lib/protocol: Understand older/newer Hello messages (fixes #3287)

This is in preparation for future changes, but also improves the
handling when talking to pre-v0.13 clients. It breaks out the Hello
message and magic from the rest of the protocol implementation, with the
intention that this small part of the protocol will survive future
changes.

To enable this, and future testing, the new ExchangeHello function takes
an interface that can be implemented by future Hello versions and
returns a version indendent result type. It correctly detects pre-v0.13
protocols and returns a "too old" error message which gets logged to the
user at warning level:

   [I6KAH] 09:21:36 WARNING: Connecting to [...]:
     the remote device speaks an older version of the protocol (v0.12) not
     compatible with this version

Conversely, something entirely unknown will generate:

   [I6KAH] 09:40:27 WARNING: Connecting to [...]:
     the remote device speaks an unknown (newer?) version of the protocol

The intention is that in future iterations the Hello exchange will
succeed on at least one side and ExchangeHello will return the actual
data from the Hello together with ErrTooOld and an even more precise
message can be generated.

GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/3289

11 files changed, 387 insertions, 156 deletions

diff --git a/lib/connections/service.go b/lib/connections/service.go
index 52b4136a9..39fa4b803 100644
--- a/lib/connections/service.go
+++ b/lib/connections/service.go
@@ -8,7 +8,6 @@ package connections
 
 import (
 	"crypto/tls"
-	"encoding/binary"
 	"errors"
 	"fmt"
 	"io"
@@ -153,12 +152,21 @@ next:
 			continue
 		}
 
-		hello, err := exchangeHello(c, s.model.GetHello(remoteID))
+		c.SetDeadline(time.Now().Add(20 * time.Second))
+		hello, err := protocol.ExchangeHello(c, s.model.GetHello(remoteID))
 		if err != nil {
-			l.Infof("Failed to exchange Hello messages with %s (%s): %s", remoteID, c.RemoteAddr(), err)
+			if protocol.IsVersionMismatch(err) {
+				// The error will be a relatively user friendly description
+				// of what's wrong with the version compatibility
+				l.Warnf("Connecting to %s (%s): %s", remoteID, c.RemoteAddr(), err)
+			} else {
+				// It's something else - connection reset or whatever
+				l.Infof("Failed to exchange Hello messages with %s (%s): %s", remoteID, c.RemoteAddr(), err)
+			}
 			c.Close()
 			continue
 		}
+		c.SetDeadline(time.Time{})
 
 		s.model.OnHello(remoteID, c.RemoteAddr(), hello)
 
@@ -553,54 +561,6 @@ func (s *Service) getListenerFactory(cfg config.Configuration, uri *url.URL) (li
 	return listenerFactory, nil
 }
 
-func exchangeHello(c net.Conn, h protocol.HelloMessage) (protocol.HelloMessage, error) {
-	if err := c.SetDeadline(time.Now().Add(20 * time.Second)); err != nil {
-		return protocol.HelloMessage{}, err
-	}
-	defer c.SetDeadline(time.Time{})
-
-	header := make([]byte, 8)
-	msg := h.MustMarshalXDR()
-
-	binary.BigEndian.PutUint32(header[:4], protocol.HelloMessageMagic)
-	binary.BigEndian.PutUint32(header[4:], uint32(len(msg)))
-
-	if _, err := c.Write(header); err != nil {
-		return protocol.HelloMessage{}, err
-	}
-
-	if _, err := c.Write(msg); err != nil {
-		return protocol.HelloMessage{}, err
-	}
-
-	if _, err := io.ReadFull(c, header); err != nil {
-		return protocol.HelloMessage{}, err
-	}
-
-	if binary.BigEndian.Uint32(header[:4]) != protocol.HelloMessageMagic {
-		return protocol.HelloMessage{}, fmt.Errorf("incorrect magic")
-	}
-
-	msgSize := binary.BigEndian.Uint32(header[4:])
-	if msgSize > 1024 {
-		return protocol.HelloMessage{}, fmt.Errorf("hello message too big")
-	}
-
-	buf := make([]byte, msgSize)
-
-	var hello protocol.HelloMessage
-
-	if _, err := io.ReadFull(c, buf); err != nil {
-		return protocol.HelloMessage{}, err
-	}
-
-	if err := hello.UnmarshalXDR(buf); err != nil {
-		return protocol.HelloMessage{}, err
-	}
-
-	return hello, nil
-}
-
 func filterAndFindSleepDuration(nextDial map[string]time.Time, seen []string, now time.Time) (map[string]time.Time, time.Duration) {
 	newNextDial := make(map[string]time.Time)
 
diff --git a/lib/connections/structs.go b/lib/connections/structs.go
index 33ce38020..da62bd72e 100644
--- a/lib/connections/structs.go
+++ b/lib/connections/structs.go
@@ -66,11 +66,11 @@ type genericListener interface {
 
 type Model interface {
 	protocol.Model
-	AddConnection(conn Connection, hello protocol.HelloMessage)
+	AddConnection(conn Connection, hello protocol.HelloResult)
 	ConnectedTo(remoteID protocol.DeviceID) bool
 	IsPaused(remoteID protocol.DeviceID) bool
-	OnHello(protocol.DeviceID, net.Addr, protocol.HelloMessage)
-	GetHello(protocol.DeviceID) protocol.HelloMessage
+	OnHello(protocol.DeviceID, net.Addr, protocol.HelloResult)
+	GetHello(protocol.DeviceID) protocol.Version13HelloMessage
 }
 
 // serviceFunc wraps a function to create a suture.Service without stop
diff --git a/lib/model/model.go b/lib/model/model.go
index e26fd0583..7e0ec2fe2 100644
--- a/lib/model/model.go
+++ b/lib/model/model.go
@@ -94,7 +94,7 @@ type Model struct {
 	fmut               sync.RWMutex                                           // protects the above
 
 	conn              map[protocol.DeviceID]connections.Connection
-	helloMessages     map[protocol.DeviceID]protocol.HelloMessage
+	helloMessages     map[protocol.DeviceID]protocol.HelloResult
 	deviceClusterConf map[protocol.DeviceID]protocol.ClusterConfigMessage
 	devicePaused      map[protocol.DeviceID]bool
 	deviceDownloads   map[protocol.DeviceID]*deviceDownloadState
@@ -139,7 +139,7 @@ func NewModel(cfg *config.Wrapper, id protocol.DeviceID, deviceName, clientName,
 		folderRunnerTokens: make(map[string][]suture.ServiceToken),
 		folderStatRefs:     make(map[string]*stats.FolderStatisticsReference),
 		conn:               make(map[protocol.DeviceID]connections.Connection),
-		helloMessages:      make(map[protocol.DeviceID]protocol.HelloMessage),
+		helloMessages:      make(map[protocol.DeviceID]protocol.HelloResult),
 		deviceClusterConf:  make(map[protocol.DeviceID]protocol.ClusterConfigMessage),
 		devicePaused:       make(map[protocol.DeviceID]bool),
 		deviceDownloads:    make(map[protocol.DeviceID]*deviceDownloadState),
@@ -983,7 +983,7 @@ func (m *Model) SetIgnores(folder string, content []string) error {
 // OnHello is called when an device connects to us.
 // This allows us to extract some information from the Hello message
 // and add it to a list of known devices ahead of any checks.
-func (m *Model) OnHello(remoteID protocol.DeviceID, addr net.Addr, hello protocol.HelloMessage) {
+func (m *Model) OnHello(remoteID protocol.DeviceID, addr net.Addr, hello protocol.HelloResult) {
 	for deviceID := range m.cfg.Devices() {
 		if deviceID == remoteID {
 			// Existing device, we will get the hello message in AddConnection
@@ -1003,8 +1003,8 @@ func (m *Model) OnHello(remoteID protocol.DeviceID, addr net.Addr, hello protoco
 }
 
 // GetHello is called when we are about to connect to some remote device.
-func (m *Model) GetHello(protocol.DeviceID) protocol.HelloMessage {
-	return protocol.HelloMessage{
+func (m *Model) GetHello(protocol.DeviceID) protocol.Version13HelloMessage {
+	return protocol.Version13HelloMessage{
 		DeviceName:    m.deviceName,
 		ClientName:    m.clientName,
 		ClientVersion: m.clientVersion,
@@ -1014,7 +1014,7 @@ func (m *Model) GetHello(protocol.DeviceID) protocol.HelloMessage {
 // AddConnection adds a new peer connection to the model. An initial index will
 // be sent to the connected peer, thereafter index updates whenever the local
 // folder changes.
-func (m *Model) AddConnection(conn connections.Connection, hello protocol.HelloMessage) {
+func (m *Model) AddConnection(conn connections.Connection, hello protocol.HelloResult) {
 	deviceID := conn.ID()
 
 	m.pmut.Lock()
diff --git a/lib/model/model_test.go b/lib/model/model_test.go
index 138fa3dfc..839209dd2 100644
--- a/lib/model/model_test.go
+++ b/lib/model/model_test.go
@@ -303,7 +303,7 @@ func BenchmarkRequest(b *testing.B) {
 			Priority: 10,
 		},
 		Connection: fc,
-	}, protocol.HelloMessage{})
+	}, protocol.HelloResult{})
 	m.Index(device1, "default", files, 0, nil)
 
 	b.ResetTimer()
@@ -319,7 +319,7 @@ func BenchmarkRequest(b *testing.B) {
 }
 
 func TestDeviceRename(t *testing.T) {
-	hello := protocol.HelloMessage{
+	hello := protocol.HelloResult{
 		ClientName:    "syncthing",
 		ClientVersion: "v0.9.4",
 	}
diff --git a/lib/protocol/hello.go b/lib/protocol/hello.go
new file mode 100644
index 000000000..b7b324b29
--- /dev/null
+++ b/lib/protocol/hello.go
@@ -0,0 +1,105 @@
+// Copyright (C) 2016 The Protocol Authors.
+
+package protocol
+
+import (
+	"encoding/binary"
+	"errors"
+	"fmt"
+	"io"
+)
+
+// The HelloMessage interface is implemented by the version specific hello
+// message. It knows its magic number and how to serialize itself to a byte
+// buffer.
+type HelloMessage interface {
+	Magic() uint32
+	Marshal() ([]byte, error)
+}
+
+// The HelloResult is the non version specific interpretation of the other
+// side's Hello message.
+type HelloResult struct {
+	DeviceName    string
+	ClientName    string
+	ClientVersion string
+}
+
+var (
+	// ErrTooOldVersion12 is returned by ExchangeHello when the other side
+	// speaks the older, incompatible version 0.12 of the protocol.
+	ErrTooOldVersion12 = errors.New("the remote device speaks an older version of the protocol (v0.12) not compatible with this version")
+	// ErrUnknownMagic is returned by ExchangeHellow when the other side
+	// speaks something entirely unknown.
+	ErrUnknownMagic = errors.New("the remote device speaks an unknown (newer?) version of the protocol")
+)
+
+func ExchangeHello(c io.ReadWriter, h HelloMessage) (HelloResult, error) {
+	if err := writeHello(c, h); err != nil {
+		return HelloResult{}, err
+	}
+	return readHello(c)
+}
+
+// IsVersionMismatch returns true if the error is a reliable indication of a
+// version mismatch that we might want to alert the user about.
+func IsVersionMismatch(err error) bool {
+	switch err {
+	case ErrTooOldVersion12, ErrUnknownMagic:
+		return true
+	default:
+		return false
+	}
+}
+
+func readHello(c io.Reader) (HelloResult, error) {
+	header := make([]byte, 8)
+	if _, err := io.ReadFull(c, header); err != nil {
+		return HelloResult{}, err
+	}
+
+	switch binary.BigEndian.Uint32(header[:4]) {
+	case Version13HelloMagic:
+		// This is a v0.13 Hello message in XDR format
+		msgSize := binary.BigEndian.Uint32(header[4:])
+		if msgSize > 1024 {
+			return HelloResult{}, fmt.Errorf("hello message too big")
+		}
+		buf := make([]byte, msgSize)
+		if _, err := io.ReadFull(c, buf); err != nil {
+			return HelloResult{}, err
+		}
+
+		var hello Version13HelloMessage
+		if err := hello.UnmarshalXDR(buf); err != nil {
+			return HelloResult{}, err
+		}
+		res := HelloResult{
+			DeviceName:    hello.DeviceName,
+			ClientName:    hello.ClientName,
+			ClientVersion: hello.ClientVersion,
+		}
+		return res, nil
+
+	case 0x00010001, 0x00010000:
+		// This is the first word of a v0.12 cluster config message.
+		// (Version 0, message ID 1, message type 0, compression enabled or disabled)
+		return HelloResult{}, ErrTooOldVersion12
+	}
+
+	return HelloResult{}, ErrUnknownMagic
+}
+
+func writeHello(c io.Writer, h HelloMessage) error {
+	msg, err := h.Marshal()
+	if err != nil {
+		return err
+	}
+
+	header := make([]byte, 8)
+	binary.BigEndian.PutUint32(header[:4], h.Magic())
+	binary.BigEndian.PutUint32(header[4:], uint32(len(msg)))
+
+	_, err = c.Write(append(header, msg...))
+	return err
+}
diff --git a/lib/protocol/hello_test.go b/lib/protocol/hello_test.go
new file mode 100644
index 000000000..01caad540
--- /dev/null
+++ b/lib/protocol/hello_test.go
@@ -0,0 +1,150 @@
+// Copyright (C) 2016 The Protocol Authors.
+
+package protocol
+
+import (
+	"bytes"
+	"encoding/binary"
+	"encoding/hex"
+	"io"
+	"regexp"
+	"testing"
+)
+
+var spaceRe = regexp.MustCompile(`\s`)
+
+func TestVersion13Hello(t *testing.T) {
+	// Tests that we can send and receive a version 0.13 hello message.
+
+	expected := Version13HelloMessage{
+		DeviceName:    "test device",
+		ClientName:    "syncthing",
+		ClientVersion: "v0.13.5",
+	}
+	msgBuf := expected.MustMarshalXDR()
+
+	hdrBuf := make([]byte, 8)
+	binary.BigEndian.PutUint32(hdrBuf, Version13HelloMagic)
+	binary.BigEndian.PutUint32(hdrBuf[4:], uint32(len(msgBuf)))
+
+	outBuf := new(bytes.Buffer)
+	outBuf.Write(hdrBuf)
+	outBuf.Write(msgBuf)
+
+	inBuf := new(bytes.Buffer)
+
+	conn := &readWriter{outBuf, inBuf}
+
+	send := Version13HelloMessage{
+		DeviceName:    "this device",
+		ClientName:    "other client",
+		ClientVersion: "v0.13.6",
+	}
+
+	res, err := ExchangeHello(conn, send)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if res.ClientName != expected.ClientName {
+		t.Errorf("incorrect ClientName %q != expected %q", res.ClientName, expected.ClientName)
+	}
+	if res.ClientVersion != expected.ClientVersion {
+		t.Errorf("incorrect ClientVersion %q != expected %q", res.ClientVersion, expected.ClientVersion)
+	}
+	if res.DeviceName != expected.DeviceName {
+		t.Errorf("incorrect DeviceName %q != expected %q", res.DeviceName, expected.DeviceName)
+	}
+}
+
+func TestVersion12Hello(t *testing.T) {
+	// Tests that we can correctly interpret the lack of a hello message
+	// from a v0.12 client.
+
+	// This is the typical v0.12 connection start - our message header for a
+	// ClusterConfig message and then the cluster config message data. Taken
+	// from a protocol dump of a recent v0.12 client.
+	msg, _ := hex.DecodeString(spaceRe.ReplaceAllString(`
+	00010001
+	0000014a
+	7802000070000000027332000100a00973796e637468696e670e00b000000876
+	302e31322e32352400b00000000764656661756c741e00f01603000000204794
+	03ffdef496b5f5e5bc9c0a15221e70073164509fa30761af63094f6f945c3800
+	2073312f00f20b0001000000157463703a2f2f3132372e302e302e313a323230
+	301f00012400080500003000001000f1122064516fb94d24e7b637d20d9846eb
+	aeffb09556ef3968c8276fefc3fe24c144c2640002c0000034000f640002021f
+	00004f00090400003000001100f11220dff67945f05bdab4270acd6057f1eacf
+	a3ac93cade07ce6a89384c181ad6b80e640010332b000fc80007021f00012400
+	080500046400041400f21f2dc2af5c5f28e38384295f2fc2af2052c3a46b736d
+	c3b67267c3a57320e58aa8e4bd9c20d090d0b4d180d0b5d18136001f026c01b8
+	90000000000000000000`, ``))
+
+	outBuf := new(bytes.Buffer)
+	outBuf.Write(msg)
+
+	inBuf := new(bytes.Buffer)
+
+	conn := &readWriter{outBuf, inBuf}
+
+	send := Version13HelloMessage{
+		DeviceName:    "this device",
+		ClientName:    "other client",
+		ClientVersion: "v0.13.6",
+	}
+
+	_, err := ExchangeHello(conn, send)
+	if err != ErrTooOldVersion12 {
+		t.Errorf("unexpected error %v != ErrTooOld", err)
+	}
+}
+
+func TestUnknownHello(t *testing.T) {
+	// Tests that we react correctly to a completely unknown magic number.
+
+	// This is an unknown magic follow byte some message data.
+	msg, _ := hex.DecodeString(spaceRe.ReplaceAllString(`
+	12345678
+	0000014a
+	7802000070000000027332000100a00973796e637468696e670e00b000000876
+	302e31322e32352400b00000000764656661756c741e00f01603000000204794
+	03ffdef496b5f5e5bc9c0a15221e70073164509fa30761af63094f6f945c3800
+	2073312f00f20b0001000000157463703a2f2f3132372e302e302e313a323230
+	301f00012400080500003000001000f1122064516fb94d24e7b637d20d9846eb
+	aeffb09556ef3968c8276fefc3fe24c144c2640002c0000034000f640002021f
+	00004f00090400003000001100f11220dff67945f05bdab4270acd6057f1eacf
+	a3ac93cade07ce6a89384c181ad6b80e640010332b000fc80007021f00012400
+	080500046400041400f21f2dc2af5c5f28e38384295f2fc2af2052c3a46b736d
+	c3b67267c3a57320e58aa8e4bd9c20d090d0b4d180d0b5d18136001f026c01b8
+	90000000000000000000`, ``))
+
+	outBuf := new(bytes.Buffer)
+	outBuf.Write(msg)
+
+	inBuf := new(bytes.Buffer)
+
+	conn := &readWriter{outBuf, inBuf}
+
+	send := Version13HelloMessage{
+		DeviceName:    "this device",
+		ClientName:    "other client",
+		ClientVersion: "v0.13.6",
+	}
+
+	_, err := ExchangeHello(conn, send)
+	if err != ErrUnknownMagic {
+		t.Errorf("unexpected error %v != ErrUnknownMagic", err)
+	}
+}
+
+type readWriter struct {
+	r io.Reader
+	w io.Writer
+}
+
+func (rw *readWriter) Write(data []byte) (int, error) {
+	return rw.w.Write(data)
+}
+
+func (rw *readWriter) Read(data []byte) (int, error) {
+	return rw.r.Read(data)
+}
diff --git a/lib/protocol/hello_v0.13.go b/lib/protocol/hello_v0.13.go
new file mode 100644
index 000000000..e56f1d93e
--- /dev/null
+++ b/lib/protocol/hello_v0.13.go
@@ -0,0 +1,24 @@
+// Copyright (C) 2016 The Protocol Authors.
+
+//go:generate -command genxdr go run ../../vendor/github.com/calmh/xdr/cmd/genxdr/main.go
+//go:generate genxdr -o hello_v0.13_xdr.go hello_v0.13.go
+
+package protocol
+
+var (
+	Version13HelloMagic uint32 = 0x9F79BC40
+)
+
+type Version13HelloMessage struct {
+	DeviceName    string // max:64
+	ClientName    string // max:64
+	ClientVersion string // max:64
+}
+
+func (m Version13HelloMessage) Magic() uint32 {
+	return Version13HelloMagic
+}
+
+func (m Version13HelloMessage) Marshal() ([]byte, error) {
+	return m.MarshalXDR()
+}
diff --git a/lib/protocol/hello_v0.13_xdr.go b/lib/protocol/hello_v0.13_xdr.go
new file mode 100644
index 000000000..ecf149671
--- /dev/null
+++ b/lib/protocol/hello_v0.13_xdr.go
@@ -0,0 +1,85 @@
+// ************************************************************
+// This file is automatically generated by genxdr. Do not edit.
+// ************************************************************
+
+package protocol
+
+import (
+	"github.com/calmh/xdr"
+)
+
+/*
+
+Version13HelloMessage Structure:
+
+ 0                   1                   2                   3
+ 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+/                                                               /
+\              Device Name (length + padded data)               \
+/                                                               /
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+/                                                               /
+\              Client Name (length + padded data)               \
+/                                                               /
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+/                                                               /
+\             Client Version (length + padded data)             \
+/                                                               /
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+
+struct Version13HelloMessage {
+	string DeviceName<64>;
+	string ClientName<64>;
+	string ClientVersion<64>;
+}
+
+*/
+
+func (o Version13HelloMessage) XDRSize() int {
+	return 4 + len(o.DeviceName) + xdr.Padding(len(o.DeviceName)) +
+		4 + len(o.ClientName) + xdr.Padding(len(o.ClientName)) +
+		4 + len(o.ClientVersion) + xdr.Padding(len(o.ClientVersion))
+}
+
+func (o Version13HelloMessage) MarshalXDR() ([]byte, error) {
+	buf := make([]byte, o.XDRSize())
+	m := &xdr.Marshaller{Data: buf}
+	return buf, o.MarshalXDRInto(m)
+}
+
+func (o Version13HelloMessage) MustMarshalXDR() []byte {
+	bs, err := o.MarshalXDR()
+	if err != nil {
+		panic(err)
+	}
+	return bs
+}
+
+func (o Version13HelloMessage) MarshalXDRInto(m *xdr.Marshaller) error {
+	if l := len(o.DeviceName); l > 64 {
+		return xdr.ElementSizeExceeded("DeviceName", l, 64)
+	}
+	m.MarshalString(o.DeviceName)
+	if l := len(o.ClientName); l > 64 {
+		return xdr.ElementSizeExceeded("ClientName", l, 64)
+	}
+	m.MarshalString(o.ClientName)
+	if l := len(o.ClientVersion); l > 64 {
+		return xdr.ElementSizeExceeded("ClientVersion", l, 64)
+	}
+	m.MarshalString(o.ClientVersion)
+	return m.Error
+}
+
+func (o *Version13HelloMessage) UnmarshalXDR(bs []byte) error {
+	u := &xdr.Unmarshaller{Data: bs}
+	return o.UnmarshalXDRFrom(u)
+}
+func (o *Version13HelloMessage) UnmarshalXDRFrom(u *xdr.Unmarshaller) error {
+	o.DeviceName = u.UnmarshalStringMax(64)
+	o.ClientName = u.UnmarshalStringMax(64)
+	o.ClientVersion = u.UnmarshalStringMax(64)
+	return u.Error
+}
diff --git a/lib/protocol/message.go b/lib/protocol/message.go
index 9e195661a..e4bed2d10 100644
--- a/lib/protocol/message.go
+++ b/lib/protocol/message.go
@@ -12,16 +12,9 @@ import (
 )
 
 var (
-	sha256OfEmptyBlock        = sha256.Sum256(make([]byte, BlockSize))
-	HelloMessageMagic  uint32 = 0x9F79BC40
+	sha256OfEmptyBlock = sha256.Sum256(make([]byte, BlockSize))
 )
 
-type HelloMessage struct {
-	DeviceName    string // max:64
-	ClientName    string // max:64
-	ClientVersion string // max:64
-}
-
 type IndexMessage struct {
 	Folder  string     // max:256
 	Files   []FileInfo // max:1000000
diff --git a/lib/protocol/message_xdr.go b/lib/protocol/message_xdr.go
index 206bd394b..32179642c 100644
--- a/lib/protocol/message_xdr.go
+++ b/lib/protocol/message_xdr.go
@@ -10,82 +10,6 @@ import (
 
 /*
 
-HelloMessage Structure:
-
- 0                   1                   2                   3
- 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-/                                                               /
-\              Device Name (length + padded data)               \
-/                                                               /
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-/                                                               /
-\              Client Name (length + padded data)               \
-/                                                               /
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-/                                                               /
-\             Client Version (length + padded data)             \
-/                                                               /
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-
-
-struct HelloMessage {
-	string DeviceName<64>;
-	string ClientName<64>;
-	string ClientVersion<64>;
-}
-
-*/
-
-func (o HelloMessage) XDRSize() int {
-	return 4 + len(o.DeviceName) + xdr.Padding(len(o.DeviceName)) +
-		4 + len(o.ClientName) + xdr.Padding(len(o.ClientName)) +
-		4 + len(o.ClientVersion) + xdr.Padding(len(o.ClientVersion))
-}
-
-func (o HelloMessage) MarshalXDR() ([]byte, error) {
-	buf := make([]byte, o.XDRSize())
-	m := &xdr.Marshaller{Data: buf}
-	return buf, o.MarshalXDRInto(m)
-}
-
-func (o HelloMessage) MustMarshalXDR() []byte {
-	bs, err := o.MarshalXDR()
-	if err != nil {
-		panic(err)
-	}
-	return bs
-}
-
-func (o HelloMessage) MarshalXDRInto(m *xdr.Marshaller) error {
-	if l := len(o.DeviceName); l > 64 {
-		return xdr.ElementSizeExceeded("DeviceName", l, 64)
-	}
-	m.MarshalString(o.DeviceName)
-	if l := len(o.ClientName); l > 64 {
-		return xdr.ElementSizeExceeded("ClientName", l, 64)
-	}
-	m.MarshalString(o.ClientName)
-	if l := len(o.ClientVersion); l > 64 {
-		return xdr.ElementSizeExceeded("ClientVersion", l, 64)
-	}
-	m.MarshalString(o.ClientVersion)
-	return m.Error
-}
-
-func (o *HelloMessage) UnmarshalXDR(bs []byte) error {
-	u := &xdr.Unmarshaller{Data: bs}
-	return o.UnmarshalXDRFrom(u)
-}
-func (o *HelloMessage) UnmarshalXDRFrom(u *xdr.Unmarshaller) error {
-	o.DeviceName = u.UnmarshalStringMax(64)
-	o.ClientName = u.UnmarshalStringMax(64)
-	o.ClientVersion = u.UnmarshalStringMax(64)
-	return u.Error
-}
-
-/*
-
 IndexMessage Structure:
 
  0                   1                   2                   3
diff --git a/lib/protocol/protocol_test.go b/lib/protocol/protocol_test.go
index 82cdd0757..2a6f51788 100644
--- a/lib/protocol/protocol_test.go
+++ b/lib/protocol/protocol_test.go
@@ -188,16 +188,6 @@ func TestClose(t *testing.T) {
 	}
 }
 
-func TestElementSizeExceededNested(t *testing.T) {
-	m := HelloMessage{
-		ClientName: "longstringlongstringlongstringinglongstringlongstringlonlongstringlongstringlon",
-	}
-	_, err := m.MarshalXDR()
-	if err == nil {
-		t.Errorf("ID length %d > max 64, but no error", len(m.ClientName))
-	}
-}
-
 func TestMarshalIndexMessage(t *testing.T) {
 	if testing.Short() {
 		quickCfg.MaxCount = 10