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relay.go
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relay.go
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package relay
import (
"context"
"fmt"
"io"
"sync"
"sync/atomic"
"time"
"github.com/libp2p/go-libp2p/core/host"
"github.com/libp2p/go-libp2p/core/network"
"github.com/libp2p/go-libp2p/core/peer"
pb "github.com/libp2p/go-libp2p/p2p/protocol/circuitv1/pb"
"github.com/libp2p/go-libp2p/p2p/protocol/circuitv2/util"
logging "github.com/ipfs/go-log/v2"
pool "github.com/libp2p/go-buffer-pool"
ma "github.com/multiformats/go-multiaddr"
)
var log = logging.Logger("relay")
const (
ProtoID = "/libp2p/circuit/relay/0.1.0"
ServiceName = "libp2p.relay/v1"
StreamTimeout = time.Minute
ConnectTimeout = 30 * time.Second
HandshakeTimeout = time.Minute
relayHopTag = "relay-v1-hop"
relayHopTagValue = 2
maxMessageSize = 4096
)
type Relay struct {
closed int32
ctx context.Context
cancel context.CancelFunc
host host.Host
rc Resources
acl ACLFilter
scope network.ResourceScopeSpan
mx sync.Mutex
conns map[peer.ID]int
active int
}
func NewRelay(h host.Host, opts ...Option) (*Relay, error) {
r := &Relay{
host: h,
rc: DefaultResources(),
conns: make(map[peer.ID]int),
}
r.ctx, r.cancel = context.WithCancel(context.Background())
for _, opt := range opts {
err := opt(r)
if err != nil {
return nil, fmt.Errorf("error applying relay option: %w", err)
}
}
// get a scope for memory reservations at service level
err := h.Network().ResourceManager().ViewService(ServiceName,
func(s network.ServiceScope) error {
var err error
r.scope, err = s.BeginSpan()
return err
})
if err != nil {
return nil, err
}
h.SetStreamHandler(ProtoID, r.handleStream)
return r, nil
}
func (r *Relay) Close() error {
if atomic.CompareAndSwapInt32(&r.closed, 0, 1) {
r.host.RemoveStreamHandler(ProtoID)
r.scope.Done()
r.cancel()
}
return nil
}
func (r *Relay) handleStream(s network.Stream) {
log.Debugf("new relay stream from: %s", s.Conn().RemotePeer())
if err := s.Scope().SetService(ServiceName); err != nil {
log.Debugf("error attaching stream to relay service: %s", err)
s.Reset()
return
}
if err := s.Scope().ReserveMemory(maxMessageSize, network.ReservationPriorityAlways); err != nil {
log.Debugf("error reserving memory for stream: %s", err)
s.Reset()
return
}
defer s.Scope().ReleaseMemory(maxMessageSize)
rd := util.NewDelimitedReader(s, maxMessageSize)
defer rd.Close()
s.SetReadDeadline(time.Now().Add(StreamTimeout))
var msg pb.CircuitRelay
err := rd.ReadMsg(&msg)
if err != nil {
r.handleError(s, pb.CircuitRelay_MALFORMED_MESSAGE)
return
}
s.SetReadDeadline(time.Time{})
switch msg.GetType() {
case pb.CircuitRelay_HOP:
r.handleHopStream(s, &msg)
case pb.CircuitRelay_CAN_HOP:
r.handleCanHop(s, &msg)
case pb.CircuitRelay_STOP:
r.handleError(s, pb.CircuitRelay_STOP_RELAY_REFUSED)
default:
log.Warnf("unexpected relay handshake: %d", msg.GetType())
r.handleError(s, pb.CircuitRelay_MALFORMED_MESSAGE)
}
}
func (r *Relay) handleHopStream(s network.Stream, msg *pb.CircuitRelay) {
span, err := r.scope.BeginSpan()
if err != nil {
log.Debugf("failed to begin relay transaction: %s", err)
r.handleError(s, pb.CircuitRelay_HOP_CANT_SPEAK_RELAY)
return
}
fail := func(code pb.CircuitRelay_Status) {
span.Done()
r.handleError(s, code)
}
// reserve buffers for the relay
if err := span.ReserveMemory(2*r.rc.BufferSize, network.ReservationPriorityHigh); err != nil {
log.Debugf("error reserving memory for relay: %s", err)
fail(pb.CircuitRelay_HOP_CANT_SPEAK_RELAY)
return
}
src, err := peerToPeerInfo(msg.GetSrcPeer())
if err != nil {
fail(pb.CircuitRelay_HOP_SRC_MULTIADDR_INVALID)
return
}
if src.ID != s.Conn().RemotePeer() {
fail(pb.CircuitRelay_HOP_SRC_MULTIADDR_INVALID)
return
}
dest, err := peerToPeerInfo(msg.GetDstPeer())
if err != nil {
fail(pb.CircuitRelay_HOP_DST_MULTIADDR_INVALID)
return
}
if dest.ID == r.host.ID() {
fail(pb.CircuitRelay_HOP_CANT_RELAY_TO_SELF)
return
}
if r.acl != nil && !r.acl.AllowHop(src.ID, dest.ID) {
log.Debugf("refusing hop from %s to %s; ACL refused", src.ID, dest.ID)
fail(pb.CircuitRelay_HOP_CANT_SPEAK_RELAY)
return
}
r.mx.Lock()
if r.active >= r.rc.MaxCircuits {
r.mx.Unlock()
log.Debugf("refusing connection from %s to %s; too many active circuits", src.ID, dest.ID)
fail(pb.CircuitRelay_HOP_CANT_SPEAK_RELAY)
return
}
srcConns := r.conns[src.ID]
if srcConns >= r.rc.MaxCircuitsPerPeer {
r.mx.Unlock()
log.Debugf("refusing connection from %s to %s; too many connections from %s", src.ID, dest.ID, src)
fail(pb.CircuitRelay_HOP_CANT_SPEAK_RELAY)
return
}
destConns := r.conns[dest.ID]
if destConns >= r.rc.MaxCircuitsPerPeer {
r.mx.Unlock()
log.Debugf("refusing connection from %s to %s; too many connecitons to %s", src.ID, dest.ID, dest.ID)
fail(pb.CircuitRelay_HOP_CANT_SPEAK_RELAY)
return
}
r.active++
r.addConn(src.ID)
r.addConn(src.ID)
r.mx.Unlock()
cleanup := func() {
span.Done()
r.mx.Lock()
r.active--
r.rmConn(src.ID)
r.rmConn(dest.ID)
r.mx.Unlock()
}
// open stream
ctx, cancel := context.WithTimeout(r.ctx, ConnectTimeout)
defer cancel()
ctx = network.WithNoDial(ctx, "relay hop")
bs, err := r.host.NewStream(ctx, dest.ID, ProtoID)
if err != nil {
log.Debugf("error opening relay stream to %s: %s", dest.ID.Pretty(), err.Error())
if err == network.ErrNoConn {
r.handleError(s, pb.CircuitRelay_HOP_NO_CONN_TO_DST)
} else {
r.handleError(s, pb.CircuitRelay_HOP_CANT_DIAL_DST)
}
cleanup()
return
}
fail = func(code pb.CircuitRelay_Status) {
bs.Reset()
cleanup()
r.handleError(s, code)
}
if err := bs.Scope().SetService(ServiceName); err != nil {
log.Debugf("error attaching stream to relay service: %s", err)
fail(pb.CircuitRelay_HOP_CANT_SPEAK_RELAY)
return
}
// stop handshake
if err := bs.Scope().ReserveMemory(maxMessageSize, network.ReservationPriorityAlways); err != nil {
log.Debugf("failed to reserve memory for stream: %s", err)
fail(pb.CircuitRelay_HOP_CANT_SPEAK_RELAY)
return
}
defer bs.Scope().ReleaseMemory(maxMessageSize)
rd := util.NewDelimitedReader(bs, maxMessageSize)
wr := util.NewDelimitedWriter(bs)
defer rd.Close()
// set handshake deadline
bs.SetDeadline(time.Now().Add(HandshakeTimeout))
msg.Type = pb.CircuitRelay_STOP.Enum()
err = wr.WriteMsg(msg)
if err != nil {
log.Debugf("error writing stop handshake: %s", err.Error())
fail(pb.CircuitRelay_HOP_CANT_OPEN_DST_STREAM)
return
}
msg.Reset()
err = rd.ReadMsg(msg)
if err != nil {
log.Debugf("error reading stop response: %s", err.Error())
fail(pb.CircuitRelay_HOP_CANT_OPEN_DST_STREAM)
return
}
if msg.GetType() != pb.CircuitRelay_STATUS {
log.Debugf("unexpected relay stop response: not a status message (%d)", msg.GetType())
fail(pb.CircuitRelay_HOP_CANT_OPEN_DST_STREAM)
return
}
if msg.GetCode() != pb.CircuitRelay_SUCCESS {
log.Debugf("relay stop failure: %d", msg.GetCode())
fail(msg.GetCode())
return
}
err = r.writeResponse(s, pb.CircuitRelay_SUCCESS)
if err != nil {
log.Debugf("error writing relay response: %s", err.Error())
bs.Reset()
s.Reset()
cleanup()
return
}
// relay connection
log.Infof("relaying connection between %s and %s", src.ID.Pretty(), dest.ID.Pretty())
// reset deadline
bs.SetDeadline(time.Time{})
goroutines := new(int32)
*goroutines = 2
done := func() {
if atomic.AddInt32(goroutines, -1) == 0 {
s.Close()
bs.Close()
cleanup()
}
}
go r.relayConn(s, bs, src.ID, dest.ID, done)
go r.relayConn(bs, s, dest.ID, src.ID, done)
}
func (r *Relay) addConn(p peer.ID) {
conns := r.conns[p]
conns++
r.conns[p] = conns
if conns == 1 {
r.host.ConnManager().TagPeer(p, relayHopTag, relayHopTagValue)
}
}
func (r *Relay) rmConn(p peer.ID) {
conns := r.conns[p]
conns--
if conns > 0 {
r.conns[p] = conns
} else {
delete(r.conns, p)
r.host.ConnManager().UntagPeer(p, relayHopTag)
}
}
func (r *Relay) relayConn(src, dest network.Stream, srcID, destID peer.ID, done func()) {
defer done()
buf := pool.Get(r.rc.BufferSize)
defer pool.Put(buf)
count, err := io.CopyBuffer(dest, src, buf)
if err != nil {
log.Debugf("relay copy error: %s", err)
// Reset both.
src.Reset()
dest.Reset()
} else {
// propagate the close
dest.CloseWrite()
}
log.Debugf("relayed %d bytes from %s to %s", count, srcID, destID)
}
func (r *Relay) handleCanHop(s network.Stream, msg *pb.CircuitRelay) {
err := r.writeResponse(s, pb.CircuitRelay_SUCCESS)
if err != nil {
s.Reset()
log.Debugf("error writing relay response: %s", err.Error())
} else {
s.Close()
}
}
func (r *Relay) handleError(s network.Stream, code pb.CircuitRelay_Status) {
log.Warnf("relay error: %s", code)
err := r.writeResponse(s, code)
if err != nil {
s.Reset()
log.Debugf("error writing relay response: %s", err.Error())
} else {
s.Close()
}
}
// Queries a peer for support of hop relay
func CanHop(ctx context.Context, host host.Host, id peer.ID) (bool, error) {
s, err := host.NewStream(ctx, id, ProtoID)
if err != nil {
return false, err
}
defer s.Close()
rd := util.NewDelimitedReader(s, maxMessageSize)
wr := util.NewDelimitedWriter(s)
defer rd.Close()
var msg pb.CircuitRelay
msg.Type = pb.CircuitRelay_CAN_HOP.Enum()
if err := wr.WriteMsg(&msg); err != nil {
s.Reset()
return false, err
}
msg.Reset()
if err := rd.ReadMsg(&msg); err != nil {
s.Reset()
return false, err
}
if msg.GetType() != pb.CircuitRelay_STATUS {
return false, fmt.Errorf("unexpected relay response; not a status message (%d)", msg.GetType())
}
return msg.GetCode() == pb.CircuitRelay_SUCCESS, nil
}
func (r *Relay) writeResponse(s network.Stream, code pb.CircuitRelay_Status) error {
wr := util.NewDelimitedWriter(s)
var msg pb.CircuitRelay
msg.Type = pb.CircuitRelay_STATUS.Enum()
msg.Code = code.Enum()
return wr.WriteMsg(&msg)
}
func peerToPeerInfo(p *pb.CircuitRelay_Peer) (peer.AddrInfo, error) {
if p == nil {
return peer.AddrInfo{}, fmt.Errorf("nil peer")
}
id, err := peer.IDFromBytes(p.Id)
if err != nil {
return peer.AddrInfo{}, err
}
addrs := make([]ma.Multiaddr, 0, len(p.Addrs))
for _, addrBytes := range p.Addrs {
a, err := ma.NewMultiaddrBytes(addrBytes)
if err == nil {
addrs = append(addrs, a)
}
}
return peer.AddrInfo{ID: id, Addrs: addrs}, nil
}