Add empty anonymous group search configs

ldap/client.go

@@ -215,7 +215,8 @@ type Attribute struct {
 // the WithGroups option is specified, it will also return the user's groups
 // from the directory.
 //
-// Supported options: WithUserAttributes, WithGroups, WithDialer, WithURLs, WithLowerUserAttributeKeys
+// Supported options: WithUserAttributes, WithGroups, WithDialer, WithURLs,
+// WithLowerUserAttributeKeys, WithEmptyAnonymousGroupSearch
 func (c *Client) Authenticate(ctx context.Context, username, password string, opt ...Option) (*AuthResult, error) {
 	const op = "ldap.(Client).Authenticate"
 	if username == "" {
@@ -289,7 +290,14 @@ func (c *Client) Authenticate(ctx context.Context, username, password string, op
 	}
 
 	if c.conf.AnonymousGroupSearch {
-		if err := c.conn.UnauthenticatedBind(userDN); err != nil {
+		// Some LDAP servers will reject anonymous group searches if userDN is
+		// included in the query.
+		dn := userDN
+		if c.conf.AllowEmptyAnonymousGroupSearch || opts.withEmptyAnonymousGroupSearch {
+			dn = ""
+		}
+
+		if err := c.conn.UnauthenticatedBind(dn); err != nil {
 			return nil, fmt.Errorf("%s: group search anonymous bind failed: %w", op, err)
 		}
 	}

ldap/client_exported_test.go

@@ -337,6 +337,72 @@ func TestClient_Authenticate(t *testing.T) {
 			opts:       []ldap.Option{ldap.WithGroups()},
 			wantGroups: []string{groups[0].DN},
 		},
+		{
+			name:     "success-with-anon-bind-groups-empty-userdn",
+			username: "alice",
+			password: "password",
+			clientConfig: &ldap.ClientConfig{
+				URLs:                           []string{fmt.Sprintf("ldaps://127.0.0.1:%d", td.Port())},
+				Certificates:                   []string{td.Cert()},
+				DiscoverDN:                     true,
+				UserDN:                         testdirectory.DefaultUserDN,
+				GroupDN:                        testdirectory.DefaultGroupDN,
+				UseTokenGroups:                 true,
+				AnonymousGroupSearch:           true,
+				AllowEmptyAnonymousGroupSearch: true,
+			},
+			opts:       []ldap.Option{ldap.WithGroups()},
+			wantGroups: []string{groups[0].DN},
+		},
+		{
+			name:     "success-with-anon-bind-groups-empty-userdn-opt",
+			username: "alice",
+			password: "password",
+			clientConfig: &ldap.ClientConfig{
+				URLs:                 []string{fmt.Sprintf("ldaps://127.0.0.1:%d", td.Port())},
+				Certificates:         []string{td.Cert()},
+				DiscoverDN:           true,
+				UserDN:               testdirectory.DefaultUserDN,
+				GroupDN:              testdirectory.DefaultGroupDN,
+				UseTokenGroups:       true,
+				AnonymousGroupSearch: true,
+			},
+			opts:       []ldap.Option{ldap.WithGroups(), ldap.WithEmptyAnonymousGroupSearch()},
+			wantGroups: []string{groups[0].DN},
+		},
+		{
+			name:     "success-with-anon-bind-upn-domain-empty-userdn",
+			username: "eve",
+			password: "password",
+			clientConfig: &ldap.ClientConfig{
+				URLs:                           []string{fmt.Sprintf("ldaps://127.0.0.1:%d", td.Port())},
+				Certificates:                   []string{td.Cert()},
+				DiscoverDN:                     true,
+				UserDN:                         testdirectory.DefaultUserDN,
+				GroupDN:                        testdirectory.DefaultGroupDN,
+				UPNDomain:                      "example.com",
+				AnonymousGroupSearch:           true,
+				AllowEmptyAnonymousGroupSearch: true,
+			},
+			opts:       []ldap.Option{ldap.WithGroups()},
+			wantGroups: []string{groups[0].DN},
+		},
+		{
+			name:     "success-with-anon-bind-upn-domain-empty-userdn-opt",
+			username: "eve",
+			password: "password",
+			clientConfig: &ldap.ClientConfig{
+				URLs:                 []string{fmt.Sprintf("ldaps://127.0.0.1:%d", td.Port())},
+				Certificates:         []string{td.Cert()},
+				DiscoverDN:           true,
+				UserDN:               testdirectory.DefaultUserDN,
+				GroupDN:              testdirectory.DefaultGroupDN,
+				UPNDomain:            "example.com",
+				AnonymousGroupSearch: true,
+			},
+			opts:       []ldap.Option{ldap.WithGroups(), ldap.WithEmptyAnonymousGroupSearch()},
+			wantGroups: []string{groups[0].DN},
+		},
 		{
 			name:     "success-with-binddn",
 			username: "alice",

ldap/config.go

@@ -87,6 +87,10 @@ type ClientConfig struct {
 	// for the initial connection test).
 	AnonymousGroupSearch bool `json:"anonymous_group_search"`
 
+	// AllowEmptyAnonymousGroupSearches: if true it removes the userDN from
+	// unauthenticated group searches (optional).
+	AllowEmptyAnonymousGroupSearch bool `json:"allow_empty_anonymous_group_search"`
+
 	// GroupDN is the distinguished name to use as base when searching for group
 	// membership (eg: ou=Groups,dc=example,dc=org)
 	GroupDN string `json:"groupdn"`

ldap/options.go

@@ -8,16 +8,17 @@ package ldap
 type Option func(interface{})
 
 type configOptions struct {
-	withURLs                   []string
-	withInsecureTLS            bool
-	withTLSMinVersion          string
-	withTLSMaxVersion          string
-	withCertificates           []string
-	withClientTLSCert          string
-	withClientTLSKey           string
-	withGroups                 bool
-	withUserAttributes         bool
-	withLowerUserAttributeKeys bool
+	withURLs                      []string
+	withInsecureTLS               bool
+	withTLSMinVersion             string
+	withTLSMaxVersion             string
+	withCertificates              []string
+	withClientTLSCert             string
+	withClientTLSKey              string
+	withGroups                    bool
+	withUserAttributes            bool
+	withLowerUserAttributeKeys    bool
+	withEmptyAnonymousGroupSearch bool
 }
 
 func configDefaults() configOptions {
@@ -88,6 +89,16 @@ func WithLowerUserAttributeKeys() Option {
 	}
 }
 
+// WithEmptyAnonymousGroupSearch removes userDN from anonymous group searches.
+func WithEmptyAnonymousGroupSearch() Option {
+	return func(o interface{}) {
+		switch v := o.(type) {
+		case *configOptions:
+			v.withEmptyAnonymousGroupSearch = true
+		}
+	}
+}
+
 func withTLSMinVersion(version string) Option {
 	return func(o interface{}) {
 		switch v := o.(type) {