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conn.go
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conn.go
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package ldap
import (
"bufio"
"context"
"crypto/tls"
"errors"
"fmt"
"net"
"net/url"
"sync"
"sync/atomic"
"time"
ber "github.com/go-asn1-ber/asn1-ber"
)
const (
// MessageQuit causes the processMessages loop to exit
MessageQuit = 0
// MessageRequest sends a request to the server
MessageRequest = 1
// MessageResponse receives a response from the server
MessageResponse = 2
// MessageFinish indicates the client considers a particular message ID to be finished
MessageFinish = 3
// MessageTimeout indicates the client-specified timeout for a particular message ID has been reached
MessageTimeout = 4
)
const (
// DefaultLdapPort default ldap port for pure TCP connection
DefaultLdapPort = "389"
// DefaultLdapsPort default ldap port for SSL connection
DefaultLdapsPort = "636"
)
// PacketResponse contains the packet or error encountered reading a response
type PacketResponse struct {
// Packet is the packet read from the server
Packet *ber.Packet
// Error is an error encountered while reading
Error error
}
// ReadPacket returns the packet or an error
func (pr *PacketResponse) ReadPacket() (*ber.Packet, error) {
if (pr == nil) || (pr.Packet == nil && pr.Error == nil) {
return nil, NewError(ErrorNetwork, errors.New("ldap: could not retrieve response"))
}
return pr.Packet, pr.Error
}
type messageContext struct {
id int64
// close(done) should only be called from finishMessage()
done chan struct{}
// close(responses) should only be called from processMessages(), and only sent to from sendResponse()
responses chan *PacketResponse
}
// sendResponse should only be called within the processMessages() loop which
// is also responsible for closing the responses channel.
func (msgCtx *messageContext) sendResponse(packet *PacketResponse, timeout time.Duration) {
timeoutCtx := context.Background()
if timeout > 0 {
var cancelFunc context.CancelFunc
timeoutCtx, cancelFunc = context.WithTimeout(context.Background(), timeout)
defer cancelFunc()
}
select {
case msgCtx.responses <- packet:
// Successfully sent packet to message handler.
case <-msgCtx.done:
// The request handler is done and will not receive more
// packets.
case <-timeoutCtx.Done():
// The timeout was reached before the packet was sent.
}
}
type messagePacket struct {
Op int
MessageID int64
Packet *ber.Packet
Context *messageContext
}
type sendMessageFlags uint
const (
startTLS sendMessageFlags = 1 << iota
)
// Conn represents an LDAP Connection
type Conn struct {
// requestTimeout is loaded atomically
// so we need to ensure 64-bit alignment on 32-bit platforms.
// https://github.com/go-ldap/ldap/pull/199
requestTimeout int64
conn net.Conn
isTLS bool
closing uint32
closeErr atomic.Value
isStartingTLS bool
Debug debugging
chanConfirm chan struct{}
messageContexts map[int64]*messageContext
chanMessage chan *messagePacket
chanMessageID chan int64
wgClose sync.WaitGroup
outstandingRequests uint
messageMutex sync.Mutex
err error
}
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
// DialOpt configures DialContext.
type DialOpt func(*DialContext)
// DialWithDialer updates net.Dialer in DialContext.
func DialWithDialer(d *net.Dialer) DialOpt {
return func(dc *DialContext) {
dc.dialer = d
}
}
// DialWithTLSConfig updates tls.Config in DialContext.
func DialWithTLSConfig(tc *tls.Config) DialOpt {
return func(dc *DialContext) {
dc.tlsConfig = tc
}
}
// DialWithTLSDialer is a wrapper for DialWithTLSConfig with the option to
// specify a net.Dialer to for example define a timeout or a custom resolver.
//
// Deprecated: Use DialWithDialer and DialWithTLSConfig instead
func DialWithTLSDialer(tlsConfig *tls.Config, dialer *net.Dialer) DialOpt {
return func(dc *DialContext) {
dc.tlsConfig = tlsConfig
dc.dialer = dialer
}
}
// DialContext contains necessary parameters to dial the given ldap URL.
type DialContext struct {
dialer *net.Dialer
tlsConfig *tls.Config
}
func (dc *DialContext) dial(u *url.URL) (net.Conn, error) {
if u.Scheme == "ldapi" {
if u.Path == "" || u.Path == "/" {
u.Path = "/var/run/slapd/ldapi"
}
return dc.dialer.Dial("unix", u.Path)
}
host, port, err := net.SplitHostPort(u.Host)
if err != nil {
// we assume that error is due to missing port
host = u.Host
port = ""
}
switch u.Scheme {
case "cldap":
if port == "" {
port = DefaultLdapPort
}
return dc.dialer.Dial("udp", net.JoinHostPort(host, port))
case "ldap":
if port == "" {
port = DefaultLdapPort
}
return dc.dialer.Dial("tcp", net.JoinHostPort(host, port))
case "ldaps":
if port == "" {
port = DefaultLdapsPort
}
return tls.DialWithDialer(dc.dialer, "tcp", net.JoinHostPort(host, port), dc.tlsConfig)
}
return nil, fmt.Errorf("Unknown scheme '%s'", u.Scheme)
}
// Dial connects to the given address on the given network using net.Dial
// and then returns a new Conn for the connection.
//
// Deprecated: Use DialURL instead.
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.
//
// Deprecated: Use DialURL instead.
func DialTLS(network, addr string, config *tls.Config) (*Conn, error) {
c, err := tls.DialWithDialer(&net.Dialer{Timeout: DefaultTimeout}, network, addr, config)
if err != nil {
return nil, NewError(ErrorNetwork, err)
}
conn := NewConn(c, true)
conn.Start()
return conn, nil
}
// DialURL connects to the given ldap URL.
// The following schemas are supported: ldap://, ldaps://, ldapi://,
// and cldap:// (RFC1798, deprecated but used by Active Directory).
// On success a new Conn for the connection is returned.
func DialURL(addr string, opts ...DialOpt) (*Conn, error) {
u, err := url.Parse(addr)
if err != nil {
return nil, NewError(ErrorNetwork, err)
}
var dc DialContext
for _, opt := range opts {
opt(&dc)
}
if dc.dialer == nil {
dc.dialer = &net.Dialer{Timeout: DefaultTimeout}
}
c, err := dc.dial(u)
if err != nil {
return nil, NewError(ErrorNetwork, err)
}
conn := NewConn(c, u.Scheme == "ldaps")
conn.Start()
return conn, nil
}
// NewConn returns a new Conn using conn for network I/O.
func NewConn(conn net.Conn, isTLS bool) *Conn {
l := &Conn{
conn: conn,
chanConfirm: make(chan struct{}),
chanMessageID: make(chan int64),
chanMessage: make(chan *messagePacket, 10),
messageContexts: map[int64]*messageContext{},
requestTimeout: 0,
isTLS: isTLS,
}
l.wgClose.Add(1)
return l
}
// Start initialises goroutines to read replies and process messages.
// Warning: Calling this function in addition to Dial or DialURL
// may cause race conditions.
//
// See: https://github.com/go-ldap/ldap/issues/356
func (l *Conn) Start() {
go l.reader()
go l.processMessages()
}
// IsClosing returns whether or not we're currently closing.
func (l *Conn) IsClosing() bool {
return atomic.LoadUint32(&l.closing) == 1
}
// setClosing sets the closing value to true
func (l *Conn) setClosing() bool {
return atomic.CompareAndSwapUint32(&l.closing, 0, 1)
}
// Close closes the connection.
func (l *Conn) Close() (err error) {
l.messageMutex.Lock()
defer l.messageMutex.Unlock()
if l.setClosing() {
l.Debug.Printf("Sending quit message and waiting for confirmation")
l.chanMessage <- &messagePacket{Op: MessageQuit}
timeoutCtx := context.Background()
if l.getTimeout() > 0 {
var cancelFunc context.CancelFunc
timeoutCtx, cancelFunc = context.WithTimeout(timeoutCtx, time.Duration(l.getTimeout()))
defer cancelFunc()
}
select {
case <-l.chanConfirm:
// Confirmation was received.
case <-timeoutCtx.Done():
// The timeout was reached before confirmation was received.
}
close(l.chanMessage)
l.Debug.Printf("Closing network connection")
err = l.conn.Close()
l.wgClose.Done()
}
l.wgClose.Wait()
return err
}
// SetTimeout sets the time after a request is sent that a MessageTimeout triggers
func (l *Conn) SetTimeout(timeout time.Duration) {
atomic.StoreInt64(&l.requestTimeout, int64(timeout))
}
func (l *Conn) getTimeout() int64 {
return atomic.LoadInt64(&l.requestTimeout)
}
// Returns the next available messageID
func (l *Conn) nextMessageID() int64 {
if messageID, ok := <-l.chanMessageID; ok {
return messageID
}
return 0
}
// GetLastError returns the last recorded error from goroutines like processMessages and reader.
// Only the last recorded error will be returned.
func (l *Conn) GetLastError() error {
l.messageMutex.Lock()
defer l.messageMutex.Unlock()
return l.err
}
// StartTLS sends the command to start a TLS session and then creates a new TLS Client
func (l *Conn) StartTLS(config *tls.Config) error {
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, l.nextMessageID(), "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)
msgCtx, err := l.sendMessageWithFlags(packet, startTLS)
if err != nil {
return err
}
defer l.finishMessage(msgCtx)
l.Debug.Printf("%d: waiting for response", msgCtx.id)
packetResponse, ok := <-msgCtx.responses
if !ok {
return NewError(ErrorNetwork, errors.New("ldap: response channel closed"))
}
packet, err = packetResponse.ReadPacket()
l.Debug.Printf("%d: got response %p", msgCtx.id, packet)
if err != nil {
return err
}
if l.Debug {
if err := addLDAPDescriptions(packet); err != nil {
l.Close()
return err
}
l.Debug.PrintPacket(packet)
}
if err := GetLDAPError(packet); err == nil {
conn := tls.Client(l.conn, config)
if connErr := conn.Handshake(); connErr != nil {
l.Close()
return NewError(ErrorNetwork, fmt.Errorf("TLS handshake failed (%v)", connErr))
}
l.isTLS = true
l.conn = conn
} else {
return err
}
go l.reader()
return nil
}
// TLSConnectionState returns the client's TLS connection state.
// The return values are their zero values if StartTLS did
// not succeed.
func (l *Conn) TLSConnectionState() (state tls.ConnectionState, ok bool) {
tc, ok := l.conn.(*tls.Conn)
if !ok {
return
}
return tc.ConnectionState(), true
}
func (l *Conn) sendMessage(packet *ber.Packet) (*messageContext, error) {
return l.sendMessageWithFlags(packet, 0)
}
func (l *Conn) sendMessageWithFlags(packet *ber.Packet, flags sendMessageFlags) (*messageContext, 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"))
}
l.isStartingTLS = true
}
l.outstandingRequests++
l.messageMutex.Unlock()
responses := make(chan *PacketResponse)
messageID := packet.Children[0].Value.(int64)
message := &messagePacket{
Op: MessageRequest,
MessageID: messageID,
Packet: packet,
Context: &messageContext{
id: messageID,
done: make(chan struct{}),
responses: responses,
},
}
if !l.sendProcessMessage(message) {
if l.IsClosing() {
return nil, NewError(ErrorNetwork, errors.New("ldap: connection closed"))
}
return nil, NewError(ErrorNetwork, errors.New("ldap: could not send message for unknown reason"))
}
return message.Context, nil
}
func (l *Conn) finishMessage(msgCtx *messageContext) {
close(msgCtx.done)
if l.IsClosing() {
return
}
l.messageMutex.Lock()
l.outstandingRequests--
if l.isStartingTLS {
l.isStartingTLS = false
}
l.messageMutex.Unlock()
message := &messagePacket{
Op: MessageFinish,
MessageID: msgCtx.id,
}
l.sendProcessMessage(message)
}
func (l *Conn) sendProcessMessage(message *messagePacket) bool {
l.messageMutex.Lock()
defer l.messageMutex.Unlock()
if l.IsClosing() {
return false
}
l.chanMessage <- message
return true
}
func (l *Conn) processMessages() {
defer func() {
if err := recover(); err != nil {
l.err = fmt.Errorf("ldap: recovered panic in processMessages: %v", err)
}
for messageID, msgCtx := range l.messageContexts {
// If we are closing due to an error, inform anyone who
// is waiting about the error.
if l.IsClosing() && l.closeErr.Load() != nil {
msgCtx.sendResponse(&PacketResponse{Error: l.closeErr.Load().(error)}, time.Duration(l.getTimeout()))
}
l.Debug.Printf("Closing channel for MessageID %d", messageID)
close(msgCtx.responses)
delete(l.messageContexts, messageID)
}
close(l.chanMessageID)
close(l.chanConfirm)
}()
var messageID int64 = 1
for {
select {
case l.chanMessageID <- messageID:
messageID++
case message := <-l.chanMessage:
switch message.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", message.MessageID)
buf := message.Packet.Bytes()
_, err := l.conn.Write(buf)
if err != nil {
l.Debug.Printf("Error Sending Message: %s", err.Error())
message.Context.sendResponse(&PacketResponse{Error: fmt.Errorf("unable to send request: %s", err)}, time.Duration(l.getTimeout()))
close(message.Context.responses)
break
}
// Only add to messageContexts if we were able to
// successfully write the message.
l.messageContexts[message.MessageID] = message.Context
// Add timeout if defined
requestTimeout := l.getTimeout()
if requestTimeout > 0 {
go func() {
timer := time.NewTimer(time.Duration(requestTimeout))
defer func() {
if err := recover(); err != nil {
l.err = fmt.Errorf("ldap: recovered panic in RequestTimeout: %v", err)
}
timer.Stop()
}()
select {
case <-timer.C:
timeoutMessage := &messagePacket{
Op: MessageTimeout,
MessageID: message.MessageID,
}
l.sendProcessMessage(timeoutMessage)
case <-message.Context.done:
}
}()
}
case MessageResponse:
l.Debug.Printf("Receiving message %d", message.MessageID)
if msgCtx, ok := l.messageContexts[message.MessageID]; ok {
msgCtx.sendResponse(&PacketResponse{message.Packet, nil}, time.Duration(l.getTimeout()))
} else {
l.err = fmt.Errorf("ldap: received unexpected message %d, %v", message.MessageID, l.IsClosing())
l.Debug.PrintPacket(message.Packet)
}
case MessageTimeout:
// Handle the timeout by closing the channel
// All reads will return immediately
if msgCtx, ok := l.messageContexts[message.MessageID]; ok {
l.Debug.Printf("Receiving message timeout for %d", message.MessageID)
msgCtx.sendResponse(&PacketResponse{message.Packet, NewError(ErrorNetwork, errors.New("ldap: connection timed out"))}, time.Duration(l.getTimeout()))
delete(l.messageContexts, message.MessageID)
close(msgCtx.responses)
}
case MessageFinish:
l.Debug.Printf("Finished message %d", message.MessageID)
if msgCtx, ok := l.messageContexts[message.MessageID]; ok {
delete(l.messageContexts, message.MessageID)
close(msgCtx.responses)
}
}
}
}
}
func (l *Conn) reader() {
cleanstop := false
defer func() {
if err := recover(); err != nil {
l.err = fmt.Errorf("ldap: recovered panic in reader: %v", err)
}
if !cleanstop {
l.Close()
}
}()
bufConn := bufio.NewReader(l.conn)
for {
if cleanstop {
l.Debug.Printf("reader clean stopping (without closing the connection)")
return
}
packet, err := ber.ReadPacket(bufConn)
if err != nil {
// A read error is expected here if we are closing the connection...
if !l.IsClosing() {
l.closeErr.Store(fmt.Errorf("unable to read LDAP response packet: %s", err))
l.Debug.Printf("reader error: %s", err)
}
return
}
if err := addLDAPDescriptions(packet); err != nil {
l.Debug.Printf("descriptions error: %s", err)
}
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
}
}
}