yggdrasil-network/yggdrasil-go
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move ICMP PacketTooBig sending into core

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This commit is contained in:
Arceliar 2021-06-13 05:25:13 -05:00
parent 8621223a1f
commit 3393db8e77
5 changed files with 33 additions and 106 deletions
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12
src/core/api.go
View file

@ -231,6 +231,18 @@ func (c *Core) MaxMTU() uint64 {
return c.store.maxSessionMTU()
}
// SetMTU can only safely be called after Init and before Start.
func (c *Core) SetMTU(mtu uint64) {
if mtu < 1280 {
mtu = 1280
}
c.store.mtu = mtu
}
func (c *Core) MTU() uint64 {
return c.store.mtu
}
// Implement io.ReadWriteCloser
func (c *Core) Read(p []byte) (n int, err error) {

30
src/core/keystore.go
View file

@ -7,6 +7,9 @@ import (
"sync"
"time"
"golang.org/x/net/icmp"
"golang.org/x/net/ipv6"
iwt "github.com/Arceliar/ironwood/types"
"github.com/yggdrasil-network/yggdrasil-go/src/address"
@ -26,6 +29,7 @@ type keyStore struct {
addrBuffer map[address.Address]*buffer
subnetToInfo map[address.Subnet]*keyInfo
subnetBuffer map[address.Subnet]*buffer
mtu uint64
}
type keyInfo struct {
@ -53,6 +57,7 @@ func (k *keyStore) init(core *Core) {
k.addrBuffer = make(map[address.Address]*buffer)
k.subnetToInfo = make(map[address.Subnet]*keyInfo)
k.subnetBuffer = make(map[address.Subnet]*buffer)
k.mtu = 1280 // Default to something safe, expect user to set this
}
func (k *keyStore) sendToAddress(addr address.Address, bs []byte) {
@ -238,18 +243,19 @@ func (k *keyStore) readPC(p []byte) (int, error) {
if len(bs) < 40 {
continue
}
/* TODO? ICMP packet too big, for now tuntap sends this when needed
if len(bs) > int(tun.MTU()) {
ptb := &icmp.PacketTooBig{
MTU: int(tun.mtu),
Data: bs[:40],
}
if packet, err := CreateICMPv6(bs[8:24], bs[24:40], ipv6.ICMPTypePacketTooBig, 0, ptb); err == nil {
_, _ = tun.core.WriteTo(packet, from)
}
continue
}
*/
if len(bs) > int(k.mtu) {
// Using bs would make it leak off the stack, so copy to buf
buf := make([]byte, 40)
copy(buf, bs)
ptb := &icmp.PacketTooBig{
MTU: int(k.mtu),
Data: buf[:40],
}
if packet, err := CreateICMPv6(buf[8:24], buf[24:40], ipv6.ICMPTypePacketTooBig, 0, ptb); err == nil {
_, _ = k.writePC(packet)
}
continue
}
var srcAddr, dstAddr address.Address
var srcSubnet, dstSubnet address.Subnet
copy(srcAddr[:], bs[8:])

80
src/tuntap/icmpv6.go
View file

@ -1,80 +0,0 @@
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"
"net"
"golang.org/x/net/icmp"
"golang.org/x/net/ipv6"
)
type ICMPv6 struct{}
// 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
}
// 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
}

16
src/tuntap/iface.go
View file

@ -1,10 +1,5 @@
package tuntap
import (
"golang.org/x/net/icmp"
"golang.org/x/net/ipv6"
)
const TUN_OFFSET_BYTES = 4
func (tun *TunAdapter) read() {
@ -37,15 +32,8 @@ func (tun *TunAdapter) write() {
tun.log.Errorln("Exiting tun writer due to core read error:", err)
return
}
if n > int(tun.MTU()) {
ptb := &icmp.PacketTooBig{
MTU: int(tun.mtu),
Data: bs[:40],
}
if packet, err := CreateICMPv6(bs[8:24], bs[24:40], ipv6.ICMPTypePacketTooBig, 0, ptb); err == nil {
_, _ = tun.core.Write(packet)
}
continue
if !tun.isEnabled {
continue // Nothing to do, the tun isn't enabled
}
bs = buf[:TUN_OFFSET_BYTES+n]
if _, err = tun.iface.Write(bs, TUN_OFFSET_BYTES); err != nil {

1
src/tuntap/tun.go
View file

@ -139,6 +139,7 @@ func (tun *TunAdapter) _start() error {
if tun.MTU() != mtu {
tun.log.Warnf("Warning: Interface MTU %d automatically adjusted to %d (supported range is 1280-%d)", tun.config.IfMTU, tun.MTU(), MaximumMTU())
}
tun.core.SetMTU(tun.MTU())
tun.isOpen = true
tun.isEnabled = true
go tun.read()