diff --git a/vendor/gopkg.in/jcmturner/gokrb5.v7/client/ASExchange.go b/vendor/gopkg.in/jcmturner/gokrb5.v7/client/ASExchange.go
new file mode 100644
index 0000000..9d1a2f3
--- /dev/null
+++ b/vendor/gopkg.in/jcmturner/gokrb5.v7/client/ASExchange.go
@@ -0,0 +1,189 @@
+package client
+
+import (
+	"gopkg.in/jcmturner/gokrb5.v7/crypto"
+	"gopkg.in/jcmturner/gokrb5.v7/crypto/etype"
+	"gopkg.in/jcmturner/gokrb5.v7/iana/errorcode"
+	"gopkg.in/jcmturner/gokrb5.v7/iana/keyusage"
+	"gopkg.in/jcmturner/gokrb5.v7/iana/patype"
+	"gopkg.in/jcmturner/gokrb5.v7/krberror"
+	"gopkg.in/jcmturner/gokrb5.v7/messages"
+	"gopkg.in/jcmturner/gokrb5.v7/types"
+)
+
+// ASExchange performs an AS exchange for the client to retrieve a TGT.
+func (cl *Client) ASExchange(realm string, ASReq messages.ASReq, referral int) (messages.ASRep, error) {
+	if ok, err := cl.IsConfigured(); !ok {
+		return messages.ASRep{}, krberror.Errorf(err, krberror.ConfigError, "AS Exchange cannot be performed")
+	}
+
+	// Set PAData if required
+	err := setPAData(cl, nil, &ASReq)
+	if err != nil {
+		return messages.ASRep{}, krberror.Errorf(err, krberror.KRBMsgError, "AS Exchange Error: issue with setting PAData on AS_REQ")
+	}
+
+	b, err := ASReq.Marshal()
+	if err != nil {
+		return messages.ASRep{}, krberror.Errorf(err, krberror.EncodingError, "AS Exchange Error: failed marshaling AS_REQ")
+	}
+	var ASRep messages.ASRep
+
+	rb, err := cl.sendToKDC(b, realm)
+	if err != nil {
+		if e, ok := err.(messages.KRBError); ok {
+			switch e.ErrorCode {
+			case errorcode.KDC_ERR_PREAUTH_REQUIRED, errorcode.KDC_ERR_PREAUTH_FAILED:
+				// From now on assume this client will need to do this pre-auth and set the PAData
+				cl.settings.assumePreAuthentication = true
+				err = setPAData(cl, &e, &ASReq)
+				if err != nil {
+					return messages.ASRep{}, krberror.Errorf(err, krberror.KRBMsgError, "AS Exchange Error: failed setting AS_REQ PAData for pre-authentication required")
+				}
+				b, err := ASReq.Marshal()
+				if err != nil {
+					return messages.ASRep{}, krberror.Errorf(err, krberror.EncodingError, "AS Exchange Error: failed marshaling AS_REQ with PAData")
+				}
+				rb, err = cl.sendToKDC(b, realm)
+				if err != nil {
+					if _, ok := err.(messages.KRBError); ok {
+						return messages.ASRep{}, krberror.Errorf(err, krberror.KDCError, "AS Exchange Error: kerberos error response from KDC")
+					}
+					return messages.ASRep{}, krberror.Errorf(err, krberror.NetworkingError, "AS Exchange Error: failed sending AS_REQ to KDC")
+				}
+			case errorcode.KDC_ERR_WRONG_REALM:
+				// Client referral https://tools.ietf.org/html/rfc6806.html#section-7
+				if referral > 5 {
+					return messages.ASRep{}, krberror.Errorf(err, krberror.KRBMsgError, "maximum number of client referrals exceeded")
+				}
+				referral++
+				return cl.ASExchange(e.CRealm, ASReq, referral)
+			default:
+				return messages.ASRep{}, krberror.Errorf(err, krberror.KDCError, "AS Exchange Error: kerberos error response from KDC")
+			}
+		} else {
+			return messages.ASRep{}, krberror.Errorf(err, krberror.NetworkingError, "AS Exchange Error: failed sending AS_REQ to KDC")
+		}
+	}
+	err = ASRep.Unmarshal(rb)
+	if err != nil {
+		return messages.ASRep{}, krberror.Errorf(err, krberror.EncodingError, "AS Exchange Error: failed to process the AS_REP")
+	}
+	if ok, err := ASRep.Verify(cl.Config, cl.Credentials, ASReq); !ok {
+		return messages.ASRep{}, krberror.Errorf(err, krberror.KRBMsgError, "AS Exchange Error: AS_REP is not valid or client password/keytab incorrect")
+	}
+	return ASRep, nil
+}
+
+// setPAData adds pre-authentication data to the AS_REQ.
+func setPAData(cl *Client, krberr *messages.KRBError, ASReq *messages.ASReq) error {
+	if !cl.settings.DisablePAFXFAST() {
+		pa := types.PAData{PADataType: patype.PA_REQ_ENC_PA_REP}
+		ASReq.PAData = append(ASReq.PAData, pa)
+	}
+	if cl.settings.AssumePreAuthentication() {
+		// Identify the etype to use to encrypt the PA Data
+		var et etype.EType
+		var err error
+		var key types.EncryptionKey
+		if krberr == nil {
+			// This is not in response to an error from the KDC. It is preemptive or renewal
+			// There is no KRB Error that tells us the etype to use
+			etn := cl.settings.preAuthEType // Use the etype that may have previously been negotiated
+			if etn == 0 {
+				etn = int32(cl.Config.LibDefaults.PreferredPreauthTypes[0]) // Resort to config
+			}
+			et, err = crypto.GetEtype(etn)
+			if err != nil {
+				return krberror.Errorf(err, krberror.EncryptingError, "error getting etype for pre-auth encryption")
+			}
+			key, err = cl.Key(et, nil)
+			if err != nil {
+				return krberror.Errorf(err, krberror.EncryptingError, "error getting key from credentials")
+			}
+		} else {
+			// Get the etype to use from the PA data in the KRBError e-data
+			et, err = preAuthEType(krberr)
+			if err != nil {
+				return krberror.Errorf(err, krberror.EncryptingError, "error getting etype for pre-auth encryption")
+			}
+			cl.settings.preAuthEType = et.GetETypeID() // Set the etype that has been defined for potential future use
+			key, err = cl.Key(et, krberr)
+			if err != nil {
+				return krberror.Errorf(err, krberror.EncryptingError, "error getting key from credentials")
+			}
+		}
+		// Generate the PA data
+		paTSb, err := types.GetPAEncTSEncAsnMarshalled()
+		if err != nil {
+			return krberror.Errorf(err, krberror.KRBMsgError, "error creating PAEncTSEnc for Pre-Authentication")
+		}
+		//TODO (theme: KVNO from keytab) the kvno should not be hard coded to 1 as this hampers troubleshooting.
+		paEncTS, err := crypto.GetEncryptedData(paTSb, key, keyusage.AS_REQ_PA_ENC_TIMESTAMP, 1)
+		if err != nil {
+			return krberror.Errorf(err, krberror.EncryptingError, "error encrypting pre-authentication timestamp")
+		}
+		pb, err := paEncTS.Marshal()
+		if err != nil {
+			return krberror.Errorf(err, krberror.EncodingError, "error marshaling the PAEncTSEnc encrypted data")
+		}
+		pa := types.PAData{
+			PADataType:  patype.PA_ENC_TIMESTAMP,
+			PADataValue: pb,
+		}
+		// Look for and delete any exiting patype.PA_ENC_TIMESTAMP
+		for i, pa := range ASReq.PAData {
+			if pa.PADataType == patype.PA_ENC_TIMESTAMP {
+				ASReq.PAData[i] = ASReq.PAData[len(ASReq.PAData)-1]
+				ASReq.PAData = ASReq.PAData[:len(ASReq.PAData)-1]
+			}
+		}
+		ASReq.PAData = append(ASReq.PAData, pa)
+	}
+	return nil
+}
+
+// preAuthEType establishes what encryption type to use for pre-authentication from the KRBError returned from the KDC.
+func preAuthEType(krberr *messages.KRBError) (etype etype.EType, err error) {
+	//The preferred ordering of the "hint" pre-authentication data that
+	//affect client key selection is: ETYPE-INFO2, followed by ETYPE-INFO,
+	//followed by PW-SALT.
+	//A KDC SHOULD NOT send PA-PW-SALT when issuing a KRB-ERROR message
+	//that requests additional pre-authentication.  Implementation note:
+	//Some KDC implementations issue an erroneous PA-PW-SALT when issuing a
+	//KRB-ERROR message that requests additional pre-authentication.
+	//Therefore, clients SHOULD ignore a PA-PW-SALT accompanying a
+	//KRB-ERROR message that requests additional pre-authentication.
+	var etypeID int32
+	var pas types.PADataSequence
+	e := pas.Unmarshal(krberr.EData)
+	if e != nil {
+		err = krberror.Errorf(e, krberror.EncodingError, "error unmashalling KRBError data")
+		return
+	}
+	for _, pa := range pas {
+		switch pa.PADataType {
+		case patype.PA_ETYPE_INFO2:
+			info, e := pa.GetETypeInfo2()
+			if e != nil {
+				err = krberror.Errorf(e, krberror.EncodingError, "error unmashalling ETYPE-INFO2 data")
+				return
+			}
+			etypeID = info[0].EType
+			break
+		case patype.PA_ETYPE_INFO:
+			info, e := pa.GetETypeInfo()
+			if e != nil {
+				err = krberror.Errorf(e, krberror.EncodingError, "error unmashalling ETYPE-INFO data")
+				return
+			}
+			etypeID = info[0].EType
+		}
+	}
+	etype, e = crypto.GetEtype(etypeID)
+	if e != nil {
+		err = krberror.Errorf(e, krberror.EncryptingError, "error creating etype")
+		return
+	}
+	return etype, nil
+}
diff --git a/vendor/gopkg.in/jcmturner/gokrb5.v7/client/TGSExchange.go b/vendor/gopkg.in/jcmturner/gokrb5.v7/client/TGSExchange.go
new file mode 100644
index 0000000..93ff1db
--- /dev/null
+++ b/vendor/gopkg.in/jcmturner/gokrb5.v7/client/TGSExchange.go
@@ -0,0 +1,103 @@
+package client
+
+import (
+	"gopkg.in/jcmturner/gokrb5.v7/iana/flags"
+	"gopkg.in/jcmturner/gokrb5.v7/iana/nametype"
+	"gopkg.in/jcmturner/gokrb5.v7/krberror"
+	"gopkg.in/jcmturner/gokrb5.v7/messages"
+	"gopkg.in/jcmturner/gokrb5.v7/types"
+)
+
+// TGSREQGenerateAndExchange generates the TGS_REQ and performs a TGS exchange to retrieve a ticket to the specified SPN.
+func (cl *Client) TGSREQGenerateAndExchange(spn types.PrincipalName, kdcRealm string, tgt messages.Ticket, sessionKey types.EncryptionKey, renewal bool) (tgsReq messages.TGSReq, tgsRep messages.TGSRep, err error) {
+	tgsReq, err = messages.NewTGSReq(cl.Credentials.CName(), kdcRealm, cl.Config, tgt, sessionKey, spn, renewal)
+	if err != nil {
+		return tgsReq, tgsRep, krberror.Errorf(err, krberror.KRBMsgError, "TGS Exchange Error: failed to generate a new TGS_REQ")
+	}
+	return cl.TGSExchange(tgsReq, kdcRealm, tgsRep.Ticket, sessionKey, 0)
+}
+
+// TGSExchange exchanges the provided TGS_REQ with the KDC to retrieve a TGS_REP.
+// Referrals are automatically handled.
+// The client's cache is updated with the ticket received.
+func (cl *Client) TGSExchange(tgsReq messages.TGSReq, kdcRealm string, tgt messages.Ticket, sessionKey types.EncryptionKey, referral int) (messages.TGSReq, messages.TGSRep, error) {
+	var tgsRep messages.TGSRep
+	b, err := tgsReq.Marshal()
+	if err != nil {
+		return tgsReq, tgsRep, krberror.Errorf(err, krberror.EncodingError, "TGS Exchange Error: failed to marshal TGS_REQ")
+	}
+	r, err := cl.sendToKDC(b, kdcRealm)
+	if err != nil {
+		if _, ok := err.(messages.KRBError); ok {
+			return tgsReq, tgsRep, krberror.Errorf(err, krberror.KDCError, "TGS Exchange Error: kerberos error response from KDC when requesting for %s", tgsReq.ReqBody.SName.PrincipalNameString())
+		}
+		return tgsReq, tgsRep, krberror.Errorf(err, krberror.NetworkingError, "TGS Exchange Error: issue sending TGS_REQ to KDC")
+	}
+	err = tgsRep.Unmarshal(r)
+	if err != nil {
+		return tgsReq, tgsRep, krberror.Errorf(err, krberror.EncodingError, "TGS Exchange Error: failed to process the TGS_REP")
+	}
+	err = tgsRep.DecryptEncPart(sessionKey)
+	if err != nil {
+		return tgsReq, tgsRep, krberror.Errorf(err, krberror.EncodingError, "TGS Exchange Error: failed to process the TGS_REP")
+	}
+	if ok, err := tgsRep.Verify(cl.Config, tgsReq); !ok {
+		return tgsReq, tgsRep, krberror.Errorf(err, krberror.EncodingError, "TGS Exchange Error: TGS_REP is not valid")
+	}
+
+	if tgsRep.Ticket.SName.NameString[0] == "krbtgt" && !tgsRep.Ticket.SName.Equal(tgsReq.ReqBody.SName) {
+		if referral > 5 {
+			return tgsReq, tgsRep, krberror.Errorf(err, krberror.KRBMsgError, "TGS Exchange Error: maximum number of referrals exceeded")
+		}
+		// Server referral https://tools.ietf.org/html/rfc6806.html#section-8
+		// The TGS Rep contains a TGT for another domain as the service resides in that domain.
+		cl.addSession(tgsRep.Ticket, tgsRep.DecryptedEncPart)
+		realm := tgsRep.Ticket.SName.NameString[len(tgsRep.Ticket.SName.NameString)-1]
+		referral++
+		if types.IsFlagSet(&tgsReq.ReqBody.KDCOptions, flags.EncTktInSkey) && len(tgsReq.ReqBody.AdditionalTickets) > 0 {
+			tgsReq, err = messages.NewUser2UserTGSReq(cl.Credentials.CName(), kdcRealm, cl.Config, tgt, sessionKey, tgsReq.ReqBody.SName, tgsReq.Renewal, tgsReq.ReqBody.AdditionalTickets[0])
+			if err != nil {
+				return tgsReq, tgsRep, err
+			}
+		}
+		tgsReq, err = messages.NewTGSReq(cl.Credentials.CName(), realm, cl.Config, tgsRep.Ticket, tgsRep.DecryptedEncPart.Key, tgsReq.ReqBody.SName, tgsReq.Renewal)
+		if err != nil {
+			return tgsReq, tgsRep, err
+		}
+		return cl.TGSExchange(tgsReq, realm, tgsRep.Ticket, tgsRep.DecryptedEncPart.Key, referral)
+	}
+	cl.cache.addEntry(
+		tgsRep.Ticket,
+		tgsRep.DecryptedEncPart.AuthTime,
+		tgsRep.DecryptedEncPart.StartTime,
+		tgsRep.DecryptedEncPart.EndTime,
+		tgsRep.DecryptedEncPart.RenewTill,
+		tgsRep.DecryptedEncPart.Key,
+	)
+	cl.Log("ticket added to cache for %s (EndTime: %v)", tgsRep.Ticket.SName.PrincipalNameString(), tgsRep.DecryptedEncPart.EndTime)
+	return tgsReq, tgsRep, err
+}
+
+// GetServiceTicket makes a request to get a service ticket for the SPN specified
+// SPN format: <SERVICE>/<FQDN> Eg. HTTP/www.example.com
+// The ticket will be added to the client's ticket cache
+func (cl *Client) GetServiceTicket(spn string) (messages.Ticket, types.EncryptionKey, error) {
+	var tkt messages.Ticket
+	var skey types.EncryptionKey
+	if tkt, skey, ok := cl.GetCachedTicket(spn); ok {
+		// Already a valid ticket in the cache
+		return tkt, skey, nil
+	}
+	princ := types.NewPrincipalName(nametype.KRB_NT_PRINCIPAL, spn)
+	realm := cl.Config.ResolveRealm(princ.NameString[len(princ.NameString)-1])
+
+	tgt, skey, err := cl.sessionTGT(realm)
+	if err != nil {
+		return tkt, skey, err
+	}
+	_, tgsRep, err := cl.TGSREQGenerateAndExchange(princ, realm, tgt, skey, false)
+	if err != nil {
+		return tkt, skey, err
+	}
+	return tgsRep.Ticket, tgsRep.DecryptedEncPart.Key, nil
+}
diff --git a/vendor/gopkg.in/jcmturner/gokrb5.v7/client/cache.go b/vendor/gopkg.in/jcmturner/gokrb5.v7/client/cache.go
new file mode 100644
index 0000000..07b4a01
--- /dev/null
+++ b/vendor/gopkg.in/jcmturner/gokrb5.v7/client/cache.go
@@ -0,0 +1,110 @@
+package client
+
+import (
+	"errors"
+	"sync"
+	"time"
+
+	"gopkg.in/jcmturner/gokrb5.v7/messages"
+	"gopkg.in/jcmturner/gokrb5.v7/types"
+)
+
+// Cache for service tickets held by the client.
+type Cache struct {
+	Entries map[string]CacheEntry
+	mux     sync.RWMutex
+}
+
+// CacheEntry holds details for a cache entry.
+type CacheEntry struct {
+	Ticket     messages.Ticket
+	AuthTime   time.Time
+	StartTime  time.Time
+	EndTime    time.Time
+	RenewTill  time.Time
+	SessionKey types.EncryptionKey
+}
+
+// NewCache creates a new client ticket cache instance.
+func NewCache() *Cache {
+	return &Cache{
+		Entries: map[string]CacheEntry{},
+	}
+}
+
+// getEntry returns a cache entry that matches the SPN.
+func (c *Cache) getEntry(spn string) (CacheEntry, bool) {
+	c.mux.RLock()
+	defer c.mux.RUnlock()
+	e, ok := (*c).Entries[spn]
+	return e, ok
+}
+
+// addEntry adds a ticket to the cache.
+func (c *Cache) addEntry(tkt messages.Ticket, authTime, startTime, endTime, renewTill time.Time, sessionKey types.EncryptionKey) CacheEntry {
+	spn := tkt.SName.PrincipalNameString()
+	c.mux.Lock()
+	defer c.mux.Unlock()
+	(*c).Entries[spn] = CacheEntry{
+		Ticket:     tkt,
+		AuthTime:   authTime,
+		StartTime:  startTime,
+		EndTime:    endTime,
+		RenewTill:  renewTill,
+		SessionKey: sessionKey,
+	}
+	return c.Entries[spn]
+}
+
+// clear deletes all the cache entries
+func (c *Cache) clear() {
+	c.mux.Lock()
+	defer c.mux.Unlock()
+	for k := range c.Entries {
+		delete(c.Entries, k)
+	}
+}
+
+// RemoveEntry removes the cache entry for the defined SPN.
+func (c *Cache) RemoveEntry(spn string) {
+	c.mux.Lock()
+	defer c.mux.Unlock()
+	delete(c.Entries, spn)
+}
+
+// GetCachedTicket returns a ticket from the cache for the SPN.
+// Only a ticket that is currently valid will be returned.
+func (cl *Client) GetCachedTicket(spn string) (messages.Ticket, types.EncryptionKey, bool) {
+	if e, ok := cl.cache.getEntry(spn); ok {
+		//If within time window of ticket return it
+		if time.Now().UTC().After(e.StartTime) && time.Now().UTC().Before(e.EndTime) {
+			cl.Log("ticket received from cache for %s", spn)
+			return e.Ticket, e.SessionKey, true
+		} else if time.Now().UTC().Before(e.RenewTill) {
+			e, err := cl.renewTicket(e)
+			if err != nil {
+				return e.Ticket, e.SessionKey, false
+			}
+			return e.Ticket, e.SessionKey, true
+		}
+	}
+	var tkt messages.Ticket
+	var key types.EncryptionKey
+	return tkt, key, false
+}
+
+// renewTicket renews a cache entry ticket.
+// To renew from outside the client package use GetCachedTicket
+func (cl *Client) renewTicket(e CacheEntry) (CacheEntry, error) {
+	spn := e.Ticket.SName
+	_, _, err := cl.TGSREQGenerateAndExchange(spn, e.Ticket.Realm, e.Ticket, e.SessionKey, true)
+	if err != nil {
+		return e, err
+	}
+	e, ok := cl.cache.getEntry(e.Ticket.SName.PrincipalNameString())
+	if !ok {
+		return e, errors.New("ticket was not added to cache")
+	}
+	cl.Log("ticket renewed for %s (EndTime: %v)", spn.PrincipalNameString(), e.EndTime)
+	return e, nil
+}
diff --git a/vendor/gopkg.in/jcmturner/gokrb5.v7/client/client.go b/vendor/gopkg.in/jcmturner/gokrb5.v7/client/client.go
new file mode 100644
index 0000000..cc93174
--- /dev/null
+++ b/vendor/gopkg.in/jcmturner/gokrb5.v7/client/client.go
@@ -0,0 +1,241 @@
+// Package client provides a client library and methods for Kerberos 5 authentication.
+package client
+
+import (
+	"errors"
+	"fmt"
+	"time"
+
+	"gopkg.in/jcmturner/gokrb5.v7/config"
+	"gopkg.in/jcmturner/gokrb5.v7/credentials"
+	"gopkg.in/jcmturner/gokrb5.v7/crypto"
+	"gopkg.in/jcmturner/gokrb5.v7/crypto/etype"
+	"gopkg.in/jcmturner/gokrb5.v7/iana/errorcode"
+	"gopkg.in/jcmturner/gokrb5.v7/iana/nametype"
+	"gopkg.in/jcmturner/gokrb5.v7/keytab"
+	"gopkg.in/jcmturner/gokrb5.v7/krberror"
+	"gopkg.in/jcmturner/gokrb5.v7/messages"
+	"gopkg.in/jcmturner/gokrb5.v7/types"
+)
+
+// Client side configuration and state.
+type Client struct {
+	Credentials *credentials.Credentials
+	Config      *config.Config
+	settings    *Settings
+	sessions    *sessions
+	cache       *Cache
+}
+
+// NewClientWithPassword creates a new client from a password credential.
+// Set the realm to empty string to use the default realm from config.
+func NewClientWithPassword(username, realm, password string, krb5conf *config.Config, settings ...func(*Settings)) *Client {
+	creds := credentials.New(username, realm)
+	return &Client{
+		Credentials: creds.WithPassword(password),
+		Config:      krb5conf,
+		settings:    NewSettings(settings...),
+		sessions: &sessions{
+			Entries: make(map[string]*session),
+		},
+		cache: NewCache(),
+	}
+}
+
+// NewClientWithKeytab creates a new client from a keytab credential.
+func NewClientWithKeytab(username, realm string, kt *keytab.Keytab, krb5conf *config.Config, settings ...func(*Settings)) *Client {
+	creds := credentials.New(username, realm)
+	return &Client{
+		Credentials: creds.WithKeytab(kt),
+		Config:      krb5conf,
+		settings:    NewSettings(settings...),
+		sessions: &sessions{
+			Entries: make(map[string]*session),
+		},
+		cache: NewCache(),
+	}
+}
+
+// NewClientFromCCache create a client from a populated client cache.
+//
+// WARNING: A client created from CCache does not automatically renew TGTs and a failure will occur after the TGT expires.
+func NewClientFromCCache(c *credentials.CCache, krb5conf *config.Config, settings ...func(*Settings)) (*Client, error) {
+	cl := &Client{
+		Credentials: c.GetClientCredentials(),
+		Config:      krb5conf,
+		settings:    NewSettings(settings...),
+		sessions: &sessions{
+			Entries: make(map[string]*session),
+		},
+		cache: NewCache(),
+	}
+	spn := types.PrincipalName{
+		NameType:   nametype.KRB_NT_SRV_INST,
+		NameString: []string{"krbtgt", c.DefaultPrincipal.Realm},
+	}
+	cred, ok := c.GetEntry(spn)
+	if !ok {
+		return cl, errors.New("TGT not found in CCache")
+	}
+	var tgt messages.Ticket
+	err := tgt.Unmarshal(cred.Ticket)
+	if err != nil {
+		return cl, fmt.Errorf("TGT bytes in cache are not valid: %v", err)
+	}
+	cl.sessions.Entries[c.DefaultPrincipal.Realm] = &session{
+		realm:      c.DefaultPrincipal.Realm,
+		authTime:   cred.AuthTime,
+		endTime:    cred.EndTime,
+		renewTill:  cred.RenewTill,
+		tgt:        tgt,
+		sessionKey: cred.Key,
+	}
+	for _, cred := range c.GetEntries() {
+		var tkt messages.Ticket
+		err = tkt.Unmarshal(cred.Ticket)
+		if err != nil {
+			return cl, fmt.Errorf("cache entry ticket bytes are not valid: %v", err)
+		}
+		cl.cache.addEntry(
+			tkt,
+			cred.AuthTime,
+			cred.StartTime,
+			cred.EndTime,
+			cred.RenewTill,
+			cred.Key,
+		)
+	}
+	return cl, nil
+}
+
+// Key returns the client's encryption key for the specified encryption type.
+// The key can be retrieved either from the keytab or generated from the client's password.
+// If the client has both a keytab and a password defined the keytab is favoured as the source for the key
+// A KRBError can be passed in the event the KDC returns one of type KDC_ERR_PREAUTH_REQUIRED and is required to derive
+// the key for pre-authentication from the client's password. If a KRBError is not available, pass nil to this argument.
+func (cl *Client) Key(etype etype.EType, krberr *messages.KRBError) (types.EncryptionKey, error) {
+	if cl.Credentials.HasKeytab() && etype != nil {
+		return cl.Credentials.Keytab().GetEncryptionKey(cl.Credentials.CName(), cl.Credentials.Domain(), 0, etype.GetETypeID())
+	} else if cl.Credentials.HasPassword() {
+		if krberr != nil && krberr.ErrorCode == errorcode.KDC_ERR_PREAUTH_REQUIRED {
+			var pas types.PADataSequence
+			err := pas.Unmarshal(krberr.EData)
+			if err != nil {
+				return types.EncryptionKey{}, fmt.Errorf("could not get PAData from KRBError to generate key from password: %v", err)
+			}
+			key, _, err := crypto.GetKeyFromPassword(cl.Credentials.Password(), krberr.CName, krberr.CRealm, etype.GetETypeID(), pas)
+			return key, err
+		}
+		key, _, err := crypto.GetKeyFromPassword(cl.Credentials.Password(), cl.Credentials.CName(), cl.Credentials.Domain(), etype.GetETypeID(), types.PADataSequence{})
+		return key, err
+	}
+	return types.EncryptionKey{}, errors.New("credential has neither keytab or password to generate key")
+}
+
+// IsConfigured indicates if the client has the values required set.
+func (cl *Client) IsConfigured() (bool, error) {
+	if cl.Credentials.UserName() == "" {
+		return false, errors.New("client does not have a username")
+	}
+	if cl.Credentials.Domain() == "" {
+		return false, errors.New("client does not have a define realm")
+	}
+	// Client needs to have either a password, keytab or a session already (later when loading from CCache)
+	if !cl.Credentials.HasPassword() && !cl.Credentials.HasKeytab() {
+		authTime, _, _, _, err := cl.sessionTimes(cl.Credentials.Domain())
+		if err != nil || authTime.IsZero() {
+			return false, errors.New("client has neither a keytab nor a password set and no session")
+		}
+	}
+	if !cl.Config.LibDefaults.DNSLookupKDC {
+		for _, r := range cl.Config.Realms {
+			if r.Realm == cl.Credentials.Domain() {
+				if len(r.KDC) > 0 {
+					return true, nil
+				}
+				return false, errors.New("client krb5 config does not have any defined KDCs for the default realm")
+			}
+		}
+	}
+	return true, nil
+}
+
+// Login the client with the KDC via an AS exchange.
+func (cl *Client) Login() error {
+	if ok, err := cl.IsConfigured(); !ok {
+		return err
+	}
+	if !cl.Credentials.HasPassword() && !cl.Credentials.HasKeytab() {
+		_, endTime, _, _, err := cl.sessionTimes(cl.Credentials.Domain())
+		if err != nil {
+			return krberror.Errorf(err, krberror.KRBMsgError, "no user credentials available and error getting any existing session")
+		}
+		if time.Now().UTC().After(endTime) {
+			return krberror.NewKrberror(krberror.KRBMsgError, "cannot login, no user credentials available and no valid existing session")
+		}
+		// no credentials but there is a session with tgt already
+		return nil
+	}
+	ASReq, err := messages.NewASReqForTGT(cl.Credentials.Domain(), cl.Config, cl.Credentials.CName())
+	if err != nil {
+		return krberror.Errorf(err, krberror.KRBMsgError, "error generating new AS_REQ")
+	}
+	ASRep, err := cl.ASExchange(cl.Credentials.Domain(), ASReq, 0)
+	if err != nil {
+		return err
+	}
+	cl.addSession(ASRep.Ticket, ASRep.DecryptedEncPart)
+	return nil
+}
+
+// AffirmLogin will only perform an AS exchange with the KDC if the client does not already have a TGT.
+func (cl *Client) AffirmLogin() error {
+	_, endTime, _, _, err := cl.sessionTimes(cl.Credentials.Domain())
+	if err != nil || time.Now().UTC().After(endTime) {
+		err := cl.Login()
+		if err != nil {
+			return fmt.Errorf("could not get valid TGT for client's realm: %v", err)
+		}
+	}
+	return nil
+}
+
+// realmLogin obtains or renews a TGT and establishes a session for the realm specified.
+func (cl *Client) realmLogin(realm string) error {
+	if realm == cl.Credentials.Domain() {
+		return cl.Login()
+	}
+	_, endTime, _, _, err := cl.sessionTimes(cl.Credentials.Domain())
+	if err != nil || time.Now().UTC().After(endTime) {
+		err := cl.Login()
+		if err != nil {
+			return fmt.Errorf("could not get valid TGT for client's realm: %v", err)
+		}
+	}
+	tgt, skey, err := cl.sessionTGT(cl.Credentials.Domain())
+	if err != nil {
+		return err
+	}
+
+	spn := types.PrincipalName{
+		NameType:   nametype.KRB_NT_SRV_INST,
+		NameString: []string{"krbtgt", realm},
+	}
+
+	_, tgsRep, err := cl.TGSREQGenerateAndExchange(spn, cl.Credentials.Domain(), tgt, skey, false)
+	if err != nil {
+		return err
+	}
+	cl.addSession(tgsRep.Ticket, tgsRep.DecryptedEncPart)
+
+	return nil
+}
+
+// Destroy stops the auto-renewal of all sessions and removes the sessions and cache entries from the client.
+func (cl *Client) Destroy() {
+	creds := credentials.New("", "")
+	cl.sessions.destroy()
+	cl.cache.clear()
+	cl.Credentials = creds
+	cl.Log("client destroyed")
+}
diff --git a/vendor/gopkg.in/jcmturner/gokrb5.v7/client/network.go b/vendor/gopkg.in/jcmturner/gokrb5.v7/client/network.go
new file mode 100644
index 0000000..493fb2f
--- /dev/null
+++ b/vendor/gopkg.in/jcmturner/gokrb5.v7/client/network.go
@@ -0,0 +1,224 @@
+package client
+
+import (
+	"bytes"
+	"encoding/binary"
+	"errors"
+	"fmt"
+	"io"
+	"net"
+	"time"
+
+	"gopkg.in/jcmturner/gokrb5.v7/iana/errorcode"
+	"gopkg.in/jcmturner/gokrb5.v7/messages"
+)
+
+// SendToKDC performs network actions to send data to the KDC.
+func (cl *Client) sendToKDC(b []byte, realm string) ([]byte, error) {
+	var rb []byte
+	if cl.Config.LibDefaults.UDPPreferenceLimit == 1 {
+		//1 means we should always use TCP
+		rb, errtcp := cl.sendKDCTCP(realm, b)
+		if errtcp != nil {
+			if e, ok := errtcp.(messages.KRBError); ok {
+				return rb, e
+			}
+			return rb, fmt.Errorf("communication error with KDC via TCP: %v", errtcp)
+		}
+		return rb, nil
+	}
+	if len(b) <= cl.Config.LibDefaults.UDPPreferenceLimit {
+		//Try UDP first, TCP second
+		rb, errudp := cl.sendKDCUDP(realm, b)
+		if errudp != nil {
+			if e, ok := errudp.(messages.KRBError); ok && e.ErrorCode != errorcode.KRB_ERR_RESPONSE_TOO_BIG {
+				// Got a KRBError from KDC
+				// If this is not a KRB_ERR_RESPONSE_TOO_BIG we will return immediately otherwise will try TCP.
+				return rb, e
+			}
+			// Try TCP
+			r, errtcp := cl.sendKDCTCP(realm, b)
+			if errtcp != nil {
+				if e, ok := errtcp.(messages.KRBError); ok {
+					// Got a KRBError
+					return r, e
+				}
+				return r, fmt.Errorf("failed to communicate with KDC. Attempts made with UDP (%v) and then TCP (%v)", errudp, errtcp)
+			}
+			rb = r
+		}
+		return rb, nil
+	}
+	//Try TCP first, UDP second
+	rb, errtcp := cl.sendKDCTCP(realm, b)
+	if errtcp != nil {
+		if e, ok := errtcp.(messages.KRBError); ok {
+			// Got a KRBError from KDC so returning and not trying UDP.
+			return rb, e
+		}
+		rb, errudp := cl.sendKDCUDP(realm, b)
+		if errudp != nil {
+			if e, ok := errudp.(messages.KRBError); ok {
+				// Got a KRBError
+				return rb, e
+			}
+			return rb, fmt.Errorf("failed to communicate with KDC. Attempts made with TCP (%v) and then UDP (%v)", errtcp, errudp)
+		}
+	}
+	return rb, nil
+}
+
+// dialKDCTCP establishes a UDP connection to a KDC.
+func dialKDCUDP(count int, kdcs map[int]string) (*net.UDPConn, error) {
+	i := 1
+	for i <= count {
+		udpAddr, err := net.ResolveUDPAddr("udp", kdcs[i])
+		if err != nil {
+			return nil, fmt.Errorf("error resolving KDC address: %v", err)
+		}
+
+		conn, err := net.DialTimeout("udp", udpAddr.String(), 5*time.Second)
+		if err == nil {
+			if err := conn.SetDeadline(time.Now().Add(5 * time.Second)); err != nil {
+				return nil, err
+			}
+			// conn is guaranteed to be a UDPConn
+			return conn.(*net.UDPConn), nil
+		}
+		i++
+	}
+	return nil, errors.New("error in getting a UDP connection to any of the KDCs")
+}
+
+// dialKDCTCP establishes a TCP connection to a KDC.
+func dialKDCTCP(count int, kdcs map[int]string) (*net.TCPConn, error) {
+	i := 1
+	for i <= count {
+		tcpAddr, err := net.ResolveTCPAddr("tcp", kdcs[i])
+		if err != nil {
+			return nil, fmt.Errorf("error resolving KDC address: %v", err)
+		}
+
+		conn, err := net.DialTimeout("tcp", tcpAddr.String(), 5*time.Second)
+		if err == nil {
+			if err := conn.SetDeadline(time.Now().Add(5 * time.Second)); err != nil {
+				return nil, err
+			}
+			// conn is guaranteed to be a TCPConn
+			return conn.(*net.TCPConn), nil
+		}
+		i++
+	}
+	return nil, errors.New("error in getting a TCP connection to any of the KDCs")
+}
+
+// sendKDCUDP sends bytes to the KDC via UDP.
+func (cl *Client) sendKDCUDP(realm string, b []byte) ([]byte, error) {
+	var r []byte
+	count, kdcs, err := cl.Config.GetKDCs(realm, false)
+	if err != nil {
+		return r, err
+	}
+	conn, err := dialKDCUDP(count, kdcs)
+	if err != nil {
+		return r, err
+	}
+	r, err = cl.sendUDP(conn, b)
+	if err != nil {
+		return r, err
+	}
+	return checkForKRBError(r)
+}
+
+// sendKDCTCP sends bytes to the KDC via TCP.
+func (cl *Client) sendKDCTCP(realm string, b []byte) ([]byte, error) {
+	var r []byte
+	count, kdcs, err := cl.Config.GetKDCs(realm, true)
+	if err != nil {
+		return r, err
+	}
+	conn, err := dialKDCTCP(count, kdcs)
+	if err != nil {
+		return r, err
+	}
+	rb, err := cl.sendTCP(conn, b)
+	if err != nil {
+		return r, err
+	}
+	return checkForKRBError(rb)
+}
+
+// sendUDP sends bytes to connection over UDP.
+func (cl *Client) sendUDP(conn *net.UDPConn, b []byte) ([]byte, error) {
+	var r []byte
+	defer conn.Close()
+	_, err := conn.Write(b)
+	if err != nil {
+		return r, fmt.Errorf("error sending to (%s): %v", conn.RemoteAddr().String(), err)
+	}
+	udpbuf := make([]byte, 4096)
+	n, _, err := conn.ReadFrom(udpbuf)
+	r = udpbuf[:n]
+	if err != nil {
+		return r, fmt.Errorf("sending over UDP failed to %s: %v", conn.RemoteAddr().String(), err)
+	}
+	if len(r) < 1 {
+		return r, fmt.Errorf("no response data from %s", conn.RemoteAddr().String())
+	}
+	return r, nil
+}
+
+// sendTCP sends bytes to connection over TCP.
+func (cl *Client) sendTCP(conn *net.TCPConn, b []byte) ([]byte, error) {
+	defer conn.Close()
+	var r []byte
+	/*
+		RFC https://tools.ietf.org/html/rfc4120#section-7.2.2
+		Each request (KRB_KDC_REQ) and response (KRB_KDC_REP or KRB_ERROR)
+		sent over the TCP stream is preceded by the length of the request as
+		4 octets in network byte order.  The high bit of the length is
+		reserved for future expansion and MUST currently be set to zero.  If
+		a KDC that does not understand how to interpret a set high bit of the
+		length encoding receives a request with the high order bit of the
+		length set, it MUST return a KRB-ERROR message with the error
+		KRB_ERR_FIELD_TOOLONG and MUST close the TCP stream.
+		NB: network byte order == big endian
+	*/
+	var buf bytes.Buffer
+	err := binary.Write(&buf, binary.BigEndian, uint32(len(b)))
+	if err != nil {
+		return r, err
+	}
+	b = append(buf.Bytes(), b...)
+
+	_, err = conn.Write(b)
+	if err != nil {
+		return r, fmt.Errorf("error sending to KDC (%s): %v", conn.RemoteAddr().String(), err)
+	}
+
+	sh := make([]byte, 4, 4)
+	_, err = conn.Read(sh)
+	if err != nil {
+		return r, fmt.Errorf("error reading response size header: %v", err)
+	}
+	s := binary.BigEndian.Uint32(sh)
+
+	rb := make([]byte, s, s)
+	_, err = io.ReadFull(conn, rb)
+	if err != nil {
+		return r, fmt.Errorf("error reading response: %v", err)
+	}
+	if len(rb) < 1 {
+		return r, fmt.Errorf("no response data from KDC %s", conn.RemoteAddr().String())
+	}
+	return rb, nil
+}
+
+// checkForKRBError checks if the response bytes from the KDC are a KRBError.
+func checkForKRBError(b []byte) ([]byte, error) {
+	var KRBErr messages.KRBError
+	if err := KRBErr.Unmarshal(b); err == nil {
+		return b, KRBErr
+	}
+	return b, nil
+}
diff --git a/vendor/gopkg.in/jcmturner/gokrb5.v7/client/passwd.go b/vendor/gopkg.in/jcmturner/gokrb5.v7/client/passwd.go
new file mode 100644
index 0000000..da838ed
--- /dev/null
+++ b/vendor/gopkg.in/jcmturner/gokrb5.v7/client/passwd.go
@@ -0,0 +1,95 @@
+package client
+
+import (
+	"fmt"
+	"net"
+
+	"gopkg.in/jcmturner/gokrb5.v7/kadmin"
+	"gopkg.in/jcmturner/gokrb5.v7/messages"
+)
+
+// Kpasswd server response codes.
+const (
+	KRB5_KPASSWD_SUCCESS             = 0
+	KRB5_KPASSWD_MALFORMED           = 1
+	KRB5_KPASSWD_HARDERROR           = 2
+	KRB5_KPASSWD_AUTHERROR           = 3
+	KRB5_KPASSWD_SOFTERROR           = 4
+	KRB5_KPASSWD_ACCESSDENIED        = 5
+	KRB5_KPASSWD_BAD_VERSION         = 6
+	KRB5_KPASSWD_INITIAL_FLAG_NEEDED = 7
+)
+
+// ChangePasswd changes the password of the client to the value provided.
+func (cl *Client) ChangePasswd(newPasswd string) (bool, error) {
+	ASReq, err := messages.NewASReqForChgPasswd(cl.Credentials.Domain(), cl.Config, cl.Credentials.CName())
+	if err != nil {
+		return false, err
+	}
+	ASRep, err := cl.ASExchange(cl.Credentials.Domain(), ASReq, 0)
+	if err != nil {
+		return false, err
+	}
+
+	msg, key, err := kadmin.ChangePasswdMsg(cl.Credentials.CName(), cl.Credentials.Domain(), newPasswd, ASRep.Ticket, ASRep.DecryptedEncPart.Key)
+	if err != nil {
+		return false, err
+	}
+	r, err := cl.sendToKPasswd(msg)
+	if err != nil {
+		return false, err
+	}
+	err = r.Decrypt(key)
+	if err != nil {
+		return false, err
+	}
+	if r.ResultCode != KRB5_KPASSWD_SUCCESS {
+		return false, fmt.Errorf("error response from kadmin: code: %d; result: %s; krberror: %v", r.ResultCode, r.Result, r.KRBError)
+	}
+	cl.Credentials.WithPassword(newPasswd)
+	return true, nil
+}
+
+func (cl *Client) sendToKPasswd(msg kadmin.Request) (r kadmin.Reply, err error) {
+	_, kps, err := cl.Config.GetKpasswdServers(cl.Credentials.Domain(), true)
+	if err != nil {
+		return
+	}
+	addr := kps[1]
+	b, err := msg.Marshal()
+	if err != nil {
+		return
+	}
+	if len(b) <= cl.Config.LibDefaults.UDPPreferenceLimit {
+		return cl.sendKPasswdUDP(b, addr)
+	}
+	return cl.sendKPasswdTCP(b, addr)
+}
+
+func (cl *Client) sendKPasswdTCP(b []byte, kadmindAddr string) (r kadmin.Reply, err error) {
+	tcpAddr, err := net.ResolveTCPAddr("tcp", kadmindAddr)
+	if err != nil {
+		return
+	}
+	conn, err := net.DialTCP("tcp", nil, tcpAddr)
+	if err != nil {
+		return
+	}
+	rb, err := cl.sendTCP(conn, b)
+	err = r.Unmarshal(rb)
+	return
+}
+
+func (cl *Client) sendKPasswdUDP(b []byte, kadmindAddr string) (r kadmin.Reply, err error) {
+	udpAddr, err := net.ResolveUDPAddr("udp", kadmindAddr)
+	if err != nil {
+		return
+	}
+	conn, err := net.DialUDP("udp", nil, udpAddr)
+	if err != nil {
+		return
+	}
+	rb, err := cl.sendUDP(conn, b)
+	err = r.Unmarshal(rb)
+	return
+}
diff --git a/vendor/gopkg.in/jcmturner/gokrb5.v7/client/session.go b/vendor/gopkg.in/jcmturner/gokrb5.v7/client/session.go
new file mode 100644
index 0000000..ec6c513
--- /dev/null
+++ b/vendor/gopkg.in/jcmturner/gokrb5.v7/client/session.go
@@ -0,0 +1,255 @@
+package client
+
+import (
+	"fmt"
+	"strings"
+	"sync"
+	"time"
+
+	"gopkg.in/jcmturner/gokrb5.v7/iana/nametype"
+	"gopkg.in/jcmturner/gokrb5.v7/krberror"
+	"gopkg.in/jcmturner/gokrb5.v7/messages"
+	"gopkg.in/jcmturner/gokrb5.v7/types"
+)
+
+// sessions hold TGTs and are keyed on the realm name
+type sessions struct {
+	Entries map[string]*session
+	mux     sync.RWMutex
+}
+
+// destroy erases all sessions
+func (s *sessions) destroy() {
+	s.mux.Lock()
+	defer s.mux.Unlock()
+	for k, e := range s.Entries {
+		e.destroy()
+		delete(s.Entries, k)
+	}
+}
+
+// update replaces a session with the one provided or adds it as a new one
+func (s *sessions) update(sess *session) {
+	s.mux.Lock()
+	defer s.mux.Unlock()
+	// if a session already exists for this, cancel its auto renew.
+	if i, ok := s.Entries[sess.realm]; ok {
+		if i != sess {
+			// Session in the sessions cache is not the same as one provided.
+			// Cancel the one in the cache and add this one.
+			i.mux.Lock()
+			defer i.mux.Unlock()
+			i.cancel <- true
+			s.Entries[sess.realm] = sess
+			return
+		}
+	}
+	// No session for this realm was found so just add it
+	s.Entries[sess.realm] = sess
+}
+
+// get returns the session for the realm specified
+func (s *sessions) get(realm string) (*session, bool) {
+	s.mux.RLock()
+	defer s.mux.RUnlock()
+	sess, ok := s.Entries[realm]
+	return sess, ok
+}
+
+// session holds the TGT details for a realm
+type session struct {
+	realm                string
+	authTime             time.Time
+	endTime              time.Time
+	renewTill            time.Time
+	tgt                  messages.Ticket
+	sessionKey           types.EncryptionKey
+	sessionKeyExpiration time.Time
+	cancel               chan bool
+	mux                  sync.RWMutex
+}
+
+// AddSession adds a session for a realm with a TGT to the client's session cache.
+// A goroutine is started to automatically renew the TGT before expiry.
+func (cl *Client) addSession(tgt messages.Ticket, dep messages.EncKDCRepPart) {
+	if strings.ToLower(tgt.SName.NameString[0]) != "krbtgt" {
+		// Not a TGT
+		return
+	}
+	realm := tgt.SName.NameString[len(tgt.SName.NameString)-1]
+	s := &session{
+		realm:                realm,
+		authTime:             dep.AuthTime,
+		endTime:              dep.EndTime,
+		renewTill:            dep.RenewTill,
+		tgt:                  tgt,
+		sessionKey:           dep.Key,
+		sessionKeyExpiration: dep.KeyExpiration,
+	}
+	cl.sessions.update(s)
+	cl.enableAutoSessionRenewal(s)
+	cl.Log("TGT session added for %s (EndTime: %v)", realm, dep.EndTime)
+}
+
+// update overwrites the session details with those from the TGT and decrypted encPart
+func (s *session) update(tgt messages.Ticket, dep messages.EncKDCRepPart) {
+	s.mux.Lock()
+	defer s.mux.Unlock()
+	s.authTime = dep.AuthTime
+	s.endTime = dep.EndTime
+	s.renewTill = dep.RenewTill
+	s.tgt = tgt
+	s.sessionKey = dep.Key
+	s.sessionKeyExpiration = dep.KeyExpiration
+}
+
+// destroy will cancel any auto renewal of the session and set the expiration times to the current time
+func (s *session) destroy() {
+	s.mux.Lock()
+	defer s.mux.Unlock()
+	if s.cancel != nil {
+		s.cancel <- true
+	}
+	s.endTime = time.Now().UTC()
+	s.renewTill = s.endTime
+	s.sessionKeyExpiration = s.endTime
+}
+
+// valid informs if the TGT is still within the valid time window
+func (s *session) valid() bool {
+	s.mux.RLock()
+	defer s.mux.RUnlock()
+	t := time.Now().UTC()
+	if t.Before(s.endTime) && s.authTime.Before(t) {
+		return true
+	}
+	return false
+}
+
+// tgtDetails is a thread safe way to get the session's realm, TGT and session key values
+func (s *session) tgtDetails() (string, messages.Ticket, types.EncryptionKey) {
+	s.mux.RLock()
+	defer s.mux.RUnlock()
+	return s.realm, s.tgt, s.sessionKey
+}
+
+// timeDetails is a thread safe way to get the session's validity time values
+func (s *session) timeDetails() (string, time.Time, time.Time, time.Time, time.Time) {
+	s.mux.RLock()
+	defer s.mux.RUnlock()
+	return s.realm, s.authTime, s.endTime, s.renewTill, s.sessionKeyExpiration
+}
+
+// enableAutoSessionRenewal turns on the automatic renewal for the client's TGT session.
+func (cl *Client) enableAutoSessionRenewal(s *session) {
+	var timer *time.Timer
+	s.mux.Lock()
+	s.cancel = make(chan bool, 1)
+	s.mux.Unlock()
+	go func(s *session) {
+		for {
+			s.mux.RLock()
+			w := (s.endTime.Sub(time.Now().UTC()) * 5) / 6
+			s.mux.RUnlock()
+			if w < 0 {
+				return
+			}
+			timer = time.NewTimer(w)
+			select {
+			case <-timer.C:
+				renewal, err := cl.refreshSession(s)
+				if err != nil {
+					cl.Log("error refreshing session: %v", err)
+				}
+				if !renewal && err == nil {
+					// end this goroutine as there will have been a new login and new auto renewal goroutine created.
+					return
+				}
+			case <-s.cancel:
+				// cancel has been called. Stop the timer and exit.
+				timer.Stop()
+				return
+			}
+		}
+	}(s)
+}
+
+// renewTGT renews the client's TGT session.
+func (cl *Client) renewTGT(s *session) error {
+	realm, tgt, skey := s.tgtDetails()
+	spn := types.PrincipalName{
+		NameType:   nametype.KRB_NT_SRV_INST,
+		NameString: []string{"krbtgt", realm},
+	}
+	_, tgsRep, err := cl.TGSREQGenerateAndExchange(spn, cl.Credentials.Domain(), tgt, skey, true)
+	if err != nil {
+		return krberror.Errorf(err, krberror.KRBMsgError, "error renewing TGT for %s", realm)
+	}
+	s.update(tgsRep.Ticket, tgsRep.DecryptedEncPart)
+	cl.sessions.update(s)
+	cl.Log("TGT session renewed for %s (EndTime: %v)", realm, tgsRep.DecryptedEncPart.EndTime)
+	return nil
+}
+
+// refreshSession updates either through renewal or creating a new login.
+// The boolean indicates if the update was a renewal.
+func (cl *Client) refreshSession(s *session) (bool, error) {
+	s.mux.RLock()
+	realm := s.realm
+	renewTill := s.renewTill
+	s.mux.RUnlock()
+	cl.Log("refreshing TGT session for %s", realm)
+	if time.Now().UTC().Before(renewTill) {
+		err := cl.renewTGT(s)
+		return true, err
+	}
+	err := cl.realmLogin(realm)
+	return false, err
+}
+
+// ensureValidSession makes sure there is a valid session for the realm
+func (cl *Client) ensureValidSession(realm string) error {
+	s, ok := cl.sessions.get(realm)
+	if ok {
+		s.mux.RLock()
+		d := s.endTime.Sub(s.authTime) / 6
+		if s.endTime.Sub(time.Now().UTC()) > d {
+			s.mux.RUnlock()
+			return nil
+		}
+		s.mux.RUnlock()
+		_, err := cl.refreshSession(s)
+		return err
+	}
+	return cl.realmLogin(realm)
+}
+
+// sessionTGTDetails is a thread safe way to get the TGT and session key values for a realm
+func (cl *Client) sessionTGT(realm string) (tgt messages.Ticket, sessionKey types.EncryptionKey, err error) {
+	err = cl.ensureValidSession(realm)
+	if err != nil {
+		return
+	}
+	s, ok := cl.sessions.get(realm)
+	if !ok {
+		err = fmt.Errorf("could not find TGT session for %s", realm)
+		return
+	}
+	_, tgt, sessionKey = s.tgtDetails()
+	return
+}
+
+func (cl *Client) sessionTimes(realm string) (authTime, endTime, renewTime, sessionExp time.Time, err error) {
+	s, ok := cl.sessions.get(realm)
+	if !ok {
+		err = fmt.Errorf("could not find TGT session for %s", realm)
+		return
+	}
+	_, authTime, endTime, renewTime, sessionExp = s.timeDetails()
+	return
+}
+
+// spnRealm resolves the realm name of a service principal name
+func (cl *Client) spnRealm(spn types.PrincipalName) string {
+	return cl.Config.ResolveRealm(spn.NameString[len(spn.NameString)-1])
+}
diff --git a/vendor/gopkg.in/jcmturner/gokrb5.v7/client/settings.go b/vendor/gopkg.in/jcmturner/gokrb5.v7/client/settings.go
new file mode 100644
index 0000000..12c04c4
--- /dev/null
+++ b/vendor/gopkg.in/jcmturner/gokrb5.v7/client/settings.go
@@ -0,0 +1,69 @@
+package client
+
+import "log"
+
+// Settings holds optional client settings.
+type Settings struct {
+	disablePAFXFast         bool
+	assumePreAuthentication bool
+	preAuthEType            int32
+	logger                  *log.Logger
+}
+
+// NewSettings creates a new client settings struct.
+func NewSettings(settings ...func(*Settings)) *Settings {
+	s := new(Settings)
+	for _, set := range settings {
+		set(s)
+	}
+	return s
+}
+
+// DisablePAFXFAST used to configure the client to not use PA_FX_FAST.
+//
+// s := NewSettings(DisablePAFXFAST(true))
+func DisablePAFXFAST(b bool) func(*Settings) {
+	return func(s *Settings) {
+		s.disablePAFXFast = b
+	}
+}
+
+// DisablePAFXFAST indicates is the client should disable the use of PA_FX_FAST.
+func (s *Settings) DisablePAFXFAST() bool {
+	return s.disablePAFXFast
+}
+
+// AssumePreAuthentication used to configure the client to assume pre-authentication is required.
+//
+// s := NewSettings(AssumePreAuthentication(true))
+func AssumePreAuthentication(b bool) func(*Settings) {
+	return func(s *Settings) {
+		s.assumePreAuthentication = b
+	}
+}
+
+// AssumePreAuthentication indicates if the client should proactively assume using pre-authentication.
+func (s *Settings) AssumePreAuthentication() bool {
+	return s.assumePreAuthentication
+}
+
+// Logger used to configure client with a logger.
+//
+// s := NewSettings(kt, Logger(l))
+func Logger(l *log.Logger) func(*Settings) {
+	return func(s *Settings) {
+		s.logger = l
+	}
+}
+
+// Logger returns the client logger instance.
+func (s *Settings) Logger() *log.Logger {
+	return s.logger
+}
+
+// Log will write to the service's logger if it is configured.
+func (cl *Client) Log(format string, v ...interface{}) {
+	if cl.settings.Logger() != nil {
+		cl.settings.Logger().Printf(format, v...)
+	}
+}