yggdrasil-network/yggdrasil-go
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Document ICMPv6 and TUN/TAP

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This commit is contained in:
Neil Alexander 2018-06-12 22:45:53 +01:00
parent ad6ea59049
commit 8e2c2aa977
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10 changed files with 90 additions and 4 deletions
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19
src/yggdrasil/tun.go
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@ -8,6 +8,7 @@ import "github.com/yggdrasil-network/water"
const tun_IPv6_HEADER_LENGTH = 40
const tun_ETHER_HEADER_LENGTH = 14
// Represents a running TUN/TAP interface.
type tunDevice struct {
core *Core
icmpv6 icmpv6
@ -17,6 +18,9 @@ type tunDevice struct {
iface *water.Interface
}
// Defines which parameters are expected by default for a TUN/TAP adapter on a
// specific platform. These values are populated in the relevant tun_*.go for
// the platform being targeted. They must be set.
type tunDefaultParameters struct {
maximumIfMTU int
defaultIfMTU int
@ -24,6 +28,8 @@ type tunDefaultParameters struct {
defaultIfTAPMode bool
}
// Gets the maximum supported MTU for the platform based on the defaults in
// getDefaults().
func getSupportedMTU(mtu int) int {
if mtu > getDefaults().maximumIfMTU {
return getDefaults().maximumIfMTU
@ -31,11 +37,14 @@ func getSupportedMTU(mtu int) int {
return mtu
}
// Initialises the TUN/TAP adapter.
func (tun *tunDevice) init(core *Core) {
tun.core = core
tun.icmpv6.init(tun)
}
// Starts the setup process for the TUN/TAP adapter, and if successful, starts
// the read/write goroutines to handle packets on that interface.
func (tun *tunDevice) start(ifname string, iftapmode bool, addr string, mtu int) error {
if ifname == "none" {
return nil
@ -48,6 +57,9 @@ func (tun *tunDevice) start(ifname string, iftapmode bool, addr string, mtu int)
return nil
}
// Writes a packet to the TUN/TAP adapter. If the adapter is running in TAP
// mode then additional ethernet encapsulation is added for the benefit of the
// host operating system.
func (tun *tunDevice) write() error {
for {
data := <-tun.recv
@ -75,6 +87,10 @@ func (tun *tunDevice) write() error {
}
}
// Reads any packets that are waiting on the TUN/TAP adapter. If the adapter
// is running in TAP mode then the ethernet headers will automatically be
// processed and stripped if necessary. If an ICMPv6 packet is found, then
// the relevant helper functions in icmpv6.go are called.
func (tun *tunDevice) read() error {
mtu := tun.mtu
if tun.iface.IsTAP() {
@ -109,6 +125,9 @@ func (tun *tunDevice) read() error {
}
}
// Closes the TUN/TAP adapter. This is only usually called when the Yggdrasil
// process stops. Typically this operation will happen quickly, but on macOS
// it can block until a read operation is completed.
func (tun *tunDevice) close() error {
if tun.iface == nil {
return nil