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client.go
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client.go
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// Copyright (c) HashiCorp, Inc.
// SPDX-License-Identifier: MPL-2.0
package ldaputil
import (
"bytes"
"crypto/tls"
"crypto/x509"
"encoding/binary"
"encoding/hex"
"fmt"
"math"
"net"
"net/url"
"strings"
"sync"
"text/template"
"time"
"github.com/go-ldap/ldap/v3"
hclog "github.com/hashicorp/go-hclog"
multierror "github.com/hashicorp/go-multierror"
"github.com/hashicorp/go-secure-stdlib/tlsutil"
)
type Client struct {
Logger hclog.Logger
LDAP LDAP
}
func (c *Client) DialLDAP(cfg *ConfigEntry) (Connection, error) {
var retErr *multierror.Error
var conn Connection
urls := strings.Split(cfg.Url, ",")
for _, uut := range urls {
u, err := url.Parse(uut)
if err != nil {
retErr = multierror.Append(retErr, fmt.Errorf(fmt.Sprintf("error parsing url %q: {{err}}", uut), err))
continue
}
host, port, err := net.SplitHostPort(u.Host)
if err != nil {
host = u.Host
}
var tlsConfig *tls.Config
dialer := net.Dialer{
Timeout: time.Duration(cfg.ConnectionTimeout) * time.Second,
}
switch u.Scheme {
case "ldap":
if port == "" {
port = "389"
}
fullAddr := fmt.Sprintf("%s://%s", u.Scheme, net.JoinHostPort(host, port))
opt := ldap.DialWithDialer(&dialer)
conn, err = c.LDAP.DialURL(fullAddr, opt)
if err != nil {
break
}
if conn == nil {
err = fmt.Errorf("empty connection after dialing")
break
}
if cfg.StartTLS {
tlsConfig, err = getTLSConfig(cfg, host)
if err != nil {
break
}
err = conn.StartTLS(tlsConfig)
}
case "ldaps":
if port == "" {
port = "636"
}
tlsConfig, err = getTLSConfig(cfg, host)
if err != nil {
break
}
fullAddr := fmt.Sprintf("%s://%s", u.Scheme, net.JoinHostPort(host, port))
opt := ldap.DialWithDialer(&dialer)
tls := ldap.DialWithTLSConfig(tlsConfig)
conn, err = c.LDAP.DialURL(fullAddr, opt, tls)
if err != nil {
break
}
default:
retErr = multierror.Append(retErr, fmt.Errorf("invalid LDAP scheme in url %q", net.JoinHostPort(host, port)))
continue
}
if err == nil {
if retErr != nil {
if c.Logger.IsDebug() {
c.Logger.Debug("errors connecting to some hosts", "error", retErr.Error())
}
}
retErr = nil
break
}
retErr = multierror.Append(retErr, fmt.Errorf(fmt.Sprintf("error connecting to host %q: {{err}}", uut), err))
}
if retErr != nil {
return nil, retErr
}
if timeout := cfg.RequestTimeout; timeout > 0 {
conn.SetTimeout(time.Duration(timeout) * time.Second)
}
return conn, nil
}
/*
* Searches for a username in the ldap server, returning a minimal subset of the
* user's attributes (if found)
*/
func (c *Client) makeLdapSearchRequest(cfg *ConfigEntry, conn Connection, username string) (*ldap.SearchResult, error) {
// Note: The logic below drives the logic in ConfigEntry.Validate().
// If updated, please update there as well.
var err error
if cfg.BindPassword != "" {
err = conn.Bind(cfg.BindDN, cfg.BindPassword)
} else {
err = conn.UnauthenticatedBind(cfg.BindDN)
}
if err != nil {
return nil, fmt.Errorf("LDAP bind (service) failed: %w", err)
}
renderedFilter, err := c.RenderUserSearchFilter(cfg, username)
if err != nil {
return nil, err
}
if c.Logger.IsDebug() {
c.Logger.Debug("discovering user", "userdn", cfg.UserDN, "filter", renderedFilter)
}
ldapRequest := &ldap.SearchRequest{
BaseDN: cfg.UserDN,
DerefAliases: ldapDerefAliasMap[cfg.DerefAliases],
Scope: ldap.ScopeWholeSubtree,
Filter: renderedFilter,
SizeLimit: 2, // Should be only 1 result. Any number larger (2 or more) means access denied.
Attributes: []string{
cfg.UserAttr, // Return only needed attributes
},
}
result, err := conn.Search(ldapRequest)
if err != nil {
return nil, err
}
return result, nil
}
/*
* Discover and return the bind string for the user attempting to authenticate, as well as the
* value to use for the identity alias.
* This is handled in one of several ways:
*
* 1. If DiscoverDN is set, the user object will be searched for using userdn (base search path)
* and userattr (the attribute that maps to the provided username) or user search filter.
* The bind will either be anonymous or use binddn and bindpassword if they were provided.
* 2. If upndomain is set, the user dn and alias attribte are constructed as 'username@upndomain'.
* See https://msdn.microsoft.com/en-us/library/cc223499.aspx
*
*/
func (c *Client) GetUserBindDN(cfg *ConfigEntry, conn Connection, username string) (string, error) {
bindDN := ""
// Note: The logic below drives the logic in ConfigEntry.Validate().
// If updated, please update there as well.
if cfg.DiscoverDN || (cfg.BindDN != "" && cfg.BindPassword != "") {
result, err := c.makeLdapSearchRequest(cfg, conn, username)
if err != nil {
return bindDN, fmt.Errorf("LDAP search for binddn failed %w", err)
}
if len(result.Entries) != 1 {
return bindDN, fmt.Errorf("LDAP search for binddn 0 or not unique")
}
bindDN = result.Entries[0].DN
} else {
if cfg.UPNDomain != "" {
bindDN = fmt.Sprintf("%s@%s", EscapeLDAPValue(username), cfg.UPNDomain)
} else {
bindDN = fmt.Sprintf("%s=%s,%s", cfg.UserAttr, EscapeLDAPValue(username), cfg.UserDN)
}
}
return bindDN, nil
}
func (c *Client) RenderUserSearchFilter(cfg *ConfigEntry, username string) (string, error) {
// The UserFilter can be blank if not set, or running this version of the code
// on an existing ldap configuration
if cfg.UserFilter == "" {
cfg.UserFilter = "({{.UserAttr}}={{.Username}})"
}
// If userfilter was defined, resolve it as a Go template and use the query to
// find the login user
if c.Logger.IsDebug() {
c.Logger.Debug("compiling search filter", "search_filter", cfg.UserFilter)
}
// Parse the configuration as a template.
// Example template "({{.UserAttr}}={{.Username}})"
t, err := template.New("queryTemplate").Parse(cfg.UserFilter)
if err != nil {
return "", fmt.Errorf("LDAP search failed due to template compilation error: %w", err)
}
// Build context to pass to template - we will be exposing UserDn and Username.
context := struct {
UserAttr string
Username string
}{
ldap.EscapeFilter(cfg.UserAttr),
ldap.EscapeFilter(username),
}
if cfg.UPNDomain != "" {
context.UserAttr = "userPrincipalName"
// Intentionally, calling EscapeFilter(...) (vs EscapeValue) since the
// username is being injected into a search filter.
// As an untrusted string, the username must be escaped according to RFC
// 4515, in order to prevent attackers from injecting characters that could modify the filter
context.Username = fmt.Sprintf("%s@%s", ldap.EscapeFilter(username), cfg.UPNDomain)
}
// Execute the template. Note that the template context contains escaped input and does
// not provide behavior via functions. Additionally, no function map has been provided
// during template initialization. The only template functions available during execution
// are the predefined global functions: https://pkg.go.dev/text/template#hdr-Functions
var renderedFilter bytes.Buffer
if err := t.Execute(&renderedFilter, context); err != nil {
return "", fmt.Errorf("LDAP search failed due to template parsing error: %w", err)
}
return renderedFilter.String(), nil
}
/*
* Returns the value to be used for the entity alias of this user
* This is handled in one of several ways:
*
* 1. If DiscoverDN is set, the user will be searched for using userdn (base search path)
* and userattr (the attribute that maps to the provided username) or user search filter.
* The bind will either be anonymous or use binddn and bindpassword if they were provided.
* 2. If upndomain is set, the alias attribte is constructed as 'username@upndomain'.
*
*/
func (c *Client) GetUserAliasAttributeValue(cfg *ConfigEntry, conn Connection, username string) (string, error) {
aliasAttributeValue := ""
// Note: The logic below drives the logic in ConfigEntry.Validate().
// If updated, please update there as well.
if cfg.DiscoverDN || (cfg.BindDN != "" && cfg.BindPassword != "") {
result, err := c.makeLdapSearchRequest(cfg, conn, username)
if err != nil {
return aliasAttributeValue, fmt.Errorf("LDAP search for entity alias attribute failed: %w", err)
}
if len(result.Entries) != 1 {
return aliasAttributeValue, fmt.Errorf("LDAP search for entity alias attribute 0 or not unique")
}
if len(result.Entries[0].Attributes) != 1 {
return aliasAttributeValue, fmt.Errorf("LDAP attribute missing for entity alias mapping")
}
if len(result.Entries[0].Attributes[0].Values) != 1 {
return aliasAttributeValue, fmt.Errorf("LDAP entity alias attribute %s empty or not unique for entity alias mapping", cfg.UserAttr)
}
aliasAttributeValue = result.Entries[0].Attributes[0].Values[0]
} else {
if cfg.UPNDomain != "" {
aliasAttributeValue = fmt.Sprintf("%s@%s", EscapeLDAPValue(username), cfg.UPNDomain)
} else {
aliasAttributeValue = fmt.Sprintf("%s=%s,%s", cfg.UserAttr, EscapeLDAPValue(username), cfg.UserDN)
}
}
return aliasAttributeValue, nil
}
/*
* Returns the DN of the object representing the authenticated user.
*/
func (c *Client) GetUserDN(cfg *ConfigEntry, conn Connection, bindDN, username string) (string, error) {
userDN := ""
if cfg.UPNDomain != "" {
// Find the distinguished name for the user if userPrincipalName used for login
filter := fmt.Sprintf("(userPrincipalName=%s@%s)", EscapeLDAPValue(username), cfg.UPNDomain)
if c.Logger.IsDebug() {
c.Logger.Debug("searching upn", "userdn", cfg.UserDN, "filter", filter)
}
result, err := conn.Search(&ldap.SearchRequest{
BaseDN: cfg.UserDN,
Scope: ldap.ScopeWholeSubtree,
DerefAliases: ldapDerefAliasMap[cfg.DerefAliases],
Filter: filter,
SizeLimit: math.MaxInt32,
})
if err != nil {
return userDN, fmt.Errorf("LDAP search failed for detecting user: %w", err)
}
for _, e := range result.Entries {
userDN = e.DN
}
} else {
userDN = bindDN
}
return userDN, nil
}
func (c *Client) performLdapFilterGroupsSearch(cfg *ConfigEntry, conn Connection, userDN string, username string) ([]*ldap.Entry, error) {
if cfg.GroupFilter == "" {
c.Logger.Warn("groupfilter is empty, will not query server")
return make([]*ldap.Entry, 0), nil
}
if cfg.GroupDN == "" {
c.Logger.Warn("groupdn is empty, will not query server")
return make([]*ldap.Entry, 0), nil
}
// If groupfilter was defined, resolve it as a Go template and use the query for
// returning the user's groups
if c.Logger.IsDebug() {
c.Logger.Debug("compiling group filter", "group_filter", cfg.GroupFilter)
}
// Parse the configuration as a template.
// Example template "(&(objectClass=group)(member:1.2.840.113556.1.4.1941:={{.UserDN}}))"
t, err := template.New("queryTemplate").Parse(cfg.GroupFilter)
if err != nil {
return nil, fmt.Errorf("LDAP search failed due to template compilation error: %w", err)
}
// Build context to pass to template - we will be exposing UserDn and Username.
context := struct {
UserDN string
Username string
}{
ldap.EscapeFilter(userDN),
ldap.EscapeFilter(username),
}
var renderedQuery bytes.Buffer
if err := t.Execute(&renderedQuery, context); err != nil {
return nil, fmt.Errorf("LDAP search failed due to template parsing error: %w", err)
}
if c.Logger.IsDebug() {
c.Logger.Debug("searching", "groupdn", cfg.GroupDN, "rendered_query", renderedQuery.String())
}
result, err := conn.Search(&ldap.SearchRequest{
BaseDN: cfg.GroupDN,
Scope: ldap.ScopeWholeSubtree,
DerefAliases: ldapDerefAliasMap[cfg.DerefAliases],
Filter: renderedQuery.String(),
Attributes: []string{
cfg.GroupAttr,
},
SizeLimit: math.MaxInt32,
})
if err != nil {
return nil, fmt.Errorf("LDAP search failed: %w", err)
}
return result.Entries, nil
}
func (c *Client) performLdapFilterGroupsSearchPaging(cfg *ConfigEntry, conn PagingConnection, userDN string, username string) ([]*ldap.Entry, error) {
if cfg.GroupFilter == "" {
c.Logger.Warn("groupfilter is empty, will not query server")
return make([]*ldap.Entry, 0), nil
}
if cfg.GroupDN == "" {
c.Logger.Warn("groupdn is empty, will not query server")
return make([]*ldap.Entry, 0), nil
}
// If groupfilter was defined, resolve it as a Go template and use the query for
// returning the user's groups
if c.Logger.IsDebug() {
c.Logger.Debug("compiling group filter", "group_filter", cfg.GroupFilter)
}
// Parse the configuration as a template.
// Example template "(&(objectClass=group)(member:1.2.840.113556.1.4.1941:={{.UserDN}}))"
t, err := template.New("queryTemplate").Parse(cfg.GroupFilter)
if err != nil {
return nil, fmt.Errorf("LDAP search failed due to template compilation error: %w", err)
}
// Build context to pass to template - we will be exposing UserDn and Username.
context := struct {
UserDN string
Username string
}{
ldap.EscapeFilter(userDN),
ldap.EscapeFilter(username),
}
// Execute the template. Note that the template context contains escaped input and does
// not provide behavior via functions. Additionally, no function map has been provided
// during template initialization. The only template functions available during execution
// are the predefined global functions: https://pkg.go.dev/text/template#hdr-Functions
var renderedQuery bytes.Buffer
if err := t.Execute(&renderedQuery, context); err != nil {
return nil, fmt.Errorf("LDAP search failed due to template parsing error: %w", err)
}
if c.Logger.IsDebug() {
c.Logger.Debug("searching", "groupdn", cfg.GroupDN, "rendered_query", renderedQuery.String())
}
result, err := conn.SearchWithPaging(&ldap.SearchRequest{
BaseDN: cfg.GroupDN,
Scope: ldap.ScopeWholeSubtree,
DerefAliases: ldapDerefAliasMap[cfg.DerefAliases],
Filter: renderedQuery.String(),
Attributes: []string{
cfg.GroupAttr,
},
SizeLimit: math.MaxInt32,
}, uint32(cfg.MaximumPageSize))
if err != nil {
return nil, fmt.Errorf("LDAP search failed: %w", err)
}
return result.Entries, nil
}
func sidBytesToString(b []byte) (string, error) {
reader := bytes.NewReader(b)
var revision, subAuthorityCount uint8
var identifierAuthorityParts [3]uint16
if err := binary.Read(reader, binary.LittleEndian, &revision); err != nil {
return "", fmt.Errorf(fmt.Sprintf("SID %#v convert failed reading Revision: {{err}}", b), err)
}
if err := binary.Read(reader, binary.LittleEndian, &subAuthorityCount); err != nil {
return "", fmt.Errorf(fmt.Sprintf("SID %#v convert failed reading SubAuthorityCount: {{err}}", b), err)
}
if err := binary.Read(reader, binary.BigEndian, &identifierAuthorityParts); err != nil {
return "", fmt.Errorf(fmt.Sprintf("SID %#v convert failed reading IdentifierAuthority: {{err}}", b), err)
}
identifierAuthority := (uint64(identifierAuthorityParts[0]) << 32) + (uint64(identifierAuthorityParts[1]) << 16) + uint64(identifierAuthorityParts[2])
subAuthority := make([]uint32, subAuthorityCount)
if err := binary.Read(reader, binary.LittleEndian, &subAuthority); err != nil {
return "", fmt.Errorf(fmt.Sprintf("SID %#v convert failed reading SubAuthority: {{err}}", b), err)
}
result := fmt.Sprintf("S-%d-%d", revision, identifierAuthority)
for _, subAuthorityPart := range subAuthority {
result += fmt.Sprintf("-%d", subAuthorityPart)
}
return result, nil
}
func (c *Client) performLdapTokenGroupsSearch(cfg *ConfigEntry, conn Connection, userDN string) ([]*ldap.Entry, error) {
var wg sync.WaitGroup
var lock sync.Mutex
taskChan := make(chan string)
maxWorkers := 10
result, err := conn.Search(&ldap.SearchRequest{
BaseDN: userDN,
Scope: ldap.ScopeBaseObject,
DerefAliases: ldapDerefAliasMap[cfg.DerefAliases],
Filter: "(objectClass=*)",
Attributes: []string{
"tokenGroups",
},
SizeLimit: 1,
})
if err != nil {
return nil, fmt.Errorf("LDAP search failed: %w", err)
}
if len(result.Entries) == 0 {
c.Logger.Warn("unable to read object for group attributes", "userdn", userDN, "groupattr", cfg.GroupAttr)
return make([]*ldap.Entry, 0), nil
}
userEntry := result.Entries[0]
groupAttrValues := userEntry.GetRawAttributeValues("tokenGroups")
groupEntries := make([]*ldap.Entry, 0, len(groupAttrValues))
for i := 0; i < maxWorkers; i++ {
wg.Add(1)
go func() {
defer wg.Done()
for sid := range taskChan {
groupResult, err := conn.Search(&ldap.SearchRequest{
BaseDN: fmt.Sprintf("<SID=%s>", sid),
Scope: ldap.ScopeBaseObject,
DerefAliases: ldapDerefAliasMap[cfg.DerefAliases],
Filter: "(objectClass=*)",
Attributes: []string{
"1.1", // RFC no attributes
},
SizeLimit: 1,
})
if err != nil {
c.Logger.Warn("unable to read the group sid", "sid", sid)
continue
}
if len(groupResult.Entries) == 0 {
c.Logger.Warn("unable to find the group", "sid", sid)
continue
}
lock.Lock()
groupEntries = append(groupEntries, groupResult.Entries[0])
lock.Unlock()
}
}()
}
for _, sidBytes := range groupAttrValues {
sidString, err := sidBytesToString(sidBytes)
if err != nil {
c.Logger.Warn("unable to read sid", "err", err)
continue
}
taskChan <- sidString
}
close(taskChan)
wg.Wait()
return groupEntries, nil
}
/*
* getLdapGroups queries LDAP and returns a slice describing the set of groups the authenticated user is a member of.
*
* If cfg.UseTokenGroups is true then the search is performed directly on the userDN.
* The values of those attributes are converted to string SIDs, and then looked up to get ldap.Entry objects.
* Otherwise, the search query is constructed according to cfg.GroupFilter, and run in context of cfg.GroupDN.
* Groups will be resolved from the query results by following the attribute defined in cfg.GroupAttr.
*
* cfg.GroupFilter is a go template and is compiled with the following context: [UserDN, Username]
* UserDN - The DN of the authenticated user
* Username - The Username of the authenticated user
*
* Example:
* cfg.GroupFilter = "(&(objectClass=group)(member:1.2.840.113556.1.4.1941:={{.UserDN}}))"
* cfg.GroupDN = "OU=Groups,DC=myorg,DC=com"
* cfg.GroupAttr = "cn"
*
* NOTE - If cfg.GroupFilter is empty, no query is performed and an empty result slice is returned.
*
*/
func (c *Client) GetLdapGroups(cfg *ConfigEntry, conn Connection, userDN string, username string) ([]string, error) {
var entries []*ldap.Entry
var err error
if cfg.UseTokenGroups {
entries, err = c.performLdapTokenGroupsSearch(cfg, conn, userDN)
} else {
if paging, ok := conn.(PagingConnection); ok && cfg.MaximumPageSize > 0 {
entries, err = c.performLdapFilterGroupsSearchPaging(cfg, paging, userDN, username)
} else {
entries, err = c.performLdapFilterGroupsSearch(cfg, conn, userDN, username)
}
}
if err != nil {
return nil, err
}
// retrieve the groups in a string/bool map as a structure to avoid duplicates inside
ldapMap := make(map[string]bool)
for _, e := range entries {
dn, err := ldap.ParseDN(e.DN)
if err != nil || len(dn.RDNs) == 0 {
continue
}
// Enumerate attributes of each result, parse out CN and add as group
values := e.GetAttributeValues(cfg.GroupAttr)
if len(values) > 0 {
for _, val := range values {
groupCN := getCN(cfg, val)
ldapMap[groupCN] = true
}
} else {
// If groupattr didn't resolve, use self (enumerating group objects)
groupCN := getCN(cfg, e.DN)
ldapMap[groupCN] = true
}
}
ldapGroups := make([]string, 0, len(ldapMap))
for key := range ldapMap {
ldapGroups = append(ldapGroups, key)
}
return ldapGroups, nil
}
// EscapeLDAPValue is exported because a plugin uses it outside this package.
// EscapeLDAPValue will properly escape the input string as an ldap value
// rfc4514 states the following must be escaped:
// - leading space or hash
// - trailing space
// - special characters '"', '+', ',', ';', '<', '>', '\\'
// - hex
func EscapeLDAPValue(input string) string {
if input == "" {
return ""
}
buf := bytes.Buffer{}
escFn := func(c byte) {
buf.WriteByte('\\')
buf.WriteByte(c)
}
inputLen := len(input)
for i := 0; i < inputLen; i++ {
char := input[i]
switch {
case i == 0 && char == ' ' || char == '#':
// leading space or hash.
escFn(char)
continue
case i == inputLen-1 && char == ' ':
// trailing space.
escFn(char)
continue
case specialChar(char):
escFn(char)
continue
case char < ' ' || char > '~':
// anything that's not between the ascii space and tilde must be hex
buf.WriteByte('\\')
buf.WriteString(hex.EncodeToString([]byte{char}))
continue
default:
// everything remaining, doesn't need to be escaped
buf.WriteByte(char)
}
}
return buf.String()
}
func specialChar(char byte) bool {
switch char {
case '"', '+', ',', ';', '<', '>', '\\':
return true
default:
return false
}
}
/*
* Parses a distinguished name and returns the CN portion.
* Given a non-conforming string (such as an already-extracted CN),
* it will be returned as-is.
*/
func getCN(cfg *ConfigEntry, dn string) string {
parsedDN, err := ldap.ParseDN(dn)
if err != nil || len(parsedDN.RDNs) == 0 {
// It was already a CN, return as-is
return dn
}
for _, rdn := range parsedDN.RDNs {
for _, rdnAttr := range rdn.Attributes {
if cfg.UsePre111GroupCNBehavior == nil || *cfg.UsePre111GroupCNBehavior {
if rdnAttr.Type == "CN" {
return rdnAttr.Value
}
} else {
if strings.EqualFold(rdnAttr.Type, "CN") {
return rdnAttr.Value
}
}
}
}
// Default, return self
return dn
}
func getTLSConfig(cfg *ConfigEntry, host string) (*tls.Config, error) {
tlsConfig := &tls.Config{
ServerName: host,
}
if cfg.TLSMinVersion != "" {
tlsMinVersion, ok := tlsutil.TLSLookup[cfg.TLSMinVersion]
if !ok {
return nil, fmt.Errorf("invalid 'tls_min_version' in config")
}
tlsConfig.MinVersion = tlsMinVersion
}
if cfg.TLSMaxVersion != "" {
tlsMaxVersion, ok := tlsutil.TLSLookup[cfg.TLSMaxVersion]
if !ok {
return nil, fmt.Errorf("invalid 'tls_max_version' in config")
}
tlsConfig.MaxVersion = tlsMaxVersion
}
if cfg.InsecureTLS {
tlsConfig.InsecureSkipVerify = true
}
if cfg.Certificate != "" {
caPool := x509.NewCertPool()
ok := caPool.AppendCertsFromPEM([]byte(cfg.Certificate))
if !ok {
return nil, fmt.Errorf("could not append CA certificate")
}
tlsConfig.RootCAs = caPool
}
if cfg.ClientTLSCert != "" && cfg.ClientTLSKey != "" {
certificate, err := tls.X509KeyPair([]byte(cfg.ClientTLSCert), []byte(cfg.ClientTLSKey))
if err != nil {
return nil, fmt.Errorf("failed to parse client X509 key pair: %w", err)
}
tlsConfig.Certificates = append(tlsConfig.Certificates, certificate)
} else if cfg.ClientTLSCert != "" || cfg.ClientTLSKey != "" {
return nil, fmt.Errorf("both client_tls_cert and client_tls_key must be set")
}
return tlsConfig, nil
}