package plugin
import (
"context"
"crypto/tls"
"errors"
"fmt"
"log"
"net"
"sync"
"sync/atomic"
"time"
"github.com/hashicorp/go-plugin/internal/plugin"
"github.com/oklog/run"
"google.golang.org/grpc"
"google.golang.org/grpc/credentials"
)
// streamer interface is used in the broker to send/receive connection
// information.
type streamer interface {
Send(*plugin.ConnInfo) error
Recv() (*plugin.ConnInfo, error)
Close()
}
// sendErr is used to pass errors back during a send.
type sendErr struct {
i *plugin.ConnInfo
ch chan error
}
// gRPCBrokerServer is used by the plugin to start a stream and to send
// connection information to/from the plugin. Implements GRPCBrokerServer and
// streamer interfaces.
type gRPCBrokerServer struct {
// send is used to send connection info to the gRPC stream.
send chan *sendErr
// recv is used to receive connection info from the gRPC stream.
recv chan *plugin.ConnInfo
// quit closes down the stream.
quit chan struct{}
// o is used to ensure we close the quit channel only once.
o sync.Once
}
func newGRPCBrokerServer() *gRPCBrokerServer {
return &gRPCBrokerServer{
send: make(chan *sendErr),
recv: make(chan *plugin.ConnInfo),
quit: make(chan struct{}),
}
}
// StartStream implements the GRPCBrokerServer interface and will block until
// the quit channel is closed or the context reports Done. The stream will pass
// connection information to/from the client.
func (s *gRPCBrokerServer) StartStream(stream plugin.GRPCBroker_StartStreamServer) error {
doneCh := stream.Context().Done()
defer s.Close()
// Proccess send stream
go func() {
for {
select {
case <-doneCh:
return
case <-s.quit:
return
case se := <-s.send:
err := stream.Send(se.i)
se.ch <- err
}
}
}()
// Process receive stream
for {
i, err := stream.Recv()
if err != nil {
return err
}
select {
case <-doneCh:
return nil
case <-s.quit:
return nil
case s.recv <- i:
}
}
return nil
}
// Send is used by the GRPCBroker to pass connection information into the stream
// to the client.
func (s *gRPCBrokerServer) Send(i *plugin.ConnInfo) error {
ch := make(chan error)
defer close(ch)
select {
case <-s.quit:
return errors.New("broker closed")
case s.send <- &sendErr{
i: i,
ch: ch,
}:
}
return <-ch
}
// Recv is used by the GRPCBroker to pass connection information that has been
// sent from the client from the stream to the broker.
func (s *gRPCBrokerServer) Recv() (*plugin.ConnInfo, error) {
select {
case <-s.quit:
return nil, errors.New("broker closed")
case i := <-s.recv:
return i, nil
}
}
// Close closes the quit channel, shutting down the stream.
func (s *gRPCBrokerServer) Close() {
s.o.Do(func() {
close(s.quit)
})
}
// gRPCBrokerClientImpl is used by the client to start a stream and to send
// connection information to/from the client. Implements GRPCBrokerClient and
// streamer interfaces.
type gRPCBrokerClientImpl struct {
// client is the underlying GRPC client used to make calls to the server.
client plugin.GRPCBrokerClient
// send is used to send connection info to the gRPC stream.
send chan *sendErr
// recv is used to receive connection info from the gRPC stream.
recv chan *plugin.ConnInfo
// quit closes down the stream.
quit chan struct{}
// o is used to ensure we close the quit channel only once.
o sync.Once
}
func newGRPCBrokerClient(conn *grpc.ClientConn) *gRPCBrokerClientImpl {
return &gRPCBrokerClientImpl{
client: plugin.NewGRPCBrokerClient(conn),
send: make(chan *sendErr),
recv: make(chan *plugin.ConnInfo),
quit: make(chan struct{}),
}
}
// StartStream implements the GRPCBrokerClient interface and will block until
// the quit channel is closed or the context reports Done. The stream will pass
// connection information to/from the plugin.
func (s *gRPCBrokerClientImpl) StartStream() error {
ctx, cancelFunc := context.WithCancel(context.Background())
defer cancelFunc()
defer s.Close()
stream, err := s.client.StartStream(ctx)
if err != nil {
return err
}
doneCh := stream.Context().Done()
go func() {
for {
select {
case <-doneCh:
return
case <-s.quit:
return
case se := <-s.send:
err := stream.Send(se.i)
se.ch <- err
}
}
}()
for {
i, err := stream.Recv()
if err != nil {
return err
}
select {
case <-doneCh:
return nil
case <-s.quit:
return nil
case s.recv <- i:
}
}
return nil
}
// Send is used by the GRPCBroker to pass connection information into the stream
// to the plugin.
func (s *gRPCBrokerClientImpl) Send(i *plugin.ConnInfo) error {
ch := make(chan error)
defer close(ch)
select {
case <-s.quit:
return errors.New("broker closed")
case s.send <- &sendErr{
i: i,
ch: ch,
}:
}
return <-ch
}
// Recv is used by the GRPCBroker to pass connection information that has been
// sent from the plugin to the broker.
func (s *gRPCBrokerClientImpl) Recv() (*plugin.ConnInfo, error) {
select {
case <-s.quit:
return nil, errors.New("broker closed")
case i := <-s.recv:
return i, nil
}
}
// Close closes the quit channel, shutting down the stream.
func (s *gRPCBrokerClientImpl) Close() {
s.o.Do(func() {
close(s.quit)
})
}
// GRPCBroker is responsible for brokering connections by unique ID.
//
// It is used by plugins to create multiple gRPC connections and data
// streams between the plugin process and the host process.
//
// This allows a plugin to request a channel with a specific ID to connect to
// or accept a connection from, and the broker handles the details of
// holding these channels open while they're being negotiated.
//
// The Plugin interface has access to these for both Server and Client.
// The broker can be used by either (optionally) to reserve and connect to
// new streams. This is useful for complex args and return values,
// or anything else you might need a data stream for.
type GRPCBroker struct {
nextId uint32
streamer streamer
streams map[uint32]*gRPCBrokerPending
tls *tls.Config
doneCh chan struct{}
o sync.Once
sync.Mutex
}
type gRPCBrokerPending struct {
ch chan *plugin.ConnInfo
doneCh chan struct{}
}
func newGRPCBroker(s streamer, tls *tls.Config) *GRPCBroker {
return &GRPCBroker{
streamer: s,
streams: make(map[uint32]*gRPCBrokerPending),
tls: tls,
doneCh: make(chan struct{}),
}
}
// Accept accepts a connection by ID.
//
// This should not be called multiple times with the same ID at one time.
func (b *GRPCBroker) Accept(id uint32) (net.Listener, error) {
listener, err := serverListener()
if err != nil {
return nil, err
}
err = b.streamer.Send(&plugin.ConnInfo{
ServiceId: id,
Network: listener.Addr().Network(),
Address: listener.Addr().String(),
})
if err != nil {
return nil, err
}
return listener, nil
}
// AcceptAndServe is used to accept a specific stream ID and immediately
// serve a gRPC server on that stream ID. This is used to easily serve
// complex arguments. Each AcceptAndServe call opens a new listener socket and
// sends the connection info down the stream to the dialer. Since a new
// connection is opened every call, these calls should be used sparingly.
// Multiple gRPC server implementations can be registered to a single
// AcceptAndServe call.
func (b *GRPCBroker) AcceptAndServe(id uint32, s func([]grpc.ServerOption) *grpc.Server) {
listener, err := b.Accept(id)
if err != nil {
log.Printf("[ERR] plugin: plugin acceptAndServe error: %s", err)
return
}
defer listener.Close()
var opts []grpc.ServerOption
if b.tls != nil {
opts = []grpc.ServerOption{grpc.Creds(credentials.NewTLS(b.tls))}
}
server := s(opts)
// Here we use a run group to close this goroutine if the server is shutdown
// or the broker is shutdown.
var g run.Group
{
// Serve on the listener, if shutting down call GracefulStop.
g.Add(func() error {
return server.Serve(listener)
}, func(err error) {
server.GracefulStop()
})
}
{
// block on the closeCh or the doneCh. If we are shutting down close the
// closeCh.
closeCh := make(chan struct{})
g.Add(func() error {
select {
case <-b.doneCh:
case <-closeCh:
}
return nil
}, func(err error) {
close(closeCh)
})
}
// Block until we are done
g.Run()
}
// Close closes the stream and all servers.
func (b *GRPCBroker) Close() error {
b.streamer.Close()
b.o.Do(func() {
close(b.doneCh)
})
return nil
}
// Dial opens a connection by ID.
func (b *GRPCBroker) Dial(id uint32) (conn *grpc.ClientConn, err error) {
var c *plugin.ConnInfo
// Open the stream
p := b.getStream(id)
select {
case c = <-p.ch:
close(p.doneCh)
case <-time.After(5 * time.Second):
return nil, fmt.Errorf("timeout waiting for connection info")
}
var addr net.Addr
switch c.Network {
case "tcp":
addr, err = net.ResolveTCPAddr("tcp", c.Address)
case "unix":
addr, err = net.ResolveUnixAddr("unix", c.Address)
default:
err = fmt.Errorf("Unknown address type: %s", c.Address)
}
if err != nil {
return nil, err
}
return dialGRPCConn(b.tls, netAddrDialer(addr))
}
// NextId returns a unique ID to use next.
//
// It is possible for very long-running plugin hosts to wrap this value,
// though it would require a very large amount of calls. In practice
// we've never seen it happen.
func (m *GRPCBroker) NextId() uint32 {
return atomic.AddUint32(&m.nextId, 1)
}
// Run starts the brokering and should be executed in a goroutine, since it
// blocks forever, or until the session closes.
//
// Uses of GRPCBroker never need to call this. It is called internally by
// the plugin host/client.
func (m *GRPCBroker) Run() {
for {
stream, err := m.streamer.Recv()
if err != nil {
// Once we receive an error, just exit
break
}
// Initialize the waiter
p := m.getStream(stream.ServiceId)
select {
case p.ch <- stream:
default:
}
go m.timeoutWait(stream.ServiceId, p)
}
}
func (m *GRPCBroker) getStream(id uint32) *gRPCBrokerPending {
m.Lock()
defer m.Unlock()
p, ok := m.streams[id]
if ok {
return p
}
m.streams[id] = &gRPCBrokerPending{
ch: make(chan *plugin.ConnInfo, 1),
doneCh: make(chan struct{}),
}
return m.streams[id]
}
func (m *GRPCBroker) timeoutWait(id uint32, p *gRPCBrokerPending) {
// Wait for the stream to either be picked up and connected, or
// for a timeout.
select {
case <-p.doneCh:
case <-time.After(5 * time.Second):
}
m.Lock()
defer m.Unlock()
// Delete the stream so no one else can grab it
delete(m.streams, id)
}
