Add DIGEST-MD5 bind support

bind.go

@@ -1,8 +1,14 @@
 package ldap
 
 import (
+	"bytes"
+	"crypto/md5"
+	enchex "encoding/hex"
 	"errors"
 	"fmt"
+	"io/ioutil"
+	"math/rand"
+	"strings"
 
 	ber "github.com/go-asn1-ber/asn1-ber"
 )
@@ -115,6 +121,237 @@ func (l *Conn) UnauthenticatedBind(username string) error {
 	return err
 }
 
+// DigestMD5BindRequest represents a digest-md5 bind operation
+type DigestMD5BindRequest struct {
+	Host string
+	// Username is the name of the Directory object that the client wishes to bind as
+	Username string
+	// Password is the credentials to bind with
+	Password string
+	// Controls are optional controls to send with the bind request
+	Controls []Control
+}
+
+func (req *DigestMD5BindRequest) appendTo(envelope *ber.Packet) error {
+	request := ber.Encode(ber.ClassApplication, ber.TypeConstructed, ApplicationBindRequest, nil, "Bind Request")
+	request.AppendChild(ber.NewInteger(ber.ClassUniversal, ber.TypePrimitive, ber.TagInteger, 3, "Version"))
+	request.AppendChild(ber.NewString(ber.ClassUniversal, ber.TypePrimitive, ber.TagOctetString, "", "User Name"))
+
+	auth := ber.Encode(ber.ClassContext, ber.TypeConstructed, 3, "", "authentication")
+	auth.AppendChild(ber.NewString(ber.ClassUniversal, ber.TypePrimitive, ber.TagOctetString, "DIGEST-MD5", "SASL Mech"))
+	request.AppendChild(auth)
+	envelope.AppendChild(request)
+	if len(req.Controls) > 0 {
+		envelope.AppendChild(encodeControls(req.Controls))
+	}
+	return nil
+}
+
+// DigestMD5BindResult contains the response from the server
+type DigestMD5BindResult struct {
+	Controls []Control
+}
+
+// MD5Bind performs a digest-md5 bind with the given host, username and password.
+func (l *Conn) MD5Bind(host, username, password string) error {
+	req := &DigestMD5BindRequest{
+		Host:     host,
+		Username: username,
+		Password: password,
+	}
+	_, err := l.DigestMD5Bind(req)
+	return err
+}
+
+// DigestMD5Bind performs the digest-md5 bind operation defined in the given request
+func (l *Conn) DigestMD5Bind(digestMD5BindRequest *DigestMD5BindRequest) (*DigestMD5BindResult, error) {
+	if digestMD5BindRequest.Password == "" {
+		return nil, NewError(ErrorEmptyPassword, errors.New("ldap: empty password not allowed by the client"))
+	}
+
+	msgCtx, err := l.doRequest(digestMD5BindRequest)
+	if err != nil {
+		return nil, err
+	}
+	defer l.finishMessage(msgCtx)
+
+	packet, err := l.readPacket(msgCtx)
+	if err != nil {
+		return nil, err
+	}
+	l.Debug.Printf("%d: got response %p", msgCtx.id, packet)
+	if l.Debug {
+		if err = addLDAPDescriptions(packet); err != nil {
+			return nil, err
+		}
+		ber.PrintPacket(packet)
+	}
+
+	result := &DigestMD5BindResult{
+		Controls: make([]Control, 0),
+	}
+	var params map[string]string
+	if len(packet.Children) == 2 {
+		if len(packet.Children[1].Children) == 4 {
+			child := packet.Children[1].Children[0]
+			if child.Tag != ber.TagEnumerated {
+				return result, GetLDAPError(packet)
+			}
+			if child.Value.(int64) != 14 {
+				return result, GetLDAPError(packet)
+			}
+			child = packet.Children[1].Children[3]
+			if child.Tag != ber.TagObjectDescriptor {
+				return result, GetLDAPError(packet)
+			}
+			if child.Data == nil {
+				return result, GetLDAPError(packet)
+			}
+			data, _ := ioutil.ReadAll(child.Data)
+			params, err = parseParams(string(data))
+			if err != nil {
+				return result, fmt.Errorf("parsing digest-challenge: %s", err)
+			}
+		}
+	}
+
+	if params != nil {
+		resp := computeResponse(
+			params,
+			"ldap/"+strings.ToLower(digestMD5BindRequest.Host),
+			digestMD5BindRequest.Username,
+			digestMD5BindRequest.Password,
+		)
+		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, ApplicationBindRequest, nil, "Bind Request")
+		request.AppendChild(ber.NewInteger(ber.ClassUniversal, ber.TypePrimitive, ber.TagInteger, 3, "Version"))
+		request.AppendChild(ber.NewString(ber.ClassUniversal, ber.TypePrimitive, ber.TagOctetString, "", "User Name"))
+
+		auth := ber.Encode(ber.ClassContext, ber.TypeConstructed, 3, "", "authentication")
+		auth.AppendChild(ber.NewString(ber.ClassUniversal, ber.TypePrimitive, ber.TagOctetString, "DIGEST-MD5", "SASL Mech"))
+		auth.AppendChild(ber.NewString(ber.ClassUniversal, ber.TypePrimitive, ber.TagOctetString, resp, "Credentials"))
+		request.AppendChild(auth)
+		packet.AppendChild(request)
+		msgCtx, err = l.sendMessage(packet)
+		if err != nil {
+			return nil, fmt.Errorf("send message: %s", err)
+		}
+		defer l.finishMessage(msgCtx)
+		packetResponse, ok := <-msgCtx.responses
+		if !ok {
+			return nil, 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 nil, fmt.Errorf("read packet: %s", err)
+		}
+	}
+
+	err = GetLDAPError(packet)
+	return result, err
+}
+
+func parseParams(str string) (map[string]string, error) {
+	m := make(map[string]string)
+	var key, value string
+	var state int
+	for i := 0; i <= len(str); i++ {
+		switch state {
+		case 0: //reading key
+			if i == len(str) {
+				return nil, fmt.Errorf("syntax error on %d", i)
+			}
+			if str[i] != '=' {
+				key += string(str[i])
+				continue
+			}
+			state = 1
+		case 1: //reading value
+			if i == len(str) {
+				m[key] = value
+				break
+			}
+			switch str[i] {
+			case ',':
+				m[key] = value
+				state = 0
+				key = ""
+				value = ""
+			case '"':
+				if value != "" {
+					return nil, fmt.Errorf("syntax error on %d", i)
+				}
+				state = 2
+			default:
+				value += string(str[i])
+			}
+		case 2: //inside quotes
+			if i == len(str) {
+				return nil, fmt.Errorf("syntax error on %d", i)
+			}
+			if str[i] != '"' {
+				value += string(str[i])
+			} else {
+				state = 1
+			}
+		}
+	}
+	return m, nil
+}
+
+func computeResponse(params map[string]string, uri, username, password string) string {
+	nc := "00000001"
+	qop := "auth"
+	cnonce := enchex.EncodeToString(randomBytes(16))
+	x := username + ":" + params["realm"] + ":" + password
+	y := md5Hash([]byte(x))
+
+	a1 := bytes.NewBuffer(y)
+	a1.WriteString(":" + params["nonce"] + ":" + cnonce)
+	if len(params["authzid"]) > 0 {
+		a1.WriteString(":" + params["authzid"])
+	}
+	a2 := bytes.NewBuffer([]byte("AUTHENTICATE"))
+	a2.WriteString(":" + uri)
+	ha1 := enchex.EncodeToString(md5Hash(a1.Bytes()))
+	ha2 := enchex.EncodeToString(md5Hash(a2.Bytes()))
+
+	kd := ha1
+	kd += ":" + params["nonce"]
+	kd += ":" + nc
+	kd += ":" + cnonce
+	kd += ":" + qop
+	kd += ":" + ha2
+	resp := enchex.EncodeToString(md5Hash([]byte(kd)))
+	return fmt.Sprintf(
+		`username="%s",realm="%s",nonce="%s",cnonce="%s",nc=00000001,qop=%s,digest-uri="%s",response=%s`,
+		username,
+		params["realm"],
+		params["nonce"],
+		cnonce,
+		qop,
+		uri,
+		resp,
+	)
+}
+
+func md5Hash(b []byte) []byte {
+	hasher := md5.New()
+	hasher.Write(b)
+	return hasher.Sum(nil)
+}
+
+func randomBytes(len int) []byte {
+	b := make([]byte, len)
+	for i := 0; i < len; i++ {
+		b[i] = byte(rand.Intn(256))
+	}
+	return b
+}
+
 var externalBindRequest = requestFunc(func(envelope *ber.Packet) error {
 	pkt := ber.Encode(ber.ClassApplication, ber.TypeConstructed, ApplicationBindRequest, nil, "Bind Request")
 	pkt.AppendChild(ber.NewInteger(ber.ClassUniversal, ber.TypePrimitive, ber.TagInteger, 3, "Version"))

go.mod

@@ -2,4 +2,7 @@ module github.com/go-ldap/ldap
 
 go 1.13
 
-require github.com/go-asn1-ber/asn1-ber v1.3.1
+require (
+	github.com/go-asn1-ber/asn1-ber v1.3.1
+	github.com/go-ldap/ldap v3.0.3+incompatible // indirect
+)

go.sum

@@ -1,2 +1,4 @@
 github.com/go-asn1-ber/asn1-ber v1.3.1 h1:gvPdv/Hr++TRFCl0UbPFHC54P9N9jgsRPnmnr419Uck=
 github.com/go-asn1-ber/asn1-ber v1.3.1/go.mod h1:hEBeB/ic+5LoWskz+yKT7vGhhPYkProFKoKdwZRWMe0=
+github.com/go-ldap/ldap v3.0.3+incompatible h1:HTeSZO8hWMS1Rgb2Ziku6b8a7qRIZZMHjsvuZyatzwk=
+github.com/go-ldap/ldap v3.0.3+incompatible/go.mod h1:qfd9rJvER9Q0/D/Sqn1DfHRoBp40uXYvFoEVrNEPqRc=