forked from aws/session-manager-plugin
/
muxportforwarding.go
313 lines (271 loc) · 8.7 KB
/
muxportforwarding.go
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// Copyright 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License"). You may not
// use this file except in compliance with the License. A copy of the
// License is located at
//
// http://aws.amazon.com/apache2.0/
//
// or in the "license" file accompanying this file. This file is distributed
// on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
// either express or implied. See the License for the specific language governing
// permissions and limitations under the License.
// Package portsession starts port session.
package portsession
import (
"bytes"
"context"
"encoding/binary"
"fmt"
"hash/fnv"
"io"
"net"
"os"
"os/signal"
"path/filepath"
"strconv"
"sync"
"time"
"github.com/solidassassin/session-manager-plugin/src/config"
"github.com/solidassassin/session-manager-plugin/src/log"
"github.com/solidassassin/session-manager-plugin/src/message"
"github.com/solidassassin/session-manager-plugin/src/sessionmanagerplugin/session"
"github.com/solidassassin/session-manager-plugin/src/sessionmanagerplugin/session/sessionutil"
"github.com/solidassassin/session-manager-plugin/src/version"
"github.com/xtaci/smux"
"golang.org/x/sync/errgroup"
)
// MuxClient contains smux client session and corresponding network connection
type MuxClient struct {
conn net.Conn
session *smux.Session
}
// MgsConn contains local server and corresponding connection to smux client
type MgsConn struct {
listener net.Listener
conn net.Conn
}
// MuxPortForwarding is type of port session
// accepts multiple client connections through multiplexing
type MuxPortForwarding struct {
port IPortSession
sessionId string
socketFile string
portParameters PortParameters
session session.Session
muxClient *MuxClient
mgsConn *MgsConn
}
func (c *MgsConn) close() {
c.listener.Close()
c.conn.Close()
}
func (c *MuxClient) close() {
c.session.Close()
c.conn.Close()
}
// IsStreamNotSet checks if stream is not set
func (p *MuxPortForwarding) IsStreamNotSet() (status bool) {
return p.muxClient.conn == nil
}
// Stop closes all open stream
func (p *MuxPortForwarding) Stop() {
if p.mgsConn != nil {
p.mgsConn.close()
}
if p.muxClient != nil {
p.muxClient.close()
}
p.cleanUp()
os.Exit(0)
}
// InitializeStreams initializes i/o streams
func (p *MuxPortForwarding) InitializeStreams(log log.T, agentVersion string, muxKeepAlive bool) (err error) {
p.handleControlSignals(log)
p.socketFile = getUnixSocketPath(p.sessionId, os.TempDir(), "session_manager_plugin_mux.sock")
if err = p.initialize(log, agentVersion, muxKeepAlive); err != nil {
p.cleanUp()
}
return
}
// ReadStream reads data from different connections
func (p *MuxPortForwarding) ReadStream(log log.T) (err error) {
g, ctx := errgroup.WithContext(context.Background())
// reads data from smux client and transfers to server over datachannel
g.Go(func() error {
return p.transferDataToServer(log, ctx)
})
// set up network listener on SSM port and handle client connections
g.Go(func() error {
return p.handleClientConnections(log, ctx)
})
return g.Wait()
}
// WriteStream writes data to stream
func (p *MuxPortForwarding) WriteStream(outputMessage message.ClientMessage) error {
switch message.PayloadType(outputMessage.PayloadType) {
case message.Output:
_, err := p.mgsConn.conn.Write(outputMessage.Payload)
return err
case message.Flag:
var flag message.PayloadTypeFlag
buf := bytes.NewBuffer(outputMessage.Payload)
binary.Read(buf, binary.BigEndian, &flag)
if message.ConnectToPortError == flag {
fmt.Printf("\nConnection to destination port failed, check SSM Agent logs.\n")
}
}
return nil
}
// cleanUp deletes unix socket file
func (p *MuxPortForwarding) cleanUp() {
os.Remove(p.socketFile)
}
// initialize opens a network connection that acts as smux client
func (p *MuxPortForwarding) initialize(log log.T, agentVersion string, muxKeepAlive bool) (err error) {
// open a network listener
var listener net.Listener
if listener, err = sessionutil.NewListener(log, p.socketFile); err != nil {
return
}
var g errgroup.Group
// start a go routine to accept connections on the network listener
g.Go(func() error {
if conn, err := listener.Accept(); err != nil {
return err
} else {
p.mgsConn = &MgsConn{listener, conn}
}
return nil
})
// start a connection to the local network listener and set up client side of mux
g.Go(func() error {
if muxConn, err := net.Dial(listener.Addr().Network(), listener.Addr().String()); err != nil {
return err
} else {
smuxConfig := smux.DefaultConfig()
if version.DoesAgentSupportDisableSmuxKeepAlive(log, agentVersion) {
if !muxKeepAlive {
// Disable smux KeepAlive or else it breaks Session Manager idle timeout.
smuxConfig.KeepAliveDisabled = true
}
}
if muxSession, err := smux.Client(muxConn, smuxConfig); err != nil {
return err
} else {
p.muxClient = &MuxClient{muxConn, muxSession}
}
}
return nil
})
return g.Wait()
}
// handleControlSignals handles terminate signals
func (p *MuxPortForwarding) handleControlSignals(log log.T) {
c := make(chan os.Signal, 1)
signal.Notify(c, sessionutil.ControlSignals...)
go func() {
<-c
fmt.Println("Terminate signal received, exiting.")
if err := p.session.DataChannel.SendFlag(log, message.TerminateSession); err != nil {
log.Errorf("Failed to send TerminateSession flag: %v", err)
}
fmt.Fprintf(os.Stdout, "\n\nExiting session with sessionId: %s.\n\n", p.sessionId)
p.Stop()
}()
}
// transferDataToServer reads from smux client connection and sends on data channel
func (p *MuxPortForwarding) transferDataToServer(log log.T, ctx context.Context) (err error) {
msg := make([]byte, config.StreamDataPayloadSize)
for {
select {
case <-ctx.Done():
return ctx.Err()
default:
var numBytes int
if numBytes, err = p.mgsConn.conn.Read(msg); err != nil {
log.Debugf("Reading from port failed with error: %v.", err)
return
}
log.Tracef("Received message of size %d from mux client.", numBytes)
if err = p.session.DataChannel.SendInputDataMessage(log, message.Output, msg[:numBytes]); err != nil {
log.Errorf("Failed to send packet on data channel: %v", err)
return
}
// sleep to process more data
time.Sleep(time.Millisecond)
}
}
}
// handleClientConnections sets up network server on local ssm port to accept connections from clients (browser/terminal)
func (p *MuxPortForwarding) handleClientConnections(log log.T, ctx context.Context) (err error) {
var (
listener net.Listener
displayMsg string
)
if p.portParameters.LocalConnectionType == "unix" {
if listener, err = net.Listen(p.portParameters.LocalConnectionType, p.portParameters.LocalUnixSocket); err != nil {
return err
}
displayMsg = fmt.Sprintf("Unix socket %s opened for sessionId %s.", p.portParameters.LocalUnixSocket, p.sessionId)
} else {
localPortNumber := p.portParameters.LocalPortNumber
if p.portParameters.LocalPortNumber == "" {
localPortNumber = "0"
}
if listener, err = net.Listen("tcp", "localhost:"+localPortNumber); err != nil {
return err
}
p.portParameters.LocalPortNumber = strconv.Itoa(listener.Addr().(*net.TCPAddr).Port)
displayMsg = fmt.Sprintf("Port %s opened for sessionId %s.", p.portParameters.LocalPortNumber, p.sessionId)
}
defer listener.Close()
log.Infof(displayMsg)
fmt.Printf(displayMsg)
log.Infof("Waiting for connections...\n")
fmt.Printf("\nWaiting for connections...\n")
var once sync.Once
for {
select {
case <-ctx.Done():
return ctx.Err()
default:
if conn, err := listener.Accept(); err != nil {
log.Errorf("Error while accepting connection: %v", err)
} else {
log.Infof("Connection accepted from %s\n for session [%s]", conn.RemoteAddr(), p.sessionId)
once.Do(func() {
fmt.Printf("\nConnection accepted for session [%s]\n", p.sessionId)
})
stream, err := p.muxClient.session.OpenStream()
if err != nil {
continue
}
log.Debugf("Client stream opened %d\n", stream.ID())
go handleDataTransfer(stream, conn)
}
}
}
}
// handleDataTransfer launches routines to transfer data between source and destination
func handleDataTransfer(dst io.ReadWriteCloser, src io.ReadWriteCloser) {
var wait sync.WaitGroup
wait.Add(2)
go func() {
io.Copy(dst, src)
dst.Close()
wait.Done()
}()
go func() {
io.Copy(src, dst)
src.Close()
wait.Done()
}()
wait.Wait()
}
// getUnixSocketPath generates the unix socket file name based on sessionId and returns the path.
func getUnixSocketPath(sessionId string, dir string, suffix string) string {
hash := fnv.New32a()
hash.Write([]byte(sessionId))
return filepath.Join(dir, fmt.Sprintf("%d_%s", hash.Sum32(), suffix))
}