yggdrasil-go/src/tuntap/iface.go

286 lines
8.2 KiB
Go
Raw Normal View History

package tuntap
import (
"bytes"
"errors"
"time"
"github.com/songgao/packets/ethernet"
"github.com/yggdrasil-network/yggdrasil-go/src/address"
"github.com/yggdrasil-network/yggdrasil-go/src/crypto"
"github.com/yggdrasil-network/yggdrasil-go/src/util"
)
func (tun *TunAdapter) writer() error {
var w int
var err error
for {
b := <-tun.send
n := len(b)
if n == 0 {
continue
}
if tun.iface.IsTAP() {
var dstAddr address.Address
if b[0]&0xf0 == 0x60 {
if len(b) < 40 {
//panic("Tried to send a packet shorter than an IPv6 header...")
util.PutBytes(b)
continue
}
copy(dstAddr[:16], b[24:])
} else if b[0]&0xf0 == 0x40 {
if len(b) < 20 {
//panic("Tried to send a packet shorter than an IPv4 header...")
util.PutBytes(b)
continue
}
copy(dstAddr[:4], b[16:])
} else {
return errors.New("Invalid address family")
}
sendndp := func(dstAddr address.Address) {
neigh, known := tun.icmpv6.peermacs[dstAddr]
known = known && (time.Since(neigh.lastsolicitation).Seconds() < 30)
if !known {
request, err := tun.icmpv6.CreateNDPL2(dstAddr)
if err != nil {
panic(err)
}
if _, err := tun.iface.Write(request); err != nil {
panic(err)
}
tun.icmpv6.peermacs[dstAddr] = neighbor{
lastsolicitation: time.Now(),
}
}
}
var peermac macAddress
var peerknown bool
if b[0]&0xf0 == 0x40 {
dstAddr = tun.addr
} else if b[0]&0xf0 == 0x60 {
if !bytes.Equal(tun.addr[:16], dstAddr[:16]) && !bytes.Equal(tun.subnet[:8], dstAddr[:8]) {
dstAddr = tun.addr
}
}
if neighbor, ok := tun.icmpv6.peermacs[dstAddr]; ok && neighbor.learned {
peermac = neighbor.mac
peerknown = true
} else if neighbor, ok := tun.icmpv6.peermacs[tun.addr]; ok && neighbor.learned {
peermac = neighbor.mac
peerknown = true
sendndp(dstAddr)
} else {
sendndp(tun.addr)
}
if peerknown {
var proto ethernet.Ethertype
switch {
case b[0]&0xf0 == 0x60:
proto = ethernet.IPv6
case b[0]&0xf0 == 0x40:
proto = ethernet.IPv4
}
var frame ethernet.Frame
frame.Prepare(
peermac[:6], // Destination MAC address
tun.icmpv6.mymac[:6], // Source MAC address
ethernet.NotTagged, // VLAN tagging
proto, // Ethertype
len(b)) // Payload length
copy(frame[tun_ETHER_HEADER_LENGTH:], b[:n])
n += tun_ETHER_HEADER_LENGTH
w, err = tun.iface.Write(frame[:n])
}
} else {
w, err = tun.iface.Write(b[:n])
util.PutBytes(b)
}
if err != nil {
if !tun.isOpen {
return err
}
tun.log.Errorln("TUN/TAP iface write error:", err)
continue
}
if w != n {
tun.log.Errorln("TUN/TAP iface write mismatch:", w, "bytes written vs", n, "bytes given")
continue
}
}
}
func (tun *TunAdapter) reader() error {
bs := make([]byte, 65535)
for {
// Wait for a packet to be delivered to us through the TUN/TAP adapter
n, err := tun.iface.Read(bs)
if err != nil {
if !tun.isOpen {
return err
}
panic(err)
}
if n == 0 {
continue
}
// If it's a TAP adapter, update the buffer slice so that we no longer
// include the ethernet headers
offset := 0
if tun.iface.IsTAP() {
// Set our offset to beyond the ethernet headers
offset = tun_ETHER_HEADER_LENGTH
// If we detect an ICMP packet then hand it to the ICMPv6 module
if bs[offset+6] == 58 {
// Found an ICMPv6 packet
b := make([]byte, n)
copy(b, bs)
go tun.icmpv6.ParsePacket(b)
}
// Then offset the buffer so that we can now just treat it as an IP
// packet from now on
bs = bs[offset:] // FIXME this breaks bs for the next read and means n is the wrong value
}
// From the IP header, work out what our source and destination addresses
// and node IDs are. We will need these in order to work out where to send
// the packet
var srcAddr address.Address
var dstAddr address.Address
var dstNodeID *crypto.NodeID
var dstNodeIDMask *crypto.NodeID
var dstSnet address.Subnet
var addrlen int
// Check the IP protocol - if it doesn't match then we drop the packet and
// do nothing with it
if bs[0]&0xf0 == 0x60 {
// Check if we have a fully-sized IPv6 header
if len(bs) < 40 {
continue
}
// Check the packet size
if n != 256*int(bs[4])+int(bs[5])+offset+tun_IPv6_HEADER_LENGTH {
continue
}
// IPv6 address
addrlen = 16
copy(srcAddr[:addrlen], bs[8:])
copy(dstAddr[:addrlen], bs[24:])
copy(dstSnet[:addrlen/2], bs[24:])
} else if bs[0]&0xf0 == 0x40 {
// Check if we have a fully-sized IPv4 header
if len(bs) < 20 {
continue
}
// Check the packet size
if n != 256*int(bs[2])+int(bs[3])+offset {
continue
}
// IPv4 address
addrlen = 4
copy(srcAddr[:addrlen], bs[12:])
copy(dstAddr[:addrlen], bs[16:])
} else {
// Unknown address length or protocol, so drop the packet and ignore it
continue
}
2019-05-18 00:09:20 +03:00
if !tun.ckr.isValidSource(srcAddr, addrlen) {
// The packet had a source address that doesn't belong to us or our
// configured crypto-key routing source subnets
continue
}
2019-05-18 00:09:20 +03:00
if !dstAddr.IsValid() && !dstSnet.IsValid() {
if key, err := tun.ckr.getPublicKeyForAddress(dstAddr, addrlen); err == nil {
// A public key was found, get the node ID for the search
dstNodeID = crypto.GetNodeID(&key)
// Do a quick check to ensure that the node ID refers to a vaild
// Yggdrasil address or subnet - this might be superfluous
addr := *address.AddrForNodeID(dstNodeID)
copy(dstAddr[:], addr[:])
copy(dstSnet[:], addr[:])
// Are we certain we looked up a valid node?
if !dstAddr.IsValid() && !dstSnet.IsValid() {
continue
}
} else {
// No public key was found in the CKR table so we've exhausted our options
continue
}
}
// Do we have an active connection for this node address?
tun.mutex.RLock()
session, isIn := tun.addrToConn[dstAddr]
if !isIn || session == nil {
session, isIn = tun.subnetToConn[dstSnet]
if !isIn || session == nil {
// Neither an address nor a subnet mapping matched, therefore populate
// the node ID and mask to commence a search
if dstAddr.IsValid() {
dstNodeID, dstNodeIDMask = dstAddr.GetNodeIDandMask()
} else {
dstNodeID, dstNodeIDMask = dstSnet.GetNodeIDandMask()
}
}
}
tun.mutex.RUnlock()
// If we don't have a connection then we should open one
if !isIn || session == nil {
// Check we haven't been given empty node ID, really this shouldn't ever
// happen but just to be sure...
if dstNodeID == nil || dstNodeIDMask == nil {
panic("Given empty dstNodeID and dstNodeIDMask - this shouldn't happen")
}
// Dial to the remote node
2019-06-30 02:44:24 +03:00
packet := append(util.GetBytes(), bs[:n]...)
go func() {
// FIXME just spitting out a goroutine to do this is kind of ugly and means we drop packets until the dial finishes
tun.mutex.Lock()
_, known := tun.dials[*dstNodeID]
tun.dials[*dstNodeID] = append(tun.dials[*dstNodeID], packet)
for len(tun.dials[*dstNodeID]) > 32 {
util.PutBytes(tun.dials[*dstNodeID][0])
tun.dials[*dstNodeID] = tun.dials[*dstNodeID][1:]
}
tun.mutex.Unlock()
if known {
return
}
var tc *tunConn
if conn, err := tun.dialer.DialByNodeIDandMask(dstNodeID, dstNodeIDMask); err == nil {
// We've been given a connection so prepare the session wrapper
if tc, err = tun.wrap(conn); err != nil {
// Something went wrong when storing the connection, typically that
// something already exists for this address or subnet
tun.log.Debugln("TUN/TAP iface wrap:", err)
}
}
tun.mutex.Lock()
packets := tun.dials[*dstNodeID]
delete(tun.dials, *dstNodeID)
tun.mutex.Unlock()
if tc != nil {
for _, packet := range packets {
select {
case tc.send <- packet:
default:
util.PutBytes(packet)
}
}
}
}()
// While the dial is going on we can't do much else
// continuing this iteration - skip to the next one
continue
}
// If we have a connection now, try writing to it
if isIn && session != nil {
packet := append(util.GetBytes(), bs[:n]...)
select {
case session.send <- packet:
default:
util.PutBytes(packet)
}
}
}
}