fix: 快照自定义客户端 IP 请求头

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

backend/internal/server/middleware/session_binding.go

@@ -17,12 +17,12 @@ import (
 // 接管解析，关闭时使用 Gin 的 server.trusted_proxies 可信代理链。
 func SessionBindingContext(cfg *config.Config) gin.HandlerFunc {
 	return func(c *gin.Context) {
-		trustForwarded := cfg.TrustForwardedIPForAPIKeyACL()
-		ip.SetLegacyForwardedIPTrust(c, trustForwarded)
+		forwardedIPSettings := cfg.ForwardedClientIPSettings()
+		ip.SetForwardedIPSettings(c, forwardedIPSettings.TrustForwardedIP, forwardedIPSettings.Headers)
 		userAgent := normalizePersistentText(c.Request.UserAgent(), maxPersistentUserAgentBytes)
 		c.Request.Header.Set("User-Agent", userAgent)
 		binding := &service.SessionBinding{
-			IP:        ip.GetSecurityClientIP(c, trustForwarded),
+			IP:        ip.GetSecurityClientIP(c, forwardedIPSettings.TrustForwardedIP),
 			UserAgent: userAgent,
 		}
 		c.Request = c.Request.WithContext(service.WithSessionBinding(c.Request.Context(), binding))

backend/internal/server/middleware/session_binding_test.go

@@ -8,6 +8,7 @@ import (
 	"testing"
 
 	"github.com/Wei-Shaw/sub2api/internal/config"
+	"github.com/Wei-Shaw/sub2api/internal/pkg/ip"
 	"github.com/Wei-Shaw/sub2api/internal/service"
 
 	"github.com/gin-gonic/gin"
@@ -55,6 +56,39 @@ func TestSessionBindingContextFollowsForwardedIPSwitch(t *testing.T) {
 	}
 }
 
+func TestSessionBindingContextSnapshotsForwardedModeAndHeaders(t *testing.T) {
+	gin.SetMode(gin.TestMode)
+
+	cfg := &config.Config{}
+	cfg.SetForwardedClientIPSettings(true, []string{"X-Initial-IP"})
+
+	r := gin.New()
+	require.NoError(t, r.SetTrustedProxies(nil))
+	r.Use(SessionBindingContext(cfg))
+	r.GET("/t", func(c *gin.Context) {
+		binding := service.SessionBindingFromContext(c.Request.Context())
+		require.NotNil(t, binding)
+		require.Equal(t, "1.2.3.4", binding.IP)
+
+		cfg.SetForwardedClientIPSettings(false, []string{"X-Changed-IP"})
+		require.Equal(t, "1.2.3.4", ip.GetSecurityClientIP(c, false))
+		c.Status(200)
+	})
+
+	w := httptest.NewRecorder()
+	req := httptest.NewRequest("GET", "/t", nil)
+	req.RemoteAddr = "9.9.9.9:12345"
+	req.Header.Set("X-Initial-IP", "1.2.3.4")
+	req.Header.Set("X-Changed-IP", "4.4.4.4")
+	req.Header.Set("X-Real-IP", "8.8.8.8")
+	r.ServeHTTP(w, req)
+
+	require.Equal(t, 200, w.Code)
+	runtimeSettings := cfg.ForwardedClientIPSettings()
+	require.False(t, runtimeSettings.TrustForwardedIP)
+	require.Equal(t, []string{"X-Changed-IP"}, runtimeSettings.Headers)
+}
+
 func TestSessionBindingContextBoundsPersistedUserAgent(t *testing.T) {
 	cfg := &config.Config{}
 	r := gin.New()