perf(服务端): 启用 h2c 并保留 HTTP/1.1 回退

README_CN.md

@@ -358,6 +358,29 @@ Invalid base URL: invalid url scheme: http
 ./sub2api
 ```
 
+#### HTTP/2 (h2c) 与 HTTP/1.1 回退
+
+后端明文端口默认支持 h2c，并保留 HTTP/1.1 回退用于 WebSocket 与旧客户端。浏览器通常不支持 h2c，性能收益主要在反向代理或内网链路。
+
+**反向代理示例（Caddy）：**
+
+```caddyfile
+transport http {
+	versions h2c h1
+}
+```
+
+**验证：**
+
+```bash
+# h2c prior knowledge
+curl --http2-prior-knowledge -I http://localhost:8080/health
+# HTTP/1.1 回退
+curl --http1.1 -I http://localhost:8080/health
+# WebSocket 回退验证（需管理员 token）
+websocat -H="Sec-WebSocket-Protocol: sub2api-admin, jwt.<ADMIN_TOKEN>" ws://localhost:8080/api/v1/admin/ops/ws/qps
+```
+
 #### 开发模式
 
 ```bash

backend/cmd/server/main.go

@@ -24,6 +24,8 @@ import (
 	"github.com/Wei-Shaw/sub2api/internal/web"
 
 	"github.com/gin-gonic/gin"
+	"golang.org/x/net/http2"
+	"golang.org/x/net/http2/h2c"
 )
 
 //go:embed VERSION
@@ -122,7 +124,14 @@ func runSetupServer() {
 	log.Printf("Setup wizard available at http://%s", addr)
 	log.Println("Complete the setup wizard to configure Sub2API")
 
-	if err := r.Run(addr); err != nil {
+	server := &http.Server{
+		Addr:              addr,
+		Handler:           h2c.NewHandler(r, &http2.Server{}),
+		ReadHeaderTimeout: 30 * time.Second,
+		IdleTimeout:       120 * time.Second,
+	}
+
+	if err := server.ListenAndServe(); err != nil && !errors.Is(err, http.ErrServerClosed) {
 		log.Fatalf("Failed to start setup server: %v", err)
 	}
 }

backend/internal/server/http.go

@@ -14,6 +14,8 @@ import (
 	"github.com/gin-gonic/gin"
 	"github.com/google/wire"
 	"github.com/redis/go-redis/v9"
+	"golang.org/x/net/http2"
+	"golang.org/x/net/http2/h2c"
 )
 
 // ProviderSet 提供服务器层的依赖
@@ -56,9 +58,10 @@ func ProvideRouter(
 
 // ProvideHTTPServer 提供 HTTP 服务器
 func ProvideHTTPServer(cfg *config.Config, router *gin.Engine) *http.Server {
+	handler := h2c.NewHandler(router, &http2.Server{})
 	return &http.Server{
 		Addr:    cfg.Server.Address(),
-		Handler: router,
+		Handler: handler,
 		// ReadHeaderTimeout: 读取请求头的超时时间，防止慢速请求头攻击
 		ReadHeaderTimeout: time.Duration(cfg.Server.ReadHeaderTimeout) * time.Second,
 		// IdleTimeout: 空闲连接超时时间，释放不活跃的连接资源

deploy/Caddyfile

@@ -87,6 +87,7 @@ example.com {
 		
 		# 连接池优化
 		transport http {
+			versions h2c h1
 			keepalive 120s
 			keepalive_idle_conns 256
 			read_buffer 16KB