}
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// Do we have an active connection for this node address?
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var dstNodeID, dstNodeIDMask *crypto.NodeID
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session, isIn := tun.addrToConn[dstAddr]
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if !isIn || session == nil {
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session, isIn = tun.subnetToConn[dstSnet]
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if !isIn || session == nil {
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// Neither an address nor a subnet mapping matched, therefore populate
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// the node ID and mask to commence a search
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if dstAddr.IsValid() {
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dstNodeID, dstNodeIDMask = dstAddr.GetNodeIDandMask()
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} else {
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dstNodeID, dstNodeIDMask = dstSnet.GetNodeIDandMask()
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}
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}
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}
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// If we don't have a connection then we should open one
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if !isIn || session == nil {
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// Check we haven't been given empty node ID, really this shouldn't ever
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// happen but just to be sure...
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if dstNodeID == nil || dstNodeIDMask == nil {
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panic("Given empty dstNodeID and dstNodeIDMask - this shouldn't happen")
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}
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_, known := tun.dials[*dstNodeID]
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tun.dials[*dstNodeID] = append(tun.dials[*dstNodeID], bs)
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for len(tun.dials[*dstNodeID]) > 32 {
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util.PutBytes(tun.dials[*dstNodeID][0])
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tun.dials[*dstNodeID] = tun.dials[*dstNodeID][1:]
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}
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if !known {
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go func() {
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conn, err := tun.dialer.DialByNodeIDandMask(dstNodeID, dstNodeIDMask)
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tun.RecvFrom(nil, func() {
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packets := tun.dials[*dstNodeID]
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delete(tun.dials, *dstNodeID)
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if err != nil {
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return
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}
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// We've been given a connection so prepare the session wrapper
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var tc *tunConn
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if tc, err = tun._wrap(conn); err != nil {
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// Something went wrong when storing the connection, typically that
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// something already exists for this address or subnet
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tun.log.Debugln("TUN/TAP iface wrap:", err)
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return
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}
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for _, packet := range packets {
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tc.writeFrom(nil, packet)
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}
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})
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return
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}()
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}
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}
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// If we have a connection now, try writing to it
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if isIn && session != nil {
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session.writeFrom(tun, bs)
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}
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}
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