Support dual login via LDAP and forms authentication

Closes #256 as we now support dual login -- LDAP and forms authentication.

Also bumped the vendored library to LDAP.v3 as it contains bug fixes.

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

@@ -0,0 +1,84 @@
+//
+// https://tools.ietf.org/html/rfc4511
+//
+// DelRequest ::= [APPLICATION 10] LDAPDN
+
+package ldap
+
+import (
+	"errors"
+	"log"
+
+	"gopkg.in/asn1-ber.v1"
+)
+
+// DelRequest implements an LDAP deletion request
+type DelRequest struct {
+	// DN is the name of the directory entry to delete
+	DN string
+	// Controls hold optional controls to send with the request
+	Controls []Control
+}
+
+func (d DelRequest) encode() *ber.Packet {
+	request := ber.Encode(ber.ClassApplication, ber.TypePrimitive, ApplicationDelRequest, d.DN, "Del Request")
+	request.Data.Write([]byte(d.DN))
+	return request
+}
+
+// NewDelRequest creates a delete request for the given DN and controls
+func NewDelRequest(DN string,
+	Controls []Control) *DelRequest {
+	return &DelRequest{
+		DN:       DN,
+		Controls: Controls,
+	}
+}
+
+// Del executes the given delete request
+func (l *Conn) Del(delRequest *DelRequest) 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"))
+	packet.AppendChild(delRequest.encode())
+	if len(delRequest.Controls) > 0 {
+		packet.AppendChild(encodeControls(delRequest.Controls))
+	}
+
+	l.Debug.PrintPacket(packet)
+
+	msgCtx, err := l.sendMessage(packet)
+	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 {
+			return err
+		}
+		ber.PrintPacket(packet)
+	}
+
+	if packet.Children[1].Tag == ApplicationDelResponse {
+		err := GetLDAPError(packet)
+		if err != nil {
+			return err
+		}
+	} else {
+		log.Printf("Unexpected Response: %d", packet.Children[1].Tag)
+	}
+
+	l.Debug.Printf("%d: returning", msgCtx.id)
+	return nil
+}