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client.go
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client.go
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package ldapclient
import (
"context"
"crypto/tls"
"fmt"
"net"
"github.com/openshift/library-go/pkg/security/ldaputil"
"golang.org/x/net/proxy"
"k8s.io/client-go/util/cert"
"github.com/go-ldap/ldap/v3"
)
// NewLDAPClientConfig returns a new LDAP client config
func NewLDAPClientConfig(URL, bindDN, bindPassword, CA string, insecure bool) (Config, error) {
url, err := ldaputil.ParseURL(URL)
if err != nil {
return nil, fmt.Errorf("Error parsing URL: %v", err)
}
tlsConfig := &tls.Config{}
if len(CA) > 0 {
roots, err := cert.NewPool(CA)
if err != nil {
return nil, fmt.Errorf("error loading cert pool from ca file %s: %v", CA, err)
}
tlsConfig.RootCAs = roots
}
return &ldapClientConfig{
scheme: url.Scheme,
host: url.Host,
bindDN: bindDN,
bindPassword: bindPassword,
insecure: insecure,
tlsConfig: tlsConfig,
}, nil
}
// ldapClientConfig holds information for connecting to an LDAP server
type ldapClientConfig struct {
// scheme is the LDAP connection scheme, either ldap or ldaps
scheme ldaputil.Scheme
// host is the host:port of the LDAP server
host string
// bindDN is an optional DN to bind with during the search phase.
bindDN string
// bindPassword is an optional password to bind with during the search phase.
bindPassword string
// insecure specifies if TLS is required for the connection. If true, either an ldap://... URL or
// StartTLS must be supported by the server
insecure bool
// tlsConfig holds the TLS options. Only used when insecure=false
tlsConfig *tls.Config
}
// ldapClientConfig is an Config
var _ Config = &ldapClientConfig{}
// ldapDial is the same as ldap.Dial except that it uses a proxyDialer that respects
// the ALL_PROXY environment variable rather than using net.DialTimeout
// While upstream exposes an ldap.DialWithDialer, we can not use it as it takes
// a *net.Dialer as argument rather than an interface, which makes it impossible
// to pass the proxyDialer.
func ldapDial(network, addr string) (*ldap.Conn, error) {
ctx, cancel := context.WithTimeout(context.Background(), ldap.DefaultTimeout)
defer cancel()
c, err := proxy.FromEnvironment().(proxy.ContextDialer).DialContext(ctx, network, addr)
if err != nil {
return nil, ldap.NewError(ldap.ErrorNetwork, err)
}
conn := ldap.NewConn(c, false)
conn.Start()
return conn, nil
}
// ldapDialTLS is the same as ldap.Dial except that it uses a proxyDialer that respects
// the ALL_PROXY environment variable rather than using net.DialTimeout
// While upstream exposes an ldap.DialWithDialer, we can not use it as it takes
// a *net.Dialer as argument rather than an interface, which makes it impossible
// to pass the proxyDialer.
func ldapDialTLS(network, addr string, config *tls.Config) (*ldap.Conn, error) {
ctx, cancel := context.WithTimeout(context.Background(), ldap.DefaultTimeout)
defer cancel()
dc, err := proxy.FromEnvironment().(proxy.ContextDialer).DialContext(ctx, network, addr)
if err != nil {
return nil, ldap.NewError(ldap.ErrorNetwork, err)
}
c := tls.Client(dc, config)
err = c.Handshake()
if err != nil {
// Handshake error, close the established connection before we return an error
dc.Close()
return nil, ldap.NewError(ldap.ErrorNetwork, err)
}
conn := ldap.NewConn(c, true)
conn.Start()
return conn, nil
}
// Connect returns an established LDAP connection, or an error if the connection could not
// be made (or successfully upgraded to TLS). If no error is returned, the caller is responsible for
// closing the connection
func (l *ldapClientConfig) Connect() (ldap.Client, error) {
tlsConfig := l.tlsConfig
// Ensure tlsConfig specifies the server we're connecting to
if tlsConfig != nil && !tlsConfig.InsecureSkipVerify && len(tlsConfig.ServerName) == 0 {
// Add to a copy of the tlsConfig to avoid mutating the original
c := tlsConfig.Clone()
if host, _, err := net.SplitHostPort(l.host); err == nil {
c.ServerName = host
} else {
c.ServerName = l.host
}
tlsConfig = c
}
switch l.scheme {
case ldaputil.SchemeLDAP:
con, err := ldapDial("tcp", l.host)
if err != nil {
return nil, err
}
// If an insecure connection is desired, we're done
if l.insecure {
return con, nil
}
// Attempt to upgrade to TLS
if err := con.StartTLS(tlsConfig); err != nil {
// We're returning an error on a successfully opened connection
// We are responsible for closing the open connection
con.Close()
return nil, err
}
return con, nil
case ldaputil.SchemeLDAPS:
return ldapDialTLS("tcp", l.host, tlsConfig)
default:
return nil, fmt.Errorf("unsupported scheme %q", l.scheme)
}
}
func (l *ldapClientConfig) GetBindCredentials() (string, string) {
return l.bindDN, l.bindPassword
}
func (l *ldapClientConfig) Host() string {
return l.host
}
// String implements Stringer for debugging purposes
func (l *ldapClientConfig) String() string {
return fmt.Sprintf("{Scheme: %v Host: %v BindDN: %v len(BbindPassword): %v Insecure: %v}", l.scheme, l.host, l.bindDN, len(l.bindPassword), l.insecure)
}
// ConnectMaybeBind returns an ldap.Client with an active connection. It attempts
// to bind if bind credentials were provided and would fail if the bind fails.
//
// The caller is responsible for closing the connection.
func ConnectMaybeBind(clientConfig Config) (ldap.Client, error) {
connection, err := clientConfig.Connect()
if err != nil {
return nil, fmt.Errorf("could not connect to the LDAP server: %v", err)
}
if bindDN, bindPassword := clientConfig.GetBindCredentials(); len(bindDN) > 0 {
if err := connection.Bind(bindDN, bindPassword); err != nil {
return nil, fmt.Errorf("could not bind to the LDAP server: %v", err)
}
}
return connection, nil
}