Go 我无法使用反向代理更改主机标头

发布于04月30日

我正在为我的后端构建一个反向代理，但我不明白为什么即使我用文档中看到的任何方法更改主机头，它也不会更改. 后端需要真正的主持人才能提供正确的内容.

以下是代码:

proxy := &httputil.ReverseProxy{
    Director: func(req *http.Request) {
        targetURL := url.URL{
            Scheme: "http",
            Host:   "backend.com",
            Path:   req.URL.Path,
        }

        req.URL.Scheme = targetURL.Scheme
        req.URL.Host = targetURL.Host
        req.URL.Path = targetURL.Path
        req.Header.Set("Host", targetURL.Host)

    },
    Transport: transport,
}

// Listen on a local port and serve the reverse proxy without buffer method
server := &http.Server{
    Addr:    "localhost:8080",
    Handler: proxy,
}
fmt.Println("Listening on :8080...")
err = server.ListenAndServe()
if err != nil {
    fmt.Println(err)
}

推荐答案

如果你可以使用go1.20中添加的(*ProxyRequest).SetURL，就会很容易:

proxy := &httputil.ReverseProxy{
    Rewrite: func(pr *httputil.ProxyRequest) {
        targetURL := url.URL{
            Scheme: "http",
            Host:   "backend.com",
            Path:   req.URL.Path,
        }
        pr.SetURL(&targetURL)
    },
    Transport: transport,
}

有关更多信息，请参阅此提案:net/http/httputil: replace Director with Rewrite.

在不可能升级到Go 1.20的情况下，这里有一个适用于Director的解决方案:

  proxy := &httputil.ReverseProxy{
    Director: func(req *http.Request) {
        targetURL := url.URL{
            Scheme: "http",
            Host:   "backend.com",
            Path:   req.URL.Path,
        }

        req.URL.Scheme = targetURL.Scheme
        req.URL.Host = targetURL.Host
        req.URL.Path = targetURL.Path
-       req.Header.Set("Host", targetURL.Host)
+       req.Host = targetURL.Host
+       // or simply:
+       // req.Host = ""
    },
    Transport: transport,
  }

请参阅文档，了解http.Request.Host: