作者 | 那一片蓝海

来源 | urlify.cn/FJjmqa

需求描述：

　　项目里的几个Webapi接口需要进行鉴权，同接口可被小程序或网页调用，小程序里没有用户登录的概念，网页里有用户登录的概念，对于调用方来源是小程序的情况下进行放权，其他情况下需要有身份验证。也就是说给所有小程序请求进行放行，给网页请求进行jwt身份验证。由于我的小程序没有用户登录的功能，所以要针对小程序和网页设计出两套完全不同的鉴权方式。

鉴权流程设计：

　　查阅相关资料，最终决定的鉴权方式：

• 小程序采用sign签名检验
• 网页采用目前比较流行的JWT的token校验

通过AOP的思想使用.Net的Attribute进行拦截请求

代码实现

　　主要是服务端写一个Attribute，判断是小程序还是网页，然后采用不同的两种不同的鉴权方式。

• Attribute代码：

public class WxAllowFilterAttribute : BaseActionFilter
{
private static readonly int _errorCode = 401;
public override void OnActionExecuting(HttpActionContext filterContext)
{
var iswx = filterContext.iswx();//判断是否是小程序发来的请求
if (iswx)
{ //小程序的签名校验
if (!filterContext.checkwx()) {
filterContext.Response = Error("小程序签名验证失败", _errorCode);
};
}
else
{ //JWT的token校验
string token = filterContext.GetToken();
if (string.IsNullOrEmpty(token))
{
filterContext.Response = Error("缺少token", _errorCode);
return;
}
if (!JWTHelper.CheckToken(token, JWTHelper.JWTSecret))
{
filterContext.Response = Error("token校验失败!", _errorCode);
return;
}
var payload = JWTHelper.GetPayload<JWTPayload>(token);
if (payload.Expire < DateTime.Now)
{
filterContext.Response = Error("token过期!", _errorCode);
return;
}
base.OnActionExecuting(filterContext);
}
}
}

• 扩展类

public static class HttpRequest
{
public static readonly string wx_secret = ConfigurationManager.AppSettings["wx_secret"];
/// <summary>
/// 获取Token
/// </summary>
/// <param name="req">请求</param>
/// <returns></returns>
public static string GetToken(this HttpActionContext req)
{
string tokenHeader = req.Request.Headers.Authorization == null ? "" : req.Request.Headers.Authorization.Parameter;
if (string.IsNullOrEmpty(tokenHeader))
return null;
string pattern = "^Bearer (.*?)#34;;
if (!Regex.IsMatch(tokenHeader, pattern))
throw new Exception("token格式不对!格式为:Bearer {token}");
string token = Regex.Match(tokenHeader, pattern).Groups[1].ToString();
if (string.IsNullOrEmpty(token))
throw new Exception("token不能为空!");
return token;
}
/// <summary>
/// 判断是否微信
/// </summary>
/// <param name="req"></param>
/// <returns></returns>
public static bool iswx(this HttpActionContext req)
{
var queryList = req.Request.RequestUri.Query.Split('&').ToList<string>();
Dictionary<String, String> pList = new Dictionary<String, String>();
if (queryList.Count < 2)
{
return false;
}
else
{
queryList.ForEach(x =>
{
var a = x.Split('=');
if (a.Count() >= 2)
{
pList.Add(a[0], a[1]);
}
});
var iswx = pList.Any(x => x.Key == "app_key" && x.Value == "wx");//判断是否有微信标识的字段
return iswx;
}
}
/// <summary>
/// 检验微信sign是否合法
/// </summary>
/// <param name="req"></param>
/// <returns></returns>
public static bool checkwx(this HttpActionContext req)
{
var queryList = req.Request.RequestUri.Query.Split('&').ToList<string>();
Dictionary<String, String> pList = new Dictionary<String, String>();
queryList.ForEach(x =>
{
var a = x.Split('=');
if (a.Count() >= 2)
{
pList.Add(a[0], a[1]);
}
});
var app_key = pList["app_key"];
var app_secret = wx_secret;
var timetamp = pList["timestamp"];
var sign = pList["sign"];
if (!string.IsNullOrEmpty(timetamp)) {
var tamp=Convert.ToInt64(timetamp);
var nowtamp = ToTimestamp(DateTime.Now);
var a = nowtamp-tamp;
if (a >= 15) {
return false;
}
}
StringBuilder sb = new StringBuilder();
sb.Append(app_key);
sb.Append(app_secret);
sb.Append(timetamp);
var newsign = GetMD5(sb.ToString());
return newsign == sign;
}
public static string GetMD5(string sDataIn)
{
MD5CryptoServiceProvider provider = new MD5CryptoServiceProvider();
byte[] bytes = Encoding.UTF8.GetBytes(sDataIn);
byte[] buffer2 = provider.ComputeHash(bytes);
provider.Clear();
string str = "";
for (int i = 0; i < buffer2.Length; i++)
{
str = str + buffer2[i].ToString("X").PadLeft(2, '0');
}
return str.ToLower();
}
public static long ToTimestamp(this DateTime target)
{
return (target.ToUniversalTime().Ticks - 621355968000000000) / 10000000;
}
}

• Filter基类

public class BaseActionFilter : ActionFilterAttribute
{
//public virtual void OnActionExecuting(HttpActionContext filterContext)
//{
//}
//public virtual void OnActionExecuted(HttpActionContext filterContext)
//{
//}
/// <summary>
/// 返回JSON
/// </summary>
/// <param name="json">json字符串</param>
/// <returns></returns>
public HttpResponseMessage JsonContent(string json)
{
var content = new StringContent(json, Encoding.UTF8, "application/json");
return new HttpResponseMessage { Content = content, StatusCode = HttpStatusCode.OK };
}
public HttpResponseMessage IsSuccess()
{
AjaxResult res = new AjaxResult
{
IsSuccess = true,
Msg = "请求成功！"
};
return JsonContent(JsonHelper.SerializeObject(res));
}
/// <summary>
/// 返回成功
/// </summary>
/// <param name="msg">消息</param>
/// <returns></returns>
public HttpResponseMessage IsSuccess(string msg)
{
AjaxResult res = new AjaxResult
{
IsSuccess = true,
Msg = msg
};
return JsonContent(JsonHelper.SerializeObject(res));
}
/// <summary>
/// 返回成功
/// </summary>
/// <param name="data">返回的数据</param>
/// <returns></returns>
public HttpResponseMessage IsSuccess<T>(T data)
{
AjaxResult<T> res = new AjaxResult<T>
{
IsSuccess = true,
Msg = "请求成功！",
Data = data
};
return JsonContent(JsonHelper.SerializeObject(res));
}
/// <summary>
/// 返回错误
/// </summary>
/// <returns></returns>
public HttpResponseMessage Error()
{
AjaxResult res = new AjaxResult
{
IsSuccess = false,
Msg = "请求失败！"
};
return JsonContent(JsonHelper.SerializeObject(res));
}
/// <summary>
/// 返回错误
/// </summary>
/// <param name="msg">错误提示</param>
/// <returns></returns>
public HttpResponseMessage Error(string msg)
{
AjaxResult res = new AjaxResult
{
IsSuccess = false,
Msg = msg,
};
return JsonContent(JsonHelper.SerializeObject(res));
}
/// <summary>
/// 返回错误
/// </summary>
/// <param name="msg">错误提示</param>
/// <param name="errorCode">错误代码</param>
/// <returns></returns>
public HttpResponseMessage Error(string msg, int errorCode)
{
AjaxResult res = new AjaxResult
{
IsSuccess = false,
Msg = msg,
StatusCode = errorCode
};
return JsonContent(JsonHelper.SerializeObject(res));
}
}

• JWT扩展类

public class JWTHelper
{
private static readonly string _headerBase64Url = "{\"alg\":\"HS256\",\"typ\":\"JWT\"}".Base64UrlEncode();
public static readonly string JWTSecret = ConfigurationManager.AppSettings["JWTSecret"];
/// <summary>
/// 生成Token
/// </summary>
/// <param name="payloadJsonStr">数据JSON字符串</param>
/// <param name="secret">密钥</param>
/// <returns></returns>
public static string GetToken(string payloadJsonStr, string secret)
{
string payloadBase64Url = payloadJsonStr.Base64UrlEncode();
StringBuilder sb = new StringBuilder();
StringBuilder sb1 = new StringBuilder();
sb.AppendFormat("{0}", _headerBase64Url);
sb.Append(".");
sb.AppendFormat("{0}", payloadBase64Url);
sb1 = sb;
string sign = sb.ToString().ToHMACSHA256String(secret);
string token = sb1.AppendFormat(".{0}", sign).ToString();
return token;
}
/// <summary>
/// 获取Token中的数据
/// </summary>
/// <typeparam name="T">泛型</typeparam>
/// <param name="token">token</param>
/// <returns></returns>
public static T GetPayload<T>(string token)
{
if (string.IsNullOrEmpty(token))
{
return default(T);
}
return token.Split('.')[1].Base64UrlDecode().ToObject<T>();
}
/// <summary>
/// 校验Token
/// </summary>
/// <param name="token">token</param>
/// <param name="secret">密钥</param>
/// <returns></returns>
public static bool CheckToken(string token, string secret)
{
var items = token.Split('.');
var oldSign = items[2];
StringBuilder sb = new StringBuilder();
sb.AppendFormat("{0}", items[0]);
sb.AppendFormat(".{0}", items[1]);
string newSign = sb.ToString().ToHMACSHA256String(secret);
return oldSign == newSign;
}
}

检验用户名密码是否正确的业务接口代码这里不贴了..

网页客户端的代码还没写完，主要思路就是判断缓存里是否有token，没有就去把用户名密码去调用服务端的登录接口拿到token后存到缓存里，之后的所有请求都在头部带上这个token。

小程序客户端代码 :

在app.js中定义一个公共的promise请求方法，并带上请求的参数(app_key,时间戳,md5加密后的sign等)，这里要注意区分get和post请求的区别，get是放在url后的,post是放在body里的，要对传参的格式要稍加处理

request(params) {
reqTime++;
//加载弹框
wx.showLoading({
title: '加载中...',
mask: true
});
//返回
return new Promise((resolve, reject) => {
var data = {
app_key: this.globalData.app_key,
timestamp: Math.round(new Date() / 1000),
sign: ''
}
data.sign = utilMd5.hexMD5(`${this.globalData.app_key}${this.globalData.app_secret}${data.timestamp}`)
if (params.method.toUpperCase() == 'POST') {
if (!params.url.includes('?')) {
params.url += '?'
}
var url = `&app_key=${this.globalData.app_key}×tamp=${data.timestamp}&sign=${data.sign}`
params = {
...params,
url: params.url + url
}
data = params.data
} else {
data = {
...params.data,
...data
}
}
params = {
...params,
data: {
...data
}
}
wx.request({
//解构params获取请求参数
...params,
success: (result) => {
resolve(result);
},
fail: (err) => {
reject(err);
},
complete: () => {
reqTime--;
//停止加载
if (!reqTime)
wx.hideLoading();
}
});
});
}

这边说明下，我的app_key和app_secret都是写在app.js里的公共变量中的，app_key在url里是暴露的，但是app_secret是绝不能被暴露的。光知道app_key是无法生成正确的sign的，必须app_key,app_secret和timestap三者的加密才能生成正确的sign。我把app_secret写在app.js中可能不是安全的做法，但是通过请求服务器去获取app.secret又要面临网络请求的安全问题，最多对字符串进行加密解密，但也不能说绝对安全了。app_secret怎么处理最安全我目前也没想到很好的办法。。

好了，以上就是小程序的鉴权方法，小程序客户端在请求时只需要调用这个公共方法就行。

鉴权测试结果

• 给控制器或者方法前面加上鉴权的特性[WxAllowFilter]

• PostMan直接调用不带任何sign等参数

• 伪造小程序参数签名验证失败或者时间戳超过10秒

• 小程序内调用