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channel.go
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channel.go
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package directchannel
import (
"context"
"encoding/binary"
"fmt"
"io"
"math"
"strings"
"sync"
"time"
p2pcore "github.com/libp2p/go-libp2p-core"
"github.com/libp2p/go-libp2p-core/host"
"github.com/libp2p/go-libp2p-core/network"
"github.com/libp2p/go-libp2p-core/protocol"
"go.uber.org/zap"
"berty.tech/go-orbit-db/events"
"berty.tech/go-orbit-db/iface"
"berty.tech/go-orbit-db/pubsub"
)
const PROTOCOL = "/go-orbit-db/ipfs-direct-channel/1.0.0"
// Channel Channel is a pubsub used for a direct communication between peers
// new messages are received via events
type channel struct {
events.EventEmitter
receiverID p2pcore.PeerID
logger *zap.Logger
holder *channelHolder
stream io.Writer
muStream sync.Mutex
}
func (c *channel) Send(ctx context.Context, bytes []byte) error {
c.muStream.Lock()
stream := c.stream
c.muStream.Unlock()
if stream == nil {
return fmt.Errorf("stream is not opened")
}
if len(bytes) > math.MaxUint16 {
return fmt.Errorf("payload is too large")
}
b := make([]byte, 2)
binary.LittleEndian.PutUint16(b, uint16(len(bytes)))
if _, err := stream.Write(b); err != nil {
return err
}
_, err := stream.Write(bytes)
return err
}
func (c *channel) Close() error {
c.muStream.Lock()
c.stream = nil
c.muStream.Unlock()
return nil
}
func (c *channel) Connect(ctx context.Context) error {
var (
err error
stream network.Stream
id protocol.ID
)
if strings.Compare(c.holder.host.ID().String(), c.receiverID.String()) < 0 {
ctx, cancel := context.WithTimeout(ctx, time.Second*5)
id = c.holder.hostProtocolID(c.receiverID)
c.holder.muExpected.Lock()
streamChan := c.holder.expectedPID[id]
c.holder.muExpected.Unlock()
select {
case stream = <-streamChan:
// nothing else to do, stream is acquired
case <-ctx.Done():
cancel()
return fmt.Errorf("unable to create stream, err: %w", ctx.Err())
}
cancel()
} else {
id = c.holder.hostProtocolID(c.holder.host.ID())
stream, err = c.holder.host.NewStream(ctx, c.receiverID, id)
if err != nil {
return err
}
}
c.muStream.Lock()
c.stream = stream
c.muStream.Unlock()
go func() {
for {
if err := c.incomingEvent(ctx, stream); err == io.EOF {
return
} else if err != nil {
c.logger.Error("error while receiving event", zap.Error(err))
return
}
}
}()
return nil
}
func (c *channel) incomingEvent(ctx context.Context, stream network.Stream) error {
b := make([]byte, 2)
if _, err := stream.Read(b); err != nil {
if err == io.EOF {
return err
}
c.logger.Error("unable to read", zap.Error(err))
return err
}
data := make([]byte, binary.LittleEndian.Uint16(b))
_, err := stream.Read(data)
if err != nil {
if err == io.EOF {
return err
}
c.logger.Error("unable to read", zap.Error(err))
return err
}
c.Emit(ctx, pubsub.NewEventPayload(data))
return nil
}
type channelHolder struct {
expectedPID map[protocol.ID]chan network.Stream
host host.Host
muExpected sync.Mutex
}
func (h *channelHolder) NewChannel(ctx context.Context, receiver p2pcore.PeerID, opts *iface.DirectChannelOptions) (iface.DirectChannel, error) {
if opts == nil {
opts = &iface.DirectChannelOptions{}
}
if opts.Logger == nil {
opts.Logger = zap.NewNop()
}
ch := &channel{
receiverID: receiver,
logger: opts.Logger,
holder: h,
}
if strings.Compare(h.host.ID().String(), receiver.String()) < 0 {
id := h.hostProtocolID(receiver)
h.muExpected.Lock()
h.expectedPID[id] = make(chan network.Stream)
h.muExpected.Unlock()
go func() {
<-ctx.Done()
h.muExpected.Lock()
delete(h.expectedPID, id)
h.muExpected.Unlock()
}()
}
return ch, nil
}
func (h *channelHolder) hostProtocolID(receiver p2pcore.PeerID) protocol.ID {
return protocol.ID(fmt.Sprintf("%s/%s", PROTOCOL, receiver.String()))
}
func (h *channelHolder) checkExpectedStream(s string) bool {
h.muExpected.Lock()
_, ok := h.expectedPID[protocol.ID(s)]
h.muExpected.Unlock()
return ok
}
func (h *channelHolder) incomingConnHandler(stream network.Stream) {
h.muExpected.Lock()
ch, ok := h.expectedPID[stream.Protocol()]
if !ok {
return
}
h.muExpected.Unlock()
ch <- stream
}
func InitDirectChannelFactory(host host.Host) iface.DirectChannelFactory {
holder := &channelHolder{
expectedPID: map[protocol.ID]chan network.Stream{},
host: host,
}
host.SetStreamHandlerMatch(PROTOCOL, holder.checkExpectedStream, holder.incomingConnHandler)
return holder.NewChannel
}