390 lines
11 KiB
Go
390 lines
11 KiB
Go
package ldap
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import (
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"bytes"
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"crypto/md5"
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enchex "encoding/hex"
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"errors"
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"fmt"
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"io/ioutil"
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"math/rand"
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"strings"
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ber "github.com/go-asn1-ber/asn1-ber"
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)
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// SimpleBindRequest represents a username/password bind operation
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type SimpleBindRequest struct {
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// Username is the name of the Directory object that the client wishes to bind as
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Username string
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// Password is the credentials to bind with
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Password string
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// Controls are optional controls to send with the bind request
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Controls []Control
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// AllowEmptyPassword sets whether the client allows binding with an empty password
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// (normally used for unauthenticated bind).
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AllowEmptyPassword bool
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}
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// SimpleBindResult contains the response from the server
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type SimpleBindResult struct {
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Controls []Control
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}
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// NewSimpleBindRequest returns a bind request
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func NewSimpleBindRequest(username string, password string, controls []Control) *SimpleBindRequest {
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return &SimpleBindRequest{
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Username: username,
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Password: password,
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Controls: controls,
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AllowEmptyPassword: false,
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}
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}
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func (req *SimpleBindRequest) appendTo(envelope *ber.Packet) error {
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pkt := ber.Encode(ber.ClassApplication, ber.TypeConstructed, ApplicationBindRequest, nil, "Bind Request")
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pkt.AppendChild(ber.NewInteger(ber.ClassUniversal, ber.TypePrimitive, ber.TagInteger, 3, "Version"))
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pkt.AppendChild(ber.NewString(ber.ClassUniversal, ber.TypePrimitive, ber.TagOctetString, req.Username, "User Name"))
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pkt.AppendChild(ber.NewString(ber.ClassContext, ber.TypePrimitive, 0, req.Password, "Password"))
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envelope.AppendChild(pkt)
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if len(req.Controls) > 0 {
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envelope.AppendChild(encodeControls(req.Controls))
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}
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return nil
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}
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// SimpleBind performs the simple bind operation defined in the given request
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func (l *Conn) SimpleBind(simpleBindRequest *SimpleBindRequest) (*SimpleBindResult, error) {
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if simpleBindRequest.Password == "" && !simpleBindRequest.AllowEmptyPassword {
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return nil, NewError(ErrorEmptyPassword, errors.New("ldap: empty password not allowed by the client"))
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}
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msgCtx, err := l.doRequest(simpleBindRequest)
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if err != nil {
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return nil, err
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}
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defer l.finishMessage(msgCtx)
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packet, err := l.readPacket(msgCtx)
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if err != nil {
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return nil, err
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}
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result := &SimpleBindResult{
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Controls: make([]Control, 0),
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}
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if len(packet.Children) == 3 {
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for _, child := range packet.Children[2].Children {
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decodedChild, decodeErr := DecodeControl(child)
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if decodeErr != nil {
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return nil, fmt.Errorf("failed to decode child control: %s", decodeErr)
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}
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result.Controls = append(result.Controls, decodedChild)
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}
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}
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err = GetLDAPError(packet)
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return result, err
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}
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// Bind performs a bind with the given username and password.
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//
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// It does not allow unauthenticated bind (i.e. empty password). Use the UnauthenticatedBind method
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// for that.
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func (l *Conn) Bind(username, password string) error {
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req := &SimpleBindRequest{
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Username: username,
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Password: password,
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AllowEmptyPassword: false,
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}
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_, err := l.SimpleBind(req)
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return err
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}
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// UnauthenticatedBind performs an unauthenticated bind.
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//
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// A username may be provided for trace (e.g. logging) purpose only, but it is normally not
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// authenticated or otherwise validated by the LDAP server.
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//
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// See https://tools.ietf.org/html/rfc4513#section-5.1.2 .
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// See https://tools.ietf.org/html/rfc4513#section-6.3.1 .
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func (l *Conn) UnauthenticatedBind(username string) error {
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req := &SimpleBindRequest{
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Username: username,
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Password: "",
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AllowEmptyPassword: true,
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}
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_, err := l.SimpleBind(req)
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return err
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}
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// DigestMD5BindRequest represents a digest-md5 bind operation
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type DigestMD5BindRequest struct {
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Host string
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// Username is the name of the Directory object that the client wishes to bind as
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Username string
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// Password is the credentials to bind with
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Password string
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// Controls are optional controls to send with the bind request
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Controls []Control
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}
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func (req *DigestMD5BindRequest) appendTo(envelope *ber.Packet) error {
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request := ber.Encode(ber.ClassApplication, ber.TypeConstructed, ApplicationBindRequest, nil, "Bind Request")
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request.AppendChild(ber.NewInteger(ber.ClassUniversal, ber.TypePrimitive, ber.TagInteger, 3, "Version"))
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request.AppendChild(ber.NewString(ber.ClassUniversal, ber.TypePrimitive, ber.TagOctetString, "", "User Name"))
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auth := ber.Encode(ber.ClassContext, ber.TypeConstructed, 3, "", "authentication")
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auth.AppendChild(ber.NewString(ber.ClassUniversal, ber.TypePrimitive, ber.TagOctetString, "DIGEST-MD5", "SASL Mech"))
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request.AppendChild(auth)
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envelope.AppendChild(request)
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if len(req.Controls) > 0 {
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envelope.AppendChild(encodeControls(req.Controls))
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}
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return nil
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}
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// DigestMD5BindResult contains the response from the server
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type DigestMD5BindResult struct {
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Controls []Control
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}
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// MD5Bind performs a digest-md5 bind with the given host, username and password.
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func (l *Conn) MD5Bind(host, username, password string) error {
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req := &DigestMD5BindRequest{
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Host: host,
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Username: username,
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Password: password,
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}
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_, err := l.DigestMD5Bind(req)
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return err
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}
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// DigestMD5Bind performs the digest-md5 bind operation defined in the given request
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func (l *Conn) DigestMD5Bind(digestMD5BindRequest *DigestMD5BindRequest) (*DigestMD5BindResult, error) {
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if digestMD5BindRequest.Password == "" {
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return nil, NewError(ErrorEmptyPassword, errors.New("ldap: empty password not allowed by the client"))
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}
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msgCtx, err := l.doRequest(digestMD5BindRequest)
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if err != nil {
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return nil, err
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}
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defer l.finishMessage(msgCtx)
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packet, err := l.readPacket(msgCtx)
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if err != nil {
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return nil, err
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}
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l.Debug.Printf("%d: got response %p", msgCtx.id, packet)
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if l.Debug {
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if err = addLDAPDescriptions(packet); err != nil {
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return nil, err
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}
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ber.PrintPacket(packet)
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}
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result := &DigestMD5BindResult{
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Controls: make([]Control, 0),
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}
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var params map[string]string
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if len(packet.Children) == 2 {
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if len(packet.Children[1].Children) == 4 {
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child := packet.Children[1].Children[0]
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if child.Tag != ber.TagEnumerated {
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return result, GetLDAPError(packet)
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}
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if child.Value.(int64) != 14 {
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return result, GetLDAPError(packet)
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}
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child = packet.Children[1].Children[3]
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if child.Tag != ber.TagObjectDescriptor {
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return result, GetLDAPError(packet)
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}
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if child.Data == nil {
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return result, GetLDAPError(packet)
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}
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data, _ := ioutil.ReadAll(child.Data)
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params, err = parseParams(string(data))
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if err != nil {
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return result, fmt.Errorf("parsing digest-challenge: %s", err)
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}
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}
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}
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if params != nil {
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resp := computeResponse(
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params,
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"ldap/"+strings.ToLower(digestMD5BindRequest.Host),
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digestMD5BindRequest.Username,
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digestMD5BindRequest.Password,
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)
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packet = ber.Encode(ber.ClassUniversal, ber.TypeConstructed, ber.TagSequence, nil, "LDAP Request")
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packet.AppendChild(ber.NewInteger(ber.ClassUniversal, ber.TypePrimitive, ber.TagInteger, l.nextMessageID(), "MessageID"))
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request := ber.Encode(ber.ClassApplication, ber.TypeConstructed, ApplicationBindRequest, nil, "Bind Request")
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request.AppendChild(ber.NewInteger(ber.ClassUniversal, ber.TypePrimitive, ber.TagInteger, 3, "Version"))
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request.AppendChild(ber.NewString(ber.ClassUniversal, ber.TypePrimitive, ber.TagOctetString, "", "User Name"))
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auth := ber.Encode(ber.ClassContext, ber.TypeConstructed, 3, "", "authentication")
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auth.AppendChild(ber.NewString(ber.ClassUniversal, ber.TypePrimitive, ber.TagOctetString, "DIGEST-MD5", "SASL Mech"))
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auth.AppendChild(ber.NewString(ber.ClassUniversal, ber.TypePrimitive, ber.TagOctetString, resp, "Credentials"))
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request.AppendChild(auth)
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packet.AppendChild(request)
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msgCtx, err = l.sendMessage(packet)
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if err != nil {
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return nil, fmt.Errorf("send message: %s", err)
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}
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defer l.finishMessage(msgCtx)
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packetResponse, ok := <-msgCtx.responses
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if !ok {
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return nil, NewError(ErrorNetwork, errors.New("ldap: response channel closed"))
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}
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packet, err = packetResponse.ReadPacket()
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l.Debug.Printf("%d: got response %p", msgCtx.id, packet)
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if err != nil {
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return nil, fmt.Errorf("read packet: %s", err)
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}
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}
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err = GetLDAPError(packet)
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return result, err
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}
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func parseParams(str string) (map[string]string, error) {
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m := make(map[string]string)
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var key, value string
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var state int
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for i := 0; i <= len(str); i++ {
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switch state {
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case 0: //reading key
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if i == len(str) {
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return nil, fmt.Errorf("syntax error on %d", i)
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}
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if str[i] != '=' {
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key += string(str[i])
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continue
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}
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state = 1
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case 1: //reading value
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if i == len(str) {
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m[key] = value
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break
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}
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switch str[i] {
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case ',':
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m[key] = value
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state = 0
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key = ""
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value = ""
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case '"':
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if value != "" {
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return nil, fmt.Errorf("syntax error on %d", i)
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}
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state = 2
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default:
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value += string(str[i])
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}
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case 2: //inside quotes
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if i == len(str) {
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return nil, fmt.Errorf("syntax error on %d", i)
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}
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if str[i] != '"' {
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value += string(str[i])
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} else {
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state = 1
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}
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}
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}
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return m, nil
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}
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func computeResponse(params map[string]string, uri, username, password string) string {
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nc := "00000001"
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qop := "auth"
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cnonce := enchex.EncodeToString(randomBytes(16))
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x := username + ":" + params["realm"] + ":" + password
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y := md5Hash([]byte(x))
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a1 := bytes.NewBuffer(y)
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a1.WriteString(":" + params["nonce"] + ":" + cnonce)
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if len(params["authzid"]) > 0 {
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a1.WriteString(":" + params["authzid"])
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}
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a2 := bytes.NewBuffer([]byte("AUTHENTICATE"))
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a2.WriteString(":" + uri)
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ha1 := enchex.EncodeToString(md5Hash(a1.Bytes()))
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ha2 := enchex.EncodeToString(md5Hash(a2.Bytes()))
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kd := ha1
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kd += ":" + params["nonce"]
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kd += ":" + nc
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kd += ":" + cnonce
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kd += ":" + qop
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kd += ":" + ha2
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resp := enchex.EncodeToString(md5Hash([]byte(kd)))
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return fmt.Sprintf(
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`username="%s",realm="%s",nonce="%s",cnonce="%s",nc=00000001,qop=%s,digest-uri="%s",response=%s`,
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username,
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params["realm"],
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params["nonce"],
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cnonce,
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qop,
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uri,
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resp,
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)
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}
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func md5Hash(b []byte) []byte {
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hasher := md5.New()
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hasher.Write(b)
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return hasher.Sum(nil)
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}
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func randomBytes(len int) []byte {
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b := make([]byte, len)
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for i := 0; i < len; i++ {
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b[i] = byte(rand.Intn(256))
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}
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return b
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}
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var externalBindRequest = requestFunc(func(envelope *ber.Packet) error {
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pkt := ber.Encode(ber.ClassApplication, ber.TypeConstructed, ApplicationBindRequest, nil, "Bind Request")
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pkt.AppendChild(ber.NewInteger(ber.ClassUniversal, ber.TypePrimitive, ber.TagInteger, 3, "Version"))
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pkt.AppendChild(ber.NewString(ber.ClassUniversal, ber.TypePrimitive, ber.TagOctetString, "", "User Name"))
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saslAuth := ber.Encode(ber.ClassContext, ber.TypeConstructed, 3, "", "authentication")
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saslAuth.AppendChild(ber.NewString(ber.ClassUniversal, ber.TypePrimitive, ber.TagOctetString, "EXTERNAL", "SASL Mech"))
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saslAuth.AppendChild(ber.NewString(ber.ClassUniversal, ber.TypePrimitive, ber.TagOctetString, "", "SASL Cred"))
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pkt.AppendChild(saslAuth)
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envelope.AppendChild(pkt)
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return nil
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})
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// ExternalBind performs SASL/EXTERNAL authentication.
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//
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// Use ldap.DialURL("ldapi://") to connect to the Unix socket before ExternalBind.
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//
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// See https://tools.ietf.org/html/rfc4422#appendix-A
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func (l *Conn) ExternalBind() error {
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msgCtx, err := l.doRequest(externalBindRequest)
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if err != nil {
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return err
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}
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defer l.finishMessage(msgCtx)
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packet, err := l.readPacket(msgCtx)
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if err != nil {
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return err
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}
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return GetLDAPError(packet)
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}
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