Move to ldap.v3 to fix #5928 (#6105)

Signed-off-by: Andrew Thornton <art27@cantab.net>

vendor/gopkg.in/ldap.v3/compare.go

@@ -0,0 +1,83 @@
+// File contains Compare functionality
+//
+// https://tools.ietf.org/html/rfc4511
+//
+// CompareRequest ::= [APPLICATION 14] SEQUENCE {
+//              entry           LDAPDN,
+//              ava             AttributeValueAssertion }
+//
+// AttributeValueAssertion ::= SEQUENCE {
+//              attributeDesc   AttributeDescription,
+//              assertionValue  AssertionValue }
+//
+// AttributeDescription ::= LDAPString
+//                         -- Constrained to <attributedescription>
+//                         -- [RFC4512]
+//
+// AttributeValue ::= OCTET STRING
+//
+
+package ldap
+
+import (
+	"errors"
+	"fmt"
+
+	"gopkg.in/asn1-ber.v1"
+)
+
+// Compare checks to see if the attribute of the dn matches value. Returns true if it does otherwise
+// false with any error that occurs if any.
+func (l *Conn) Compare(dn, attribute, value string) (bool, error) {
+	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, ApplicationCompareRequest, nil, "Compare Request")
+	request.AppendChild(ber.NewString(ber.ClassUniversal, ber.TypePrimitive, ber.TagOctetString, dn, "DN"))
+
+	ava := ber.Encode(ber.ClassUniversal, ber.TypeConstructed, ber.TagSequence, nil, "AttributeValueAssertion")
+	ava.AppendChild(ber.NewString(ber.ClassUniversal, ber.TypePrimitive, ber.TagOctetString, attribute, "AttributeDesc"))
+	ava.AppendChild(ber.Encode(ber.ClassUniversal, ber.TypePrimitive, ber.TagOctetString, value, "AssertionValue"))
+	request.AppendChild(ava)
+	packet.AppendChild(request)
+
+	l.Debug.PrintPacket(packet)
+
+	msgCtx, err := l.sendMessage(packet)
+	if err != nil {
+		return false, err
+	}
+	defer l.finishMessage(msgCtx)
+
+	l.Debug.Printf("%d: waiting for response", msgCtx.id)
+	packetResponse, ok := <-msgCtx.responses
+	if !ok {
+		return false, 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 false, err
+	}
+
+	if l.Debug {
+		if err := addLDAPDescriptions(packet); err != nil {
+			return false, err
+		}
+		ber.PrintPacket(packet)
+	}
+
+	if packet.Children[1].Tag == ApplicationCompareResponse {
+		err := GetLDAPError(packet)
+
+		switch {
+		case IsErrorWithCode(err, LDAPResultCompareTrue):
+			return true, nil
+		case IsErrorWithCode(err, LDAPResultCompareFalse):
+			return false, nil
+		default:
+			return false, err
+		}
+	}
+	return false, fmt.Errorf("unexpected Response: %d", packet.Children[1].Tag)
+}