mirror of
https://github.com/gravitational/teleport
synced 2024-10-21 17:53:28 +00:00
266 lines
7 KiB
Go
266 lines
7 KiB
Go
/*
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Copyright 2015 Gravitational, Inc.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package reversetunnel
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import (
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"fmt"
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"io/ioutil"
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"net"
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"net/http"
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"strings"
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"sync"
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"time"
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"github.com/gravitational/roundtrip"
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"github.com/gravitational/teleport/lib/auth"
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"github.com/gravitational/teleport/lib/defaults"
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"github.com/gravitational/teleport/lib/utils"
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"github.com/gravitational/trace"
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log "github.com/Sirupsen/logrus"
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"github.com/mailgun/oxy/forward"
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"golang.org/x/crypto/ssh"
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)
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// remoteSite is a remote site who established the inbound connecton to
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// the local reverse tunnel server, and now it can provide access to the
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// cluster behind it.
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type remoteSite struct {
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sync.Mutex
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log *log.Entry
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domainName string
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connections []*remoteConn
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lastUsed int
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lastActive time.Time
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srv *server
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transport *http.Transport
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clt *auth.Client
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accessPoint auth.AccessPoint
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}
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func (s *remoteSite) CachingAccessPoint() (auth.AccessPoint, error) {
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return s.accessPoint, nil
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}
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func (s *remoteSite) GetClient() (auth.ClientI, error) {
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return s.clt, nil
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}
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func (s *remoteSite) String() string {
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return fmt.Sprintf("remoteSite(%v)", s.domainName)
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}
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func (s *remoteSite) connectionCount() int {
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s.Lock()
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defer s.Unlock()
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return len(s.connections)
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}
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func (s *remoteSite) nextConn() (*remoteConn, error) {
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s.Lock()
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defer s.Unlock()
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for {
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if len(s.connections) == 0 {
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return nil, trace.NotFound("no active tunnels to cluster %v", s.GetName())
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}
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s.lastUsed = (s.lastUsed + 1) % len(s.connections)
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remoteConn := s.connections[s.lastUsed]
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if !remoteConn.isInvalid() {
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return remoteConn, nil
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}
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s.connections = append(s.connections[:s.lastUsed], s.connections[s.lastUsed+1:]...)
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s.lastUsed = 0
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go remoteConn.Close()
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}
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}
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// addConn helper adds a new active remote cluster connection to the list
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// of such connections
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func (s *remoteSite) addConn(conn net.Conn, sshConn ssh.Conn) (*remoteConn, error) {
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rc := &remoteConn{
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sshConn: sshConn,
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conn: conn,
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log: s.log,
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}
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s.Lock()
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defer s.Unlock()
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s.connections = append(s.connections, rc)
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s.lastUsed = 0
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return rc, nil
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}
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func (s *remoteSite) GetStatus() string {
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s.Lock()
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defer s.Unlock()
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diff := time.Now().Sub(s.lastActive)
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if diff > 2*defaults.ReverseTunnelAgentHeartbeatPeriod {
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return RemoteSiteStatusOffline
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}
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return RemoteSiteStatusOnline
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}
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func (s *remoteSite) setLastActive(t time.Time) {
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s.Lock()
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defer s.Unlock()
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s.lastActive = t
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}
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func (s *remoteSite) handleHeartbeat(conn *remoteConn, ch ssh.Channel, reqC <-chan *ssh.Request) {
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defer func() {
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s.log.Infof("[TUNNEL] site connection closed: %v", s.domainName)
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conn.Close()
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}()
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for {
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select {
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case req := <-reqC:
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if req == nil {
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s.log.Infof("[TUNNEL] site disconnected: %v", s.domainName)
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conn.markInvalid(trace.ConnectionProblem(nil, "agent disconnected"))
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return
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}
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log.Debugf("[TUNNEL] ping from \"%s\" %s", s.domainName, conn.conn.RemoteAddr())
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s.setLastActive(time.Now())
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case <-time.After(3 * defaults.ReverseTunnelAgentHeartbeatPeriod):
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conn.markInvalid(trace.ConnectionProblem(nil, "agent missed 3 heartbeats"))
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}
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}
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}
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func (s *remoteSite) GetName() string {
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return s.domainName
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}
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func (s *remoteSite) GetLastConnected() time.Time {
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s.Lock()
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defer s.Unlock()
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return s.lastActive
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}
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// dialAccessPoint establishes a connection from the proxy (reverse tunnel server)
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// back into the client using previously established tunnel.
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func (s *remoteSite) dialAccessPoint(network, addr string) (net.Conn, error) {
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s.log.Infof("[TUNNEL] dial to site '%s'", s.GetName())
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try := func() (net.Conn, error) {
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remoteConn, err := s.nextConn()
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if err != nil {
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return nil, trace.Wrap(err)
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}
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ch, _, err := remoteConn.sshConn.OpenChannel(chanAccessPoint, nil)
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if err != nil {
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remoteConn.markInvalid(err)
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s.log.Errorf("[TUNNEL] disconnecting site '%s' on %v. Err: %v",
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s.GetName(),
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remoteConn.conn.RemoteAddr(),
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err)
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return nil, trace.Wrap(err)
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}
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s.log.Infof("[TUNNEL] success dialing to site '%s'", s.GetName())
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return utils.NewChConn(remoteConn.sshConn, ch), nil
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}
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for {
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conn, err := try()
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if err != nil {
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if trace.IsNotFound(err) {
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return nil, trace.Wrap(err)
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}
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continue
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}
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return conn, nil
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}
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}
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// Dial is used to connect a requesting client (say, tsh) to an SSH server
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// located in a remote connected site, the connection goes through the
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// reverse proxy tunnel.
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func (s *remoteSite) Dial(from, to net.Addr) (conn net.Conn, err error) {
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s.log.Infof("[TUNNEL] dialing %v@%v through the tunnel", to, s.domainName)
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stop := false
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_, addr := to.Network(), to.String()
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try := func() (net.Conn, error) {
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remoteConn, err := s.nextConn()
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if err != nil {
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return nil, trace.Wrap(err)
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}
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var ch ssh.Channel
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ch, _, err = remoteConn.sshConn.OpenChannel(chanTransport, nil)
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if err != nil {
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remoteConn.markInvalid(err)
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return nil, trace.Wrap(err)
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}
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stop = true
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// send a special SSH out-of-band request called "teleport-transport"
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// the agent on the other side will create a new TCP/IP connection to
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// 'addr' on its network and will start proxying that connection over
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// this SSH channel:
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var dialed bool
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dialed, err = ch.SendRequest(chanTransportDialReq, true, []byte(addr))
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if err != nil {
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return nil, trace.Wrap(err)
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}
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if !dialed {
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defer ch.Close()
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// pull the error message from the tunnel client (remote cluster)
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// passed to us via stderr:
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errMessage, _ := ioutil.ReadAll(ch.Stderr())
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if errMessage == nil {
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errMessage = []byte("failed connecting to " + addr)
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}
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return nil, trace.Errorf(strings.TrimSpace(string(errMessage)))
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}
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return utils.NewChConn(remoteConn.sshConn, ch), nil
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}
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// loop through existing TCP/IP connections (reverse tunnels) and try
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// to establish an inbound connection-over-ssh-channel to the remote
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// cluster (AKA "remotetunnel agent"):
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for i := 0; i < s.connectionCount() && !stop; i++ {
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conn, err = try()
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if err == nil {
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return conn, nil
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}
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s.log.Errorf("[TUNNEL] Dial(addr=%v) failed: %v", addr, err)
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}
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// didn't connect and no error? this means we didn't have any connected
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// tunnels to try
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if err == nil {
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err = trace.Errorf("%v is offline", s.GetName())
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}
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return nil, err
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}
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func (s *remoteSite) handleAuthProxy(w http.ResponseWriter, r *http.Request) {
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s.log.Infof("[TUNNEL] handleAuthProxy()")
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fwd, err := forward.New(forward.RoundTripper(s.transport), forward.Logger(s.log))
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if err != nil {
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roundtrip.ReplyJSON(w, http.StatusInternalServerError, err.Error())
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return
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}
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r.URL.Scheme = "http"
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r.URL.Host = "stub"
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fwd.ServeHTTP(w, r)
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}
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