refactor(proxy): 提取 X-Forwarded 头处理为独立模块

提取 ForwardedHeaders 结构体和 SetForwardedHeaders/WriteForwardedHeaders
函数，消除 proxy.go 和 websocket.go 中的重复代码。

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

internal/proxy/headers.go

@@ -0,0 +1,107 @@
+// Package proxy 反向代理包，为 Lolly HTTP 服务器提供反向代理功能。
+//
+// 该文件提供统一的 X-Forwarded 头设置逻辑。
+package proxy
+
+import (
+	"strings"
+
+	"github.com/valyala/fasthttp"
+	"rua.plus/lolly/internal/netutil"
+)
+
+// ForwardedHeaders 包含 X-Forwarded 系列头信息。
+type ForwardedHeaders struct {
+	ClientIP string // 客户端 IP
+	Host     string // 原始 Host
+	Proto    string // 协议 (http/https)
+}
+
+// ExtractForwardedHeaders 从请求上下文中提取 X-Forwarded 头信息。
+//
+// 参数：
+//   - ctx: FastHTTP 请求上下文
+//
+// 返回值：
+//   - ForwardedHeaders: 提取的头信息
+func ExtractForwardedHeaders(ctx *fasthttp.RequestCtx) ForwardedHeaders {
+	clientIP := netutil.ExtractClientIP(ctx)
+	host := string(ctx.Host())
+
+	proto := "http"
+	if ctx.IsTLS() {
+		proto = "https"
+	}
+
+	return ForwardedHeaders{
+		ClientIP: clientIP,
+		Host:     host,
+		Proto:    proto,
+	}
+}
+
+// SetForwardedHeaders 设置 X-Forwarded 系列请求头。
+//
+// 参数：
+//   - headers: 目标请求头
+//   - fh: ForwardedHeaders 结构体
+//   - appendXFF: 是否追加到已有的 X-Forwarded-For 头
+func SetForwardedHeaders(headers *fasthttp.RequestHeader, fh ForwardedHeaders, appendXFF bool) {
+	// 设置 X-Real-IP
+	if fh.ClientIP != "" {
+		headers.Set("X-Real-IP", fh.ClientIP)
+	}
+
+	// 设置 X-Forwarded-For
+	if fh.ClientIP != "" {
+		if appendXFF {
+			existingXFF := headers.Peek("X-Forwarded-For")
+			if len(existingXFF) > 0 {
+				headers.Set("X-Forwarded-For", string(existingXFF)+", "+fh.ClientIP)
+			} else {
+				headers.Set("X-Forwarded-For", fh.ClientIP)
+			}
+		} else {
+			headers.Set("X-Forwarded-For", fh.ClientIP)
+		}
+	}
+
+	// 设置 X-Forwarded-Host
+	if fh.Host != "" {
+		headers.Set("X-Forwarded-Host", fh.Host)
+	}
+
+	// 设置 X-Forwarded-Proto
+	if fh.Proto != "" {
+		headers.Set("X-Forwarded-Proto", fh.Proto)
+	}
+}
+
+// WriteForwardedHeaders 将 X-Forwarded 头写入到 strings.Builder。
+// 用于 WebSocket 升级请求构建。
+//
+// 参数：
+//   - builder: strings.Builder 实例
+//   - fh: ForwardedHeaders 结构体
+func WriteForwardedHeaders(builder *strings.Builder, fh ForwardedHeaders) {
+	if fh.ClientIP != "" {
+		builder.WriteString("X-Forwarded-For: ")
+		builder.WriteString(fh.ClientIP)
+		builder.WriteString("\r\n")
+		builder.WriteString("X-Real-IP: ")
+		builder.WriteString(fh.ClientIP)
+		builder.WriteString("\r\n")
+	}
+
+	if fh.Host != "" {
+		builder.WriteString("X-Forwarded-Host: ")
+		builder.WriteString(fh.Host)
+		builder.WriteString("\r\n")
+	}
+
+	if fh.Proto != "" {
+		builder.WriteString("X-Forwarded-Proto: ")
+		builder.WriteString(fh.Proto)
+		builder.WriteString("\r\n")
+	}
+}

internal/proxy/proxy.go

@@ -628,32 +628,9 @@ func (p *Proxy) getClient(targetURL string) *fasthttp.HostClient {
 func (p *Proxy) modifyRequestHeaders(ctx *fasthttp.RequestCtx, _ *loadbalance.Target) {
 	headers := &ctx.Request.Header
 
-	// 添加 X-Real-IP 请求头
-	clientIP := netutil.ExtractClientIP(ctx)
-	if clientIP != "" {
-		headers.Set("X-Real-IP", clientIP)
-	}
-
-	// 添加/追加 X-Forwarded-For 请求头
-	existingXFF := headers.Peek("X-Forwarded-For")
-	if len(existingXFF) > 0 {
-		headers.Set("X-Forwarded-For", string(existingXFF)+", "+clientIP)
-	} else {
-		headers.Set("X-Forwarded-For", clientIP)
-	}
-
-	// 添加 X-Forwarded-Host 请求头
-	host := string(ctx.Host())
-	if host != "" {
-		headers.Set("X-Forwarded-Host", host)
-	}
-
-	// 添加 X-Forwarded-Proto 请求头
-	proto := "http"
-	if ctx.IsTLS() {
-		proto = protoHTTPS
-	}
-	headers.Set("X-Forwarded-Proto", proto)
+	// 提取并设置 X-Forwarded 系列头
+	fh := ExtractForwardedHeaders(ctx)
+	SetForwardedHeaders(headers, fh, true)
 
 	// 从配置设置自定义请求头（支持变量展开）
 	if p.config.Headers.SetRequest != nil {

internal/proxy/websocket.go

@@ -287,22 +287,8 @@ func buildWebSocketUpgradeRequest(ctx *fasthttp.RequestCtx, targetHost string) s
 	}
 
 	// 添加 X-Forwarded 头
-	clientIP := netutil.ExtractClientIP(ctx)
-	if clientIP != "" {
-		fmt.Fprintf(&req, "X-Forwarded-For: %s\r\n", clientIP)
-		fmt.Fprintf(&req, "X-Real-IP: %s\r\n", clientIP)
-	}
-
-	host := string(ctx.Host())
-	if host != "" {
-		fmt.Fprintf(&req, "X-Forwarded-Host: %s\r\n", host)
-	}
-
-	proto := "http"
-	if ctx.IsTLS() {
-		proto = "https"
-	}
-	fmt.Fprintf(&req, "X-Forwarded-Proto: %s\r\n", proto)
+	fh := ExtractForwardedHeaders(ctx)
+	WriteForwardedHeaders(&req, fh)
 
 	// 结束请求头
 	req.WriteString("\r\n")