187 lines
6.9 KiB
Go
187 lines
6.9 KiB
Go
/* Copyright (C) 2015-2020 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved. */
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package main
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import (
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"crypto/rand"
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"encoding/base64"
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"encoding/binary"
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"log"
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"net"
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"time"
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"github.com/titanous/noise"
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"golang.org/x/net/icmp"
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"golang.org/x/net/ipv4"
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"golang.org/x/crypto/blake2s"
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)
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func ipChecksum(buf []byte) uint16 {
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sum := uint32(0)
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for ; len(buf) >= 2; buf = buf[2:] {
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sum += uint32(buf[0])<<8 | uint32(buf[1])
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}
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if len(buf) > 0 {
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sum += uint32(buf[0]) << 8
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}
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for sum > 0xffff {
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sum = (sum >> 16) + (sum & 0xffff)
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}
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csum := ^uint16(sum)
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if csum == 0 {
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csum = 0xffff
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}
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return csum
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}
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func main() {
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ourPrivate, _ := base64.StdEncoding.DecodeString("WAmgVYXkbT2bCtdcDwolI88/iVi/aV3/PHcUBTQSYmo=")
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ourPublic, _ := base64.StdEncoding.DecodeString("K5sF9yESrSBsOXPd6TcpKNgqoy1Ik3ZFKl4FolzrRyI=")
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theirPublic, _ := base64.StdEncoding.DecodeString("qRCwZSKInrMAq5sepfCdaCsRJaoLe5jhtzfiw7CjbwM=")
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preshared, _ := base64.StdEncoding.DecodeString("FpCyhws9cxwWoV4xELtfJvjJN+zQVRPISllRWgeopVE=")
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cs := noise.NewCipherSuite(noise.DH25519, noise.CipherChaChaPoly, noise.HashBLAKE2s)
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hs, _ := noise.NewHandshakeState(noise.Config{
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CipherSuite: cs,
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Random: rand.Reader,
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Pattern: noise.HandshakeIK,
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Initiator: true,
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Prologue: []byte("WireGuard v1 zx2c4 Jason@zx2c4.com"),
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PresharedKey: preshared,
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PresharedKeyPlacement: 2,
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StaticKeypair: noise.DHKey{Private: ourPrivate, Public: ourPublic},
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PeerStatic: theirPublic,
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})
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conn, err := net.Dial("udp", "demo.wireguard.com:12913")
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if err != nil {
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log.Fatalf("error dialing udp socket: %s", err)
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}
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defer conn.Close()
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// write handshake initiation packet
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now := time.Now()
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tai64n := make([]byte, 12)
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binary.BigEndian.PutUint64(tai64n[:], 4611686018427387914+uint64(now.Unix()))
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binary.BigEndian.PutUint32(tai64n[8:], uint32(now.Nanosecond()))
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initiationPacket := make([]byte, 8)
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initiationPacket[0] = 1 // Type: Initiation
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initiationPacket[1] = 0 // Reserved
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initiationPacket[2] = 0 // Reserved
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initiationPacket[3] = 0 // Reserved
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binary.LittleEndian.PutUint32(initiationPacket[4:], 28) // Sender index: 28 (arbitrary)
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initiationPacket, _, _, _ = hs.WriteMessage(initiationPacket, tai64n)
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hasher, _ := blake2s.New256(nil)
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hasher.Write([]byte("mac1----"))
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hasher.Write(theirPublic)
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hasher, _ = blake2s.New128(hasher.Sum(nil))
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hasher.Write(initiationPacket)
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initiationPacket = append(initiationPacket, hasher.Sum(nil)[:16]...)
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initiationPacket = append(initiationPacket, make([]byte, 16)...)
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if _, err := conn.Write(initiationPacket); err != nil {
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log.Fatalf("error writing initiation packet: %s", err)
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}
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// read handshake response packet
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responsePacket := make([]byte, 92)
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n, err := conn.Read(responsePacket)
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if err != nil {
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log.Fatalf("error reading response packet: %s", err)
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}
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if n != len(responsePacket) {
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log.Fatalf("response packet too short: want %d, got %d", len(responsePacket), n)
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}
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if responsePacket[0] != 2 { // Type: Response
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log.Fatalf("response packet type wrong: want %d, got %d", 2, responsePacket[0])
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}
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if responsePacket[1] != 0 || responsePacket[2] != 0 || responsePacket[3] != 0 {
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log.Fatalf("response packet has non-zero reserved fields")
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}
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theirIndex := binary.LittleEndian.Uint32(responsePacket[4:])
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ourIndex := binary.LittleEndian.Uint32(responsePacket[8:])
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if ourIndex != 28 {
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log.Fatalf("response packet index wrong: want %d, got %d", 28, ourIndex)
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}
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payload, sendCipher, receiveCipher, err := hs.ReadMessage(nil, responsePacket[12:60])
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if err != nil {
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log.Fatalf("error reading handshake message: %s", err)
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}
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if len(payload) > 0 {
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log.Fatalf("unexpected payload: %x", payload)
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}
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// write ICMP Echo packet
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pingMessage, _ := (&icmp.Message{
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Type: ipv4.ICMPTypeEcho,
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Body: &icmp.Echo{
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ID: 921,
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Seq: 438,
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Data: []byte("WireGuard"),
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},
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}).Marshal(nil)
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pingHeader, err := (&ipv4.Header{
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Version: ipv4.Version,
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Len: ipv4.HeaderLen,
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TotalLen: ipv4.HeaderLen + len(pingMessage),
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Protocol: 1, // ICMP
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TTL: 20,
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Src: net.IPv4(10, 189, 129, 2),
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Dst: net.IPv4(10, 189, 129, 1),
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}).Marshal()
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binary.BigEndian.PutUint16(pingHeader[2:], uint16(ipv4.HeaderLen+len(pingMessage))) // fix the length endianness on BSDs
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pingData := append(append(pingHeader, pingMessage...), 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0)
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binary.BigEndian.PutUint16(pingData[10:], ipChecksum(pingData))
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pingPacket := make([]byte, 16)
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pingPacket[0] = 4 // Type: Data
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pingPacket[1] = 0 // Reserved
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pingPacket[2] = 0 // Reserved
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pingPacket[3] = 0 // Reserved
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binary.LittleEndian.PutUint32(pingPacket[4:], theirIndex) // Their index
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binary.LittleEndian.PutUint64(pingPacket[8:], 0) // Nonce
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pingPacket = sendCipher.Encrypt(pingPacket, nil, pingData) // Payload data
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if _, err := conn.Write(pingPacket); err != nil {
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log.Fatalf("error writing ping message: %s", err)
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}
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// read ICMP Echo Reply packet
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replyPacket := make([]byte, 80)
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n, err = conn.Read(replyPacket)
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if err != nil {
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log.Fatalf("error reading ping reply message: %s", err)
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}
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replyPacket = replyPacket[:n]
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if replyPacket[0] != 4 { // Type: Data
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log.Fatalf("unexpected reply packet type: %d", replyPacket[0])
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}
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if replyPacket[1] != 0 || replyPacket[2] != 0 || replyPacket[3] != 0 {
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log.Fatalf("reply packet has non-zero reserved fields")
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}
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replyPacket, err = receiveCipher.Decrypt(nil, nil, replyPacket[16:])
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if err != nil {
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log.Fatalf("error decrypting reply packet: %s", err)
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}
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replyHeaderLen := int(replyPacket[0]&0x0f) << 2
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replyLen := binary.BigEndian.Uint16(replyPacket[2:])
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replyMessage, err := icmp.ParseMessage(1, replyPacket[replyHeaderLen:replyLen])
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if err != nil {
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log.Fatalf("error parsing echo: %s", err)
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}
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echo, ok := replyMessage.Body.(*icmp.Echo)
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if !ok {
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log.Fatalf("unexpected reply body type %T", replyMessage.Body)
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}
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if echo.ID != 921 || echo.Seq != 438 || string(echo.Data) != "WireGuard" {
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log.Fatalf("incorrect echo response: %#v", echo)
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}
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keepalivePacket := make([]byte, 16)
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keepalivePacket[0] = 4 // Type: Data
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keepalivePacket[1] = 0 // Reserved
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keepalivePacket[2] = 0 // Reserved
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keepalivePacket[3] = 0 // Reserved
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binary.LittleEndian.PutUint32(keepalivePacket[4:], theirIndex) // Their index
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binary.LittleEndian.PutUint64(keepalivePacket[8:], 1) // Nonce
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keepalivePacket = sendCipher.Encrypt(keepalivePacket, nil, nil) // Empty data means keepalive
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if _, err := conn.Write(keepalivePacket); err != nil {
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log.Fatalf("error writing keepalive message: %s", err)
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}
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}
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