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/* Copyright 2015-2016 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved. */
package main
import (
"crypto/rand"
"encoding/base64"
"encoding/binary"
"log"
"net"
"time"
"github.com/dchest/blake2s"
"github.com/titanous/noise"
"golang.org/x/net/icmp"
"golang.org/x/net/ipv4"
)
func ipChecksum(buf []byte) uint16 {
sum := uint32(0)
for ; len(buf) >= 2; buf = buf[2:] {
sum += uint32(buf[0])<<8 | uint32(buf[1])
}
if len(buf) > 0 {
sum += uint32(buf[0]) << 8
}
for sum > 0xffff {
sum = (sum >> 16) + (sum & 0xffff)
}
csum := ^uint16(sum)
if csum == 0 {
csum = 0xffff
}
return csum
}
func main() {
ourPrivate, _ := base64.StdEncoding.DecodeString("WAmgVYXkbT2bCtdcDwolI88/iVi/aV3/PHcUBTQSYmo=")
ourPublic, _ := base64.StdEncoding.DecodeString("K5sF9yESrSBsOXPd6TcpKNgqoy1Ik3ZFKl4FolzrRyI=")
preshared, _ := base64.StdEncoding.DecodeString("FpCyhws9cxwWoV4xELtfJvjJN+zQVRPISllRWgeopVE=")
theirPublic, _ := base64.StdEncoding.DecodeString("qRCwZSKInrMAq5sepfCdaCsRJaoLe5jhtzfiw7CjbwM=")
cs := noise.NewCipherSuite(noise.DH25519, noise.CipherChaChaPoly, noise.HashBLAKE2s)
hs := noise.NewHandshakeState(noise.Config{
CipherSuite: cs,
Random: rand.Reader,
Pattern: noise.HandshakeIK,
Initiator: true,
Prologue: []byte("WireGuard v0 zx2c4 Jason@zx2c4.com"),
PresharedKey: preshared,
StaticKeypair: noise.DHKey{Private: ourPrivate, Public: ourPublic},
PeerStatic: theirPublic,
})
conn, err := net.Dial("udp", "demo.wireguard.io:12913")
if err != nil {
log.Fatalf("error dialing udp socket: %s", err)
}
defer conn.Close()
// write handshake initiation packet
now := time.Now()
tai64n := make([]byte, 12)
binary.BigEndian.PutUint64(tai64n[:], uint64(now.Unix()))
binary.BigEndian.PutUint32(tai64n[8:], uint32(now.UnixNano()))
initiationPacket := make([]byte, 5)
initiationPacket[0] = 1 // Type: Initiation
binary.LittleEndian.PutUint32(initiationPacket[1:], 28) // Sender index: 28 (arbitrary)
initiationPacket, _, _ = hs.WriteMessage(initiationPacket, tai64n)
hasher, _ := blake2s.New(&blake2s.Config{Size: 16, Key: preshared})
hasher.Write(theirPublic)
hasher.Write(initiationPacket)
initiationPacket = append(initiationPacket, hasher.Sum(nil)[:16]...)
initiationPacket = append(initiationPacket, make([]byte, 16)...)
if _, err := conn.Write(initiationPacket); err != nil {
log.Fatalf("error writing initiation packet: %s", err)
}
// read handshake response packet
responsePacket := make([]byte, 89)
n, err := conn.Read(responsePacket)
if err != nil {
log.Fatalf("error reading response packet: %s", err)
}
if n != len(responsePacket) {
log.Fatalf("response packet too short: want %d, got %d", len(responsePacket), n)
}
if responsePacket[0] != 2 { // Type: Response
log.Fatalf("response packet type wrong: want %d, got %d", 2, responsePacket[0])
}
theirIndex := binary.LittleEndian.Uint32(responsePacket[1:])
ourIndex := binary.LittleEndian.Uint32(responsePacket[5:])
if ourIndex != 28 {
log.Fatalf("response packet index wrong: want %d, got %d", 28, ourIndex)
}
payload, sendCipher, receiveCipher, err := hs.ReadMessage(nil, responsePacket[9:57])
if err != nil {
log.Fatalf("error reading handshake message: %s", err)
}
if len(payload) > 0 {
log.Fatalf("unexpected payload: %x", payload)
}
// write ICMP Echo packet
pingMessage, _ := (&icmp.Message{
Type: ipv4.ICMPTypeEcho,
Body: &icmp.Echo{
ID: 921,
Seq: 438,
Data: []byte("WireGuard"),
},
}).Marshal(nil)
pingHeader, err := (&ipv4.Header{
Version: ipv4.Version,
Len: ipv4.HeaderLen,
TotalLen: ipv4.HeaderLen + len(pingMessage),
Protocol: 1, // ICMP
TTL: 20,
Src: net.IPv4(10, 189, 129, 2),
Dst: net.IPv4(10, 189, 129, 1),
}).Marshal()
binary.BigEndian.PutUint16(pingHeader[2:], uint16(ipv4.HeaderLen+len(pingMessage))) // fix the length endianness on BSDs
binary.BigEndian.PutUint16(pingHeader[10:], ipChecksum(append(pingHeader, pingMessage...)))
if err != nil {
panic(err)
}
pingPacket := make([]byte, 13)
pingPacket[0] = 4 // Type: Data
binary.LittleEndian.PutUint32(pingPacket[1:], theirIndex)
binary.LittleEndian.PutUint64(pingPacket[5:], 0) // Nonce
pingPacket = sendCipher.Encrypt(pingPacket, nil, append(pingHeader, pingMessage...))
if _, err := conn.Write(pingPacket); err != nil {
log.Fatalf("error writing ping message: %s", err)
}
// read ICMP Echo Reply packet
replyPacket := make([]byte, 128)
n, err = conn.Read(replyPacket)
if err != nil {
log.Fatalf("error reading ping reply message: %s", err)
}
replyPacket = replyPacket[:n]
if replyPacket[0] != 4 { // Type: Data
log.Fatalf("unexpected reply packet type: %d", replyPacket[0])
}
replyPacket, err = receiveCipher.Decrypt(nil, nil, replyPacket[13:])
if err != nil {
log.Fatalf("error decrypting reply packet: %s", err)
}
replyHeaderLen := int(replyPacket[0]&0x0f) << 2
replyLen := binary.BigEndian.Uint16(replyPacket[2:])
replyMessage, err := icmp.ParseMessage(1, replyPacket[replyHeaderLen:replyLen])
if err != nil {
log.Fatalf("error parsing echo: %s", err)
}
echo, ok := replyMessage.Body.(*icmp.Echo)
if !ok {
log.Fatalf("unexpected reply body type %T", replyMessage.Body)
}
if echo.ID != 921 || echo.Seq != 438 || string(echo.Data) != "WireGuard" {
log.Fatalf("incorrect echo response: %#v", echo)
}
}
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