fix: 修复 TLS ConnectionState、SPA 回退、健康检查与监听小问题

internal/httpx/spa.go

@@ -0,0 +1,57 @@
+package httpx
+
+import (
+	"io"
+	"io/fs"
+	"net/http"
+	"path"
+	"strings"
+)
+
+// SPA 提供后台静态页：存在的文件原样返回；无扩展名的前端路由回退 index.html；
+// 有扩展名但不存在返回 404；访问目录不列清单，同样回退 index.html。
+func SPA(fsys fs.FS) http.Handler {
+	files := http.FileServer(http.FS(fsys))
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.Method != http.MethodGet && r.Method != http.MethodHead {
+			w.WriteHeader(http.StatusMethodNotAllowed)
+			return
+		}
+		cleaned := path.Clean("/" + r.URL.Path)
+		rel := strings.TrimPrefix(cleaned, "/")
+		if rel == "" {
+			rel = "."
+		}
+		fi, err := fs.Stat(fsys, rel)
+		if err == nil && !fi.IsDir() {
+			files.ServeHTTP(w, r)
+			return
+		}
+		if path.Ext(cleaned) != "" {
+			http.NotFound(w, r)
+			return
+		}
+		serveIndex(w, r, fsys)
+	})
+}
+
+func serveIndex(w http.ResponseWriter, r *http.Request, fsys fs.FS) {
+	f, err := fsys.Open("index.html")
+	if err != nil {
+		http.NotFound(w, r)
+		return
+	}
+	defer func() { _ = f.Close() }()
+	st, err := f.Stat()
+	if err != nil || st.IsDir() {
+		http.NotFound(w, r)
+		return
+	}
+	w.Header().Set("Cache-Control", "no-cache")
+	w.Header().Set("Content-Type", "text/html; charset=utf-8")
+	w.WriteHeader(http.StatusOK)
+	if r.Method == http.MethodHead {
+		return
+	}
+	_, _ = io.Copy(w, f)
+}