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// Copyright 2011 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package ldap
import (
"crypto/tls"
"errors"
"fmt"
"log"
"net"
"sync"
"time"
"gopkg.in/asn1-ber.v1"
)
const (
MessageQuit = 0
MessageRequest = 1
MessageResponse = 2
MessageFinish = 3
)
type messagePacket struct {
Op int
MessageID int64
Packet *ber.Packet
Channel chan *ber.Packet
}
type sendMessageFlags uint
const (
startTLS sendMessageFlags = 1 << iota
)
// Conn represents an LDAP Connection
type Conn struct {
conn net.Conn
isTLS bool
isClosing bool
isStartingTLS bool
Debug debugging
chanConfirm chan bool
chanResults map[int64]chan *ber.Packet
chanMessage chan *messagePacket
chanMessageID chan int64
wgSender sync.WaitGroup
wgClose sync.WaitGroup
once sync.Once
outstandingRequests uint
messageMutex sync.Mutex
}
var _ Client = &Conn{}
// DefaultTimeout is a package-level variable that sets the timeout value
// used for the Dial and DialTLS methods.
//
// WARNING: since this is a package-level variable, setting this value from
// multiple places will probably result in undesired behaviour.
var DefaultTimeout = 60 * time.Second
// Dial connects to the given address on the given network using net.Dial
// and then returns a new Conn for the connection.
func Dial(network, addr string) (*Conn, error) {
c, err := net.DialTimeout(network, addr, DefaultTimeout)
if err != nil {
return nil, NewError(ErrorNetwork, err)
}
conn := NewConn(c, false)
conn.Start()
return conn, nil
}
// DialTLS connects to the given address on the given network using tls.Dial
// and then returns a new Conn for the connection.
func DialTLS(network, addr string, config *tls.Config) (*Conn, error) {
dc, err := net.DialTimeout(network, addr, DefaultTimeout)
if err != nil {
return nil, NewError(ErrorNetwork, err)
}
c := tls.Client(dc, config)
err = c.Handshake()
if err != nil {
// Handshake error, close the established connection before we return an error
dc.Close()
return nil, NewError(ErrorNetwork, err)
}
conn := NewConn(c, true)
conn.Start()
return conn, nil
}
// NewConn returns a new Conn using conn for network I/O.
func NewConn(conn net.Conn, isTLS bool) *Conn {
return &Conn{
conn: conn,
chanConfirm: make(chan bool),
chanMessageID: make(chan int64),
chanMessage: make(chan *messagePacket, 10),
chanResults: map[int64]chan *ber.Packet{},
isTLS: isTLS,
}
}
func (l *Conn) Start() {
go l.reader()
go l.processMessages()
l.wgClose.Add(1)
}
// Close closes the connection.
func (l *Conn) Close() {
l.once.Do(func() {
l.isClosing = true
l.wgSender.Wait()
l.Debug.Printf("Sending quit message and waiting for confirmation")
l.chanMessage <- &messagePacket{Op: MessageQuit}
<-l.chanConfirm
close(l.chanMessage)
l.Debug.Printf("Closing network connection")
if err := l.conn.Close(); err != nil {
log.Print(err)
}
l.wgClose.Done()
})
l.wgClose.Wait()
}
// Returns the next available messageID
func (l *Conn) nextMessageID() int64 {
if l.chanMessageID != nil {
if messageID, ok := <-l.chanMessageID; ok {
return messageID
}
}
return 0
}
// StartTLS sends the command to start a TLS session and then creates a new TLS Client
func (l *Conn) StartTLS(config *tls.Config) error {
messageID := l.nextMessageID()
if l.isTLS {
return NewError(ErrorNetwork, errors.New("ldap: already encrypted"))
}
packet := ber.Encode(ber.ClassUniversal, ber.TypeConstructed, ber.TagSequence, nil, "LDAP Request")
packet.AppendChild(ber.NewInteger(ber.ClassUniversal, ber.TypePrimitive, ber.TagInteger, messageID, "MessageID"))
request := ber.Encode(ber.ClassApplication, ber.TypeConstructed, ApplicationExtendedRequest, nil, "Start TLS")
request.AppendChild(ber.NewString(ber.ClassContext, ber.TypePrimitive, 0, "1.3.6.1.4.1.1466.20037", "TLS Extended Command"))
packet.AppendChild(request)
l.Debug.PrintPacket(packet)
channel, err := l.sendMessageWithFlags(packet, startTLS)
if err != nil {
return err
}
if channel == nil {
return NewError(ErrorNetwork, errors.New("ldap: could not send message"))
}
l.Debug.Printf("%d: waiting for response", messageID)
packet = <-channel
l.Debug.Printf("%d: got response %p", messageID, packet)
l.finishMessage(messageID)
if l.Debug {
if err := addLDAPDescriptions(packet); err != nil {
l.Close()
return err
}
ber.PrintPacket(packet)
}
if resultCode, message := getLDAPResultCode(packet); resultCode == LDAPResultSuccess {
conn := tls.Client(l.conn, config)
if err := conn.Handshake(); err != nil {
l.Close()
return NewError(ErrorNetwork, fmt.Errorf("TLS handshake failed (%v)", err))
}
l.isTLS = true
l.conn = conn
} else {
return NewError(resultCode, fmt.Errorf("ldap: cannot StartTLS (%s)", message))
}
go l.reader()
return nil
}
func (l *Conn) sendMessage(packet *ber.Packet) (chan *ber.Packet, error) {
return l.sendMessageWithFlags(packet, 0)
}
func (l *Conn) sendMessageWithFlags(packet *ber.Packet, flags sendMessageFlags) (chan *ber.Packet, error) {
if l.isClosing {
return nil, NewError(ErrorNetwork, errors.New("ldap: connection closed"))
}
l.messageMutex.Lock()
l.Debug.Printf("flags&startTLS = %d", flags&startTLS)
if l.isStartingTLS {
l.messageMutex.Unlock()
return nil, NewError(ErrorNetwork, errors.New("ldap: connection is in startls phase."))
}
if flags&startTLS != 0 {
if l.outstandingRequests != 0 {
l.messageMutex.Unlock()
return nil, NewError(ErrorNetwork, errors.New("ldap: cannot StartTLS with outstanding requests"))
} else {
l.isStartingTLS = true
}
}
l.outstandingRequests++
l.messageMutex.Unlock()
out := make(chan *ber.Packet)
message := &messagePacket{
Op: MessageRequest,
MessageID: packet.Children[0].Value.(int64),
Packet: packet,
Channel: out,
}
l.sendProcessMessage(message)
return out, nil
}
func (l *Conn) finishMessage(messageID int64) {
if l.isClosing {
return
}
l.messageMutex.Lock()
l.outstandingRequests--
if l.isStartingTLS {
l.isStartingTLS = false
}
l.messageMutex.Unlock()
message := &messagePacket{
Op: MessageFinish,
MessageID: messageID,
}
l.sendProcessMessage(message)
}
func (l *Conn) sendProcessMessage(message *messagePacket) bool {
if l.isClosing {
return false
}
l.wgSender.Add(1)
l.chanMessage <- message
l.wgSender.Done()
return true
}
func (l *Conn) processMessages() {
defer func() {
if err := recover(); err != nil {
log.Printf("ldap: recovered panic in processMessages: %v", err)
}
for messageID, channel := range l.chanResults {
l.Debug.Printf("Closing channel for MessageID %d", messageID)
close(channel)
delete(l.chanResults, messageID)
}
close(l.chanMessageID)
l.chanConfirm <- true
close(l.chanConfirm)
}()
var messageID int64 = 1
for {
select {
case l.chanMessageID <- messageID:
messageID++
case messagePacket, ok := <-l.chanMessage:
if !ok {
l.Debug.Printf("Shutting down - message channel is closed")
return
}
switch messagePacket.Op {
case MessageQuit:
l.Debug.Printf("Shutting down - quit message received")
return
case MessageRequest:
// Add to message list and write to network
l.Debug.Printf("Sending message %d", messagePacket.MessageID)
l.chanResults[messagePacket.MessageID] = messagePacket.Channel
// go routine
buf := messagePacket.Packet.Bytes()
_, err := l.conn.Write(buf)
if err != nil {
l.Debug.Printf("Error Sending Message: %s", err.Error())
break
}
case MessageResponse:
l.Debug.Printf("Receiving message %d", messagePacket.MessageID)
if chanResult, ok := l.chanResults[messagePacket.MessageID]; ok {
chanResult <- messagePacket.Packet
} else {
log.Printf("Received unexpected message %d", messagePacket.MessageID)
ber.PrintPacket(messagePacket.Packet)
}
case MessageFinish:
// Remove from message list
l.Debug.Printf("Finished message %d", messagePacket.MessageID)
close(l.chanResults[messagePacket.MessageID])
delete(l.chanResults, messagePacket.MessageID)
}
}
}
}
func (l *Conn) reader() {
cleanstop := false
defer func() {
if err := recover(); err != nil {
log.Printf("ldap: recovered panic in reader: %v", err)
}
if !cleanstop {
l.Close()
}
}()
for {
if cleanstop {
l.Debug.Printf("reader clean stopping (without closing the connection)")
return
}
packet, err := ber.ReadPacket(l.conn)
if err != nil {
// A read error is expected here if we are closing the connection...
if !l.isClosing {
l.Debug.Printf("reader error: %s", err.Error())
}
return
}
addLDAPDescriptions(packet)
if len(packet.Children) == 0 {
l.Debug.Printf("Received bad ldap packet")
continue
}
l.messageMutex.Lock()
if l.isStartingTLS {
cleanstop = true
}
l.messageMutex.Unlock()
message := &messagePacket{
Op: MessageResponse,
MessageID: packet.Children[0].Value.(int64),
Packet: packet,
}
if !l.sendProcessMessage(message) {
return
}
}
}
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