refactor: remove forward auth, move module net/http to net/gphttp

internal/net/gphttp/middleware/x_forwarded.go

@@ -0,0 +1,45 @@
+package middleware
+
+import (
+	"net"
+	"net/http"
+	"strings"
+
+	"github.com/yusing/go-proxy/internal/net/gphttp/httpheaders"
+)
+
+type (
+	setXForwarded  struct{}
+	hideXForwarded struct{}
+)
+
+var (
+	SetXForwarded  = NewMiddleware[setXForwarded]()
+	HideXForwarded = NewMiddleware[hideXForwarded]()
+)
+
+// before implements RequestModifier.
+func (setXForwarded) before(w http.ResponseWriter, r *http.Request) (proceed bool) {
+	r.Header.Del(httpheaders.HeaderXForwardedFor)
+	clientIP, _, err := net.SplitHostPort(r.RemoteAddr)
+	if err == nil {
+		r.Header.Set(httpheaders.HeaderXForwardedFor, clientIP)
+	}
+	return true
+}
+
+// before implements RequestModifier.
+func (hideXForwarded) before(w http.ResponseWriter, r *http.Request) (proceed bool) {
+	toDelete := make([]string, 0, len(r.Header))
+	for k := range r.Header {
+		if strings.HasPrefix(k, "X-Forwarded-") {
+			toDelete = append(toDelete, k)
+		}
+	}
+
+	for _, k := range toDelete {
+		r.Header.Del(k)
+	}
+
+	return true
+}