Unify MTU datatypes across the codebase

The codebase uses int and unit16 to represent MTU randomly. This change
unifies it to a MTU type from types package, which is currently uint16.

src/config/config.go

@@ -22,8 +22,11 @@ import (
 
 	"github.com/yggdrasil-network/yggdrasil-go/src/crypto"
 	"github.com/yggdrasil-network/yggdrasil-go/src/defaults"
+	"github.com/yggdrasil-network/yggdrasil-go/src/types"
 )
 
+type MTU = types.MTU
+
 // NodeState represents the active and previous configuration of an Yggdrasil
 // node. A NodeState object is returned when starting an Yggdrasil node. Note
 // that this structure and related functions are likely to disappear soon.
@@ -71,7 +74,7 @@ type NodeConfig struct {
 	SigningPrivateKey           string                 `comment:"Your private signing key. DO NOT share this with anyone!"`
 	LinkLocalTCPPort            uint16                 `comment:"The port number to be used for the link-local TCP listeners for the\nconfigured MulticastInterfaces. This option does not affect listeners\nspecified in the Listen option. Unless you plan to firewall link-local\ntraffic, it is best to leave this as the default value of 0. This\noption cannot currently be changed by reloading config during runtime."`
 	IfName                      string                 `comment:"Local network interface name for TUN adapter, or \"auto\" to select\nan interface automatically, or \"none\" to run without TUN."`
-	IfMTU                       int                    `comment:"Maximum Transmission Unit (MTU) size for your local TUN interface.\nDefault is the largest supported size for your platform. The lowest\npossible value is 1280."`
+	IfMTU                       MTU                    `comment:"Maximum Transmission Unit (MTU) size for your local TUN interface.\nDefault is the largest supported size for your platform. The lowest\npossible value is 1280."`
 	SessionFirewall             SessionFirewall        `comment:"The session firewall controls who can send/receive network traffic\nto/from. This is useful if you want to protect this node without\nresorting to using a real firewall. This does not affect traffic\nbeing routed via this node to somewhere else. Rules are prioritised as\nfollows: blacklist, whitelist, always allow outgoing, direct, remote."`
 	TunnelRouting               TunnelRouting          `comment:"Allow tunneling non-Yggdrasil traffic over Yggdrasil. This effectively\nallows you to use Yggdrasil to route to, or to bridge other networks,\nsimilar to a VPN tunnel. Tunnelling works between any two nodes and\ndoes not require them to be directly peered."`
 	SwitchOptions               SwitchOptions          `comment:"Advanced options for tuning the switch. Normally you will not need\nto edit these options."`

src/defaults/defaults.go

@@ -1,5 +1,7 @@
 package defaults
 
+import "github.com/yggdrasil-network/yggdrasil-go/src/types"
+
 // Defines which parameters are expected by default for configuration on a
 // specific platform. These values are populated in the relevant defaults_*.go
 // for the platform being targeted. They must be set.
@@ -14,7 +16,7 @@ type platformDefaultParameters struct {
 	DefaultMulticastInterfaces []string
 
 	// TUN/TAP
-	MaximumIfMTU  int
-	DefaultIfMTU  int
+	MaximumIfMTU  types.MTU
+	DefaultIfMTU  types.MTU
 	DefaultIfName string
 }

src/tuntap/iface.go

@@ -55,7 +55,7 @@ type tunReader struct {
 
 func (r *tunReader) _read() {
 	// Get a slice to store the packet in
-	recvd := util.ResizeBytes(util.GetBytes(), r.tun.mtu+TUN_OFFSET_BYTES)
+	recvd := util.ResizeBytes(util.GetBytes(), int(r.tun.mtu)+TUN_OFFSET_BYTES)
 	// Wait for a packet to be delivered to us through the TUN adapter
 	n, err := r.tun.iface.Read(recvd, TUN_OFFSET_BYTES)
 	if n <= TUN_OFFSET_BYTES || err != nil {

src/tuntap/tun.go

@@ -25,8 +25,11 @@ import (
 	"github.com/yggdrasil-network/yggdrasil-go/src/crypto"
 	"github.com/yggdrasil-network/yggdrasil-go/src/defaults"
 	"github.com/yggdrasil-network/yggdrasil-go/src/yggdrasil"
+	"github.com/yggdrasil-network/yggdrasil-go/src/types"
 )
 
+type MTU = types.MTU
+
 const tun_IPv6_HEADER_LENGTH = 40
 
 // TunAdapter represents a running TUN interface and extends the
@@ -46,7 +49,7 @@ type TunAdapter struct {
 	subnet      address.Subnet
 	ckr         cryptokey
 	icmpv6      ICMPv6
-	mtu         int
+	mtu         MTU
 	iface       tun.Device
 	phony.Inbox // Currently only used for _handlePacket from the reader, TODO: all the stuff that currently needs a mutex below
 	//mutex        sync.RWMutex // Protects the below
@@ -63,7 +66,7 @@ type TunOptions struct {
 
 // Gets the maximum supported MTU for the platform based on the defaults in
 // defaults.GetDefaults().
-func getSupportedMTU(mtu int) int {
+func getSupportedMTU(mtu MTU) MTU {
 	if mtu < 1280 {
 		return 1280
 	}
@@ -85,7 +88,7 @@ func (tun *TunAdapter) Name() string {
 // MTU gets the adapter's MTU. This can range between 1280 and 65535, although
 // the maximum value is determined by your platform. The returned value will
 // never exceed that of MaximumMTU().
-func (tun *TunAdapter) MTU() int {
+func (tun *TunAdapter) MTU() MTU {
 	return getSupportedMTU(tun.mtu)
 }
 
@@ -96,14 +99,14 @@ func DefaultName() string {
 
 // DefaultMTU gets the default TUN interface MTU for your platform. This can
 // be as high as MaximumMTU(), depending on platform, but is never lower than 1280.
-func DefaultMTU() int {
+func DefaultMTU() MTU {
 	return defaults.GetDefaults().DefaultIfMTU
 }
 
 // MaximumMTU returns the maximum supported TUN interface MTU for your
 // platform. This can be as high as 65535, depending on platform, but is never
 // lower than 1280.
-func MaximumMTU() int {
+func MaximumMTU() MTU {
 	return defaults.GetDefaults().MaximumIfMTU
 }
 
@@ -165,7 +168,7 @@ func (tun *TunAdapter) _start() error {
 	if tun.MTU() != current.IfMTU {
 		tun.log.Warnf("Warning: Interface MTU %d automatically adjusted to %d (supported range is 1280-%d)", current.IfMTU, tun.MTU(), MaximumMTU())
 	}
-	tun.core.SetMaximumSessionMTU(uint16(tun.MTU()))
+	tun.core.SetMaximumSessionMTU(tun.MTU())
 	tun.isOpen = true
 	go tun.handler()
 	tun.reader.Act(nil, tun.reader._read) // Start the reader

src/tuntap/tun_bsd.go

@@ -73,14 +73,14 @@ type in6_ifreq_lifetime struct {
 }
 
 // Configures the TUN adapter with the correct IPv6 address and MTU.
-func (tun *TunAdapter) setup(ifname string, addr string, mtu int) error {
-	iface, err := wgtun.CreateTUN(ifname, mtu)
+func (tun *TunAdapter) setup(ifname string, addr string, mtu MTU) error {
+	iface, err := wgtun.CreateTUN(ifname, int(mtu))
 	if err != nil {
 		panic(err)
 	}
 	tun.iface = iface
 	if mtu, err := iface.MTU(); err == nil {
-		tun.mtu = getSupportedMTU(mtu)
+		tun.mtu = getSupportedMTU(MTU(mtu))
 	} else {
 		tun.mtu = 0
 	}

src/tuntap/tun_darwin.go

@@ -16,17 +16,17 @@ import (
 )
 
 // Configures the "utun" adapter with the correct IPv6 address and MTU.
-func (tun *TunAdapter) setup(ifname string, addr string, mtu int) error {
+func (tun *TunAdapter) setup(ifname string, addr string, mtu MTU) error {
 	if ifname == "auto" {
 		ifname = "utun"
 	}
-	iface, err := wgtun.CreateTUN(ifname, mtu)
+	iface, err := wgtun.CreateTUN(ifname, int(mtu))
 	if err != nil {
 		panic(err)
 	}
 	tun.iface = iface
 	if mtu, err := iface.MTU(); err == nil {
-		tun.mtu = getSupportedMTU(mtu)
+		tun.mtu = getSupportedMTU(MTU(mtu))
 	} else {
 		tun.mtu = 0
 	}

src/tuntap/tun_linux.go

@@ -10,17 +10,17 @@ import (
 )
 
 // Configures the TUN adapter with the correct IPv6 address and MTU.
-func (tun *TunAdapter) setup(ifname string, addr string, mtu int) error {
+func (tun *TunAdapter) setup(ifname string, addr string, mtu MTU) error {
 	if ifname == "auto" {
 		ifname = "\000"
 	}
-	iface, err := wgtun.CreateTUN(ifname, mtu)
+	iface, err := wgtun.CreateTUN(ifname, int(mtu))
 	if err != nil {
 		panic(err)
 	}
 	tun.iface = iface
 	if mtu, err := iface.MTU(); err == nil {
-		tun.mtu = getSupportedMTU(mtu)
+		tun.mtu = getSupportedMTU(MTU(mtu))
 	} else {
 		tun.mtu = 0
 	}
@@ -43,7 +43,7 @@ func (tun *TunAdapter) setupAddress(addr string) error {
 	if err := netlink.AddrAdd(nlintf, nladdr); err != nil {
 		return err
 	}
-	if err := netlink.LinkSetMTU(nlintf, tun.mtu); err != nil {
+	if err := netlink.LinkSetMTU(nlintf, int(tun.mtu)); err != nil {
 		return err
 	}
 	if err := netlink.LinkSetUp(nlintf); err != nil {

src/tuntap/tun_windows.go

@@ -19,7 +19,7 @@ import (
 // This is to catch Windows platforms
 
 // Configures the TUN adapter with the correct IPv6 address and MTU.
-func (tun *TunAdapter) setup(ifname string, addr string, mtu int) error {
+func (tun *TunAdapter) setup(ifname string, addr string, mtu MTU) error {
 	if ifname == "auto" {
 		ifname = defaults.GetDefaults().DefaultIfName
 	}
@@ -30,7 +30,7 @@ func (tun *TunAdapter) setup(ifname string, addr string, mtu int) error {
 		if guid, err = windows.GUIDFromString("{8f59971a-7872-4aa6-b2eb-061fc4e9d0a7}"); err != nil {
 			return err
 		}
-		if iface, err = wgtun.CreateTUNWithRequestedGUID(ifname, &guid, mtu); err != nil {
+		if iface, err = wgtun.CreateTUNWithRequestedGUID(ifname, &guid, int(mtu)); err != nil {
 			return err
 		}
 		tun.iface = iface
@@ -42,15 +42,15 @@ func (tun *TunAdapter) setup(ifname string, addr string, mtu int) error {
 			tun.log.Errorln("Failed to set up TUN MTU:", err)
 			return err
 		}
-		if mtu, err = iface.MTU(); err == nil {
-			tun.mtu = mtu
+		if mtu, err := iface.MTU(); err == nil {
+			tun.mtu = MTU(mtu)
 		}
 		return nil
 	})
 }
 
 // Sets the MTU of the TAP adapter.
-func (tun *TunAdapter) setupMTU(mtu int) error {
+func (tun *TunAdapter) setupMTU(mtu MTU) error {
 	if tun.iface == nil || tun.Name() == "" {
 		return errors.New("Can't configure MTU as TUN adapter is not present")
 	}

src/types/types.go

@@ -0,0 +1,3 @@
+package types
+
+type MTU uint16

src/yggdrasil/api.go

@@ -99,7 +99,7 @@ type Session struct {
 	Coords      []uint64         // The coordinates of the remote node
 	BytesSent   uint64           // Bytes sent to the session
 	BytesRecvd  uint64           // Bytes received from the session
-	MTU         uint16           // The maximum supported message size of the session
+	MTU         MTU              // The maximum supported message size of the session
 	Uptime      time.Duration    // How long this session has been active for
 	WasMTUFixed bool             // This field is no longer used
 }
@@ -364,8 +364,8 @@ func (c *Core) SetNodeInfo(nodeinfo interface{}, nodeinfoprivacy bool) {
 }
 
 // GetMaximumSessionMTU returns the maximum allowed session MTU size.
-func (c *Core) GetMaximumSessionMTU() uint16 {
-	var mtu uint16
+func (c *Core) GetMaximumSessionMTU() MTU {
+	var mtu MTU
 	phony.Block(&c.router, func() {
 		mtu = c.router.sessions.myMaximumMTU
 	})
@@ -375,7 +375,7 @@ func (c *Core) GetMaximumSessionMTU() uint16 {
 // SetMaximumSessionMTU sets the maximum allowed session MTU size. The default
 // value is 65535 bytes. Session pings will be sent to update all open sessions
 // if the MTU has changed.
-func (c *Core) SetMaximumSessionMTU(mtu uint16) {
+func (c *Core) SetMaximumSessionMTU(mtu MTU) {
 	phony.Block(&c.router, func() {
 		if c.router.sessions.myMaximumMTU != mtu {
 			c.router.sessions.myMaximumMTU = mtu

src/yggdrasil/conn.go

@@ -8,10 +8,13 @@ import (
 
 	"github.com/yggdrasil-network/yggdrasil-go/src/crypto"
 	"github.com/yggdrasil-network/yggdrasil-go/src/util"
+	"github.com/yggdrasil-network/yggdrasil-go/src/types"
 
 	"github.com/Arceliar/phony"
 )
 
+type MTU = types.MTU
+
 // ConnError implements the net.Error interface
 type ConnError struct {
 	error
@@ -65,7 +68,7 @@ type Conn struct {
 	nodeID        *crypto.NodeID
 	nodeMask      *crypto.NodeID
 	session       *sessionInfo
-	mtu           uint16
+	mtu           MTU
 	readCallback  func([]byte)
 	readBuffer    chan []byte
 }
@@ -93,7 +96,7 @@ func (c *Conn) String() string {
 	return s
 }
 
-func (c *Conn) setMTU(from phony.Actor, mtu uint16) {
+func (c *Conn) setMTU(from phony.Actor, mtu MTU) {
 	c.Act(from, func() { c.mtu = mtu })
 }
 

src/yggdrasil/session.go

@@ -36,8 +36,8 @@ type sessionInfo struct {
 	myHandle      crypto.Handle       //
 	theirNonce    crypto.BoxNonce     //
 	myNonce       crypto.BoxNonce     //
-	theirMTU      uint16              //
-	myMTU         uint16              //
+	theirMTU      MTU                 //
+	myMTU         MTU                 //
 	wasMTUFixed   bool                // Was the MTU fixed by a receive error?
 	timeOpened    time.Time           // Time the session was opened
 	time          time.Time           // Time we last received a packet
@@ -63,7 +63,7 @@ type sessionPing struct {
 	Coords      []byte           //
 	Tstamp      int64            // unix time, but the only real requirement is that it increases
 	IsPong      bool             //
-	MTU         uint16           //
+	MTU         MTU              //
 }
 
 // Updates session info in response to a ping, after checking that the ping is OK.
@@ -117,7 +117,7 @@ type sessions struct {
 	lastCleanup      time.Time
 	isAllowedHandler func(pubkey *crypto.BoxPubKey, initiator bool) bool // Returns true or false if session setup is allowed
 	isAllowedMutex   sync.RWMutex                                        // Protects the above
-	myMaximumMTU     uint16                                              // Maximum allowed session MTU
+	myMaximumMTU     MTU                                                 // Maximum allowed session MTU
 	permShared       map[crypto.BoxPubKey]*crypto.BoxSharedKey           // Maps known permanent keys to their shared key, used by DHT a lot
 	sinfos           map[crypto.Handle]*sessionInfo                      // Maps handle onto session info
 	byTheirPerm      map[crypto.BoxPubKey]*crypto.Handle                 // Maps theirPermPub onto handle
@@ -385,7 +385,7 @@ func (ss *sessions) handlePing(ping *sessionPing) {
 // Get the MTU of the session.
 // Will be equal to the smaller of this node's MTU or the remote node's MTU.
 // If sending over links with a maximum message size (this was a thing with the old UDP code), it could be further lowered, to a minimum of 1280.
-func (sinfo *sessionInfo) _getMTU() uint16 {
+func (sinfo *sessionInfo) _getMTU() MTU {
 	if sinfo.theirMTU == 0 || sinfo.myMTU == 0 {
 		return 0
 	}

src/yggdrasil/wire.go

@@ -380,7 +380,7 @@ func (p *sessionPing) decode(bs []byte) bool {
 	if pType == wire_SessionPong {
 		p.IsPong = true
 	}
-	p.MTU = uint16(mtu)
+	p.MTU = MTU(mtu)
 	return true
 }