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remove support for the simultaneous open extension (#107)
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@marten-seemann
marten-seemann authored Sep 6, 2023
1 parent 2ce8b0a commit 8fabf3a
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Showing 2 changed files with 1 addition and 385 deletions.
213 changes: 0 additions & 213 deletions client.go
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Original file line number Diff line number Diff line change
Expand Up @@ -2,15 +2,11 @@ package multistream

import (
"bytes"
"crypto/rand"
"encoding/binary"
"errors"
"fmt"
"io"
"os"
"runtime/debug"
"strconv"
"strings"
)

// ErrNotSupported is the error returned when the muxer doesn't support
Expand All @@ -34,12 +30,6 @@ func (e ErrNotSupported[T]) Is(target error) bool {
// specified.
var ErrNoProtocols = errors.New("no protocols specified")

const (
tieBreakerPrefix = "select:"
initiator = "initiator"
responder = "responder"
)

// SelectProtoOrFail performs the initial multistream handshake
// to inform the muxer of the protocol that will be used to communicate
// on this ReadWriteCloser. It returns an error if, for example,
Expand Down Expand Up @@ -110,84 +100,6 @@ func SelectOneOf[T StringLike](protos []T, rwc io.ReadWriteCloser) (proto T, err
return proto, err
}

const simOpenProtocol = "/libp2p/simultaneous-connect"

// SelectWithSimopenOrFail performs protocol negotiation with the simultaneous open extension.
// The returned boolean indicator will be true if we should act as a server.
func SelectWithSimopenOrFail[T StringLike](protos []T, rwc io.ReadWriteCloser) (proto T, isServer bool, err error) {
defer func() {
if rerr := recover(); rerr != nil {
fmt.Fprintf(os.Stderr, "caught panic: %s\n%s\n", rerr, debug.Stack())
err = fmt.Errorf("panic selecting protocol with simopen: %s", rerr)
}
}()

if len(protos) == 0 {
return "", false, ErrNoProtocols
}

werrCh := make(chan error, 1)
go func() {
var buf bytes.Buffer
if err := delitmWriteAll(&buf, []byte(ProtocolID), []byte(simOpenProtocol), []byte(protos[0])); err != nil {
werrCh <- err
return
}

_, err := io.Copy(rwc, &buf)
werrCh <- err
}()

if err := readMultistreamHeader(rwc); err != nil {
return "", false, err
}

tok, err := ReadNextToken[T](rwc)
if err != nil {
return "", false, err
}

if err = <-werrCh; err != nil {
return "", false, err
}

switch tok {
case simOpenProtocol:
// simultaneous open
return simOpen(protos, rwc)
case "na":
// client open
proto, err := clientOpen(protos, rwc)
if err != nil {
return "", false, err
}
return proto, false, nil
default:
return "", false, fmt.Errorf("unexpected response: %s", tok)
}
}

func clientOpen[T StringLike](protos []T, rwc io.ReadWriteCloser) (T, error) {
// check to see if we selected the pipelined protocol
tok, err := ReadNextToken[T](rwc)
if err != nil {
return "", err
}

switch tok {
case protos[0]:
return tok, nil
case "na":
proto, err := selectProtosOrFail(protos[1:], rwc)
if _, ok := err.(ErrNotSupported[T]); ok {
return "", ErrNotSupported[T]{protos}
}
return proto, err
default:
return "", fmt.Errorf("unexpected response: %s", tok)
}
}

func selectProtosOrFail[T StringLike](protos []T, rwc io.ReadWriteCloser) (T, error) {
for _, p := range protos {
err := trySelect(p, rwc)
Expand All @@ -202,131 +114,6 @@ func selectProtosOrFail[T StringLike](protos []T, rwc io.ReadWriteCloser) (T, er
return "", ErrNotSupported[T]{protos}
}

func simOpen[T StringLike](protos []T, rwc io.ReadWriteCloser) (T, bool, error) {
randBytes := make([]byte, 8)
_, err := rand.Read(randBytes)
if err != nil {
return "", false, err
}
myNonce := binary.LittleEndian.Uint64(randBytes)

werrCh := make(chan error, 1)
go func() {
myselect := []byte(tieBreakerPrefix + strconv.FormatUint(myNonce, 10))
err := delimWriteBuffered(rwc, myselect)
werrCh <- err
}()

// skip exactly one protocol
// see https://github.com/multiformats/go-multistream/pull/42#discussion_r558757135
_, err = ReadNextToken[T](rwc)
if err != nil {
return "", false, err
}

// read the tie breaker nonce
tok, err := ReadNextToken[T](rwc)
if err != nil {
return "", false, err
}
if !strings.HasPrefix(string(tok), tieBreakerPrefix) {
return "", false, errors.New("tie breaker nonce not sent with the correct prefix")
}

if err = <-werrCh; err != nil {
return "", false, err
}

peerNonce, err := strconv.ParseUint(string(tok[len(tieBreakerPrefix):]), 10, 64)
if err != nil {
return "", false, err
}

var iamserver bool

if peerNonce == myNonce {
return "", false, errors.New("failed client selection; identical nonces")
}
iamserver = peerNonce > myNonce

var proto T
if iamserver {
proto, err = simOpenSelectServer(protos, rwc)
} else {
proto, err = simOpenSelectClient(protos, rwc)
}

return proto, iamserver, err
}

func simOpenSelectServer[T StringLike](protos []T, rwc io.ReadWriteCloser) (T, error) {
werrCh := make(chan error, 1)
go func() {
err := delimWriteBuffered(rwc, []byte(responder))
werrCh <- err
}()

tok, err := ReadNextToken[T](rwc)
if err != nil {
return "", err
}
if tok != initiator {
return "", fmt.Errorf("unexpected response: %s", tok)
}
if err = <-werrCh; err != nil {
return "", err
}
for {
tok, err = ReadNextToken[T](rwc)

if err == io.EOF {
return "", ErrNotSupported[T]{protos}
}

if err != nil {
return "", err
}

for _, p := range protos {
if tok == p {
err = delimWriteBuffered(rwc, []byte(p))
if err != nil {
return "", err
}

return p, nil
}
}

err = delimWriteBuffered(rwc, []byte("na"))
if err != nil {
return "", err
}
}

}

func simOpenSelectClient[T StringLike](protos []T, rwc io.ReadWriteCloser) (T, error) {
werrCh := make(chan error, 1)
go func() {
err := delimWriteBuffered(rwc, []byte(initiator))
werrCh <- err
}()

tok, err := ReadNextToken[T](rwc)
if err != nil {
return "", err
}
if tok != responder {
return "", fmt.Errorf("unexpected response: %s", tok)
}
if err = <-werrCh; err != nil {
return "", err
}

return selectProtosOrFail(protos, rwc)
}

func readMultistreamHeader(r io.Reader) error {
tok, err := ReadNextToken[string](r)
if err != nil {
Expand Down
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