security fix

security_http.go

@@ -0,0 +1,62 @@
+package main
+
+import (
+	"fmt"
+	"net/http"
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+const maxAdminRequestBody = 8 << 20
+
+// securePanelHandler applies baseline browser protections and a global request
+// body ceiling. Endpoint-specific handlers may impose a smaller limit.
+func securePanelHandler(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("X-Content-Type-Options", "nosniff")
+		w.Header().Set("X-Frame-Options", "DENY")
+		w.Header().Set("Referrer-Policy", "no-referrer")
+		w.Header().Set("Permissions-Policy", "camera=(), microphone=(), geolocation=(), payment=()")
+		w.Header().Set("Cross-Origin-Opener-Policy", "same-origin")
+		w.Header().Set("Content-Security-Policy", "default-src 'self'; base-uri 'none'; frame-ancestors 'none'; object-src 'none'; form-action 'self'; img-src 'self' data:; connect-src 'self'; style-src 'self' 'unsafe-inline'; script-src 'self' 'unsafe-inline'")
+		if strings.HasPrefix(r.URL.Path, "/api/") || r.URL.Path == "/" || r.URL.Path == "/index.html" {
+			w.Header().Set("Cache-Control", "no-store")
+		}
+		if r.Body != nil && r.Method != http.MethodGet && r.Method != http.MethodHead {
+			r.Body = http.MaxBytesReader(w, r.Body, maxAdminRequestBody)
+		}
+		next.ServeHTTP(w, r)
+	})
+}
+
+// writeFileAtomic replaces a sensitive configuration file without leaving a
+// partially written file behind after a crash or interrupted request.
+func writeFileAtomic(path string, data []byte, mode os.FileMode) error {
+	dir := filepath.Dir(path)
+	tmp, err := os.CreateTemp(dir, ".dragoncore-*.tmp")
+	if err != nil {
+		return err
+	}
+	tmpName := tmp.Name()
+	defer os.Remove(tmpName)
+	if err := tmp.Chmod(mode); err != nil {
+		tmp.Close()
+		return err
+	}
+	if _, err := tmp.Write(data); err != nil {
+		tmp.Close()
+		return err
+	}
+	if err := tmp.Sync(); err != nil {
+		tmp.Close()
+		return err
+	}
+	if err := tmp.Close(); err != nil {
+		return err
+	}
+	if err := os.Rename(tmpName, path); err != nil {
+		return fmt.Errorf("replace %s: %w", path, err)
+	}
+	return nil
+}