add extra_fe_metadata support to customize federation_entity metada…

docs/config/federation.md

@@ -249,6 +249,25 @@ The `extra_rp_metadata` option is used to add custom key-value pairs to the rely
             another_field: another_value
     ```
 
+## `extra_fe_metadata`
+<span class="badge badge-purple" title="Value Type">mapping / object</span>
+<span class="badge badge-green" title="If this option is required or optional">optional</span>
+
+The `extra_fe_metadata` option is used to add custom key-value pairs to the `federation_entity` metadata section in the entity configuration.
+
+This option is applied **before** any automatic copying of informational claims (controlled by [`publish_informational_claims_in_federation_entity`](#publish_informational_claims_in_federation_entity)). This means that values specified in `extra_fe_metadata` take precedence over automatically copied claims. If a field is set in `extra_fe_metadata`, it will not be overwritten by the automatic copying mechanism.
+
+When `publish_informational_claims_in_federation_entity` is set to `true` (default), OFFA will still automatically copy consistent informational claims from other metadata sections to the federation entity metadata, but only for fields that are not already defined in `extra_fe_metadata`.
+
+??? file "config.yaml"
+
+    ```yaml
+    federation:
+        extra_fe_metadata:
+            custom_federation_field: custom_value
+            another_federation_field: another_value
+    ```
+
 ## `extra_entity_configuration_data`
 <span class="badge badge-purple" title="Value Type">mapping / object</span>
 <span class="badge badge-green" title="If this option is required or optional">optional</span>

internal/config/config.go

@@ -78,6 +78,7 @@ type federationConf struct {
 	OrganizationName             string         `yaml:"organization_name"`
 	OrganizationURI              string         `yaml:"organization_uri"`
 	ExtraRPMetadata              map[string]any `yaml:"extra_rp_metadata"`
+	ExtraFEMetadata              map[string]any `yaml:"extra_fe_metadata"`
 	ExtraEntityConfigurationData map[string]any `yaml:"extra_entity_configuration_data"`
 
 	ConfigurationLifetime                        duration.DurationOption                      `yaml:"configuration_lifetime"`

internal/server/server.go

@@ -2,6 +2,7 @@ package server
 
 import (
 	"fmt"
+	"reflect"
 	"strings"
 	"time"
 
@@ -95,6 +96,9 @@ func initFederationEntity() {
 			OrganizationURI:             fedConfig.OrganizationURI,
 		},
 	}
+	if fedConfig.ExtraFEMetadata != nil && len(fedConfig.ExtraFEMetadata) > 0 {
+		metadata.FederationEntity = applyExtraFEMetadata(fedConfig.ExtraFEMetadata)
+	}
 	if metadata.RelyingParty.Extra == nil {
 		metadata.RelyingParty.Extra = make(map[string]any)
 	}
@@ -195,3 +199,47 @@ func getFullPath(path string) string {
 	}
 	return config.Get().Server.Basepath + path
 }
+
+func applyExtraFEMetadata(extraFE map[string]any) *oidfed.FederationEntityMetadata {
+	fe := &oidfed.FederationEntityMetadata{}
+	v := reflect.ValueOf(fe).Elem()
+	t := v.Type()
+
+	jsonTagToField := make(map[string]string)
+	for i := 0; i < t.NumField(); i++ {
+		field := t.Field(i)
+		jsonTag := field.Tag.Get("json")
+		if jsonTag != "" && jsonTag != "-" {
+			if idx := strings.Index(jsonTag, ","); idx != -1 {
+				jsonTag = jsonTag[:idx]
+			}
+			jsonTagToField[jsonTag] = field.Name
+		}
+	}
+
+	for key, value := range extraFE {
+		if fieldName, ok := jsonTagToField[key]; ok {
+			field := v.FieldByName(fieldName)
+			if field.IsValid() && field.CanSet() {
+				switch field.Kind() {
+				case reflect.String:
+					if strVal, ok := value.(string); ok {
+						field.SetString(strVal)
+					}
+				case reflect.Slice:
+					if sliceVal, ok := value.([]interface{}); ok {
+						strSlice := make([]string, len(sliceVal))
+						for i, v := range sliceVal {
+							if str, ok := v.(string); ok {
+								strSlice[i] = str
+							}
+						}
+						field.Set(reflect.ValueOf(strSlice))
+					}
+				}
+			}
+		}
+	}
+
+	return fe
+}