Untitled

package main

import (
    "fmt"
    "io/ioutil"
    "log"
    "net/http"
    "net/http/cgi"
    "net/http/httputil"
    "net/url"
    "os"
    "path/filepath"
    "strings"
)

func main() {
    f, err := os.OpenFile(LogFile, os.O_RDWR|os.O_CREATE|os.O_APPEND, 0666)
    if err != nil {
        fmt.Println(err)
    }

    defer f.Close()
    log.SetOutput(f)
    if err := cgi.Serve(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {

        // ヘッダをセット
        header := w.Header()
        header.Set("Content-Type", "text/html; charset=utf-8")

        // パスを取得
        proxyPath := r.FormValue("proxyPath")
        if !filepath.IsAbs(proxyPath) {
            fmt.Fprintf(w, "Invalid request")
            return
        }
        formValue := r.Form

        // パスをQueryStringから消去
        formValue.Del("proxyPath")

        address, err := loadAddress(r.URL.Path)
        if err != nil {
            log.Fatalln(err)
        }

        target, err := url.Parse(address)
        if err != nil {
            log.Fatalln(err)
        }
        r.URL, err = url.Parse(address + proxyPath + "?" + formValue.Encode())
        if err != nil {
            log.Fatalln(err)
        }
        proxy := httputil.NewSingleHostReverseProxy(target)
        proxy.ServeHTTP(w, r)
    })); err != nil {
        log.Fatalln(err)
    }
}

<!DOCTYPE html>
<html>
  <head>
    <title>画像アップロードテスト</title>
    <meta charset="utf-8">
  </head>
  <body>
    <form method="post" action="/rev-proxy/?proxyPath=/upload" enctype="multipart/form-data">
      <input type="file" name="file">
      <input type="submit" value="送信">
    </form>
  </body>
</html>