Beginning work on TUN interface

And outbound routing

I am not entirely convinced the use of net.IP is a good idea,
since the internal representation of net.IP is a byte slice
and all constructor functions in "net" return 16 byte slices
(padded for IPv4), while the use in this project uses 4 byte slices.
Which may be confusing.

9 files changed, 290 insertions, 62 deletions

diff --git a/src/config.go b/src/config.go
index 62af67a..a61b940 100644
--- a/src/config.go
+++ b/src/config.go
@@ -7,6 +7,8 @@ import (
 	"io"
 	"log"
 	"net"
+	"strconv"
+	"time"
 )
 
 /* todo : use real error code
@@ -16,6 +18,7 @@ const (
 	ipcErrorNoPeer            = 0
 	ipcErrorNoKeyValue        = 1
 	ipcErrorInvalidKey        = 2
+	ipcErrorInvalidValue      = 2
 	ipcErrorInvalidPrivateKey = 3
 	ipcErrorInvalidPublicKey  = 4
 	ipcErrorInvalidPort       = 5
@@ -34,18 +37,16 @@ func (s *IPCError) ErrorCode() int {
 	return s.Code
 }
 
-// Writes the configuration to the socket
 func ipcGetOperation(socket *bufio.ReadWriter, dev *Device) {
 
 }
 
-// Creates new config, from old and socket message
-func ipcSetOperation(dev *Device, socket *bufio.ReadWriter) *IPCError {
+func ipcSetOperation(device *Device, socket *bufio.ReadWriter) *IPCError {
 
 	scanner := bufio.NewScanner(socket)
 
-	dev.mutex.Lock()
-	defer dev.mutex.Unlock()
+	device.mutex.Lock()
+	defer device.mutex.Unlock()
 
 	for scanner.Scan() {
 		var key string
@@ -71,16 +72,16 @@ func ipcSetOperation(dev *Device, socket *bufio.ReadWriter) *IPCError {
 
 		case "private_key":
 			if value == "" {
-				dev.privateKey = NoisePrivateKey{}
+				device.privateKey = NoisePrivateKey{}
 			} else {
-				err := dev.privateKey.FromHex(value)
+				err := device.privateKey.FromHex(value)
 				if err != nil {
 					return &IPCError{Code: ipcErrorInvalidPrivateKey}
 				}
 			}
 
 		case "listen_port":
-			_, err := fmt.Sscanf(value, "%ud", &dev.listenPort)
+			_, err := fmt.Sscanf(value, "%ud", &device.listenPort)
 			if err != nil {
 				return &IPCError{Code: ipcErrorInvalidPort}
 			}
@@ -94,7 +95,7 @@ func ipcSetOperation(dev *Device, socket *bufio.ReadWriter) *IPCError {
 			if err != nil {
 				return &IPCError{Code: ipcErrorInvalidPublicKey}
 			}
-			found, ok := dev.peers[pubKey]
+			found, ok := device.peers[pubKey]
 			if ok {
 				peer = found
 			} else {
@@ -102,14 +103,16 @@ func ipcSetOperation(dev *Device, socket *bufio.ReadWriter) *IPCError {
 					publicKey: pubKey,
 				}
 				peer = newPeer
-				dev.peers[pubKey] = newPeer
+				device.peers[pubKey] = newPeer
 			}
 
 		case "replace_peers":
 			if key == "true" {
-				dev.RemoveAllPeers()
+				device.RemoveAllPeers()
+			} else if key == "false" {
+			} else {
+				return &IPCError{Code: ipcErrorInvalidValue}
 			}
-			// todo: else fail
 
 		default:
 			/* Peer configuration */
@@ -122,7 +125,7 @@ func ipcSetOperation(dev *Device, socket *bufio.ReadWriter) *IPCError {
 
 			case "remove":
 				peer.mutex.Lock()
-				dev.RemovePeer(peer.publicKey)
+				device.RemovePeer(peer.publicKey)
 				peer = nil
 
 			case "preshared_key":
@@ -145,15 +148,29 @@ func ipcSetOperation(dev *Device, socket *bufio.ReadWriter) *IPCError {
 				peer.mutex.Unlock()
 
 			case "persistent_keepalive_interval":
-				func() {
-					peer.mutex.Lock()
-					defer peer.mutex.Unlock()
-				}()
+				secs, err := strconv.ParseInt(value, 10, 64)
+				if secs < 0 || err != nil {
+					return &IPCError{Code: ipcErrorInvalidValue}
+				}
+				peer.mutex.Lock()
+				peer.persistentKeepaliveInterval = time.Duration(secs) * time.Second
+				peer.mutex.Unlock()
 
 			case "replace_allowed_ips":
-				// remove peer from trie
+				if key == "true" {
+					device.routingTable.RemovePeer(peer)
+				} else if key == "false" {
+				} else {
+					return &IPCError{Code: ipcErrorInvalidValue}
+				}
 
 			case "allowed_ip":
+				_, network, err := net.ParseCIDR(value)
+				if err != nil {
+					return &IPCError{Code: ipcErrorInvalidValue}
+				}
+				ones, _ := network.Mask.Size()
+				device.routingTable.Insert(network.IP, uint(ones), peer)
 
 			/* Invalid key */
 
diff --git a/src/ip.go b/src/ip.go
new file mode 100644
index 0000000..3137891
--- /dev/null
+++ b/src/ip.go
@@ -0,0 +1,17 @@
+package main
+
+import (
+	"net"
+)
+
+const (
+	IPv4version   = 4
+	IPv4offsetSrc = 12
+	IPv4offsetDst = IPv4offsetSrc + net.IPv4len
+)
+
+const (
+	IPv6version   = 6
+	IPv6offsetSrc = 8
+	IPv6offsetDst = IPv6offsetSrc + net.IPv6len
+)
diff --git a/src/main.go b/src/main.go
index 0f5016d..af336f0 100644
--- a/src/main.go
+++ b/src/main.go
@@ -1,11 +1,33 @@
 package main
 
+import "fmt"
+
+func main() {
+	fd, err := CreateTUN("test0")
+	fmt.Println(fd, err)
+
+	queue := make(chan []byte, 1000)
+
+	var device Device
+
+	go OutgoingRoutingWorker(&device, queue)
+
+	for {
+		tmp := make([]byte, 1<<16)
+		n, err := fd.Read(tmp)
+		if err != nil {
+			break
+		}
+		queue <- tmp[:n]
+	}
+}
+
+/*
 import (
 	"fmt"
 	"log"
 	"net"
 )
-
 func main() {
 	l, err := net.Listen("unix", "/var/run/wireguard/wg0.sock")
 	if err != nil {
@@ -24,5 +46,5 @@ func main() {
 			fmt.Println(err)
 		}(fd)
 	}
-
 }
+*/
diff --git a/src/peer.go b/src/peer.go
index 7b2b2a6..db5e99f 100644
--- a/src/peer.go
+++ b/src/peer.go
@@ -3,6 +3,7 @@ package main
 import (
 	"net"
 	"sync"
+	"time"
 )
 
 type KeyPair struct {
@@ -13,8 +14,9 @@ type KeyPair struct {
 }
 
 type Peer struct {
-	mutex        sync.RWMutex
-	publicKey    NoisePublicKey
-	presharedKey NoiseSymmetricKey
-	endpoint     net.IP
+	mutex                       sync.RWMutex
+	publicKey                   NoisePublicKey
+	presharedKey                NoiseSymmetricKey
+	endpoint                    net.IP
+	persistentKeepaliveInterval time.Duration
 }
diff --git a/src/routing.go b/src/routing.go
index 99b180c..0aa111c 100644
--- a/src/routing.go
+++ b/src/routing.go
@@ -1,13 +1,12 @@
 package main
 
 import (
+	"errors"
+	"fmt"
+	"net"
 	"sync"
 )
 
-/* Thread-safe high level functions for cryptkey routing.
- *
- */
-
 type RoutingTable struct {
 	IPv4  *Trie
 	IPv6  *Trie
@@ -20,3 +19,51 @@ func (table *RoutingTable) RemovePeer(peer *Peer) {
 	table.IPv4 = table.IPv4.RemovePeer(peer)
 	table.IPv6 = table.IPv6.RemovePeer(peer)
 }
+
+func (table *RoutingTable) Insert(ip net.IP, cidr uint, peer *Peer) {
+	table.mutex.Lock()
+	defer table.mutex.Unlock()
+
+	switch len(ip) {
+	case net.IPv6len:
+		table.IPv6 = table.IPv6.Insert(ip, cidr, peer)
+	case net.IPv4len:
+		table.IPv4 = table.IPv4.Insert(ip, cidr, peer)
+	default:
+		panic(errors.New("Inserting unknown address type"))
+	}
+}
+
+func (table *RoutingTable) LookupIPv4(address []byte) *Peer {
+	table.mutex.RLock()
+	defer table.mutex.RUnlock()
+	return table.IPv4.Lookup(address)
+}
+
+func (table *RoutingTable) LookupIPv6(address []byte) *Peer {
+	table.mutex.RLock()
+	defer table.mutex.RUnlock()
+	return table.IPv6.Lookup(address)
+}
+
+func OutgoingRoutingWorker(device *Device, queue chan []byte) {
+	for {
+		packet := <-queue
+		switch packet[0] >> 4 {
+
+		case IPv4version:
+			dst := packet[IPv4offsetDst : IPv4offsetDst+net.IPv4len]
+			peer := device.routingTable.LookupIPv4(dst)
+			fmt.Println("IPv4", peer)
+
+		case IPv6version:
+			dst := packet[IPv6offsetDst : IPv6offsetDst+net.IPv6len]
+			peer := device.routingTable.LookupIPv6(dst)
+			fmt.Println("IPv6", peer)
+
+		default:
+			// todo: log
+			fmt.Println("Unknown IP version")
+		}
+	}
+}
diff --git a/src/trie.go b/src/trie.go
index 31a4d92..746c1b4 100644
--- a/src/trie.go
+++ b/src/trie.go
@@ -1,5 +1,9 @@
 package main
 
+import (
+	"net"
+)
+
 /* Binary trie
  *
  * Syncronization done seperatly
@@ -22,13 +26,13 @@ type Trie struct {
 /* Finds length of matching prefix
  * Maybe there is a faster way
  *
- * Assumption: len(s1) == len(s2)
+ * Assumption: len(ip1) == len(ip2)
  */
-func commonBits(s1 []byte, s2 []byte) uint {
+func commonBits(ip1 net.IP, ip2 net.IP) uint {
 	var i uint
-	size := uint(len(s1))
+	size := uint(len(ip1))
 	for i = 0; i < size; i += 1 {
-		v := s1[i] ^ s2[i]
+		v := ip1[i] ^ ip2[i]
 		if v != 0 {
 			v >>= 1
 			if v == 0 {
@@ -93,17 +97,17 @@ func (node *Trie) RemovePeer(p *Peer) *Trie {
 	return node.child[0]
 }
 
-func (node *Trie) choose(key []byte) byte {
-	return (key[node.bit_at_byte] >> node.bit_at_shift) & 1
+func (node *Trie) choose(ip net.IP) byte {
+	return (ip[node.bit_at_byte] >> node.bit_at_shift) & 1
 }
 
-func (node *Trie) Insert(key []byte, cidr uint, peer *Peer) *Trie {
+func (node *Trie) Insert(ip net.IP, cidr uint, peer *Peer) *Trie {
 
 	// At leaf
 
 	if node == nil {
 		return &Trie{
-			bits:         key,
+			bits:         ip,
 			peer:         peer,
 			cidr:         cidr,
 			bit_at_byte:  cidr / 8,
@@ -113,21 +117,21 @@ func (node *Trie) Insert(key []byte, cidr uint, peer *Peer) *Trie {
 
 	// Traverse deeper
 
-	common := commonBits(node.bits, key)
+	common := commonBits(node.bits, ip)
 	if node.cidr <= cidr && common >= node.cidr {
 		if node.cidr == cidr {
 			node.peer = peer
 			return node
 		}
-		bit := node.choose(key)
-		node.child[bit] = node.child[bit].Insert(key, cidr, peer)
+		bit := node.choose(ip)
+		node.child[bit] = node.child[bit].Insert(ip, cidr, peer)
 		return node
 	}
 
 	// Split node
 
 	newNode := &Trie{
-		bits:         key,
+		bits:         ip,
 		peer:         peer,
 		cidr:         cidr,
 		bit_at_byte:  cidr / 8,
@@ -147,31 +151,31 @@ func (node *Trie) Insert(key []byte, cidr uint, peer *Peer) *Trie {
 	// Create new parent for node & newNode
 
 	parent := &Trie{
-		bits:         key,
+		bits:         ip,
 		peer:         nil,
 		cidr:         cidr,
 		bit_at_byte:  cidr / 8,
 		bit_at_shift: 7 - (cidr % 8),
 	}
 
-	bit := parent.choose(key)
+	bit := parent.choose(ip)
 	parent.child[bit] = newNode
 	parent.child[bit^1] = node
 
 	return parent
 }
 
-func (node *Trie) Lookup(key []byte) *Peer {
+func (node *Trie) Lookup(ip net.IP) *Peer {
 	var found *Peer
-	size := uint(len(key))
-	for node != nil && commonBits(node.bits, key) >= node.cidr {
+	size := uint(len(ip))
+	for node != nil && commonBits(node.bits, ip) >= node.cidr {
 		if node.peer != nil {
 			found = node.peer
 		}
 		if node.bit_at_byte == size {
 			break
 		}
-		bit := node.choose(key)
+		bit := node.choose(ip)
 		node = node.child[bit]
 	}
 	return found
diff --git a/src/trie_test.go b/src/trie_test.go
index 35af0aa..9d53df3 100644
--- a/src/trie_test.go
+++ b/src/trie_test.go
@@ -1,6 +1,8 @@
 package main
 
 import (
+	"math/rand"
+	"net"
 	"testing"
 )
 
@@ -55,6 +57,49 @@ func TestCommonBits(t *testing.T) {
 	}
 }
 
+func benchmarkTrie(peerNumber int, addressNumber int, addressLength int, b *testing.B) {
+	var trie *Trie
+	var peers []*Peer
+
+	rand.Seed(1)
+
+	const AddressLength = 4
+
+	for n := 0; n < peerNumber; n += 1 {
+		peers = append(peers, &Peer{})
+	}
+
+	for n := 0; n < addressNumber; n += 1 {
+		var addr [AddressLength]byte
+		rand.Read(addr[:])
+		cidr := uint(rand.Uint32() % (AddressLength * 8))
+		index := rand.Int() % peerNumber
+		trie = trie.Insert(addr[:], cidr, peers[index])
+	}
+
+	for n := 0; n < b.N; n += 1 {
+		var addr [AddressLength]byte
+		rand.Read(addr[:])
+		trie.Lookup(addr[:])
+	}
+}
+
+func BenchmarkTrieIPv4Peers100Addresses1000(b *testing.B) {
+	benchmarkTrie(100, 1000, net.IPv4len, b)
+}
+
+func BenchmarkTrieIPv4Peers10Addresses10(b *testing.B) {
+	benchmarkTrie(10, 10, net.IPv4len, b)
+}
+
+func BenchmarkTrieIPv6Peers100Addresses1000(b *testing.B) {
+	benchmarkTrie(100, 1000, net.IPv6len, b)
+}
+
+func BenchmarkTrieIPv6Peers10Addresses10(b *testing.B) {
+	benchmarkTrie(10, 10, net.IPv6len, b)
+}
+
 /* Test ported from kernel implementation:
  * selftest/routingtable.h
  */
@@ -91,10 +136,10 @@ func TestTrieIPv4(t *testing.T) {
 	insert(b, 192, 168, 4, 4, 32)
 	insert(c, 192, 168, 0, 0, 16)
 	insert(d, 192, 95, 5, 64, 27)
-	insert(c, 192, 95, 5, 65, 27) /* replaces previous entry, and maskself is required */
+	insert(c, 192, 95, 5, 65, 27)
 	insert(e, 0, 0, 0, 0, 0)
 	insert(g, 64, 15, 112, 0, 20)
-	insert(h, 64, 15, 123, 211, 25) /* maskself is required */
+	insert(h, 64, 15, 123, 211, 25)
 	insert(a, 10, 0, 0, 0, 25)
 	insert(b, 10, 0, 0, 128, 25)
 	insert(a, 10, 1, 0, 0, 30)
@@ -186,20 +231,6 @@ func TestTrieIPv6(t *testing.T) {
 		}
 	}
 
-	/*
-		assertNEQ := func(peer *Peer, a, b, c, d uint32) {
-			var addr []byte
-			addr = append(addr, expand(a)...)
-			addr = append(addr, expand(b)...)
-			addr = append(addr, expand(c)...)
-			addr = append(addr, expand(d)...)
-			p := trie.Lookup(addr)
-			if p == peer {
-				t.Error("Assert NEQ failed")
-			}
-		}
-	*/
-
 	insert(d, 0x26075300, 0x60006b00, 0, 0xc05f0543, 128)
 	insert(c, 0x26075300, 0x60006b00, 0, 0, 64)
 	insert(e, 0, 0, 0, 0, 0)
diff --git a/src/tun.go b/src/tun.go
new file mode 100644
index 0000000..1a8bb82
--- /dev/null
+++ b/src/tun.go
@@ -0,0 +1,8 @@
+package main
+
+type TUN interface {
+	Read([]byte) (int, error)
+	Write([]byte) (int, error)
+	Name() string
+	MTU() uint
+}
diff --git a/src/tun_linux.go b/src/tun_linux.go
new file mode 100644
index 0000000..d545dfa
--- /dev/null
+++ b/src/tun_linux.go
@@ -0,0 +1,80 @@
+package main
+
+import (
+	"encoding/binary"
+	"errors"
+	"os"
+	"strings"
+	"syscall"
+	"unsafe"
+)
+
+/* Platform dependent functions for interacting with
+ * TUN devices on linux systems
+ *
+ */
+
+const CloneDevicePath = "/dev/net/tun"
+
+const (
+	IFF_NO_PI = 0x1000
+	IFF_TUN   = 0x1
+	IFNAMSIZ  = 0x10
+	TUNSETIFF = 0x400454CA
+)
+
+type NativeTun struct {
+	fd   *os.File
+	name string
+	mtu  uint
+}
+
+func (tun *NativeTun) Name() string {
+	return tun.name
+}
+
+func (tun *NativeTun) MTU() uint {
+	return tun.mtu
+}
+
+func (tun *NativeTun) Write(d []byte) (int, error) {
+	return tun.fd.Write(d)
+}
+
+func (tun *NativeTun) Read(d []byte) (int, error) {
+	return tun.fd.Read(d)
+}
+
+func CreateTUN(name string) (TUN, error) {
+	// Open clone device
+	fd, err := os.OpenFile(CloneDevicePath, os.O_RDWR, 0)
+	if err != nil {
+		return nil, err
+	}
+
+	// Prepare ifreq struct
+	var ifr [18]byte
+	var flags uint16 = IFF_TUN | IFF_NO_PI
+	nameBytes := []byte(name)
+	if len(nameBytes) >= IFNAMSIZ {
+		return nil, errors.New("Name size too long")
+	}
+	copy(ifr[:], nameBytes)
+	binary.LittleEndian.PutUint16(ifr[16:], flags)
+
+	// Create new device
+	_, _, errno := syscall.Syscall(syscall.SYS_IOCTL,
+		uintptr(fd.Fd()), uintptr(TUNSETIFF),
+		uintptr(unsafe.Pointer(&ifr[0])))
+	if errno != 0 {
+		return nil, errors.New("Failed to create tun, ioctl call failed")
+	}
+
+	// Read name of interface
+	newName := string(ifr[:])
+	newName = newName[:strings.Index(newName, "\000")]
+	return &NativeTun{
+		fd:   fd,
+		name: newName,
+	}, nil
+}